ECOLOGY OF IMPORTANT INVASIVE MACROPHYTES AND EMERGING MANAGEMENT SCENARIOS FOR WULAR LAKE, KASHMIR, INDIA
ABSTRACT THESIS
SUBMITTED FOR THE AWARD OF THE DEGREE OF
IBoctor of $}|tIofitopi)p
IN BOTANY
BY ATHER MASOODI
DEPARTMENT OF BOTANY ALIGARH MUSLIM UNIVERSITY ALIGARH (U.P.) INDIA 2013 ABSTRACT
Ecology of important invasive macrophytes and emerging management scenarios for Wular Lake, Kashmir, India
ATHER MASOODI
Abstract of the thesis submitted to the Aligarh Muslim University, Aligarh, India, for the award of the degree of Doctor of Philosophy in Botany, in the year 2013.
Invasive macrophytes have been shown to cause local extinctions of native species, and alter ecosystem-'l'.roetesses.sucn •a^.nutrient cycling, hydrology, and plant f ^ V- 'Mil ' productivity in their new eh/Vironment. Thev^-Jey of Kashmir has numerous natural lakes and wetlands, rich"',;© lgioai\^ersity..Invasive«Tiacrophytes are a major threat to these lakes and wetlands, ^kii^aye-been poorly studied. The present work was carried out durmg 2008 and 2011 in Wiiiar Lake, the largest freshwater lake in India and a Ramsar site. Six sites were selected for intensive sampling during the study period. The present study was focused on four invasive macrophytes viz., Trapa natans (Linn.), (Lythraceae), Nymphoides peltata (S.G.Gmel.) (Menyanthaceae), Alternanthera philoxeroides (Mart.) Griseb, (Amaranthaceae) and Azolla cristata Kaulf The selected species differ in their habit, so it was difficult to have a common approach for studying their ecology. Species specific parameters were studied in this thesis.
The thesis is divided into 7 chapters. In Chapter 1, the problem of aquatic invasive macrophytes is discussed and the traits that enable some species to colonize the new regions and habitats are reviewed. In chapter 2, the study area is discussed and the peculiar features of the different selected sites are identified.
In Chapter 3, the temporal changes in the composition of macrophyte communities and environmental factors governing the distribution of selected invasive macrophytes was studied. This chapter has several objectives and a brief account of all these objectives is given. The first objective was to document the macrophyte composition of the lake. A total of 33 species of macrophytes distributed over 27 genera and 22 families were recorded in Wular Lake. Eight macrophytes collected in this survey including Bidens cernua L, Lycopus europaeus L., Veronica anagallis-aquatica L., Alternanthera philoxeroides (Mart.) Griseb, Echinochloa crusgalli Beauv., Potomogeton pectinatus L. and Vallisneria spiralis L. were not previously reported from Wular Lake,. Alternanthera philoxeroides (Mart.) Griseb of the family Amaranthaceae is an invasive weed originally from South America and was reported first time from this Himalayan valley. Identification of Azolla cristata was ascertained with the help of scanning electron microscopy. Pluriseptate gochidia with a distinct terminal anchor, granular megaspore perine surface and bicellular leaf trichomes are specific to Azolla cristata. The thickness of the Azolla mats in Wular lake range between 5-10 cm and cause severe degradation of the ecosystem, besides direct economic loss to lake inhabitants who rely on this ecosystem for their livelihoods.
The second objective was to make an assessment of the abundance of the macrophytes in the lake. A floating (Im x Im) quadrat was used to record vegetation at the selected sites along many transects that best represented aquatic macrophyte composition. A total of 90 quadrats on each sampling occasion in spring, summer and autumn were laid and rated the abundance of plant species (rooted floating and emergents) present within the sample visually on a Domin-Krajina cover scale (1 = <20%; 2 = 21-40%; 3 = 41-60%; 4 = 61-80%; 5 = 81-100% of covering). For submerged species, a rake was used in these locations. The most frequent species recorded in Wular lake were Trapa natans (66.67%), Azolla cristata (61.11%), Nymphoides peltata (37.78%), Phragmites australis (28%), Ceratophyllum demersum (22%), Potomogeton lucens (20%) and Hydrocharis dubia. Among the selected invasive species, the abundance of Alternanthera philoxeroides had increased significantly from a mean value of 0.72 ±0.28 in 2008 to 4.50 ±0.71 in year 2011 (p<0.05). The mean abundance of Azolla cristata also increased significantly from 6.50 ±0.85 in 2008 to 8.28 ±0.96 in 2011. The mean abundance of Trapa natans has decreased from 18.66 ±1.42 in 2008 to 16.17 ±1.34 in 2011 (p<0.05). The abundance of Nymphoides peltata has also declined in year 2011, though statistically non significant (p>0.05). The results revealed that Alternanthera philoxeroides invasion was having a selective impact on different life forms of macrophytes. There was a decrease in the overall diversity of macrophytes with a significant decrease in the diversity of free floating macrophytes. Sampling of water and sediment was also done seasonally corresponding to the sites of macrophytes. Water depth ranged from a minimum of 0.2m to a maximum of 4.4 m. The overall mean depth of the lake in 2008 was 2.10 m and in 2011 the average depth was 1.97m. Water transparency ranged from 0.2-2.4 m in the lake. Dissolved oxygen had higher concentration in winter and lowest in summer, exhibiting the expected physical property of decreased gas solubility with increasing temperature.
The concentration of calcium was much higher than that of magnesium and ranged from 17 mg/L at S2 in summer 2008 to 71 mg/L at S3 in winter 2011. Magnesium concentration ranged from 5.5 mg/L at S6 in summer 2008 to 36.5 mg/L at S4 in winter 2008. Magnesium and potassium also varied seasonally with decrease in their concentration during summer months corresponding to the peak growth of macrophytes, besides reduced surface runoff owing to decrease in rainfall in summer. No definite trend was observed for sodium as it fluctuated irregularly both in time and space in the lake. The cationic content of the waters revealed predominance of mineral ions in the order of Ca > Mg > Na > K as is known for freshwater lakes of Kashmir. The conductivity ranged from 170 ^SCm'" at site SI to 452 |iSCm''at site S3 with an overall mean of 278.08 |j,SCm"". The seasonal fluctuation of conductivity is mostly relate with the biological activity as the low value during summer months is due to uptake of ions by autotrophs during their growing season along with precipitation of calcium carbonate which is the main contributor to conductivity.
The chemistry of lake water and sediment is the indicator of catchment geology, weathering and erosional processes as well as anthropogenic activities. The textural and geochemical studies of Wular lake sediments have revealed that physical weathering dominated over chemical weathering, resulting in enhanced rates of erosion and consequent deposition of huge detritus into the lake. The granulometric characteristics results revealed silt and clay to be the major constituents of the lake sediments. The overall soil type of the lake can thus be classified as 'silt-loam'.
Canonical correspondence analysis revealed that the abundance and distribution of Alternanthera philoxeroides and Azolla cristata was not governed by any single factor or factors, rather they use the resources differentially to increase their abundance. Chapter 4 deals with the predictive modeling of A. philoxeroides spread in the lake. The abundance data revealed that A. philoxeroides was rapidly increasing in abundance in Wular lake. It is a noxious invasive weed worldwide and proliferates rapidly by fragmentation. We did predictive modeling with four year data using a variable growth rate equation, to estimate the spread rate of the weed assuming the entire lake area available for spread. Our model suggests that this weed may potentially cover entire lake in 13-19 years from 2008. The robustness of the mathematical model was also determined and validated using data from the first three years and it was in coherence with the previous model. The study warrants an urgent need for rapid action involving manual removal before it actually assumes bigger dimensions in the lake and the region as more than ten thousand households completely depend on the resources of Wular Lake, India.
Chapter 5 deals with the ecology of Trapa natans in Wular lake. The growth and phenology of Trapa natans was ascertained in Wular lake. Geographic Information System (GIS) was used to map the distribution of the plant in the lake. Sampling was done every 4 weeks from April 2009 to September 2009 using a (Imxlm) quadrat and density of rosettes was measured. Various morphological parameters viz., the rosette diameter, number of leaves per rosette and area per leaf were also measured by sampling 10-15 rosettes randomly at each site. T. natans rosettes start to appear on the water surface in early April and form dense mats by the end of May. Rosette diameter increased from April and stabilized in the month of July. The remaining vegetative characteristics of the plant including biomass, rosette number and number of leaves per rosette also increase by the time flowering starts (Table 5.2). As soon as the flowering and fruit formation starts, allocation of resources changes from vegetative to reproductive structures. This is an effective strategy of T. natans to segregate vegetative growth and seed production in a season, hence minimizing the competition between these two activities. Sedimentation of the lake has resulted in shifting of the dense stands of the plant into the lake.
In chapter 6 the growth and reproductive biology of Nymphoides peltata was studied. N. peltata commonly known as yellow floating heart or fringed water lilly is a very widespread invasive macrophyte in Kashmir. The species is distylous showing pin and thrum morphs in its populations. 25 populations of N. peltata were investigated in Wular lake and other major lakes of Kashmir. Each population was analyzed for floral morph ratio by sampling flowering ramets randomly. The populations of A^. peltata in Wular lake are characterized by extreme spatial segregation of the floral morphs. The results reveal that clonal propagation appears to be the main reproductive strategy of Nymphoides peltata in Wular Lake.
Based on the results some management recommendations are summarized in Chapter 7. Weed management is identified as a priority for the effective management of the lake. Areas for dredging have been marked in the lake. Establishment of early detection and rapid response systems should be a priority for management of invasive species. Monitoring of the macrophyte community especially the spread of A. philoxeroides in the lake will be vital for more accurate modeling of this species in space and time. ECOLOGY OF IMPORTANT INVASIVE MACROPHYTES AND EMERGING MANAGEMENT SCENARIOS FOR WULAR LAKE, KASHMIR, INDIA
THESIS
SUBMITTED FOR THE AWARD OF THE DEGREE OF
Bottor of $I)tlos!op]bP IN BOTANY
BY ATHER MASOODI
DEPARTMENT OF BOTANY ALIGARH MUSLIM UNIVERSITY ALIGARH (U.P.) INDIA 2013 2 4 OCT 2014
T8638 DEDICATED TO MY PARENTS Vareed^hmad%han /^^^^^ Department of Botany Ph.D.F B S..K.A.LB. iffff'^KS^^^ Aligarh Muslim University Associate Professor X^f&fnj Aligarh-202002, India. ^^^^/ Mobile: 09808618275 ^— Email: fareedkhan.amu2007;a),redifF.com
Certificate
l^w is to certify that the thesis entitled, "Ecology of important invasive macropfiytes and emerging management scenarios for Wtddr
La^, IQlsfimir, India", suSmittedfor the degree of doctor of iphdbsophy in
(Botany is a faithfuf record of the Sonafide research wor^ carried out at
Jifigarh !MusCim Vniversity, JlCigarh, India, 6y Mr. Mher 9iiasoodi under my
guidance and supervision and that no part of it has Seen suSmittedfor any
other degree ordipComa.
(Dr. Fareed A. Khan) Research Supervisor ACKNOWLEDGEMENT
ALLAH, the almighty, the lord of all worlds, the most merciful, the most gracious, be witness, I acknowledge you every minute and greatest blessing on me, apparent and hidden favours, from the time before, to the time after this life, in all the quarters, including my research and writing of this PhD thesis, just for my belief in you.
I want to express my sincere thanks to my Research Supervisor, Dr. Fareed A. Khan, Associate Professor, Department of Botany, for giving me an opportunity to work on this topic. His constant supervision and constructive criticism helped me immensely throughout the period of my PhD research. I am thankful to him for encouraging me to undertake several training programs related to aquatic weed management in India and abroad.
I am highly thankful to Prof. Firoz Mohammad, Chairman, Department of Botany, Aligarh Muslim University, for providing the necessary facilities during the research work. I take this opportunity to express gratitude to Dr. A.M. Kak, Research Co ordinator at Islamia College, Srinagar for his help in identification of macrophytes. I am thankful to Dr. Khursheed A. Ganaie, who motivated me for this study and has been inspiring right from the days; I joined university for my Masters degree. I express my sincere thanks to Dr. Gyan P. Sharma, Assistant professor at Delhi University and to Dr. Anand Sengupta at IIT Gandhinagar for their encouragement.
1 express special thanks to Dr. Jonathan Newman, Head, APMG group at CEH Wallingford, UK for hosting my vish to CEH and allowing me to work with him on various techniques of aquatic plant management and help in identification of aquatic plants. Thanks are due to Dr. Rob Reeder and Corin Pratt at CABI, UK for training me in biological control of Azolla using AzoUa weevil. I am thankful to Prof James Cuda and Dr. Abhishekh, at CAIP Florida for hosting my training on various aspects of biological control techniques. Thankful to scientists at NRSC Hyderabad for training on use of RS and GIS in vegetation science. Thanks are due to due to Aquatic plant management society for sponsoring my training on underwater macrophyte sampling at Cheasapeake Bay in Maryland. Thankful to Director, Wadia Institute of Himalayan Geology, for allowing analysis of sediment samples and SEM facilities.
I am highly grateful to Department of Botany, Aligarh Muslim University for providing all necessary facilities for the successful completion of my research. I would also like to thank Dr. Athar Ali Khan and Dr. Afif A Khan at AMU for their support and encouragement during this study.
I am extremely thankful to local people around the Wular lake, who made available their boats and ferried me to different sites in the lake during this study. I am very thankful to my brother who has been a constant support and inspiration all through my life. His co-operation has encouraged me to dream.
I would like to thank my fellow lab mates: Farha Rehman, Dipshikha and Mudasir. You have all been great friends. Special thanks to my very good friends Arshad Masoodi and Zubair Masoodi for their encouragement and support. My Friends in the Department Irfan, Muzaffar, Mudasir, Zehra and Tariq for their support. Besides research activities, I also enjoyed my stay at residential Hostel and this time wouldn't have been fun, had it not been with people like Zia ul Haq, Jan Mohammad and Mumtaz. It is a pleasure to thank many of my friends back home (especially those from my undergrad years) for their constant encouragement.
Special thanks are due to various funding agencies in India viz., CSIR, DST and CICS for sponsoring these trainings and workshops. Special thanks to UGC for providing me fellowship during the entire study period.
I am at a loss for words to thank my family for being the best people, I know. No words are ever sufficient to express my everlasting love, gratitude, appreciation and thanks to my Dad, Mom, my sisters and my brother in laws.
(ATHER MASOODI) TABLE OF CONTENTS
List of Tables i-ii List of Figures iii-vi Chapters 1 Introduction 1-21 1.1 Alien species and the invasion process 1 1.2 Reviewof species invasive traits 4 1.3 The impact of invasive macrophytes 11 1.4 Socio-economic impacts of aquatic macrophyte invasions 14 1.5 Abiotic factors and macrophyte invasions 15 1.6 Studies on invasive macrophytes in india 18 2 Study area 22 - 29 2.1 Location and extent 22 2.2 Importance of the lake 23 2.3 Climate 23 2.4 Geology 24 2.5 Description of study sites 24 2.5.1 Site 1 (SI) 24 2.5.2 Site 2 (S2) 24 2.5.3 Site 3 (S3) 25 2.5.4 Site 4 (S4) 25 2.5.5 Site 5 (S5) 25 2.5.6 Site 6 (S6) 26
3 Temporal changes in the composition of macrophyte communities and 30 - 89 environmental factors governing the distribution of selected invasive macrophytes in Wular lake, Kashmir, India Summary 30 3.1 Introduction 31 3.2 Material and methods 33 3.2.1 Study Species 34 3.2.2 Macrophyte Sampling 35 3.2.3 Physical And Chemical Analysis of Water 36 3.2.4 Sediment Analysis 43 3.2.5 Chemical Analysis of Plant Mineral Nutrients 43 3.2.6 Statistical Analysis 44 3.3 Results 45 3.3.1 Macrophytes 45 3.3.2 Physico-Chemical Characteristics of Water 47 3.3.3 Sediment Characteristics 68 3.3.4 Mineral Nutrients in Plants 71 3.3.5 Canonical Correspondence Analysis 78 3.4 Discussion 85 3.5 Conclusion 89 Predicting the spread of alligator weed ^Iternanthera philoxeroides) in 90-106 wular lake, India: A mathematical approach Summary 90 4.1 Introduction 91 4.2. Material and methods 92 4.2.1 Study Area 92 4.2.2 Sampling 93 4.2.3 Predictive Analysis 93 4.2.4 Statistical Analysis 95 4.3. Results 95 4.4. Discussion 96 4.5. Conclusion 98 Ecology of Trapa nutans, an invasive macrophyte in Wular lake 107-127 Summary 107 5.1 Introduction 108 5.2 Material and methods 109 5.2.1 Study Area 109 5.2.2 Study Species 109 5.2.3 Water Chestnut Distribution Mapping 110 5.2.4 Field Sampling 110 5.2.5 Statistical Analysis 111 5.3 Results 5.3.1 Historical And Present Distribution Of Trapa ttatam 11] 5.3.2 Biomass 112 5.3.3 Rosette Number 112 5.3.4 Rosette Diameter 113 5.3.5 Area Per Leaf 113 5.3.6 Leaf Number Per Rosette 113 5.3.7 Number Of Rosettes Per Plant 114 5.3.8 Fruit Number Per Rosette 114 5.4 Discussion 114 5.5 Conclusion 117 Morph Ratio, Mating Pattern And Incipient Gender Specialization in 128-147 Nymphoides Peltata - An Invasive Species in Wular Lake of Kashmir
Summary 128 6.1 Introduction 129 6.2 Material And Methods 131 6.2.1 Plant Material And Study Area 131 6.2.2 Distribution Of Nymphoides t>eltala in Wular Lake 132 6.2.3 Morph Ratios In Natural Population 132 6.2.4 Controlled Hand-Pollinations 132 6.2.5 Morph Ratio And Fruit Set 132 6.2.6 Gender Specializations 133 6.2.7 Vegetative Reproduction by Short Overwintering Rhizomes 133 6.3 Results 133 6.3.1 Distribution of Nymphoides Peltata in Wular Lake 133 6.3.2 Density Of Short Rhizomes 134 6.3.3 Variations in Floral Morph Ratios 134 6.3.4 Mating System 134 6.3.5 Floral Morph Ratio and Seed Set 135 6.3.6 Potential Gender Specialization 135 6.4 Discussion 135
6.5 Conclusion 138
Summary 148-152
References 153-185 LIST OF TABLES
Table No. Title
2.1 Demographic features of the settlements around Wular Lake and Resource linkages (as per 2001 Census)
3.1 List of macrophytes recorded from Wular Lake in the present study
3.2 Abundance of macrophytes in Wular Lake during 2008 and 2011 (Actual mean ±SE is given) 3.3 Range, mean and SD of different water quality parameters in Wular lake during 2008 and 2011 3.4 Mean values of the different water quality parameters at the selected sites for year 2008 and 2011 3.5 Mean seasonal values of the different water quality parameters for year 2008 and 2011 3.6 Mean yearly values of the different water quality parameters for year 2008 and 2011 3.7 Principal components and Varimax rotated components of 17 water quality parameters studied.
3.8 Granulometric composition of lake sediments
3.9 Range, mean and SD of sediment characteristics in Wular lake during 2008 and 2011 3.10 Site wise overall mean of the sediment characteristics in Wular lake during 2008 and 2011 3.11 Seasonal mean of the sediment characteristics in Wular lake during 2008 and 2011 3.12 Yearly mean of the sediment characteristics in Wular lake during 2008 and 2011 3.13 Principal components and varimax rotated components of the different parameters of sediment analyzed in the present study
3.14 Mean seasonal values of tissue concentration (%) of mineral nutrients in the selected species.
3.15 Eigenvalues, percentage variance and total inertia of the canonical correspondence analysis (CCA) axes between the species and environmental variables for different seasons and overall for year 2008 and 2011.
4.1 Number of patches of ^. philoxeroides in Wular lake during 2008-2011
4.2 The values of growth rates obtained from the regression analysis and other parameters. 4.3 Various symbols in equation 1 and elsewhere in tliis cliapter are explained below: 5.1 Range, mean and SD of various characteristics of Trapa nutans in Wular lake. Rosette diameter, area per leaf and leaf number per rosette are of primary rosettes. 5.2 Site wise mean monthly values of different parameters of the Trapa nutans in Wular Lake. Rosette diameter, area per leaf and leaf number per rosette are of primary rosettes.
5.3 Number of fruits per rosette from July to August. Sampling number is given in parenthesis. 6.1 Results of floral morph proportions of the Nymphoides peltata populations studied in various lakes of Kashmir LIST OF FIGURES
Figure No. Title
1.1 The unified framework for biological invasions. 2.1 Location map of Wular lake. 2.2 Wular lake within Jhelum basin (modified after wetlands international 2007). 2.3 Human settlements along the shore line of Wular lake.
3.1 Nymphoides peltata (A) mature plants (B) flower and (C) overview of invasion by the species in Wular lake, Kashmir
3.2 Alternantheraphiloxeroides (A) mature plant (B) inflorescence (C) and (D) overview of invasion by the species in Wular Lake, Kashmir
3.3 Trapa natans (A) mature plants (B) flower (C) and (D) overview of invasion by the species in Wular lake, Kashmir
3.4 Azolla cristata (A) mature plants (B) sporangia (C) and (D) overview of invasion by the species in Wular lake, Kashmir.
3.5 Macrophyte sampling locations in Wular Lake during 2008 and 2011. 3.6 Surface details of Azolla cristata sporangia with SEM. (A) Megaspore perine surface is variously granular. (B) Massulae with glochidia mainly located on one side of surface. (C) The perine surface is reticulate with filaments. (D) The number of septa in glochidia range from 5-7. Scale bar- 20 [im (B,D); 10 [im (A); 2 urn (C).
3.7 Mean abundance ±SE of 15 most abundant macrophytes in Wular lake in 2008 and 2011. Bars capped by the same letter are not statistically different (p>0.05).
3.8 Overall mean abundance ±SE of the selected invasive macrophytes in Wular Lake during 2008 and 2011. Bars capped by the same letter are not significantly different.
3.9 Relationship between the Shannon-Wiener Diversity Index (H') and Alternanthera philoxeroides abundance in Wular Lake (A) overall abundance of macrophytes (B) Rooted floating macrophytes (C) Emergent macrophytes (D) Free floating macrophytes and (E) submerged macrophytes.
3 10 Spatial and temporal variations in water depth at the selected sites in Wular Lake during 2008 and 2011; (a) plot of means: the longest horizontal line represents overall mean whereas smaller horizontal lines on the vertical bar of season represents mean depths in different seasons (b) box plot of seasonal means and (c) of sites, (d) Tukeys HSD plot of site means (95% confidence level). Box length is the interquartile range, whiskers give 95% confidence limits and open circles denote extreme values.
3.11 The box-plot of mean seasonal and mean site variation of different water parameters at the selected sites in Wular lake during 2008 and 2011. The dark line in the box is median value whereas the length of the box shows the variability; longer the box, more the variability. 3.12 The box-plot of mean seasonal variation of different water parameters at the selected sites in Wular lake during 2008 and 2011. The dark line in the box is median values whereas the length of the box shows the variability; longer the box, more the variability. 3.13 Plot of means and box plot of seasonal means of ammonical nitrogen (a, b) and nitrate nitrogen (c, d) at the selected sites in Wular Lake during 2008 and 2011. The longest horizontal line in figure 'a' and 'c' represents overall mean whereas, the horizontal lines on the vertical bars represents mean concentration. Box length is the interquartile range, whiskers give 95% confidence limits and open circles denote extreme values.
3.14 Plot of means and box plot of seasonal means of orthophosphate phosphorous (a, b) and total phosphorous (c, d) at the selected sites in Wular Lake during 2008 and 2011. The longest horizontal line in figure 'a' and 'c' represents overall mean whereas, the horizontal lines on the vertical bars represents mean concentration. Box length is the interquartile range, whiskers give 95% confidence limits and open circles denote extreme values. 3.15 Box plots of seasonal variations in the sediment characteristics of Wular lake during 2008 and 2011 (Au=autumn, Sp=spring, Su=summer and Wi=winter). The dark line in the box is median values whereas the length of the box shows the variability; longer the box, more the variability. 3.16 Box plots of variations in the sediment characteristics at the selected sites in Wular lake during 2008 and 2011 (Au=autumn, Sp=spring, Su=summer and Wi=winter). The dark line in the box is median values whereas the length of the box shows the variability; longer the box, more the variability.
3.17 Mean (±SD) values of different nutrients in the selected species. 3.18 Canonical correspondence analysis ordination plot of macrophyte abundance accounting for 88.7%) and 93.8%) inertia in the abundance of species with respect to various environmental variables at Wular lake in spring 2008 and 2011 respectively. Species are indicated by triangles and environmental variables by vectors and are positioned according to biplot scores.
3.19 Canonical correspondence analysis ordination plot of macrophyte abundance accounting for 81.2% and 70.6%o inertia in the abundance of species with respect to various environmental variables at Wular lake in summer 2008 and 2011 respectively.
3.20 Canonical correspondence analysis ordination plot of macrophyte abundance accounting for 87.2% and 95.6% inertia in the abundance of species with respect to various environmental variables at Wular lake in autumn 2008 and 2011 respectively.
3.21 Overall canonical correspondence analysis ordination plot of macrophyte abundance accounting for 84.1% and 75.8% inertia in the abundance of species with respect to various environmental variables at Wular lake in 2008 and 2011 respectively.
IV 4.1 Distribution and increase in number and size of ^4. philoxeroides patches in Wular Lake from 2008-2011. 4.2 Evolution of the individual A. philoxeroides patches as a function of time. The time evolution of the four patches (of different mean area) is plotted. As the lake surface is covered up, the rate of growth for each of the patches decrease and for ? '• 0, it approaches steady state, as expected. 4.3 The fractional area of the Wular lake that is covered by A. philoxeroides as predicted by the numerical model. The fraction of the lake area covered by weed is plotted against time. The critical epoch To; defined as the time since 2008 it takes for the weed to cover 90% of the lake surface is also marked. The solid curve corresponds to the best-fit parameters of the growth rate of weed patches of various sizes as determined from the observations. The shaded area corresponds to the uncertainty in the determination in the parameters, which translates to the error bar on the prediction of TV- We predict that the lake area will be covered by weed between 13 and 19 years.
4.4 The fractional area of the Wular lake that is covered by A. philoxeroides as predicted by the numerical model by taking the first three years data to determine the model parameters and using the fourth year data as a test sample. In this case, the model parameters are poorly determined compared to the case where all four years of observation are used.
4.5 Alligator weed forms large floating islands in the lake. 4.6 A patch of alligator weed has settled on the lake sediment in winter season and locals use it as a support on the marsh littoral area of the lake. 4.7 Dense roots protect the young buds at the nodes in alligator weed during the extreme chilly winters in Wular lake, Kashmir.
4.8 Alligator weed spreading in the terrestrial areas along the shoreline in 2011. 5.1 Current distribution of Trapa natans in Wular Lake. 5.2 Approximate distribution of Trapa natans in Wular Lake in 1960's. 5.3 The box-plot of monthly variations in characteristics of Trapa natans in Wular lake. Box length is the interquartile range; whiskers give 95% confidence limits and open circles denote extreme values.
5.4 Site wise mean monthly values of different parameters of the Trapa natans in Wular Lake. Rosette diameter, area per leaf and leaf number per rosette are of primary rosettes.
5.5 Mean number of rosettes (per sq m) in Trapa natans at different depths in Wular lake.
5.6 Fruit number per rosette in Trapa natans from July to August in Wular Lake.
5.7 Trapa natans near its peak biomass in July 2010 at station I.
5.8 Decomposing Trapa natans at the same station, November 2010.
5.9 Trapa natans forms very large rosettes at S3.
5.10 A rosette at site S3 with 44 leaves and 43 cm rosette diameter. 6.1 Nymphoides peltata along the eastern side of Wular lake in June. 6.2 Same location of Wular Lake in December. N. peltata overwinters by forming short overwintering rhizomes which get buried under the sediment. 6.3 Quadrats of standard size were used to count the number of short overwintering rhizomes in the sediment. 6.4 Collection of hibernating short overwintering rhizomes along with the sediment from Wular lake, for plantation in ponds for in vitro pollination experiments. 6.5 A short hibernating rhizome anchored in the sediment by roots resumes growth and produces new leaves in the following spring at the same site. 6.6 N. peltata is harvested in large quantities by the locals for use as fodder.
6.7 Distribution map of Nymphoides peltata in Wular lake.
6.8 Location and floral morph proportions of the Nymphoides peltata populations surveyed during the present study in different lakes of Kashmir. g ^ Variations in the number of short overwintering rhizomes produced in the selected lakes in Kashmir (mean ± SD). 6.10 Fruit set following controlled intermorph, intramorph and self pollinations in N. peltata. The mean and SD are from the pooled data of 6 populations used in the experiment.
6.11 The influence of floral morph ratios (frequency of the L morph) on mean per cent fruit set (±SD) in the experimental population of Nymphoides peltata (a) total fruit set of flowers of the pin morph type; (b) total fruit set of flowers of the thrum morph type.
6.12 The results of the reciprocal cross wherein the pin morph when it acted as a female produced almost double number of seeds than when thrum morph acted as a female.
VI Freshwater is an essential resource for human life and well-being. Some major problems that humanity is facing in the twenty-first century are related to water quantity and/or water quality issues (UNESCO 2009). Freshwater's are among the most extensively altered ecosystems on Earth. Their transformations include changes in the morphology of rivers and lakes, hydrology, nutrient biogeochemistry and toxic substances, ecosystem metabolism and the storage of carbon, loss of native species, expansion of invasive species, and disease emergence. The major driving forces behind these transformations are changes in climate, hydrologic flow, land-use, chemical inputs and invasive species (Carpenter et al, 2011; Polasky et al., 2011). Protecting the world's freshwater resources requires sustainable management of pre determined threats over a broad range of scales extending from local to global levels (Vorosmarty et al., 2010). Freshwater constitutes only 2.5% of all freely available water on earth's surface, of which only 0.3% is readily accessible in lakes, reservoirs and rivers (Kalff, 2001). Freshwater ecosystems tend to have a higher portion of species threatened with extinction than their marine or terrestrial counterparts (Loh et al, 2005; Revenga et al., 2005; Dudgeon et al., 2006; Strayer and Dudgeon, 2010). Freshwaters worldwide have been heavily invaded by alien species (USGS 2008; Strayer, 2010) and are one of the major threats to their biodiversity (Jenkins, 2003; Dudgeon et al., 2006; Ricciardi, 2007).
1.1 ALIEN SPECIES AND THE INVASION PROCESS
Alien species (synonyms: adventive, exotic, foreign, introduced, non- indigenous, non- native) in any region are the result of anthropogenic activities that enables them to overcome fundamental biogeographical barriers (i.e. human-mediated extra-range dispersal) (Richardson et al., 2011). An alien species becomes invasive when it sustains self-replacing populations over several life cycles and spreads to a considerable distance from its site of introduction (Richardson et al., 2000, 2011). Alien species have been classified as casual, naturalized or invasive based on their status within the naturalization - invasion continuum (Richardson et al., 2000b; Pysek et al., 2004). A considerable development of understanding of the process of biological invasions achieved during the past two decades (Cadotte, 2006; Lockwood et al, 2007; Blackburn, 2009; Davis, 2009; Richardson, 2011) is the result of a large number of hypotheses (reviewed by Hierro et al., 2005; Inderjit et al., 2005; Richardson and Pysek, 2006; Catford et al., 2008; Bauer, 2012), fast accumulating syntheses (Drake et al, 1989; Pysek et al., 1995; Williamson, 1996; Mack et al., 2000; Perrings et al., 2000; Inderjh et al, 2005; Mooney et al., 2005; Cadotte et al, 2006; Barney and Whitlow, 2008) and management practices (McNeely et al., 2001; Wittenberg and Cock, 2001; Ruiz and Carlton, 2003; Batish et al., 2004; Hulme, 2006). The foundation of invasion biology as a new discipline has been laid by Charles Elton through his remarkable work, The Ecology of Invasions by Animals and Plants (Richardson and Pysek, 2008).
Biological invasions are a global phenomenon which threatens biodiversity and few ecosystems may be free from alien species (Catford et al., 2012). Biological invasions by non-native species have become a major environmental problem and a focus of ecological research. It is a muhistage process involving transport of propagules from native to a new range, followed by their introduction, establishment and spread in the new habhat (Theoharides and Dukes, 2007; Hulme et al., 2008; Richardson et al., 2011). Only a fraction of introduced species successfully establish or invade in the new region (Caley et al, 2008). Success or failure to establish depends on their ability of dealing with the new environment, whether they are able to reproduce, disperse, and successfully compete with resident biota in local communities (Pysek and Richardson, 2007; Kleunen et al., 2010), and also on the habitat and climate match between the native and invaded region and on the invasibility of recipient communities. Therefore, successful invasion requires that species arrive, establish, reproduce, spread and integrate with indigenous component species of the community (Richardson et al., 2000). Introduced alien species that sustain self-replacing populations for several life cycles or a given period of time without direct intervention by people, or despite human intervention is said to be established (Richardson et al., 2000; Pysek et al, 2004). A significant proportion of the introduced species may fail to establish their population in wild mainly due to multitude of biotic and abiotic factors. The tens rule - a probabilistic assessment of the proportion of species that reach particular stages in the naturalization - invasion continuum, predicts that 10% of imported species (species brought in for cultivation or held in captivity) become casual, 10% of casuals become naturalized and 10% of naturalized species become pests (Williamson and Brown, 1986; Williamson and Fitter, 1996). Biological invasions operate on a global scale and commercial trade propels the rates of annual and cumulative invasion due to the development of new source and recipient regions, trade routes, and markets, as well as new products, larger and faster ships, and increased air transport (Meyerson and Mooney, 2007). The frequent biological invasions due to their movement by humans beyond natural dispersal barriers (Weber et al., 2008) into a range of new habitats alter fundamental ecosystem processes (Dyer and Rice, 1999), cause heavy economic losses (Pimentel et al., 2005), exert novel selective pressure on both the introduced species as well as the species they interact with in the new environment (Suarez and Tsutsui, 2008), and threaten native biodiversity (Sala et al., 2000; Rabitsch and Ess), 2006; Sundaram and Hiremath, 2012).
Aquatic invasive species have altered the physical, chemical, and ecological conditions of freshwater ecosystems, and they are one of the two most important factors threatening aquatic ecosystems and biodiversity (Wilcove et al, 1998). Biological invasions are one of the main factors responsible for the imperilled status of freshwater ecosystems (Simon and Townsend, 2003; Kovalenko et al., 2010). Compounding these threats are the predicted global impacts of climate change leading to temperature changes and shifts in precipitation and runoff patterns (Dudgeon et al., 2006; IPCC 2007; Trolle et al., 2011). Besides, major changes in land use, water management and infrastructure development are lowering the condition of freshwater ecosystems and, by association, hindering food production, harming human health, increasing societal conflict, and limiting economic development (Ashton, 2002; MEA 2005; UNDP 2007). The altered biodiversity can severely impair the life-sustaining ecosystem services which in turn can adversely jeopardize the human welfare (Pejchar and Mooney, 2009). The extent of biological invasions has increased over the past half century (Pysek and Richardson, 2010; MEA 2005; McNeeley et al, 2001; Pysek et al., 2006), resulting in decline of ecosystem services as people have transformed ecosystems for the production of food, fuels and fibers (Dobson et al., 2006; Charles and Dukes, 2008). The Millennium Ecosystem Assessment recognized biological invasions as one of the five major causes of declines of biodiversity, which translates into reduced ecosystem services (MEA 2005).
In an attempt to unite the field of invasion biology, wherein a lack of consensus on the invasion framework exists due to varied approaches adopted along different taxonomic and environmental lines, Blackburn et al., (2011) proposed a unified framework that can be applied to all human-mediated invasions. This framework divides invasion process into a series of stages and identifies barriers in each stage that need to be overcome for a species or a population to pass on to the next stage (Figure 1.1). Most likely, a specific trait or a set of traits associated with invasive species largely promotes invasiveness at a particular stage, or in some cases more than one stage, but disproportionately along the continuum of invasion process. The stages in this model mirror the series of steps involved in the actual process of biological invasion and species can fail to become invasive at any of the stages identified because of a failure to breach any of the barriers to progress between stages.
1.2 REVIEW OF SPECIES INVASIVE TRAITS
The geographical origin of invasive plant may influence their invasiveness in new area (Reichard, 2001; Lloret et al., 2004). Species from large continent may more easily invade a new habitat where the climate is similar to their geographical origin, as compared to species from a small continent and in new habitat having a different climate (Sax and Brown, 2000; Mihulka and Pysek, 2001; Van Kleunen et al., 2007). A number of studies have highlighted that the wide distribution range of species in its native geographic region can be a reliable predictor of invasion success in non-native ranges (Scott and Panetta, 1993; Rejmanek, 1995; Goodwin et al., 1999; McKinney and La Store, 2007). Species vary in their natural range of distribution across different taxonomic groups. As expected, the widespread species may also have a higher overall chance of transport to non-native ranges as they are more likely to come into human contact (Goodwin et al., 1999; Cadotte et al., 2006). Hence, traits which allow a species to be widespread in the native range possibly favour its successful invasion in the non-native range (Booth et al., 2003; Kuhn et al, 2004). In a recent study Hejda et al., (2009) concluded that (a) casual species (species which do not form self- reproducing populations in the invaded region and whose persistence depends on repeated introductions of propagules) recruit from a wider range of habitats in their native range than they occupy in the invaded range, (b) the naturalized species (species which sustain self-reproducing populations without direct intervention by people) inhabit a comparable spectrum of habitats in both ranges, (c) the invasive species (subset of naturalized species that produce reproductive offspring, often in very large numbers, at considerable distances from the parent plants and which have the potential to spread over large areas) occupy a wider range of habitats in the invaded than in the native range.
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Stage Transport Introduction Establish ment Spread
^
Barrier
Boom and butt'
Management Prevention Containment Mitigation Eradication
Figure 1.1: The unified framework for biological invasions. The alphanumeric codes associated with the arrows relate to the categorization of species with respect to the invasion pathway. 'A' refers to potential invasive species in the native range. 'Bl* and 'B3' refers to Individuals transported beyond limits of native range in captivity or quarantine, in cultivation or directly released into novel environments respectively. 'CO' refers to individuals which fail to survive in introduced range. Individuals survive in the wild but fail to reproduce 'CI', reproduce but fail to produce self sustaining populations 'C2' or may produce self sustaining populations 'C3'. Populations which disperse 'Dl & D2' become invasive 'E'. (Courtesy: Blackburn et al.,2011). Climatic simulation models can be effectively used to evaluate the potential invasive species (Kriticos and Randall, 2001; Kriticos et al., 2003; Thuiller et al., 2005; Richardson and Thuiller, 2007). Julien et al, (1995) used CLIMEX model (which is mainly based on comparison of climates in a species native and probable non-native ranges) to predict areas suitable for growth of Alternanthera philoxeroides elsewhere in the world based on its known distribution in South and North America. Results indicated that most eastern and southern areas of continental Australia, eastern Asia, Africa and Europe are suitable for its growth. The results also indicated that control of alligator weed by the flea beetle {Agasicles hygrophila) would be restricted compared to areas at risk of invasion by this weed.
Alien species possessing a rich genetic diversity (higher number of infra- specific taxa in the native range) contributes to successful invasion of non-native ranges because the chance of pre-adapted genotypes of the species for post- introduction evolutionary success greatly increases (Blossey and Notzold, 1995; Muller-Scharer et al., 2004; Pysek et al., 2004).
Taxonomic affiliation or phylogenetic relatedness of a taxon, can provide important leads in the understanding and prediction of biological invasions. The potential existence of phylogenetic patterns in invasiveness has been recognized since the time of Darwin, (1859) with the notion that naturalization is more likely for aliens with no close relatives in the new land, due to lack of competitive exclusion (Darwin's naturalization hypothesis) (Daehler, 2001). Recent works of Cavender- Bares et al., (2004) on the phylogenetic patterns in biological invasions revealed phylogenetic clustering (non-native species are more closely related to native species than expected) as well as phylogenetic overdispersion (non-native species are less closely related to native species than expected). The phylogenetic patterns in biological invasions change depending on the spatial and taxonomic scale as different mechanistic processes operate at different scales (Swenson et al, 2006). Among angiosperms, Amaranthaceae, Brassicaceae, Convolvulaceae, Malvaceae, Poaceae, Papaveraceae and Polygonaceae have relatively higher proportions of alien invasive species (Weber, 1997; Daehler, 1998; Pysek, 1998; Wu et al., 2004; Khuroo et al, 2007). Likewise, aquatic angiosperm families, such as Alismataceae, Hydrocharitaceae, Nymphaeaceae, Potamogetonaceae and Typhaceae (Daehler, 1998) include world's worst invasives.
The invasion success has been attributed to superiority of the invasive species in terms of genome size, phenotypic plasticity, reproductive capabilities, seed dispersal mechanism, seedlings establishment and survivorship (Daehler, 2003; Rejmanek et al, 2005; Pysek and Richardson, 2007; Hulme, 2008). Invasion success can be constrained by the availability of dispersal agent(s) that must transport the species or its propagules to a non-native region. Alien invasive species (AIS) are transported to non-native regions by various dispersal agents or vectors (Benvenuti, 2007; Kowarik and Von der Lippe, 2007). Some common vectors associated with the transport of AIS include humans (Crosby, 1986; Kowarik and Von der Lippe, 2007), vehicles (Von der Lippe and Kowarik, 2007), wind (Nathan et al., 2002), water, birds (Gosper et al., 2005), frugivores (Buckley et al., 2006), and animals (Herrera, 1989; Cronk and Fuller, 1995). Presently, at the global scale, species transfer through human agency is much more frequent, efficient and effective than through other natural means and has no parallel in the evolutionary history (Elton, 1958; Mack et al., 2000; Vermeij, 1991; Ricciardi, 2007; Mack et al., 2000; Reichard and White 2001; Kowarik and Von der Lippe, 2007; Meyerson and Mooney, 2007; Wilson et al., 2009). Changes in the mode of travel and transport have greatly enhanced the survival prospects of both deliberately and accidentally introduced species. Information on the functioning and effectiveness of different pathways is therefore necessary to set priorities in regulation or management of biological invasions (Mack, 2003; Wilson et al., 2009).
Some invasive plants possess characteristics that increase the likelihood of their transport by specific vectors (Davies and Sheley, 2007). Adhesion of the adhesive seeds of invasive plants to animals and humans also has the potential in long distance dispersal of invasive plants (Cousens and Mortimer, 1995; Cousens et al., 2008; Sorensen, 1986). As humans are believed to be the primary dispersers of potential invasive species (Vermeij, 2005; Ricciardi, 2007), plants possessing traits that make them successfully introduced species, such as cold hardiness, disease resistance and showy flowers may lend them a higher overall chance of transport (Mack and Lonsdale, 2001). A number of studies have shown that plant introductions for the ornamental purpose are much more predominant (Groves, 1998; Pysek et al., 2002; Forman, 2003; Dehnen-Schmutz et al., 2007 a, b; Khuroo et al, 2007).
Invasive macrophytes have evolved different adaptive mechanisms which improve their survival and the dispersal. Phenotypic plasticity exhibited by many invasive macrophytes allows them to develop growth forms that suit particular envirormiental conditions and revert to another form when conditions change (Mitschell and Gopal, 1991). For example, Salvinia molesta has three main growth forms. In newly invaded localities Salvinia molesta has an invading form consisting of leaves about one cm wide that float on water surface. When the plant becomes crowded the leaves become keeled and assume a boat shape (Mitschell, 1970). Similarly, Eichhornia crassipes also has a series of growth forms best suited for different situations.
In order to understand the success of an invader in a non-native region, it is important to integrate information about the introduction patterns, such as the distribution and intensity of introduction events, both in space and time (Vila and Pujadas, 2001; Mack and Emeberg, 2002; Leung et al., 2004; Lambdon and Hulme, 2005). Demographic, environmental and other stochastic factors may operate to reduce the population size and cause invasion failure. But, repeated introductions of a species that increases its population number and even spatially distribute the population may help to overcome the consequences of stochasticity (Reaser et al., 2008). The high propagule pressure may be necessary in locations with intense competition or harsh abiotic conditions (D'Antonio et al., 2001; Foster et al, 2004; Lockwood et al., 2005) so that the species is distributed patchily in such a way that all the members in any age class are not affected equally by environmental perturbations. Propagule pressure is defined as the amount, frequency, and timing of reproductive material reaching a new area and disseminating within it and across different spatial scales. It is believed to be a critical factor in naturalization and broad-scale establishment of alien species (Kolar and Lodge, 2001; Lockwood et al., 2005; Von HoUe and Simberloff, 2005; Pauchard and Shea, 2006; Wilson et al, 2007; Reaser et al., 2008). Nontheless, the potential for spatial patchiness to function as a buffer against extinctions caused by environmental stochasticity depends on the degree to which environmental fluctuations are correlated across patches (Gilpin, 1987; Stacey and Taper, 1992). Therefore, if known beforehand, the initial distribution of the populations of invasive species across a spatial hierarchy can be used to predict its potential for spread.
Riis et al. (2010) observed that phenotypic plasticity (ability of plants to rapidly change their phenotypic characters in relation to the environmental conditions in the habitat) enabled the clonally reproducing macrophytes Egeria densa, Elodea canadensis and Lagarosiphon major to adapt to a wide range of habitats in introduced areas. Geng et al, (2007) used molecular markers to explain the success of Alternanthera philoxeroides to colonize a wide range of habitats. The resuhs strongly support phenotypic plasticity rather than locally adapted ecotypes, which allows alligator weed to adapt in a wide range of habitats in China. In this study, any evidence of genetic diversity among populations from different habitats was not recorded. Phenotypic plasticity is especially important for aquatic plant species which often spread asexually and thus lack genetic variation. Daehler, (2003) reviewed the studies comparing phenotypic plasticity of alien invasive species and native species and concluded that AIS are generally more plastic. Richards et al., (2006) however, emphasized that the plasticity of traits is unlikely to have any appreciable effect on species invasiveness unless it contributes to fitness.
In many aquatic plants, clonal integration has been reported to enhance the survival in new regions. Xu et al., (2010) studied the effects of clonal integration on the gro^^^h and phylogeny of invasive herbs Alternanthera philoxeroides and Phyla canescens. The results revealed that clonal integration facilitates nitrogen assimilation and promotes the opportunistic expansion of these invaders on site scale.
Comparative studies have shown that alien invasive species have higher relative growth rates than their native counterparts (Baruch et al., 1989; Pattison et al, 1998). For example, extra-ordinary growth rate of Eichornia crassipes has been recorded in many countries with an increase in biomass of 400-700 tons per ha per day (Ruiz et al., 2008). The great morphological plasticity of the Eichornia crassipes coupled with its wide ecological amplitude allows a high growth rate over a long period and provides water hyacinth a competitive advantage over other free floating macrophytes. Relative growth rate represents an expression of different aspects of plant morphology, anatomy and physiology (Grotkopp et al., 2002). Several studies have suggested higher specific leaf area values of invasive exotics may also contribute to their success as invasive species (Hamilton et al., 2005; Lake and Leishman, 2004).
Allelopathy has been demonstrated in many aquatic plants. Allelopathy is an important attribute of a plant which helps reduce competition by inhibiting the germination and growth of co-existing plant species (Schenk et al., 1999; Callaway and Aschehoug, 2000; Inderjit and Callaway, 2003; Inderjit et al, 2005). Although the case for allelopathy in wetland invasive species is weaker, some phytotoxic compounds have been isolated in several Typha species (Gallardo et al., 1998, 2002), Alternanthera philoxeroides (Wu et al., 2006), Eichornia crassipes (Sun et al., 1988; Shanab et al., 2010). Schultz and Dibble, (2012) reviewed how the invasive macrophyte species impact fishes and macroinvertebrates identified allelopathy as one of the factors responsible for negative effects on fish and macroinvertebrate communities.
Reproductive strategy of alien species is crucial not only during the initial introduction phase but also during the final stage of widespread occurrence of alien species in non-native habitats (Daehler and Strong, 1994, 1996; Rejmanek and Richardson, 1996; Pysek, 1997; Grotkopp et al, 2002). The trade-off between 'sexual' vs. 'vegetative' strategies is a crucial determinant of the success of alien plant invasions (Eckert et al., 2003; Brown and Eckert, 2005; Lui et al., 2005). While as the clonal propagation promotes rapid and unlimited propagation of favourable genotype recombinants, perpetuation of sterile genotypes, rapid colonization of favourable habitats, potenfially unlimited lifespan, and reparthion of clone exfinction risks (Silander, 1985), the sexual reproduction confers advantage of generating wide genotypic diversity which increases the ability of a species to adapt to changing environments (Mandak et al., 2005).
Xu et al. (2003) reported extremely low genetic diversity in invasive Alternanthera philoxeroides in China and concluded that its rapid range expansion was most likely the result of massive clonal propagafion since its introduction. In fact many studies of invasive clonal aquatics have revealed very low levels of diversity in the introduced range as a result of founder effects and restrictions on sexual reproduction (e.g. Laushman, 1993; Barrett et al, 1993; HoUingsworth and Bailey, 2000; Kliber and Eckert, 2005; Wang et al, 2005).
10 Zhang et al. (2010) studied genetic diversity at global scale in a highly clonal invasive flowering plant Eichhornia crassipes (water hyacinth). The results largely showed genetic uniformity in the introduced regions indicating that E. crassipes probably owes its invasive success to the possession of several key life-history traits, including the high dispersal of floating propagules, prolific clonal reproduction and well-developed phenotypic plasticity. Shifts to asexual propagation have occurred in several clonal invaders because of the absence of sexual partners in the introduced range (e.g. Elodea canadensis, Sculthorpe, 1967; Fallopia japonica, HoUingsworth and Bailey, 2000; Oxalis pes-caprae, Omduff, 1987). Hybridization and polyploidization may confer enhanced invasiveness if a hybrids exhibits traits that are novel to those of either parent line, formed because of transgressive segregation; or hybridization leads to adaptive trait introgression, in which alleles that could potentially increase fitness or fecundity are transferred from one species to another (Prentis et al., 2008). However, it needs to be borne in mind that the role of hybridization in promotion of plant invasions, in turn, depends upon a variety of genetic and ecological factors, such as the strength of reproductive barriers that isolate the hybridizing taxa, vigour and fertility of hybrids, relative and absolute sizes of hybridizing populations, demographic stochasticity, population growth rates, diversity of self-incompatibility alleles, and changes in herbivore and pathogen pressure (Wolf et al., 2000).
1.3 THE IMPACT OF INVASIVE MACROPHYTES
Macrophytes are key components in aquatic ecosystems because they influence nutrient cycling, fuel aquatic food webs, provide physical structure, and in particular, affect various organisms like invertebrates, fishes and waterbirds by increasing habitat complexity in waterscapes (Wetzel, 2001). Aquatic macrophytes play an important role in structuring communities in aquatic environments. The high biodiversity of freshwater ecosystems (9.5% of the total number of species, Balian et al., 2008) may be explained in part by the presence of macrophytes, which increase habitat complexity at different spatial scales in littoral zones and have positive effects on the taxonomic (Vieira et al, 2007; Pelicice et al., 2008) and functional diversity (Heino, 2008) of other assemblages. Macrophytes have an established position in a shallow lake, where they persist and dominate by having access to nutrients in the
11 sediment and mechanisms of storing scarce nutrients by recycling them back to roots and rhizomes in winter (Carignan and Kalff, 1980; Esteves and Camargo, 1986; Camargo et al., 2003). Aquatic plants directly influence the hydrology and sediment dynamics of freshwater ecosystems through their effects on water flow (Madsen et al., 2001) and particle trapping or re-suspension (Vermaat et al., 2000). Aquatic plants have been aggregated into four functional groups or life forms (Sculthorpe, 1967; Cronk and Fermessy, 2001; Lacoul and Freedman, 2006):
• emergent species are rooted in bottom substrate but the plant extends above the water surface; they mostly occur in shallow water and include species of sedges and bulrush Cyperaceae), rushes (Junceae), grasses (Poaceae), cattails (Typhaceae), and others. • floating-leaved are rooted in sediment but have leaves that float on the water surface; they may occur at moderate depths and may be prominent in low- visibility water, and include species of lotus (Nelumbonaceae) and water lily (Nymphaeaceae). • submerged plants are usually rooted in bottom substrate, but may be free- floating, and their foliage is normally underwater; they occur at various depths and include species of water-starwort (Callitrichaceae), water-milfoil (Haloragaceae), pondweed (Potamogetonaceae), and elodea, wild celery, and frogbit (Hydrocharitaceae). • free-floating hydrophytes float on the water surface but do not have roots embedded in sediment; they freely move with wind and water currents, and include species of water-lettuce (Araceae), mosquito-fern (Azollaceae), water hyacinth (Pontederiaceae), and duckweed and watermeal (Lemnaceae).
Aquatic macrophytes as invasive species are widely recorded in the scientific literature (e.g., International Union for Conservation of Nature 2003; Michelan et al., 2010; Thomaz et al., 2009; Barrientos and Allen, 2008; Bickel and Closs, 2008; Douglas and O'connor, 2003; Kelly and Hawes, 2005; Strayer et al., 2003). Invasive macrophytes have been shown to cause local extinctions of native species, and alter ecosystem processes such as nutrient cycling, hydrology, and plant productivity in their new environment (Vitousek et al., 1996; Pimentel et al., 2000). Invasive macrophytes cause significant changes in food web structure and trophic dynamics of
12 invaded ecosystems (Wilcove et al, 1998; Wetzel, 2001; D'Antonio and Hobbie, 2005; Carvalheiro et al., 2010). Invasion of Eurasian watermilfoil {Myriophyllum spicatum L.) increased trophic diversity in invaded lakes in USA (Kovalenko and Dibble, 2011). Invasive macrophytes affect the resident fauna associated with native macrophyte communities by altering habitat, epiphyton production and nutrient cycling (Carpenter and Lodge, 1986; Jeppesen et al., 1997) which in turn can result in change in their trophic position as well (Hoeinghaus et al., 2008). Aquatic invasive species have altered the physical, chemical, and ecological conditions of freshwater ecosystems, and are one of the two most important factors threatening aquatic ecosystems and biodiversity (Wilcove et al., 1998).
Michelan et al. (2010) studied effects of an exotic invasive macrophyte - tropical signalgrass (Urochloa subquadripara) on native plant community composition, species richness and functional diversity. They did sampling at fine scale using a (Im x 1 m) quadrat. The results showed a negative effect on macrophyte richness and Shannon and functional diversity, and also influenced assemblage composition. Emergent, rooted with floating stems and rooted submersed species were negatively affected by tropical signalgrass, while the occurrence of free-floating species was posifively affected. Thomaz and Michelan, (2011) while working on tropical signalgrass, demonstrated that spatial scale of the study affects the patterns of association among the non-native and individual native species. They also inferred from the results that phylogeny did not explain associations between the invasive and native macrophytes.
Bassett et al. (2011) observed that Alternanthera philoxeroides altered insect community composition and abundance compared with native sedges around a New Zealand lake. It was found to decompose more rapidly than two New Zealand native species, thus altering patterns of nutrient cycling (Bassett et al., 2010). A. philoxeroides shows increased evapotranspiration compared with open water and over native floatingspecies , resulting in water loss in infested areas (Boyd, 1987; Allen et al., 1997).
Klein and Verlaque (2009) investigated the variation of the macrophyte assemblage associated with an invasive macrophyte Caulerpa racemosa in the bay of Marseilles, France. The results showed that the associated assemblage showed
13 significantly lower numbers of species, lower cover of native and introduced macrophytes and lower diversity (Shannon diversity index and Pielou's evenness) compared to the non-invaded assemblage. They also observed that the cover of other invasive macrophytes was greatly reduced in the invaded assemblage, indicating strong competitive interactions between C. racemosa and the other invasive species.
Zhonghua et al. (2007) studied the intraspecific and interspecific interference abilities of two floating leaved aquatic plants Nymphoides peltata and Trapa bispinosa. They observed that N. peltata exerted a strong interspecific interferential effect on T. bispinosa, but the opposite was not apparent. Also the intraspecific interferential effect of T. bispinosa on itself, although the interspecific interference of N. peltata was stronger.
Klein and Verlaque (2009) investigated the variation of the macrophyte assemblage associated with the invasive marine macrophyte Caulerpa racemosa var. cylindracea in the bay of Marseilles, France. The results showed that When C. racemosa var. cylindracea was present, the associated assemblage showed significantly lower numbers of species, lower cover of native and introduced macrophytes and lower diversity (Shannon diversity index and Pielou's evenness) compared to the non-invaded assemblage.
1.4 SOCIO-ECONOMIC IMPACTS OF AQUATIC MACROPHYTE INVASIONS
Invasive macrophytes can have very serious socio-economic effects and these are generally exacerbated by the unexpected appearance of the species when it first invades and subsequently by its rapid growth (e.g., Pimentel et al., 2000; Lovell, Stone and Fernandez, 2006; Keller et al., 2009). Invasive macrophytes interfere with water and fishery production, with commercial, industrial and even recreation activities. Because invasive species alter the structure and function of ecosystems, they have large impacts on the quality and quantity of services provided (MEA 2005, Lodge et al. 2006, Pejchar and Mooney 2009). Eradication of Eichhornia crassipes in the Guadiana river in Spain has cost 6.7 M€ in one year (Andreu et al., 2009). A meta-analysis of 89 wetland valuation studies (excluding climate regulation and tourism) by Schuyt and Brander (2004) indicated that the global annual value of
14 wetlands is $70 billion, with an average annual value of $3000/ha/year and a median annual value of $150/ha/year. In the United States alone aquatic invasion associated damages and costs of controlling them are estimated at $9 billion annually (Pimentel, 2003).
An extreme example of adverse impact of the invasion of an alien aquatic weed occurred in the 1970's-1980's when thick mats of floating Salvinia molesta covered approximately 80 kilometers of the Sepik River and 90% of Chambri Lake in Papua New Guinea. This prevented villagers from fishing or traveling from their homes to gather and trade food or go to medical clinics. The infestation was eventually brought under control by the release of a tiny weevil as a biological control agent (Mitchell, 1979; Mitchell and Gopal, 1991). In less developed countries, where people depend on their waterways for subsistence fishing, transportation, and drinking water, aquatic weeds can be life threatening.
1.5 ABIOTIC FACTORS AND MACROPHYTE INVASIONS
The invasion success of an invasive macrophyte involves a combination of environmental factors and plants performance (Maurer and Zedler, 2002; Hastwell et al, 2008). Identifying the factors associated with the success of invasive species is helpful in predicting its invasion and controlling such species and to elucidate the interaction between invasive and native species in ecosystems (Pysek and Richardson, 2007; Funk 2008; Xie et al., 2010). A number of invasive macrophytes, including water hyacinth (Eichhornia crassipes), Eurasian watermilfoil (Myriophyllum spicatum), water chestnut (Trapa natans), and hydrilla {Hydrilla verticillata), have been found to change important aspects of freshwater systems in North America (Smith and Barko, 1990; Kiviat, 1993; Langeland, 1996; Urban et al., 2006). An increase in the abundance or area occupied by invasive macrophyte can be an indicator of environmental degradation (Kennard et al., 2005).
Yu and Yu (2011) studied the responses of the floating-leaved invasive aquatic plant Nymphoides peltata to gradual versus rapid increases in water levels. The capacity for petiole elongation was dependent on leaf age, and only leaves that were no more than five days old had the capability to reach the water surface when the water level increased rapidly from 50cm to 300 cm. They observed that continual
15 leaf recruitment and rapid petiole elongation were both important ways in which N. peltata adapted to increasing water levels. Dense mats oiN. peltata also lower the amount of oxygen in the water (Nature Serve, 2008). Smits et al., (1992) reported that leaf development of Nymphoides peltata could only take place if sufficient calcium was available in the water layer. They also concluded that the restricted occurrence of Nymphoides peltata to well-buffered alkaline waters is functionally more related to the calcium availability than to the bicarbonate content. Nymphoides peltata is almost completely absent from poorly-buffered waters and is never found in acid water bodies. Nymphoides peltatahas the potential to colonize large areas within one growing season by means of vegetative propagation (Brock et al., 1983), and a single plant can produce over 100 new plants in only 12 weeks (Zhonghua et al., 2007). N. peltata is declared a noxious weed in New Zealand and parts of North America (NWCB, 2007), and is also declared as invasive in Sweden (Gren et al., 2007). It is a known invasive species in Kashmir as well (Khuroo et al., 2007).
Tao et al. (2009) investigated the structural adaptations of aerial parts of invasive Alternanthera philoxeroides to water regime. They observed that the cuticular wax layer, coilenchyma cell wall, phloem fibre cell wall and hair density on both leaf surfaces thickened significantly with decrease of water availability and played important role when switching from flooding to wet and then to drought habitats. These responsive variables contributed most to the adaptation of Alternanthera philoxeroides to diverse habitats with varying water availability. Wang et al., (2005) reported that even small fragments of alligator weed are readily established and spread in novel environments. Many floating aquatic weeds like Eichhornia crassipes and Alternanthera philoxeroides form floating mats intercepting light entering aquatic environments. The production of submerged macrophytes and algae is thus reduced under low light conditions, which in turn effects the aquatic community composition and food web structure (Villamagna and Murphy, 2010). In Italy, the floating mats of Trapa natans block light transmission to only 7% with less algal biomass and macroinvertebrate species (Cattaneo et al., 1998).
Environmental factors are critical in determining community structure (Mony et al, 2007; Michelan et al, 2010). Zutshi and Gopal, (1990) reported that among several factors which contribute to the species richness of macrophytic community,
16 water depth and its periodic fluctuation are probably important ones for submerged and emergent ones. In a recent study, Mormul et al., (2012) concluded that water brownification (browning of inland waters due to increase in concentrations of dissolved organic matter of terrestrial origin) may increase the invisibility of invasive species by impairing growth of native macrophytes. Pertinent to mention is that there is an increasing trend of water browning in Northern Hemisphere and is expected to have far reaching ecological and societal consequences as it is bound to affect the structure and function of the aquatic ecosystem, e.g. through the impaired light climate, and reduce the recreational value and potential to use the water as a drinking water resource (Chow et al, 2007; Monteith et al., 2007; Kritzberg and Ekstrom, 2012).
Caraco and Cole (2002) studied the impact of native and invasive macrophytes on dissolved oxygen in Hudson River. The partial replacement of native water celery {Vallisneria americana) by much denser beds of introduced water chestnut (Trapa natans) increased frequency and extent of low dissolved oxygen episodes, with probable substantial impacts on fish and invertebrates. Goodwin et al., (2008) reported that hypoxic conditions (DO < 2.5 mg L"') occurred frequently at the tidal Hudson River with dense coverage by an invasive floating leaved plant {Trapa natans). Pierobon et al., (2010) also reported reduced dissolved oxygen concentration under dense canopy of Trapa natans.
Xie et al. (2010) investigated the differences in asexual propagation between introduced exotic and non-invasive native aquatic macrophytes in nutrient-poor and nutrient-rich sediments. They used three exotic aquatic macrophytes {Elodea nuttalUi, Myriophyllum aquaticum, and M. propinquum) recently introduced to China and their non-invasive native counterparts {Hydrilla verticillata, M. oguraense, and M. ussuriense). The exotic species tended to produce more total biomass, branch biomass and apical shoots and have higher relative growth rate (RGR) than their native counterparts in nutrient-rich sediment. These results suggest that asexual propagation of these three introduced exotic macrophytes is more effective in nutrient-rich sediment than in nutrient-poor sediment in China.
Quinn et al. (2011) while studying the effects of land use and environment on alien and native macrophytes concluded that there are inherent differences in the
17 ability of native and aliens even of the same life-form to capitalize on anthropogenic disturbance. They also observed that habitats that receive nutrient pollutants and that occur in urban and agricultural areas low in the catchment are invasion susceptible.
Kors et al. (2012) studied the temporal changes and the environmental factors governing the composition and distribution of macrophyte communities in an unregulated rivers. The CCA results revealed that year was a statistically important parameter for determining the composition of macrophyte community. The hydrological parameters (discharge, water level and water temperature) and some hydrochemical parameters like conductivity, dissolved oxygen and sulphate content were significant in determining the distribution of macrophytes. Bini et al (1999) while studying the distribution of macrophytes in relation to water and sediment in Brazil concluded that for floating macrophytes nutrients in both sediment and water were important while as for submerged weeds light penetration turned out to be strongest predictor.
O'Hare et al. (2012) studied the relative impacts of spatial, local environmental and habitat connectivity on the structure of aquatic macrophyte communities in lakes. The results identified total phosphorus, alkalinity/conductivity and the presence of invasive species as the key drivers of observed variation in macrophyte communities in conservation lakes. They concluded that because of the spatial aggregation of environmental and connectivity factors, the traditional catchment approach was insufficient in lake management and suggested a landscape scale approach should be used. Capers et al. (2011) also observed pH, conductivity, water clarity, lake area and maximum depth as important variables affecting plant community structure of lakes.
1.6 STUDIES ON INVASIVE MACROPHYTES IN INDIA
Aquatic weeds are a major problem in India like many other parts of the world but unfortunately have not received enough attention from the ecological perspective to enable an understanding of their nature and relationships with environmental variables. Most of the studies have highlighted weedy nature of aquatic vegetation and emphasis has been given on control measures rather than on ecological significance. Overall information on vegetation is scanty. Studies on aquatic plant
18 invaders are inadequate, scattered and disorganized leaving large information gaps on their current and potential distribution (Shah and Reshi, 2011). Although problems related to macrophyte invasions have been noted throughout India, a national strategy on Invasive alien plants is lacking. Aquatic weeds threaten our water bodies by enhancing the rate of evaporation and consequently reduce the availability of water. It has been estimated that 20-25% of the total utilisable water in India is currently infested with water hyacinth (Eichhornia crassipes), while in the states of Assam, West Bengal, Orissa and Bihar, it was 40% (Gopal and Sharma, 1981; Sushilkumar, 2011).
Aquatic weeds are widely distributed in India (Gupta, 1987, Phogat, 1996, Bhan and Sushilkumar, 1996, Mathur et al, 2005, Varshney et al, 2008; Sushilkumar, 2011). In India the total number of aquatic plants species exceeds 1200 (Gopal, 1995). A total of 160 aquatic plants have been documented as invasive, of which the following weeds have been identified of primary concern: Eichhornia crassipes, Salvinia molesta, Alternanthera philoxeroides, Nymphaea stellata, Nelumbo nucifera, Hydrilla verticillata, Vallisneria spiralis, Typha angustata, Chara spp., Nitella spp., Ipomoea spp. (Sushilkumar, 2011). More recently, Alternanthera philoxeroides has been identified as a growing menace in the waterbodies in India (Sushilkumar et al., 2009). Rivers irrigation canals, lakes, ponds are choked by the explosive growth of aquatic weeds in India, resulting in enormous direct losses. Ecological studies on vegetation, particularly on relationship of abiotic factors with biomass and primary productivity, have been conducted in some aquatic habitats of Kashmir (Kaul et al., 1980; Trisal and Kaul, 1983; Kaul and Zutshi, 1966; Kaul and Vass, 1972; Kaul, 1977; Kaul et al., 1978; Zutshi, 1975; Zutshi and Vass, 1976).
Kaul et al. (1976) suggested that shrinking of the Kashmir lakes was mostly attributable to the profusion of aquatic plant growth, which may have resulted from increased water pollution. They noted that under favorable conditions water chestnut quickly forms a stable floating mat, which hinders navigation and interferes with recreational activities in Kashmir (Kaul et al., 1976). A large area of Dal Lake towards Saderbal side has been turned into marsh supported by thick mats of Typha and Phragmites and subsequently into land mass (Adnan and Kundanagar, 2009, Kundanagar, 2010). A significant change in the vegetation patterns of Dal lake have
19 been triggered by the invasive species for example Azolla in Dal lake (Adnan and Kundanagar, 2009). They have attributed the prolific growth of this species to unabated inflow of effluents, raw sewage and enrichment of the lake sediments particularly due to heavy load of organic nitrogen and phosphates, which is also threatening several species like Euryaleferox.
Pandit (2002) concluded that obnoxious spread of Lemna-Salvinia weed complex in some Kashmir lakes overwhelmed the native vegetation and restricted the growth of submerged species. The authors reported a decline in the production of Nelumbo nucifera on account of invasion by Salvinia nutans. Pertinent to mention is that in India, S. natans is invasive in Kashmir only (Varshney et al., 2008).
Ganie et al. (2008) observed that the invasion success of Potomogeton crispus in freshwater ecosystems of Kashmir is attributed to its multiple reproductive strategies. In running waters, rhizomes and nodal plantlets of meristematic branches constitute the dominant mode of reproduction. Amphimixis and vegetative propagules viz. turions are favored reproductive strategies in lakes and other lentic water bodies. In fact, multiple reproductive strategies have been reported in a number of invasive plants, such as Elodea canadensis (Sculthorpe, 1967), Eichornia crassipes (Barrett, 1992), Fallopia japonica (Hollingsworth and Bailey, 2000), Butomus umbellatus (Lui et al, 2005).
Reshi et al. (2008) have identified a total of 133 plant species belonging to 66 genera and36 families constituting the alien flora of lakes and wetlands. They obser^'ed that species with emergent life forms are predominant in comparison to rooted floating leaf types and submersed types. The most common invasive plant species in Kashmir are Sparganium erectum, Typha angustifolia and Phragmites australis (rooted emergent life form), Nymphoides peltata, Trapa natans and Potamogeton nodosus (rooted floating leaf type habit), Potamogeton crispus and Myriophyllum-Ceratophyllum complex (submersed growth habit) and Lemna- Salvinia-Azolla complex (free-floating life form).
20 OBJECTIVES
The present study was conducted on four invasive macrophytes viz., Trapa natans (Linn.), (Lythraceae), Nymphoides peltata (S.G.Gmel.) (Menyanthaceae), Alternanthera philoxeroides (Mart.) Griseb, (Amaranthaceae) and Azolla cristata Kaulf. (Azollaceae) in Wular Lake. While T. natans and N. peltata are widespread in distribution and form abundant populations in the region, Azolla cristata and A. philoxeroides are recent introductions in the lake. The specific objectives of the present study were:
• To document the macrophytic species composition and abundance in Wular lake over a temporal scale; • Distribution mapping of the selected invasive macrophytes using conventional survey and Geographic Information System (GIS) techniques; • To analyze the physicochemical characteristics of water and sediment governing the distribution and abundance of the selected macrophytes. • To study the growth and spread dynamics of Trapa natans; • To study the reproductive biology of Nymphoides peltata.
To achieve the above objectives, the study was designed involving periodic field visits and laboratory analysis. The selected species differ in their habit, so it was difficult to have a common approach for their study. Species specific parameters were analyzed during this study.
21 2.1. LOCATION AND EXTENT
Wular Lake and associated wetlands form a part of River Jhelum basin, which is a sub-basin of Indus River. The basin is bowl shaped forming an elongated depression between the great Himalayas in the north east and the Pir Panjal ranges in the south west. Wetlands of Jhelum basin are mainly of three different types with respect to their origin, altitudinal situation and the nature of biota:
I. The glacial upper mountain oligotrophic lakes situated in the inner Himalayas between 3000 - 4000 m amsl altitude have probably originated during the third Himalayan glaciations. II. The lakes of tectonic origin (Nilnag), being mesotrophic and present in the lower fringes of pir panjal range at an altitudinal range of 2000 - 2800 m amsl. III. The eutrophic valley lakes (Dal, Anchar, Manasbal, Wular, Trigam, Tilwan etc) which are of fluviatile origin are situated in the low lying areas at an altitudinal zone of 1560 - 1600 m amsl. Mostly valley lakes occur all along the flood plains of the river Jhelum.
All these wetlands are basically high altitude wetlands as compared to those located in the plains of India (altitude <500m amsl) and are longitudinally and altitudinally intercoimected.
Wular Lake is the largest freshwater lake in India with an area of 11,277 hectares (NWA 2010). Wular Lake is located in the valley of Kashmir, the northern part of India (Figure 2.1). It is 34 km northwest of Srinagar, the state capital, at an altitude of 1580m asl between 34°16'N and 34°25'N latitude and 74°29' E and 74°40'E longitude (NWA 2010). It is elliptical in shape with a maximum length of 16 Km and breadth of 9.6 Km. Wular Lake is of open drainage type with permanent inflow and outflov^ channels. Most of the tributaries of Jhelum originate from glaciated lakes and regulate the base flow of the river. River Jhelum originates from Pir-Panjal range near Verinag. After passing through the city of Srinagar, it merges into Wular Lake and pursues upto Baramulla and finally into Pakistan. River Jhelum is joined by Lidder, Harwan, Sindh,, Erin, Madhumati and Pohru rivers on its right while the left bank is joined by Sandran, Vishav, Rambiara, Dudganga and Sukhnag rivers (Map 2.2). The
22 water extent of lake varies seasonally and is lowest in winter (Map 3.3). The water level increases rapidly from February depending on the rates of precipitation.
2.2. IMPORTANCE OF THE LAKE
Wular Lake plays a significant role in the hydrography of Kashmir valley by acting as a huge absorption basin for floodwaters. The lake provides livelihoods to a population of 10,964 households in 31 villages along the shoreline (Table 2.1; Figure 2.3). The local government earns revenue by issuing licences for harvesting the resources from the lake chiefly fish, waterchestnut and fodder species. It also provides important habitats for migratory water birds within Central Asian Flyway. The lake was included in 1986 as a Wetland of National Importance under the Wetlands Program of the Ministry of Environment and Forests, Government of India for intensive conservation and management purposes. Later it was designated as a Wetland of International Importance under Ramsar Convention in 1990 because of its importance to the biodiversity and socio economic values. More recently Wular Lake and associated marshes viz., Haigam, Hokersar, Mirgund and Shallabug have been included in the network of Important Bird Areas.
2.3. CLIMATE
Climate of the region is marked by well-defined seasonality and resembles that of sub- Mediterrarian type (Bagnolus and Meher-Homji, 1959). The temperature ranges from an average daily maximum of 3l''C and minimum of 15°C during summer to an average daily maximum of 4*'C and minimum of - 4''C during winter. It receives annual precipitation of about 1,050 mm mostly in the form of snow during the winter months. On the basis of temperature and precipitation, a year in the valley is divisible into following four seasons:
I. Spring season (March- May) II. Summer season (June-August) III. Autumn season (September-November) IV. Winter season (December-February)
23 2.4. GEOLOGY
Wular Lake is surrounded by Pir Panjal mountain range in South-West and Higher Himalayas in the North-East. The Panjal Traps and limestones form the major source rocks for the sediments which drain into the lake through rivers and streams, namely Jhelum River, Madumati and Erin streams. Due to degraded catchment and quarrying in the vicinity of the lake, physical weathering dominated over chemical weathering resulting in enhanced rates of erosion and consequent deposition of huge detritus into the lake. The degraded direct catchment area besides entire basin of river Jhelum contributes to heavy loads of silt into Wular leading to the shrinkage of its breadth and depth.
2.5. DESCRIPTION OF STUDY SITES
Due to large shoreline and difficult approach, we identified 6 sites for sampling. Only one site could be covered in a day.
Site 1 (SI)
Station 1 covers the western side of the lake. A large area at this station along Sopore- Watlab section has been brought under paddy and willow cultivation. There is a navy base camp located on a hill bordering this station. All the sewage from the navy camp and villages flow directly into the lake. This station largely has rooted floating vegetation and to some extent submerged vegetation. A patch of Phragmites australis has established recently and is expanding fast. There are two fish-landing centers established by the state government fisheries department at this station.
Site 2 (S2)
This station is on the southern side of the lake. River Jhelum exits Wular lake at this station. There is a river (Haritar Nallah) that joins the lake in this zone. Besides another river (Ningli nallah) also joins river Jhelum at the terminal end of the lake, but does not directly flow into the lake. Two villages are located along the shoreline of this zone. Massive plantation of Willow has taken place in the lake area. Hundreds of cattle and sheep are seen grazing along the littorals at this station and as the water levels start decreasing from autumn to winter, they keep moving deep inside the lake.
24 Two fish landing centres are also located in this zone. There are apple orchards and paddy fields adjacent to this zone and pesticides are used extensively.
Site 3 (S3)
On the eastern and southern side of the lake are the low lying areas of Sonav/ari which used to get flooded every year. Construction of flood protection embankments along this side has resulted in fragmentation of the wetland regimes and consequently shrinkage of Wular Lake. This zone has undergone extensive siltation over the decades marked by an inward shift of the littoral zone. Trapa natans followed by Nymphoides peltata occur widely at this station occupying different depths of the lake. Among all the stations in the lake, submerged macrophytes are most abundant at this station. Marshy areas of this zone have been lost to willow plantation over the decades. There is a heavy drawdown at this station and sediment of a large area remains exposed during late autumn and winter seasons.
Site 4 (S4)
This station has extensive human settlements and sewage from the entire population directly flows into the lake. In this zone, paddy fields are directly in touch with lake waters. Besides the sewage and detergents from households directly makes way into the lake, resulting in increased eutrophication of the lake. There are three fish landing centers in Kehnusa, Ashtangoo and Laharwalpur villages on shoreline of this zone. Nelumbo nucifera, once growing luxuriantly in the lake has now remained confined to small patches at this station.
Site 5 (S5)
This station is on the northern side of the lake and sewage pollution of a large population of Bandipora town and adjoining villages flows directly into the lake. Madhumati nallah flow into Wular lake at this site. This zone is surrounded by salix plantation on three sides and has undergone extensive siltation. Herds of cattle manage to make their way in this zone and are seen grazing. This zone has lost a major portion of its fishing habitat. On the north-eastern part of this zone, the sand collected from the lake is gathered and loaded in trucks.
25 Site 6 (S6)
This zone is surrounded by salix plantation on all the four sides. Larger portion of this zone has turned into a marsh. River Erin joins the lake in this zone. There are two fish landing centers in this zone, one in Lankreshpura and another in Kulhama villages. This zone is cut off from rest of the lake by the extensive salix plantation and siltation. A major portion of this zone has turned into a marsh.
WULARLAKE
3 0 3 Kilometers
Figure 2.1: Location map of Wular Lake
26 N A
/\/ River Jhelum / V Rivers •• Wular lal Figure 2.2: Wular Lake within Jhelum basin (modified after wetlands international 2007). 27 Table 2.1: Demographic features of the settlements around Wular Lake and Resource Hnkages (as per 2001 Census) S.No Village name Households Population Resource linkage 1 Adipora 368 2927 Fish and fodder 2 Janwara 216 2160 Fish and fodder 3 Hathlung 105 528 Fish and fodder 4 Watlab 258 1878 Fish, Trapa and fodder 5 Bangladesh 48 344 Fish and Trapa 6 Zurimanz 52 270 Fish and Trapa 7 Kehnusa 22 164 Fish, Trapa and fodder 8 Kanibathi 66 728 Fish, Trapa, fodder and lotus 9 Ashtangoo 43 340 Fish, Trapa and fodder 10 Badyari 27 256 Fish, Trapa and fodder 11 Aloosa ghat 70 780 Fish, Trapa and fodder 12 Pahribal 78 417 Fish, Trapa and fodder 13 Kemah 277 1631 Fish, Trapa and fodder 14 Mangreypora 411 2460 Fish, Trapa and fodder 15 Laharwalpur 412 3258 Fish, Trapa and fodder 16 Garoora 328 2454 Fish, Trapa, fodder and lotus 17 Saderkoot payeen 30 233 Fish, Trapa and fodder 18 Sogam wudar 20 184 Fish, Trapa and fodder 19 Kulhama 149 1123 Fish, Trapa and fodder 20 Lankreshipur 20 216 Fish, Trapa and fodder 21 Ajas 1415 9870 Fish, Trapa and fodder 22 Banyari 432 3204 Fish, Trapa and fodder 23 Makhdomyari 609 4982 Fish, Trapa and fodder 24 Madwan 15 175 Fish, Trapa and fodder 25 Rakh hajin 268 1982 Fish, Trapa and fodder 26 Hajin Ghat 15 92 Fish, Trapa and fodder 27 Hajin 1159 9972 Fish, Trapa and fodder 28 Zelwan 20 184 Fish, Trapa and fodder 29 Gundjahangir 299 2909 Fish, Trapa and fodder 30 Bakshi Bal 50 347 Fish, Trapa and fodder 31 Shahgund 705 5537 Fish, Trapa and fodder 28 N .^ A / Kemah '§/ Aloosa ghat * M'-'^-^Banyari ^/ Mangreypora Ashtangoo^yi*^ ^ ,f ^^^l^P ^^--^Sogam Wudar Kanibathi • f LankreshR|«l^^^^j J • 'WKulhamak^derkoot Payeen Kehnusa* \ f \ -—^ yW Lahawalpur ZurJmanzp Bangladesfi Watlab • f ^ / Malhdanuri V Hathiung«^V jMpMadwan ^ ^«4i* Hajjn Ghat 1 ^ ^^^A • Hajjn \ % Janwara/^ ^^^ Rakh Haiin J ^ Adipora* A ^HW •Shahgund y V • Gutxijahangir |v« Badyarj Pahribal ^akshi bal • Settlements 3 0 3 •1 Salix plantation Kilometers 1 1 Wular Lake Figure 2.3: Human settlements along the shore line of Wular Lake. 29 CHAPTERS TEMPORAL CHANGES IN THE COMPOSITION OF MACROPHYTE COMMUNITIES AND ENVIRONMENTAL FACTORS GOVERNING THE DISTRIBUTION OF SELECTED INVASIVE MACROPHYTES IN WULAR LAKli:, KASHMIR, INDIA Ather Masoodi and Fareed A. Khan (2012). Invasion of an alien species Altemanthera philoxeroides in Wular Lake, Kashmir, India. Aquatic Invasions 7 (1): 143-146 Masoodi, A; Khan, F.A., (2012). A new record to the invasive alien Flora of India- Azolla cristata. National Academy Science Letters 35 (6), 493-495 Shaik A. Rashid, Ather Masoodi. Fareed A. Khan (2013). Sediment-water interaction at higher altitudes: Example from the geochemistry of Wular Lake sediments, Kashmir valley, northern India. Procedia Earth and Planetary Science 7, 786 - 789. SUMMARY In the present research conducted in Wular lake during 2008 and 2011, change in abundance of macrophytic flora in the lake on the spatial and temporal scale was studied. In the present study, the main focus was to understand which environmental factors govern the distribution of four invasive macrophytes viz., Alternanthera philoxeroides, Azolla cristata, Nymphoides peltata and Trapa natans. A total of 33 macrophytes, belonging to four life forms (Emergents, rooted floating, submerged and free floating) were recorded in the present study. Trapa natans, Nymphoides peltata and Azolla cristata were the most dominant in terms of abundance and distributed widely throughout the lake. Results reveal that the invasion of Alternanthera philoxeroides has decreased the overall diversity of the lake with a selective impact on different life forms. According to CCA, Alternanthera philoxeroides utilised the resources differentially at temporal scale so as to get the best of what is available, this gives an edge to this species to increase in abundance and thereby effective area occupied within the lake. Results from our study point out that Alternanthera philoxeroides is a potentially emerging invasive species in the Wular Lake and posing a significant threat to aquatic biodiversity through its fast expansion. We warrant an urgent need for checking further spread A. philoxeroides and consistent monitoring of its expansion pattern in space and time might give more clues regarding hs effective management. Keywords: Alternanthera philoxeroides. Species composition, CCA, Wular lake, Ramsar site. 30 3.1 INTRODUCTION Macrophytes are the large macroscopic aquatic plants found in lakes and ponds as opposed to the smaller and microphytic algae or phytoplankton (Gushing and Allan, 2001). Aquatic macrophytes have been categorized into four classes viz., emergents, submerged, floating-leaved and free floating. Each group has unique characteristics and functional role in aquatic ecosystems (Carpenter and Lodge, 1986; Jeppesen et al., 1998; Chambers et al., 2008; O'Hare, et al., 2012). The composition and abundance of macrophytes in the littoral zone (the extent of aquatic plant cover in a pond or lake) can be influenced by numerous factors including sediments, wind, water clarity and nutrients (Lyon, 2007; Madsen and Cedergree, 2002; Schneider and Melzer, 2004; Baldy et al., 2007; Kors et al., 2012). The abundance and diversity of macrophytes are important indicators of the ecological status of shallow lakes and are widely used as metrics for site-condition monitoring (Hunter et al, 2010). The European Union Water Framework Directive (EUWFD) (2000/60/EC) also uses macrophytes as one of the biological quality elements for the assessment of ecological status in surface waters (Penning et al., 2008). The abundance and composition of the macrophyte community has a significant effect on a lake ecosystem, especially for shallow lakes (Carpenter and Lodge, 1986; Blindow et al., 1998). Macrophyte composition at any site is the result of multifactorial influence of historical, environmental and biological factors (Johnson et al., 1993). Many shallow lakes are thought to alternate between a clear and a turbid state (Scheffer et al., 1993). Shallow lakes that support abundant submerged vegetation when the water is clear might be degraded by excessive inputs of nutrients from sewage effluent, agriculture or internal loading caused by the excretion and foraging activities of fish (Hansel et al., 2003). Interaction among species (both positive and negative) can shape community structure and composition (Bertness and Callaway, 1994; Stachowicz 2001; Bruno et al., 2003; Schultz and Dibble, 2012; Wundrow et al, 2012). For instance, facilitative or mutualistic interactions of exotic species with native species may lead to their invasion (Richardson et al., 2000), stimulate invasion of other species (Ricciardi, 2001) or even decrease chances of future invasions (Mack et al., 2000). Introduced plants become invasive in new 31 habitats on availability of niche opportunities, which includes natural enemy escape and resource availability (Shea and Chesson, 2002; Schooler et al, 2007). Monitoring of the changes in community composition induced through invasive species over time has relevance for developing predictive models. The introduction of non-native species poses threats to the integrity and functioning of ecosystems. Invasive macrophytes lead to local extinctions of native species, and alter ecosystem processes such as nutrient cycling, hydrology, and plant productivity in invaded ecosystems (Vitousek et al., 1996; Pimentel et al, 2000). Invasive species are notorious for their tendency of altering species richness within invaded communities (Rejmanek and Rosen, 1992; Hager and McCoy, 1998; Parker et al., 1999; Meiners et al, 2001; Thaisa, 2010). Such an invasion in a New York lake by the aquatic herb Myriophyllum spicatum reduced species richness from 20 to just 7 native species within 11 years due to dense canopy formation and overshadowing of native species (Boylen et al., 1999). Eradication of alien species and restoration of habitats becomes almost after the alien species gets established (D'Antonio and Meyerson, 2002; Ewel and Putz, 2004, Edwards and Taylor, 2008; Strayer, 2010). ft is widely agreed that preventing biological invasions or tackling them at a very early stage is the most efficient and cost-effective approach (European Environment Agency, 2013). Aquatic weeds are a major problem to the health of lakes and wetlands in Kashmir. In all 133 plant species belonging to 66 genera and 36 families constitute the alien flora of lakes and wetlands in the Kashmir Valley (Reshi et al, 2008). Available literature suggest that significant work has been done on the invasive macrophytes worldwide (Barrat-Segretain, 2001; Strayer et al., 2003; International Union for Conservation of Nature, 2003; Douglas and O'connor, 2003; Finlayson, 2005; Kelly and Hawes, 2005; Ali and Soltan, 2006; Mony et al, 2007; Daniel and Rydin, 2008; Barrientos and Allen, 2008; Bickel and Closs, 2008; Thomaz et al., 2009; Michelan et al., 2010; Thaisa, 2010), but little work has been done in the Indian context and especially in high altitude lakes. Keeping in view the ecological importance of freshwater systems, there is keen interest in characterizing the influence of non-native species on the abundance and distribution of both native and non-native macrophytes. The present study 32 evaluated the composition and abundance of macrophytic community in the lake and to more specifically to test whether Alternanthera philoxeroides abundance is affecting the community composition of the lake at temporal scale. The present study was aimed at study the influence of various environmental factors in on the distribution of the selected invasive macrophytes in the Lake. The study is first of its type from India involving the monitoring of an invasive macrophyte immediately after it was first recorded in an aquatic ecosystem. 3.2 MATERIAL AND METHODS The study was carried out during 2008 and 2011. Sampling of water, sediment and macrophytes was done seasonally during spring, summer, autumn and winter seasons at the selected sites (Chapter 2; Map 2.1). Spring sampling was between April 10 and April 25, summer sampling between July 10 and August 10, autumn sampling between October 10 and October 25 and winter sampling between January 10 and January 25 each year. For identification of any unknown plant species, 2 or 3 specimen of each species were collected. The collected specimens were pressed in between blotters of field press and light pressure was applied. The specimens were pressed as per standaird herbarium procedures and preserved for future reference. Macrophytes were identified with the help of standard taxonomic works (Fasset, 1998; Kak, 1990; Cook, 1990) and by expert verification of un-identidied samples (personal communication with Dr A. M. Kak, Research Coordinator ICSC Srinagar, Kashmir). The identification of Azolla cristata was ascertained by Prof. Charles Van Hove, with the help of Scanning electron micrographs of sporangia. Samples of Azolla with sporocarps attached were collected from multilple locations of Wular lake. Surface details of the sporangia especially the megaspore perine surface and glochidia septation, which are considered more reliable criterion were observed (Perkins et al., 1985; Pereira et al., 2000; Gardenal et al, 2007). Observations were made with the help of light microscope and Scanning Electron Microscope (SEM) Model ZEISS EVO-40EP. The spores were observed without any chemical treatment and put on double sided sticky tape on bronze stubs, and coated with gold. 33 3.2.1 Study Species Trapa nutans var. nutans Linn. Common names: European water chestnut, Water chestnut, Bull nut. Water nut, water caltrop Family: Lythraceae Description: A floating aquatic annual. Leaves are arranged in a rosette; 2-4 cm (0.75-1.5 in.) long. Upper leaves are slightly rhombic to rhombic-ovate, margins sharply dentate; petiole up to 10 cm long, dilated near the leaf base, villous. Lower surface with conspicuous veins and short, stiff hairs. Submerged lower leaves alternate and feather-like, up to 15 cm (6 in.) long. The inconspicuous white flowers are solitary and axillary and consist of four 8 mm (0.3 in.) long, white petals and four green sepals, 5 mm long, ovate, villous, especially in the middle portion. The fruit is a four-homed, all the angles of the fruh being spinescent, nut-like structure about 3 cm (1.2 in.) wide that develops underwater. Nymphoides peltata (S. G. Gmelin) Kuntze Common names: Yellow floating heart. Floating heart, Fringed water lily, water fringe (English), Asaza (Japanese), Entire marshwort (New Zealand), Xing cai (Chinese), Family: Menyanthaceae Description: Perennials with a long creeping rootstock. Stem long, floating, rooting at the nodes. Leaves floating, lamina more or less rounded or rarely orbicular with a cordate base, 2.5-5 (-11) cm x 2-6 cm with dense conspicuous dark glands on the under surface, margin entire or wavy, petiole (2-) 3-7 (-10) cm long. Flowers in an axillary fasciculate umbel, pedicels 5-7 cm long. Calyx 7-10 mm long, c.4 mm broad, nearly obtuse. Corolla 18-25 mm long, bright yellow, united almost one third with obovate emarginate lobes, finely and sparingly fringed. Anthers more or less enlarged in their lower part, 3-4 mm long, filaments bearded with 5 oblong, oval, ciliate appendages at the top. Stigma bilobed, style 4-5 mm long, ovary shorter than the style. Capsule ovoid, 18.25 mm long, acute; seeds ellipsoid, 4-6 mm x c.3 mm, winged. 34 Alternanthera philoxeroides (Mart.) Griseb. Common names: AUigatorweed, Pig Weed Family: Amaranthaceae Description: Perennial herb, stem ascending from a creeping base, 55-120 cm, branched; young stem and leaf axil white hairy; old ones glabrous. Petiole 3-10 mm, glabrous or slightly hairy; leaf blade oblong, oblong-obovate, or ovate-lanceolate, 2.5-5 x 0.7-2 cm, glabrous or ciliate, adaxially muricate, base attenuate, margin entire, apex acute or obtuse, with a mucro. Heads with a peduncle, solitary at leaf axil, globose, 0.8-1.5 cm in diam. Bracts and bracteoles white, 1-veined, apex acuminate; bracts ovate, 2-2.5 mm; bracteoles lanceolate, ca. 2 mm. Tepals white, shiny, oblong, 5-6 mm, glabrous, apex acute. Filaments 2.5-3 mm, connate into a cup at base; pseudostaminodes oblong-linear, ca. as long as stamens. Ovary obovoid, compressed, with short stalk. Fruit not known. Azolla cristata Kaulf. Family: Azollaceae Description: An aquatic fern with deeply bilobed leaves. It has a very thin and hyaline ventral leaf lobe and an aerial and chlorophyllous dorsal lobe, which have an extracellular cavity. It is characterized by overlapping scale-like leaves, covering a slender and branched stem (rhizome) that floats horizontally on the water surface with single or fasciculate pendulous roots. 3.2.2 Macrophyte sampling Macrophyte sampling in the lake was undertaken in three seasons viz., spring, summer and autumn at the selected sites during the study period. A floating (Im x Im) quadrat was used to record vegetation at the selected sites along many transects that best represented aquatic macrophyte composition. 15 quadrats were laid at each site making a total of 90 quadrats on each sampling occasion (Figure 3.1). Quadrats were laid starting from lake shore to the maximum depth of plant colonization and rated the abundance of plant species (rooted floating and emergents) present within the sample visually on a Domin-Krajina cover scale (1 = <20%; 2 = 21-40%; 3=41- 60%; 4 = 61-80%; 5 = 81-100% of covering), (Santos and Thomaz, 2008). For submerged species, a long-handled rake was used to measure the abundance within 35 these quadrats. The rake was 36 cm (14 inches) wide, has 14, 5 cm (2 inches) long teeth (Yin et al., 2000). The teeth were divided and marked into five equal parts (or 20% increments) and species were given a density rating based on their thickness on the rake teeth (1 = <20%; 2 = 21-40%; 3 = 41-60%; 4 = 61-80%; 5 - 81-100% of covering) (Yin et al., 2000). Due to a lack of specific landmarks, drift of the boat during sampling, and inherent inaccuracy of the GPS units, it was impossible to sample the exact same sites repeatedly in both the years. The percent cover of free floating Spirodella, Azolla and Lemna exceeding 5% was marked as 1. 3.2.3 Physical and chemical analysis of water Three replicates of water samples at approximately 20 cm depth were collected in acid-rinsed polyethylene bottles from predetermined sites. For the analysis of dissolved oxygen, the water sample was collected in a BOD bottle and care was taken to ensure that no air bubble was trapped inside the bottle. This water was then fixed with alkaline sodium iodide and manganous sulphate and transported in iceboxes to laboratory for analysis. Water samples were collected in 1 litre polyethylene bottles. Some of the parameters like temperature, conductivity, pH and transparency were determined on the spot; remaining parameters were analyzed in the laboratory within 48 hours of sampling following standard methods (APHA, 1998; Trivedy et al., 1998). Water depth was recorded by sounding the lake bottom using a standard lead weight (1kg) attached to the marked rope. Transparency of water was determined by using a standard Secchi disk (diameter 20 cm). The mean depth at which Secchi disk disappeared and reappeared was taken as water transparency. Temperature was measured using mercury-filled centigrade thermometer. The pH was measured on the site using pen type pH meter (Model Systronics-335). Before taking the reading, the pH meter was standardized with known buffer solutions of pH 7 and 9.2. Conductivity of water samples was measured with the help of digital conductivity meter (Model Systronics-611E). The conductivity meter was calibrated before use with standard potassium chloride solution (0.0IM) and the results were expressed in * 36 Figure 3.1 Nymphoides peltata (A) mature plants (B) flower and (C) overview of invasion by the species in Wular lake, Kashmir. 37 ^ " '^^^^Hl 1^ I * ^ (^Jltf-UM,-**^, ) D Figure 3.2 Alternanthera philoxeroides (A) mature plant (B) inflorescence (C) and (D) overview of invasion by the species in Wular Lake, Kashmir. 38 Figure 3.3 Trapa natans (A) mature plants (B) flower (C) and (D) overview of invasion by the species in Wular Lake, Kashmir. 39 •sf*^- Figure 3.4 Azolla cristata (A) mature plants (B) sporangia (C) and (D) overview of invasion by the species in Wular Lake, Kashmir. 40 if Bandipora A Kehnus, O Sampling locations m Saiix plantation Kilometers I I Wular Lake Figure 3.5: Macrophyte sampling locations in Wular Lake during 2008 and 2011. 41 Winkler's modified method (APHA, 1998) was used to estimate dissolved oxygen concentration. In the laboratory, the samples were treated with concentrated sulphuric acid to liberate the iodine equivalent to dissolved oxygen originally present. Exactly 100 ml of the sample was titrated against standard sodium thiosulphate solution of known normality (0.025N) using starch as indicator. The values were expressed in mg/L. Ammonical nitrogen was estimated by Nessler's method. To 25 ml of water sample, 1.5 ml of Nessler's reagent (100 g of mercuric iodide and 70 g of patassium iodide dissolved in distilled water and diluted to 1000 ml) and 0.5 ml of Signette's sah (20 g of potassium antimony tartirate tetrahydrate dissolved in 200 ml of distilled water and traces of mercuric chloride for preservation) were added. After 20 minutes, the yellow color developed and transmittance was measured at 420 nm with the help of a spectrophotometer (Model Systronics 116). Ammonium chloride was used for making standard curve. The results were expressed in |igL''. Nitrate nitrogen was estimated by Salicylate method (CSIR 1974). 100 ml of water sample was completely digested along with 1 ml of sodium salicylate. The digested residue was then dissolved in 1 ml concentrated H2SO4. 10 ml of distilled water was added careftiUy to the aliquot and then treated with 30% NaOH solution till the appearance of yellow color. After 15 minutes, absorbance was measured by the spectrophotometer (Model Systronics 116) at 490 nm. Standards were prepared from potassium nitrate and results expressed in p-gL"'. Calcium and magnesium were determined complexometrically by EDTA method. Sodium and potassium were determined by flame photometric method using flame photometer model AIMIL-106. The concentrations were deduced from their respective standard curves and expressed in mgL"'. Chloride was estimated by Argentometric titration method. The orthophosphate phosphorous concentration was estimated by Molybdenum blue method. To 50 ml of water sample, 40 ml of ammonium molybdate and 0.5 ml starmous chloride was added. The intensity of blue color developed was measured by a spectrophotometer after 10 minutes at 690 nm (Model Systronics 116). Potassium dihydrogen phosphate was used for making standards. The results were expressed in ^gL*. For the estimation of total phosphorous 50 ml of water sample 42 was digested with 3 ml nitric acid and 1 ml sulphuric acid on a hot plate till the volume was reduced to 3-5 ml. After this a few drops of phenolphthalene were added to the sample and titrated against 0.2N NaOH till light pink color appears. The sample was then raised to the original volume and to which 2 ml ammonium molybdate and 0.5 ml stannous chloride was added. The intensity of blue color developed was measure at 690 rmi with the help of a spectrophotometer. Potassium dihydrogen phosphate was used for making various standards and the results were expressed in UgL-'. 3.2.4 Sediment analysis Sediment samples were collected with the help of soil corer made of a PVC pipe (diameter 8 cm). Soil inside this corer was removed to a depth of 10 cm with help of a hand shovel and collected in polythene bags. Three replicates were taken from each site every time. The soil samples were sealed in polyethylene bags and brought to the laboratory. The sediment samples were dried in the oven at 105 C and stored in plastic boxes after grinding and sieving through 2 mm mesh sieve. pH was measure on the spot. 10 g fresh sediment was placed in a beaker and 25 ml of distilled water were added to it making a suspension of 1:2.5 w/v. Readings were taken with the help of a pen type digital pH meter (Gupta, 2004). The particle size distribution of sediment was determined by using sieves of different size to separate sand (2.0-0.02mm), silt (0.02-0.002mm) and clay (<0.002mm) particles after air drying the sediment (Head 1980). The samples from all the sites were analyzed for calcium, magnesium, potassium, sodium, nitrogen and phosphorous using SEIMENS SRS 3000 Sequential X-ray Spectrometer at the Wadia Institute of Himalayan Geology, Dehradun, India. 3.2.5 Chemical analysis of plant mineral nutrients Oven-dried sample powder (100 mg) was carefully transferred to a digestion tube and 2 ml of concentrated sulfuric acid was added to it. The contents of the flask were heated on a temperature controlled assembly for about 2 h. As a result, the contents of the tube turned black. It was cooled for about 15 min at room temperature and then 0.5 ml 30 % H2O2 was added drop by drop and the solution was heated again till the colour of the solution changed from black to light yellow. After further cooling 43 for about 30 min, additional 3 to 4 drops of 30 % H2O2 were added, followed by heating for another 15 min. It was repeated till the light yellow colour turned colourless. The digested material was transferred from the tube to a 100 ml volumetric flask with three washings by de-ionized water. The volume of the volumetric flask was then made up to the mark (100 ml) with de-ionized water. The aliquot was used for estimation of Ca, Mg, N, P and K content. Nitrogen was determined by the method of Lindner (1944) and phosphorus by the method of Fiske and Subba Row (1925). Potassium was determined using flame photometer following Hald (1947). Calcium and magnesium were determined by titrimetric method (Jackson 1967). 3.2.6 Statistical analysis Influence of seasons, sites and year on water chemistry and sediment chemistry were separately analyzed by oneway ANOVA. Differences in the water and sediment chemistry among the seasons and sites were tested by Tukey's HSD test (at P < 0.05). All statistical analyses were performed using the R statistical package. To investigate the factors causing variations in the water quality data and sediment data in Wular lake. Principal Component Analysis was employed. The analysis was carried out using statistical software SPSS 11.0 (SPSS Inc., 1999) for extraction and rotation of the principal components. Measure of association between different pairs of variables was estimated using the correlation matrix in order to eliminate the effect of difference in scales among the variables. The principal components have been extracted using the variance maximizing rotation and the number of factors determined using the Kaiser's criterion (Kaiser, 1958). The rotation of principal components has been done using the varimax rotation technique, which tends to eliminate medium range correlation between components and original variables. Frequency of each plant species on each occasion was calculated as the number of locations a plant was found divided by the total number of locations sampled. The abundance of each plant was derived by summing the abundance of each plant on each sampling occasion and dividing by the number of locations sampled (Gidudu et al., 2008). Mean abundance of each plant species for each year 44 were compared with analysis of variance (ANOVA) followed by Student-Newman- Keuls post-hoc means separation procedure when ANOVAs were significant. Canonical Correspondence Analysis (CCA; Ter Braak, 1986; Legendre and Legendre, 1998) performed using the CANOCO, version 4.5 (Ter Braak and Smilauer, 2002) was used to determine which, if any, of the environmental/physical variables, had a significant effect on the distribution of macrophytes within Wular Lake. The macrophyte abundance data matrix was analyzed by CCA using environmental data matrix separately for different seasons in order to examine the relationships between macrophyte abundance and environmental variables. In the CCA analysis length of the arrows (eigen vectors) indicate the degree of correlation between the species abundance and the environmental variables. The longer the arrow the stronger is the relationship of that particular environmental variable with species abundance. 3.3 RESULTS 3.3.1 Macrophytes In the present study a total of 33 species of macrophytes distributed over 27 genera and 22 families were recorded in Wular Lake (Table 3.1). Potamogetonaceae is the largest family with a single genus and 5 species. Alismataceae, Poaceae, Hydrocharitaceae, Nympheaceae and Lemnaceae are represented by two species each. The remaining families are represented by a single species. The macrophytes also included three pteridophytes viz. Azolla cristata Kaulf, Sahinia natans All and Marsilea quadrifolia L. belonging to the families AzoUaceae, Salviniaceae and Marsileaceae respectively. Eight of the species collected were not previously reported from Wular Lake, including Bidens cernua L., Lycopus europaeus L., Veronica anagallis-aquatica L., Alternanthera philoxeroides (Mart.) Griseb, Echinochloa crusgalU Beauv., Potomogeton pectinatus L., Scirpus lacustris L. and Vallisneria spiralis L. Of the macrophytes collected in the present study, 13 species belong to emergents, 7 to rooted floating, 8 to submerged and 5 to free floating class (Table 3.1). The mean abundance of macrophytes in year 2008 and 2011 are given in Table 3.2. The results reveal that Trapa natans, Nymphoides peltata, Azolla cristata. 45 Phragmites australis and Ceratophyllum demersum are the five most abundant species in the lake during 2008. In 2011, Alternanthera philoxeroides which ranked 15th in terms of abundance in 2008 replaced Ceratophyllum demersum as the fifth most abundant species in the lake. Azolla cristata was second most abundant species in 2011 replacing Nymphoides peltata. The results also reveal that many of the emergent species have gained on account of mean abundance where as almost all the submerged macrophytes are losers. There is a significant impact of seasons on the mean abundance of macrophytes in the lake (p<0.05). The most striking increase is in the abundance of Azolla cristata which increased to more than twice in autumn season. The other species showing a increase in abundance from summer to autumn season include Alternanthera philoxeroides, Phragmites australis, and Echinochloa crus-galU. The mean abundance (±SE) of 15 most abundant species, which constitute more than 90% of the total abundance in the lake is given in (Figure 3.7). Among the selected invasive macrophytes, the abundance of Alternanthera philoxeroides has increased significantly from a mean value of 0.72 ±0.28 in 2008 to 4.50 ±0.71 in year 2011 (p<0.05; Figure 3.8). The mean abundance of Azolla cristata also increased significantly from 6.50 ±0.85 in 2008 to 8.28 ±0.96 in 2011. The mean abundance of Trapa natans has decreased from 18.66 ±1.42 in 2008 to 16.17 ±1.34 in 2011 (p<0.05). The abundance of Nymphoides peltata did not show any statistically significant difference between two years. The results also reveal that among other species, Salvinia natans recorded a significant decline in abundance from a mean value of 1.17 ±0.36 in year 2008 to 0.67 ±0.27 in year 2011 (p<0.05). The most frequent species recorded in Wular lake were Trapa natans (66.67%), Azolla cristata (61.11%), Nymphoides peltata (37.78%), Phragmites australis (28%), Ceratophyllum demersum (22%), Potomogeton lucens (20%) and Hydrocharis dubia (17.78%). The frequency of Alternanthera philoxeroides increased from (3.7%) in year 2008 to (13%) in year 2011 and that of Azolla cristata increased from (42.2%) in year 2008 to (50.4%) in year 2011. There was no change in the frequency of Trapa natans and Nymphoides peltata during the study period. There was little variation in terms of species richness at the selected sites in the lake, but varied in terms of the number of species of different life forms. At SI, the total niunber of species was 15, which includes two emergents viz., Phragmites 46 australis and Alternanthera philoxeroides, 5 rooted floating species and 4 species each of submerged and free floating life forms. At S3, the total number of species was 14 with only one emergent species Alternanthera philoxeroides, and 7 submerged species. S5 also had a total of 14 species, but 10 species were of emergent type and only one species each of rooted floating and submerged life forms. S4 and S6 had 16 species each, and represented by all life forms. Figure 3.9 shows the relationship between Shaimon-Wiener diversity index at the selected sites and Alternanthera philoxeroides abundance in Wular Lake. Results reveal that there is a decrease in the overall diversity of macrophytes with a significant decrease in the diversity of free floating macrophytes (Figure 3.9). A declining trend is observed in the diversity of rooted floating and submerged macrophytes while as for emergent species the trend is positive. 3.3.2 Physico-chemical characteristics of water Temperature Water temperature followed the changes in air temperature throughout the year. The surface water temperature ranged from 2.5-29.5'^C in the lake during the study period (Table 3.3). Maximum temperature of 29.5°C was recorded at SI and S3 during summer 2008 and lowest temperature of 2.5°C was recorded in winter season at S5 in the same year (Table 3.4). The results reveal that variability in water temperature due to season is much higher with little variability between sites and year. All the pair-wise seasonal comparisons of mean temperatures are significantly different (p<0.05). The pair-wise comparisons of water temperature at sites revealed that only five pairs (S3 vs SI, S3 vs S2, S4 vs S3, S6 vs S5 and S5 vs S3) are significantly different (Table 3.4). 47 Table 3.1: List of macrophytes recorded from Wular Lake in the present study Reported from Plant Species Family Growth habit Reported from Kashmir lake Alisma plantago-aquatica I. Alismataceae Emergent Kaul (1986) Kak(1990) Alternanthera philoxeroides{MarX.) Griseb. Amaranthaceae Emergent Masoodi and Khan (2012a) No Azolla cristata Kaulf. Azollaceae Free floating Masoodiand Khan (2012b) Pandit etal (2005)* Bidens cernuo L Asteraceae Emergent Stewart (1972) No Ceratophyllum demersum L. Ceratophyllaceae Submerged Kak (1990) Kak(1990) Echinochloa crus-galli Beauv, Poaceae Emergent Kaul (1986) Pandit etal. (2005) Hydrilla verticillata Royle Hydrocharitaceae Submerged Kaul and Zutshi 1967 Pandit etal. (2005) Hydrocharis dubia Backer Hydrocharltaceae Free floating Kak(1990) Kak(1990) Lemna minor I. Lemnaceae Free floating Kaul (1986) Kak(1990) Lycopus europaeus L Lamiaceae Emergent Kaul (1986) No Marsilea quadrifolia L. Marsileaceae Rooted floating Reshi (1984) No Myriophyllum spicatum L. Haloragaceae Submerged Kaul and Zutshi 1967 Kak(1990) Myriophyllum verticillatum L Haloragaceae Emergent Kak(1990) Kak(1990) Nelumbo nucifero Gaertn. Nelumbonaceae Rooted floating Zutshi et al. (1980) Kak(1990) Nymphaeo tetragona Georgi. Nympheaceae Rooted floating Koul and Naqshi (1988) No Nymphea alba L. Nympheaceae Rooted floating Koul and Naqshi (1988) Kak(1990) Nymphoiodes peltate Kuntze, Menyanthaceae Rooted floating Kaul (1986) Kak (1990) Phragmites australis Trin. Poaceae Emergent Kaul (1986) Kak(1990) Polygonum amphibium L. Polygonaceae Emergent Kak(1990) Pandit etal. (2005) Potomogeton crispus L. Potamogetonaceae Submerged Kaul and Zutshi 1967 Pandit etal. (2005) Potomogeton lucens L. Potamogetonaceae Submerged Zutshi etal, (1980) Pandit etal. (2005) Potomogeton natans L. Potamogetonaceae Rooted floating Kak(1984) Kak (1990) Potomogeton pectinatus L. Potamogetonaceae Submerged Kak(1990) No Kundangar and Zutshi Potomogeton pusillus L, Potamogetonaceae Submerged (1987) Pandit etal. (2005) Saglttaria sagittifolia L. Alismataceae Emergent Reshi(1984) Kak(1990) Zutshi and Wanganeo Salvinia natans All. Salviniaceae Free floating (1979) Pandit etal. (2005) Scirpus lacustris L. Cyperaceae Emergent Kaul and Zutshi 1967 No Sparganium ramosum Huds. Sparganlaceae Emergent Kaul (1986) Kak (1990) Spirodela polyrhiza Schleid. Lemnaceae Free floating Reshi (1984) Kak(1990) Jrapo natans L. Lythraceae Rooted floating Kak(1990) Kak(1990) ryp/)o angustifolia L. Typhaeceae Emergent Kaul (1986) Pandit et al. (2005) VaWsneria spiralisL Hydrocharitaceae Submerged Kak(1990) No Veronica onagollis-aquatica L. Scrophulariaceae Emergent Kaul (1986) No * included in Pandit et al. (2005) as Azolla pinnata 48 Figure 3.6: Surface details of Azolla cristata sporangia with SEM. (A) Megaspore perine surface is variously granular. (B) Massulae with glochidia mainly located on one side of surface. (C) The perine surface is reticulate with filaments. (D) The number of septa in glochidia range from 5-7. Scale bar - 20 [im (B,D); 10 ^m (A); 2 |im (C). 49 Table 3.2: Abundance of macrophytes in Wular Lake during 2008 and 2011 (Actual mean ±SE is given) 2008 2011 Species Mean SE Mean SE Emergents Alisma plantago-aquatica 0.22 0.16 0.28 0.18 Sagittaria sagittifolia 0.17 0.14 0.11 0.11 Phragmites australis 3.72 0.64 4.61 0.72 Polygonum amphibium 0.11 0.11 0.06 0.08 Myriophyllum verticillatum 0.22 0.16 0.17 0.14 Sparganium ramosum 0.17 0.14 0.11 0.11 Bidens cernua 0.17 0,14 0.11 0.11 Lycopuseuropaeus 0.11 0.11 0.06 0.08 Veronica anagallis-aquatica 0.06 0.08 0.00 0.00 Alternanthera philoxeroides 0.72 0.28 4.50 0.71 Typha angustifolia 0.22 0.16 0.28 0.18 Scirpus lacustris 0.22 0.16 0.33 0.19 Echinochloa crus-galli 1.89 0.46 2.39 0.52 Rooted floating Nymphoiodes peltata 7.44 0.91 7.06 0.89 Nymphea alba 0.39 0.21 0.28 0.18 Nelumbo nucifera 1.22 0.37 0.83 0.30 Trapa natans 18.06 1.42 16.17 1.34 Potomogeton natans 1.06 0.34 0.94 0.32 Nymphaea tetragona 0.22 0.16 0.17 0.14 Marsilea quadrifolia 0.28 0.18 0.22 0.16 Submerged Ceratophyllum demersum 3.17 0.59 2.50 0.53 Hydrilla verticillata 1.44 0.40 0.94 0.32 Myriophyllum spicatum 1.94 0.46 1.78 0.44 Potomogeton pusillus 0.56 0,25 0.56 0.25 Potomogeton crispus 0.33 0.19 0.22 0.16 Potomogeton lucens 2.72 0.55 2.50 0.53 Potomogeton pectinatus 0.61 0.26 0.72 0.28 Vallisneria spiralis 0.17 0.14 0.06 0.08 Free floating SaMnia natans 1.17 0.36 0.67 0.27 Spirodela polyrhiza 0.78 0.29 0.67 0.27 Hydrocharis dubia 2.72 0.55 2.94 0.57 Azollo cristata 6.50 0.85 8.28 0.96 Lemna minor 0.50 0.24 0.50 0.24 50 Species 2011 18 - a 16 - 14 - 0 12 1 u 1 10- c c 3 8- b 6 - d h 4 - e e e f ^ f 2 - g g g g g • n - E 3 0! O ro 13 o 3 •D o C c c a Q. s: ra Q. I o •s, O •Q Q- LU I CO Q. W 5 z U ^ Species Figure 3.7: Mean abundance ±SE of 15 most abundant macrophytes in Wular lake in 2008 and 2011. Bars capped by the same letter are not statistically different (p>0.05). Tra nat = Trapa natans, Nym pel = Nymphoides peltata, Azo cri = Azolla cristata, Phr aus = Phragmites australis, Cer dem = Ceratophyllum demersum, Hyd dub = Hydrocharis dubia, Pot luc = Potomogeton leucens, Myr spi = Myriophyllum spicatum, Ech cru = Echinochloa crusgalli, Hyd ver = Hydrilla verticellata, Nel nuc = Nelumbo nucifera, Sal nat = Salvinia natans, Pot nat = Potomogeton natans, Spi pol = Spirodella polyrhiza, Alt phi = Alternanthera philoxeroides. 51 20 •• 2008 g?^ 2011 15 - ai o c m •a 10 3 XI < 5 - 1 /4. philoxeroides W. pe/fafa T. natans A. cristata Species Figure 3.8: Overall mean abundance ±SE of the selected invasive macrophytes in Wular Lake during 2008 and 2011. Bars capped by the same letter are not significantly different. 52 Overall Abundance 1.020 ^ (R^=0.50;p=0.29) 1.015 o > 1.010 1.005 O 1.000 0.995 03 C/5 0.990 0.985 12 3 4 0.400 0.56 1 Emergents Bo ^ (R^=0.23;p=0.52) o 0.395 (R'- =0.07; --0 72) v> 0.54 u > 'r—i > 0.390 0 0.52 Q QC3 O 0.385 O 0.50 C3 0.380 cS 0.48 1 0 S^ in 0 J/2 O 0.375 0.46 0 1 0 1 Free Floating Submerged 0.60 0.77 E, D •+-» 0.58 O' (R^^a87; p=0.05) 0.76 (R^=0.67;p=O17) en 0.56 0) 0.75 > 0.54 5 0.74 O 0.52 0.73 o 0.50 o 0.48 o 0.72 c3 0.71 0.46 •0 1/3 0.44 0.70 0 1 0 12 3 4 5 6 A. philoxeroides Abundance A. philoxeroides Abundance Figure 3.9: Relationship between the Shannon-Wiener Diversity Index (H') and Alternanthera philoxeroides abundance in Wuiar Lake (A) overall abundance of macrophytes (B) Rooted floating macrophytes (C) Emergent macrophytes (D) Free floating macrophytes and (E) submerged macrophytes. 53 The results reveal that variability in water temperature due to season is much higher with little variability between sites and year. All the pair-wise seasonal comparisons of mean temperatures are significantly different (p<0.05). The pair-wise comparisons of water temperature at sites revealed that only five pairs (S3 vs SI, S3 vs S2, S4 vs S3, S6 vs S5 and S5 vs S3) are significantly different (Table 3.4). Depth Water depth showed large spatial and temporal variation during the study period. Among the selected sites, depth ranged from a minimum of 0.2m at S6 during winter to a maximum of 4.4 m at S4 during spring. The overall mean depth of the lake in 2008 was 2.10 m and in 2011 the average depth was 1.97m (Table 3.6). The plot of means reveals that variability in depth due to season is largest followed by site variability (Figure 3.10). All the pair-wise seasonal comparisons are significantly different {p<0.05; Figure 3.10b). Of the different pair-wise site combinations, S6 vs SI, S3 vs S2, S5 vs S2 and S5 vs S3 are not significantly different (p>0.05) while the remaining combinations of sites are significantly different (p<0.05; Figure 3.10c, d). Transparency Water transparency ranged from 0.2-2.4 m in the lake (Table 3.3). The maximum transparency of 2.7 m was recorded at S4 in spring 2008 while the lowest transparency 0.2 m was observed at S6 in winter 2011 (Table 3.6). All the pair-wise seasonal combinations revealed significant differences (p<0.05; Figure 3.11). There was no significant difference in transparency between years (p>0.05). Among the selected sites, significant differences (p<0.05) were observed between 4 pair-wise combinations viz., S4 vs SI, S4 vs S2, S6 vs S3, S5 vs S4 and S6 vs S4 (Table 3.4). All the remaining combinations were non significant (p>0.05) (Table 3.4). pH The pH of water at all the sites ranged from 7.10 to 8.90 indicating that the water is in general alkaline in nature. The maximum value of pH 8.9 was recorded at 54 S3 and S6 in summer 2011 and the minimum was also recorde3~in'^0Tl at S6 in spring (Table 3.3). There was high variability in pH in all the seasons with highest in summer season (Figure 3.11). All the pair-wise seasonal comparisons showed statistically significant differences (p<0.05) except winter and spring (p>0.05). The overall mean seasonal values of pH were 8.09, 7.70, 8.38 and 7.65 in autumn, spring, summer and winter respectively (Table 3.5). There was no significant difference in the mean pH of the sites and between years (p>0.05; Table 3.4 and 3.6). Dissolved Oxygen The concentration of dissolved oxygen ranged from 3.2 mg/L at site S2 in summer 2011 to 11.7 mg/L at site S6 in winter 2008. The overall mean value of dissolved oxygen for Wular lake was 8.07 mg/L in 2008 and was significantly lower in year 2011 (7.67 mg/L; P<0.05; Table 3.6). The average seasonal concentration was 8.12, 7.63, 5.31 and 10.41 mg/L in autumn, spring, summer and winter respectively (Figure 3.11). All the pair-wise seasonal comparisons are significantly different (p<0.05. Table 3.5a). Pair-wise comparison of means of sites revealed that the concentration of dissolved oxygen at all the sites is significantly higher (p<0.05) compared to site S2. Besides, S4 and S6 were also significantly different (p>0.05; Table 3.4). The remaining combinations are non-significant (p>0.05; Table 3.4). Conductivity The conductivity values depicted clear spatial and temporal variations during the present study and were higher in winter and low in summer season. The conductivity ranged from 170 |iSCm"' at site SI to 452 |iSCm"'at site S3 with an overall mean of 278.08 [iSCm\ All the pair-wise seasonal comparisons depicted significant differences (p<0.05; Figure 3.11; Table 3.5). Pair-wise comparison of sites reveals that S3 vs SI, S3 vs S2, S4 vs SI, S6 vs SI, S6 vs S2 and S5 vs S3 are significantly different (p<0.05; Table 3.4). Conductivity was significantly higher in 201 l(p>0.05; Table 3.6). 55 Calcium and magnesium hardness Calcium and Magnesium showed a similar trend of low values in warm seasons and higher values in cold season. The concentration of calcium was much higher than that of magnesium and ranged from 17 mg/L at S2 in summer 2008 to 71 mg/L at S3 in winter 2011. The seasonal mean values of calcium are 43.81 mg/L, 35.31 mg/L, 23.58 mg/L and 59.08 mg/L in autumn, spring, summer and winter respectively. Magnesium concentration ranged from 5.5mg/L at S6 in summer 2008 to 36.5mg/L at S4 in winter 2008. The seasonal mean values of magnesium for 2008 and 2011 are 16.58, 15.69, 8.31 and 27.46 mg/L in autumn, spring, summer and winter respectively (Table 3.5). Calcium revealed statistically significant differences between all pair-wise seasonal combinations (p<0.05) but in case of magnesium all pair-wise seasonal combinations except between autumn and spring (p>0.05) were significant. There was greater variability in magnesium during spring than other seasons (Figure 3.12). There was little variation in the concentration of calcium between the selected sites. In case of magnesium, significant difference was observed in only one pair-wise site combination (S4 vs S6) (Table 3.4). Calcium concentration was significantly higher in 2011 (p<0.05) while as magnesium in 2008 (Table 3.6). Chloride The chloride concentration ranged between 9.0 mg/L at S2 in winter 2008 to 32 mg/L at SI in autumn 2011. The maximum concentration was observed in spring season with a mean value of 26.25 mg/L and minimum seasonal concentration was recorded in winter with a mean value of 12.81 mg/L (Figure 3.12). There is significant effect of both season and site on the chloride concentration (p<0.05). All the pair-wise seasonal comparisons are significantly different (Table 3.5) while as the pair-wise comparison of sites reveals that S2 vs SI, 84 vs S2, S4 vs S3 and S6 vs S4 are significantly different (p<0.05). Spatial variability in chloride concentration 56 (U C (D 0) E E Q. CO E ^ < C3O 52-: 4 - U-: >5-; 3 - I I ?5-S2 - 2 - 1 - ?6-S3 - T" T— CN ro •* in CO lO o in o in w w W W W CO o d d Differences in mean le\«ls of Site Figure 3.10: Spatial and temporal variations in water depth at the selected sites in Wular Lake during 2008 and 2011; (a) plot of means: the longest horizontal line represents overall mean whereas smaller horizontal lines on the vertical bar of season represents mean depths in different seasons (b) box plot of seasonal means and (c) of sites, (d) Tukeys HSD plot of site means (95% confidence level). Box length is the interquartile range, whiskers give 95% confidence limits and open circles denote extreme values. 57 o 2.5 H t 2.0 1 1.5 o 1.0 1 1 1 0.5 i 1 1 1 1 1 1 1 r to w c^ c3 (S (8 ^ I CO 1 1 1 1 1 8.5 - 1 8.5 t 1 1 f 1 1 1 t 8.0 1 t 8.0 - ^ 1 - 1 , 1 1 1 a 1 7.5 I 7.5 - I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 g w S^ c3 ^ c8 c8 I 8 450 400 F o 3b0 c/) 3 300 O LU 250 200 Figure 3.11: The box-plot of mean seasonal and mean site variation of different water parameters at the selected sites in Wular lake during 2008 and 20 U. The dark line in the box is median value whereas the length of the box shows the variability; longer the box, more the variability. 58 o 35 I _ 30 ^ I 25 o 20 S> 15 10 5 1 1 1 1 D) C £ •c 3 Q. I 3 CO 3 < CO 0) 1_ 0) 0) 0) (1) •c c E 4-^ 3 Q. E a c CO E CO E ^ < ^ C3O o 30 1 250 I 0 1 25 - p^ 1 D5 200 E, 1 E. I 1 1 M T3 20 1 1 ^ 150 1 c •c 1 15 —1 1 ^ 100 1 < O 1 10 - 50 - 1 1 1 1 D) c C a> c 0) E E E E 3 Q. •«—3 > a I CO E CO E 3 3 3 3 < CO < CO Figure 3.12; The box-plot of mean seasonal variation of different water parameters at the selected sites in Wular lake during 2008 and 2011. The dark line in the box is median values whereas the length of the box shows the variability; longer the box, more the variability. 59 Table 3.3: Range, mean and SD of different water quality parameters in Wular lake during 2008 and 2011 Parameter SI S2 S3 S4 S5 S6 Air Temp. Range 3.4-32.6 3.3-32.8 3.6-32.3 3.4-31.7 3.4-32.9 3.7-33.7 °C Mean 18.61 18.37 18.73 18.07 17.63 18.15 SD(±) 10.04 10.20 10.17 9.78 10.10 10.29 Water Temp. Range 2.7-29.5 2.8-28.5 2.8-29.5 2.6-28.9 2.5-28.9 2.8-29.4 °C Mean 15.32 15.20 15.75 15.18 15.14 15.49 SD(±) 9.12 8.93 9.33 9.25 9.17 9.03 Depth Range 0.3-2.9 0.9-3.3 0.7-3.3 0.9-4.4 0.5-3.7 0.2-2.7 (m) Mean 1.54 2.11 2.17 2.63 2.20 1.57 SD(±) 0.82 0.65 0.80 0.92 1.02 0.78 Transparency Range 0.3-2 0.7-1.5 0.4-2.4 0.5-2.4 0.4-2.2 0.2-1.7 (m) Mean 1.06 1.11 1.26 1.42 1.16 0.99 SD(±) 0.50 0.25 0.66 0.51 0.53 0.46 pH Range 7.30-8.60 7.42-8.50 7.30-8.90 7.30-8.84 7.54-8.40 7.10-8.90 Mean 7.93 7.87 7.99 8.03 7.96 7.97 SD(±) 0.43 0.32 0.48 0.48 0.27 0.55 DO Range 4.4-10.4 3.2-10.8 4.3-11.5 5.2-11.2 4.8-11.6 5.2-11.7 (mg/L) Mean 7.95 6.96 7,91 7.88 8.03 8.48 SD(±) 1.72 2.36 2.11 1.85 2.02 1.84 Conductivity Range 170-384 194-390 210-452 187-406 209-384 196-382 HS/Cm Mean 261.75 269.29 292.92 283.00 274.54 287.00 SD(±) 68.50 66.51 67.58 59.03 53.81 59.59 Calcium Range 19-68 17-63 21-71 20-68 17-69 19-65 (mg/L) Mean 39.04 40.58 42.13 40.63 40.92 39.38 SD(±) 13.60 14.68 15.04 13.88 14.69 13.58 Magnesium Range 5.7-31.7 6.4-34.4 7-32.5 6.8-36.5 6.4-27.4 5.5-31 (mg/l.) Mean 16.48 17.31 16.99 18.54 17.25 15.50 SD(±) 7.47 7.85 8.13 8.24 6.66 7.17 Chloride Range 11.0-32 9.0-28 11.0-26 10.0-31 11.0-28 11.0-30 (Hg/L) Mean 20.04 17.21 18.21 21.79 19.54 19.21 SD(±) 5.83 5.99 4.61 6.82 5.99 6.23 Alkalinity Range 49-238 36-220 54-261 52-261 39-210 44-186 (mg/L) Mean 129.13 115.17 133.50 139.67 117.88 104.04 SD(±) 63.42 58.77 69.07 68.18 57.11 47.92 Sodium Range 4.5-8.7 4.5-9.3 4.3-8.1 4.5-9.3 3.4-8.3 4.2-9.7 (mg/L) Mean 6.30 6.22 5.97 6.48 5.80 6.16 SD(±) 1.06 1.38 1.27 1.46 1.14 1.59 Potassium Range 2.2-4.4 1.8-4.5 1.9-4.3 2.1-4.7 2.5-4.4 2.1-4.3 (mg/L) Mean 3.24 3.19 3.15 3.38 3.29 3.43 SD(±) 0.53 0.68 0.78 0.77 0.56 0.63 Ammonical N Range 76-287 75-248 51-306 78-377 83-393 67-275 (Ug/L) Mean 149.71 130.33 147.42 163.88 168.50 143.29 SD(±) 64.43 38.72 74.25 73.55 83.40 55.34 Nitrate N Range 247-524 119-512 174-448 259-497 165-436 193-487 (Hg/L) Mean 353.00 335.75 332.33 363.13 330.75 356.21 SD(±) 72.02 89.04 63.04 75.27 82.57 75.81 OPP Range 31-122 32-108 21-92 31-103 27-113 24-128 (Hg/L| Mean 68.96 61.29 54.67 63.25 65.67 68.00 SD(±) 25.15 20.62 19.96 22.04 24.64 29.04 Total P Range 143-263 129-248 131-271 138-291 129-283 138-319 (Ug/L) Mean 195.21 186.13 190.50 208.42 200.88 213.83 SD(±) 36.99 38.75 39.36 50.62 44.45 49.93 60 ID rH m o LO 00 OI rH ID cn LO o OI rH ro LO ID o LO 1^ OI ro 00 ro 00 rH ro 00 O OI 01 LO rH LO LO OI 00 LD ID ID ID ID fri LD LD rH rH 00 LD Osl o O ro ro rH OI O LO O ro rH 00 ro O o 01 rH LD o ro x: ro LO ro o ID LO LO a LO Lfi LD LO 00 LO in ro ro ro rri Ol ro ro ro ro ro rH ro ro rvi o ro ro rH ro ro J: o. ro 00 o LD 00 LD 00 00 rH ro ro ro 00 LO <* LO 00 Lfi LO LO LD o. 01 O ro 00 ro ni oi K ro ID m ro IX) rH ID d rH LO rH LO ^ rH rH rH rH rH rH rH OI r-t rH o. 00 o OI LO 00 OI ro LD ro o Ol ro LO Ol c <* rH rH rH 00 OJ o rri OI LD rH ro O II ro OI ro Ol ro o ro O Q. -a ro ro ro ro rri d ri c O rM 00 o LD OI o r\j LD 00 fO a rH OI O 1^ ro rsi 00 rM 00 LO Ol ro ro LO 00 LO LO o o ID LD LO LD LO LO o rH Ol (N ro O 1^ 00 o ro ro rH LD 00 O 01 00 LO LO 1^ LD' LD LD r-. oJ O 00 13 oi ro 01 d LO rH ro ro O LO -a rsi oi rH rH (N 00 rH o rH >-. rH rH rH rH rH LO Ol LD OJ r-l -O 00 rH rH rH LO LO ro rH & 01 o OJ rM Ol 00 o rsj LO OI LO LO 00 00 00 o LD Ol Ol 00 rH oi oi OI LO o o 00 01 d rH rH OI rH rH rsi rH rH r-i r-i o 00 01 LO O 00 Ol LD 00 rH ro rn 01 LO LO 00 LD LO ro o 00 LH ro "a; bO LD 00 LO ro LO Lfi rH >-. rH rH rH rH rH rH r-i a rH 00 Ol r-i rH rH 00 ro ro O) 00 C/1 00 00 LO 00 LO o rH LD OI o i-, ro ro Oj LD LD ro (U o LO OI o o OI •t-j ro LO ro 01 oi o LO oi V ro ro rri (U ro OJ -*—• ro <* LD LD rM LD OI LO rH Ol 1^ Ol Ol O (N rH 01 rH T3 m LD o LO rH rH rH rH rH rH O O O LO «3- OI Ol ro Ol LO OI o rH rH LO t 13 Ol (/I rH rH > (U LO LO LO LO «d- LO 00 O Lfi LO o rH rH Ol ro o rH l-N & c3 > ro ro (U LO LD LO (U 00 LD ro o on LD O 01 00 LO 00 LO rv Ol >^ 00 00 00 00 00 LD O rH ro i< rH Ol ro ^ o u IT) c <^* E E a 3 c 00 "Z _ E .= -^ Q rH J«: Q •HiNrn^uiiODc/i 3 o a a 3 > 3 00 o O 3 to h- -I (M fM H -J was greater than seasonal. Mean chloride concentration was significantly higher in 2011 (Table 3.6; p<0. 05). Alkalinity The alkalinity ranged from 36 mg/L at site S2 in summer 2008 to 261 mg/L at site S4 in winter 2011. The total mean value of alkalinity in Wular lake during the study period was 123.22 mg/L and the seasonal means were 120.81, 52.75, 106.94 and 212.42 mg/L for spring, summer, autumn and winter, respectively (Figure 3.12). The mean value of alkalinity in winter was much above average and below average in other seasons. All the pair-wise comparisons of the seasonal means depicted significant differences (p<0.05; Table 3.5). Year 2011 had a significantly higher alkalinity than year 2008 (p<0.05; Table 3.6). Sodium and Potassium The sodium concentration ranged from 3.4mg/L at site S5 to 9.7mg/L at site S6. The mean seasonal concentration was 8.02, 5.76, 5.34 and 5.5 mg/L for spring, summer, autumn and winter respectively (Figure 3.12). The mean value of sodium concentration in 2011 was significantly higher than in 2008 (p < 0.05; Table 3.6). The potassium concentration was lower than sodium and ranged from 1.8 mg/L at S2 to 4.5 mg/L at the same site with higher values in spring and winter and lower values in summer and autumn. Potassium concentration was higher in 2008 than in 2011. Ammonical Nitrogen The spatial and temporal variations in the concentration of ammonical nitrogen during the study period are given in (Figure 3.13a, b). The concentration of ammonical nitrogen ranged from 52 mg/L at S3 during summer 2011 to 393 mg/L at S5 in winter 2011 (Table 3.3). The overall mean of ammonical nitrogen in Wular Lake during 2008-2011 was 150.52 mg/L with non-significant difference between the years (p>0.05; Table 3.6). The box plot reveals that there is greater variability in ammonical nitrogen concentration in winter season as compared to other seasons (Figure 3.13b). During winter, the ammonical nitrogen concentration was above average and in other seasons 62 below mean level. There was a significant difference in concentration of ammonical nitrogen in different seasons except between spring and autumn, as is evident from pair-wise seasonal comparisons (p<0.05; Table 3.5). Among the sites only two pairs were significantly different (S4 vs S2 and S5 vs S2). The remaining combinations were non-significant (Table 3.4). Nitrate Nitrogen The overall mean nitrate nitrogen concentration was much higher than ammonical nitrogen. The nitrate concentration ranged from 119 jig/L at S3 in summer 2008 to 524 \iglh at SI in winter 2011, with a total mean value of 345.19 ^g/L during the study period. The mean value of nitrate nitrogen concentration in 2008 (325.3 )ig/L) was significantly lower (p<0.05) than the concentration in 2011 (365.1 |a,g/L) (Table 3.6). The plot of means reveals that the nitrate concentration was below average in summer and above average in other seasons (Figure 3.13c, d). The temporal (year- wise) variability was more pronounced than spatial (between sites). Tukey multiple comparisons of seasonal means revealed statistically significant difference between summer vs autumn, summer vs spring and winter vs summer concentrations (Table 3.5). Among sites, 4 pair-wise combinations (S4 vs S2, S5 vs S4, S4 vs S3 and S6 vs S3) were significantly different (Table 3.4). Orthophosphate phosphorous The concentration of ortho-phosphate phosphorous ranged from 21 [ig/L at site S3 to 128 )a,g/L at site S6 (Table 3.3). The overall mean concentration for the study period was 63.64 ^ig/L, with much higher concentration in spring season and low concentration in summer and autumn seasons (Fig. 3.14a, b). The mean seasonal concentration were 97.78, 39.22, 52.25 and 65.31 ng/L for spring, summer, autumn and winter, respectively (Table 3.5). The box-plot of the seasonal mean revealed that there was greater variability in concentration of ortho-phosphate phosphorous during spring and least in winter (Figure 3.14b). All the pair-wise comparisons of mean seasonal concentrations were significantly different (p<0.05; Table 3.5). The comparison of pair-wise site 63 combinations revealed that significant differences between 5 pairs (S3 vs SI, S3 vs S2, S4 vs S3, S5 vs S3 and S6 vs S3) (p<0.05). Total Phosphorous Total phosphorous concentration was three fold higher higher than ortho- phosphate phosphorous. It ranged from 129 |a,g/L at site S2 and S5 in summer 2011 and autumn 2011 respectively to 319 ng/L at S6 in spring 2011, with an average value of 199.16 |ig/L during the study period. The mean seasonal values were 257.39, 172.81, 169.83 and 196.61 }xg/L for spring, summer, autumn and winter respectively (Table 3.5). All the pair-wise comparisons of mean seasonal concentrations were significantly different (p<0.05; Table 3.5), with much higher concentration in spring. The mean concentration of total phosphorous was significantly higher in 2008 (p<0.05; Table 3.6). There was greater seasonal variability in concentration of total phosphorous than ortho-phosphate phosphorous (Figure 3.14c, d). Principal Component Analysis (water parameters) The result of the principal component analysis (PCA) of the water quality data on 17 parameters for six selected sites is presented in (Table 3.7). The scree plot reveals that the slope changes from steep to shallow after the first three factors. The eigen value also drops to less than 1 when we move from factor 3 to factor 4, hence overall three components were extracted for analysis (Table 3.7). The three components account for 80.36% of the total variance of the original data indicating that larger part of the variation was accounted for by the extracted components. The components were further rotated using varimax technique to maximize high correlations and minimize lower ones (Table 3.7). 54 WinterT 400 - 350 - 200 300 - d 250 - E 150 - itumn E 200 - pring S2^ 150 - 100 - 100 dimmer 50 -. -ar (7? >- m c c E E CO Q. "3 CO E < CO E 300 i 200 - c a) -*—• E 'L_ E c -*—Z3< CO E < CO Figure 3.13: Plot of means and box plot of seasonal means of ammonical nitrogen (a, b) and nitrate nitrogen (c, d) at the selected sites in Wular Lake during 2008 and 2011. The longest horizontal line in figure 'a' and 'c' represents overall mean whereas, the horizontal lines on the vertical bars represents mean concentration. Box length is the interquartile range, whiskers give 95% confidence limits and open circles denote extreme values. 65 100 Springr 90 5~ 80 3 70 2Q11iWinter S 60 2008 S3 50 Autumn 40 •dimmer. TO (D o "3" >- ro CO C (U 0) E E CO Q. CO £ < CO 300 - 250 - o> ^ 200 - 150 C7) c 0 0) E £ c Q. CO £ < 3 CO Figure 3.14: Plot of means and box plot of seasonal means of orthophosphate phosphorous (a, b) and total phosphorous (c, d) at the selected sites in Wular Lake during 2008 and 2011. The longest horizontal line in figure 'a' and 'c' represents overall mean whereas, the horizontal lines on the vertical bars represents mean concentration. Box length is the interquartile range, whiskers give 95% confidence limits and open circles denote extreme values. 66 Table 3.7: Principal components and Varimax rotated components of 17 water quality parameters studied. Eigen values explained Principal components Rotated components 1 2 3 1 2 3 9.142 3.513 5.921 8.394 3.658 1.61 Percent of total variance explained 1 2 3 1 2 3 53.775 20.667 5.921 49.374 21.516 9.437 Component loadings 1 2 3 1 2 3 Air temperature -0.964 0.119 -0.16 -0.977 -0.033 0.115 Water Temperature -0.969 0.078 -0.137 -0.97 -0.075 0.135 Depth -0.61 0.601 0.147 -0.626 0.488 0.354 Transparency -0.373 0.68 0.419 -0.337 0.594 0.558 Calcium 0.887 -0.238 0.175 0.925 -0.097 -0.09 Magnesium 0.903 -0.108 0.028 0.881 0.039 -0.225 Sodium -0.093 0.836 -0.113 -0.242 0.814 -0.015 Pottassium 0.703 0.44 -0.186 0.552 0.555 -0.331 Conductivity 0.933 0.023 -0.096 0.856 0.178 -0.34 PH -0.645 -0.384 0.152 -0.515 -0.489 0.288 Ammonical N 0.834 -0.181 -0.013 0.815 -0.043 -0.252 Nitrate nitrogen 0.604 0.268 0.544 0.686 0.341 0.382 Orthophosphate Phosphorous 0.423 0.823 0.028 0.29 0.879 -0.019 Total Phosphorous 0.234 0.829 -0.068 0.083 0.858 -0.06 Chloride -0.631 -0.282 0.576 -0.398 -0.403 0.699 Alkalinity 0.94 -0.031 0.007 0.899 0.121 -0.248 Dissolved oxygen 0.891 -0.094 0.144 0.902 0.047 -0.109 67 The component 1, which explains 49.37% of the total variation, has strong loadings on 8 factors including air temperature, water temperature. Calcium, magnesium, dissolved oxygen, alkalinity, conductivity, ammonia nitrogen and moderate loadings on depth, potassium, pH and nitrate nitrogen. The second component, which explains 21.51% of the total variation, has strong loadings on three factors including sodium, orthophosphate phosphorous and total phosphorous. The third component which explains 9.43%) of the total variation represents chloride. 3.3.3 Sediment Characteristics Sediment Composition The granulometric composition of the sediments in the Wular lake are presented in Table 3.8. Textural analysis revealed that most of the sediments are fine to medium textured clay-silt sediments with the total percentage of clay-silt fraction ranging up to 80%). Only at one site (S5), the percentage of sand was high (42.4%o). In samples collected at S2, which lies far away from drainage inlet, consistent predominance of clay and silt particles was recorded. The sediments in general can be classified as 'silt-loam'. Table 3.8: Granulometric composition of lake sediments Sand (%) Silt (%) Clay (%) SI 21.40 42.30 36.30 S2 19.30 39.20 41.50 S3 22.70 41.80 35.50 S4 39.30 33.00 27.70 S5 42.40 38.40 19.20 S6 26.90 44.20 28.90 pH The sediments in general were alkaline at all the sites (Table 3.10). The pH values fluctuated between a minimum of 7.05 at site S5 in summer 2008 to a maximum of 8.54 at site S3 in spring 2008 (Table 3.9). The mean pH values during the study period ranged from 7.30 ±0.16 at S2 to 7.91±0.31 at S3. The pair-wise comparison of sites revealed that S2-S1, S4-S1, S5-S1, S3-S2, S4-S3, S5-S2 and S6- S5 are significantly different (p<0.05; Figure 3.16). Among the seasons, pH was low in summer season and high in winter season, but the difference was not significant 68 (p>0.05; Figure 3.15). The correlation matrix did not reveal any significant correlation of pH with any other parameter. Calcium (%) The calcium levels in Wular lake sediments ranged between a minimum of 1.74 % at S5 in autumn 2011 to a maximum of 4.95 % at S3 in winter 2008. The mean calcium values during the study period ranged from 2.75 ±0.58 at S6 to 3.59±0.79 at S3. There were significant differences in the mean value of calcium among all the pair-wise seasonal combinations (p<0.05). There were significant differences among sites (P<0.05) except four site-pairs viz., S2-S1, S5-S2, S6-S2 and S6-S5 (P>0.05; Table 3.10). Summer season recorded the lowest calcium level (2.37 %) while winter measured highest (3.82 %; Table 3.11). There was no significant difference in calcium between 2008 and 2011. Utilizing the combined data from all the sites, calcium showed a weak correlation with potassium. Magnesium (%) Magnesium levels fluctuated from 0.33% at SI in summer 2011 to a maximum of 0.97% at S4 in spring 2008. The mean magnesium values at the selected sites ranged from 0.58 ±0.14% at SI to 0.67±0.09%) at S6 during the study period (Table 3.9). Magnesium recorded lower values in summer and higher in spring season (Figure 3.15). There was no significant difference in magnesium levels among sites (p>0.05). On seasonal basis there were significant differences between spring and autumn, summer and spring, and winter and spring (p<0.05, Table 3.11). Magnesium levels are much lower than calcium and the ratio between calcium and magnesium varied from 4.07-5.68 at different sites. Potassium (%) The potassium values ranged from 0.32% at S4 to 1.13% at SI. The mean potassium values at the sites ranged from 0.56 ±0.17%) at S5 to 0.76±0.17%) at S3 during the study period. On seasonal basis, lowest mean value was recorded in autumn season (0.51 %) while highest mean value was recorded in winter (0.79 %; Figure 3.15). The pair-wise seasonal comparisons revealed that there was no significant difference between winter and spring seasons (p>0.05) while other seasons showed significant differences (p<0.05, Table 3.11). The pair-wise site comparisons 69 revealed that S5-S3, S4-S3, S5-S1, S2-Sland S3-S2 had significant differences (p<0.05; Table 3.10). Sodium (%) The sodium concentrations ranged between 0.07% at site S2, S4 and S5 to 0.18% at site S6 during the study period. There was little and non-significant (p>0.05) variation in the mean values between sites and fluctuated from 0.11 ±0.03% at S5 to 0.13±0.03% at S3. On seasonal basis, spring and summer, and winter and summer values differed significantly (p<0.05; Table 3.11). Organic Carbon (%) Sediment organic carbon shows considerable spatial and temporal variations. It ranged from a minimum of 6.34% at S3 in autumn 2008 to a maximum of 14.1% at S5 in winter 2008 (Table 3.9). On seasonal basis the average values were 9.04%, 9.71%, 8.67% and 10.49 % for autumn, spring, summer and winter seasons, respectively (Table 3.11). The pair-wise comparison revealed no significant difference between summer and autumn seasons (p>0.05), remaining seasonal comparisons were significantly different (p<0.05, Table 3.11). Most of the pair-wise site comparisons revealed significant differences (p<0.05; Table 3.10). Nitrogen (%) Nitrogen concentration fluctuated from a minimum of 0.32% to a maximum of 1.48% during the present study. The lowest concentration was recorded at Site S6 while the highest concentration was observed at site S5 (Table 3.9). The mean values ranged from 0.55±0.15% to 0.79±0.29%. Between the two years, the overall mean concentration of nitrogen was significantly higher in 2011 than 2008 (Table 3.12). The pair-wise seasonal comparisons revealed significant difference between spring and autumn, winter and autumn and summer and spring (p<0.05). The highest concentration was observed in spring season and lowest concentration in summer season (Figure 3.15). Among the pair-wise site comparisons, S4-S2, S5-S3, S5-S4 and S6-S5 were significantly different (p<0.05; Table 3.10). 70 Phosphorous (%) Phosphorous ranged from 0.03% at S6 to 0.14% at S2. The mean values of phosphorous ranged from a minimum of 0.05 ± O.Olat S5 and S6 to 0.08% ± 0.02 at S2. Pair-wise comparisons revealed significant difference only between spring and summer (p<0.05). There was no significant difference between any other pair-wise seasonal combinations (p>0.05). C/N Ratio C/N ratio ranged between 5.84 at SI to 35.94 at S6. The mean values fluctuated between 13.65± 4.15 to 19.74 ± 6.39 during the study period. The pair-wise site comparison revealed significant differences between sites SI and S6 (p<0.05) while the remaining sites did not differ significantly. On the seasonal basis, C/N ratio was significantly lower in spring compared with other seasons (Table 3.11; Figure 3.15). Principal Component Analysis (Sediment) The result of the principal component analysis (PCA) of the sediment characteristics is presented in Table 3.13. The three components account for 62.30 % of the total variance of the original data. The principal component 1, which explains 25.09% of the total variation, represents a combination of five factors including potassium, calcium, Phosphorous, pH and sodium. The second component, which explains 20.99%) of the total variation, represents C/N ratio and nitrogen. The third component which explains 16.21% of the total variation represents organic carbon (Table 3.13). 3.3.4 Mineral Nutrients in Plants Mineral analysis carried out for the four selected plant species is given in Table 3.14. The mineral nutrients viz. calcium, magnesium, nitrogen, phosphorous and potassium showed variations in regard to the plant species analyzed. 71 Table 3.9: Range, mean and SD of sediment characteristics in Wular lake during 2008 and 2011 Parameter SI 52 S3 S4 S5 S6 PH Range 7.06-8.35 7.09-7.57 7.4-8.54 7.25-7.9 7.05-8.01 7.32-8.01 Mean 7.78 7.30 7.91 7.52 7.39 7.66 SD(±) 0.39 0.16 0.31 0.19 0.23 0.21 Ca (mg/L) Range 2.23-4.24 2.15-3.78 3.54-4.95 2.15-4.36 1.74-4.25 1.85-3.86 Mean 3.06 2.90 3.59 3.26 2.84 2.75 SD(±) 0.54 0.51 0.79 0.71 0.85 0.58 Mg (mg/L) Range 0.33-0.82 0.39-0.96 0.43-0.93 0.43-0.97 0.39-0.93 0.52-0.84 Mean 0.58 0.60 0.62 0.61 0.65 0.67 SD(±) 0.14 0.12 0.14 0.14 0.16 0.09 K (mg/L) Range 0.37-1.13 0.38-0.85 0.47-1.05 0.32-0.96 0.32-0.84 0.32-0.99 Mean 0.75 0.62 0.76 0.62 0.56 0.65 SD(±) 0.20 0.13 0.17 0.20 0.17 0.14 Na (mg/L) Range 0.08-0.16 0.07-0.16 0.08-0.17 0.07-0.16 0.07-0.17 0.08-0.18 Mean 0.12 0.12 0.13 0.12 0.11 0.12 SD(±) 0.03 0.02 0.03 0.03 0.03 0.03 *SOC Range 6.4-11.6 7.6-12.5 6.34-10.4 7.4-11.4 8.8-14.1 8.2-12.3 Mean 8.63 9.35 8.45 9.13 11.31 9.99 SD(±) 1.16 1.09 1.14 0.87 1.58 1.15 N (Hg/L) Range 0.37-1.25 0.34-0.79 0.39-0.98 0.35-1.17 0.38-1.48 0.32-0.93 Mean 0.69 0.56 0.58 0.58 0.79 0.55 SD(±) 0.23 0.15 0.17 0.19 0.29 0.15 5.84- 10.6- 8.57- 7.69- 11.59- C/N ratio Range 21.08 24.71 23.81 24.57 9.0-31.32 35.94 Mean 13.65 17.67 15.47 17.04 15.96 19.74 SD(±) 4.15 4.26 4.10 4.09 5.98 6.39 P Mi) Range 0.13-0.05 0.14-0.04 0.11-0.04 0.10-0.04 0.08-0.04 0.09-0.03 Mean 0.07 0.08 0.07 0.06 0.05 0.05 SD(±) 0.02 0.02 0.02 0.01 0.01 0.01 *SOC=sediment organic carbon 72 Table 3.10: Site wise overall mean of the sediment characteristics in Wular lake during 2008 and 2011 C/N Site PH Ca Mg Na K soc* N ratio P SI 7.78 3.06 0.58 0.12 0.75 8.63 0.69 13.65 0.07 S2 7.30 2.90 0.60 0.12 0.62 9.35 0.56 17.67 0.08 S3 7.91 3.59 0.62 0.13 0.76 8.45 0.58 15.47 0.07 S4 7.52 3.26 0.61 0.12 0.62 9.13 0.58 17.04 0.06 S5 7.39 2.84 0.65 0.11 0.56 11.31 0.79 15.96 0.05 S6 7.66 2.75 0.67 0.12 0.65 9.99 0.55 19.74 0.06 Tukeys LSD 0.218 0.237 0.091 0.021 0.095 0.810 0.155 4.070 0.013 Table 3.11: Seasonal mean of the sediment characteristics in Wular lake during 2008 and 2011 C/N Season pH Ca IVIg Na K SOC N ratio P Autumn 7.55 2.66 0.59 0.12 0.51 9.04 0.51 18.79 0.06 Spring 7.69 3.42 0.73 0.13 0.75 9.71 0.77 13.50 0.07 Summer 7.52 2.37 0.56 0.10 0.60 8.67 0.56 16.91 0.06 Winter 7.62 3.82 0.62 0.14 0.79 10.49 0.66 17.15 0.07 Tul Table 3.12: Yearly mean of the sediment characteristics in Wular lake during 2008 and 2011 C/N Year pH Ca Mg Na K SOC N ratio P 2008 7.62 3.13 0.65 0.12 0.69 9.53 0.60 17.31 0.07 2011 7.57 3.01 0.59 0.12 0.63 9.42 0.65 15.87 0.06 Tui 73 5.0 1 1 4,5 1 1 4.0 X E 3.5 1 Q. (D 3.0 O 2.5 ' '-—1—' 2.0 1 1 1 1 3 a. 3 < CO t 1 1 1 1 1.0 1 o 1 1 1 E E 0.8 1 1 to 0 1 1 c 1 1 1 O) I 0.6 TO 1 M CL 1 1 1 1 0.4 o 1 1 1 1 c o o o 'c ro o 0.14 0 35 o g 0.12 - 30 o g I ' 25 I 0.10 J—. 1 _! I I ; 1 .2 I I 1 1 p__j 20 I 0.08 1 1 15 ' ^~~~ I I I I 0.06 1 —•— I 1 I I Q. 1 1 ^ 1 1 10 0.04 1 1 1 1 1 3 a 3 3 a 3 < CO < CO CO Figure 3.15: Box plots of seasonal variations in the sediment characteristics of Wular lake during 2008 and 2011 (Au=autumn, Sp=spring, Su=summer and Wi=winter). The dark line in the box is median values whereas the length of the box shows the variability; longer the box, more the variability. 74 X E Q. TO o 1- CM CO Tf in CD T- CM CO Tj- in CO CO CO W CO W W CO CO CO CO CO CO 1.0 - e r^ T ^ ^1 E —^ ~<- < 2 £ 0,8 m w c I 0,6 Q. 1 1 1—1— 1 1 1 0.4 1 1 l_ _1_ —L. 1 1 1 1 1 1- c\j CO •* in CD 1- CM CO -"^ in CD CO CO CO CO CO CO CO CO CO CO CO CO 14 I I c o 12 - TO O o 10 'c ro ? 8 - O 1 I 1- CM CO rf in (D T- CM CO •^ in CD CO CO CO CO CO CO CO CO CO CO CO CO TO o •<- CM CO Tj- in CD T- CM CO Tf in CD CO CO CO CO CO CO CO CO CO CO CO CO Figure 3.16: Box plots of variations in tlie sediment characteristics at the selected sites in Wular lake during 2008 and 2011 (Au=autumn, Sp=spring, Su=summer and Wi=winter). The dark line in the box is median values whereas the length of the box shows the variability; longer the box, more the variability. 75 Table 3.13: Principal components and varimax rotated components of the different parameters of sediment analyzed in the present study Eigen values explained Principal components Rotated components 1 2 3 1 2 3 2.72 1.62 1.27 2.259 1.89 1.46 Percent of total variance explained 1 2 3 1 2 3 30.218 17.995 14.09 25.098 20.997 16.21 Component loadings PH 0.394 0.518 -0.252 0.635 0.002 -0.290 Calcium 0.807 0.221 0.155 0.759 0.235 0.305 Magnesium 0.509 -0.079 0.380 0.338 0.156 0.520 Sodium 0.558 0.062 0.182 0.466 0.186 0.311 Potassium 0.686 0.404 -0.016 0.784 0.127 0.050 Sediment organic Carbon 0.145 -0.403 0.786 -0.148 -0.032 0.882 Nitrogen 0.620 -0.723 -0.148 0.004 0.904 0.334 Phosphorous 0.348 0.432 0.059 0.545 -0.119 0.000 CN Ratio -0.588 0.508 0.600 -0.117 -0.963 0.151 76 Table 3.14: Mean seasonal values of tissue concentration (%) of mineral nutrients in the selected species. Season N.peltata A.cristata T. natans A. philoxeroides Calcium Spring 0.70 0.29 0.56 Summer 1.34 0.71 1.22 Autumn 0.76 1.29 0.68 Mean 0.93 0.76 0.82 Magnesium Spring 0.22 0.36 0.20 Summer 0.39 0.68 0.39 0.40 Autumn 0.32 0.87 0.51 0.53 Mean 0.31 0.64 0.37 0.38 Nitrogen Spring 0.80 1.02 1.19 0.66 Summer 1.65 2.06 2.43 1.04 Autumn 1.19 2.97 1.72 1.31 Mean 1.21 2.02 1.78 1.00 Phosphorous Spring 0.12 0.18 0.16 0.14 Summer 0.21 0.21 0.25 0.24 Autumn 0.16 0.26 0.22 0.33 Mean 0.16 0.22 0.21 0.24 Potassium Spring 0.59 0.48 0.57 0.61 Summer 1.07 0.93 1.39 0.98 Autumn 0.78 1.23 1.21 1.17 Mean 0.81 0.88 1.05 0.92 • N.peltata A.cristata IT. natans • A. philoxeroides 3.50 S? 3.00 2.50 ^c 2.00 u c o u tu 3 T .JL.M.... Calcium Magnesium Nitrogen Phosphorous Potassium Mineral nutrient Figure 3.17: Mean (±SD) values of different nutrients in the selected species 77 Calcium concentration ranged from 0.29-1.39% among the selected species. The lowest calcium was recorded in A. cristata in spring and highest concentration in A. philoxeroides in summer. The highest mean values of calcium among the selected species was observed in A. philoxeroides (1.18%) followed by N. peltata (0.93%), T. natans (0.82%)) and A. cristata (0.76%)). Magnesium concentration ranged from 0.20- 0.87%o in the selected macrophytes. The maximum concentration was observed in A. cristata in autumn while as minimum concentration was observed in T. natans in spring. Nitrogen concentration ranged from 0.80-2.97 % in the selected species during the study period. Lowest concentration was observed in A^. peltata while as highest concentration was observed in Azolla cristata in autumn. The mean nitrogen value was highest inA. cristata (2.02%)) followed by T. natans (1.78%o), A'^ peltata (1.21%) and lowest was in A. philoxeroides (1.0%). Phosphorous concentration ranged from 0.12-0.33 %) in the selected species. The maximum concentration was observed in A. philoxeroides while as the minimum concentration was observed in N. peltata (Table 3.14). The potassium concentration ranged from 0.48-1.23%) in the selected species. The mean concentration of potassium was maximum in T. natans (1.05%) followed by A. philoxeroides (0.92%), A. cristata (0.88%) and A^. peltata (0.81%). 3.3.5 Results of Canonical Correspondence Analysis Results of CCA in spring 2008 (Figure 3.18), revealed that the selected invasive species were not governed by any environmental variable. In year 2011, /i. philoxeroides was governed by potassium and nitrate nitrogen whereas pH and calcium governed distribution of JV. peltata. Trapa natans was governed by ammonical nitrogen. The association of A. philoxeroides with Sparganium ramosum and Sagitaria sagitifolia in spring 2008 broke up in spring 2011. A^. peltata had association with the submerged species especially Myriophyllum spicatum and Cratophyllum demersum in both years. In summer 2008 (Figure 3.19) the distribution of A. philoxeroides was governed by total phosphorous but in summer 2011 calcium and conductivity played some role in distribution of Alternanthera philoxeroides. It was mostly associated 78 with emergent species Sparganium ramosum, Echinochloa crusgalli, Sagittaria sagitifolia and Scirpus lacustris in summer 2008, while in summer 2011, A. philoxeroides was associated with Sahinia natans and Lemna minor. For Azolla cristata total phosphorous is the most significant factor governing its distribution in the lake. Trapa natans was not governed by any environmental variable while Nymphoides peltata was governed by transparency in 2008 while in summer 2011, pH and sodium partially governed its distribution in the lake. In autumn 2008 the distribution pattern of Alternanthera philoxeroides was largely governed by water depth but in autumn 2011, calcium, water depth, magnesium and ammonical nitrogen played a role in its distribution (Figure 3.20). The association of Alternanthera philoxeroides with the Sparganium ramosum, Echinochloa crusgalli, Sagittaria sagitifolia and Scirpus lacustris in autumn 2008 was maintained in autumn 2011 as well. Distribution of Azolla cristata was not governed by any environmental variable in both the years. Trapa natans had weak correlation with magnesium in 2008 and alkalinity and nitrate nitrogen in 2011. Nymphoides peltata distribution was governed by alkalinity in autumn 2008 while in autumn 2011 it was weakly governed by transparency and sodium. Nymphoides peltata was associated mostly with submerged macrophytes and this association was maintained in autumn season of both the years (Figure 3.20). Figure 3.21 shows the CCA plot of the pooled data of all the seasons for the years 2008 and 2011. Nymphoides peltata was governed by sodium and alkalinity in both the years. Trapa natans and Azolla cristata were not governed by any of the selected environmental variables. The distribution of Alternanthera philoxeroides was affected by water depth, magnesium and calcium, and this affect was however, variable for the years 2008 and 2011. The affect was more pronounced in the year 2011. In case of Trapa natans potassium, sodium and alkalinity were the key variables in 2008 while in 2011 alkalinity and potassium appeared to be more significant. 79 00 'o ON GO -2 73 ^ 3 c3 03 CO r-; 0) CO 00 a O 00 en O S-4 o ^^_^^ ^ o '>1) T3 X) CI cs 13 § o 00 O o O c5 o t/5 00 O O CO T3 4-» G CaO 13 CD •^ .s ^3 d o 1 00 J3 H Cli nS _c o 3 "o3 C3 ^ o s ttf t+^ en -o o (U -4-J 3(S o o ]"4-» Cu 'co 'S> O • CI ^ Ci. 5S ) o OH O CO T3 • ,, <+-( O § \ CO fi 1 1— 1 —1 1 —1 u 80 01.- su ta 03 X>). U T3 D J3 (L) 00 -*-• -*c^S C O "^ ;g •S .S bi "COi ^->H> -0S3 3 i> -•-' > (U \0 -JS D (N Si 03 o --^ -r ^ O^ JL>> •3 -a ^ 3c CSS 'U^; O 00 O o o ^^ O o = g "^ D, -S .s :s 3 (D *" 2 "5^ is bO 1 X -' S a^^ S +j CS <+^ '^ -XS O S? —oH ^CO ^-t-°" ^ 'C 'w d 5 ° § S ^ ^ (U 73 O 'S S S T— O CO CO ^H VH •-H .rt O c« > -t! !^ C S^ 13 S ^ d c« "^ -.OX) uO •->- o H a - ^ S c« •> d O !> O o .Si > CPSI («U (N (U tn 00 O !-i t-; VH T—( tn wo f_^ > o r3 S ;3 03 ^i %-i O o 00 O (/5 CD ?^ a O o' TiS +-• •4-» ^ Til X) rl cd ^ o 1 C O ^ ^3 3 O o o 6 t^-l T:! O (U O o -§ •l-> a SH CO > O o !3 >-. C! O rt u > a CO s rs >, D o x CO > (U n T3 o rt d -*-> o -t-" a >;s M o (1) o "3 o o;-i o > U CO T3 •• <+-! c3 o fj •^^ c Ti a a '•S _o ^ o^ ^ "u 0'^0 '+_>3 l-H o 00 CO (U .'-*-s» ki el ^_^ 3 1-H o o o (N ao TS 0) d o CS § 00 73 O OT o aj d 3 •(-' 43 c3 a O k4 O 3 -^ <+H O -t03i -!-3i „ O CO o 3 "^ o • »-4 cd G ^ > _o c ,__, +-» q T3 S 'g S-( d 2 •»" O S a tn S o ^0) 'S!S "cS o ^ "rt 'B *3 -^ o •5 C C/3 S 1) C ^CS^J Ti^; 5-01 <;- s=^ ?: o CO C 0 T3 1—1 •^ r; CO o u "3 DC a i § s-§ Table 3.15; Eigenvalues, percentage variance and total inertia of the canonical correspondence analysis (CCA) axes between the species and environmental variables for different seasons and overall for year 2008 and 2011. Cumulative percentage Total Eigen values variance inertia Axesl Axes2 Axes3 Axes4 Axesl Axes2 Axes3 Axes4 Spring 2008 0.368 0.215 0.132 0.100 41.5 65.8 80.7 92.0 0.887 Spring 2011 0.381 0.208 0.166 0.094 40.6 62.8 80.5 90.5 0.938 Summer 2008 0.389 0.194 0.110 0.073 47.9 71.8 85.4 94.4 0.812 Summer 2011 0.366 0.140 0.097 0.064 51.8 71.6 85.3 94.4 0.706 Autumn 2011 0.415 0.211 0.105 0.101 47.6 71.7 83.8 95.3 0.872 Autumn 2008 0.476 0.211 0.128 0.091 49.8 71.8 85.3 94.7 0.956 Year 2008 0.417 0.172 0.115 0.087 49.6 70.1 83.8 94.1 0.841 Year 2011 0.385 0.141 0.100 0.074 50.8 69.5 82.7 92.5 0.758 84 3.4 DISCUSSION Wular lake ecosystem sustains luxuriant growth of macrophytes belonging to all life forms viz., emergents, rooted floating, submerged and free floating. Present study documented 33 species which constitute the macrophytic flora of Wular lake. In an earlier study (Mir and Pandit, 2008) have reported 25 macrophytic species in the lake (based on their survey during 2002-2004). Most of the additional species recorded during this study are typical wetland species including Bidens cernua, Lycopus europaeus, Veronica anagallis-aquatica and Echinochloa crusgalli. This reflects terrestrialization of the lake littorals. The present study also reported invasion oi Alternanthera philoxeroides in the lake (Masoodi and Khan, 2012a). Species with emergent life form are predominant over rooted floating and submerged types. A simikir trend has been observed in all other lakes and wetlands in the valley as well (Reshi et al., 2008). The presence Azolla in Kashmir had only been reported recently (Pandh et al., 2005; Mir and Pandit, 2008). Azolla was first reported from Dal lake and in a very short time span, all the lakes and wetlands in the valley had become invaded. It seems that the introduced Azolla has generally been identified as Azolla pinnata, but without justification. The SEM photographs reveal the glochidia to be pluriseptate, with a distinct terminal anchor-like structure (Figure 3.6D). The number of septa range from 5-7 (Figure 3.6D); the megaspore perine structure is granular (Figure 3.6A) and the leaf trichomes appeared to be bicellular. These three characters are specific for A. cristata. (Evrard and Van Hove, 2004). In India, the indigenous Azolla species have sporocarps grouped by two and their megasporocarps contain nine floats, whereas their glochidia are not arrow-shaped, which indicates that they belong to A. pinnata. It must therefore be concluded that the samples we have collected from Wular Lake belong to an introduced Azolla species, indigenous in the Americas (Masoodi and Khan, 2012b). The chemistry of lake water and sediment is the indicator of catchment geology, weathering and erosional processes as well as anthropogenic activities. The results of the present study showed that physical weathering dominated over chemical weathering, resulting in enhanced rates of erosion and consequent deposition of huge detritus into the lake (Rashid et al., 2013). The granulometric characterisfics resuhs 85 revealed silt and clay to be the major constituents of the lake sediments. The overall soil type of the lake can thus be classified as 'sih-loam'. Silt and clay has been reported to be major component of waterbodies in Kashmir (Kaul et al, 1978, Trisal and Kaul, 1983). The higher percentage of sand at S5 is due to Madhumati river which joins the lake at this site. At other locations, where the river Jhelum leaves the lake, for example S2, the high percentage of clay indicates that the sediments transported and deposited by drainage waters mainly consisted of small size particles (< 20 \iTn) and clay may have been accumulated over the years. This additional clay does not seem to represent the most recent weathering product rather it shows the precedent detritus history. Water quality is affected by a wide range of human and natural processes that alter the biological, chemical, and physical characteristics of water. One of the most widespread water quality problems is nutrient enrichment, resuhing from the excessive use of fertilizers and pesticides in agriculture (UNWWAP., 2009; PAN, 2009). Increasing nutrient inputs to aquatic ecosystems lead to increasing concentrations of phosphorous and nitrogen in the water and in the substrate (Smolders et al., 2006). The cationic content of the waters revealed a predominance of mineral ions in the order of Ca>Mg>Na>K, with higher concentrations in winter and lower values in summer season in both water and sediment. Calcium is generally the dominant cation in Kashmir owing to the predominance of lime rich bed rock in the catchment area (Zutshi et al., 1980). The decrease in their concentrations in summer was due to consumption by macrophytes (Trisal and Kaul, 1983). A similar trend has been reported from other lakes in Kashmir as well (Trisal and Kaul, 1983; Pandit, 2002; Jeelani and Shah, 2006). Alkalinity and conductivity also depicted minimum values in summer due to removal of CO2 and HCO3 during photosynthesis by primary producers. The strong correlation of conductivity with calcium (r=0.81) and alkalinity (r=0.89) suggests these parameters to have a major influence on conductivity in Wular lake. The average pH in the lake during the entire study period was >7, indicating that the water's are well buffered in Wular lake. There are statistically significant differences in the mean pH of different seasons (p<0.05). The gradual increase in pH during summer was due to removal of carbon dioxide and protons from the water 86 column during photosynthesis by planktons and submerged macrophytes, thereby shifting the equilibrium between carbonic acid and less stable bicarbonates and monocarbonates. Lower pH during winter was because of increase in carbonic acid concentration on account of respiration exceeding photosynthesis. Phosphorus availability has long been recognized as a factor of paramount importance for the water quality of lakes (Hutchinson, 1957; Schindler, 1977; Reynolds 1884; Havens and Schelske, 2001; Paerl et al, 2001). Phosphorous enters the lake in either a particulate form, which can be directly deposited in the sediment, or as dissolved phosphate, which can be incorporated in organic matter by primary producers that eventually sink to the bottom in an organic form (Sondergaard et al., 2001). In Wular Lake, a general trend of decline in the concentration of inorganic phosphorous during summer months was owing to its utilization by primary producers. Besides, increase in temperature and pH during summer season is favorable for precipitation of calcium carbonate due to rapid carbon assimilation from dissolved bicarbonates and under such conditions phosphate ion is known to co- precipitate with carbonate (Wetzel, 1972; House et al., 1986; Driscoll et al., 1993; Golterman, 1995; Hartley et al., 1997). Nitrate nitrogen was present in higher amounts than ammonical nitrogen in Wular Lake. The higher level of nitrate nitrogen than ammonical nitrogen was because of preferential uptake of reduced ammonia than nitrate by plants so that lower levels of ammonia occur in water (Kalff, 2002). Three processes are known to contribute to nitrogen retention (the difference between N inputs and N outputs to a given freshwater body) viz., denitrification, sedimentation and uptake by aquatic plants (Saunders and kalff, 2001). Though denitrification is the primary retention mechanism of nitrogen retention followed by sedimentaion, macrophytes create an ideal environment for denitrification by increasing the supply of potentially limiting organic carbon and nitrate to denitrifying bacteria (Reddy et al., 1989; Weisner et al., 1994; Brix, 1997; Saunders and kalff, 2001). The gradient analysis of the physico-chemical features of water indicated that the 8 factors including Calcium, magnesium, dissolved oxygen, alkalinity, conductivity, ammoniacal nitrogen, potassium and nitrate nitrogen have strong loadings on PCA 1 explaining 49.37% of the total variation. Component loadings of 87 more than 0.6 have been considered for interpretation. Strong loadings on ammonical nitrogen, nitrate nitrogen, conductivity have been associated with agricultural runoff (Malik and Nadeem, 2011, Najar and Khan, 2011). Thus, PCA 1 represents agricultural runoff. The second component, which explains 21.51% of the total variation, has strong loadings on three factors including sodium, orthophosphate phosphorous and total phosphorous while the third component which explains 9.43% of the total variation represents chloride. The chloride content in water bodies is attributed to external source of organic pollution of animal origin, especially domestic sewage (Thresh et al., 1976). Thus PCA 3 represents domestic sewage. It has been reported that over 80 percent of the sewage in developing countries is discharged untreated into receiving water bodies (UNWWAP 2009). Organic carbon is important in the overall nutrient cycling in aquatic ecosystems (Kaul et al., 1978). The higher value in winter is due to accumulation of biomass of macrophytes after their senescence accompanied by a drop in temperature and water levels. The decrease in temperature lowers the process of decomposition which leads to a buildup of organic matter. The highest percentage of organic carbon at S5 is due to large coverage of emergents at this site, possessing higher content of structural fibers which are resistant to decomposition (Polunin, 1884). Besides, dense and extensive coverage of Salix plantation along the shoreline also adds huge quantities of litter to the lake. We observed that among the selected invasive species, the dominant plant species change during the vegetation period. Nymphoides peltata occurred throughout the vegetation period but dominated mainly from mid spring to mid summer at S3 and S4 in Wular Lake. Trapa natans dominated all the sites in the lake except at S5 where emergent species cover a large area. Azolla cristata was the most dominant species in autumn and winter at all the sites in the lake. Alternanthera philoxeroides was present more abundantly at S5, but can potentially assume nuisance proportions. The invasion success of an invasive macrophyte involves a combination of environmental factors and plants performance (Maurer and Zedler, 2002; Hastwell et al., 2008). Identifying the factors associated with the success of invasive species is helpful in predicting its invasion and controlling such species and to elucidate the interaction between invasive and native species in ecosystems (Pysek and Richardson, 88 2007; Funk, 2008; Xie et al, 2010). Our results reveal that Alternanthera philoxeroides utilises the resources differentially at temporal scale as to get the best of what is available, this gives an edge to the species to increase its abundance and thereby effective area occupied within the lake. Overall, calcium, magnesium and depth play a key role in distribution of Alternanthera philoxeroides. The effect of other variables varies with seasons. 3.5 CONCLUSION The present study demonstrates considerable temporal changes in the abundance and distribution of the macrophytic community in Wular lake. Among the selected invasive species, the abundance of Alternanthera philoxeroides is increasing rapidly and is a great threat to the overall biodiversity and services of this Ramsar site. The study warrants continuous monitoring of ^. philoxeroides in the lake. 89 CHAPTER 4 PREDICTING THE SPREAD OF ALLIGATOR WEED (ALTERNANTHERA PHILOXEROIDES) IN WULAR LAKE, INDIA: A MATHEMATICAL APPROACH Ather Masoodi, Anand Sengupta, Fareed A. Khan, Gyan P. Sharma (2013). Predicting the spread of alligator weed (Alternanthera philoxeroides) in Wular lake, India: a mathematical approach. Ecological Modelling 263, 119-125 Summary Alligator weed {Alternanthera philoxeroides) is an amphibious weed invading worldwide. The weed forms large floating islands of variable sizes in this lake. Monitoring of the weed for 4 years reveals that the total number of patches increased from 6 in 2008 to 82 in 2011 with total area of all patches increasing from 41.3 m^ in 2008 to 831 m^ in 2011. We did predictive modeling with four year data using a variable growth rate equation, to estimate the spread rate of the weed assuming the entire lake area available for spread. Our model suggests that this weed may potentially cover entire lake in 13-19 years from 2008. The robustness of the mathematical model was also determined and validated using data from the first three years and it was in coherence with the previous model. We do caution, the predictive spread model of ^4. philoxeroides presented here has a strong bearing to the uncertainties of climate change, nutrient loading and competition effects. The study warrants an urgent need for rapid action involving manual removal before it actually assumes bigger dimensions in the lake and the region as more than ten thousand households completely depend on the resources of Wular Lake, India. Key words: Alternanthera philoxeroides, invasive species, predictive modeling, Wular lake. 90 4.1 INTRODUCTION Biological invasions by non-native species have become a major environmental problem. Biological invasion is a multistage process that includes the acquisition of propagules of species in their native range, transport of these propagules to a new range, followed by their introduction, establishment and spread in the new habitat (Richardson et al., 2011; Blackburn et al, 2011). Invasive plants rapidly increase their spatial distribution by expanding into native plant communities (Richardson et al., 2000). Wetlands in particular are vulnerable to such invasions (Shea and Chesson, 2002). hivasive plants not only affect the biodiversity and ecosystem functioning of wetlands but also human use and enjoyment (Zedler and Kercher, 2004). Monitoring spread dynamics is crucial in assessing the impact of any invasive species (Wilson et al., 2009) especially in case of aquatic invaders. Though 6% of the earth's land mass is wetland, 24% of world's most invasive plants are wetland species (Zedler and Kercher, 2004). In India, wetlands account for 15.26 million hectares area (Panigrahy et al., 2012). Large number of terrestrial and aquatic exotics have become naturalized and have affected the distribution of native flora to some extent, only a few have conspicuously altered the vegetation patterns in India (Sharma et al., 2005). Aquatic weeds are a major problem in most of these wetlands because of their exponential growth potential (MoEF, 2010). Eichhornia crassipes, Pistia stratiotes and Alternanthera philoxeroides are among aquatics invaders, that have posed serious threat to the native flora across the world (Zedler and Kercher, 2004). Alternanthera philoxeroides (here after referred as A. philoxeroides) has very recently invaded Wular Lake, a high altitude lake in Kashmir, India (Masoodi and Khan, 2012). Establishment of even a single alien plant species in such systems can radically transform their structure and function (Pysek and Richardson, 2010). Projecting the population trend is important for the management of an invasive species (Lee and Gelembiuk, 2008). A. philoxeroides is a perennial, amphibious herb native to South America and capable of aquatic and terrestrial growth (Julien et al., 1995; Pan et al., 2007; Jia et al., 2008). A. philoxeroides was introduced in India in the mid of the 20* century, around 1940's (Maheswari, 1965), and has now spread throughout the country (Pramod et al., 2008; Masoodi and Khan, 2012). A. philoxeroides reproduces vegetatively and thus 91 spreads rapidly forming dense floating masses (Maheswari, 1965). In aquatic situations floating mats can cover waterbodies, restricting human use, excluding desirable plant species, interfering with aquatic ecology and restricting water flow (Julien et al., 1992; Holm et al., 1997; Ma and Wang, 2005). Young shoots and leaves of ^. philoxeroides are eaten as vegetable and for medicinal purpose in many parts of the world, especially in South East Asia (Scher, 2004; Swapna et al., 2011). Despite all the benefits of ^. philoxeroides it is considered as one of the important threats as it decreases plant diversity and disrupts the ecological functions in invaded sites (Shen et al., 2005; Bassett et al., 2012). In Australia it is a 'Weed of National Significance' because of its negative impact (Burgin et al., 2010). In India, it is a growing concern in many of the water bodies (Sushilkumar and Yaduraju, 2003; Varshney and Sushilkumar, 2008), but temporal spread dynamics of ^4. philoxeroides have not been studied. Despite the recognition of A. philoxeroides as an important invasive species (Wang et al., 2008; Masoodi and Khan, 2012), many areas of the world lack basic information about the expansion of this species in the lake systems. For example, no information is available on the expansion of this species in Indian lakes. We hypothesize that invasive spread of A. philoxeroides in Wular Lake can lead to formation of dense floating masses rapidly. To test this hypothesis we examined the expansion of A. philoxeroides in terms of its patch area and at what rate these patches are increasing in size at Wular Lake. We developed a predictive model using the above mentioned variables to estimate the potential time frame for its spread (assuming the total lake area available for spread). The working hypothesis for the modeling exercise are (i) the growth of patches of different sizes is independent of each other, (ii) the rate of growth of a given patch (of a certain mean size) at a given time is proportional to the total number of similar patches present at that epoch and (iii) the rate of growth of all patches is directly proportional to the available uncovered area of the lake surface. We anticipate that results from this study might be useful in predicting a future epoch where significant portion of the lake will be covered by this weed and in supporting decisions to be made in context to management of this species. 4.2. MATERIAL AND METHODS 4.2.1 Study area The details of the study area are discussed in chapter 2.1. 92 4.2.2 Sampling The present study was initiated in 2008 and is a part of the long-term study of the floristic diversity of Wular lake. A total of 33 macrophytes have been identified in 2008 survey including A. philoxeroides (first report of A. philoxeroides from this lake). Sampling was undertaken at the peak growth period of A. philoxeroides, during the month of July for all the years. The locations of all areas of A. philoxeroides were recorded using a GPS (Garmin Etrex) and patch sizes were measured and a distribution map was generated using Arc View 3.2 software. The study was repeated in 2009, 2010 and 2011. at the same time corresponding to the peak growth period. 4.2.3 Predictive analysis A. philoxeroides forms floating islands of different sizes in the lake, so we divided them into 4 groups viz. l-5m , 6-10 m , 11-15 m andl6-20 m . We chose a median value of area for each group viz. 3m^, 8m^, 13m^ and 18m^ respectively and multiplied it with the total number of patches in each group to work out the total area of the infestations. We treat the four patch sizes as separate entities. The number count of the /-th patch as a function of time t is represented by the symbol n^ (t) where the subscript i G {1,2,3,4}. The average patch area a; of these entities is given (Table 4.1). The rate at which the t-th patch proliferates depends on two factors: the total number of patches and the fraction of uncovered area of the lake. The rate equations for each of these patches can be written as a set of four coupled differential equations as given below: dnj(t) KjiiiCt) i - 2^ 3; njCt) {1,2,3,4} (1) dt The various symbols in equation (1) and elsewhere in this paper are explained in Table 4.3. The term within the square bracket on the RHS of the equation is the uncovered area of the lake at any given instant f available for the expansion of the patches. Note that although cross-terms of the form niUj.i i^ j do appear in equation (1), their presence should not be interpreted as competition between the patches. They appear naturally when one tries to model the instantaneous area available to the patches for 93 expansion. We need to solve Equations (1) for rii^t) after determining the unknown rate constants Ki from observational data as explained below. At early times, one can safely assume that the total covered area of the lake is much smaller in comparison to the total lake area; i.e., A^ » Zpi^^ Oj(t), which implies that effectively the entire lake is available for the weed to proliferate. Under such assumptions, the above Eq. (1) not only takes a simple form Eq. (2): dUi A, -ir=Ki^ni (2) at Ui but also, becomes an uncoupled set of equations (which means that at early times, each of the different patch sizes can grow independently of each other). This has two very important consequences: on the one hand it becomes trivial to write down the analytical solution at early times: n^{t} = UQJ e ' "^^ but are also useful from the point of determining the numerical value of the (as yet) unknown constants K^ from a regression analysis using the observed data of the number of patches between the period 2008 - 2011. Once the growth rates K^ for the four entities are determined (Table 4.2), we can plug them back into Eq. (1) above and evolve the set of coupled differential equations using a standard fourth order Runge-Kutta integrator, for late times with the boundary condition set as -n^it — 0)= n^^^ (epoch t = 0 in this context refers to the year 2008). For the predictive model we assume that the nutrient availability does not vary at the temporal scale and the climate potentially remains constant. We use a standard nonlinear least-squared Marquardt-Levenberg algorithm to fit the set of observed data points (number of patches as a function of time) to determine the parameters n^^ and K, A^/a^ for i - ll,2,3,A}- The best fit parameters and the root mean square of the residuals (defined as square root of the reduced chi-square) is tabulated in Table 4.2. These values are then used to evolve the set of equations in time. We define a critical epoch T^Q to be the time it takes for the patches to cover 90% of the lake area. We end this section with a couple of remarks on the evolution of the patches. It is easy to predict qualitatively the nature of spread of these patches - the growth rate of each patch gradually decreases as the available area of the lake shrinks. At t » 0, one expects this to be a steady state for all the patches when the lake is fully covered by the 94 weed (see Figure 4.2). Further, the model is very sensitive to the determination of initial growth rate of the largest patches (median patch area 18 m) where the number of observations is the least. We feel that a couple of further observational points for patches of this size will make the model more robust and the prediction more accurate. The model choice stems from our observation of proliferation of patches between 2008-2011 and was constructed by following the exponential growth models in spirit. The model starts off with an exponential growth for the patches of given average sizes when the fractional uncovered area of the lake is close to unity. As A. philoxeroides gradually covers the lake, this exponential behaviour automatically changes to a steady decrease in growth rate in our model. Physically, this is akin to a competition between the patches to proliferate in the available uncovered lake surface. 4.2.4 Statistical analysis The patch size time series was analyzed using Gnuplot version 4.2 (www.gnuplot.info) and the model parameters were determined using an implementation of the nonlinear least-squares (NLLS) Marquardt-Levenberg algorithm built into this software (Williams and Kelley, 2007). 4.3. RESULTS The spatial distribution of A. philoxeroides patches in Wular lake from 2008- 2011 is shown in Fig. 4.1. In 2008, there were only 6 patches of A. philoxeroides. The total area of all these patches was 41.3m^. The largest patch recorded at 34°23'07" N and 74°32'56" E co-ordinates had a size of 12m . Three patches were in the group of (6-lOmO area. In 2009 the total number of patches increased to 21 and the total area estimated at 163 m . The number of patches in the group (11-15 m ) increased to 7 in this year while there was only one patch in 2008 and in 2010, there was almost a 4 fold increase in the number of patches in this range (Table 4.1). The total area of all the patch size groups in 2010 was 484 m . In 2011, the total area under A. philoxeroides infestations was 831m and the total number of patches was 82 (Fig. 4.1). The number of patches in the group (16-20 m ) increased from only one in 2010 to eight in 2011. The values of growth rates obtained from the regression analysis and other parameters are given (Table 4.2). As seen in Fig. 4.2, after sufficiently long epoch, the growth rate for all the four types of patches decrease. This is expected from the fact that 95 the lake surface gets progressively covered by A. philoxeroides. In other words, we run out of available area in the lake for new patches to form - leading to this limiting behaviour of ni{t). The resuUs project that potentially A. philoxeroides will cover the entire lake in the next 13-19 years starting from 2008 (Fig. 4.3). As an exercise to check the robustness of our mathematical model, we determined the parameters UQI and KiAi/di for i = {1,2,3,4} using data from the first three years. Data from the fourth year was kept as a test sample to check if it agreed with the model predictions within error margins. As shown in Fig. 4.4, one can see that for this exercise, while the overall numbers for T^Q are different from those when data from all four years combined, data point for the fourth year agrees well with the model prediction. We feel that this lends ample credibility to our method, although the precise numbers for T^Q predicted by the model remains sensitive to the availability of observational data. As noted elsewhere in this paper, future observations - even for a couple of years more will make the initial rate estimates and predictions more robust and accurate. 4.4. DISCUSSION Disturbance is known to facilitate colonization, establishment and spread of invasive plants (Schooler et al., 2010; Dong et al., 2012). A. philoxeroides forms large floating islands in Wular Lake (Masoodi and Khan, 2012). Fragmentation of A. philoxeroides patches in Wular lake results from the disturbance created while harvesting of nutlets of Trapa natans (for use as food) and Nymphoides peltata (for use as fodder) besides fish, by the locals. During the process they cause agitation oi A. philoxeroides floating islands promoting its fragmentation. Survival potential of A. philoxeroides fragments is attributed to its ability to withstand moderate damage (Liu et al., 2004) and possess a robust sprouting ability even after getting exposed to cold and dry winter season (Wilson et al., 2007; Liu and Yu, 2009; Dong et al., 2010a, 2010b). Wular Lake is characterized with seasonal water level fluctuations and the large floating settle on the sediment along the littorals (Figure 4.6). The young buds are protected from the extreme cold in winter by dense root mass (Figure 4.7) and adaptation of .4. philoxeroides to these changes makes this species an efficient invader of such systems (Liu and Yu, 2009). The area under A. philoxeroides has rapidly increased from 41.3m in 2008 to 831m in 2011. The increase in the number of A. 96 philoxeroides infestations from 6 in 2008 to 82 in 2011 can be explained by the ability of its fragments to survive and establish new patches. The results can be corroborated by the fact that A. philoxeroides patches have the potential to horizontally grow Im to 3m in one growing season and almost 4.3 m annually (Sainty et al., 1998; Clements et al., 2011). In China, the rapid range expansion of Alternanthera has resulted because of dispersal of clonal fragments (Pan et al, 2007). The results of our mathematical projection of the A. philoxeroides spread are based on the real time data of spread of the weed over four years from 2008-2011 in Wular lake. The lake will potentially be covered by alligator weed in 13 to 19 years starting from 2008. Validation of the method using three year data also corresponded to similar observations, with the fourth year data lying well within the projection range. Change in the projection values from 13 to 19 years with 10 to 14 years in the validation test can be attributed to limited sample size of the 18m^ patch for the year 2010. We due caution that the Wular lake is an extremely dynamic system and this projection of A. philoxeroides expansion however having a strong bearing subject to the uncertainties of climate change. One basic limitation of our mathematical model is the lack of a variable which models the transitions between different patch sizes. For example, with time the individual patches are expected to grow in size and this growth should be proportional to their respective sizes and available nutrients. After more careful observations over several years, one can refine this model by introducing such variables too. In Argentina, A. philoxeroides shows different growth patterns which has been attributed to varietal differences (Jia et al., 2010), but our model will not be affected as in Wular lake we only have one variety of A. philoxeroides. Adaptive plasticity of growth related traits {viz. biomass and main stem length) due to dynamically changing environmental conditions can affect the grov^h patterns of ^. philoxeroides and enable the species to occupy different habitats, which may contribute to successful invasive spread locally over time (Liu et al., 2011). Also presence of other species in the lake may influence the growth performance of ^4. philoxeroides through competition and other indirect effects. These need to be further investigated through in-situ experimentation and the results may be incorporated to refine the model. 97 The results reveal that A. philoxeroides has a tremendous potential for growth and spread in this Himalayan region. There are a large number of other lakes and wetlands in the valley and most of these are hydrologically connected. This puts them at high risk of invasion by A. philoxeroides as flowing water is the most potent dispersal agent and acts as 'conveyor belt' for moving propagules rapidly (Barrett et al., 2008; Okada et al., 2009). It is interesting to note that from 2008-2010, the weed was confined within the lake. However in 2011, the weed was observed growing on terrestrial area, along the banks of the lake near Watlab ghat, a village on the lakeshore (Figure 4.8). A. philoxeroides has invaded both terrestrial and aquatic systems including lawns, croplands, gardens, wetlands, rivers, and lakes, causing great economic and environmental problems in China (Ma and Wang, 2005). Pertinent to mention that Wular lake is the only source of livelihood for more than 10,967 households living along its shoreline (Anonymous, 2007). 4.5. CONCLUSION The results from this study warrant an urgent need for an ''early control and early eradication'' program that would potentially keep A. philoxeroides at the lowest possible level. In fact, at present we can aim for manual eradication as this invasive weed is in an early phase of invasion. If a maintenance control program is not initiated, the rapid expansion of ^. philoxeroides will put into question the ecosystem services of Wular Lake. 98 Table 4.1. Number of patches of A. philoxeroides in Wular lake during 2008-2011 / a,(m^) Number of patches observed 2008 2009 2010 2011 1 3 2 8 8 14 2 8 3 6 13 27 3 13 1 7 26 33 4 18 0 0 1 8 Table 4.2. The values of growth rates obtained from the regression analysis and other parameters. i aj m "C,i Ki AJa^ Root Mean Square Residuals 1 3 2.817 ±1.038 0.5434 ±0.1553 0.8943 2 8 2.933 ± 0.063 0.7402 ± 0.0087 0.0554 3 13 2.254 + 1.534 0.9338+0.2585 1.9135 4 18 0.162 + 0.067 1.2991 ±0.1514 0.3309 99 Table 4.3. Various symbols in equation 1 and elsewhere in this chapter are explained below: Symbols Explanations Hj (t) The number of patches of i-th variety at a given epoch t. Note that we have 4 different patch varieties - thus the index i can take values 1,2, 3 and 4. The average area of patches of the i-th variety (it's a constant). The total area of the lake. Kj Growth rate for the patch of i-th variety (determined from observational data using regression analysis). j^. Qj. £^ The rate of change of the number of patches of the i-th variety ' dt nj(t = 0) or HQJ This is the boundary condition for solving our set of four coupled differential equations. This symbol means the number of patches of the i-th variety at the beginning of observations, i.e, at t = 0. Tgo The time since the beginning of observations that it takes to cover 90% of the lake surface with A. philoxeroides. 100 -> Position of Wiilar lake 2008 2011 2010 Infcttttion size tn meter iqutre 3 8 9 Kilometers 13 18 Figure 4.1. Distribution and increase in number and size of A. philoxeroides patches in Wular Lake from 2008-2011. 101 :: 3 sq m. patches • 8 sq m. patches • 13 sqm. patches 18 sqm. patches 6 8 10 12 14 20 Time since 2008 / years Figure 4.2. Evolution of the individual A. philoxeroides patches as a function of time. The time evolution of the four patches (of different mean area) is plotted. As the lake surface is covered up, the rate of growth for each of the patches decrease and for ' , it approaches steady state, as expected. The model is very sensitive to the determination of parameters - especially those of the largest average patch size. A few more years of observation will make the model more robust and the predictions more accurate. 102 10 p Data Model Prediction 6 8 10 12 14 20 Time since 2008 / years Figure 4.3. The fractional area of the Wular lake that is covered hyA. philoxeroides as predicted by the numerical model. The fraction of the lake area covered by weed is plotted against time. The critical epoch j defined as the time since 2008 it takes for the weed to cover 90% of the lake surface is also marked. The solid curve corresponds to the best-fit parameters (in Table 4.2) of the growth rate of weed patches of various sizes as determined from the observations. The shaded area corresponds to the uncertainty in the determination in the parameters, which translates to the error bar on the prediction of 7 . We predict that the lake area will be covered by weed between 13 and 19 years. 103 lU 1 1 1 1 1 Data ^'^ i •[ Mooei rreoiciion 10' f i h .-•2 E^o f 1 ~ 0^ I > [ o / J i - i CoO *^ ^ -41 1 - CD f i_ •- ! - CO r [ 1- >s >%; ^ -5 Cf) t i 7^ 10^ CD -t i _i T— •f— ! (• II II j o oi !- o> o>- 10"' 1- H i 7 i -7" 10 i - 1 1 1 1 1 1 ill 1 i 6 8 10 12 14 16 18 20 Time since 2008 / years Figure 4.4 The fractional area of the Wular lake that is covered by A. philoxeroides as predicted by the numerical model by taking the first three years data to determine the model parameters and using the fourth year data as a test sample. In this case, the model parameters are poorly determined compared to the case where all four years of observation are used (Figure 4.3). In this example, although '. is quite different from Fig. 3, the fact that the blinded data point from the fourth year agrees well with the prediction (within errors) helps to underline the robustness of our method and also the fact that the model parameters are sensitive to the availability of data in their accurate determination. 104 %jr'<* Figure 4.5: Alligator weed forms large floating islands in the lake. Figure 4.6: A patch of alligator weed has settled on the lake sediment in winter season and locals use it as a support on the marsh littoral area of the lake. 105 Figure 4.7: Dense roots protect the young buds at the nodes in alhgator weed during the extreme chilly winters in Wular lake, Kashmir. Figure 4.8: Alligator weed spreading in the terrestrial areas along the shoreline in 2011. 106 CHAPTER 5 ECOLOGY OF TRAPA NATANS, AN INVASIVE MACROPHYTE IN WULAR LAKE Summary The growth and phenology of Trapa natans was ascertained in Wular lake. Geographic Information System (GIS) was used to map the distribution of Trapa natans in the lake. Presently T. natans occupies an area of 18.34 sq km of the lake area. The largest beds are along the eastern side occupying 11.88 sq km area. The results reveal depth to be an important factor governing the distribution of Trapa natans in the lake. A rosette produced almost ten seeds a year and the maximum biomass of 652 g dw/m^ in the species was recorded in July. Vegetative growth and seed production are segregated in a season minimizing the competition between these two activities. The species has the ability to preserve its stands in the lake and maintain a high density by production of large, well protected nuts which germinate in the sediment. Key words: Trapa natans, Wular lake, biomass, invasive species 107 5.1 INTRODUCTION Rooted macrophytes are a connecting link between the sediment, water, and (sometimes) atmosphere in wetlands, lakes, and rivers. The most important function that plants serve is primary production. However, macrophytes are also involved in ecosystem processes such as biomineralization, transpiration, sedimentation, elemental cycling, materials transformations, and release of biogenic trace gases into the atmosphere (Carpenter and Lodge, 1986). Trapa natans is an annual, rooted floating aquatic plant found in freshwater lakes and wetlands. Under favorable conditions, it covers nearly 100% of the water surface and causes 95% reduction in the penetration of sunlight, which adversely affects submerged plants such as water celery (Vallisneria americana), clasping pondweed {Potamogeton perfoliatus), and Eurasian watermilfoil (Myriophyllum spicatum) and associated flora and fauna (Kiviat, 1993; Groth et al., 1996; Hummel and Kiviat 2004). The levels of dissolved oxygen under dense beds of Trapa natans are reduced significantly (Tsuchiya and Iwakumal993; Takamura et al., 2003). The thick floating mats impede navigation (Kaul et al., 1976; Hummel and Kiviat, 2004). Trapa natans forms floating rosettes and these rosettes have feathery leaf like structures suspended in water through which they absorb nutrients from water. Even if these rosettes are detached from the plant, they can survive and form seeds during the remaining season (Sculthorpe, 1971). This is an additional feature of Trapa natans which helps in its spread. The starchy nut-like fruit of T. natans and its cultivars have been used as food by people in much of the native range and are widely cultivated in Asia(Tanaka, 1976). Demographic studies using annual aquatic plants are rare (Center and Spencer, 1981; Groth et al., 1996), whereas extensive studies have been conducted on annual terrestrial plants. The response of aquatic plants is expected to be contrary to that of terrestrial plants because of the aquatic habitat (Sculthorpe, 1971; Barrett, Eckert, and Husband, 1993), and clonal growth, which is typical of many aquatic macrophytes (Room 1983; Harper 1977; Groth et al., 1996). Clonal growth multiplies the opportunities of a genet (genetic individual) for sexual reproduction. 108 Water chestnut is considered a pest in the U.S. because it forms extensive, dense beds in lakes, rivers, and freshwater-tidal habitats. The nut-like starchy fruits of T. natans have been used as food by people in much of the native range and are widely cultivated in Asia (Tanaka, 1976). In India it is a cultivated for its nutritional and medicinal value. Though T. natans is an invasive species in the region (Khuroo et al., 2007), it is a very useful resource and is extensively used as food. According to Lawrence, (1895), when the main crop of the valley was destroyed due to floods in 1893, it was the flour of T. natans that saved people from starvation. In Kashmir, T. natans is an invasive species (Khuroo et al., 2007) and is widely distributed in the lakes and wetlands in Kashmir (Qadri and Yousuf, 2005; Kumar and Pandit, 2006), however its home is said to be Wular Lake (Lawrence, 1895). Though many studies have been done on the ecology of Trapa natans from several parts of the world (Groth et al., 1996; Tsuchiya and Iwakuma,1993; Takamura et al., 2003), no such study has ever been conducted in Kashmir, especially Wular Lake, India. The main purpose of our study was to ascertain the phenology and growth of the plant in Wular lake from an ecological perspective. 5.2 MATERIAL AND METHODS 5.2.1 Study Area All the data were collected from Wular Lake. A detailed description of the study area is given in chapter 2. Data was collected from the 6 selected sites as shown in the map (Figure 2.1). Wular is an eutrophic oxbow lake with permanent water inlet and exit points. 5.2.2 Study species Trapa natans (Lythraceae) is a floating freshwater macrophyte native to tropical and subtropical Africa and Eurasia (Muenscher, 1944; Gleason and Cronquist, 1991; The Angiosperm Phylogeny Group, 1998; Crow and Hellquist, 2000). There appears to be a consensus among botanists that there is only one species of Trapa natans (hereafter T. natans) comprising two varieties: 71 natans var. natans L. and T. natans var. bispinosa Roxb. (Integrated Taxonomic Information System, 2003; Hummel and Kiviat, 2004). T. natans is an annual macrophyte and forms 109 rosettes of floating leaves, borne on aerenchymatous petiole. Rosettes are borne on long stems bearing early, deciduous leaves that are abscised and replaced after 15 days by highly dissected green structures developing from the leaf nodes. These feathery adventitious structures have been described both as roots (Sculthorpe, 1971) and as leaves (Muenscher, 1944; Vasilev, 1978). The inconspicuous white flowers are solitary and axillary and consist of four 8 mm (0.3 in.) long, white petals and four green sepals, 5 mm long, ovate, villous, especially in the middle portion. The fruit is a four-homed, nut-like structure about 3 cm wide that develops underwater. Fruits ripen in about a month and can remain viable for about five years (Kunii, 1988). Fruits overwinter on the bottom of the water body and germinate to produce new shoots the following season. 5.2.3 Water chestnut distribution mapping Geographic Information System (GIS) was used to map the distribution of Trapa natans in the lake. Indian Remote Sensing Satellite data (IRS-ID, linear imaging self scanning LISS III) of May 2007 with a spatial resolution of 23.5 m and survey of India toposheet were used in the study. The image was georeferenced using Earth Resource Data Analysis System (ERDAS) Imagine 9.0 software, assigning Universal Transverse Mercator with World Geocoded system (UTM WGS 84) projection parameters. Digitization of scanned image was done using ArcView 3.2 software. The locations of all the beds of T. natans were recorded using a Garmin Etrex GPS and then downloaded to ArcView 3.2. Every feature on the map was digitized using polylines, polygons and point features. The historical distribution map of T. natans was generated after consultations with the local elderly fishermen who have been fishing in the lake for more than 5 decades. An approximate distribution map of T. natans in 1960's was prepared by recording the distribution of the plant based on their memory. 5.2.4 Field Sampling Sampling was done every 4 weeks from April 2009 to September 2009 using a (Imxlm) quadrat and density of rosettes was measured. Rosettes that were half in the frame were counted while those that were less than half in the frame were left. We measured various morphological parameters viz., the rosette diameter, number of 110 leaves per rosette and area per leaf by sampling 10-15 rosettes randomly at each site. Rosette diameter was the distance between the foliar apices of the two longest opposite leaves. Area of the leaf was estimated by drawing the outline of the leaf on the milimetre scale graph paper. For measuring biomass, rosettes and the stem were harvested from 0.25m quadrats . The biomass samples were rinsed in tap water to remove any attached debris and dried at 105°C for 24 hours for measuring the dry weight. We also measured the depth of water at T. natans beds to work out the vertical growth limits of the plant. For estimating the total yield of fruits/rosette, marking method was applied using 10-15 rosettes at each site. Production was summed over a period of three months from July, August and September. Fertilized ovaries (seeds less than 1 cm in size and still without spines) were also counted as fruits. 5.2.5 Statistical analysis Influence of months and sites on the studied parameters of T. natans were separately analyzed by oneway ANOVA. Differences in the mean values of the selected parameters among different months and sites were tested by Tukey's HSD test (p < 0.05). All statistical analyses were performed using the R statistical package. 5.3 RESULTS 5.3.1 Historical and present distribution of Trapa natans Trapa natans is distributed widely in Wular lake. The current and historical distribution maps of T. natans are presented in Figure 5.1 and 5.2 respectively. Presently T. natans occupies an area of 18.34 sq km of the lake area. The largest beds are along the eastern side occupying 11.88 sq km area. The other major beds are along the western side (2.99 sq km), north-western side near Kehnusa (1.72 sq km) and in northern part along Lankreshipora village and Garoora, together occupying an area of 1.75 sq km. The total area occupied by T. natans in 1960's, approximately comes out to be 23.14 sq km. The largest beds have been along the eastern side of the lake measuring 12.74 sq km, the western beh measuring 4.2 Isq km, the north-western beds 111 measuring 3.36 sq km and the northern beds along Bandipora measuring at 2.83 sq km. The resuhs reveal that there is a loss of 4.8 sq km coverage area of T. natans over these decades. There is nearly 30% loss in coverage of the plant along the north western belts. The major belts of T. natans along the eastern side have shifted 1.78 km into the lake. Not much shifting has occurred along the western stands. This shifting of the Trapa natans stands into the lake has resulted in lowering the open water area ofthe lake. 5.3.2 Biomass There are large spatial and temporal variations in biomass at the selected sites in Wular Lake. Biomass ranged from 71 g dwW in April to 652 g dwW in July. The mean monthly values of biomass are 87.77 ± 10.55, 206.07±26.23, 517.03±67.55, 523.50±64.22 g dw/m in April, May, June and July respectively (Table 5.1, Figure 5.3). It decreased from July onwards and was 372.07±38.98 g dw/m in September, followed by decay of the meadows. All pair-wise monthly comparisons revealed significant differences in biomass (p<0.05) except between June and July (p>0.05). Among the sites the highest biomass was recorded at S3 in all the months (Table 5.2, Figure 5.4). 5.3.3 Rosette number The number of rosettes ranged from 10-42 Ivci' in Wular Lake. Rosette number increased from a minimum of 13.62 ±1.82 W in April to a maximum of 32.77 ±4.71 /m in July (Table 5.1). There was no change in the mean rosette number in August and then declined significantly to 27.77 ±3.97 in September (p<0.05). The pair-wise seasonal comparison of means reveals significant differences in the mean rosette number between months (p<0.05), except June and July which were not significantly different (p>0.05). Among the sites, S3 had significantly lower number of rosettes per unit area compared to other sites (p<0.05; Table 5.2) while as there \\'as no significant difference between other sites. The results of the study reveal that T. natans shows maximum density of rosettes at a depth range of 1.5m to 2.5m (Figure 5.5) and forms monospecific stands 112 in this depth range. This represents the maximum colonization depth of T. natans in Wular lake. Though the plant grows below this depth at some sites, but the number of rosettes is very low. 5.3.4 Rosette diameter T. natans rosettes start to appear on the water surface in early April and form dense mats by the end of May. Rosette diameter increased from April and stabilized in the month of July. It ranged from 9.4 cm in April to 43 cm in July (Table 5.1). The mean monthly values of rosette diameter are 11.41 ±1.15, 17.26 ±2.42, 22.77 ±3.81, 27.24 ±5.21 cm for April, May, June and July respectively (Table 5.1; Figure 5.2). There was not much difference in rosette diameter between July and August while it declined significantly in the month of September, with a mean value of 22.75±4.5 cm (p<0.05). The pair-wise seasonal comparison of means reveals significant differences in the mean rosette diameter between months, except July and august and between June and September. The rosette diameter was highest at site S3 ranging from 11.4-43.0 cm with a mean value of 28.02 ± 9.56 cm during the study period (Table 5.2) and was significantly higher compared to all other sites (p<0.05). 5.3.5 Area per leaf Area per leaf ranged from 17-51 cm and the mean monthly values ranged from 22.30 ±2.45 cm^ in April to 39.61 ±3.89 cm^ in July (Table 5.2). The compajrison of monthly mean values revealed significant differences between all the months except July and August and between September and May. Among the sites, S3 had significantly higher area per leaf of the rosette than other sites (p<0.05; Table 5.1). 5.3.6 Leaf number per rosette The number of leaves in each rosette increased rapidly during the growing season and reached the peak value in July. It ranged from a minimum of 9 leaves at SI in April to 44 at S3 in July. The overall monthly average values of leaf number per rosette ranged from 12.03± 1.59 in April to 27.63 ±5.65 in July (Table 5.1; Figure 113 5.2). The pair-wise comparison of means revealed that ail the sites had significantly lower number of leaves compared with S3 (P<0.05). There were no significant differences between other sites. The mean leaf number per rosette at S3 was 39.2 ±3.83 while the remaining sites had a mean value of (25.3±1.63). The comparison between months also reveals significant differences between all months (P<0.05) except July and August (Table 5.1). 5.3.7 Number of rosettes per plant The number of rosettes per plant increases from May and appears to stabilize in the month of July. Number of rosettes per plant ranged from 1 - 6 at all the sites in the lake while as the mean monthly number ranged from 1.33 ±0.55 in April to 4.23 ±1.07 in July (Table 5.2). 5.3.8 Fruit number per rosette Fruit formation in Trapa natans starts by the end of June and harvesting of fruits begins in July and continues for nearly three months from up to September. The mean number of intact fruits per rosette was 3.3 ±0.9, 3.9±1.4 and 2.4 ±0.7 in July, August and September respectively. Among the sites, the highest number of fruits per rosette were produced at S3 (Table 5.3). The average number of fruits per rosette was almost double in August compared to other sites, recording a mean value of 6.6 ±1.1. The average number of fruits in Wular Lake sums up to 9.6 ±2.9 per rosette. 5.4 DISCUSSION There is distinct zonation of vegetation in Wular Lake with Trapa natans forming dense stands at higher depths. The results of the present study reveal that the depth ninge at which Trapa natans achieves maximum density in Wular Lake ranges from 1.5-2.5 m (Figure 5.7). Though at some locations in the lake it does occur below this vertical limit, but does not form dense stands. T. natans has been reported to grow abundantly at a water depth of 2 m with soft muddy bottoms (Countryman, 1978; Bogucki et al., 1980). Below 1.5 m depth, Nympholdes peltata, the second most abundant macrophyte in the lake grows abundantly (Chapter 3; Table 3.2). Depth zonation is a typical feature of wetlands and lake littorals, with species occupying different portions determined by competition with other species and tolerance of 114 species to various environmental variables, prominently water level (Keddy, 1984; EUery et al., 1991; Clevering et al., 1996). Rooted plants are major components of most aquatic ecosystems and often dominate the biomass in shallow areas (Wetzel, 2001; Hummel and Findley 2006). It grows best in shallow, nutrient rich fresh waters with a pH range of 6.7 to 8.2 (Kiviat, 1993; Naylor, 2003). Trapa natans has an effective strategy to segregate vegetative growth and seed production in a season, hence minimizing the compethion between these two activities. Competitions for resources are vital in shaping up the life history strategies and lead to a trade-off between various structures (McGinley et al., 1987; Groth et al., 1996). The results reveal that the rosette diameter increases rapidly during the growing season. T. natans is characterized by a constant birth and death rates of individual leaves (approximately one leaf per day) with an estimated average leaf life span of less than 30 days (Hayashi, 1983; Tsuchiya and Iwaki, 1984). The remaining vegetative characteristics of the plant including biomass, rosette number and number of leaves per rosette also increase by the time flowering starts (Table 5.2). As soon as the flowering and fruit formation starts, allocation of resources changes from vegetative to reproductive structures. The vegetative growth appears to stabilize with no further increase in any of the morphological characteristic of the rosettes. Trapa natans grows better in nutrient rich and moderately alkaline waters (Papastergiadou and Babalonas, 1993; Kiviat, 1993). Rooted aquatic macrophytes absorb nutrients mainly from the sediment as well as from overlying water (Madsen and Cedergreen, 2002; Li etal, 2010). A characteristic feature of Trapa natans is to produce small number of fruits but comparatively larger in size than most other annuals (Kunii, 1988). Larger seed size than confers advantages in seedling establishment and survival, which is a challenge in aquatic habitats for species like T. natans (Fenner 1985). T. natans allocates nearly 36% of its total dry mass to reproductive structutres (Groth et al., 1996). The resuhs of the present study reveal that approximately 10 fruits are produced per rosette in Wular lake. The rosette diameter at S3 is greatest and also the fruit production is largest as compared to other sites (Figure 5.9; Figure 5.10). The variations in fruit number among sites might be due to varietal differences of the plant in the lake. Lawrence, (1895) had mentioned that there are a number of varieties of T. 115 nutans (locally called Singhara) in Wular lake, viz. Basmati, Dogru and Kangar. Basmati with small nut and a thin skin is a superior variety named in honor of variety of rice. This variety gives one third of Kernel for two thirds of shell. Dogru has comparatively a larger nut with thicker shell (Lawrence, 1895). The Kangar variety has a very thick shell with long projecting horns, and gives the least Kernel of all. Large quantities of T. natans fruits are harvested from the lake in two seasons (summer and winter) by locals residing in 31 villages along the fringes of the lake (Table 2.1; Figure 2.3). Fresh fruits are harvested from the rosettes during summer and a'portion of the fruits fall from the plant and sink to the bottom of the lake which generates the bed of Trapa natans at that site the following year. During winter, the nuts are gathered in a simple way. A boat is moored to a pole on the singhara ground, and two men rake the bottom of the lake with long poles to which are attached crescent-shaped hoes. They work in a circle around the pole by which the boat is moored, and scrape up a heap of nuts and mud (Figure 5.7). The mud is then beaten with a pole (chokdan) and a net (khushabu) is put down and the nuts are dragged into the boat (Lawrence, 1895). However, as a result of sedimentation and altered hydrology of the lake, this practice is changing at some sites (Figure 5.8). The results reveal that the dense stands of Trapa natans have moved into the lake over several decades. The shift has particularly been more pronounced along the eastern side wherein the stands have shifted nearly 2 Km into the lake over the last fifty years. River Jhelum enters is the largest contributor to the water inflows into the lake arid deposits large amount of sediment there. The vegetation in the lake affects the water velocity and hinders the transport of water column constituents, for example, the particulate matter, plankton and detritus (Abdelrhman, 2003). Water chestnut assumes significance because it sets the limits of littoral zone in the lake and ftarther enhances sedimentation of the lake by facilitating the settling of suspended solids 116 to considerable deterioration of the water quality of the lake. Besides construction of embanlcments for flood control along the eastern side has also contributed to siltation by preventing the farming of the sediments in the flood plains, which is consequently deposited directly in the lake. The study done by Wetlands International, (2007) has revealed a loss of one fifth of the water holding capacity of the lake over the last three decades, equivalent to annual lake sedimentation of rate of 2,470 acre feet. Salix plantation was raised by government agencies 50 years ago to meet the fuel wood requirements of the state. The results also reveal that area of Trapa nutans has reduced nearly 5 sq km in the last 5 decades. We believe that in future the rate of loss of area will be much faster because there is no more space left for Trapa natans to colonize and move on. Only the passage of the river is left, remaining area is already covered by vegetation. Our argument gains support from the observations in Hygam wetland, an IBA site (Important Bird Area) associated with Wular Lake. Hygam does not support Trapa natans anymore which is did some 30 years back (Kaul et al, 1980). 5.5 CONCLUSION The results from this study reveal that Trapa natans is decreasing in coverage owing to sedimentation of the lake and invasion by other species like Alternanthera philoxeroides. Management practices such as dredging should be considered in order to reduce the accumulation of sediment in the littoral zone and to prevent overgrowth of the floating-leaved macrophytes. 117 Bandipora Kehnusa Sopore I I Wular Lake I I Paddy cultivation I I Trapa natans •I Salix plantation Kilometers Figure 5.1: Current distribution of Trapa natans in Wular Lake. 118 Bandipora Kehnusa I I Wular Lake ^^ Marshy area I I Trapa natans Kilometers Figure 5.2: Approximate distribution of Trapa natans in Wular Lake in 1960's. 119 Table 5.1: Range, mean and SD of various characteristics of Trapa nutans in Wular lake. FLosette diameter, area per leaf and leaf number per rosette are of primary rosettes. LSD Parameter April May June July August Sept (5%) Biomass (gdw./sqm) Range 71-115 128-244 385-646 422-652 406-615 322-453 Mean 87.77 206.07 517.03 523.50 483.27 372.07 18.48 (±)SD 10.55 26.23 67.55 64.22 49.68 38.98 Rosette number/sqm Range 10.0-17 15-26 19-32 22-42 22-41 18-36 Mean 13.63 22.73 25.57 32.77 32.00 27.77 1.16 (±)SD 1.81 2.82 3.17 4.71 4.57 3.97 11.7- Rosette diameter (cm) Range 9.4-13.8 24.3 14-32.4 20-43 23-40 14-34 Mean 11.41 17.26 22.77 27.24 27.49 22.75 1.07 (±)SD 1.15 2.42 3.81 5.21 4.49 4.50 Area per leaf (sq cm) Range 17-28 25-41 31-43 34-51 33-45 25-42 Mean 22.30 34.10 36.87 39.61 39.17 32.77 1.40 (±)SD 2.45 3.39 3.01 3.89 3.24 4.42 Leaf No./rosette Range 9.-15 13-25 18-34 22-44 21-38 15-31 Mean 12.03 17.53 23.10 27.63 26.10 22.60 1.07 (±)SD 1.59 3.21 4.11 5.65 4.25 3.55 Number of rosettes/plant Range 1-3 2-5 2-5 2-6 2-5 2-5 Mean 1.33 3.13 3.83 4.23 3.63 2.87 0.43 (±)SD 0.55 0.73 0.91 1.07 0.81 0.90 120 40 "•" 1 E 600 - IT E W a- 35 500 - in 6 30 T3 2 D) 400 - 0) 25 4—' I 300 0) E to 20 g o -I- -0- ° 200 - 111 CO 15 100 - 10 1 1 1 1 1 1 ^ § (0 Q. < < o 45 0 0 E 40 8 ° 40 u 8 8 35 8 ^ 35 0 1 8 8 0) ^ § 0 30 8 —r o 30 1 _,- S 25 H 25 1 fi?^ 20 20 T^ 0 & ! 0 "^ o 15 0 15 H J. 1—1 -L "^ 1—H 10 10 1 1 1 1 1 1 1 1 1 1 1 1 c ^ §> 3 3 Q. 03 Q. a a § 0) < < ^ 0) < < CO CO 6 c (0 5 E o & 4 in ^- I (0 I 3 I abbI I a o 2 n < d 1 4 D 1 r 1 r^ < < I I Figure 5.3: The box-plot of monthly variations in characteristics of Trapa natans in Wular lake. Box length is the interquartile range; whiskers give 95% confidence limits and open circles denote extreme values. 121 Table 5.2: Site wise mean monthly values of different parameters of the Trapa natans in Wular Lake. Rosette diameter, area per leaf and leaf number per rosette are of primary rosettes. Parameter Site April May June July August Sept Mean Biomass SI 82.4 212.4 474.2 597.0 549.6 374.8 381.7 (g dw/sqm) S2 89.0 209.2 426.8 464.8 471.4 359.0 336.7 S3 95.0 227.2 562.6 558.8 499.0 390.4 388.8 54 92.6 196.6 581.4 542.6 482.2 345.8 373.5 S5 83.2 192.6 533.8 491.4 433.2 403.6 356.3 S6 84.4 198.4 523.4 486.4 464.2 298.8 342.6 Rosette number/ sq m SI 14.0 21.6 28.8 35.4 35.4 32.6 28.0 S2 14.2 23.8 26.2 32.8 30.8 28.8 26.1 S3 12.4 18.4 21.2 24.0 24.4 21.6 20.3 S4 13.8 24.0 25.8 35.2 31.4 29.0 26.5 S5 13.2 24.4 24.2 34.2 34.8 27.6 26.4 S6 14.2 24.2 27.2 35.0 35.2 27.0 27.1 Rosette diameter SI 11.4 16.3 21.4 25.2 26.8 21.2 20.4 (Cm) 32 10.9 17.9 21.7 24.8 25.1 22.4 20.5 S3 12.7 20.8 29.8 37.4 36.6 30.8 28.0 S4 11.1 15.7 20.0 25.5 25.2 19.8 19.6 S5 11.1 16.3 22.5 24.5 25.4 21.3 20.2 S6 11.3 16.5 21.2 26.1 25.8 21.0 20.3 Area per leaf SI 23.2 35.2 38.6 41.8 40.0 36.2 35.8 (sq cm) S2 21.2 29.4 37.0 40.0 39.6 33.6 33.5 S3 22.4 35.2 40.0 43.0 42.8 38.0 36.9 S4 21.4 35.4 36.4 38.2 38.2 29.0 33.1 55 21.6 33.6 33.0 36.4 35.0 29.4 31.5 56 24.0 35.8 36.2 38.2 39.4 30.4 34.0 Leaf No./rosette 51 10.4 15.2 20.2 24.2 23.2 21.6 19.1 S2 11.2 15.6 21.8 25.2 25.8 20.8 20.1 53 12.6 22.8 31.0 39.2 34.0 28.6 28.0 54 12.0 18.0 21.4 26.6 24.2 20.8 20.5 55 12.8 17.2 22.0 25.0 25.2 22.2 20.7 56 13.2 16.4 22.2 25.6 24.2 21.6 20.5 No. of rosettes /plant 51 1.4 3.2 4.2 4.6 3.6 3.4 3.4 52 1.4 3.2 4 4.2 3.8 2.8 3.2 53 1.2 2.6 3 3.4 3.2 2.6 2.7 54 1.6 3.4 4.4 4.8 4.2 2.8 3.5 55 1.2 3.2 3.6 3.8 3.2 2.4 2.9 56 1.2 3.2 3.8 4.6 3.8 3.2 3.3 122 Apr May Jun Jul Aug Sep Figure 5.4: Site wise mean monthly values of different parameters of the Trapa natans in Wular Lake. Rosette diameter, area per leaf and leaf number per rosette are of primary rosettes. 123 40.0 35.0 30.0 01 25.0 E 3 20.0 C a 15.0 0) Figure 5.5: Mean number of rosettes (per sq m) in Trapa nutans at different depths in Wular lake. 124 Table 5.3; Number of fruits per rosette from July to August. Sampling number is given in parenthesis. SI S2 S3 S4 S5 S6 LSD (5%) July Mean 2.8 (14) 2.6 (10) 4.8 (10) 3.6(15) 2.4(12) 3.6 (14) 0.84 SD 1.1 1.1 1.5 0.9 1.1 0.9 August Mean 3.6(12) 3.4(10) 6.6 (10) 3.6(15) 2.6(12) 3.6(13) 0.67 SD 0.9 0.5 1.1 0.9 0.9 0.9 September Mean 2.4 (9) 2.0(8) 3.6(7) 2.8(15) 1.6(8) 2.0(10) 0.54 SD 0.5 0.7 0.9 0.8 0.5 0.7 Figure 5.6: Fruit number per rosette in Trapa natans from July to August in Wular Lake. 125 Figure 5.7: Trapa natans near its peak biomass in July 2010 at station 1 Figure 5.8: Decomposing Trapa natans at the same station, November 2010 126 Figure 5.9; Trapa nutans forms very large rosettes at S3 Figure 5.10: A rosette at site S3 with 44 leaves and 43 cn^ rosette diameter. 127 CHAPTER 6 MORPH RATIO, MATING PATTERN AND INCIPIENT GENDER SPECIALIZATION IN NYMPHOWES PELT AT A - AN INVASIVE SPECIES IN WULAR LAKE OF KASHMIR Summary Nymphoides peltata is a very wide spread invasive species growing in lakes and wetlands of Kashmir. The species is distylous showing pin and thrum morphs in its populations. Nymphoides peltata exhibits tremendous vegetative growth which interferes with the efficiency of sexual reproduction. The vegetative or clonal proliferation resuhs in biased morph ratios as a result of which chances of mating are reduced. Results reveal that the syndrome of heterostyly in the species is equipped with the barrier of self incompatibility. Populations where only pin morph individuals were encountered displayed low values of reproductive success while as populations which showed isoplethy with random distribution of individuals of the mating morphs, had high reproductive success, proving the negative frequency dependent reproductive success Nymphoides peltata. Interestingly, intermorph crosses where pin morphs served as female partner showed almost double seed set as compared to thrum. The species displays remarkable incipient gender specialization with thrum morph individuals showing more tendency towards maleness where as pin morph affiliated more to femaleness. The distyly in the species is potentially evolving into dioecy with pin morph individuals converting into female and thrum morph individuals into male individuals. Key words: Dioecy, Distyly, Heterostyly breakdown, Incompatible, Rhizomes, Invasive species, Nymphoides peltata 128 6.1 INTRODUCTION Invasive plants display enormous diversity in their modes of reproduction, affecting several aspects of the invasion process including biogeographic success, demography, and opportunities for evolution as local adaptation (Barrett, 2011). Reproductive systems are evolutionary labile and transitions among different modes fostered by invasions happen (Barrett, 2008). Studying the reproductive system of an invasive species is crucial for understanding the demographic and genetic characteristics of populations for better understanding of ecological and evolutionary concepts (Blumental, 2005; Parker, Burkepile and Hay, 2006; Elam et al., 2007; Raghu et al., 2007; Sax et al, 2007; Rout and Callaway, 2009). Such concepts might also be quiet useful for predicting how invasive species are likely to respond to future environmental challenges. Nymphoides peltata-an aquatic macrophyte known for its invasive potential throughout the world, is invasive in Kashmir as well (Khuroo et al., 2007). The earliest reports of its presence in Kashmir dates back to 1924 (Vander Velde et al., 1979). The species is a prolific invader of eutrophic lakes and water bodies (Vander Velde et al., 1979). This species has high biomass productivity and a high leaf- turnover rate (Brock et al., 1983; Tsuchiya, 1991; Marion and Paillisson, 2002), and individual genets often occupy a large area through extensive clonal growth. The plant is harvested and used for fodder in the Kashmir Valley (Langar and Bakshi, 1990). It is a distylous species showing sexual polymorphism where populations comprise of short styled thrum morphs and long styled pin morphs (Ganders, 1979; Lloyd and Webb, 1992a; Wang et al., 2005). Normally this sexual polymorphism is associated with a number of morphological and physiological characters such as polymorphisms of stigma and pollen between the different organ levels and very often with a self-incompatibility system (Barrett, 1992). Among these characters the biochemical barrier of incompatibility attracts lots of attention (Matton et al., 1994; Harder and Barrett, 1995). Heterostylous taxa associated with physiological incompatibility system exhibit disassortive mating where individuals of one morph can mate only with the individuals of opposite mating morph (Barrett, 1990; Lewis and Jones, 1992; Lloyd and Webb, 1992a). This mating pattern drives populations to numerical equilibrium of isoplethy where pin and thrum morph individuals are almost equal in number (Lloyd and Webb, 1992b; Castro et al., 2007). The maintenance of 129 sexual polymorphism involves negative frequency dependent selection whereby a mating type's reproductive success depends on the frequency of the sexual morph with which it can mate (Thompson et al., 2003). Frequency dependent selection leads to an equal morph ratio at equilibrium (Heuch, 1979; Eckert et al., 1996; Clark et al, 1988; Finny, 1952). This numerical balance is having tremendous reproductive implications as it provides saturated mating chances for the two potential mating morphs. Therefore, as anticipated, at isoplethy (hlmorph ratio) the reproductive success of mating morphs is ideal and maximum. Alternatively ratios with unequal frequencies resuh when morphs show clonal growth or differ in their ability to mate with each other (Omduff, 1980; Philipp and Schou, 1981; Jacquemyn et al, 2002; Kerry et al., 2003; Wang et al., 2005; Brys et al., 2007). Nymphoides peltata also witness's prolific clonal proliferation via runners (Van der Velde et al., 1979). A single plant can colonize large areas in just a few years (Brock et al., 1983). In addition to vegetative reproduction from broken runners, secondary propagation occurs by plantlet development at the flowering stems (Omduff, 1966; Van der Velde and Van der Heijden, 1981). The ability to reproduce vegetatively is evidently an important part of the reproduction strategy in N. peltata since monomorphic and possibly genetically uniform populations occur (e.g. Uesugi et al., 2004; Wang et al, 2005). Clonal growth is anticipated to interfere with the normal sexual reproduction of the species, disturbing morph ratio, diluting compatible pollens, reducing mating chances, fruit and seed set (Omduff, 1966). Under such stressful conditions where selection forces favoring this syndrome are rare or eliminated, the characters associated with heterostyly are believed to break down to dioecy or homostyly (Ornduff, 1966). The relative importance of different reproduction strategies in A^. peltata like many other clonal aquatic plants is poorly studied (Wang et al., 2005). Clonal plants change their reproduction behaviour when introduced in small numbers, which makes predictions of reproduction at introduced sites difficult (Barrett, 1992). There is growing interest in exploring the modes of reproduction operative in different geographical locations (Peck et al., 1998; Keitt et al., 2001). Till date no such information is available about N. peltata and how it behaves in a high altitude Wular Lake, India. The present study was planned to analyze the relative importance of sexual vs. clonal reproduction of Nymphoides peltata in Wular lake and the presumed 130 evolutionary changes from distyly to dioecy or homostyly. A^. peltata is widely distributed in Kashmir and has invaded other lakes and wetlands as well. In order to get a better understanding of the reproductive strategy of the plant, we studied populations in other major lakes of Kashmir as well. The results of this study might potentially help in designing the effective management strategy for Nymphoides peltata in Kashmir. 6.2 MATERIAL AND METHODS 6.2.1 Plant material and study area Nymphoides peltata (Gmel.) 0. Kuntze (Menyanthaceae) commonly known as yellow floating heart or fringed water lilly, is native to Eurasia and the Mediterranean (NWCB, 2007) as well as China, India, and Japan (IPANE, 2003). It is however invasive in Kashmir (Khuroo et al., 2007). Unlike the majority of Nymphoides spp., which mostly occur in the tropics and sub-tropics, A^. peltata is the only species in the genus occurring in moderately cold temperate areas. Maturation of floral buds is underwater. The buds are raised above water surface for anthesis. The flowers are brightly yellow and showy, consisting of a short basal tube and five spreading corolla lobes, 3-4 cm in diameter. The flower edges are distinctly fringed (common name fringed water lily). Flowers are pollinated by a wide range of insect pollinators mostly bees and flies (Van der Velde and Van der Heijden, 1981). Few hours after pollination corolla withers, the pedicels deflect and subsequent fruit development is under water. In most lakes of Kashmir the species flowers from May to October (Kak, 1990). The fruit is a capsule upto 2.5 cm long containing many seeds. Apart from Wular lake, the study was also carried out in three major lakes of the valley viz. Dal lake, Nigeen lake and Manasbal lake wherein Nymphoides peltata grows abundantly. The Dal lake (34°04'56"-34%8'57"N and 74°49'48"-74°52'51"E) is about 2 km to the northeast of Srinagar city. Dal lake has a total water surface area of 11,4 km^ and is multi-basined with the Hazratbal (Bod Dal), the Lokut Dal, the Gagribal and the Nigeen as hs four basins. Manasbal lake (34''l4'40"-34°15'22"N and 74*^39'10"-74'^41'20"E) is the deepest lake of Kashmir, 32 km's northwest of the Srinagar city. The lake has an area of 2.80 km^ and the maximum depth is 12.5m. Nigeen lake (34*'07'46"-34'^06'26"N and 74°49'40"-74*'49'42"E) though referred to as a separate lake is actually a part of Dal lake. 131 6.2.2 EHstribution of Nymphoides peltata in Wular lake We prepared the distribution map of Nymphoides pelatata in Wular lake in GIS environment (the details of the methodology are given in chapter 5) and marked the populations in other lakes using a hand held GPS (Garmin ETREX). 6.2.3 Morph ratios in natural population We investigated 25 populations of Nymphoides peltata from all the major lakes of Kashmir (Figure 6.8). Each population was analyzed for floral morph ratio by sampling flowering ramets randomly (mean sample size 80, range 15-350). The range of sample sizes reflects variation in the size of populations. The populations were tested for pin thrum ratio and 1:1 isoplethy equilibrium. Individual fruit set, i.e. the number of flowers that set fruits in each plant, was assessed in at least 20 plants following the same procedure. The floral morph ratios in each population and heterogeneity among populations against the expected equilibrium 1: 1 ratio typical for distylous species was analyzed using G-test (Sokal and Rohlf, 1995). 6.2.4 Controlled hand-pollinations We conducted controlled hand pollinations on plants from six populations of Nymphoiodes peltata. During winter the rhizomes were collected randomly from Wular Lake (Figure 6.4) and grown in the artificial ponds. The experiments were conducted on caged plants both in the field in Wular lake and transplanted populations which were also caged. Shortly after beginning of anthesis, we did intermorph, intramorph and self pollinations for each experimental population and harvested fruits 12-15 days after pollination. The flowers were selected randomly for carrying out manual pollinations. For each of the three classes of pollinations, 6-10 replications were performed. 6.2.5 Morph ratio and fruit set The effect of morph ratio on fruit set was analyzed using different manipulated morph ratios. We used the experimental population of Nymphoiodes peltata growing in the artificial pond. Flowers were removed from the population early in the morning to create different morph ratios ranging from monomorphic to different biased ratios treatments were generated to test the effect on fruit yield. The ratios of minority 132 morphs were 0.1, 0.2, 0.3, 0.4 frequency. In one experiment, the pin morph was maintained equal to thrum morph in numerical strength (0.5-isoplethic equilibrium). The flowers were tagged with specific water resistant tags. The ratios were created to investigate the effect of morph ratio on seed set and to determine frequency dependence of reproductive success if any in the species. 6.2.6 Gender specializations In order to analyze the gender potential or gender bias if any affiliated with either morph, reciprocal crosses were made between the thrum morph and pin morph individuals. In one exercise thrum morph served as male parent and pin as female parent while in the other, pin morphs served as male and thrum morph as female. For both these classes of crosses, we had 12 replicates. In both type of crosses, seed set was analyzed and compared for the two morphs. 6.2.7 Vegetative reproduction by short overwintering rhizomes Wular lake is characterized by winter drawdown, the sediment of the major portion of the lake gets exposed (including the area where A'^, peltata forms dense stands). We laid Im quadrats at these stands and counted the number of short overwintering rhizomes in the Lake (Figure 6.3). In Manasbal lake, Nigeen and Dal Lakes a minimum water level is maintained, and we used Ekman-Birge dredge to harvest these rhizomes in 0.5 m quadrats during winter season. 6.3 RICSULTS 6.3.1 Distribution of Nymphoides peltata in Wular lake Nymphoides peltata is distributed widely in Wular lake, forming extensive and dense stands. Nymphoides j^e/Zofeoccupies a total of 8.17 sq km's of the lake area (Figure 6.7). The largest beds occupying 2.78 sq km area are along the south-eastern side bordering Shahgund and adjacent villages. The other major beds are along the north-western side all along from Bandipora to Kehnusa (2.46 sq km), and in northern part along Garoora, Lankreshipora and adjoining villages, together occupying an area of 2.93 sq kms (Figure 6.7). The depth at these sites of occurrence of A^. peltata ranges from 0.3-1.4 m. 133 6.3.2 Density of short rhizomes There was significant variation in the number of short overwintering rhizomes in the studied lakes in Kashmir (Figure 6.9). The highest number of short rhizomes was recorded in Wular lake with 43.60 ± 12.01 m' and the lowest number was observed in Manasbal Lake 18.67 ± 5.20 m"^. Dal and Nigeen lakes recorded 20.17 ± 7.03, and 27.50 ± 6.53 rhizomes m"^ respectively (Figure 6.7). The short rhizomes over-winter under harsh winter conditions in Kashmir, even when complete water drainage results in freezing of the substratum. These short shoots are whitish in color, situated laterally and are anchored in the bottom by roots (Figure 6.5). 6.3.3 Variations in floral morph ratios Floral morph ratios varied greatly among populations of Nymphoides peltata in the different lakes of Kashmir. Of all the populations studied (N=25), 36% populations were monomorphic (having flowers of either pin morph or thrum morph) and 44 % were dimorphic (represented by flowers of both thrum and pin morphs) (Table 6.1; Figure 6.8). Wular lake had 4 monomorphic populations, Dal lake had 3 while as Nigeen lake had 2 monomorphic populations. Manasbal lake did not have any mionomorphic population (Table 6.1). The dimorphic populations witnessed considerable heterogeneity with reference to morph frequencies especially in Wular Lake. Three of the 14 dimorphic populations deviated significantly from a 1 : 1 flower morph ration (G-tests with sequential Bonferroni criteria at p = 0.05), two of these were biased in favor of pin type and one in favor of thrum type flowers. Among the 9 monomorphic populations, 4 were of pin morph and 3 of thrum types. During the survey, no homostylous or unisexual flowers in either dimorphic or monomorphic populations of JV. peltata were recorded in Kashmir. 6.3.4 Mating system A clear-cut evidence of the strong dimorphic incompatibility system in Nymphoides peltata comes from the manual pollination experiments. Self and intramorph pollinations of the floral morphs resulted in very little fruit set whereas intermorph pollinations yielded more than 70% fruit set (Figure 6.10). The floral polymorphism in the species is thus equipped with a strong incompatibility barrier 134 which restricts self and intramorph fertilizations as evident from the results of the present study. 6.3.5 Floral morph ratio and seed set The results from the experimental populations in the pond revealed that the variation in morph ratio is having a great influence on reproductive success (Figure 6.11). The populations with isoplethy i.e. 1:1 ratio showed abundant fruit/seed set. Populations with biased morph ratios showed a declining trend in seed set in common morphs. This decline in seed set witnessed lowest values in monomorphic populations where some populations displayed zero seed set disproving the earlier belief that Nymphoides peltata is having a weak incompatibility system. Fruit set in pin morph declined with decline in thrum morph frequency and vice versa. The above trend approves the fact that N. peltata displays negative frequency dependant reproductive success where the reproductive success of one mating morph is determined by the frequency of other potential mating phenotype. 6.3.6 Potential gender specialization The two morphs pin and thrum differed significantly as for as femaleness and maleness is concerned. In crossing experiments where pin served as female parent and thrum as male parent the seed set was double as compared to crosses where thrum served as female parent (Figure 6.12). The crossing experiments revealed that thrum morph serves as a potential male and pin as potential female. The seed set in the two morphs differed significantly with pin morphs producing almost double number of ovules as compared to thrum morph. Thus A^. peltata shows distinct incipient gender specialization in its two morphs with thrum as potential male and pin as potential female. 6.4 DISCUSSION Majority of aquatic plant species show extensive clonal propagation along with limited sexual reproduction (Les, 1988; Barrett et al., 1993). Infact, clonal growth and propagation has generally been assumed to be more abundant in aquatic habitats than in terrestrial ones (Sculthorpe, 1967; Hutchinson, 1975; Grace, 1993; Duarte et al., 1994; Santamaria, 2002). The terrestrial ancestors of aquatic plants largely relied on sexual reproduction and during the evolution shifted from sexual to 135 asexual (vegetative) reproduction (Philbricic and Les, 1996). Nymphoides peltata is displajdng heterostyly with reciprocal positioning of sex organs in its morphs. The species is distylous witnessing reciprocal herkogamy as also reported by earlier workers (Ganders, 1979; Barrett, 1992). The syndrome of heterostyly is equipped with a strong incompatibility barrier which usually characterizes heterostyly complex. The results of present study reveal that self and intra morph pollinations failed to bring out fertilization and seed production while as only intermorph pollinations resulted in seed production (Figure 6.9). Our results negate the earlier report of Omduff (1966) who envisages a weak incompatibility system in the species but correspond to that of Wang et al. (2005). In heterostylous taxa with incompatibility complex the two mating morphs are obligatory for normal sexual reproduction. In such cases physiology determines mating patterns meaning that thrum can mate only with pin and vice versa. This negative frequency selection maintains the floral polymorphism and leads to isoplethic morph ratio (Fisher, 1941; Charlesworth, 1979; Heuch, 1979; Barrett, 1993). The conservative index associated with heteromorphic incompatibility is isoplethy meaning that populations contain 1:1 ratio of individual morphs. However, A^. peltata resorts to profuse vegetative proliferation (Van der Velde and Van der Heijden, 1981) which yields heterogeneous values of morph frequency (Orunduff, 1966; Marui and Waishitani, 1993).The clonal growth of the species results in biased morph ratios and wide monomorphic patches. The clonality thus interferes with the normal sexual reproduction which is mate and morph dependent. The results of the present study correspond to this especially in Wular lake which has many monomorphic populations and is believed to be the result of clonal propagation. The dimorphic populations of N. peltata in Wular Lake exhibited extreme spatial segregation of the floral morphs than other lakes as a result of prolific clonal growth. So it appears clonal reproduction is the main survival strategy of N. peltata in the lake. In incompatible heterostylous taxa maximum fruit and seed set is achieved when the two morphs are mate saturated indicating that the morphs are at isoplethy-1:1 ratio (Wang et al., 2005; Brys et al., 2007). Nymphoides peltata being distylous with strong incompatibility also displayed the same trend. Maximum fruit and seed set were achieved when the morphs were at 1:1 ratio with nonnal random spatial dispersion of their individuals. Fruit and seed set declined with biased morph ratios as common 136 morph failed in expected level of fertilization. Clonal monomorphic populations fail to set seeds as they experience mate deficiency. The reproduction in the species is thus negatively frequency dependent. Declining the ratio to 1:0, the monomorphic populations resulted in failure to set seed. The stress of mate deficiency with clonality interfering with normal sexual reproduction has influenced the complex syndrome of heterostyly (Brys et al., 2007). The heterostyly syndrome struggles with fertility selection. The latter is known to favor seed formation. During the present study reciprocal crosses between mating morphs yielded different values of seed set. Pin morjDh individuals produced almost double the number of seeds than thrum morphs (while serving as female parent). The pin morph serves as a potential female parent and thrum morph as potential male pollen producing parent. This is an initial event of gender specialization which in due course of time may lead to dioecy as interpreted by Ornduff (1966). In several genera of angiosperms, distyly has evolved into dioecy (Baker, 1958) and in every case individuals bearing female flowers are evolutionary derived from long styled (pin) individuals, while male plants are derived from short styled (thrum) plants. Our results are a direct reflection of the above fact. If Nymphoides peltata is preparing to shift to dioecy from distyly, the incipient gender specializations certainly marks the beginning. Nymphoides peltata - is a very widespread invasive macrophyte in Kashmir and has invaded all the lakes and wetlands in the region (Khuroo et al., 2007; Reshi et al., 2008). In Wular lake there is a rapid increase in water levels from February to March and leaves of A^. peltata start to appear on water surface by early April. Leaves growing in shallow water tend to be smaller than those growing in deeper water (Vander Velde et al., 1979). By the middle of May, locals start harvesting the plant for fodder (Figure 6.6) and the cycle continues for more than three months. Because N. peltata has a high biomass productivity and a high leaf-turnover rate (Brock et al., 1983; Tsuchiya et al, 1990; Marion and Paillisson, 2002), the regrowth of the leaves at the sites where harvesting has been done earlier, takes only 30-40 days. By the end of august, the growth of the plant slows considerably, however, continues for several more mionths. A similar growth pattern ofN. peltata has been observed in other lakes and wetlands in Kashmir as well (Qadri and Yousuf, 2005; Kumar and Pandit, 2006). The results reveal that there is strong intra morph and self incompatibility in N. 137 peltata. The populations of N. peltata in Wular lake are characterized by extreme spatial segregation of the floral morphs than other lakes. So it appears that the high density of A^. peltata stands result because of clonal growth. In fact in Wular lake we see the greatest number of short discreate rhizomes than other lakes. Besides the other reason that appears to be relevant is the excessive harvesting of the plant during the summer season, accompanied by a decline in water levels, favoring clonal growth as the prominent mode of reproduction in A^. peltata in Wular lake. 6.5 CONCLUSION Our results reveal that clonal propagation appears to be the main reproductive strategy of Nymphoides peltata in Wular lake. The higher seed production in pin morphs suggests that N. peltata might shift to dioecy and suggest that this phenomena should be studied more keenly in future. 138 -'-___jr"^ '^-c— - . - ' -i^ .^^ M^ r*r - -;i-.-^:x- Figure 6.1: Nymphoides peltata along the eastern side of Wular lake in June Figure 6.2: Same location of Wular Lake in December. A^. peltata overwinters by forming short overwintering rhizomes which get buried under this sediment 139 U'^i Figure 6.3: Quadrats of standard size were used to count the number of short overwintering rhizomes in the sediment 11 <^ Figure 6.4: Collection of hibernating short overwintering rhizomes along with the sediment from Wular lake, for plantation in ponds for in vitro pollination experiments. 140 •rm^^\' Figure 6.5: A short hibernating rhizome anchored in the sediment by roots resumes growth and produces new leaves in the following spring at the same site. II I Figure 6.6: A^. peltata is harvested in large quantities by the locals for use as fodder 141 Bandipora Kehnusa 3 0 3 m Nympholdes peltata I I Wular Lake Kilometers Figure 6.7: Distribution map of Nymphoidespellata in Wular lake 142 n •I 6 I '^% • 1*4 • ' ; 9 / I i 12- 10^ 2 , - .. -13 ^ 11 Manasbal Lake \^larLake 25 ^ • • 15 \ 2,241 \ 020 .16 W • Nigeen Lake ZP^ ^ Oal Lake Thrum morph —A— pjn morph Figure 6.8: Location and floral morph proportions of the Nymphoides peltata populations surveyed during the present study in different lakes of Kashmir 143 Table 6.1: Results of floral morph proportions of the Nymphoides peltata populations studied in various lakes of Kashmir Floral morph proportion Population Latitude Longitude Sample size Pin Morph Thrum Morph WLl 34°18'12.64"N 74°33'9.45"E 350 50.86 49.14 WL2 34°20'5.33"N 74°33'48.28"E 229 85.98 14.02 WL3 34°21'15.95"N 74°31'47.79"E 105 50.48 49.52 WL4 34°23'17.04"N 74°31'59.04"E 175 91.43 8.57 WL5 34°24'19.87"N 74°33'10.72"E 27 0 100.00 WL6 34°23'15.37"N 74°39'39.23"E 94 17.02 82.98 WL7 34°22'12.67"N 74°39'22.73"E 34 0 100.00 WL8 34°24'9.42"N 74°34'27.81"E 105 100.00 0 WL9 34°18'59.90"N 74°31'33.23"E 95 73.68 26.32 WLIO 34°17'43.27"N 74°31'54.52"E 39 0 100.00 ML 11 34°15'19.25"N 74°40'55.14"E 107 48.91 51.09 ML 12 34°15'1.68"N 74°41'2.65"E 158 50.63 49.37 ML 13 34°15'2.40"N 74°39'20.76"E 15 73.33 26.67 DL14 34°7'18.15"N 74°52'29.85"E 25 100.00 0.00 DL 15 34° 6'49.50"N 74°52'11.95"E 38 51.45 48.55 DL16 34° 5'44.04"N 74°52'5.32"E 100 45.00 55.00 DL17 34° 5'2.07"N 74°51'22.57"E 21 100.00 0 DL18 34° 7'48.72"N 74°52'12.48"E 111 51.35 48.65 DL19 34° 7'34.34"N 74°51'26.94"E 19 0 100.00 DL20 34° 8'3.90"N 74°50'37.29"E 44 68.18 31.81 NL21 34°07'37"N 74° 49' 36"E 53 69.81 30.19 NL22 34° 06' 50"N 74°50' 08"E 95 49.47 50.53 NL23 34° 06' 42"N 74049. 59"E 21 71.42 28.58 NL24 34°06'31"N 74049' 40"E 22 100.00 0 NL25 34° 06' 49"N 74° 49' 32"E 19 100.00 0 144 60 n c 50 E cr < 40- 01 3 30 - a 'ilDall Lake Manasbail Lak e Nigeen Lake Wular Lake Figure 6.9: Variations in tiie number of short overwintering rhizomes produced in the selected lakes in Kashmir (mean ± SD). 80 - 70 - 60 S 40 I 30 20 10 n - Intermorph Intramorph Self Pollination Pollination type Figure 6.10: Fruit set following controlled intermorph, intramorph and self pollinations in N. peltata. The mean and SD are from the pooled data of 6 populations used in the experiment. 145 100 E o 40 * E 25 50 75 100 Frequency of Pin morph (%) 100 ^ li« 20 25 r 50.„. .75 , 100 Frequency of Pin morph (%) Figure 6.11: The influence of floral morph ratios (frequency of the L morph) on mean per cent fruit set (±SD) in the experimental population of Nymphoides peltata (a) total fruit set of flowerso f the pin morph type; (b) total fruit set of flowers of the thrum morph type. 146 60 - 50 - a ^ 40 - £ i 30 - b 01 10 n Pin female X Thrum male Pin male X Thrum female Figure 6.12: The results of the reciprocal cross wherein the pin morph when it acted as a female produced almost double number of seeds than when thrum morph acted as a female. 147 The valley of Kashmir has numerous natural lakes and wetlands, rich in biodiversity. The present work was carried in Wular Lake, the largest freshwater lake in India and a Ramsar site. During the past several decades, there has been continuous introduction of non-native species into the region and have invaded all the lakes and wetlands in the region. The present study was conducted on four invasive macrophjles viz., Trapa natans (Linn.), (Lythraceae), Nymphoides peltata (S.G. Gmel.) (Menyanthaceae), Alternanthera philoxeroides (Mart.) Griseb, (Amaranthaceae) and AzoUa cristata Kaulf. in Wular Lake. While T. natans and N. peltata are widespread in distribution and form abundant populations in the region, Azolla cristata and A. philoxeroides are recent introductions in this Himalayan valley. The selected species differ in their habit, so it was difficult to have a common approach for studying their ecology. Species specific parameters were studied in this thesis. The main focus of the present study was to analyze the temporal changes in the composition of macrophyte communities and environmental factors governing the distribution of selected invasive macrophytes. Sampling of water, sediment and macrophytes was done seasonally at the 6 selected sites identified in the lake. The first objective was to document the macrophyte composition of the lake. A total of 33 species of macrophytes distributed over 27 genera and 22 families were recorded in Wular Lake. Eight macrophytes collected in this survey including Bidens cernua L., Lycopus europaeus L, Veronica anagallis-aquatica L., Alternanthera philoxeroides (Mart.) Griseb, Echinochloa crusgalli Beauv., Potomogeton pectinatus L., Scirpus lacustris L. and Vallisneria spiralis L. were not previously reported from Wular Lake. Alternanthera philoxeroides (Mart.) Griseb. of the family Amaranthaceae is an invasive weed originally from South America and was reported first time from this Himalayan valley. Identification of AzoUa cristata was ascertained with the help of scanning electron microscopy. Pluriseptate gochidia with a distinct terminal anchor, granular megaspore perine surface and bicellular leaf trichomes are specific to AzoUa cristata. The thickness of the Azolla mats in Wular lake range between 5-10 cm and cause severe degradation of the ecosystem, besides direct economic loss to lake inhabitants who rely on this ecosystem for their livelihoods. 148 The second objective was to make an assessment of the abundance of the macrophytes in the lake. A floating (Im x Im) quadrat was used to record vegetation at the selected sites along many transects that best represented aquatic macrophyte composition. A total of 90 quadrats on each sampling occasion in spring, summer and autumn were laid and rated the abundance of plant species (rooted floating and emergents) present within the sample visually on a Domin-Krajina cover scale (1 = <20%; 2 = 21-40%; 3 = 41-60%; 4 = 61-80%; 5 = 81-100% of covering). For submerged species, a rake was used in these locations. The most frequent species recorded in Wular lake were Trapa nutans (66.67%), Azolla cristala (61.11%), Nymphoidespeltata (37.78%), Phragmites australis (28%), Ceratophyllum demersum (22%), Potomogeton lucens (20%) and Hydrocharis duhia. Among the selected invasive species, the abundance of Alternanthera philoxeroides had increased significantly from a mean value of 0.72 ±0.28 in 2008 to 4.50 ±0.71 in year 2011 (p<0.05). The mean abundance of Azolla cristata also increased significantly from 6.50 ±0.85 in 2008 to 8.28 ±0.96 in 2011. The mean abundance of Trapa natans has decreased from 18.66 ±1.42 in 2008 to 16.17 ±1.34 in 2011 (p<0.05). The abundance of Nymphoides peltata had also declined in year 2011, though statistically non significant (p<0.05). The results revealed that Alternanthera philoxeroides invasion was having a selective impact on different life forms of macrophytes. There was a decrease in the overall diversity of macrophytes with a significant decrease in the diversity of free floating macrophytes. Water depth ranged from a minimum of 0.2m to a maximum of 4.4 m. The overall mean depth of the lake in 2008 was 2.10 m and in 2011 the average depth was 1.97m. Water transparency ranged from 0.2-2.4 m in the lake. Dissolved oxygen is a fundamental variable in lake ecology and is a key control of both habitat quality and nutrient cycling. Dissolved oxygen is critical for the survival of all organisms in a lake besides controls important chemical reactions in the bottom sediment of the lake. Turbulence and water currents circulate dissolved oxygen throughout the water body, hence little variability was recorded among the selected sites, except S2 where it was significantly lower compared to other sites. On the seasonal basis higher values were recorded in winter and lowest in summer, 149 exhibiting tiie expected physical property of decreased gas solubility with increasing temperature. The concentration of calcium was much higher than that of magnesium and ranged from 17 mg/L at S2 in summer 2008 to 71 mg/L at S3 in winter 2011. Magnesium concentration ranged from 5.5mg/L at S6 in summer 2008 to 36.5mg/L at S4 in winter 2008. Magnesium and potassium also varied seasonally with decrease in their concentration during summer months corresponding to the peak growth of macrophytes, besides reduced surface runoff owing to decrease in rainfall in summer. Compared to other lakes, potassium concentration was higher in Wular Lake due to leaching from the agricultural and horticulture fields in the immediate vicinity wherein large quantities of fertilizers are used. No definite trend was observed for sodium as it fluctuated irregularly both in time and space in the lake. The cationic content of the waters revealed predominance of mineral ions in the order of Ca>Mg>Na>K as is known for freshwater lakes of Kashmir. The conductivity ranged from 170 ^SCm'' at site SI to 452 |iSCm"'at site S3 with an overall mean of 278.08 ^SCm''. The seasonal fluctuation of conductivity is mostly relate with the biological activity as the low value during summer months is due to uptake of ions by autotrophs during their growing season along with precipitation of calcium carbonate which is the main contributor to conducfivity. The textural and geochemical studies of Wular lake sediments have revealed that physical weathering dominated over chemical weathering, resulting in enhanced rates of erosion and consequent deposition of huge detritus into the lake. The chemistry of lake water and sediment is the indicator of catchment geology, weathering and erosional processes as well as anthropogenic activities. The granulometric characteristics resuks revealed silt and clay to be the major constituents of the lake sediments. The overall soil type of the lake can thus be classified as 'silt- loam'. The results of canonical correspondence analysis revealed that the abundance and distribution of Alternanthera philoxemides and Azolla cristata was not governed by any single factor or factors, rather they use the resources differentially to increase their abundance. The thickness of the Azolla mats in Wular lake range between 5-10 cm during winter and cause severe degradation of the ecosystem, besides direct 150 economic loss to lake inhabitants who rely on this ecosystem for their livelihoods. Management of AzoUa in Kashmir is the greatest challenge for aquatic weed managers. Although several methods of control are available, the biology of the plant limits the viable options. Because the plant has spread extensively in Kashmir, mechanical removal (effective for small, isolated infestations) is impractical. Chemical control is least desirable because the water is directly used for drinking by humans, besides other purposes. Biocontrol using the frond-feeding weevil Stenopelmus rufinasus can be explored as a management option for Azolla in Kashmir.The results revealed that Alternanthem philoxeroides invasion was having a selective impact on different life forms of macrophytes. There was a decrease in the overall diversity of macrophytes with a significant decrease in the diversity of free floating macrophytes. Monitoring of Alternanthera philoxeroides for 4 years revealed that the total number of patches had increased from 6 in 2008 to 82 in 2011 with total area of all patches increasing from 41.3 m^ in 2008 to 831 m^ in 2011. It is a noxious invasive weed worldwide and proliferates rapidly by fragmentation. Disturbance caused by harvesting fruits of Trapa natans and Nymphoides peltata for fodder promote are identified as factors promoting its fragmentation. Based on this data we did predictive modeling using a variable growth rate equation, to estimate the spread rate of the weed assuming the entire lake area available for spread. The results of the modeling exercise suggest that this weed may potentially cover entire lake in 13-19 years from 2008. As an exercise to check the robustness of our mathematical model, the data from the first three years and data from the fourth year was kept as a test sample to check if it agreed with the model predictions. The results of this sensitivity analysis were in coherence with the previous model. There is an urgent need to initiate a 'Maintenance Control' program that would keep the weed at lowest possible levels. Currently, such a program could be accomplished via hand-destruction of the plants. If a maintenance control program is not initiated, the rapid expansion of alligator weed will most likely cause the need for a major chemical control program and the development of a biological control program. The growth and phenology of Trapa natans was ascertained in Wular lake. Geographic Information System (GIS) was used to map the distribution of the plant in 151 the lake. Sampling was done every 4 weeks from April 2009 to September 2009 using a (Imxlm) quadrat. T. natans rosettes start to appear on the water surface in early April and form dense mats by the end of May. Rosette diameter increased from April and stabilized in the month of July. The other characteristics of the plant including biomass, rosette number and number of leaves per rosette also increase by the time flowering starts. As soon as the flowering and fruit formation starts, allocation of resources changes from vegetative to reproductive structures. This is an effective strategy of T. natans to segregate vegetative growth and seed production in a season, hence minimizing the competition between these two activities. Sedimentation of the lake has resulted in shifting of the dense stands of the plant into the lake. N. peltata commonly known as yellow floating heart or fringed water lilly is a very widespread invasive macrophyte in Kashmir. The species is distylous showing pin and thrum morphs in its populations. 25 populations of N. peltata were investigated in Wular lake and other major lakes of Kashmir. Each population was analyzed for floral morph ratio by sampling flowering ramets randomly. The populations of N. peltata in Wular lake are characterized by extreme spatial segregation of the floral morphs. The results reveal that clonal propagation appears to be the main reproductive strategy of Nymp ho ides peltata in Wular Lake. Overall, weed management is identified as an essential and integral part of the sustainable management of Wular lake for the benefit of the economy, the environment, human health and amenity. There is an urgent need to establish early detection and rapid response system (ED&RR) for the lake and the region at large. The costs associated with ED&RR efforts are typically far less than those of long- term invasive species management programs. Early detection offers the only likelihood of finding infestations that are small enough to hope to eradicate. A coordinated public outreach effort should be a component of rapid response efforts. Public awareness is identified as an important factor in locating and managing infestations. Sensitization camps, especially for the fishermen registered with the department should be a priority in controlling the spread of this weed in the lake. 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