Macrophytes of Dal and Nigeen Lake and Succession After Invasion of Azolla
Total Page:16
File Type:pdf, Size:1020Kb
SSRG International Journal of Agriculture & Environmental Science ( SSRG – IJAES ) – Volume 4 Issue 3 May to June 2017 Macrophytes of Dal and Nigeen Lake and Succession After Invasion of Azolla 1Shahnawaz Ahmad (F.S.E.Sc), 2 NayaraTaban 1 Fellow society of Environmental Sciences, University of Dumka. Technical Asst, J&K Lakes and waterways development Authority, Srinagar, Kashmir. 2 Scientist-A, J&K Lakes and waterways development Authority, Srinagar, Kashmir. Abstract Macrophytes usually show a succession of zones Succession of macrophytes in the lake became between the dry land and water, each zone with a more dramatic and dynamic after invasion of Azola ie dominating plant species. 2004. Variation in the latter depends on the duration The weed pushes and smothers other free-floating of the flooding and may also be affected by ecological macrophytes like lemna sp. It then provides substrates succession - where a plant community alters for the emergent weeds, which later reduces its environmental conditions in a way that makes the population by competition for light and nutrients. habitat less favourable for its own survival but more favourable for the development of a different Keywords: Dal Lake, Macrophytes, zonation, community. The present study was carried out to succession determine the distribution, affect on nutrients and succession Patterns of macrophytes in Dal Lake after I. INTRODUCTION the invasion of Azolla. Macrophytes are higher plants that grow in ecosystems whose formation has been dominated by II. MATERIALS AND METHODS water and whose processes and characteristics are The Dal Lake has been divided in to four largely controlled by water. Factors that influence the Basins for the study purpose which include Nishat establishment of macrophytes include: depth, Basin,Hazratbal Basin,Nehrupark Basin and Nigeen topography, type of substrate, exposure to currents Basin. Monitoring and surveillance of and/or wind and water turbidity. The distribution of Macrophytes in the lake were done monthly using a macrophytes is often related to their mode of Boat with an outboard engine. Macrophyte species attachment (Sculthorpe, 1976). The distribution, occurring in the various sites were recorded and the permanency and quality of the water bodies available depths at which they occurred. Specimens were for their occupation govern the distribution and ecology collected for herbarium preparation and further of these plants. identification. To estimate the macrophyte population The most variable environmental factors of densities within the lake. Random quadrant method was basic Ecological importance for aquatic plants are the used. Length of the period during which water is present, whether the water is still or moving, the availability of III. RESULTS AND DISCUSSION plant nutrients and the quality and quantity of light A total of 20 families and 28 species common penetrating into the water. Macrophytes can be Macrophytes were recorded from the different sites in subdivided into four groups on the basis of their water the lake (Table 1). This was probably so because most requirements and habitats. of the back waters are covered with Radhs and land Submerged macrophytes are those that are masses were these weeds get suitable nutrients to grow. completely covered with water. These have leaves that Comparison of open water sites and peripheral areas of tend to be thin and finely divided adapted for exchange the lake, macrophytes show very much different of nutrients with water. Floating leafed macrophytes are distribution not only in terms of species and family but those that are rooted but have floating leaves while free also in their density as well. Stations within the floating are those that float periphery were dominated by cryspus (september to On the water surface. The last group is the March),hydrilla(April to August) and emergent macrophytes. These are rooted plants with cerotophylleum(through out the year) while those in the their principal photosynthetic surfaces projecting above open waters were dominated by lucens,nymphoids and the water. Emergent macrophytes dominate the natans. Sediment deposition from different input shoreline flora while the middle and lower littoral zones channels such as telbal, pishpaw, Botakul and supports stands of floating-leafed macrophytes. Meraksah has shown lot of effect on the Macrophytic ISSN: 2394-2568 www.internationaljournalssrg.org Page 34 SSRG International Journal of Agriculture & Environmental Science ( SSRG – IJAES ) – Volume 4 Issue 3 May to June 2017 pattern of the lake. And most importantly azolla weed restricts the light to penetrate in to the water thus which was under study in this particular studies shows slowing down the process of photosynthesis. Some its first existence through these channels, where from at common macrophytes recorded in Dal and Nigeen least 70% of the Azolla found in the lake come from Lake. (Dal lake booklet-Dr. Mrd Kundangar, these channels and 30% of this weed grows over the Dr.S.G.Sarvar-1997). lake surface, thus forming mat like structure and covering the water surface. Phragmites cummins Lamarck established the name Azolla in 1785 Typha Angustata (Svenson (1944) as cited by Quebral, 1989). It was Sparganium erectum derived from the Greek words azo (to dry) and ollyo (to Sagittaria sagitifolia kill) meaning, “When it dries it dies”. Rumex martimus Fossil record of Azolla Lam. dates back Azolla pinnata around 100 million years ago (Fowler (1975) as cited Ceratophyllaceae by Payawal, 1989) and seven extant Azolla species Ceratophyllum demersum (A.filiculoides, A. caroliniana, A. mexicana, A. pinnata, Rananuculus scleratus A. nilotica, A. microphylla,A. rubra) are reported Potentilla repans (Armstrong, 1998; Bergersen ed., 1980; College of Polygonum hydropiper Tropical Agriculture and Human Resources, 2000; Myosotis sylratica Croft, 1986; Darbyshire, [n.d.]; Kay and Hoyle, 2000; Menyanthes trifoliata Ladha and Watanabe 1987; Pacific Island Ecosystems Galium hertifolium at Risk, [n.d.]; Payawal, 1989; Singh, [n.d.]; University Epilobium hirsutum of Wisconsin, 1999; Watanabe, 2001). Alisma plantigina Azolla is commonly described as small, Equisetum diffusum floating aquatic fern, capable of Rapid vegetative Marsillia qudrifolia reproduction by fragmentation and forms a mat on still Najas graminia waters like rice paddies, canals or ponds (Lumpkin, Juncus sp. 1987). It is found both in the temperate and tropical Hydrocharis morus-ranae regions of the world (Armstrong, 1998; Examining any Hydrocharis dubia sample of Azolla under a microscope shows it to have Myrriophylleum verticillatum filaments of Anabaena living within ovoid cavities Myriophyleum spicatum inside the leaves (Arms trong, 1998; Bergersen ed., Nelumbo nucifra 1980; Brady and Weil, 1996; College of Tropical Nymphea alba Agriculture and Human Resources, 2000; Nymphoids peltatum The Azolla-Anabaena association can fix Trapa natans nitrogen proportional to its Biomass produced (National Trapa bispinosa Azolla Action Program, 1990). It can fix from 450 kg Potamogeton crispus N/ha/yr to as much as 600 kg N/ha/yr (Quebral, 1989). P. pectinatus With this the light penetration becomes very difficult P.lucens and in turn submerged weeds get less light and do not P.pucillus grow at their natural pace. These channels also bring Cerotophyleum demersum with them the slit from the catchment areas thus Utricularia flexuosa changing the bed of the lake which also in turn affect Salvinia the Macrophytic or weed pattern of the lake. The study Lemna minor was carried for one complete year starting from April- 2014 to March 2015.During the study along the During the study it was observed that the Macrophytic growth pattern the water qulity of the lake Azolla develops in two types of environment, one in the on the particular sites was also studied,which showed channels which are the source of water for the lake and variations in some of the physico-chemical properties have marshy type of habitat and when these channels and nutrients present in the water. The physico- are filled with water this developed Azolla comes into chemical properties which showed variation were pH, the lake with the flow of the water. Another one is the conductivity, Nitrate-Nitrogen and Ammonical- development of Azolla within the lake itself where the Nitrogen.The weeds which were affected by the already present spores of the weed (Azolla) develop on inclusion of Azolla were Lemna-sp.Salvinia- the peripheral areas of the lake which adds with the sp.Myriophylleum-sp.and all the submerged plants like incoming Azolla from the channels thus forming the Potomogetan Lucens,Hydrilla etc. as Azoola when mats on the surface of the lake which actually created spreads over the suface of the water covers it and the problems for the lakes flora and fauna. Azolla is a ISSN: 2394-2568 www.internationaljournalssrg.org Page 35 SSRG International Journal of Agriculture & Environmental Science ( SSRG – IJAES ) – Volume 4 Issue 3 May to June 2017 genus of small aquatic ferns with a world-wide level which confirms the relation between Azolla and distribution. The sporophyte consists of a pinnately Anabaena to absorb nitrogen from the atmosphere. branched floating stem. Simple roots, which hang down With the increase in nitrate nitrogen, Ammonical into the water, occur at some nodes. The branches and Nitrogen level showed decrease. stem are covered with small, alternate, overlapping leaves. S.No Parameters Units pre post 1. pH -- 8.1 7.1 2. Conductivity