BULL. BOT. SURV. INDIA Val. 24, N~or. 1-4 : pp. 70-75, 1982 AN ECOLOGICAL STUDY OF THE VEGETATION OF THE KOLLERU LAKE AND P. VENU AndAra University, Waltair ABSTRACT Kolleru lake is a large fresh water body extending over 850 sq. km in the Krishna and West Godavari districts of Andhra Pradesh, between 81'40' and 80'20' E and 17'25' and 1.6'28' N. The entire lake being shallow, has only littoral vegetation with practically no llrnnetic and profoundal zones. As the lake receives rich nutrients as effluents from the several drains that empty into it, the vegetation is luxuriant. About nineteen species of hydrophytes belonging to thirteen angiosperm families are recorded. Data on the distribution of these hydrophytes in the lake and their frequency, relative frequency and abundance from diffe- rent regions of the lake at different periods of the year, are presented. INTRODUCTION may be mentioned Biswas and Calder (1937)~ Fresh water macrophytes play a very im- Misra (1946), Mirashi (1954, 57, 58), Mahes- portant role in aquatic ecosystems. They pro- wari (1960), Chavan and Sabnis (1961)and vide food and shelter for a number of organ- Unni (1967). There appears to be no pub- isms including some economically important lished work on the vegetation of Kolleru fish while an excessive growth of these plants Lake except for the passing remarks in may interfere with man's use of fresh water Subramanyam's Aquatic Angiosperms. by obstructing water flow, navigation and Data obtained from the study of the eco- fish production and may sometimes create logy and weed biology of Kolleru lake dur- problems for sanitaiton. The importance of ing the survey of the lake from June 1977 fresh water macrophytes in the biological to February 1978 are presented. by productivity has earlier been emphasized THE AREA OF STUDY (1933) Butcher and Welch (1935) The Inter- Kolleru is a large fresh water lake in national Biological Programme has given an Andhra Pradesh situated between the impetus for a global study of tIie primary Krishna river on the West and the Goda- productivity of the macrophytes. vari river on the East. The lake has an However, in India the systematic and eco- area of about 904 square kilometer at logical study of aquatic macrophytes as a + 10 contour level, of which 260 square kilo- group has not received the necessary atten- meter is in the Kaikaluru and Gudivada (I 962) tion. Subramanyam's Aquatic Angi- taluks of Krishna District and the rest in osperms is distinctive among the Indian Eluru, Bhimavaram and Tadepalligudem literature on the aquatic macrophytes. taluks of the West Godavari District. The Among other contributions on the subject area lies between longitudes 81" 40' and soe 20' in the East and latitudes 17" 25' and *Prs~mtaddress : A. N. R. College, Gudivida 28' Date of receipt : 15.4.80. Date of acceptance : 4. 1. 82. 16° to the Nonh. Geologically, it is be- lieved to be of recent origin formed by ex- weight of the species that occurred in that cessive silting of the Kr7shna and Godavari articular quadrat as it was not possible rivers, of an earlier lagoon separating it com- to count the individual number of species pletely from the sea. The lake receives an occurring in each quadrat. Sampling was inflow of more than ~oo,ooocusecs and its done along two transects selecting some field discharge to the sea by its only outlet the stations in each transect. Only one tran- 'UPPUTER~is much less. The lake is sect could be covered in a day. The field connected to the sea which is 32 kilometer stations that were visited are marked in away by this narrow waterway. The lake the Map. The quantitative characters of the receives drainage from a catchment area of vegetation were analysed based on the over- about 5zm square kilometer of which three- all sampling of the vegetation in each of the fourths is from upland area and a quarter transects and the number of quadrats from the delta area. Thus the lake expands sampled in each rransect varied from 15 during the rainy season inundating the to 30. neighbouring areas while during summer, RESULTS AND DISCUSSION a rnzjor part of the lake gets dried up* The di7ferent aquatic macrophytes that About rg small canals or drains empty are encountered are summarised in Table I into the lake which has ~rolificgrowth of an'd their distribution in Table 2. Informa- several aquatic weeds. The important ation on frequency, relative frequency, streams and canals that join Kolleru lake density, relative density of all macrophytes are I. Tammileru, z. Ramileru, 3. Buda- of the lake, representing the average value meru, 4. L. S. drain of Neharalli channel, for the entire lake, based on data from 117 5. Rallacodu, 6. Chandraiah drain, 7. L- quadrats studied during the entire period of Moturu channeI, 8. Polraj drain, 9. Pe- of the survey from all the field stations has 7. dapadu drain, 1 o. Vatluru drain, I I. Man- been summarised in Table Among the different mscriphytes in the dicodu drain, 12. Kovvali drain, 13. Takka- lapalli drain, 14. Pandicodu drain and 15. lake, OtteZia alismoides (L.) Pers. showed Siddapurarn drain (Map). maximum percentage frequency and rela- METHODS OF STUDY tive frequency followed by Ipomoeo aquu- The vegetation of the lake mainly consists tica Forsk. and Nymphoides indicum o of emergent, submerged and free floating 0.Kuntze. In spite of the fact that Eich- forms of intermingled mats. Thus quami- homia crassipes (Mart.) Solms. occurred in tative sampling of vegetation of the lake greater abundance in localities such as posed a very serious problem both for ap- Pedayedlagadi etc., the frequency, and rela- proach to the area and for sampling. Dif- tive frequency of this species is much ferent types of macrophyte samplers have lower and it occupied the 6th place in the been designed, fabricated and tested dur- order of importance. Blyxa octandra, ing this period. Of the various samplers (Roxb.) Planch. ex Thw., Vallisneria spiralk tested, a rotatory similar to one L. and Phragmites karka (Retz.) Trin. ex described by Howard-Williams and Long- Steud. are highly restricted in their distri- man Gg76) has been used with good results. bution king present only in Deyyampadu, Each collection was washed and sorted out KomatiIanka and Kolletikota respectively. It is interesting to note that the two corn- for the different species and their fresh - weight was determined after removing ex- man species Ceratophyllurn demersum L., cessive adherent water. Quantitative Hydrilla verticilluta Royle are conspicuous. mations were made on the. basis of fresh ly absent in. the lake. The lake being very 72 BULLETIN OF THE BOTANICAL SURVEY OF INDIA vo1. 24 Map of Kolleru lake showing various field stations. 1. Atapaka. 2. Kornatilanka. 3. Nattagullapadu. 4. Singapuram. 5. Chataka. 6. Urumullanka. 7. Kolletikota, 8. Kaikaluru. 9. Chintapadu. 10. Deyyampadu. 11. Pedayedlagadi. shallow, there is no dear cut zonation of stands of submerged species in lake Osbysjon emergent, submerged and free floating spe- while Swindale & Curtis (1957) reported in cies, all occurring in intermixed mats, Wisconsin lakes, the submerged vegetation though in some areas Ottelia alismoides 6.) as of heterogeneous composition. However, Pen. occurred in continuous patches. Fors- Unni (1971)repORS both heterogeneous and berg (1960) observed the such monospecific monospecific stands of aquatic vegetation in 1c$2] SESHA~ATHARAMet al. : AN ECOLOGICAL STUDY OF THE VEGETATION OF KOLLERU LAKE 73 TABLE 1 LIST OF MACROPHYTES OCCURRING IN KOLLERU LAKE -___----------- --- --I_-, - Sheties Family --____ - - -ud+--/----L --_ - 1. HYDROPHYTES ATTACHED TO SUBSTRATUM (a) Emergent hydraphytes : 1. Phragmites karka (Retz.) Trin. ex Steud. Poackae 2. Typha angustata Bory & Chaub. Typhaceae 3. Scirpus articulatus L. Cyperaceae 4. Pusjalidium geminaturn (Forsk.) Stapf Poaceae (b) Floating leaved hydrophytes : 5. Aponogeton crispurn Thunb. Aponogetonaceae Nymphaceae 6. Nymphaea nouchali Burm. fa 7. Ny8,zphoides indicum (L.) 0. K31ntze Gentianaceae 8. Ipomoea aquaticn Forsk. Convolvulaceae 9. Alternnnthera sessilis L. Amaranthaceae (c) Submerged hydrophytes : 10. ~allGnneria spiralis L. Hydrocharitaceae 1 I. Bbxa octnndra (Roxb.) Planch. ex Thw. Hydrocharitaceae 12. Ottelia alismoides (L.) Pers. Bydrochari tacme 13. Limnophila indicn (L.) Drw Scrophulariaceae 14. Nechamnndra alternifodia (Roxb.) Thw. Hydrocharitaceae 11. FREE FLOATING FORMS : 15. Saloinia auriclclata Aublet Saiviniaceae 16. Eichhornia crtlssipes (Mart.) Solm9. Pontederiaceae 17. Utricularia stellaris 14. f- Lentibulariaceae 18. U. fhttosa Vahl Lentibulariaceae --- 19. ~isiiastratiotes La Araceae TABLE 2 TABLE SHOWING THE DISTRIBUTION OF DIFFERENT AQUATIC MACROPHYTES OF THE LAKE N~~.1 to 11 represent the field stations.. See legend of Map for details ). Phragmites karka 3~fihaangustata Scirfius articula tus POrjnlidium getnitraturn APonogefon crirplttn Jf~,qzphaeanouchali Nymphoides indicur~t Ifiomoea aqzlnlica Alternnntheh sessilir V~llisneriashirnlis Bbxfl octandra 74 BULLETIN OF WEBOTANICAL SURVEY OF INDIA pol. 24 Species Ottelia al*&s +++++++++++ Lima#& in& + - ++++- - +- NkhamarrALu altemifolia ++++- - - +-- Salvinio a&&ta - ++++- - - + + - Ekhhmia crarripss + - - - - - - - - - + Utn'cuhria spp. ++-I-+++-- - - - Pirria shatiotc; +++++- - - - - - -4- I--C--C-C--. C--CC---c. FREQUENCY, RELATIVE FREQUENCY, DENSITY AND RELATIVE DENSITY OF DIFFERENT AQUATIC MACROPHYTES OF KOLLERU LAKE Total No. of Total wt. Percentage Relative Density Relative Name the species No. of quadrats of the frequency frequency (gm-2) density quadrats of accur- species studied rence (gm- '1 -- Otrdi4 alismoidrs 117 63 44035 376.36 35.48 ripamam aguatim 117 58 42 180 360.50 33.90 Ny&&s indid111 117 24 10105 86.36 8.14 Aponogdton dm 117 10 1475 12.60 1.18 Nctkmandm ahmifofid 117 13 4055 34.65 3.20 &&~nhCIOSS@~ 117 7 2220 18.97 1.78 Zkri- indicu 117 7 1160 9.91 0.93 Utn'cularia spp 117 8 830 7.09 0.66 Rfisrmmtlbra sasilis 117 4 2620 22.30 2.1 1 *!* dl?guukt@ 117 5 610 5.20 0.40 ValIGnrria spirafis 117 2 435 3.70 0.35 Btyxu ociandra 117 2 2 70 2.30 0.21 Phmgmitas karka 117 2 630 5.30 0.50 Nqjtas rpp.