ECOLOGY OF LAKES INTRODUCTION Lakes are standing water ecosystem and their ecology differs from those of running water ecosystems( river). Littoral zone near the shore with rooted plants and limnetic zone in plankton also develop in lakes dependent upon the depth to which sunlight can penetrate In lakes plankton shows a characteristic uneven distribution vertically Zooplankton are predominant over the phytoplankton. Crustaceans are the most important among the zooplankters Plankton of lakes comprises “ true plankton” produced locally in the standing water of the surface to depth sun light can penetrate and so differs from “ drift plankton” of the streams. It is characteristic of temperate lakes. This is particularly noticeable during summer and winter than during spring and fall when mixing occurs and the Thermal same temperature in the entire body of lakes. During summer and winter enormous temperate drop Stratification occurs from surface to bottom resulting in three thermal strata called epilimnion, thermocline and hypolimnion. Epilimnion is warmer than the hypolimnion which is the coldest ( often at 4 degree Celsius) Thermocline The thermocline is characterized by rapid fall in temperature as depth increases- a drop of more than 1 degree Celsius per metre of depth usually occurs. It becomes strong barrier between any vertical exchange of oxygen from epilimnion to hypolimnion and of nutrients from hypolimnion to epilimnion. The thermocline is an important consideration in fishery biology of the lakes. Knowledge of location of thermocline is very useful in angling sport fishing and survey sampling work Tropical lakes do not display thermal stratification and a thermocline does not occur in them owing to continual mixing of surfaces and deep waters which is either a gradual or irregular process. That is why tropical lakes do not display thermal stratification. Categorization Lakes are generalized Blue green alga, The oligotrophic lakes in two categories anabaena sp.,is a have lesser food depending upon their common plankter of available than productivity: oligo and lakes, particularly eutrophic ones have. eutrophic. eutrophic. Absence of turbulence Turbidity in lakes is and current helps in therefore generally setting of suspended very low and water is solids at the bottom of relatively clearer than the lake. in rivers. This Photo by Unknown Author is licensed under CC BY-NC-ND.