Lake Ecosystem - Environment Notes

A lake is a body of standing water that is generally large enough in area and depth, regardless of its hydrology, ecology, or other qualities. The size of lakes varies considerably. The depth of lakes also varies significantly. Lake Baikal in Russia is the world's deepest lake. Nitrogen and phosphorus are the most important nutrients in the lake. These agents promote the growth of nutrient-rich plants and algae. These plants and algae provide food for other creatures, resulting in a complex and healthy environment. This article will explain you about Lake Ecology which will be helpful in preparing the Environment syllabus for the UPSC Civil services examination.

Lake Ecosystem - Light

• The solar energy required to fuel photosynthesis, the primary energy source of lentic systems, is provided by light.
• The amount of light received is determined by a number of factors.
• Small ponds may be shaded by trees nearby, and cloud cover can impair light availability in any system, regardless of size.
• Light availability is also affected by seasonal and diurnal factors, as the shallower the angle at which light strikes water, the more light is lost due to reflection.
• Lakes are split into photic and aphotic zones, with the former receiving sunlight and the latter lying below the depths of light penetration, devoid of photosynthetic capacity.

Lake Ecosystem - Temperature

• Because most life forms in lentic environments are poikilothermic, meaning their internal body temperatures are determined by their surroundings, temperature is an essential abiotic component.
• Radiation at the surface and conduction to or from the air and surrounding substrate can heat or cool water.
• A constant temperature gradient from warmer waters at the surface to cooler waters at the bottom is common in shallow ponds.
• Furthermore, diurnal and seasonal temperature changes can be significant in these systems.
• Large lakes have significantly varied temperature regimes.
• The frozen layer that forms on the lake's surface breaks up in temperate regions, leaving the water at around 4 degrees Celsius. The density of water is greatest at this temperature.
• Warmer air temperatures heat the surface waters as the season continues, making them less dense.
• Due to limited light penetration, the deeper waters remain chilly and dense.
• As summer approaches, two distinct layers emerge, separated by such a great temperature difference that they remain stratified.
• Inverse stratification happens in the winter when water near the surface cools and freezes, while warmer, denser water remains at the bottom. A thermocline is formed, and the cycle begins again.

Lake Ecosystem - Wildlife

• Mosses, ferns, reeds, rushes, and cattails are some of the plants that thrive along the shoreline.
• Floating plants like water lilies and water hyacinths thrive further from the coast. They have bladders or sacs filled with air that help them stay afloat.
• Small fish dart in and out of the holes in the leaves of these plants. Waterbugs, beetles, and spiders glide and scurry across or just beneath the surface.
• Turtles can warm themselves in the sun on small islands, floating vegetation, or fallen logs.
• Snails, shrimp, crayfish, worms, frogs, and dragonflies are among the small animals that live among the plants and deposit their eggs on them both above and below the waterline.
• Many different species of water birds nest and rear their young in lakes. The most prevalent lake birds are ducks.
• Swans, geese, loons, kingfishers, herons, and bald eagles are among the others.

Aging of Lakes

• Water bodies, like all living things, age with time. This ageing process is referred to as "eutrophication" in lakes.
• Lakes are formed as a result of diverse geological and geomorphic events, and they 'grow' over time to change their morphological and functional properties before eventually falling.
• Lakes derive their water from surface runoff (and sometimes groundwater discharge), as well as various chemical compounds and mineral matter eroded from the earth.
• Ageing occurs over millennia as the lakes gather mineral and organic debris and gradually fill up.

*For detailed notes on this topic, check this link Ageing of Lakes

Characteristics of Oligotrophic and Eutrophic Lakes

Oligotrophic Lakes

Young lakes are referred to as oligotrophic lakes. They have the following characteristics:

• Shorelines that slope down to the water's edge.
• Along the shore, there are mostly conifer trees (pine).
• They are deep and abruptly drop off.
• The majority of the bottom is rocky.
• The water is exceptionally clear.
• There aren't many aquatic weeds there.
• They have a high proportion of oxygen.
• Cold-water fish such as trout, steelhead, whitefish, and salmon inhabit them.
• Lake Superior in North America is an example of an oligotrophic lake.
• The shorelines of oligotrophic lakes erode and become less steep over thousands of years.
• More plant life arises on the coast and in the water as the rocks on the lake's bottom grind against each other, forming sand.

*For detailed notes on this topic, check this link Characteristics of Oligotrophic and Eutrophic Lakes

Eutrophic Lakes

Old lakes are referred to as eutrophic lakes. They have the following characteristics:

• Shorelines are typically flat and gentle.
• Along the coast, there are mostly deciduous trees and a lot of shoreline flora.
• When compared to lakes with a sandy or rocky bottom, they are usually fairly shallow.
• In waters deeper than 30 feet, there is very little oxygen.
• Organic matter and single-celled planktonic algae have coloured the water, making it murky.
• There is heavy weed growth in the water.
• There are few, if any, cold-water fish. In old lakes, however, bass, panfish, pike, and carp thrive.
• The inland lakes are the best examples of eutrophic lakes.
• All lakes have a natural tendency to fill up and become land.

*For detailed notes on this topic, check this link Characteristics of Oligotrophic and Eutrophic Lakes

Removal of Nutrients From a lake

The following methods are employed in a lake to remove the nutrients.

• Using nutrient-depleted water as a flush.
• Deepwater abstraction.
• P-elimination on-site using flocculation/flotation with water backflow or floating Plant NESSIE with adsorbents.
• Filters and P-adsorbers for on-site algae removal.
• On-site algae skimming and separator thickening.
• Destratification (permanent or intermittent) / artificial mixing.
• Fish and macrophyte harvesting.
• Sludge removal.

*For detailed notes on this topic, check this link Removal of Nutrients From a Lake

Ameenpur Lake - First Biodiversity Heritage Site

• Ameenpur is a small lake in the Sangareddy District of Telangana, India, on the outskirts of the city of Hyderabad.
• Because of the vast number of migrating birds that thrive there, the Ministry of Environment designated Ameenpur as a Biodiversity Heritage Site in November 2016 under the Biological Diversity Act 2002.
• It is the first body of water in India to be designated as a Biodiversity Heritage Site, as well as the first biodiversity site to be approved in an urban area.
• In 2017, the lake was home to eight mammal species, 166 birds, 45 herpetofauna (12 amphibians and 34 reptiles), nine fish species, and 143 invertebrates (26 aquatic beetles, 41 butterflies, 18 odonates, 25 arachnids, and 33 other invertebrates).
• Flamingoes are the most common birds found here.
• The Oriental Darter, Pallid Harrier, Black-tailed Godwit, Painted Stork, River Tern, and Black-headed Ibis are among the six species categorized as threatened on the IUCN Red List.

*For detailed notes on this topic, check this link Ameenpur Lake - First Biodiversity Heritage Site

Significance of Lakes

• Lakes are a crucial aspect of the water cycle because they collect all of the water in a certain area. The watershed, or all the streams and rivers that feed into a single lake, filters the water.
• Lakes have served as transportation and commercial channels for ages.
• Farmers irrigate their crops with lake water.
• Farmers benefit from the climate effect of particularly large lakes.
• Winds blowing from lakes help to make the climate more equal because water does not heat or cool as quickly as land. The "lake effect" is what it's called.
• Lakes sweep warmer air over the land in the autumn, extending the growing season and allowing farmers to continue growing their harvests.
• In the spring, cold lake breezes assist plants avoid over-growing and early-season frosts, which can damage young crops.
• Many settlements get their water from lakes. Drought-resistant water is stored in artificial lakes. Dam-created lakes also produce hydroelectric power.
• Lakes are popular recreation sites because they are quite attractive.
• Lakes are permanent homes for certain groups of people.

Conclusion

Lake ecosystems have been significantly impacted by a variety of anthropogenic disturbances, resulting in serious detrimental consequences on the structure and function of these ecosystems, despite their basic importance to humanity. The most serious of which include increased nutrient load, pollution, acid rain, and exotic species invasion.