Anthropological activities crucial to food production such as agriculture and the raising of animals have an impact on lakes. Describe which organisms may be affected there and how these abiotic features are tested by an ecologist.

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Anthropological, or human activities and actions, such as agriculture and animal husbandry, can have devastating impacts on lake ecosystems. Ecologists often measure abiotic features to provide information about the health of fresh water habitats. Abiotic (non-living) factors can be more easily and quickly determined than biotic (living) ones. For example, it is quicker and easier to measure oxygen levels in a water sample than it is to measure complex interactions between autotrophs, producers, consumers, and decomposers.

When farmers plant crops, they often use nitrate-rich fertilizers to increase the health of their harvests and the size of their yields. Nitrates from chemical fertilizers eventually make their way into rivers, lakes, and streams through rain runoff over impervious surfaces. Inorganic salts from fertilizer also dissolve into ground water, which seeps into nearby bodies of water. Likewise, animal husbandry produces lots of manure or animal feces. Animal excrement leaches into soil and make its way into lakes through the same processes. Manure can also be used as fertilizer, so commercial farms might utilize a mix of the two in their operations.

A healthy lake ecosystem is able to easily filter out moderate amounts of excess nitrates—a process known as denitrification­—but large amounts, or unusual isotopes of nitrogen, are harder to naturally neutralize. During denitrification, nitrate is converted by bacteria in the lake into nitrogen which is then released into the atmosphere. When nitrate cannot be converted back into nitrogen, nitrate levels increase, leading to eutrophication.

Eutrophication occurs when increased nitrates are absorbed by algae, causing populations to grow out of control (algal blooms). Blooms create thick layers of algae to build up and film over the top of a lake’s surface. This bloom blocks sunlight from reaching the plants below and saps the water of oxygen, effectively creating a dead zone where neither plants nor fish can live. The result is an accumulation of decay at the bottom of the lake, which further contributes to increasing levels of toxic nutrients in the water.

To examine the health of a lake, an ecologist would examine abiotic components first. Abiotic components like sunlight, temperature, salinity, nutrient levels, and altitude may all offer insights into biotic conditions. In particular, an ecologist would test a lake ecosystem near large farms for elevated nitrate levels to determine the interactions between the fish, plants, and algae living there. Studying nitrate levels would show whether denitrification was taking place or if nutrient levels were building up to dangerous levels. Ecologists might also examine oxygen levels and sunlight levels, as eutrophication causes algal blooms to deplete the ecosystem of both.

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Anthropological activities crucial to food production like agriculture and raising animals have significant impact on lakes. Propose a solution to the issue, and describe the effects they will have on the lake ecosystem.

Many problems related to agriculture, within the larger condition of Nonpoint Source Pollution (NPS), are caused by runoff. One effect is sedimentation, which contributes to reducing the amount of water flowing into lakes via streams and rivers. The ways to reduce sedimentation include changes in farm management practices. Farmers could work on practices such as controlling the runoff water’s volume and rate of flow and keeping soil in place. These will be especially beneficial by reducing changes in the shoreline or littoral zone that is home to numerous plant and animal species, including birds and amphibians.

Another NPS, agricultural runoff-related problem is chemical use, especially when applied as fertilizer, herbicide, or pesticide. The chemicals applied to the land enter streams, rivers, and lakes after it rains or snows. Regarding pesticides, the practice of Integrated Pest Management (IPM), a systematic approach tailored to the soils, climate, and crops, as well as the pests presenting a problem in a specific agricultural field. By encouraging natural barriers, IPM not only reduces pesticide use and related movement from field to water, but supports biodiversity. Reducing the chemical pollution in lakes promotes healthy development of native biota and reduces risks of harm to humans and other animals who consume the plants and animals that grow in and utilize the lakes.

Animal grazing is associated with the production of manure that enters the water. Adjustments to grazing intensity and restricting livestock from sensitive areas are likely to reduce the amount of manure entering the water. In turn, this will help encourage the naturally beneficial vegetation while preventing undesirable plants from growing, promote healthier fish habitat, and protect streambanks and floodplain areas.

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Anthropological activities crucial to food production that can have significant impact on lakes are agriculture and raising animals. Which organisms may be affected, and how are these abiotic features tested by an ecologist?

The term “lake” may be applied to bodies of water of many different sizes and configurations. Limnology is the science that studies lakes. One abiotic feature is the type of ecosystem in which the lake is located. Along with location, the size has a strong effect on the organisms that live in and around it. For example, Lake Titicaca, shared by Peru and Bolivia at about 3,800 meters (more than 12,000 feet) above sea level, has a unique ecosystem in part because of its very high-altitude location.

In all lakes, fluctuations in water level mean that the shoreline constantly changes, which affects the kinds and amounts of plants and animals that will thrive there as well as in the deeper part of the lake. The close interactions among all aspects of a given ecosystem, which may be described as an ecological pyramid, mean that changes to one abiotic feature are likely to impact every organism. The decayed organic material, or detritus, within lake systems is crucial, because of its role in sustaining life.

The world’s largest freshwater lake by volume is Russia’s Lake Baikal, which holds more than 23,000 cubic kilometers (about 5,670 cubic miles) of water; its far northern location means that it is frozen for at least one-third of the year. This clearly demonstrates the importance of another abiotic feature: temperature.

The abiotic features characteristic in a given ecosystem include wind and current. These effect temperature and the surface and subsurface movement of water. Light is another abiotic feature which is crucial to the biota, because plants need it for photosynthesis. This process is related to the abiotic feature of chemistry, including oxygen production. Changes may occur because nutrients, such as nitrogen and phosphorous from fertilizer, have been added; this process is called eutrophication. Other changes include salinization from erosion or runoff, which may affect the terrain of the lake, whether along the shore or at the lake’s bottom.

The tests that would determine how pollution, often from runoff resulting from farming and ranching activities, would vary according to specific factors. Some of the most commonly applied tests are for E. coli bacteria, total dissolved solids, pH, hardness, iron and manganese, aluminum, and sulfates. Temperature is tested with a thermometer. Specific meters or less-expensive kits can measure dissolved oxygen. A Secchi test for cloudiness, indicating sediment, is done by lowering the black-and-white Secchi disk into the water.

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