Freshwater Lentic Ecosystems

1. Oligotrophic Lakes

1.1. Oligotrophic Lakes have a small supply of plant nutrients. Water in these lakes is typically crystal clear and cold. Generally, they have a low NPP. Few phytoplankton and fish live in these lakes. The intensity of the light is very low but able to deeply penetrate the water. Oligotrophic lakes have a high oxygen content.

2. Eutrophic Lakes

2.1. Eutrophic lakes have a large nutrient supply. The water is typically very shallow and murky. These lakes have a high turbidity and NPP.Many types of plants, algae, and fish (Largemouth bass, northern pike, perch, panfish) live in these lakes. They have a low to medium oxygen content.

3. Mesotrophic Lakes

3.1. Mesotrophic lakes have a medium supply of nutrients. They have clear water where many fish (Walleye, Perch, Smallmouth Bass, Muskellunge, Northern Pike) live. These lakes are stratified into two layers (warm top layer that has a high oxygen content, cold bottom layer that has a low oxygen content).

4. Swamps

4.1. Swamps are dominated by trees, shrubs, and woody vines. They are the home to many fish, birds, amphibians, and mammals. They typically have poor drainage and a low oxygen content.

5. Marshes

5.1. Marshes are dominated by herbaceous species (grasses, rushes, seeds). They have a low oxygen content and a high production rate.

6. Lakes are made up of four zones: the littoral zone, the limnetic zone zone, the benthic zone, and the profundal zone.

6.1. The littoral zone is near the shore. It consists of shallow sunlit waters to the depth at which rooted plants stop growing.

6.2. The limnetic zone is an open sunlit surface layer away from the shore that extends to the depth penetrated by sunlight.

6.3. The profundal zone is a layer of deep ocean water where it is too dark for photosynthesis to occur. It has low oxygen levels with cool and dark water.

6.4. The benthic zone consists mostly of decomposers, detritus feeders, and benthos.

7. Lentic ecosystems can be formed by glaciers, volcanoes, and shifting of tectonic plates. There are some that are man-made. Some, such as vernal pools, are seasonal (only occur during rainy season). These ecosystems are stratified, each layer is able to support different organisms. The organisms that an ecosystem is able to support depends on factors such as the amount of light and temperature. Algae and aquatic plants produce food for other organisms in the ecosystem. Lentic ecosystems are home to many zooplankyton. They feed on algae and plants and provide food for other organisms such as snails and insects like water striders. The kinds of fish and other vertebrates depends on many factors, such as the salt content, amount of light, and depth of the water. There are many species of lentic vertebrates, including salamanders, frogs, alligators, and many kinds of birds.

8. Standing water

9. Only last from a few hundred to a few thousand years

10. Lower oxygen content (especially low in deeper zones)

11. Salt content rises as it evaporates

12. Animals help to stabilize water in bodies

13. Biotic Factors

13.1. Zooplankyton

13.2. Frogs

13.3. Algae

13.4. Insects

14. Abiotic Factors

14.1. Low salt content

14.2. Low oxygen content