Aquatic Ecosystems

1. What is the difference between benthos, plankton, and nekton?

Benthos are aquatic organisms that live on the floor of the body of water. They include ones that fix themselves to one spot, such as sponges, ones that burrow into sand, like worms and clams, or ones that walk on the bottom, like crawfish. Nektons are larger, swimming organisms like fish and whale. Plankton are microscopic organisms that are poor swimmers. Planktons are divided into two types, phytoplankton and zooplankton.

2. What is the difference between phytoplankton and zooplankton?

Phytoplankton are free floating algae or cyanobacteria, they can also perform photosynthesis. They are important because they form the base of many aquatic food webs. Zooplanktons are not photosynthetic crustaceans, larvae, or protozoans. Zooplankton typically feed on phytoplankton.

3. Summarize the changes in the three major zones of a river (headwaters, middle reaches, and mouth).

Headwaters are the sources of the river; they are typically shallow, cool, highly oxygenated, and flows very fast. Almost all of the energy input in headwater comes from detritus. Middle reaches are usually wider, deeper, warmer, slow flowing, contains suspended particles(cloudy), and less oxygenated. The mouth is deep, wide, and turbid because of sediments. These sediment may deposit and form deltas.

4. What is the difference between the littoral, limnetic, and profundal zones of a lake?

Littoral zone: Shallow area of water along shore of lakes where light can reach the bottom. It has high productivity because of the abundance of vegetation.

Limnetic zone: Open waters after the littoral zone. The limnetic zone is defined by the maximum depth that sunlight can penetrate to have enough light for photosynthesis. It is mainly inhabited by plankton.

Profundal zone: Beneath limnetic zone in large lakes. Light does not penetrate to this zone. It is only present in deep lakes. Its nutrient rich and lacks oxygen.

5. Why...