Question

flathead lake is a standing - freshwater ecosystem in northwestern montana. the flathead lake biological station is located on the shore of this lake. this station was built in 1899 and is a laboratory used by scientists to study flathead lake and the land that surrounds it.
which statements describe the flathead lake ecosystem? select all that apply.
it has the same amount of oxygen near the surface as it does at the bottom.
it has more oxygen near the surface than at the bottom.
it has water that is low in salt.

Explanation:

• In a freshwater ecosystem like Flathead Lake (a standing - freshwater ecosystem), the water is low in salt.
• Near the surface of a lake, there is more oxygen due to contact with the air and photosynthesis by aquatic plants (if present near the surface). At the bottom, decomposition of organic matter (by bacteria etc.) consumes oxygen, so there is less oxygen at the bottom.

Answer:

• It has more oxygen near the surface than at the bottom.
• It has water that is low in salt.