Explanation:

Freshwater is defined as having a low salt concentration- usually less than 1%. Plants and animals in freshwater regions are adjusted to salt content and cannot survive in areas of high salt concentration (i.e. oceans).
Freshwater ecosystems can be divided into two categories:

• A lentic ecosystem entails a body of standing water, ranging from ditches, seeps, ponds, seasonal pools, basin marshes, swamp and lakes. Deeper waters, such as lakes, may have layers of ecosystems, influenced by light. Ponds, due to their having more light penetration, are able to support a diverse range of water plants. There are also known as Pond ecosystem.
• A lotic ecosystem can be any kind of moving water, such as a run, creek, brook, river, spring, channel or stream. The water in a lotic ecosystem, from source to mouth, must have atmospheric gases, turbidity, longitudinal temperature gradation and material dissolved in it.