Question

grain size has to do with the size of the particles of sediment present. what are the sediments like in older beaver dams, and how does that impact cutthroat trout?

Explanation:

Older beaver dams have finer - grained sediments (smaller particles). This can reduce the amount of oxygen in the water (as fine sediments can compact and reduce water - flow - mediated oxygen exchange). Cutthroat trout need well - oxygenated water for respiration. Reduced oxygen levels due to fine sediments in older beaver dams can stress or even kill cutthroat trout.

Answer:

Older beaver dams have finer - grained sediments. This can lead to reduced oxygen levels in the water, which can negatively impact cutthroat trout (e.g., stress or death due to lack of sufficient oxygen for respiration).