Question

1. after a week with lots of rain, runoff has caused a large amount of fertilizer to wash into the ocean from the farms on the california coast. this caused a bloom in phytoplankton. when these microscopic creatures die after their short life, their decomposition creates an environment in the water with little oxygen, making it toxic to mussels and crabs. identify two organisms which will be affected (other than mussels and crabs), state if their population would increase or decrease, and describe why this increase or decrease would be observed.

Explanation:

1. Fish:

• Decrease: Fish need oxygen to survive. The low - oxygen environment (caused by phytoplankton decomposition) makes it difficult for fish to respire. As a result, fish may suffocate or be forced to leave the area, leading to a population decrease.

1. Seabirds:

• Decrease: Seabirds often feed on fish, mussels, and crabs. If the populations of their prey (such as fish, mussels, and crabs) are affected (mussels and crabs are already affected by the toxic, low - oxygen environment and fish may also be affected as explained above), the seabirds will have less food available. This lack of food resources will cause the seabird population to decrease.

Answer:

Organism	Increase or Decrease?	Why is this Observed?
Seabirds	Decrease	Prey (fish, mussels, crabs) population is affected, leading to less food.