Levels of nitrogen and phosphorus are the key to excessive phytoplankton growth and decompostion, which depletes dissolved oxygen. Stored and released by bottom sediments, nutrients are used and reused. When sediments sink to the bottom, they change the character of the Bay's floor. Sediment deliveries to the Bay system are highly seasonal and unique to each tributary. While not an acute threat, toxicants are present in the tissue of the Bay's living resources.
Phytoplankton are the first link in the food web, but an overabundance causes imbalances.
Zooplankton are usually the prime consumers of phytoplankton and are often critical food for larval, juvenile, and some adult fishes. Harvests of marine-spawning fish, which depend on the ocean rather thatn the Bay, are relatively good. Shellfish harvests remain at all-time lows due to poor reproduction and larval survival rates, plus increased demand and harvesting, weather, and disease. Crab harvests remain variable but high. Temperatures of Bay waters fluctuate greatly, from 0 deg.