When algal blooms die and decay, they deplete the dissolved oxygen in the water. Nutrients can come from sewage treatment plants, fertilizers, and even vehicle exhaust. Sediments can cloud the water, making it difficult for plants such as underwater grasses to receive enough sunlight to survive. Water temperature affects when animals and plants feed, reproduce, and migrate. During spring and summer, the shallow water areas are often warm, while the deepest waters are cold.
Salinity greatly determines where plants and animals live within the Bay.
Bay organisms that can live upstream in freshwater often cannot survive in the saltier waters of the lower Bay. Likewise, salt water organisms are usually not adapted for freshwater. Dissolved oxygen is essential for animals living within the Bay. Underwater plants produce dissolved oxygen for the fish and other animals to breathe, thereby helping to maintain a healthy ecosystem.