An Overview of Estuarine Ecology

As a part of a complex marine ecosystem, shellfish provide several functions. In the food web, they serve as food for carnivores, like crabs, in nearshore habitats. Their larvae also provide food to a variety of fishes. For human benefit as an ecosystem service, oysters filter the water in which they live.

Due to the energy differences in parts of the Puget Sound, sediment of different sizes settles in different places. Species capitalize on these differences and establish niches in the different layers or locations of sediment. Geoduck clams are abundant in the south sound, deeply buried in the mud or sand in the low intertidal and subtidal zones. Olympia oysters are found in shallow subtidal muddy habitats. Larvae settles onto pieces of harder substrate.

Humans pose a specific threat to this habitat due to increased sediment runoff from development and urbanization. Because they grow in distinct sediment types, any alterations to sediment amount or grain size can have a negative impact on populations. Changes in water column characteristics like temperature, salinity, turbidity, oxygen, pollutants and food types and concentrations also pose a threat to the balance of the ecosystem.