Species and food webs

Puget Sound hosts more than 100 species of seabirds, 200 species of fish, 15 marine mammal species, hundreds of plant species, and thousands of invertebrate species (Armstrong et al. 1976; Thom et al. 1976; Canning and Shipman 1995). Visit our species page for a full list. The array of species found in Puget Sound reflects its high productivity, the wide diversity of habitats present, and its unique geographic location at the interface of “northern” and “southern” ranges for many species. These species do not exist in isolation, but rather interact with each other in a variety of ways: they eat and are eaten by each other; they serve as vectors of disease or toxins; they are parasitic; and they compete with each other for food, habitat, and other resources.

There is no single food web in the Puget Sound ecosystem. Instead there are many marine food webs that reside in the soft-bottomed nearshore, in rocky-bottomed areas, in habitats dominated by eelgrass or kelp, and in pelagic areas as well. Similarly, there are terrestrial and freshwater aquatic food webs that occur in alpine habitats, mid-elevation and lowland forests, and rivers, lakes, and streams. The food webs in each of these areas are not discrete and independent, but rather are highly interconnected by organic matter sources, physical proximity, exchange of water, and organisms that change habitats during the course of their life cycles.

Food webs also change both in time and space due to variation in stratification, prey availability, organic-matter source availability and quality, and other local and regional conditions. In addition, some species occupy multiple places or play multiple roles in the food web depending on their life stage, size, habitats they occupy, and time of year.

Sources:

Sound Science: Synthesizing ecological and socioeconomic information about the Puget Sound ecosystem. Published 2007. Used by permission.

Overview

The health of an ecosystem is tied closely to the health of its food webs. This article provides an overview of the concept, origin, and characteristics of a food web and how predator and prey relationships are shaped in the Salish Sea.  

Bear eats salmon. Photo: Robert Voors (CC BY-NC-ND 2.0) https://www.flickr.com/photos/robert_voors/1303192433

Related Articles

As observed in Hood Canal, low-oxygen conditions can upend the lives of Dungeness crabs trying to stay alive. Levels of dissolved oxygen can alter predator-prey relationships for a multitude of species, affecting populations throughout the food web. Part two of our series "Oxygen for life" examines a crab case study.

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How do excess nutrients trigger low oxygen conditions in Puget Sound and what do those conditions mean for the species that live here?

Diverse communities of microscopic organisms called phytoplankton make up the base of the aquatic food web. In that role, they are essential to the tiny animals that eat them, but phytoplankton are not dependent on others. Thanks to chlorophyl, these tiny organisms can generate their own energy from nutrients and sunlight. Despite their critical importance to a great diversity of sea life in Puget Sound, phytoplankton can also contribute to low-oxygen conditions, and some can be harmful in other ways.