If You Give a Clam an Estuary: The Story of Potamocorbula

Abstract

When you look at San Francisco Bay, what animals do you see? You may see lots of fish, birds, harbor seals, and sea lions. What you do not see is a little clam (Potamocorbula amurensis) that changed the Bay. Many years ago, ships accidentally brought this clam into the Bay from Asia. Soon, they spread out all over in large numbers. Clams pump water through their gills and eat small particles of food that are in the water, like phytoplankton (microscopic aquatic plants) and other microscopic critters. Potamocorbula can pump water faster than other clams, and they can eat more than their share of phytoplankton. Sometimes, Potamocorbula eats phytoplankton faster than phytoplankton can grow! What problems does that cause for other animals that also eat phytoplankton? Does Potamocorbula’s invasion only have negative impacts? In this article, we dive to the bottom of the Bay to find some answers.