Morro Bay's Eelgrass Beds Are Home
to a Variety of Local Residents
From the MBNEP Volunteer Monitoring Program
Spread out like grassy meadows on the mudflats at low tide, eelgrass beds comprise approximately 15% of the substrate of the bay. This submerged flowering plant grows throughout the protected shallow sub-tidal areas on the Pacific and Atlantic coasts of the United States and provides a valuable habitat. Eelgrass beds provide shelter and food for juvenile fish, mooring for fish eggs and the primary food source for black brant geese.
Morro Bay's eelgrass beds are among the largest and least impacted that remain in Southern California. Eelgrass is sensitive to slight changes in water temperature and water clarity. To aid in efforts to protect and restore eelgrass beds, the MBNEP conducts mapping and monitoring.
While out on the mudflats mapping eelgrass last fall, the MBENP staff and volunteers encountered a number of "local residents" of the eelgrass beds. Here is a sample of what we found.
This red octopus likely got stranded on the mudflats with the ebbing of a particularly high tide. They are commonly found in the intertidal zone and have been found at depths of 600 feet along the continental shelf by researchers with a remotely operated vehicle in Monterey Canyon. Octopuses have excellent eyesight, but they use their sensitive sense of touch and smell to hunt for food, typically crabs, shrimp, crustaceans and mollusks. If you encounter a red octopus while tidepooling, do not touch it! Red octopuses have sharp beaks that can crack crabshells and, if provoked, they might bite and inject venom into the wound. (Source: Monterey Bay Aquarium)
The warty sea cucumber, a close relative of sea stars and sea urchins, is soft and covered with black-tipped projections. Tube feet line the bottom of its body, and it can move at top speeds of three feet in a quarter of an hour. The sea cucumber diet consists of detritus (small particles of organic matter) and small organisms in the mud. Sometimes called the "earthworms of the sea," they take up food particles from the ocean floor much as earthworms cultivate the soil. In areas where they have been overfished, the seafloor becomes hard and is no longer viable habitat for other sea creatures. In some parts of the world, sea cucumbers are in high demand as a food and as medicine. (Source: Monterey Bay Aquarium)
The kelp crab is typically found in kelp beds and in shallow pools with abundant algae or sea grass cover. Their habitat ranges from Alaska to Baja California. Adults grow to nearly five inches long. The crabs feed primarily on kelp and algae, but if those foods are scarce, they will eat other food such as barnacles and mussels. While this animal is sensitive to wide ranges in water temperature, it does not tolerate brackish water and is found only in areas of full salinity. (Sources: University of Michigan Museum of Zoology Diversity Website)
MBNEP staff and volunteers measure the density and extent of eelgrass in Morro Bay. We return to the same spots each year to conduct these measurements. Whether monitoring water quality in the creeks, analyzing samples in the lab or tromping around on the mudflats, the volunteers of the MBNEP have donated countless hours to create a valuable set of data to help monitor the health of Morro Bay and its watershed. If you would like to join the effort, you can learn more at the MBNEP website.
Come by the Estuary Nature Center to see our live eelgrass display tank and learn more about this remarkable seagrass. The nature center is located upstairs at the Marina Square building on the corner of Embarcadero and Marina in Morro Bay. Admission is free.
More information on this and other estuary related topics can be found at the Morro Bay National Estuary Program website.
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