DEL MAR — Eight months after being open to the ocean tides for the first time, the new coastal lagoon built in Del Mar is now home to millions of fish and invertebrates.
Southern California Edison and its partner, SDG&E, are paying to construct the new wetlands as mitigation for impacts from their San Onofre Nuclear power plant that produces electricity approximately 40 miles north of the site.
Scientists from the University of Santa Barbara’s Marine Institute, under contract to the California Coastal Commission, have been independently monitoring the new lagoon. A first inspection in late January, after the lagoon was constructed but not yet opened to the ocean, revealed no fish or invertebrates. But in late June, scientists tested again and discovered more than 4 million fish and countless invertebrates in the new lagoon. By August, scientists discovered that the number of fish had doubled in the new lagoon, with volumes being estimated at close to nine million fish.
“We are encouraged by the quick manner in which these species are rushing in from the ocean to fill the new wetlands,” Patrick Tennant, project manager for Southern California Edison, said. “It bodes well for the new sections of the wetlands project we plan to open in November.”
Species found in the new lagoon include goobies, flatfish, pipe fish, (a relation to the sea horse), mullet and grunion. Invertebrates discovered include snails, clams, worms and mussels. In June, the number of fish, snails and clams was estimated to be almost equal to the Fish and Game lagoon next to the new lagoon, which scientists have used as a natural control. Today, the fish population is more than double the control lagoon.
Gathering facts about numbers and types of fish, seasonality of fish counts, size and the health of different species are ways that scientists can document the way fish and invertebrates (important food resource of fish and birds) recolonize and populate. But the task of monitoring one of the largest, man-made coastal lagoons over the next several decades is a difficult one. Scientists at the lagoon have been motivated to invent a new way to field test different equipment for counting the numbers and variety of fish by constructing a large, plastic cylinder that is inserted into the water with a net inside that than can be triggered to capture fish without harming them. One of the most important goals is food chain support for bird populations, so the millions of baby goobies in the lagoon are an excellent sign of sustainability, since they are considered at the bottom of the food chain.
Monitoring and testing of the lagoon will continue for the next several decades, giving scientists and marine estuary planners ideas on best restoration practices for other coastal lagoons.