Morro Bay seagrass loss causes change in fish populations

The lack of seagrass habitat prompted a dramatic shift in fish species in Morro Bay. Areas as soon as lined with lush seagrass meadows and distinctive fish species at the moment are dwelling to muddy-seafloor-loving flatfish, based on a paper by Cal Poly researchers printed within the October 2021 print version of Estuaries and Coasts.

Seagrass meadows had been beforehand widespread all through the Morro Bay estuary however practically disappeared during the last decade.

“Seagrass, like the eelgrass in Morro Bay, is important because it supports a range of marine life,” stated Jennifer O’Leary, who led the analysis as a California Sea Grant extension specialist based mostly at Cal Poly. O’Leary is now the Western Indian Ocean coordinator for the Wildlife Conservation Society. “It’s like the trees in a forest–these underwater plants provide food, structure, and shelter to many of the marine animals that live in the bay.”

Underwater seagrass meadows are one of many most important habitats in coastal estuaries, and characterize probably the most biologically productive biomes on our planet. Yet seagrass habitats are being misplaced at an alarming charge, and their decline now rivals these reported for tropical rainforests, coral reefs, and mangroves. Loss is normally the symptom of a bigger downside, and seagrasses are subsequently thought-about “coastal canaries.” Their decline alerts vital losses to biodiversity and infrequently impacts the communities that rely upon them.

Morro Bay, one among 28 estuaries that the U.S. Environmental Protection Agency designated as vital to the financial and environmental well being of the nation, has seen a dramatic loss in its seagrass habitat. Once dominated by a standard California eelgrass (Zostera marina), seagrass at this web site has declined by greater than 95 %, from protecting 344 acres in 2007 to lower than 15 acres in 2017.

Seagrass meadows are a multifaceted habitat that safe sediments with their root techniques, and supply meals, shelter and nurseries for a lot of forms of fish and invertebrates. When seagrass meadows are misplaced, they’re usually changed with a much less dynamic, muddy seafloor habitat.

O’Leary and colleagues discovered that seagrass loss didn’t lead to fewer fish however reasonably led to modifications within the forms of fish that dwell within the bay. The analysis crew noticed reducing numbers of some seagrass-specialist fish species, such because the bay pipefish (Syngnathus leptorhynchus). With lengthy skinny our bodies and olive inexperienced coloration, bay pipefish are tailored to cover among the many seagrass blades.

In distinction, researchers noticed a rise in flatfishes just like the speckled sanddab (Citharichthys stigmaeus) and staghorn sculpin (Leptocottus armatus). These fish have flat our bodies that are perfect for life alongside the muddy seafloor and are widespread residents in California bays and estuaries. These species have moved into the previous eelgrass habitats and now make up the vast majority of the fish species current in Morro Bay.

The lack of eelgrass habitat alongside the California coast presents a bigger downside for species that rely upon seagrass, just like the bay pipefish. If seagrass doesn’t get well, then the surviving meadows will probably be additional aside and have a extra fragmented, or patchy, distribution. This distance and patchiness of habitat might impression specialists, like pipefish, by impairing their means to maneuver to a brand new habitat to seek out meals or mates. This neighborhood isolation might alter the genetic construction and variety of the general pipefish inhabitants over time.

“The relatively sudden and near complete collapse of eelgrass in Morro Bay has not only changed fish populations, but it has also resulted in substantial changes to estuary physics and geomorphology,” stated research coauthor Ryan Walter, a Cal Poly physics professor who has been finding out eelgrass loss by means of a California Sea Grant-funded analysis undertaking that was launched in 2018.

Walter, O’Leary and different Cal Poly researchers, in conjunction with the Morro Bay National Estuary Program, proceed to check the trigger and penalties of the eelgrass decline. In one other research, the crew just lately discovered that the lack of eelgrass in Morro Bay led to widespread erosion, or lack of sediment, all through the estuary.

The new analysis sheds further mild on modifications inside Morro Bay which will inform how scientists find out about seagrass communities all through California. There has not been an eelgrass decline on the United States Pacific Coast of this magnitude, making Morro Bay a novel occasion which will assist predict future estuarine change.

A multifaceted strategy to guard and improve the remaining seagrass will probably be important, stated the researchers There is hope for the long run because the remaining eelgrass is slowly increasing with safety and native planting initiatives, together with profitable transplant efforts led by the Morro Bay National Estuary Program. Walter and O’Leary have used drone-based surveys to doc pure enlargement and restoration of eelgrass in areas the place it was misplaced. The mere 9.4 acres of seagrass left in Morro Bay in 2017 expanded to 36.7 acres by 2019. The researchers are nonetheless analyzing information from 2020 however are optimistic that the seagrass acreage continues to slowly enhance.

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