Exploring California’s Marine Protected Areas: South Humboldt Bay State Marine Recreational Management Area (Part Two)

staghorn sculpins
Pacific staghorn sculpins (Leptocottus armatus). The species name armatus is Greek for “armed,” referring to the antler-like spines on the fish’s gill covers. photo by F. Shaughnessy

This is Part Two of a special installment of the California Department of Fish and Wildlife series, Exploring California’s Marine Protected Areas. Part One of the installment investigated what makes this bit of estuary special and the protections that are in place to safeguard it. This final installment takes an inside look at recent research documenting the current state of the marine recreational management area.

crab in trap
Juvenile Dungeness crabs (Metacarcinus magister) collected as part of the study. photo by F. Shaughnessy

On an early, and uncharacteristically sunny, late spring morning on California’s north coast, I joined a team of researchers to conduct scientific monitoring in South Humboldt Bay State Marine Recreational Management Area (SMRMA). As with other estuarine marine protected areas (MPAs) and additional sites in this study, the team sought to catalog the diverse algae, plants, invertebrates, and fish in South Humboldt Bay SMRMA, along with the abundance and size class structure of target species including eelgrass, crabs, and salmonids.

The seining, trapping, and quadrat fieldwork that I helped with on that sunny morning revealed a vibrant community in Humboldt Bay. Eelgrass beds (Zostera marina L.) occur in the lower intertidal area, whereas the mid-intertidal mudflats were covered by green algae (Ulva torta and Rhizoclonium tortuosum) and the red alga Gracilaria pacifica. Directly or indirectly, these primary producers support a diverse assemblage of invertebrates, such as clams (including the bent-nose macoma, Macoma nasuta and purple dwarf-venus Nutricola tantilla), Dungeness and red rock crabs, polychaete worms (such as Mediomastus californiensis and Lumbrineris zonata), and crustaceans like the eelgrass isopod and the amphipod commonly called skeleton shrimp (Caprella californica). The smaller of these animals are likely prey for the many fish found in the study, such as topsmelt, surfperch, bay pipefish, bay gobies, penpoint gunnels and staghorn sculpins.

isopod
An eelgrass isopod (Idotea resecata), including “eyed” herring eggs (the eyes of the young herring are visible through the sides of the egg) latched onto its body. photo by J. Ray

The sampling period for this work included two years of drought (2014 and 2015) and one year of El Niño conditions (2016). According to study leader Frank Shaughnessy, there were no large changes in the composition or abundance of these community members when the climate shifted from drought to El Niño conditions. This is likely due to the fact that all of Humboldt Bay, and particularly the location of the South Humboldt Bay SMRMA, is very minimally influenced by freshwater flows from tributaries. Minimal freshwater influence makes Humboldt Bay quite different from other estuaries investigated in this study (Big River, Ten Mile River, and Mad River estuaries), where the freshwater contribution and the estuarine community did change among years.

gunnel
Penpoint gunnels (Apodichthys flavidus) commonly take on the color of the surrounding vegetation, such as eelgrass. photo by F. Shaughnessy

The project is one of many in the California Baseline MPA Monitoring Program, which is administered by California’s  Department of Fish and Wildlife and Ocean Protection Council, the Ocean Science Trust, and California Sea Grant, and aims to create a benchmark of ecological and socioeconomic conditions inside and outside of California MPAs. Results from this research will be available through California Sea Grant and posted on OceanSpaces.org in Spring 2017, including the data and a peer-reviewed technical report.

MPA map
California’s statewide MPA network. map by CDFW Marine Region GIS Lab

California’s network of 124 marine protected areas (MPAs) collectively aims to protect marine resources for various purposes including enhancing natural diversity and abundance of marine life, sustaining and rebuilding species of economic value, and improving recreational and educational opportunities in areas subject to minimal disturbance. The South Humboldt Bay SMRMA is one of 22 estuarine MPAs in California which, along with the other 102 MPAs between the mean high tide line and three nautical miles offshore, were designated by the California Fish and Game Commission to help achieve these purposes.

The study described here was led by Dr. Frank Shaughnessy of Humboldt State University (a California State University campus) in collaboration with H.T. Harvey & Associates, the Wiyot Tribe and the University of California, Davis Bodega Marine Laboratory.

 Read Part One of this article, which takes a look at the unique habitats in the SMRMA and the protections in place to safeguard them. More information on California’s MPAs can be found in the California Department of Fish and Wildlife series, Exploring California’s Marine Protected Areas.


post by Adam Frimodig, CDFW Environmental Scientist

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