Estuaries are unique and important coastal ecosystems that reside at the interface of inland freshwater habitats and saltwater marine habitats. Many people know of and have visited the larger central coast estuaries including Elkhorn Slough and Morro Bay but fewer people realize that there are many smaller river mouth estuaries along our coastline.
Just as our larger estuaries, these river and creek mouths act as mixing zones where freshwater flowing to the coast mixes with ocean waters, providing unique habitats for a variety of flora and fauna.
For all these estuaries, human impacts come from both land and sea. Water draining from the watersheds delivers pollutants to these estuaries where they often accumulate before flowing to the ocean. Because estuaries lie along the coast where people want to live and recreate, many have seen significant impacts from development. Agriculture, urban development and recreational infrastructure including parking lots and bridges that aid visitors’ access to these beautiful coastlines also cause impacts.
Loss of estuarine habitat can affect the species that live there, reducing areas for feeding and breading that can reduce species numbers and health. Fishing similarly impacts species within these systems. For species that migrate between estuaries and to offshore habitats, local fishing can cause harm to marine systems throughout the region. Fortunately, California has led many initiatives to protect these habitats and in time to reduce impacts, returning lost areas to productive habitat.
As with offshore habitats, California has also established a network of estuaries along the coast where fishing is restricted to ensure that species that rely on these habitats for reproductive success have sanctuaries to help retain coast wide populations.
These oddly named Estuarine Marine Protected Areas have been a part of the marine protected area program for a decade but unlike offshore MPAs that have been monitored for many years, EMPAs have yet to be monitored in a standard and consistent manner. Last year, however, our group at Moss Landing Marine Labs was awarded funding by the Ocean Protection Council to build this monitoring program and help document the current condition of these systems and the long term benefits of marine protected area designation.
California has 23 outer coast estuarine marine protected areas including the local Elkhorn and Moro Cojo sloughs as well as the Russian River, Morro Bay and Goleta Slough. About two-thirds of these marine protected areas are larger bay-like estuaries and one-third are river mouth or lagoonal systems. Kevin O’Connor at Moss Landing Marine Labs notes that “designing a monitoring program that can study this diversity of estuaries is challenging and we are fortunate to have a strong team of scientists throughout California working on this project”.
The science team, including researchers from UC Davis run Bodega Marine Lab, Sonoma State, San Jose…