Tidal Contribution to local Salt Marsh Metabolism in Santa Barbara County

Salt marshes provide critical habitat for both terrestrial and marine organisms and are sites of significant biogeochemical transformation of terrestrial material enroute to the coastal ocean. Understanding the relative importance of both river and tidal influences on salt marshes is essential to their conservation and management. In Santa Barbara County, salt marshes are largely free of freshwater input for much of the year, owing to the Mediterranean climate, and several of these estuaries close intermittently, providing a natural laboratory to separate the role of river inputs and tides in marsh ecosystem metabolism.

We deployed hydrographic sensors (PME MiniDOT loggers and Seabird 37 loggers) to compare how tides affect ecosystem metabolism in Carpinteria Salt Marsh and Goleta Slough, two similar marsh/estuarine complexes with different inlet morphologies. Here we present observations from Carpinteria Salt Marsh that illustrate variable dissolved oxygen and temperature in response to the phasing of the tides and the Sun. Low tides during local afternoon hours have high DO and temperature due to the increase of solar exposure, whereas nighttime low tides flush cool, low oxygen water from the marsh. We quantify the metabolism of each marsh and compare these neighboring ecosystems in the context of a broader synthesis of how salt marsh ecosystems function on the southern California coast. This work will advance knowledge of how to best conserve and manage these habitats.