Variability in Microphytobenthos Biomass and Carbon Isotopic Values in Shallow Coastal Waters of the Northern Gulf of Mexico

Estuaries and inshore coastal waters of the northern Gulf of Mexico (GOM) are highly productive systems supporting diversity of life, including important fisheries species (e.g., Minello et al. 2003). Salt marshes and seagrass meadows are formed by conspicuous and high-biomass primary producers, long considered important at the base of coastal food webs (Teal 1962). However, the inconspicuous primary producers, phytoplankton and microphytobenthos (MPB, single-celled micro-algae on the sediment surface) are also important in these systems, having been shown to support a variety of consumers (Currin et al. 1995, 2011, Galvan et al. 2008). While disentangling MPB biomass and productivity rates is logistically challenging, there are many studies which suggest both phytoplankton and MPB represent a potentially large portion of primary production in these systems due to the rapid turnover rates (Sullivan and Moncreiff 1988, Blanchard et al. 2002)