Living and fossil epiphytal ostracodes were investigated from central and eastern Florida Bay to determine historical trends in seagrass and macro-benthic algal habitats during the past century. Living assemblages collected in February and July, 1998 from 15 sites throughout Florida Bay revealed that Loxoconcha matagordensis and Malzella floridana are the dominant species living on Thalassia and that Xestoleberis spp. is the most abundant ostracode group living on Syringodium and marine algae such as Chondria. Peratocytheridea setipunctata is a species that is common on muddy substrates and on Halodule.

Temporal trends in epiphytal ostracodes were reconstructed from radiometrically-dated sediment cores from Whipray mudbank, Russell Banks, Bob Allen mudbank, Pass and Park Keys, Taylor Creek (near Little Madiera Bay) and Manatee Bay. The results show that there have been frequent changes in the relative frequencies of L. matagordensis, M. floridana, and Xestoleberis over the past century. Prior to the mid-20th century, seagrass- and algal-dwelling ostracode species were relatively rare at our sites in central and eastern Florida Bay. Ostracode assemblages living between about 1900 and 1940 were characterized by moderate to large proportions (10 to >60 percent) of Peratocytheridea setipunctata when Thalassia and macrobenthic algal species were significantly less common than during the later half of the 20th century.

Beginning about 1930, and continuing until 1950, P. setipunctata populations experienced significant declines while L matagordensis and Xestoleberis increased progressively from 0-10 percent to >25-40 percent, depending on the site. This long-term faunal shift in central Florida Bay suggests that there has been a much greater abundance and/or density of subaquatic vegetation over the past 50 years compared to the prior half century. Since 1950, our sites in central and eastern Florida Bay have experienced high amplitude swings in the proportion of seagrass and macro-benthic algal-dwelling species suggesting subaquatic vegetation has been extremely dynamic both spatially and temporally over decadal timescales. Some of these oscillations, such as the decline in L. matagordensis, Xestoleberis, and M. floridana during the 1970’s and early 1980’s, appear to be synchronous across the study area and may represent large-scale dieoffs.

(This abstract was taken from the Greater Everglades Ecosystem Restoration (GEER) Open File Report (PDF, 8.7 MB))

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