Can Florida's Springs Coast provide a Potential Refuge for Calcifying Organisms? Evidence from Benthic Foraminifera

• Main Author: Amergian, Kyle E.
• Format: Thesis
• Language: unknown
• Published: Digital Commons @ University of South Florida 2019
• Subjects: Archaias angulatus; bioindicator; Distribution; Miliolida; refugia; Other Oceanography and Atmospheric Sciences and Meteorology; Ocean acidification
• Online Access: https://digitalcommons.usf.edu/etd/8619; https://digitalcommons.usf.edu/context/etd/article/9816/viewcontent/Amergian_usf_0206M_15699.pdf

Florida’s Springs Coast, located in the northeast Gulf of Mexico, includes an extensive system of salt marshes that discharge millions of liters of fresh water into coastal waters daily. The chemical properties of the spring waters include high alkalinity and high calcium concentrations due to the Paleogene limestone lithology of this region of Florida. Benthic foraminifers, which are recognized as ecologically important bioindicators, occur abundantly on the shallow shelf off the Springs Coast. Based on the prevalence of the benthic foraminifer Archaias angulatus in the seagrass beds along this shallow shelf, a previous study proposed that the Springs Coast provides favorable conditions for such “subtropical” calcifying organisms, despite existing literature indicating that salinities and winter temperatures are suboptimal for such species. Thus, a motivation for my study was to provide insight into the hypothesis that, during times of ocean acidification, limestone lithofacies may provide suitable water chemistry and physical habitat to provide refuges for calcifying organisms. Selected environmental parameters and sediments from 41 sites at depths <8 m were sampled in September 2013, during routine seagrass monitoring by researchers from the Florida Fish and Wildlife Research Institute. The 152 benthic foraminiferal species identified included 71 porcelaneous, 67 hyaline, and 14 agglutinated species. Overall, 74% of the specimens identified were porcelaneous and most of the remainder were hyaline; agglutinates composed <1% of those counted. Species dominance in samples revealed an apparent distribution reversal compared to previous reports from Gulf of Mexico coastal habitats. Smaller miliolids, notably Quinqueloculina spp., dominated in samples from most of the inshore brackish sites. In contrast, at the more offshore sites characterized by normal marine salinities, hyaline taxa such as Haynesina spp. were much more abundant. We postulate that these unusual distributions are associated with the calcium ...