Martha Zapata- Graduate Program Exit Seminar
A Graduate Program Exit Seminar by Martha Zapata will be presented Friday, December 15th, 2017 at 9:30am in Heffner Wetland Building Room 128. Her presentation will be Aquatic-terrestrial trophic linkages across salinity gradients of the Fakahatchee Strand and Ten Thousand Islands Estuary Florida, U.S.A.
Abstract: The movement of organisms between habitats is a critical facilitator of biological connectivity in estuaries yet little attention has been directed towards linkages between aquatic and terrestrial zones. To address this knowledge gap, I addressed the following questions: (1) How do the abundance, community composition, and individual traits of emergent aquatic insects vary seasonally across an estuarine salinity gradient? (2) Are trophic dynamics and body condition of nearshore orb-weaving spiders associated with temporal variability in salinity gradients as mediated by emergent insect subsidies? My study system was the Fakahatchee Strand and Ten Thousand Islands Estuary of southwestern Florida, where I quantified and characterized emergent (i.e., adult) aquatic insects and insect-facilitated subsidies to terrestrial consumers (i.e., orb-web spiders) during the summer and winter seasons (2015-2016) at freshwater, mesohaline, and polyhaline habitats. My findings suggest that salinity, driven by wet-dry seasonal hydrology and El Niño Southern Oscillation events, drive emergent insect communities. In turn, spatial and temporal variability in the abundance and traits of emergent insects were strongly related to spider reliance on aquatic subsidies, trophic position, and body condition. These results suggest that salinity-mediated subsidies are likely to influence a suite of other terrestrial insectivores including bats, birds, lizards, as well as important ecosystem processes including nutrient cycling, biomagnification of contaminants, and maintenance of biodiversity. An improved understanding of seasonal subsidy dynamics in estuaries will help forecast and manage functional ecosystem responses to environmental disturbances (e.g., sea level rise).