RAPID Deep water Horizon Oil spill: Trophic organization of sandy beach ecosystems across gradients of development and oiling

University Of South Florida, Tampa FL

Investigators

Abstract

Intellectual Merit: Sandy beaches, one of the most abundant coastal ecosystems, contain unique biodiversity, represent ecotonal habitats and are driven by distinctive ecological processes that provide critical ecosystem services. Food webs on sandy beaches may display a high level of trophic coupling at the beach-ocean interface where consumers take advantage of the high productivity generated in coastal waters, subsidizing the shore and providing facultative, seasonal or even perennial opportunities for alternative resource use. However, many beach ecosystems are trapped in a 'coastal squeeze' between urbanization and rising sea levels. These systems are also under threat from oil extraction, as is the case for beaches in Florida and possibly the SE USA as a result of the ongoing and extensive Deepwater Horizon spill. Therefore, trophic organization of these important coastal areas may be disrupted by selected human activities. The main objectives of this RAPID project are to: (1) document the abundance of critical beach consumers, and (2) describe the trophic structure across sandy beach habitats with an emphasis on the macrobenthic fauna and in the context of potential changes resulting from acute beach oiling and/or chronic anthropogenic disturbance (i.e. development). The general sampling design calls for a series of beaches to be sampled both pre- and post oiling. The sandy beaches sampled will also span different levels of pre-spill anthropogenic disturbance (e.g., human population density, quantity of fixed structures, levels of habitat fragmentation). Characterization of the naturally occurring heavy stable isotopes of carbon (d13C) and nitrogen (d15N) will be conducted on the major benthic organisms and their food sources to 1) unravel food web structure; 2) detail the contribution of various food sources to consumer diets using 'mixing models'; and 3) evaluate variability of trophic position of major consumers, diet shifts, and subsidy integration across beaches with varying levels of development. The PIs also expect that ecosystem- level impacts of oiling as revealed via the food web may be detected with this approach. Broader Impacts: A post-doctoral associate will be trained and mentored in this RAPID project. One graduate student will be trained in field techniques and stable isotope analyses. Students conducting undergraduate research will receive training in compiling data on human usage of beaches and characterizing beach characteristics. A video documenting sampling activities and beach features will be assembled as an educational tool and will be posted on the USF, Department of Integrative Biology, website. The study will provide an opportunity for the research team to interact with a large group of local, state and federal agencies, all involved in some aspect of oil spill monitoring, assessment and clean-up. Likewise, the data collected on sandy beach ecosystem structure and dynamics can serve as a baseline for detecting future acute or chronic impacts on these coastal ecosystems. Results will be disseminated by publication in a peer- reviewed journal.