EAPSI: Comparing Food Webs on Natural and Man-Made Shorelines in Sydney Harbor

Heery Eliza, Friday Harbor WA

Investigators

Abstract

Shorelines in coastal cities are heavily modified by introduced, man-made structures. These structures support novel assemblages of marine organisms, but their impact on marine food webs is unknown. This project will use modern chemistry techniques to characterize marine food webs on natural and man-made shorelines in Sydney Harbor. The study will be conducted under the guidance of Dr. Emma Johnston, a pioneer in studies of urban marine ecosystems, who has advanced the field through an extensive publication record and a strong commitment to communicating science to the public. Findings from the study will provide insight into the effects of urban shoreline development on food web complexity and the ecological goods and services that marine ecosystems provide. We will use stable isotope analysis to compare trophic linkages within two types of urban marine habitats: hard-bottom substrates (man-made seawalls versus natural rocky shorelines) and soft sediments (where artificial structures have been added versus where they are absent). Research on these habitats in Sydney Harbor is unparalleled compared with other coastal cities; this will allow the researcher to develop conceptual food webs and identify key species for stable isotope analysis based on past literature prior to collecting tissue samples. Selected organisms will be collected from random quadrats and sediment cores at three sites in Sydney Harbor and their tissue will be analyzed for carbon and nitrogen ratios using a new elemental analyzer at the University of New South Wales. The researcher will use mixing models to determine the relative trophic position of each organism sampled and derive trophic webs and isotopic niche calculations. Resulting quantified food webs will then be compared between habitat types to evaluate the effect of man-made shorelines on food web relationships and ecosystem complexity. This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the Australian Academy of Science.