Effects of seabird nutrient inputs on the productivity of coral reef fish communities

How coral reefs can sustain their extreme biomass of large reef fishes has continued to puzzle scientists. By
living fast and dying young, small, bottom-dwelling ('cryptobenthic') reef fishes have been suggested as an
important part of coral reef productivity, fuelling the foodweb. Yet, cryptobenthic fish communities are strongly
dependent on environmental conditions, and as such their role in driving productivity of the foodweb may
change substantially if the environment surrounding them is altered. Environmental conditions on coral reefs
are dramatically influenced by the presence of seabird colonies that provide a steady influx of ocean-derived
nutrients to islands (through their droppings), which leach out to surrounding coral reefs. However, how the
presence or absence (typically driven by the presence of rats) of seabirds may affect cryptobenthic fish
communities on surrounding reefs and their role in feeding the many predatory fishes on coral reefs is currently
unknown. This study will investigate whether seabirds alter coral reef food-webs through cryptobenthic fish
communities and to what extent these changes are reversible. Specifically, the project seeks to answer the
following questions: 1) do cryptobenthic communities differ between rat-infested and seabird-dominated
islands?; 2) does this affect the productivity role of cryptobenthic fishes for larger predators?; 3) do
cryptobenthic fishes tend to replenish their own populations on a reef, or distribute among reefs?; and 4) how
does this affect the overall productivity of reefs adjacent to rat-infested vs. seabird-dominated islands? The
questions will be tackled using field-based data collection on cryptobenthic fish communities, laboratory
techniques in mass spectrometry and population genetics, and analyses of population and community
dynamics. Mentoring and professional development opportunities will be provided by leading researchers at
Lancaster University, Bangor University, and the University of Texas at Austin, and extensive opportunities for
external development via workshops, conferences, and lab visits will be offered.