The Research Problem

We are interested in processes that underlie food webs across the Hawaiian Archipelago, and our primary research lies in two areas:

1. to determine the impact of terrestrial (land) nutrient sources on near shore coastal ecosystems with special emphasis on the role of sea birds in subsidizing coastal food webs; and
2. to determine how coral type and topography influences small scale nutrient exchange on coral reefs. In particular we are pairing our research with the Donahue lab to examine how coral topography and crevices influence small-scale chemical conditions and how these in turn influence bio-erosion of the reef matrix.

Methods

To study these problems we combine sensor data on flow and chemical conditions on the reef with molecular or other biological data to examine the interaction of physics, chemistry and biology in a natural ecosystem.  To examine the effects of bioerosion we combine our data with measurements of bioerosion rates and species composition of eroding communities.

To determine the role of terrestrial (land) sources on coastal food webs we are combining, local physical and chemical data with isotope analysis and the use of microbial source tracking that allows us to determine the sources of bacteria in the water using organism specific molecular tracers. Combining this molecular data with information on currents and chemical conditions in the water will allow us to estimate the degree to which seabirds and other organisms contribute to the local coastal nutrient loads.

Findings

We have just completed our first cruise to the Northwestern Hawaiian Islands (Papahānaumokuākea Marine National Monument) and are awaiting the return of samples and data so that we can begin to analyze our results.  Our preliminary results show that there is a great deal of small-scale variation in the physical environment across the reef and that these are correlated to variations in chemical condition such as local pH.

Importance

Understanding how the physical and chemical environment interact on a reef and how this interaction varies across reefs of different structure and exposure to terrestrial input will tell us much about what underlies food web structure in coral reef systems.  Understanding this basis for the food web will allow for greater prediction of the impact of perturbations to the food web and the physical environment associated with anthropogenic influence and global shifts in climate.