:: LINE ISLANDS EXPEDITION: CORAL HEALTH IN THE SOUTH PACIFIC ::

Analysis of these data will allow us to answer several questions that are crucial to the conservation and restoration of the world's coral reef environment. By focusing on the data from the undisturbed reefs of Palmyra and Kingman, we will provide the best-available baseline data regarding the functional characteristics of healthy coral reef ecosystems, in particular focusing upon the distribution of groups of organisms on the reef. By repeating our detailed ecosystem surveys across a gradient of anthropogenic disturbance, we will reveal the ecosystem functions and services that are most vulnerable to human activities. In particular, we will gain a unique view into the groups of organisms that are lost, the species interactions that are altered, and the changes in the trophic dynamics as a reef changes from pristine to disturbed, across an increasing gradient of human involvement. This study will be the first of its kind to control for biogeographic differences among sites, to include such a broad taxonomic sampling, and to include truly pristine reef sites into analysis of human impacts on coral reefs.

The four hypotheses posited by Jackson and colleagues (see above) will be addressed through the following analyses of our data:

Loss of megafauna
We will compare the size-frequency distributions of the fish communities across the transect of disturbance. Our expectation is that on pristine reefs, the majority of the biomass will be comprised of large-bodied individuals. In contrast, harvest by humans will reduce the average size of fish within the community, resulting in a ?left-shifted? size-frequency distribution.
Change of food web structure
Pristine food webs are dominated by long-lived, large-bodied, predatory species. As such, a classic food pyramid will appear inverted, with the higher trophic levels comprising the majority of the biomass in the ecosystem. Because humans disproportionately deplete larger, predatory species, we expect the distribution of biomass to shift to lower trophic levels, including small-bodied vertebrates and invertebrate species, resulting in a more classically shaped biomass pyramid to be present in more stressed ecosystems.
Decreased energetic efficiency
Ecological theory of marine ecosystems suggests that smaller, faster-moving organisms are less efficient at using energy (and hence they are less productive) than are larger organisms. Additionally, the high turnover of microbial species leads to higher rates of energetic loss from the ecosystem. Through analyses of the size structure of the algal, invertebrate, and fish community, and through estimations of microbial density, we will test for systematic changes across the transect of human disturbance.
Loss of habitat complexity
Hermatypic corals are the dominant producers of habitat structure and complexity on tropical reefs. As such, factors that decrease the abundance and the productivity of corals also lead to the reduction of structural accretion. We will test for patterns of change in coral abundance and of coral health across the Line Islands to test for effects of human disturbance on the rate of habitat generation, and therefore, the maintenance of habitat complexity.

DATA ANALYSIS