Studying the effects of habitat complexity on coral community diversity and abundance
Brittany Huntington,
PhD candidate
University of Miami
This study will use the Long Key Bridge Rubble, an existing artificial reef structure in the Florida Keys, to explore the role of habitat complexity and spatial configuration in structuring coral communities.
Coral reefs are valued as unique ecosystems with high levels of biodiversity; however, little is known about which features of reef structure are crucial in supporting the diverse coral assemblages found on these reefs. While studies have linked greater reef complexity to greater fish diversity and abundance, the role of structural habitat complexity on the stony coral community remains unclear. By utilizing an existing artificial patch reef array with varying physical structure and a distinct spatial arrangement among patches, we will test the hypotheses that greater habitat complexity (‘habitat heterogeneity hypotheses’) and great proximity to neighboring patches supports greater coral diversity and abundance. This approach capitalizes on the unique structural variations within an existing artificial reef complex to test predictions of habitat complexity that would be difficult, if not impossible, to manipulate on natural reefs. In addition, we will be able to test the impacts of patch spatial arrangement on recruitment rates and coral abundance by monitoring both ‘edge’ and ‘middle’ patches within the artificial reef complex.
Field sampling will consist of extensive surveys of existing coral reef communities across similarly sized artificial patches of varying substrate complexity and spatial configuration. Percent cover of benthic organisms and coral species richness will be determined for each patch. Lastly, rates of coral recruitment will be measured using coral settlement tiles attached to each study reef.
Initial mapping of artificial patches was completed in March 2009, and complexity of each patch was recorded. In mid-March, a 6-member dive team conducted the initial sampling of the 16 study patches. Fish counts, benthic cover, coral demography and patch complexity data was taken for each patch. Recruitment tiles could not be hammered into the concrete of the artificial reefs, hence the tiles were not deployed. We are currently testing and building alternative rigs to hold recruitment tiles for deployment at our study reefs and hope to install the tiles in early May 2009.
Given the current degradation of reefs from bioerosion, coral disease and habitat fragmentation, there is a pressing need to elucidate the importance patch quality and spatial configuration to coral community dynamics. Results from this study will enhance our ability to manage reefs for abiotic features that contribute to robust coral communities, shaping future restoration efforts and design of coral reef reserves.
