[RESOURCE] Human Impacts on Coral Reef Biodiversity: Are Responses In Species Richness Comparable Across Size Classes of Associated Species?

INTRODUCTION Coral reefs are regarded as the most species rich ecosystems in the oceans but they are also probably the most threatened (e.g. Carpenter et al., 2008 Science 321: 560-563). Whilst patterns of biodiversity are well studied for some groups of coral reef organisms, especially reef-forming corals, fish and some benthic megafaunal components, the diversity and distribution of many groups within the so-called cryptofauna are poorly studied and baseline diversity is not well understood (Knowlton & Jackson, 2008 PLOBiol 6: e54; Plaisance et al., 2009 Coral Reefs 28: 977-986). As a result we have a poor understanding of the overall implications of human impacts on coral reefs for biodiversity. This project will focus on assessment of the diversity of select groups of reef cryptofauna and examining the relationship between this component of biodiversity and that of reef-forming corals, fish and conspicuous megafauna on relatively pristine to relatively impacted corals reefs. Survey methods, based on line transects and quadrats on the leeward side of outer reefs, will be used to survey the diversity of corals, fish and conspicuous megafauna. These will be compared with studies on the cryptofauna of collected dead coral heads, coral rubble and sediment using a combination of morphological and molecular methods. HYPOTHESES This project will be focused on testing two hypotheses: (i) That the cryptofauna of coral reefs, inhabiting a variety of sub-habitats has a high level of species richness across multiple taxa and size classes of organisms. (ii) Based on previous studies (e.g. Sandin et al., 2008), the response of different taxa to human impacts differs significantly. We also expect responses in different ecological guilds of species to differ to impacts (e.g. grazers, predators, detritus feeders, suspension feeders). METHODS The project will compare biodiversity on relatively pristine coral reef environments compared to those that are impacted to various degrees. Locations that will be compared include: Chagos Archipelago (low impact), Madagascar (moderate impact), and the Philippines (heavy impact). Alternative sites should any of these prove impractical are the Seychelles and/or East Africa. Assistance in fieldwork from the CASE partners, ZSL, and availability of expeditions will determine the exact locations of this work. Assistance will be obtained from partner NGOs working within these regions. Coral reefs will be assessed for water quality through field measurements. Observations of coral mortality, evidence of reef fishing, presence of algae and community structure of fish will help to assess reef condition.The leeward side of outer reefs will be surveyed using transects employing digitally photographed Line Intercept Transects to record % cover of substratum and Underwater Visual Census (UVCs) using belt transects to assess the diversity of fish communities. Quadrats will be used to survey megafaunal invertebrates. Dead coral heads will be collected, as well as collections of rubble and sediment made. Animals will be extracted from coral and rubble in the field. Sediment samples will be preserved and transported to Oxford. Molecular barcoding methods will be used to assess the diversity of select groups of cryptofauna extracted from coral and rubble. Sediment will be subject to extraction of environmental DNA and, if additional funding is obtained from the NERC high-throughput molecular facilities, analysed using hypersequencing. OUTCOMES The studentship should provide valuable data on the magnitude of diversity comprised by elements of the reef community that are rarely studied. Data obtained on human impacts on corals reefs on reef cryptofauna, in comparison to other size classes / guilds of reef organisms will be novel and of immediate importance in monitoring and management of coral reefs. The project will contribute new information on taxonomy and to sequence databases of reef organisms.