Intra- and inter-habitat variation in macroalgae and coral diversity in the Bahamas Biosciences, University of Exeter, Exeter Abstract Macroalgae and coral are vital components of the marine environment, providing primary productivity and diverse interconnected habitats utilised by a huge variety of fish and other species. Diversity of coral and macroalgae on reefs is a large factor in the survival and success of the habitats which they form, with disruptions to the balance of diversity and richness having serious knock-on effects for entire food webs and the local economies which depend upon them. We studied the diversity of macroalgae and coral in a range of environments on the island of San Salvador, Bahamas to determine if there were differences both within and between habitats. Doing so gives us important indicators as to whether additional, unknown factors, potentially anthropogenic, are influencing these crucial biomes. Method Data-gathering was split into two parts, one for coral study and one for macroalgae. Data was collected over two main sites, designated Site 1 and Site 2. For macroalgae, diversity data was studied at both seagrass and coral dominated parts of the sites – giving four sets of data. Coral diversity was only studied on the coral reef areas of the sites. 25X25cm quadrats were placed randomly in each habitat, before being photographed. Vidana software was used to analyse each photo and produce percentage cover of different coral/algal species contained within the quadrat. For each quadrat, a Shannon-Weiner diversity index was calculated and the results tabulated. SW was favoured as it take into accoutn both abundance and species richness. A one-way ANOVA test was used on the coral SW data (as inter-habitat variation was compared), and a two-way ANOVA test on the macroalgae data (as intra- and inter- habitat variation was compared). Standard error was used where appropriate, to adjust for variation in sample size and to best demonstrate the deviation from the mean. Results It was found that Coral diversity (Fig.1) was not significantly different between the two different sites that were surveyed (p=0.848) Standard error= (site 1) & (site 2). Conclusion Whereas inter- and intra- habitat variation did little to influence the diversity of the macroalgae, the combined effect was significant. There are a variety of factors which may be responsible for this. It is clear that, overall, site 2 had a higher average variation. However, although macroalgae diversity at site 1 was higher at the reef seagrass habitat than the coral habitat, it is the opposite at site 2. REASONS WHY References DO REFERENCES Site 1Site 2 Seagrass1213 Reef310 Fig.3: Total Number of Different Macroalgal Species in Each Habitat It was found that variation in Macroalgal diversity (Fig. 2) was significantly different (p=0.042) for intra- and inter- habitat variation combined. However, variation was not significant between habitat or site individually (p=0.704 & respectively). The reef habitat of site 2 had the highest average diversity (0.654), whereas the reef habitat of site 1 had the lowest (0.533). Standard error (in order of left to right on x-axis)= 0.056, 0.049, 0.039, Fig.3 shows the total number of different macroalgal species recorded was highest at the seagrass habitat of site 13, and lowest at the reef habitat of site 1. Student no.: