Biodiversity of Borneo Project 2: Coral Reefs Coral Diversity Study Comparison of Coral Diversity Across Three Reef Habitats Marcel Alfasisurya.S.A, Ross McFarland, Charlie Ryland, Olivia Tandon, Kore Tau Abstract: We sampled twelve 10 meter coral transects, four in each of three different habitat types: the fore reef, reef crest and back reef. We looked at the differences in coral coverage and compared the formation types between the three habitats. Although we did not find a significant relationship in the total coverage type, the live coral coverage was slightly biased towards the fore reef, suggesting that this may be a more diverse habitat for corals than the crest or back reef. Introduction: Coral reefs are some of the most diverse places on Earth, supporting an extreme abundance of life. According to Allen and Steene, coral reefs are extremely complex systems that provide many different microhabitats. They further state that it is these microhabitats that lead to the large number of species found on the reefs (Allen and Steene, 2003). In this project, we examined differences in the coral diversity on the fore reef, reef crest and back reef, using a transect method, in Malahom Bay Marine Park, Sabah. Using 10 meter transects, we measured the coverage of different coral forms, as well as the percentage of the sea floor that was covered with dead coral, rocks or sand. Reefs with many different types of coral may provide more microhabitats for fish and invertebrates on the reef, so analyses like this one can be instrumental in determining reef health. According to Karlson et al, coral diversity is not evenly ditributed across different habitat types (2004). Furthermore, we know that different levels of disturbance favor different coral types (Webb, lecture 8/8/07), so we would expect more exposed areas of the reef to contain hardier corals, while more protected areas should contain more delicate coral forms. Thus we hypothesize that the back reef, which is more protected, will have more branching coral, which is more easily broken, and the fore reef will have more massive and submassive corals, which are hardier. Methods and Materials: To achieve our goals in this project we used a line transect study method. This involved laying a series of transect lines across the reef at 3 different zones. These lines were each 80m and then four 10m sections from each were analyzed for coral content and diversity. These analyses used the distance that each sea floor feature, including corals, occupied along the transect. The value for the measurements was recorded in cm of cover along the measuring tape. Using the computational program 'R,' we were able to input the data gathered from the transects and analyze the correlation between reef zones and relative diversity. (see Appendix 5 for script) Results: see Appendices 1-4 Discussion: Our cluster analysis showed no obvious differences between transects of differing habitats. Slight difference suggested that the fore and back reef were more similar to each other than either were to the crest reef. Ordination of the live coral in these habitats attributed at least some of this clustering to foliose coral formations in the crest habitat. Furthermore, the live coral ordinanation shows greater
clustering amongst the back reef transects than among the fore reef ones. This suggests a greater variability in the sloped fore reefs than the back reefs. Sources: Allen, Gerald R and Roger Steene. Indo-Pacific Coral Reef Field Guide. Tropical Reef Research, 2003, 5. Karlson, R. H.; Cornell, H. V. & Hughes, T. P. (2004), 'Coral communities are regionally enriched along an oceanic biodiversity gradient.', Nature 429(6994), 867--870. Webb, Cambell. Lecture notes. August 7, 2007.
Appendix 1
Appendix 2
Appendix 3: Substrate Ordination The ordination demonstrates the effects of the varying coral formations, as well as substrates, on the clustering of each transect.
Appendix 4: Live Coral Ordination This graph clusters each transect based on the amount of each live coral formation found within, as well as labels which formations may be drivers for visible patterns of clustering.
Appendix 5: R Script data = read.table("gp_data.csv",sep="\t",header=t) data = data[,2:15] dat.live <- data[,c(1:4,6:7,11,13,14)] names <- as.factor(c("fore1","fore2","fore3","fore4","crest1","crest2","crest3","crest4","ba ck1","back2","back3","back4")) jpeg(width = 800, height=600) plot(hclust(vegdist(data,method="bray"), method="ward"), label=names, main="substrate Cluster", xlab="transect", sub="") plot(hclust(vegdist(dat.live, method="bray"), method="ward"), label=names, main="live Coral Coverage", xlab="transect", sub="") habs <- as.factor(c("fore","fore","fore","fore","crest","crest","crest","crest","back","bac k","back","back")) data.mds <- metamds(data) plot(data.mds,type="n") text(data.mds,display="sites") ordihull(data.mds,habs,col="blue",lwd="2") text(data.mds,display="species",col="red") live.mds <- metamds(dat.live) plot(live.mds,type="n") text(live.mds,display="sites") ordihull(live.mds,habs,col="blue",lwd="2") text(live.mds,display="species",col="red") dev.off()