Project 2: Gaya Island

Finding Nemo: A Voyage of Discovery of the Association between Anemonefish and Anemone Species

Alan Chiu, Cindy Liu, Ayu Nurinsiyah, and Anna Ruman

The symbioses between host anemones and anemonefish species, although often simplified and romanticized by popular media, demand additional field observation in order to expand scientific understanding of these complex relationships. The association between anemones and anemonefish has been frequently noted in the literature, but no studies have yet been conducted to examine the species-specificity of this symbiosis. Our study examined 3 common anemonefish species and 4 common anemone species native to Malohom Bay, Pulau Gaya, Borneo, Malaysia. Randomized 5 m wide transects perpendicular to the shoreline were surveyed, and 27 anemone and anemonefish species pairings were recorded. Pearson's Chi-squared tests for count data were performed on fish species vs. anemone species and fish species vs. relative anemone tentacle length (classed in 3 sizes: short, medium, and long). The p-values for both tests were significant at the 99% confidence level (p < 0.01 for both comparisons), indicating that there is highly significant species-specificity between anemone and anemonefish species and between anemone tentacle length and anemonefish species. In addition, calculation of the Standardised Specialization Index (d') reveals perfect specialization of the False clownfish (d'=1.0) and the Hadden's anemone (d'=1.00) to eachother; False clownfish were found in association only with Hadden's anemones and vice versa. Although all anemonefish species as well as the Hadden's and Corkscrew anemones show a degree of specialization (d'>0.5), the Bulb-tentacled and Gigantic anemones show generalist qualities based on their low d' values (d'= 0.382, d'=0.043) due to the their association primarily with the dominant anemonefish species, the Spinecheek. Lastly, calculation of the nestedness temperature of the anemonefish and anemone species association matrix yields an intermediate temperature of 30.3, indicating degrees of both nestedness order and randomness of the mutualistic system. Observation of these close associations between anemonefish and anemone species has important ramifications regarding the vulnerability of these symbiotic partnerships to reef degradation; further research could be conducted to determine whether these species-specific relationships result from adaptations of the physiology or the morphology of the fish and/or anemones.

Random distribution pattern of goby fish (Family: Gobiidae) in Maloham Bay, Gaya Island, Sabah

Chong Kwek Yan, Dwi Susanto, Katherine O'Leary, Muhamad Ikhwan Idris, and Wulan Pusparini

Spatial distribution pattern of an organism can reveal ecological underpinnings such as availability of resources, preferred habitats, or hint at territorial behavior. The spatial distribution of goby's holes on large, relatively homogenous stretches of sandy substrate in the littoral zone is an ideal case study to look on this matter. Two belt transects of 1m width by 25m in length were laid out on the sandy littoral zone of Maloham Bay (N 06 1.187, E 116 2.865), on an island of the coast of Sabah, Malaysia. The number of goby's holes within each 1m by 1m square plot along the transects were counted and a mean-variance index of the data was computed. The score of 1.11 suggests that the spatial distribution can largely be explained by random chance of occurrence (~1.0). An overlay of the count histogram on a Poisson distribution curve (lambda = mean number of holes) showed a good fit. Although these data are insufficient to conclude that gobies are either territorial or gregarious, it was observed on several occasions the presence of multiple gobies occupying a single hole, indicating a willingness to share a common space. Whether this is a normal occurrence or due to some unknown factor (group territorial behavior, breeding season, particular different species etc.) it does show that for the species of gobies we observed, they are not perpetually solitary within each hole.

Coral Complexity and Fish Diversity

Benjamin Gutierrez and Shreekant Deodhar

We studied whether physical complexity of corals affects fish species richness at Gaya Island, Borneo, Malaysia. Two observers counted fish morphotypes for fish that aggregated at single heads of coral, which were either branching, digitate, or massive coral. There were statistically significant differences in fish richness between the branching coral and the other two types (Kruskal-Wallis, p < 0.05 and two Wilcoxons p < 0.05). We believe that these differences arise because branching corals offer a more intricate shelter for protection from predators and for more niches. However, during the study we realized the importance of algae on corals in attracting fish for feeding; a more accurate study would control for algal cover.

Anemonefish Size and Vigilance

Karl Kmiecik, Greg Parker, and Will Skinner

Anemone fish are are well known to be aggressive defenders of their host anemones. This study examines whether anemone fish size, species, and presence of mates or young is related to the level of this vigilance behavior. A total of 19 anemones containing anemone fish were sampled in the back reef and reef crest of Malohom Bay, Pulau Gaya, Malaysia. Three species were found: 11 Spinecheek Anemone Fish (Premnas biaculeatus), four False Clown Fish (Amphiprion ocellaris), and four Clark's Anemone Fish (Amphiprion clarkii). Aggressiveness of vigilance behavior was measured by the distance at which the anemone fish would first charge at a diver swimming directly toward the host anemone. Linear regression analysis of initial charge distance as a function of anemone fish size shows a significant positive correlation (p-value = 0.0452). Surprisingly, fish species did not appear to be a significant factor affecting charge distance in this data set (p-value = 0.2109). The data suggest that fish size is the most important factor in determining anemone fish aggressiveness, regardless of species, number of fish in the anemone, and anemone location. However, low sample quantity of A. clarkii and A. ocellaris suggests that more comprehensive study may be necessary to strengthen conclusions about aggressiveness between species and elucidate other possible confounding effects such as the presence of eggs.

The Effect of Trash on Bornean Coastal Mangrove Communities

Noor M. R. Beckwith, Justine S. Chow, and Chea Yiing Ling

Coastal mangrove thickets are unique and critically important ecological entities; their stilted roots provide habitat and nurseries for many specialized marine species. These stilted roots also have the unfortunate tendency of trapping drifting trash from human activities. Because of the thickets' great significance, we wanted to determine if the communities they foster exhibit any effects from the man-created trash. On Pulau Gaya, Sabah, Malaysia, three discrete mangrove (Rhizophora apiculata) thickets were selected and subdivided into 2 x 2 m blocks. Two of these blocks within each thicket were randomly selected and surveyed for species richness and abundance of fish, snails, and crabs. Trash items were also collected and recorded. Total species richness (number of fish, snail, and crab species) was found to be significantly positively correlated with the number of trash items in the area, using a simple linear model (p = 0.0235). There was no significant correlation between the species abundance and the number of trash items by using the same analysis. A possible explanation for this somewhat unexpected result is that some items of trash may offer new food sources or new microhabitats for marine animals. Another reason could be the underlying factor of currents; places where trash has a tendency of building up may also have the tendency of accumulating more food sources and thus increased marine animal populations. However, given our limited sample size and composition data, other tests such as GLM and Wilcoxon Test turned out to be insignificant; thus it is too early to make any more specific conclusions about human impact on the communities within mangrove thickets. An area for future research regarding coastal mangrove communities and anthropogenic impact should take into consideration marine currents, species turnover, root complexity, and tidal inundation cycles.

Clustering Behavior of Black Urchins

Wijayathilaka Nayana, Eni Hidayati, Nur Edna Hasreena Ahlun, Jovina Jowinis, and Alessandra Markos

The nocturnal and clustering behavior of black sea urchin (Diadema setosum) are believed to be defense mechanisms for avoiding fish predators. We studied the colony size of Diadema setosum between two reef habitats at Malohom Bay, Pulau Gaya, Sabah. A line transect of 20 m by 5 m along the shore line with two replicates was laid on fore reef and crest, and the number of sea urchin per colony was recorded. The results shows that there is a significant bigger aggregation of Diadema setosum in the fore reef zone than the crest zone. This behavior probably acts as a defense mechanism during sleeping to avoid predators. When they form a colony and stay close to each other, their spikes act like a fortress protecting their delicate parts. Colonization makes it harder for predators to flip them. Aside from predators threat, the bigger size in the fore reef probably because the fore reef provides more space for aggregations.