Ecology of Atlantic Shores Erin Miller, 2008

Home -------------------------- Nahant -------------------------- Narragansett Bay: Introduction Water Quality Methods Observations Results Discussion -------------------------- Bermuda: Introduction Water Quality Coral Disease Aspergillosis Hypothesis and Methods Results Discussion -------------------------- Conclusions -------------------------- References

Bermuda Discussion The data obtained was not consistent with predictions that there may be a relationship between the proportion of diseased colonies and the proportion of colonies lacking zooxanthellae. The locations sampled may not have had high environmental stress (supported by the water quality results), and therefore there may not be a relationship between the loss of zooxanthellae and infection with Aspergillosis. Temperature is the main stressor that limits photosynthesis in zooxanthellae and thereby decreases the energy available to a sea fan, and my results did not indicate a significant difference in temperature across the sample locations.  Therefore, the reason for the incidence of Aspergillosis in sea fans in the sample sites may not be due to environmental stress across all areas, but instead specific weaknesses in individual sea fans at each given site. The strengh of the disease in each given site may simply be high enough to infect sea fans that are not stressed. Furthermore, although environmental stress both limits zooxanthellae growth and decreases resistance to disease, these two may not have direct a relationship.  I also predicted that areas with higher densities of G. ventalina would have higher incidence of Aspergillosis, which was not supported in my results. It is possible that this is due to low sample sizes taken in areas with low disease incidence. Since these predictions are supported in the literature, it is likely that I would have obtained similar results if I had taken larger samples in areas with varying densities of G. ventalina conlonies and higher incidence of Aspergillosis. Dube et al. used 25x2m transects; much larger than my sample areas (19). There was little difference in water quality results between the four locations tested, so it can not be determined if G. ventalina colonies are affected by environmental stress or nutrient inputs. It can also be determined by the water quality data that the locations sampled are not currently threatened by marine pollution. However, my water quality tests were not extensive, and the threat of pollution on marine ecosystems of Bermuda may be better determined by BIOS's research. Another suggestion to improve the quality of the results would be to measure the surface area of diseased and non-diseased sea fans. Therefore, one could determine if sea fan surface area makes colonies more prone to infection along with sea fan density. This was supported by Dube et al., stating that larger colonies are more likely to be infected due to greater surface area.