Nahant:
The findings suggest that tidal currents account for a large amount of snail movement around the intertidal. This is strongly represented with 95% of individuals moving farther than 5m from their origin over only 7 tidal cycles. With an average individual movement of ~20-25 cm per 10 days (Hamilton 2004) Littorina sp. is obviously at the will of the tide as far as magnitude of movement is concerned. This has implications for the distribution of Littorina around the intertidal. Given the illustrated effect that the tide can change an individual snails position at least 5m in 3 days at the most, would this cause a concentration of snails at points in the intertidal that are least sheltered from the tide? If this is true, the dynamic of the zonation of the intertidal could be changed drastically over time. The concentration of a large percentage of the Littorina population in a smaller area would change the ecological features of that area. More algae would be grazed and destroyed from the snails in this portion of the intertidal than anywhere else. It would also attract the snail predators to this area of a virtual Littorina buffet table. Activity in the intertidal as a whole would be centered around this area until one of the species is completely removed which would in turn alter the entire landscape.
As with any study there were limitations to the experiment. The nail polish used to tag the snails was “waterproof” but over numerous days of wetting and drying the efficacy of this claim could be suspect. There is a large amount of algae, namely Ascophyllum and Fucus species at this site which lends the idea that some tagged individuals could have been missed within the 5m zone. With these considerations in mind the finding of any marked snails was a bit of a surprise. The difficulty if tagging and recapturing such a small species in a large environment as Nahant makes more detailed research difficult but a tide by tide survey of a replicate of this study could shed more light on the movements of Littorina snails.
Bermuda:
No difference was found between the sites on the north and south shore of Bermuda in terms of species diversity of corals. This is not to say that there aren’t differences in the sites themselves, the environmental differences have simply not translated into the reduction or proliferation of coral species. Studies to examine water qualities such as sedimentation, nitrate levels, algae growth should all be conducted. Changes in any or all of these would impact the corals of Bermuda. These findings are by no means all-encompassing of the reefs of Bermuda as a whole, this is a small sample that does include the vast majority of coral species of Bermuda. The health of the reefs is not simply measured by the biodiversity of coral species, the health of the corals and other organisms that depend on the reefs is a more vital consideration. Bermuda appears to be populated by heartier corals to begin with, slight changes in environment may not necessarily impact them. Corals such as those in the genus Acropora are more sensitive to their conditions. More data is needed as to the water quality changes of the north shore in order to get a larger view on the possible threat to corals that the development of Bermuda has instituted.