Conclusion

Temperature, salinity, sigma-theta, aragonite saturation, dissolved oxygen, nutrients, current velocity and food supply have been identified as the most important drivers of cold-water coral habitat suitability by this blog. However stability of these parameters under optimal conditions are the most important factor when geological time records are considered. The cosmopolitan occurrence of L. pertusa is restricted to the present period, the Holocene, which is considered relatively stable (Wienberg et al., 2009). Over short temporal scales, L. pertusa seem tolerant of fluctuations of many variables, often caused by oceanographic processes, but on a larger temporal scale, parameters outside the normal range appear to be severely detrimental.

No conclusions can be made as to what is the most important environmental factor. This is due to the lack of research, furthermore much data was collected from laboratory experiments where the organisms get a regular large food input which may help them cope with adverse conditions and is not representative of the natural conditions. Realistically, all the parameters discussed are as important as each other as L. pertusa reefs do not occur often outside the defined range.

To summarise, on large scales, we suggest sigma-theta is the most important driver of L. pertusa distribution. If larval supply is controlled by the density layer then this is essential for genetic flow and appears to be the defining factor for the difference between reefs and solitary patches of L. pertusa. Aragonite appears to be another significant driver, but lack of L. pertusa in the pacific may not be solely put down to unsaturated water. L. pertusa is found in variable temperatures, salinities, and dissolved oxygen and nutrient concentrations, so whilst important drivers, they are less so than water density and aragonite saturation. On small spatial scales local hydrodynamic processes appear to be the most important factor. With good food supply L. pertusa has shown forms of resistance to ocean acidification and is important to meet metabolic rate increases induced by increased temperature and low dissolved oxygen concentration. Looking to the future it can be predicted that aragonite may become the most influential limiting factor, though changes in the past to many of the variables discussed may have severe consequences, possibly resulting in local or widespread extinctions.

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