The Importance of rate of Biomass Accumulation in early Successional stages of Benthic Communities to the Survival of Coral Recruits

Birkeland, Charles

Although hermatypic coral recruits grow faster on the upper surfaces of artificial substrata on coral reefs, survival is greater in the shade on vertical and under surfaces. Growth of recruits is faster in shallow waters but survival increases with depth, at least to 20m, as the light decreases. Adult corals can survive and grow in cool nutrient-rich waters, but survival of recruits is more successful in nutrient-poor waters. Nutrients and light are beneficial to coral growth, but faster-growing fouling organisms respond more directly to a rich supply of nutrients and light. As levels of light and nutrient input decrease, the rate of biomass accumulation of the benthic community decreases, and hermatypic corals have a greater chance of reaching a refuge in size from being overgrown. Between geographic locations, the difference in rate of biomass accumulation at comparable depths is influenced by nutrient input. At a given locality, the rate of biomass accumulation of algae is related to light which decreases with shading and depth. Fish grazing on the benthic community is beneficial to the survival of coral recruits. Caribbean fish will avoid feeding on corals as small as 2.5 mm maximum diameter. Species with r-selected characteristics are not just "opportunists" that depend on disturbance to release resources from tight competitive situations. Under conditions of high nutrient input from outside sources, r-selected species can be the perpetually superior competitors for space, preventing K-selected species from establishing themselves and gaining a refuge in size.

The Importance of rate of Biomass Accumulation in early Successional stages of Benthic Communities to the Survival of Coral Recruits

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