Document Type

Article

Comments

Published in: Limnology and Oceanography, v. 42, 1997.

Abstract

An in situ survey of deep reef environments (20 and 30 m) was conducted to determine the degree to which the community structure of live reef coral assemblages was faithfully represented in the adjacent death assemblages accumulating on the sea floor. Relative abundance of species was significantly different between life and death assemblages, and zonation patterns (in species relative abundance, coral growth form, and diversity) present in the life assemblages showed both similarities and differences to those found in the death assemblages. The difference in species distribution patterns between life and death assemblages is shown by a striking growth form bias in the death assemblage: species with massive growth forms are underrepresented in the death assemblages in both environments, whereas branching, encursting, and plate growth forms are overrepresented in the death assemblages. Several factors may be involved in the life and death assemblage differences: greater degrees of time averaging than in previously studied reef settings, changes in the life assemblage such that death assemblages record previous life assemblages more faithfully than present ones, and undersampling of massive corals in death assemblages. Comparison of species richness and the Shannon‐Wiener index of diversity between life and death assemblages produced unexpected results. In general, death assemblages showed higher diversity than did life assemblages, more in accordance with previous studies of shelly molluscan faunas of temperature and tropical level‐bottom marine communities than with those of shallow‐water coral reef communities. Because our results differ from previous studies of community preservation in coral reefs, we recommend that paleoecological studies of aquatic ecosystems be accompanied by preservational assemblages from the same or similar environments. Our results point to the subtleties involved in interpreting coral death assemblages and suggest that these assemblages may contain as much or more information on recent changes in the living reef as they do on the future composition of the fossil reef assemblages.

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