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An analysis of grain size modification in biogenic carbonate sediments by deposit‐feeding holothurians and echinoids (Eehinodermata) 1
Author(s) -
Hammond L. S.
Publication year - 1981
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1981.26.5.0898
Subject(s) - carbonate , calcium carbonate , reef , geology , aragonite , sediment , dolomite , mineralogy , alkalinity , dissolution , coral reef , oceanography , calcite , environmental chemistry , geochemistry , chemistry , paleontology , organic chemistry
Changes of total alkalinity in seawater during laboratory experiments showed that Holothuria mexicana, Holothuria arenicola, and Isostichopus badionotus dissolve 0.065–0.256% of the calcium carbonate sediments ingested. These and other species of holothurians have acid pH levels in the gut when it is empty. The spatangoid echinoids Meoma ventricosa and Plagiobrissus grandis have alkaline foreguts, even when empty, and do not dissolve calcium carbonate. The process of dissolution by holothurians has insignificant implications for the carbonate mass balance of coral reefs, as only 2% or less of the annual carbonate fixation in reef flats or lagoons may be lost. Sedimentological effects are also inappreciable, as experimental dissolution of 10% of various grades of sediment resulted in only minor changes in their size frequency distributions. The changes were much smaller than the variability of the available sediment and did not conform to the predictions of a simple model, probably due to the nonlinearity of the specific surface area/size relationship of carbonate reef sands. These phenomena, together with the movement of these nonselective deposit feeders through their heterogeneous sedimentary environment while feeding, obviate the utility of sieve analysis for detecting the effects of dissolution.