Marine Science Faculty Publications

Anomalous Features Observed on Tests of Live Archaiasine Foraminifers from the Florida Keys, USA

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Historically, Archaias angulatus has been a major contributor to foraminiferal assemblages and sediments in coral-reef environments throughout the Caribbean and tropical Atlantic. A variety of anomalous features were observed in the tests of A. angulatus individuals collected live from the Florida reef tract in 2004 and 2005. Six types of anomalies were documented using scanning electron microscopy: microborings, microbial biofilm, pitted surfaces, dissolution, calcification abnormalities and growth abnormalities. Calcification abnormalities included mineralogical projections, lacy crusts and repair marks. These abnormalities were found among both juvenile and adult A. angulatus, and similar features were also found among Cyclorbiculina compressa and Laevipeneroplis proteus specimens collected live in the same samples.

The implications of these observations are at least twofold. First, in studies of fossil assemblages, damage to tests and changes in test-surface textures should not be assumed to have occurred postmortem and may provide evidence of environmental stressors acting upon living populations. In addition, we speculate that test dissolution in larger miliolid foraminifers when alive can indicate declining carbonate saturation in seawater, which can result locally from salinity changes or increasing benthic respiration rates, as well as globally from rising concentration of atmospheric CO2.

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Journal of Foraminiferal Research, v. 37, issue 3, p. 223-233