Bleaching in a Reef-dwelling Foraminifer, \u3cem\u3eAmphistegina gibbosa\u3c/em\u3e

In field collections from reefs off Key Largo, Florida, in September 199 1, 80% of living adolescent and adult Amphistegina gibbosa, a larger foraminifer that hosts diatom endosymbionts, ex- hibited either mottling or extensive symbiont-color loss. Many Cnidaria in the vicinity also were bleached. Comparison of September and Novem- ber abundance and size-frequency data indicated high mortality, particularly in bleached size classes. Although the cause of bleaching in A. gibbosa has yet to be determined, laboratory observations in- dicate that this species may be vulnerable to ele- vated ultraviolet radiation. In 199 1, volcanic aero- sols globally reduced visible and infrared radiation and promoted stratospheric ozone depletion, thereby increasing UV radiation reaching the sea surface

Foraminifera as Bioindicators in Coral Reef Assessment and Monitoring: the Foram Index

Coral reef communities are threatened worldwide. Resource managers urgently need indicators of the biological condition of reef environments that can relate data acquired through remote-sensing, water-quality and benthic-community monitoring to stress responses in reef organisms. The “FORAM” (Foraminifera in Reef Assessment and Monitoring) Index (FI) is based on 30 years of research on reef sediments and reef-dwelling larger foraminifers. These shelled protists are ideal indicator organisms because: Foraminifers are widely used as environmental and paleoenvironmental indicators in many contexts; Reef-building, zooxanthellate corals and foraminifers with algal symbionts have similar water-quality requirements; The relatively short life spans of foraminifers as compared with long-lived colonial corals facilitate differentiation between long-term water-quality decline and episodic stress events; Foraminifers are relatively small and abundant, permitting statistically significant sample sizes to be collected quickly and relatively inexpensively, ideally as a component of comprehensive monitoring programs; and Collection of foraminifers has minimal impact on reef resources. USEPA guidelines for ecological indicators are used to evaluate the FI. Data required are foraminiferal assemblages from surface sediments of reef-associated environments. The FI provides resource managers with a simple procedure for determining the suitability of benthic environments for communities dominated by algal symbiotic organisms. The FI can be applied independently, or incorporated into existing or planned monitoring efforts. The simple calculations require limited computer capabilities and therefore can be applied readily to reef-associated environments worldwide. In addition, the foraminiferal shells collected can be subjected to morphometric and geochemical analyses in areas of suspected heavy-metal pollution, and the data sets for the index can be used with other monitoring data in detailed multidimensional assessments