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Bioassessment Tools for Stony Corals: Field Testing of Monitoring Protocols in the US Virgin Islands (St. Croix)
Citation:
Fore, L., W. S. FISHER, AND W. DAVIS. Bioassessment Tools for Stony Corals: Field Testing of Monitoring Protocols in the US Virgin Islands (St. Croix). U.S. Environmental Protection Agency, Washington, DC, EPA/260/R-06/004, 2006.
Impact/Purpose:
Coral reef communities surrounding the US Virgin Islands (USVI) represent a valuable economic and aesthetic resource for visitors and residents (USVI DEP & DPNR, 2004). The government of USVI recognizes their value and supports a variety of coral reef monitoring efforts (Nemeth et al., 2004).Along with rivers, streams, lakes and estuaries, the Federal Clean Water Act (CWA, 1972) provides a regulatory framework for the assessment, management and protection of near-shore water resources, including coral reefs. Both the CWA and the US Virgin Islands Territorial Water Pollution Control Act (1972) outline regulations for protection of surface waters and the biological assemblages they support. Two programs specifically rely on biological monitoring data in coastal marine areas: the 301(h) waiver program and the 403(c) ocean discharger program. The waiver program allows marine dischargers to defer secondary treatment if they can show the discharge does not affect biological communities. The ocean discharger program requires all dischargers to marine waters to provide an assessment of the biological community in the area of the discharge (Jameson et al., 1998).
Description:
Survey protocols for assessing coral reef condition were field tested at 61 reef stations in St. Croix, US Virgin Islands (USVI) during 2006. Three observations for stony corals were recorded: species, size, and percent live tissue. Stony corals were selected because they are primary producers of the reef environment, they provide structure and habitat for other reef organisms, and they support tourism and fisheries. Dive teams fromthe US Environmental Protection Agency and the USVI Division of Environmental Protection (DEP) collected physical measurements and recorded the condition of coral colonies found within a radial belt transect. Duplicate samples by different dive teams on the same reef station indicated that the protocol was repeatable. Candidate coral metrics were tested against a gradient of human disturbance at three locations. Candidate coral metrics from four categories were tested: species abundance and composition, physical stature, biological condition, and community structure. Human disturbance gradients were based on visual observations and narrative descriptions of land use on shore. No quantitative or chemical measures of water quality were collected. For the most intensely disturbed area, 4 metrics were highly correlated with distance from an industrial point source: total surface area of coral, total live surface area, taxa richness, and average colony size. For the other two gradients, changes in metric values were not associated with human influence, possibly because disturbance in these areas was minimal Alternatively, the metrics tested here may not be capable of detecting subtle changes in reef condition. Many metrics were highly correlated with depth, even when the range of depth was only 20–40 ft. A statistical power analysis determined that a survey area of 50 m2 was no more precise than a survey area half that size. Coral metrics derived from this protocol had adequate precision to detect a reasonable level of change in coral reef condition that would be protective of the resource.
URLs/Downloads:
Bioassessment Tools for Stony Corals: Field Testing of Monitoring Protocols in the US Virgin Islands (St. Croix)