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Coral reefs provide shoreline protection, biological diversity, fishery harvests, and tourism, all values that stem from the physically-complex coral infrastructure. Stony corals (scleractinians) construct and maintain the reef through deposition of calcium carbonate. Therefore, assessment of coral reefs requires at least some measurement endpoints that reflect the biological and physical condition of stony corals. Most monitoring programs portray coral quantity as live coral cover, which is the two-dimensional proportion of coral surface to sea floor viewed from above (planar view). The absence of the third dimension, however, limits our ability to characterize coral reef value, physiology, health and sustainability. A three-dimensional (3D) approach more realistically characterizes coral structure available as community habitat and, when combined with estimates of live coral tissue, quantifies the amount of living coral available for photosynthesis, growth and reproduction. A rapid coral survey procedure that coupled 3D coral quantification with more traditional survey measurements was developed and tested in the field. The survey procedure relied on only three underwater observations--species identification, colony size, and proportion of live tissue--made on each colony in the transect. These observations generated a variety of metrics, including several based on 3D colony surface area, that are relevant to reef management.

Thalassia testudinum belowground biomass weights, leaf weights, leaf growth rates, areal shoot densities (m (2 ), and leaf C:N:P ratios were compared to a set of biogeochemical parameters to gain information on seagrassÁsediment interactions that may influence seagrass growth. Data were compiled from three surveys conducted in Santa Rosa Sound, located in northwest Florida, at three different meadows in sequential years. Biomass measurements and leaf growth rates decreased between stations along transects from shallow to deeper water. Belowground biomass weights decreased and leaf C:P ratios increased with temperature reflecting a seasonal growth pattern. The T. testudinum parameters were highly correlated with each other. Sulfate reduction rates (at times exceeding 1000 nmol ml (1 day (1 ) were among the highest recorded for seagrass beds with temperature accounting for 79% of the variation. Even though sulfate reduction rates were high, total Fe:reduced S ratios indicated sufficient Fe to account for all reduced S as pyrite. Sediment Fe, C, N, and organic P concentrations increased with sediment depth, whereas inorganic P decreased with depth, suggesting burial of organic P and root uptake of inorganic P. Leaf C:N:P ratios indicated P-limited growth for two surveys. NH 4 ' was detected in water above the sediment surface during some surveys demonstrating T. testudinum meadows at times may serve as sources of inorganic N to the water column. Plant parameters correlated with concentrations of sediment organic C and N, Fe, S, and porewater NH 4 ' . These results highlight the importance of the organic matter and Fe contents of sediments to seagrass growth.