Global climate change and other anthropogenic stressors have heightened the need to rapidly characterize ecological changes in marine benthic communities across large scales. Digital photography enables rapid collection of survey images to meet this need, but the subsequent image annotation is typically a time consuming, manual task. We investigated the feasibility of using automated point-annotation to expedite cover estimation of the 17 dominant benthic categories from survey-images captured at four Pacific coral reefs. Inter- and intra- annotator variability among six human experts was quantified and compared to semi- and fully- automated annotation methods, which are made available at coralnet.ucsd.edu. Our results indicate high expert agreement for identification of coral genera, but lower agreement for algal functional groups, in particular between turf algae and crustose coralline algae. This indicates the need for unequivocal definitions of algal groups, careful training of multiple annotators, and enhanced imaging technology. Semi-automated annotation, where 50% of the annotation decisions were performed automatically, yielded cover estimate errors comparable to those of the human experts. Furthermore, fully-automated annotation yielded rapid, unbiased cover estimates but with increased variance. These results show that automated annotation can increase spatial coverage and decrease time and financial outlay for image-based reef surveys.

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Georeferenced towed-diver surveys covering more than 100,000 m 2 of benthic habitat and site-specific surveys at 30 sites during 2000-2002 determined distribution and abundance of scleractinian corals at French Frigate Shoals (FFS), Northwestern Hawaiian Islands. Percentage cover of corals was quantified by genus or species in forereef, backreef, and lagoon habitats and at La Perouse Pinnacles using three complementary methods: towed-diver surveys, video transects, and photoquadrats. Habitat-specific colony density and size-class distributions from measurements made within belt transects at fixed sites indicated that three coral genera, Porites, Pocillopora, and Acropora, accounted for more than 93% of total coral cover throughout the atoll, and their relative percentage cover, densities, and size distributions varied according to habitat and geographic location within the atoll. These descriptive data, which provide the most comprehensive overview yet of the scleractinian coral community at FFS, were used to assess the coral reefs' potential for resistance and resilience to selective stressors including bleaching, disease, and Acanthaster outbreaks. They also serve as a baseline for an ecosystem-based, long-term monitoring program with an objective of linking coral community change to other biological and physical factors.

Abstract. Although parrotfish are generally reported to be herbivorous, increasing evidence suggests that some Caribbean species feed on sponges. After observing grazing scars on the barrel sponge, Xestospongia mum, 40 sponges were videotaped on three reefs for 2 0 . 5 h to determine the frequency of parrotfish bites on this species. A total of 10 h of video recording captured 45 bites on normally coloured X. muta and 527 bites on four bleached X. mula by the parrotfish Sparisoma aurofrenarum, Scarus croicensis and Scarus laeniopterus. The viscera (gut and liver) of 55 parrotfish collected from mangrove and reef habitats were digested in nitric acid and analysed for spicule content. The parrotfish collected in the mangroves (mostly Scarus guacamaia and Sparisoma clirysoprerum) had significantly higher masses of spicules in their viscera than did parrotfish collected on the reef (Sparisoma aurofrenarum, Sparisornu viricle, Sparisoma chrpopterurn, Scarus vetula, Scarus coelesrinus and Scarus raeniopterus). The spicules of Geodia gibhrrosa, a chemically undefended sponge that is common in the mangroves but rare in exposed locations on the reef, were abundant in the viscera of parrotfish collected in the mangroves. These results provide further evidence that fish predation has an important effect on the distribution and abundance of Caribbean sponges. ProblemBenthic-feeding marine fish possess excellent mobility and a range of sophisticated sensory capabilities that permit them to detect even well-hidden prey (CHOAT, 1982; VAN BLARICOM, 1982); hence, they are thought to be major determinants of subtidal invertebrate community structure (HIXON, 1983). Nevertheless, there have been relatively few field studies documenting the effects of fish predation on benthic invertebrates. Reviews of research on fish predation have called for better-designed field studies of the foraging behaviour of fish and documentation of the effect on invertebrate communities (HOBSON, 1974; CHOAT, 1982; HORN, 1989; JONES et al., 1991). Specifically, there has been a call for studies that establish the identity of both predator and prey, that incorporate direct field observation, and that use direct measures of the intensity of predation to determine how predation pressure alters the distribution, abundance and structure of prey populations (JONES eta].,

Many marine invertebrate species facing potential extinction have uncertain taxonomies and poorly known demographic and ecological traits. Uncertainties are compounded when potential extinction drivers are climate and ocean changes whose effects on even widespread and abundant species are only partially understood. The U.S. Endangered Species Act mandates conservation management decisions founded on the extinction risk to species based on the best available science at the time of consideration-requiring prompt action rather than awaiting better information. We developed an expert-opinion threat-based approach that entails a structured voting system to assess extinction risk from climate and ocean changes and other threats to 82 coral species for which population status and threat response information was limited. Such methods are urgently needed because constrained budgets and manpower will continue to hinder the availability of desired data for many potentially vulnerable marine species. Significant species-specific information gaps and uncertainties precluded quantitative assessments of habitat loss or population declines and necessitated increased reliance on demographic characteristics and threat vulnerabilities at genus or family levels. Adapting some methods (e.g., a structured voting system) used during other assessments and developing some new approaches (e.g., integrated assessment of threats and demographic characteristics), we rated the importance of threats contributing to coral extinction risk and assessed those threats against population status and trend information to evaluate each species' extinction risk over the 21st century. This qualitative assessment resulted in a ranking with an uncertainty range for each species according to their estimated likelihood of extinction. We offer guidance on approaches for future biological extinction risk assessments, especially in cases of data-limited species likely to be affected by global-scale threats. Incorporación del Cambio Climático y Oceánico en Estudios de Riesgo de Extinción para 82 Especies de Coral.