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Copyright of Conservation Biology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Conservation Biology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Coastal ecosystems and the livelihoods they support are threatened by stressors acting at global and local scales. Here we used the data produced by the Caribbean Coastal Marine Productivity program (CARICOMP), the longest, largest monitoring program in the wider Caribbean, to evidence local-scale (decreases in water quality) and global-scale (increases in temperature) stressors across the basin. Trend analyses showed that visibility decreased at 42% of the stations, indicating that local-scale chronic stressors are widespread. On the other hand, only 18% of the stations showed increases in water temperature that would be expected from global warming, partially reflecting the limits in detecting trends due to inherent natural variability of temperature data. Decreases in visibility were associated with increased human density. However, this link can be decoupled by environmental factors, with conditions that increase the flush of water, dampening the effects of human influence. Besides documenting environmental stressors throughout the basin, our results can be used to inform future monitoring programs, if the desire is to identify stations that provide early warning signals of anthropogenic impacts. All CARICOMP environmental data are now available, providing an invaluable baseline that can be used to strengthen research, conservation, and management of coastal ecosystems in the Caribbean basin. [ABSTRACT FROM AUTHOR]

Abstract: Heavy rainfall caused a severe disturbance on the Thalassia testudinum meadows at Morrocoy National Park in December 1999, affecting its associated infauna and inducing responses to stress in opportunistic polychaetes belonging to the Spionidae Family. The changes were evaluated at four seagrass beds, examining the structure and species composition of the Spionid macrofauna over eight samplings: four prior and four after the disturbance. Immediately after the heavy rainfall the Spionids showed transient changes, expressed as large increases of species density and richness, reaching values of 875 individuals m−2 (against the usual 20 individuals m−2) and 7 species (against the previous 1–3 species) during February 2000. These abundance pulses were represented by selected species at each location. Opportunistic species, having limited dispersion (Streblospio gynobranchiata and polydorids) were commonly found in continentally-influenced locations whereas species having dispersal mechanisms were commonly found in stations under oceanic influence (species of the Genus Prionospio). Likewise, the observed recovery patterns indicate different rhythms: while the oceanic communities showed a fast recovery, the continentally ones returned to their original states slowly. Hence, the patterns observed in the benthic polychaete communities associated with the T. testudinum beds from Morrocoy N.P. clearly indicate that the recolonization processes, succession dynamics and recovery time depend on the spatial scale of disturbance, the life history of species involved and the particular conditions of the habitat. [Copyright &y& Elsevier]

Notionally herbivorous fishes maintains a critical ecosystem function on coral reefs by grazing algae and maintaining highly productive algal turf assemblages. Current paradigms implicate habitat complexity, predation, and primary productivity as major drivers of the distribution and abundance of herbivorous fish, yet little is known about the relative contribution of these factors. Here, we compare bottom‐up and top‐down drivers of notional herbivore assemblages across an environmental gradient of wave exposure in the Palau archipelago. We surveyed herbivore assemblages at reef slopes (6–9 m) across 18 sites, and quantified proxies of top‐down control (predator biomass, habitat complexity) and bottom‐up drivers (net primary production, nutrients) at each site. Despite substantial variability in herbivore biomass throughout the archipelago (6–65 g/m2), general additive models indicate that neither top‐down nor bottom‐up drivers significantly predicted biomass or density of herbivores among sites. In contrast to expectations, herbivore biomass was highest at sites with high predator biomass, low structural complexity, and low benthic productivity. Rather, the highest biomass of herbivores was associated with shallow, tidally emergent, productive reef flats located adjacent to steep vertical walls ("drop‐offs"). The emergent nature of this neighboring habitat precluded occupation by territorial fishes and multiple species of herbivores were observed to make foraging runs into this habitat once tidally inundated. We hypothesize that this habitat configuration provides an important cross‐habitat resource subsidy. Multivariate ordination and permutation of herbivore communities revealed strong evidence for biogeographic partitioning throughout the archipelago (western, southwestern, inner eastern, and outer eastern clusters), contributing to an emerging picture that the habitat heterogeneity of seascapes can overwhelm the effects of conventional top‐down and bottom‐up structuring of herbivory on coral reefs. [ABSTRACT FROM AUTHOR]