Background: The Bocas del Toro Archipelago is located off the Caribbean coast of Panama. Until now, only 19 species of heterobranch sea slugs have been formally reported from this area; this number constitutes a fraction of total diversity in the Caribbean region. Results: Based on newly conducted fieldwork, we increase the number of recorded heterobranch sea slug species in Bocas del Toro to 82. Descriptive information for each species is provided, including taxonomic and/or ecological notes for most taxa. The collecting effort is also described and compared with that of other field expeditions in the Caribbean and the tropical Eastern Pacific. Conclusions: This increase in known diversity strongly suggests that the distribution of species within the Caribbean is still poorly known and species ranges may need to be modified as more surveys are conducted.
Abstract:The molluscan fauna of Isla del Coco has recently been well documented, but the heterobranch sea slugs, traditionally called "opisthobranchs", remain poorly known. We report 13 new records, increasing the total to 40 species. Of the 13 newly discovered species, the following species had not been previously recorded along the Pacific Costa Rican mainland: Berthella californica (Dall, 1900), Peltodoris rubra (Bergh, 1905), Dendrodoris albobrunnea Allan, 1933,
<p>The intertidal rocky shore of Bahía Panama, within Bahía Culebra in the North Pacific coast of Costa Rica, was sampled to study the biodiversity and the spatial patterns (three sites with differences in wave exposure, and five strata, from low to high tide levels) and temporal variation (a single date in 2007 and 2013) in different microhabitats (over and under rock surface, and crevices). The epibenthic organisms were sampled with quadrats of 25 x 25 cm in each stratum, and cryptic fauna was accounted by both visual census and manual collecting. The general pattern of vertical zonation of organisms at each site showed an increase in variety toward the infralittoral level, as well as in the composition of assemblages or partially in identity of taxa in each stratum. The sheltered section of the rocky coast, with shallow sand bottom (< 1 m), low wave action and greater sedimentation rate, had lower diversity, cover and abundance that increased towards the wave-exposed section, with more abrupt slope in the edge of rocky platform, lower turbidity, and deeper sand bottom (2-3 m). The horizontal change was more evident in epibenthic organisms, followed by the under rock surface inhabitants and finally in crevices. For the epibenthic organisms, a temporal change in assemblages (cover and abundance) was found between the 2007 and 2013, at each site and level (possibly by seasonal upwelling influence), but the spatial structure (vertical and horizontal) of the rocky shore seems the main cause of change in the composition of species. The spatial pattern of change in the biota (sheltered to exposed gradient) could be expected in similar shores of the Central American Pacific. Finally, the 157 species found (16 autotrophic taxa, 22 fishes, and 119 invertebrates) indicate the high biodiversity of this habitat in the tropics, and the importance of their conservation. Rev. Biol. Trop. 62 (Suppl. 4): 85-97. Epub 2014 Diciembre 01.</p>
Caribbean coral reefs started to deteriorate before systematic monitoring began and so questions remain about how reefs have changed since human impact and if they have transitioned into functionally ‘novel’ states. To explore these questions, we mapped and bulk-sampled several hectares of mid-Holocene reefs in Caribbean Panama and the Dominican Republic and compared the composition and ecological function of these pre-human impact reefs to nearby modern reefs. We quantified the remains of all major reef groups, but focus here on molluscs, corals, and fishes. Filter feeding molluscs are twice as abundant relative to other feeding modes on modern reefs, commensurate with eutrophication from land use changes. At the same time, large herbivorous gastropods declined significantly in size due to millennia of human selective harvesting. We observed the well-documented loss of Acroporid corals and a functional shift in coral communities towards weedier, slower growing, and brooding species. Some modern coral communities appear to retain some historical functions, and isolated Acropora refugia do persist, but the corals in them are less robust than those in the mid-Holocene, questioning their functional resilience to future change. Reef fish otolith assemblages suggest an 80% decline in non-harvested fish and a relative increase in planktotrophy—patterns best explained by the loss of coral structure and eutrophication. Counterintuitively, otolith sizes suggest that non-harvested fish are larger than they were in the past, a result that suggests lower mortality rates from reduced predation due to a loss of predators. This conclusion is supported by the estimated 71% decline in shark abundances and 400% increase in evidence of damselfish algal-gardening on modern reefs. These examples illustrate how both bottom-up and top-down processes have reshaped the structure, trophic interactions and ecosystem functions of Caribbean reefscapes.
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