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The aims of the present study were to identify the trophic roles of shark and batoid species in a tropical marine food web and to examine how ontogenetic dietary changes affect these roles. Elasmobranch species at different stages of maturity (juveniles and adults) are distributed at medium and high trophic levels (3.2–4.2), preying on numerous fish and invertebrates. Nine trophic groups comprising species at different stages of maturity were identified. Considering the maturity stages, elasmobranchs were found in five trophic groups and 37.5% of the regular equivalence nodes in the web. These species had roles as both predator and prey in four trophic levels of the web, participating in most of the roles identified, and are highly redundant in their functions as prey and mesopredators, but not in their role as top predators. The results of the present study suggest that elasmobranchs can be fundamental to the structure and function of marine food webs and highlight the need to include the effect of ontogenetic changes in the diet of these predators in future assessments of their ecological relevance.

Gorgona island, the major insular area in the Colombian Pacific Ocean, is characterized by a remarkably high biological and ecosystem diversity for this area of the world. Coral reefs are well developed and their fish communities have been described using conventional visual surveys. These methods, however, are known to be biased towards detecting larger and more mobile species, tending to ignore small and cryptobenthic species. The two main objectives of this study were to describe the assemblage structure of the cryptobenthic fish fauna and estimate the extent to which this fauna is underestimated by visual surveys.At the beginning and the end of the warm season, we compared the cryptobenthic fish assemblage recorded using visual surveys against the one recorded using "enclosed anesthetic/rotenone samples" on isolated coral colonies (N=54 beginning of warm season; N=17 end of warm season). The crypthobenthic fish fauna associated to coral colonies was characterized by small body sizes and was composed mainly by species of the families Antennaridae, Blennidae, Gobiidae, Labrisomidae, Muraenidae, Serranidae, Scorpaenidae and Syngnathidae. Conventional visual surveys underestimated overall species richness by 28-36% and number of individuals by 16-35%. Noteworthy, four species recorded during this study using "enclosed anesthetic/rotenone samples" were new records for Gorgona island. Although both sampling methods can detect a largely overlapping group of species, the "enclosed anesthetic/ rotenone samples" method was able to detect more individuals and species, including several species that visual surveys fail to detect. Although this study is the first effort to describe the cryptobenthic fish assemblage associated to coral reefs in the Tropical Eastern Pacific, our results suggest that these assemblages are an important component of the reef fish community in the region in terms of biodiversity and functional roles. Rev. Biol. Trop. 62 (Suppl. 1): 359-371. Epub 2014 February 01.Key words: cryptobenthic fishes, coral reefs, sampling methods, visual surveys, enclosed anesthetic/rotenone samples.Non-destructive sampling techniques, such as visual surveys, have been widely used in studies of coral reef fish ecology ever since their introduction by Brock (1954). However, these techniques have several sources of error due to fish mobility, observer experience and transect size (Thompson & Mapstone, 1997;Ackerman & Bellwood, 2000;Palacios & Zapata, 2011). This leads to a sampling bias toward larger and more mobile species, tending to underestimate small and cryptobenthic fishes. Although it has been suggested that consistent errors and biases in the visual estimates might be acceptable in comparative studies (Brock, 1982;Ackerman & Bellwood, 2000;Willis, 2001), underestimating the cryptobenthic component of reef fish communities might have a potentially larger impact on the understanding of their community assembly, trophic ecology and ultimately on their conservation (Mora, Titterson & Myers, 2008). As a ...

The Mejillones Peninsula upwelling system (northern Chile) appears to be a natural laboratory, suitable to test hypotheses concerning variability of copepod growth in nature. In this zone, in January 2000, we collected zooplankton samples inside and outside of an upwelling plume to assess differential responses of copepodid Calanus chilensis to spatial distribution of temperature, chlorophyll a (chl a), current field and dissolved oxygen (DO). We studied variability of prosome length (PL), dry weight (DW), oil sac volume (OSV), ovary development (GI) and a condition index (CI) of females, and PL and OSV of Copepodid Stage C5. The sea temperature ranged between 14 and 20°C in the upper 10 m, whereas chl a varied between 3 and 14 mg m -3. We distinguished 2 zones according to temperature and the current field: a cold retention area coinciding with the upwelling plume, and a warmer highly advective zone, outside the plume. Abundance of most copepodids was associated with cold and chl a-rich waters, and positively correlated to current speeds. DW and CI of females and PL of Stage C5 were negatively correlated to temperature, but not to chl a. Within the cold retention zone, copepodids were more abundant, females and C5 copepodids were larger and heavier, and females had more developed ovaries, but there were no differences in lipid content or CI. We concluded that resulting circulation may act as an efficient mechanism to maintain copepodids within the chl a-rich upwelling center, but this also implies spatial heterogeneity in temperature and food, giving rise to variability in growth and development of copepods, which is then reflected in different-sized individuals in the late stages of development.

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Malpelo Island forms the insular ecoregion of the Colombian Pacific, and is composed by a mosaic of terrestrial ecosystems, and unique coastal and shallow subtidal systems. Considering its insular nature, the oceanographic features of this locality are expected to be related with the physical and chemical dynamics of the Eastern Tropical Pacific (ETP) and be modulated by the regional dynamic of the Colombian Pacific Oceanic Basin (COPC in Spanish). In this work, in situ data was used to describe the thermohaline conditions in the water column in Malpelo Island and identify key water mass during the two contrasting hydro-meteorological periods of the COPC. Furthermore, we analyzed the thermal and haline variability in the COPC and defined the surface geostrophic flow from in situ oceanographic data during the same time in order to evaluate its effect on the oceanographic conditions in the pelagic environment off Malpelo Island.

Objetive: To confirm the presence of Angiostrongylus cantonensis in Lissachatina fulica individuals in Colombia.Methods: 19 individuals of L. fulica were collected in the city of Buenaventura, Valle del Cauca, Colombia. Lung tissue was extracted and two analysis methods were used: visual identification by histological observation, and identification through conventional and real-time PCR. The A. cantonensis detection rate was established taking into account each of the analysis techniques used.Results: Presence of A. cantonensis was confirmed in the lung tissue of L. fulica specimens collected in the city of Buenaventura, Valle del Cauca, Colombia. The detection rate based on visual identification through histological analysis was 89%, whereas it was 95% using conventional PCR, and 100% using real-time PCR.Conclusion: This study confirmed for the first time the presence of A. cantonensis associated with L. fulica specimens in Colombia. Therefore, eosinophilic meningitis could be considered an emerging disease in Colombia.