Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

The incidence of Vibrio in dermal and internal injuries was evaluated in captive broodstock of spotted sand bass, Paralablax maculatofasciatus. During haemorragic infections the associated bacteria were isolated on thiosulfate-citrate-bile-sucrose agar (TCBS) and on Marine Agar 2216. Isolates were presumptively identified and the pathogenicity was experimentally evaluated. Vibrio alginolyticus, V. cholerae, V. fluvialis, V. parahaemolyticus, V. vulnificus and Vibrio sp. were present in external injuries. Vibrio alginolyticus was consistently predominant in dermal injuries. Clinical signs recorded during the vibriosis outbreaks included hemorrhages and petechiae on body surfaces, which were most severe at the base of the pelvic fins and in the opercular region. Hemorrhages and necrosis were observed on the fins. Affected fish became inactive and anorexic. Internally, hemorrhages in the intestine and a pale liver were observed. During experimentally induced infections, the fish inoculated with 108 cells of the strain VPb-C7 (identified as V. alginolyticus) developed clinical signs and mortality was recorded.

The spatial distribution of the yellowfin tuna (Thunnus albacares) abundance in the Eastern Pacific Ocean was studied from commercial catches by the Mexican tuna-fishing fleet. Concentration profiles were carried out as indicators of a realtionship between catch-per-unit effort (CPUE) and fish abundance for the period from 1992 to 1996. Spatial and temporal resolution "units" were defined by means of a semi-variogram and serial correlation analyses, respectively. The unit resolutions obtained for catch data were 1 × 1 degree (spatial) and monthly (temporal). Catch values were standardized by means of robust regression. Fish resource spatial distribution patterns were identified and estimated catch-values were obtained with Generalized Additive Models. From these estimates, a CPUE time-space matrix CPUE was defined with 60 months and 1029 locations. Nine timespace patterns explained more than 80% of the variability. Individual spatial patterns were analyzed and spatial regions were defined with homogeneous CPUE values. Similarities between the CPUE and the concentration profiles (covered area) suggest that the CPUE-relative abundance relationship is not directly proportional which indicates hyperdepletion processes. Fishery management implications are also discussed in this study.

 Toxicity tests were performed in two amphipod species, Gammarus aequicauda and Microdeutopus gryllotalpa, and three sea urchin species, Arbacia lixula, Paracentrotus lividus and Sphaerechinus granularis. The sensitivity of these marine organisms was evaluated by acute toxicity tests with amphipod juveniles and short chronic embryo-larval tests in sea urchins using the reference toxicants, ammonium chloride (NH4Cl), cadmium chloride (CdCl2), potassium dichromate (K2Cr2O7), sodium dodecylsulfate (C12H25NaO4S) and zinc sulfate (ZnSO4). The acute toxicity tests in amphipods clearly demonstrated the toxicity gradient of these substances. A two-way ANOVA analysis showed that M. gryllotalpa was more sensitive than G. aequicauda to all the reference toxicants studied (P < 0.0001). The tests conducted with sea urchins also pointed to a toxicant gradient and these organisms were seen to be more sensitive than amphipods. The two-way ANOVA analysis showed no significant differences in the IC25 and IC50 values for each reference toxicant in the three sea urchin species. The interaction of sea urchin species and a reference toxicant had no significant effect (two-way ANOVA, P = 0.9), the sensitivity of these Mediterranean species and groups being similar to that of other amphipod and sea urchin species found in the bibliography. The objective of our study is to provide ecotoxicological tools to evaluate the potential toxicity of Mediterranean benthic ecosystems, and in this work, we characterize the toxicity of reference toxicants towards autochthonous species of amphipods and sea urchins.

Degrees of pyritization (DOP) were measured by three different methods in four cores collected in the Gulf of Mexico, close to the outlet of the Coatzacoalcos and Grijalva-Usumacinta rivers. The extractants used for measuring labile Fe, necessary for the calculation of DOP values, were HCl 1N, dithionite and oxalate, with the first two ones being equivalent for measuring DOP, at least in this type of sediments. The data obtained in this work suggest that in deltaic sediments it is possible to find DOP values higher than those measured in the continental shelf of the Gulf of Mexico, with the sediments closer to the outlets of the Coatzacoalcos and Grijalva-Usumacinta rivers showing values that are even higher than those measured in the Mississippi River delta.

The purple snail (Plicopurpura pansa) is a conspicuous rocky-shore species in the tidal zone of the American tropical Pacific. It is considered a potential resource because of the dye it produces. In the 1980s the snail underwent exploitation in the Pacific coast of Mexico. Samples in 12 rocky shores of the Baja California Sur, Jalisco and Oaxaca states, and the Socorro Island were made, finding a sexual ratio near to 1:1, densities ranging from 0.47 to 1.24 snails m–2 and a relation between dye yield and specimens' length. By interviews with the Mixteco people in Oaxaca and milking of the snails over cotton skeins, dye yield was calculated as 2.5 liters of dye per week/fisherman or 2.2 skeins per week/fisherman.

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El artículo no presenta resumen.

El artículo no presenta resumen.

El artículo no presenta resumen.

El artículo no presenta resumen.