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

Larval size is considered as an important variable to understand the changes in larval development and identification of a suitable environment for larval growth and survivor. Larvae of the Pacific mackerel (Scomber japonicus) have a slow growth during the early stages of development (6-8 mm SL); subsequently, the growth rate increases, but the development depends mainly on the temperature and food. The aim of this study was to identify the areas and seasons favorable for larval development of S. japonicus, in relation to the sea surface temperature and the zooplankton biomass, off the west coast of the Baja California Peninsula (~25°-32°N) from 2006 to 2010. Larvae of the Pacific mackerel showed the greatest amplitude in their spatial distribution during spring, but with greater restricted abundance compared to Punta Eugenia (~28°N) during summer. Changes in its distribution were influenced by geostrophic flow and thermal variability. Linear regression analysis allowed to identify areas favorable for larvae development, with a lower development in spring, related to a narrow range of temperatures and levels of comparatively low zooplankton biomass. In contrast, during summer the largest increase in body height () was related to a wide range of temperatures, while its low variability (standard error) coincided with high levels of zooplankton biomass. It is considered that thermal conditions and food availability, favor an optimum larval development, particularly during the summer season.

In order to understand the anatomical organization of the digestive system of the flounders Syacium papillosum and Syacium gunteri, adult specimens from both sexes for the two species were analysed. By means of dissections of the visceral skeleton, visceral musculature, and the digestive tract, the morphology of the digestive system of the species was found to be affected by the extreme flattening of the body, the asymmetry of the cephalic region, and the reduction in volume of the visceral cavity. The flattening of the cephalic region implies a certain degree of vertical expansion of the visceral skeleton and musculature. The asymmetry was more pronounced in the palatine bones series, mandibles, and in the adductor mandibulae and intermandibularis muscles. The reduction in size of the visceral cavity, due to the forward extension of the anal fin, also implies that the location of the posterior intestine and anus is advanced. The most noticeable characters of the digestive tract were the great size of the stomach, the presence of 4 pyloric caeca, and the intestinal valve. The liver was located on the left side of the visceral cavity. The sharpness of the mandibular and branchial teeth, the great development of the adductor mandibulae muscles and retractor dorsalis muscles, the great size of the stomach and the intestinal ratio correspond to species of carnivorous habits. The anatomical characters that differentiate the digestive system of the species under study are the presence of a small stomach caeca, the greater length of the inferior pyloric caeca and 8 gill rakers in the inferior branch of the first branchial arch in S. papillosum, and the absence of the stomach caeca, the shorter length of the inferior pyloric caeca and 7 gill rakers in the inferior branch of the first branchial arch in S. gunteri. The comparison of the digestive system of both species with other Paralichthyidae and a Bothidae, allows the recognition of the same morphological pattern. The digestive system of Achirus lineatus (Achiridae) markedly differs from that of the Paralichthyidae and Bothidae by the extravisceral character of 2 intestinal loops, while the one from Symphurus civitatium (Cynoglossidae) differs by the presence of the suspension of the esophagus from 3 precaudal vertebrae.

The functional role of coral-associated bacteria and their contribution to coral health is still largely unknown. The first necessary step to address this gap in the knowledge is based on characterization of the microbial assemblage of the coral and the species-specific, temporal and spatial variation in its diversity. Branched corals (e.g., genus Pocillopora), are the main builders of coral reefs worldwide. This study evaluated the bacteria associated with the mucus and tissues of Pocillopora damicornis and Pocillopora verrucosa, as well as that of the seawater and surrounding sediments, in 6 sites of the Mexican Central Pacific during summer and winter seasons. The molecular techniques DGGE and RFLP were used with the 16S rDNA to assess the most abundant bacterial OTUs. The relationships between the bacterial-coral assemblage and environmental and spatial variables of the reef surroundings were also evaluated, using the multivariate analyses. Twenty different Operational Taxonomic Units (OTU) were obtained, with the highest number presented by the sediments. Specificity of bacterial groups was found for each coral species, as well as between the tissue and mucus of each species. The results showed that the bacterial dominant groups were similar between seasons, but these showed significant spatial variations among substrates within sites, as well as per substrate across all sites. The environmental variables that explained the variation of the dominant bacterial groups in corals and sea water were the coverages of fleshy macroalgae, live coral and sponge. In contrast, variation in the sediments was explained by the coverages of sand, rubble and rock.

The pelagic larval stage of the common Caribbean lobster Panulirus argus, takes place during 6-8 months in ocean waters away of shelf. Predicting larval recruitment and identify the areas of arrival and settlement, and assess the quality of their breeding habitats, have been permanent necessity in studies of population dynamics of this fishery resource. The purpose of this work was to determine the potential percentage of self-recruitment larvae to the southwest Cuba shelf, and to identify the main areas of arrival or settlement of puerulus. The simulation, using particles released in a major period of spawning and larval recruitment, using the numerical model LADIM developed in the Institute of Marine Research in Norway. The percentage of selfrecruited larvae was 33.8%. The zones of arrival and greater density of particles, according to modeling, coincided with the areas that by in situ studies have shown greater settlement of puerulus and have been classified as natural nurseries of post-larvae and juveniles. This suggests that hydrodynamics ocean-shelf connectivity in the southwest region of Cuba, it is decisive to the success of recruitment and distribution of lobster larvae, in the final stage.

The San Jorge Gulf (SJG) is an important oceanographic region due to the influence of two tidal fronts, being one of the most productive sectors and with greater marine biodiversity in the Argentine Sea. The aim of this study was to identify which oceanographic variables best explained the presence of marine mammals and to explore the overlap of the predicted richness with the frontal areas of the SJG during the austral summer. The potential distribution of 9 species (Balaenoptera sp., Cephalorhynchus commersonii, Globicephala melas, Grampus griseus, Lagenorhynchus australis, L. obscurus, Mirounga leonina, Orcinus orca, Otaria flavescens) was modeled with Maxent using 6 environmental variables (bathymetry, seafloor slope, distance to the coast, distance to the frontal area, sea surface temperature and chlorophyll a concentration). Marine mammals were found closer to the frontal area than expected by chance (9.48 km and 13.34 km, respectively). Bathymetry, distance to the coast and seafloor slope were the most important variables in the distribution of all the species. Balaenoptera sp., G. melas, G. griseus, L. australis and O. orca showed a coastal distribution (<10 km), mainly in the northwest of the gulf. The distribution of M. leonina, O. flavescens and C. commersonii followed the isobaths of 80 m, while L. obscurus evenly distributed throughout the gulf. In general, the environmental variables that influence the distribution of these species agreed with those found in previous studies from other locations. The area of high predicted richness was 75% overlapped with the frontal areas located in the northwest and southeast of the gulf. This work provides baseline information for designing future samplings that could explain the influence of the processes and the seasonal variation of the distribution of the marine mammals of the SGJ.

This study demonstrate the advantage of multi-model approach to calculate the growth of Crassostrea gigas cultivated in the Gulf of California. The generalized von Bertalanffy growth model (VBGM) and its modification to represent the seasonal variations (VBGM seasonal) were tested. The parameters of each model and their confidence intervals were computed using the maximum-likelihood method. The best-fitting model was selected using the Akaike information criterion (AIC). According to the AIC, the VBGM seasonal best described the growth of the C. gigas. The conclusion was that C. gigas exhibits a seasonal growth pattern under the cultivation conditions of the present study.

A juvenile specimen of the Green Turtle, Chelonia mydas, was recovered in Sicilian coastal waters close to Avola (Syracuse province, south-eastern Sicily, Italy). Before being released, the specimen was measured and inspected for the presence of ingested hooks or other possible harms to its health. A fragment of the mtDNA marker COI was amplified and sequenced in order to provide the first molecular data for the species from the central Mediterranean area. The possible influence of climate change on the occurrence of this thermophilic species in the central Mediterranean area is briefly discussed.

The Navachiste Lagoon System is connected to the Gulf of California (GC) via 3 tidal channels. The system has an area of approximately 301 km2, with an average depth of 2.5 m and an average tide height of 1.5 m. In order to simulate tidal currents and the effect of wind, a numerical hydrodynamic model was applied, integrated in the vertical and in finite differences; to calibrate the model, lagrangean measurements were made and compared with simulated currents in the tidal channels of the system. The model simulates the hydrodynamic behavior of the lagoon system and has a correlation higher than 85% with the trajectories traced by the drift bodies and with the maximum Eulerian velocities measured in the internal channels and in the mouths of the system.

The teleost fishes are the most diverse group of vertebrates and present a great variety in their reproduction form. Gonocorism is the most common form of reproduction among fish. However, a significant number of fish present hermaphroditism, that is, the same individual presents both sexes, simultaneously or sequentially. The point in time at which the sex change occurs is not necessarily instantaneous and can be interpreted at many different levels (by social, morphological and age behavior). The mechanisms of sexual determination and sexual differentiation are involved in this sex change and may be affected by the genetic inheritance or by the environmental changes in which an individual finds himself. The activity aromatase, estradiol, 11-ketotestosterone and testosterone are involved in the regulation of the reproductive process of hermaphroditic females and males. The pre-optic area (POA) and the hypothalamus are the two regions of the brain responsible for the control of the reproductive physiology and reproductive behavior of fish. Within the endocrine status of sequential hermaphroditic fish, great similarities with the endocrinology of gonochoric species are observed. Taming hermaphroditic species for reproductive purposes can bring great complications; the most common is to keep the desired sex ratio constant, therefore, the control of sex is a priority. To achieve this, it is necessary to know the reproductive physiology of the selected species and implement some strategy to manipulate this sex change, either through social factors or hormonal therapies.

Pacific harbor seals (Phoca vitulina richardii) range in North America from Japan to Mexico. Here we report the first record of a Pacific harbor seal feeding on Northern anchovy (Engraulis mordax) inside a purse-seine net of a sardine fishing boat in the Gulf of California. This event was recorded on video on January 11th, 2010, near Estero Tortuga, Guasimas, Sonora (27°50’N, 110°39’W). Sea conditions were of El Niño Southern Oscillation; this record was likely due to El Niño, forcing seals to travel beyond their distribution range in search of alternate foraging areas.