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

The reproductive cycle of the gastropod Hexaplex princeps (Broderip, 1833) from Puerto Ángel was studied through gonadal histology during two annual periods. The sex proportion for the total collected individuals was not statistically different from parity although most of the time the number of males was slightly larger than that of females, which only outnumbered males during the spawning season. The histological analysis of gonad sections permitted to establish six maturity stages for females: 1 Initial oogenesis, 2 Previtellogenic maturity, 3 Vitellogenic maturity, 4 Maturity, 5 Spawning, 6 Resting, and five for males: 1 Initial spermatogenesis, 2 Maturity, 3 Spawning, 4 Onset of the rest, 5 Resting). Monthly variations in the gonad maturation stages showed that H. princeps has an annual reproductive cycle with a long period of gonadal activity. The spawning season comprised from November to March (females) and from December to March (males) with peaks of activity for both sexes in January. Resting periods of females comprised from March to October and for males May and June. Thus the reproductive events were related to high Chlorophyll concentrations which in turn are due to the upwelling processes resulting from the winds during winter months (November to March). This study provides baseline information that may serve to establish measures for adequate exploitation and for aquaculture implementation of this species in the future.

Hermit crabs are common and abundant members of the intertidal community and in sublittoral bottoms, where they play a fundamental role in the trophic chain. This study aimed to determine the composition of the hermit crab fauna, to quantify the density in the natural environment, and to register shells use by main species from subtidal boulder fields, in an island off the southeastern Brazilian coast. Monthly samples were taken from March 2010 to February 2011 on boulder fields on Couves Island, Ubatuba, Brazil, during scuba diving daytime sessions. Three hundred and eighty-three crabs were collected by hand, in a quadrat of 20 m2 belonging to five species: Calcinus tibicen, Dardanus venosus, Pagurus brevidactylus, Paguristes tortugae, and Petrochirus diogenes. The highest densities were recorded for P. brevidactylus and P. tortugae. Hermit crabs occupied shells of 15 gastropod species. Cerithium atratum, Gemophos auritulus, and Morula nodulosa comprised more than 80% of the occupation. The heterogeneity of boulder fields of Couves Island, composed almost entirely of small refuges and crevices, favors the exploration of hermit crab species recorded here, which are characterized by small size. These results, combined with the findings of further studies, can contribute to the development of effective monitoring programs for decapod crustacean species.

The Reverse Osmosis desalination has become a technological option to guarantee an adequate drinking water supply in zones with water scarcity. Nevertheless, the process is accompanied by potential negative impacts on coastal ecosystem, especially due to chemical discharges. Taking into account the environmental risk presented by these chemical mixtures, in this work we used a short-term toxicity bioassay with Artemia franciscana nauplii expressed in lethality to exposures individually and their combinations. Results showed that toxicity degree from single exposures were C5H8O2 > NaClO > CuSO4 > KMnO4 > FeCl3, indicated that C5H8O2 was the most toxic biocide. However, all compounds in combination with C5H8O2 exhibited a very strong antagonism. Except, in mixtures NaClO/FeCl3 and CuSO4/KMnO4 resulted in additive effect. This environmental assessment will allow reduce risk significantly on the concentrate considering the sensitivity of the marine ecosystem to the application of chemical agents during the desalination process.

The immune response is critical in cultured shrimp facing pathogens that are serious concerns. Therefore, immune-related gene expression was investigated in Penaeus vannamei fed with Aloe vera. Shrimp weighing 2.9 ± 0.8 g were fed with 1 g of A. vera kg feed-1. Six shrimp were sampled at 0, 6, 12, 24, 48, and 72 h for gene expression. Samples of time zero were taken just before feeding with aloe. After feeding with aloe during 24 h, uneaten food and waste material were removed and then shrimp were fed only with commercial feed. Quantitative real-time PCR measured time series expression of four genes (translationally controlled tumor protein [TCTP], superoxide dismutase [SOD], heat shock protein 70 [HSP70], and penaeidin4). The expression of TCTP was down-regulated, and the expression of SOD, HSP70, and penaeidin4 was up-regulated. This is the first report showing the effect of A. vera on the modulation of shrimp immune response. The immunostimulant properties of A. vera could be useful for cultured shrimp health.

Vegetative and reproductive morphology of Ruppia filifolia (Philippi) Skottsberg is updated and completed by examining natural specimens, reviewing the literature, comparing to specimens from different locations and generating new iconography of the species from waters across the Magellan region, Subantarctic Chile. We expand current knowledge on morphology (rhizome-root, branching, foliage, inflorescence, fruit, habits) and geographical distribution of R. filifolia in Austral South America, with the addition of six new localities for the taxon in Chile. Our results are used to identify this macrophyte and to distinguish it from R. maritima after some authors reported their co-occurrence in the southern tip of South America, leading to taxonomic confusion. Also, the new information on R. filifolia distribution in the Magellan region broadens the research on a neglected seagrass. In the Southern Hemisphere, contrary to global trends of seagrass ecosystems decline, new niche distributions are opening up in southernmost Chile, reflecting environmental changes.

Length-weight relationships (LWRs) were estimated for Pacific blue marlin (Makaira nigricans), striped marlin (Kajikia audax), sailfish (Istiophorus platypterus), dolphinfish (Coryphaena hippurus) and yellowfin tuna (Thunnus albacares). These five fish species are key top predators of the pelagic ecosystem and are economically important resources in the sport fishing of Baja California Sur, Mexico. Overall, 53,359 length and weight records were analyzed for the period 1990-2015. LWRs were significant (P < 0.05), with b-values ranging from 2.52 to 3.13.

Sphoeroides testudineus (Linnaeus, 1758), is a common, widely distributed fish in coastal ecosystems. To better understand the trophic niche of S. testudineus, we collected individuals from tidal creeks on Abaco Island, The Bahamas, and employed stomach content and stable isotope analysis. Examination of stomach contents showed that mollusks, such as West Indian false cerith snails, cerith snails, and tellin clams, were the most common prey items. Diet data were consistent with stable isotopes data such that S. testudineus seem to feed at an intermediate trophic position in the food web. These preliminary data suggest that S. testudineus may be a critical intermediate link in these wetland food webs, serving as pathways through which energy is transferred from primary consumers to other predator species.

Records of white sharks (Carcharodon carcharias) sightings or captures from the southern Gulf of California have been poorly documented and anecdotal evidence is limited. Even rarer is the event of a juvenile in subtropical waters. In the present paper, we report the capture of a juvenile female white shark taken in the lower Gulf of California, which represents an important contribution among the connectivity between individuals from California, United States and the Gulf of California, Mexico.

The anchialine fauna from the Yucatan Peninsula has been extensively studied since the 1980´s. “Sea spiders” or Pycnogonida, have never been found in these systems before. A record for Anoplodactylus batangensis (Helfer, 1938) from a cenote (sinkhole) in the Yucatan Peninsula, Mexico is presented herein. The pycnogonid was found in waters of the cenote Nohoch Nah Chich, part of the Sac Actun anchialine system, in the State of Quintana Roo. This species was already reported from the northeastern shore of the Yucatan Peninsula, however the record we present herein constitutes the first time a pycnogonid is reported from an anchialine habitat. A brief description of the female A. batangensis is presented for the first time.

The objectives of the present study were to characterize biochemically the proteases present in gastric juices from adults of the southern king crab (Lithodes santolla) and the Chilean rock crab (Cancer edwardsii), to determine the classes of proteases using specific inhibitors, as well as to evaluate the effect of temperature and pH that affect the proteolytic activity. The enzyme activity analysis revealed non-significant differences between the activities of serine proteases (trypsin and chymotrypsin) in both species. On the other hand, acid protease activity in C. edwardsii was significantly higher than in L. santolla. The activity of aspartate proteases was inhibited by Pepstatin A in both species, with no significant differences in the extent of inhibition between them. The maximal enzyme activity detected for both species occurred at alkaline pH. The optimum pH for proteolytic activity was ranged between 7 and 9 for C. edwardsii, and between 7 and 11 for L. santolla. Moreover, the highest proteolytic activity was recorded at 60°C in both species. However, at this temperature, enzyme activity was unstable after 20 min. Finally, collagenase-like activity in the gastric juices was detected for both species; this activity deserves further investigation, considering its biotechnological potential.