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

From 1999-2001, the Argopecten purpuratus population at La Rinconada was directly evaluated by monitoring larvae and their subsequent settlement on artificial collectors to determine their density, size structure, and abundance. An increase in specimens, doubling the number observed in 1997, occurred in 1999. However, reductions in the distribution area, specimens, and average size occurred in 2000 and 2001, reflecting anthropogenic impacts. Application of the growth parameters to the annual size structure indicated losses of 5.7 million individuals between 1999 and 2000 and 5 million between 2000 and 2001. The specimens increase over 90 mm, from 130,000 in 1997 to 2.6 million in 2001, explains the high larvae numbers found, with records of 17,667 and 21,756 in 1999; 16,100 in 2000; and 34,175 and 21,700 in 2001. A relationship between larval presence and postlarval settling could not be established; only the relationships between periods of larval abundance and those of maximum fixation could be observed. In conclusion, a viable solution to illegal fishing affecting the reserve with complementary or substitute measures for local fishers is urgently required.

Morphological alterations in zooplankton are induced by exposure to hazardous materials in the environment. These alterations in the body are excellent indicators of adverse effects at the (sub) individual and population levels. These changes might be undetectable within a population in the first generation; however, it was recently documented that alterations are more frequent in the subsequent generations. Because of this, we revised scientific literature that reported malformations in cladocerans, copepods, oligochaetes, and rotifers caused by diverse toxicants when organisms were exposed either in the laboratory or in natural conditions. From an environmental perspective, we focused on the importance of morphological alterations in zooplankton, the most likely causes, and their consequences. Furthermore, the present article shows that alterations of the normal morphology could be used as consistent biomarkers, but further research requires discriminating the influence of natural behavior and the consequences of exposure to toxic compounds.

We evaluated the inhibition activity of extracts from two common plants, moringa (Moringa oleifera) and croton (Croton californicus), against Vibrio parahaemolyticus (IPNGS16), which causes acute hepatopancreatic necrosis disease (AHPND). The experiment was developed in three phases. First, extracts were prepared, and phytochemical screening of plants was performed. Second, microbiological tests were applied to calculate the minimum inhibitory concentration (MIC). Finally, two bioassays were performed on juvenile shrimp by administering the extracts (first) in shrimp feed at 24 and 72 h, pre-infection, and the second in feed and directly to the culture water. Based on preliminary results of antimicrobial activity, an extract concentration of 60 mg mL-1 inhibited V. parahaemolyticus (IPNGS16) at a final concentration of approximately 1×106 CFU mL-1. Bioassays were carried out in order to determine the V. parahaemolyticus (IPNGS16) median lethal dose (LC50) for juvenile Penaeus vannamei (0.20 ± 0.05 g); the LC50 was 85×103 CFU mL-1. As a first test, the extracts were added to commercial feed at doses of 20, 40, and 60 mg mL-1. After feeding, the shrimp were infected with V. parahaemolyticus (IPNGS16), and mortality was recorded. For the first infection time (24 h), survival was 46 and 33% with croton and moringa, respectively; for the second infection time (72 h), survival was 16 and 25% with croton and moringa. Application of antibacterial extracts directly to culture water were effective against V. parahaemolyticus (IPNGS16). The best result (94% survival) was obtained with a high dose (3.6 mg mL-1 or 30%) of moringa extracts added directly to culture water. Moringa methanol extracts produce active compounds capable of inhibiting replication of V. parahaemolyticus (IPNGS16) in shrimp aquaculture and reducing shrimp mortality.

Five previously analyzed white spot syndrome virus (WSSV) strains from northwest Mexico, differing in their genome architecture as well as in virulence, were selected (high virulence JP and LG strains; moderate virulence GVE and DIV strains; and low virulence LC10 strain) to evaluate pathogenesis response in vitro. Expression of phagocytosis-activating protein PAP, manganese superoxide dismutase MnSOD and peroxiredoxin PRX, and two genes of immediate-early expression (IE1 and WSSV304) were measured by qPCR in a primary hemocyte cell culture from Penaeus vannamei at 1, 3, 6, 12, and 24 h post-infection (hpi). PAP expression was significantly higher at 1 and 3 hpi, and JP and LC10 strains induced the highest expression. The response of MnSOD was high at 1 hpi, and a significant increase in PRX expression was detected at 3 hpi, probably due to the occurrence of an oxidative burst; expression levels of MnSOD and PRX were significantly higher at 1 and 3 hpi, respectively, induced by the LG strain (high virulence), suggesting an acute response. In general, expression of most immune-related - genes decreased after the initial hours of infection. Expression levels of IE1 and WSSV304 were exceptionally high at 1 hpi in almost all five WSSV analyzed strains, confirming their efficient mechanism for replication and viral fitness. The results of this study do not show an accurate link between the genome size and WSSV virulence of the strains, albeit the strain with the smallest genome showed the highest virulence. All strains induced an early immune response in heterogeneous ways.

The stressing effect of stocking density and rearing time was assessed on shrimp Penaeus vannamei reared intensively in floating cages. Juvenile shrimp were stocked in 9 m2 cages at 200, 250, and 300 ind m-2 for a 25-day grow-out period. Total soluble protein concentration, superoxide dismutase (SOD), and catalase (CAT) activities were used as stress indicators in shrimp muscle, hepatopancreas, and hemocytes. Two-way ANOVA showed that protein content in hepatopancreas significantly decreased as stocking rate increased (from 3.81 to 2.26 mg mL-1). Density and rearing time interacted significantly to determine SOD activity in muscle and hemocytes where the maximum activity occurred at the densest rate by the end of the study (10.21 and 122.41 U mg-1); CAT activity in hepatopancreas was significantly lower when the highest density (4.1 U mg-1) was used. Final shrimp weight (5.28-5.49 g), survival (90.2-91.9%), feed conversion ratio (0.75-0.78), specific (0.058-0.063), and absolute (1.17-1.30 g week-1) growth rates were not significantly affected by density, although yields varied significantly (0.99-1.49 kg m-2). To conclude, despite the stocking rate causing a stressing effect on shrimp, its antioxidant enzymatic activity prevented such development from negatively affecting shrimp growth, survival, feed conversion ratio, and production.

Research on populations of the family Mugilidae is necessary for the framework of their good use and conservation, given the documented spatial-temporal variation in their attributes and biological processes. Mugil curema has also shown particularities in the southeastern Gulf of California, which should be considered. In total, 626 individuals were collected from February 2015 to August 2016. The gonad development pattern was asynchronous and divided into six ovarian and five testicular phases. The sex succession as size increases, the presence of only males in smaller sizes, some aspects of the ovarian structure, and the eosinophilic cells in the ovarian stroma suggest that M. curema could be a protandrous hermaphroditic species. Thus, the size at sexual maturity was smaller in males (18.26 cm in total length) than in females (22.08 cm). This information is greatly relevant for fishery management measures and the sustainable use approach and, at the same time, arouses interest in future research.

Microalgae can accumulate lipids during the stationary growth phase, but little information is available about fatty acid profile changes during this phase to determine the best harvesting time in respect to lipid content. In this study, Dunaliella sp. was cultured in F/2 medium at three different photon flux densities (380, 226 and 8.2 μmol photon m-2 s-1) and three different glycerol concentrations (0, 10 and 20 g L-1). Samples were taken during the stationary phase to assess lipid content and fatty acid profile variations. Microalgal biomass production was higher at 380 and 226 μmol photon m-2 s-1 than at 8.2 μmol photon m-2 s-1 in accord to light limitation. The maximum lipid content (345.78 mg g-1) was achieved at 8.2 μmol photon m-2 s-1 and 20 g L-1 glycerol at day 12, similar to that achieved at day 9 (334.16 mg g-1). The maximum polyunsaturated fatty acid amount (65.30 μg mg-1) was achieved at day 7 of culture without glycerol addition, decreasing in proportion over time. So, the best conditions and harvesting time in respect to fatty acid quality would be at 380 μmol photon m-2 s-1 without glycerol addition and after 7 days of culture.

Macrobrachium americanum is a large prawn living in rivers and coastal water bodies of tropical and subtropical ecosystems of the Pacific side of the Americas. Water temperature and salinity are the main physicochemical variables determining its distribution. Temperature also influences its metabolic rate, which determines growth rate and reproduction. Because of this, preferred temperature, critical thermal maximum (CTMax), and O2 consumption rates at four temperatures (20, 24, 28, and 32°C) were tested from wild prawns in laboratory assays. Those temperatures correspond to the annual temperature fluctuations at the sampling site. The final preferred temperature of this species is close to 26.4°C. The acclimatization temperature has an almost linear effect on the CTMax (R2 = 0.987, P < 0.05), and the oxygen consumption routine rates increased as the acclimation temperature increased from 20 to 32°C.

The sea urchin Loxechinus albus is of great commercial value due to its nutritional content. The main diet of the urchin in the north of Chile in its natural habitat is the macroalgae Ulva lactuca. This work evaluated the growth of L. albus juvenile fed diets based on vegetable lettuce Lactuca sativa and macroalgae Ulva sp. Ingestion, growth, survival, and proximal analysis of the diets were registered for 13 weeks. At the end of the experience (90 days), no mortality and greater consumption of L. sativa were observed. In the proximal analysis, L. sativa presented the highest percentage (lipids, proteins, ashes, carotenoids, chlorophyll). The greatest growth and weight gain were observed with the Ulva sp. diet. Finally, the incorporation of L. sativa in the diets of urchins would imply a supplement of minerals and carotenoids, so we propose the addition of this lettuce as a nutritional supplement during the first stage of the cultivation of the L. albus.

A notable diversity of marine mammals inhabits the Atlantic and Pacific waters of South America. For decades, South American countries have been producing scientific research focused on these species. However, still, there is no systematic assessment of the magnitude and main subjects on which this research has been focused. This study analyzes the trends and patterns in scientific research on marine mammals in South America, evaluating a pool of bibliometric indicators and mapping collaborative relationships among countries, authors, and research areas. Academic documents were retrieved from two bibliographic databases: SCOPUS and SciELO, from 1990 to 2020. Results showed a gradual increase in publications along the three study decades. Brazil played a central role in the number of publications in both databases, followed by Argentina and Chile. The South American publications on marine mammals were centralized in a small number of journals, and few authors were responsible for a large proportion of contributions. The authors showed a moderate level of collaboration, mainly reflecting stronger links among neighbor countries, including co-authorships with North American and European countries. The most frequent keywords reflected three clusters centered in taxonomic groups (Cetacea, Odontoceti, and Pinnipedia) and two centered in research subjects (pollution and phylogenetics). The scope of the contributions differed among collections. Nevertheless, both databases were complementary and contributed to show marine mammals' research in South America.