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

This paper describes histological findings in the liver of Lutjanus guttatus after an acute mortality event in fish cultivated by river fishermen from Colima, Mexico, who were making their first attempt to cultivate this species. During 187 days, divided into two stages, 20,000 juveniles (6 g) were randomly distributed in three floating cages (125 m3). During the first 110 days (pre-fattening), the fish were fed commercial feed. From days 111 to 180 (fattening), the fish were given a test feed, high in fat (20.4%) and low in protein (30.2%). At the end of the first stage, the fish showed good biometric parameters as well as normal behavior and healthy appearance. During the second stage, starting on day 175, a strange behavior was observed followed by an acute mortality event; this alarmed the group of fishermen, who requested our intervention. In the necropsy and the histopathological analysis, the liver of the fish showed clear evidence of hepatocellular steatosis, possibly as a result of the nutritional stress to which they were subjected during cultivation. The present work can serve as a basis for future research, given the scarce information of this pathology in this fish species.

In order to optimize the performance and reduce costs in the larviculture of ornamental carp (Cyprinus carpio) in a recirculating aquaculture system, different feeding strategies were tested. For this, two experiments were carried out both under controlled conditions in a greenhouse, in a recirculating aquaculture system with a physical particle filter, biofilter, and filtering by ultra-violet irradiation. In the first experiment, measurements of Artemia nauplii were tested in the initial exogenous feeding of larvae at concentrations of 100, 200, 400, 600, 800 and 1,000 Artemia nauplii per larvae. In the following experiment, different protocols were tested for initial feeding for larvae. At this stage, were used: live food (Artemia nauplii) and inert (powder meal), used separately and simultaneously, and increases in the number of Artemia nauplii were also tested, offered at different times of cultivation. In the first experiment, the amount of 600 Artemia nauplii for larvae demonstrated to be the best option as it generated significant growth and the cost was less than that observed with the use of 800 and 1000 Artemia nauplii per larvae. The second experiment demonstrated that the feeding strategy with live food more commercial inert feed provided the best growth performance for ornamental carp larvae. The need to fix the amount of live food during the cultivation, probably due to the high specific growth rates observed during the larval stage also became evident.

The effects of Gymnodynium catenatum and Prorocentrum lima, dinoflagellate species present in the Gulf of California, on marine bivalves, have demonstrated physiological alterations and changes in gene expression patterns; however, modification effects of the genes involved in immune defense are still poorly understood. This study analyzed the mRNA levels of five genes encoding for the immune defense of oyster Crassostrea gigas spat fed with a control diet (Isochrysis galbana alone) and a combination of the two toxic dinoflagellates. Expression levels of lipopolysaccharide (LPS)-binding protein 1,3-glucan and cavorting genes were higher in oysters exposed to the combined diets in all treatments compared to the non-toxic diet at day three, which was probably related with an activation of the oysters’ immediate immune response during the first 24 h. Protein 44 interferon-induced gene expression level was repressed in treatments with the highest dinoflagellate concentration and overexpressed in the diet with equal dinoflagellate concentration. Interaction protein-Toll and immunoglobulin gene transcript levels reached the highest values at day seven in oysters exposed to all combined diets. Then, the immune defense appeared to be activated in oyster spat as a response of toxins and/or extra-cellular compounds produced by the dinoflagellates. 

Hypanus marianae, a stingray endemic to Brazil, inhabits coastal coral reef areas occurring in the landings of artisanal fisheries. The present study aimed to characterize the diet of this species captured off Pernambuco. We obtained 77 stomachs with contents: 52.27% female, 47.72% male. DW ranged from 15 to 37.80 cm mean of 26.53 ± 4.82 cm. Four higher taxonomic prey categories were identified: Arthropoda, Annelida, Chordata and Sipuncula. The most important item in the diet was Polychaeta (40.65% IRI), followed by Leptochela serratorbita (30.35% IRI), suborder Dendrobranchiata (10.18% IRI), order Isopoda (4.19% IRI), and Meiosquilla schmitti (3.56% IRI). H. marianae displays specialized predatory habit (BA = 0.06) primarily based on shrimps (42.36% IRI) and polychaetes (40.65% IRI). There was no significant difference in the diet by sex or in sexual development stages. However, neonates fed on decapods crustaceans (70.68%) and polychaetes (17.09%). For immatures, decapod crustaceans (69.5%) and polychaetes (25.86%) made up most of their diet. The adults feed mainly on polychaetes (62.79%) and crustacean decapods (30.47%), with a slight increase of fish (5.46%). The trophic level (TL) estimated was based on stomach content analysis was 3.66 and estimated on the analysis of stable isotopes being 3.29, which classified the species as a mesopredator.

The trypsin enzyme of white shrimp Penaeus vannamei is a polymorphic molecule, which longest isolated and sequenced cDNA encoded a pre-proenzyme of 255 amino acids. Three of the described sequences are translated in the digestive gland, and SDS-PAGE detects the isoforms. The three isoforms named C, B and A are distributed by an individual to originate three trypsin phenotypes (CBA, CB and CA) that have already been isolated and characterized by defining theirs biochemical and kinetical differences. The CBA phenotypes exerted higher hydrolytic capabilities than the others. The trypsin phenotypes are inherited in a Mendelian fashion, and external or internal factors do not modulate them. In commercial hatcheries in Sinaloa, México, the most abundant phenotype was CBA, followed by CB and CA. The following two hypotheses may explain this finding: phenotype CA is not chosen throughout the selection process of breeders because they do not fit the anatomical characteristics desired by professionals in aquaculture or it is possible that shrimps with the CA phenotype die during the early stages of development. Two experimental designs were developed trying to explain such hypotheses and, in both experiments, CA phenotype frequency declined to zero when shrimps reached around 5 g of body weight. So far, no evidence explains the mortality of juvenile shrimps with phenotype CA. Research is needed to explain why CA phenotypes disappeared, how the survival of this phenotype can be improved, and how to produce shrimps with the most hydrolytic capability in support of the shrimp aquaculture industry. 

The Caribbean spiny lobster Panulirus argus (Latreille, 1804), previously considered to range from North Carolina, USA, to Rio de Janeiro, Brazil, and throughout the wider Caribbean region, was recently divided into two species based on morphology and coloration: Panulirus meripurpuratus Giraldes & Smyth, 2016 in Brazil, and P. argus north of the Amazon-Orinoco River plume. Here we report on the presence of two individuals of P. meripurpuratus and four of Panulirus laevicauda (Latreille, 1804), another species typical of Brazil, in Bahía de la Ascensión, Mexico. This bay is located in the area where the Caribbean current - the main route by which South Atlantic water can reach this coast after entering the Caribbean basin through the Lesser Antillean passages - impinges the Mexican Caribbean coast before turning north to give rise to the Yucatan Current. The potential for larval retention is increased in this area, potentially explaining the episodic occurrence of Brazilian spiny lobster species in Bahía de la Ascensión.

The larval development of Phylladiorhynchus pusillus is described from plankton specimens from the coast of Easter Island (27°20’S, 109°40’W). The morphological description of five zoeae and megalopae are given, comparing the meristic characters of the larvae with those of other galatheids, and the differences that allow their discrimination. The first larval stage of P. pusillus differs from the larvae described for the genus Galathea, by the slight segmentation between the basi and exopodite of the third maxilliped, in addition to the presence of four plumose setae at the distal end of the exopodite. The second zoea can also be differentiated because the number of plumose setae is maintained at the distal end of the exopodite, with two setae less than its congeners of the genus Galathea. The scientific name of the species is discussed, which is one of the two Galatheidae species from the coasts of Chile, according to Ahyong et al. (2010) classification. The most notable difference of the examined zoeae, concerning the other species, and what is described for P. integrirostris, is the slight segmentation between the exopodite and the basipodite of the third maxilliped and the presence of four plumose setae on the distal end of the exopodite.

A recent study of the meiofauna from several intertidal sites along the coast of Chile yielded several gastrotrich specimens. The number of specimens was too small to assess the ecology of the individual species; however, as there are no published records of Gastrotricha in Chile until recently, it is important to document the presence of this group in order to stimulate further research. We report specimens of the genera Lepidodasys, Cephalodasys, Macrodasys, Tetranchyroderma, Xenotrichula and several morphotypes of Turbanella. Additionally, we provide some initial data on the population density of Lepidodasys sp. at Coihuin (Puerto Montt) and an observation of them feeding on nematodes.

The effect of adding vegetable substrates: wheat bran (WB), oat bran (OB) and amaranth seeds (AS) on water quality, biofloc composition and production response of Penaeus vannamei intensively pre-grown, was evaluated during five weeks. Water quality parameters (temperature, pH, salinity and dissolved oxygen) were monitored twice a day; nitrogenous compounds (TAN, NO2-N, NO3-N) and the total suspended solids (TSS), were recorded weekly. Weight gain and survival of juveniles were monitored each week. Chemical proximate composition of biofloc and content of heterotrophic bacteria were recorded at the end of the trial. No significant differences were observed for any of the water quality parameters or nitrogenous compounds. The TSS was higher in treatments with substrates compared to the control. The treatment WB showed the highest content of heterotrophic bacteria. Organic matter in the bioflocs ranged from 58.3 to 62.4%, proteins from 33.4 to 37.6%, lipids from 0.4 to 0.5% and carbohydrates from 17.1 to 25.5%, without significant differences in any of them among treatments. The mean final weight varied from 1.10 to 1.38 g, and specific growth rate from 5.83 to 6.43% d-1, with the highest values in treatment OB. Final survival ranged from 93.7 to 98.8% without significant differences among treatments and the control. The feed conversion ratio varied from 0.92 to 1.20 with the lowest value in OB compared to the control. The results suggest that supplementation of substrates does not have a negative effect on water quality, but have positive effects on the productive response of shrimp during their pre-grown, being oat bran the most adequate.

Four experimental diets were formulated with 50, 100, 150 and 200 mg of phenolic compounds (PCs) kg-1 feed, derived from mango peel. The control diet did not contain PCs. A total of 120 male zebrafish (Danio rerio) (average weight: 166 mg) were fed for eight weeks to assess the ability of PCs to prevent lipid peroxidation and enhance antioxidant status. Growth performance was calculated at the end of the experimental trial. Lipid peroxidations in muscle and antioxidant enzyme activity in the liver were evaluated at the end of the experiment. There was no significant difference in growth performance among treatments. Malondialdehyde (MDA) levels in muscle were significantly lower in fish fed diets containing 50 and 100 mg of PCs per kg of feed. Incorporation of PCs into zebrafish diet did not have any significant effects on glutathione peroxidase and superoxide dismutase activity. However, catalase (CAT) activity increased significantly in fish with diets containing 100, 150 and 200 mg of PCs kg-1 feed. These results suggest a potential protective effect against in vivo lipid peroxidation and CAT-modulating effects.