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

In the north-central zone of Chile (25°00’-31°40'S), zooplankton samples were taken in 103 oceanographic stations during February-March 2017 (0-70 m). Ostracods were separated, identified, and counted, making it possible to determine their distribution, abundance, species richness, and diversity. Twenty-one species belonging to 12 genera of the Halocyprididae family were identified, three of which had not been previously reported for the southeastern Pacific (Conchoecetta acuminata, Mikroconchoecia stigmatica, and Orthoconchoecia atlantica). The highest abundances, species richness, and diversity were found mainly in stations away from the coast (10 and 20 nm), sampled in hours of darkness. The most abundant species with the highest frequency of occurrence were Archiconchoecia striata, Conchoecetta giesbrechti, Conchoecia magna, and Halocypris inflata. A. striata constituted more than 50% of the total abundance of the ostracods identified.

A comparative study of serum biochemical and hematological parameters from Andinoacara rivulatus and Ichthyoelephas humeralis in Los Ríos Province, Ecuador, was carried out. Two of the native species that are the most commercialized in Quevedo, Mocache and Fumisa, were identified; 60 specimens were captured in each area (180 total). A factorial design (3×2) was used: three habitat zones (Fumisa, Quevedo, and Mocache) and two species (A. rivulatus and I. humeralis). Sex, weight, length, serum biochemistry (total protein, albumin, globulin, albumin/globulin ratio, aspartate aminotransferase (AST), alanine aminotransferase (ALT), calcium, phosphorus, sodium, magnesium, and potassium), hematological parameters (hemoglobin, hematocrits, erythrocytes, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), total leukocytes, granulocytes leukocytes, and agranulocytes leukocytes) in fishes were determined. There was zone-species interaction for all indicators except MCH and MCHC (P < 0.05). For total proteins, albumins and ALT were for I. humeralis in Fumisa and Mocache zones (2.81, 1.57, and 326.67 g dL-1, respectively). In comparison, A. rivulatus was higher in Fumisa and Quevedo in globulins and the albumins/globulins ratio with 2.28 g dL-1 and 2.14, respectively. Electrolytes were found in low concentrations in the two species. For the hematological parameters, all presented significant differences (P < 0.05) except MCH and MCHC. For I. humeralis, its highest values were presented in hemoglobin with 13.37 g dL-1 in Fumisa, for MCV and total leukocytes (93.11 fL-1 and 8.03×103 μL-1) respectively, in the Mocache area. This study will provide essential tools in monitoring the health status of these fish species in particular and fish species in general.

In recirculating aquaculture systems (RAS), the water exchange rate influences the removal of waste compounds. However, the inappropriate exchange rate favors the presence of stress factors, causing alterations in the cultured organisms. Therefore, the aim was to determine the effect of the water exchange rate in the different productive stages (fingerling, juvenile, and adult) of Nile tilapia (Oreochromis niloticus). Three exchange rates were used: rates of 1.2 (T1), 2.8 (T2), and 5.3 (T3) tank volume h-1. The following were established as response variables: growth rate (GR), survival rate (SR), feed conversion rate, protein efficiency, and condition factor. Likewise, cortisol and glucose concentrations were established as explanatory variables. The results suggest that in the fingerling stage, the T2 treatment contributes most to the productive performance (GR = 40.24 g and SR = 95%), keeping low levels of cortisol and glucose (6.76 ng mL-1 and 33.73 mg dL-1). In the juvenile stage, T3 treatment shows the best result both in productive performance (GR = 117.69 g and SR = 90%) and in cortisol and glucose concentrations (35.13 ng mL-1 and 70.67 mg dL-1). Finally, all treatments present cortisol and glucose levels above the normal range in the adult stage, T1, where the highest productive performance is presented (GR = 90.06 g and SR = 95%). The information leads us to consider the variation in the exchange rate in a RAS through the different stages of the Nile tilapia to maintain the favorable conditions that lead to the highest performance.

Epitheliocystis is an emergent infectious disease affecting fish gills and skin worldwide. Few studies document their distribution in wild and cultured fish in Latin America. This study reports the epitheliocystis distribution and prevalence, histopathological index (HI), and its possible relation with other observed pathologies in the gills of cultured tilapias Oreochromis niloticus in ponds and cages of three states of southwestern Mexico. In Guerrero, the number of affected fishes was less (29.2%) compared to Oaxaca (39.8%) and Chiapas (49.1%), with significant difference (Gadj = 13.39, df = 2, P = 0.01). The size of the cysts was between 5.37 to 52.96 μm, and most of the analyzed fish showed a low number of cysts per gill arch. The prevalence by regions was varied (0 to 75%) and no correlation (r = -0.002, P = 0.659, n = 474) between epitheliocystis prevalence and type culture. The fish had a low infestation of Trichodina sp. and monogeneans plus different pathologies such as inflammation, eosinophilic cells, rodlet cells, telangiectasia, edema, and thrombosis. The correlation analyses show a low inverse correlation (r = -0.281, P = 0.000, n = 474) between epitheliocystis prevalence and fish weight; and a low correlation (r = 0.372, P = 0.000, n = 474) between epitheliocystis prevalence vs. HI. The presence of the pathologies registered in this study seems to be possibly associated with other conditions like water quality or toxicants. This research is the first scientific study documenting the presence and distribution of epitheliocystis in Mexico.

An autonomous lander equipped with a video camera (dropcam) was used for in situ observations of the bento-demersal macrofauna on the upper continental slope off Punta Pichalo in northern Chile, an area of permanent coastal upwelling processes, located ~70 km north of Iquique. The lander was deployed at nine stations and between 227 and 798 m of depth. According to morphological characteristics, 34 operational taxonomic units (OTUs) were identified to the lowest taxonomic level; 24 belonged to macroinvertebrates and 10 to fishes. Macroinvertebrates comprised 9 OTUs of crustaceans, seven cnidarians, and six echinoderms. Fishes included 3 OTUs of the order Chondrichthyes, 3 belonging to macrourid. Perciformes, Anguilliformes, and Alepocephaliformes were represented by one OTU each. Also, we observed one species of lanternfish (Myctophidae). Apart from the brachyuran decapod Lophorochinia parabranchia Garth, 1969 and euphausiids, all species were observed at depths greater than 560 m. The presence of one individual identified as the granulate dogfish Centroscyllium granulatum Günther, 1887 extended the known distribution range of this species about 1000 km to the north. Images taken at 795 m showed Bathyraja peruana McEachran & Miyake, 1984. Our study suggests that the upper continental slope of northern Chile harbors nearly undiscovered biodiversity, worth to be studied more intensively to complete the comparable sparse knowledge about marine biodiversity and species distribution at the continental margin in front of Chile.

This study describes the spatial distribution and abundance of siphonophores concerning oceanographic variables (temperature, salinity, and dissolved oxygen) in the northern Chilean Patagonian Fjord Ecosystem, from Guafo Passage (43º30'S) to Elefantes Gulf (46º40'S) during the winter of 2012. Twelve species were identified, ten belonging to suborder Calycophorae and two assigned to suborder Physonectae. The species Chelophyes appendiculata and Sphaeronectes gamulini are new records for this study area. Dominant species were Muggiaea atlantica (63.15%), Lensia conoidea (21.85%), and Sphaeronectes koellikeri (9.91%). Species richness showed a negative latitudinal gradient, and the highest densities were found in North Moraleda Channel (5316 ind 1000 m-3) and the lowest in South Moraleda Channel, near Elefantes Gulf (71 ind 1000 m-3). Some species showed a significant and positive association with some oceanographic variables, e.g., M. atlantica showed a positive association with dissolved oxygen, L. conoidea with temperature and negative association with dissolved oxygen, Sphaeronectes fragilis, S. koellikeri, and C. appendiculata showed a positive association with salinity. Eudoxids (sexual reproductive stage) were found for M. atlantica, L. conoidea, and Dimophyes arctica, indicating that the PFE conditions are suitable for some siphonophore species even in winter.

This study aimed to identify anatomopathological injuries in sick, moribund, or recently dead fish from an experimental fish farm in the Peruvian Amazonia with a necropsy, direct microscopic, and histopathological examination. The study was carried out at the migratory fish production unit where cachama (Colossoma macropomum), pacus (Piaractus brachypomus), black prochilodus (Prochilodus nigricans), and spotted tiger shovelnose catfish (Pseudoplatystoma punctifer) are bred. Furthermore, from the non-migratory fish unit where arapaima (Arapaima gigas) and Nile tilapia (Oreochromis niloticus) are bred at the fish farm within the Experimental Station of the IVITA Research Center in Ucayali, Peru. Thirty clinical cases distributed in thirteen incidents of diseases observed between January 2013 and June 2014 were evaluated. The tissue macroscopic and microscopic evaluations were performed through necropsies to determine the injuries and the possible causes of mortality. Samples of the skin and gills mucous membrane were collected to identify parasites by direct microscopy, and liver, kidney, and spleen imprints stained with Gram were made to observe the presence of bacteria. Histopathological analyzes of the affected tissues were also performed in some of the evaluated cases. Parasites, mainly trematodes, were found in cachama, protozoa in arapaima, and bacteria suggestive of Flavobacterium sp. in spotted tiger shovelnose catfish. Digestive (14/30), respiratory (9/30), and traumatic (3/30) injuries were identified.

Nematodes are among the most common parasites in aquatic mammals. Because of their cuticular covering, these worms are frequently collected from the examination of feces or stranded hosts. This work provides new records of three nematode taxa infecting three different aquatic mammal species (Lontra longicaudis annectens, Trichechus manatus, and Zalophus californianus) in Mexico. Additionally, it brings together all available published records about this country's nematode fauna parasitizing aquatic mammals. The aim is to describe the current state of the art, which sets the basis for the strategic design of future research. Given the diversity of printed sources recording nematode fauna, we gathered literature, including theses and articles in journals profiled in the Journal Citation Reports or similar academic databases. The compiled information shows that 24 nominal nematode taxa have been reported from 11 species of aquatic mammals in Mexico. Our study exhibits irregular patterns of geographic distribution and host spectrum, existing entire marine ecoregions, and numerous host species lacking records.

While fishing discards and bycatch are worrisome for fisheries management, research has been mainly focused on commercial or threatened species, while the ecosystem effects were largely neglected. In this work, the effects of discard and fishing efforts on the structure and the functioning of the food web of the Río de la Plata (RdlP) were analyzed using mass balance and dynamic trophic modeling. Discard is consumed almost entirely by several species with a large preference for it, producing mixed trophic impacts. The role of discard on the global attributes of the RdlP ecosystem does not seem important, resulting in a low incidence in trophic flows, growth, and development of the trophic web. Dynamic simulations showed a mixed response to variations of discards, with some groups responding positively and others negatively. For example, a decrease in discards would produce a slight decrease in the biomass of most functional groups, being more pronounced in the predators of the system. Variations in biomass produced by discards are more sensitive under the assumption of bottom-up ecosystem control than mixed control and to a lesser extent under top-down control. Our work confirms a complex relationship between discards and ecosystem functioning, warning about the beneficial result of discard reduction policies.

Enteric viruses are major causes of waterborne diseases and are present in large quantities in the stools of infected individuals. Its viability in the environment lasts for months, favoring the contamination of water used for consumption and recreation. The study aimed to monitor monthly the circulation of enterovirus (EV) and group A rotavirus (RVA) in recreational freshwater from an island region used as a bathhouse in northern Brazil, from January 2012 to December 2013. The viral RNA was obtained using guanidine isothiocyanate/silica after viral concentration by adsorption-elution method. The molecular detection was carried out by semi (EV) and nested-PCR (RVA) and the amplicons were sequenced on automated sequencer. At least one of these viruses was detected on 40.4% (42/104) of the samples. RVA was the most frequent (n = 32; 30.8%) when compared to EV (n = 20; 19.2%). Co-circulation between both was identified in 9.6% (n = 10). The highest viral positivity was found in SP02 (46.1%). The highest viral positivity was observed during high tides (57.7%; 60/104). Most EV samples were characterized as coxsackievirus (CV) A5 (85.7%, 12/14) and others as Sabin 1 poliovirus (14.2%, 2/14). The RVA positive samples were genotyped as G2, G3, G9, G12, P[8], P[4], and P[6]. These viruses were detected in 35.6% (37/104) of the samples with an acceptable concentration of fecal coliform bacteria. These results demonstrate the contamination of surface water intended for recreation by enteric viruses of Public Health concern even when bacterial indicators are within the tolerated limit, a factor that confirms the need for public policies aimed the sewage treatment before its release into water bodies.