Scielo RSS <![CDATA[Latin american journal of aquatic research]]> http://www.scielo.cl/rss.php?pid=0718-560X20170002&lang=es vol. 45 num. 2 lang. es <![CDATA[SciELO Logo]]> http://www.scielo.cl/img/en/fbpelogp.gif http://www.scielo.cl <![CDATA[<b>Conservation of Brazilian coral reefs in the Southwest Atlantic Ocean</b>: <b>a change of approach</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200001&lng=es&nrm=iso&tlng=es Brazil has the most extensive and richest areas of coral reefs in the South Atlantic Ocean, with its fauna characterized by high endemism and adaptations related to its growth and morphology, to its coral building fauna and to the depositional environment that differ from other coral reefs around the world. In spite of the effects from changes in the global environmental, the main stress factors for Brazilian reefs are local level threats, such as pollution and overfishing. The effects from these threats reduce biodiversity and result in decreasing stocks at different trophic levels. The trend that currently exists, regarding marine resource use, implies that reassessing the conservation strategies is urgently necessary if the degradation of these environments is to be reversed. It is necessary that the practices used in adjacent watersheds be improved, combined with actions to protect and recover native vegetation, along with planning for developing coastal areas, which will ensure that sedimentation rates be controlled and pollution sources are drastically reduced. Brazil should have to adopt a multidisciplinary approach to lead an evolution from traditional threat management in individual portions of ecosystems to large-scale management strategies in complex socio-economic and natural systems. <![CDATA[<b>Manano oligosacáridos como prebióticos en acuicultura de crustáceos</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200002&lng=es&nrm=iso&tlng=es Los prebióticos tienen el potencial de incrementar la eficiencia y sostenibilidad de la producción acuícola. Uno de los prebióticos más promisorios en acuicultura son los Manano oligosacáridos (MOS). Estos MOS son moléculas de carbohidratos complejos derivados de la pared de la célula de la levadura Saccharomyces cerevisiae, que impiden la adhesión de patógenos bacterianos porque actúan bloqueando la adherencia de las lectinas microbianas con los carbohidratos presentes en la superficie de las células intestinales. Esta prevención de la adhesión impide la colonización y proceso infectivo de los patógenos. La ventaja del uso de MOS es que puede prevenir infecciones a través de mecanismos diferentes a los utilizados por los antibióticos. Este artículo muestra los avances obtenidos en uso de MOS como prebióticos en la acuicultura, en particular en el cultivo de crustáceos, donde han generado respuestas positivas en todas las experiencias actuando sobre el incremento del crecimiento, la supervivencia, modulando la respuesta inmune y modificando la morfología del tracto digestivo. La identificación de las cepas que son promovidas o excluidas y la caracterización de la acción moduladora en la microbiota resultante quedan abiertas como uno de los campos a desarrollar en conjunto con la extensión de estos resultados a la práctica productiva.<hr/>Probiotics have the potential to increase the efficiency and sustainability of aquaculture production. The mannan-oligosaccharides (MOS) are complex carbohydrates derived from the cell wall of the yeast Saccharomyces cerevisiae, which act by blocking adherence of bacterial lectins to carbohydrates on the surface of intestinal cells; this action prevents colonization and infection processes carried out by bacterial pathogens. In this work, we review the current evidence about the use of MOS as prebiotics in shellfish aquaculture, enlightening the positive responses in most of the experiences, such as improvement in growth and survival, modulating the immune response and modifying the morphology of the digestive tract. The identification of strains that are promoted or excluded, and the characterization of the resulting modulating action in gut's microbiota, remains open as one of the fields to be developed in conjunction with the extension of these results to the productive practice. <![CDATA[<b>Nuevas perspectivas en la diversidad funcional de ambientes marinos</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200003&lng=es&nrm=iso&tlng=es Los ambientes marinos están sujetos a presiones antropogénicas que afectan su biodiversidad y diversidad funcional. Los estudios con enfoque funcional identifican el papel de las especies en el ecosistema mediante el análisis de sus atributos; esto representa una alternativa más robusta que los estudios clásicos de enfoque taxonómico. Tradicionalmente sólo los atributos tróficos han sido considerados en los análisis de diversidad funcional en ecosistemas marinos, cuando existe una infinidad de atributos no tróficos relacionados con la funcionalidad de las especies. Se analizaron algunos índices de estimación de la diversidad funcional, así como el proceso de selección de los atributos funcionales para entender críticamente su utilidad. El enfoque funcional podría ser fundamental para mejorar su comprensión y generar medidas efectivas de protección que permitan desacelerar y de ser posible, revertir el proceso de pérdida de la biodiversidad a escala global. Finalmente, se reformulan preguntas de investigación y propuestas de hacia dónde se debería enfocar esta área del conocimiento.<hr/>Marine ecosystems are under anthropogenic pressures degrading both biodiversity and functional diversity. Functional diversity studies identify species functions through trait analysis, and are a robust alternative to the classical taxonomic approach. Although trophic traits are considered predominantly when analyzing functional diversity on marine ecosystem studies, there are other functional traits related to the species functions in the ecosystem. To critically understand the use of existing functional diversity indexes, we analyze them and their trait selection processes. The functional diversity approach improves our understanding of ecosystems and can help us slow and reduce the global-scale biodiversity loss by developing effective frameworks for monitoring and protection. We present some study questions and suggestions about how research should be oriented through functional analysis. <![CDATA[<b>Efecto de cuatro pretratamientos en la digestión anaeróbica y la remoción de nutrientes de efluentes, de un sistema de recirculación acuícola</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200004&lng=es&nrm=iso&tlng=es Los sistemas de recirculación acuícola producen efluentes (fracción disuelta y fracción particulada) con altas concentraciones de nitrógeno y fósforo que son una fuente potencial de contaminación si no se tratan en forma adecuada. El tratamiento de los lodos y remoción de nutrientes por medio de la digestión anaeróbica se ha vuelto una alternativa viable para la reducción y la estabilización de los lodos provenientes de los sistemas de recirculación acuícola. El presente estudio determinó el efecto de cuatro diferentes pretratamientos (alcalino, mecánico, térmico y biológico) en la reducción de los lodos, la desnitrificación, la producción de biogás y la dinámica del nitrógeno y el fósforo proveniente de los efluentes de un cultivo de tilapia nilótica (Oreochromis niloticus, Linnaeus, 1758) en condiciones hiper-intensivas con experimentos mensuales durante un año, con duración de 15 días cada uno. Tras la aplicación de pretratamientos en los lodos de origen acuícola, se obtuvo un aumento en la liberación de nitrógeno amoniacal total con respecto al control, de igual forma se obtuvo una remoción de nitritos en todos los pretratamientos (>90%), se incrementó la remoción de sólidos suspendidos totales, siendo mayor en los pretratamientos (>20,3%) en comparación con el control (14,6%), así como también se incrementó la producción de biogás, siendo el pretratamiento biológico donde se obtuvo la mayor concentración (45,18 cm³ L-1). Esto indica que la aplicación de pretratamientos en los efluentes acuícolas mejora los procesos de desnitrificación y digestión anaeróbica, pudiendo reducir los tiempos de retención hidráulica.<hr/>Intensive aquaculture recirculating systems produce effluents (dissolved and particulate solids) with concentrations of nitrogen and phosphorus, a potential source of pollution if they are not properly treated. The sludge and nutrient removal by anaerobic digestion has become an alternative for aquaculture sludge digestion and stabilization. In this study we determine the effect of four different pretreatments (alkaline, mechanical, thermal and biological) in sludge reduction and denitrification efficiency, biogas production and nitrogen and phosphorus dynamics from a hyper-intensive Nile tilapia (Oreochromis niloticus, Linnaeus, 1758) culture in 15 days experiments, one per month for one year. After application of pretreatments in aquaculture sludge, an increase in the release of total ammonia nitrogen was obtained with respect to the control, in the same way nitrate removal was obtained in all pretreatments (>90%), The increase in total suspended solids removal was higher in pretreatment (>20.3%) compared to control (14.6%), As well as the biogas production increase, being the biological pre-treatment where the highest concentration was obtained (45.18 cm³ L-1) The results indicate thatthe application of pre-treatments in the aquaculture effluents improves the denitrification processes and anaerobic digestion and can reduce the hydraulic retention time. <![CDATA[<b>Effect of light intensity and photoperiod on growth and survival of the Mexican cichlid, <i>Cichlasoma beani</i> in culture conditions</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200005&lng=es&nrm=iso&tlng=es Wild populations of the green mojarra Cichlasoma beani, are being pressured by anthropogenic activities. It is possible to mitigate the deterioration of native species populations by developing culture techniques. Environmental factors such as light intensity and photoperiod may affect the development of fish under culture conditions. Therefore, the aim of the present study was to examine the effect of these factors on growth, survival, and condition of C. beani cultured in different light intensities and photoperiods. Light intensities of 1000, 1500 and 2000 lux and photoperiod 24:00, 16:08 and 08:16 Light:Dark (L:D) were tested in 40 L tanks (10 fish per tank, three replicates per treatment) during eight weeks. There were no significant differences in light intensity or photoperiod, which was associated with the natural adaptation of the species to these factors. The results also suggested the favorable overall growing conditions during the trial and he response of the life cycle stage of the specimens used in this study. The results of the present study indicate that the natural adaptations of C. beani, allow the favorable culture in various light conditions in juveniles, which can be advantageous for commercial culture as may imply low energy costs. <![CDATA[<b>Evaluación de la pesquería de palangre artesanal y su efecto en la raya látigo (<i>Dasyatis guttata</i>) en Isla Zapara, Golfo de Venezuela</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200006&lng=es&nrm=iso&tlng=es RESUMEN. La raya látigo Dasyatis guttata es una especie objetivo en la pesca artesanal del sur del Golfo de Venezuela. A pesar de su importancia económica, actualmente pocas evaluaciones se han efectuado para conocer su estado. Con el seguimiento de las actividades pesqueras de la flota artesanal de Isla Zapara, se evaluaron las características morfométricas, composición de sexos, captura por unidad de esfuerzo (CPUE, ind/1000 anzuelos), de D. guttata, durante seis meses continuos de muestreo (18 días de pesca). Los muestreos biológicos mensuales incluyeron el ancho de disco (AD), peso total (PT), y sexo. Se evaluó a) la relación talla-peso para cada sexo, b) el factor de condición mediante el índice de Fulton (K) mensual, y c) la CPUE. Se consideraron 210 ejemplares de la especie. Se obtuvo un promedio de AD = 64,14 ± 13,18 cm; (rango 32-95 cm), y de PT = 8,36 ± 4,87 kg (rango 0,80-24,50 kg) y proporción sexual de (2,26♀: 1♂) (χ2 = 31,71; P < 0,05), por lo que se presume una segregación espacial de hembras y machos en la zona. La relación talla-peso fue significativa (P < 0,0001), y diferentes para cada sexo ♀: PT(kg) = [(0,00027)x(AD(cm)2,46)]; ♂: PT(kg) = [(0,00035)×(AD(cm)2,34)]. El valor K mostró divergencia entre sexos en noviembre y diciembre. La CPUE se estimó en 4,88 ind/1000 anzuelos. Se compararon estos resultados con investigaciones previas en la región sur del Caribe y se recomiendan mayores estudios de la especie en esta zona.<hr/>ABSTRACT. The longnose stingray (Dasyatis guttata) is a target species in the artisanal fisheries of the southern Gulf of Venezuela. Despite its economic importance, nowadays, studies about its status are lacking. During six continuous months (18 working days in total), we followed the artisanal fishery activities from Zapara Island, and evaluated morphometric characteristics, sex ratio, and the capture per unit effort (CPUE/ind/1000 hooks) of D. guttata. Biological sampling included: disc widths (AD), body mass total (PT), and sex. Using statistical analysis we assessed: a) the length-weight relationships by sex, b) monthly body condition, using the Fulton Index (K), and c) the CPUE. We evaluated 210 individuals of D. guttata. The mean values of our results were: AD = 64.14 ± 13.18cm (range 32-95 cm); PT = 8.36 ± 4.87 kg (range 0.8024.50 kg). The sexual proportion was (2.26♀: 1♂) (χ2 = 31.71; P < 0,05); hence we presume a spatial segregation occurred between females and males in the studied area. Length-weight relationship was statistically significant (P < 0.0001), and also varied according to the sex ♀: PT(kg) = [(0.00027)×(AD(cm)246)]; ♂: PT(kg) = [(0.00035)x(AD(cm)2.34)]. The K value showed differences between sexes during November and December. We obtained a CPUE of 4.88 individuals/1000 hooks. We compared our findings with previous research carried out in the southern Caribbean. Further research about this species in the area is recommended. <![CDATA[<b>Abundancia y diversidad de la ictiofauna en la Reserva de la Biósfera Los Petenes, Campeche, México</b>: <b>asociaciones con los ciclos nictimerales y las épocas climáticas</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200007&lng=es&nrm=iso&tlng=es RESUMEN. La porción marino litoral de la Reserva de la Biosfera Los Petenes (RBLP), en el estado mexicano de Campeche integra diversos componentes ecológicos estructurales entre los que destacan los peces como la macrofauna acuática más abundante y diversa. El estudio de la estructura y funcionamiento de los peces marinos costeros está condicionado por la comprensión de la dinámica ambiental de diferente escala. En el presente estudio, se realizaron muestreos nictimerales en tres momentos del año 2009 en un sitio localizado en la región central de la RBLP con el objetivo de describir las variaciones ambientales y los cambios en la abundancia y diversidad de la ictiofauna y discutir sus asociaciones con los ciclos día-noche y las épocas climáticas de Nortes, Secas y Lluvias. Los resultados muestran diferencias significativas en el comportamiento ambiental entre las tres épocas climáticas, pero no así entre las horas de día y de noche. Se determinaron 31 especies distribuidas en 17 familias entre las cuales se destaca Haemulidae, Sparidae, Lutjanidae, Sciaenidae, Monacanthidae y Tetraodontidae por su riqueza específica. Se identificaron 12 especies dominantes siendo las más abundantes Haemulonplumierii, Lagodon romboides, Orthopristis chrysoptera y Eucinostomus gula. La mayor abundancia se registró en la época climática Nortes y la menor en Secas. En Secas, además se observaron las mayores diferencias entre día y noche. Las especies dominantes se asociaron en dos grupos que coinciden por su abundancia en horas del día y la noche, y con la variabilidad ambiental.<hr/>ABSTRACT. In the Mexican state of Campeche, the marine littoral portion of Los Petenes Biosphere Reserve (RBLP), integrates several ecological components such as the fish community as the more diverse and abundant aquatic macrofauna. The coastal marine fish structure and function is conditioned by the comprehension of the environmental dynamic in different scale. In the present study, nycthemeral samplings were carried out in three moments of year 2009 in a site located in the central region of the RBLP with the objective of describing environmental patterns and changes in abundance and diversity of the ichthyofauna and discuss their associations with the day-night cycles and with the times of cold fronts "nortes", dry and rain. The results show significant differences in the environmental behavior between the three climatic seasons but not between the day hours and the night hours. 31 species were identified, including the families Haemulidae, Sparidae, Lutjanidae, Sciaenidae, Monacanthidae and Tetraodontidae by their species richness. Twelve species were identified dominant being the most abundant Haemulon plumierii, Lagodon rhomboides, Orthopristis chrysoptera and Eucinostomus gula. The highest abundance was recorded in "nortes" climatic season and the lowest in "dry" one and in the latter ones were observed the greatest differences between day and night. The dominant species were associated in two groups that match by its abundance in hours of the day and of the night and with environmental variability. <![CDATA[<b>Three-dimensional connectivity in the Gulf of California</b>: <b>an online interactive webpage</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200008&lng=es&nrm=iso&tlng=es This paper presents an online interactive webpage [http://connectivity-dispersion.cicese.mx/] that provides users with results of both the three-dimensional connectivity and spatial dispersion of particles in the Gulf of California (GC). These results were originated by means of a three-dimensional numerical model of circulation adapted to the GC from which the advection of particles were generated between different regions of the gulf. Particle connectivity and dispersion results were generated for and are limited to temporal scales to seasonal tides, which may aid in the interpretation of larval connectivity and contaminants within the gulf. <![CDATA[<b>Structure and temporal dynamic of tropical turf-forming macroalgal assemblages of the western coast of Mexico</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200009&lng=es&nrm=iso&tlng=es The study of the structure and dynamics of assemblages of benthic organisms has gained interest in recent decades because it can account for the influence of anthropogenic activities in the coastal zone and be incorporated into management and conservation plans. The region of Zihuatanejo, Mexico, has had an accelerated and unplanned urban development, negatively affecting coastal communities. However, studies on the structure and dynamics of algal assemblages, as well as some of the predominant physical factors in this region are scarce. The objective of this research was to carry out a preliminary study on the structure of macroalgal assemblages and their spatio-temporal variation in a depositional environment. The work was realized from June 2006 to December 2008 collecting randomly macroalgal samples and placing sediment traps on the bottom to characterize the deposition environment. The subtidal algal assemblages of the studied localities were predominantly turfs. The Detendred Correspondence Analysis showed that each locality had a particular species composition. The highest biomass was 37.82 ± 12.90 g dw m-2 and the lowest of 0-7.86 g dw m-2. The highest total sedimentation rate was 1818.10 ± 82.11 g dw m-2 day-1 and the lowest was 58.82 ± 8.75 g dw m-2 day-1. Significant differences were found in calcareous and articulated biomass, as well as in fine, coarse and total sedimentation rates among localities. The results obtained provide a basis for further research on the effects of sedimentation on the subtidal macroalgae assemblages of the study region. <![CDATA[<b>Spatial and temporal dynamics of virioplankton in a high-mountain tropical reservoir, El Neusa (Cundinamarca, Colombia)</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200010&lng=es&nrm=iso&tlng=es Temporal and spatial changes of virioplankton abundance (VLP), chlorophyll-a (Chl-a) concentration, and some environmental variables, were assessed from October 2004 to April 2005 at four sampling sites in a high-mountain reservoir in the Colombian Andes. VLP ranged from 2.4-10.5×10(7) and 3.66.5×10(7) VLP mL-1 in the samples from the photic zone and hypolimnion, respectively. Surface VLP showed a progressive increase from November to April in the limnetic zone, and until February in the littoral stations. This trend coincided with the gradual increase of the water column stratification, as well as the augment of the reservoir hydraulic volume. Principal components analysis showed a grouping of environmental (dissolved oxygen, pH, water temperature) and biological variables (VLP, Chl-a, bacterioplankton abundance and biomass) within the first component (26.4% of explained variance), associated to an increase of photosynthetic activity, as a potential supplement of organic substrates to heterotrophic viral hosts. High values of virus-to-prokaryote ratio (VPR), and a negative relationship between VLP and average biomass per prokaryotic cell, indicate strong viral control which is probably more intense on active and larger cells. These results provide a framework for understand the virioplankton responses to regional hydrological conditions and hydraulic behavior of this reservoir. The spatiotemporal scale of this study does not allow to confirm that viral dynamics is significantly affected by human activities causing potential alterations on nutrient cycling. <![CDATA[<b>Influence of the oceanographic dynamic in size distribution of cephalopod paralarvae in the southern Mexican Pacific Ocean (rainy seasons 2007 and 2008)</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200011&lng=es&nrm=iso&tlng=es The southern Mexican Pacific Ocean presents seasonal changes related to the rainy season and Tehuano winds, which generate mesoscale processes affecting biological productivity and marine biodiversity. Size distributions of squid paralarvae collected in this region during the rainy season (July 2007 and May-June 2008) were analyzed in relation to regional oceanography. Samples were collected through oblique hauls, and CTD casts were used to determine the structure of the water column. Between surveyed periods, there were no significant changes in the water temperature at 10 m, but there were significant variations in the mixed layer depth (MLD). The number of taxa, community composition and total abundance of paralarvae were similar between periods. However, in July paralarvae ≤2.0 mm were distributed along the margins of cyclonic and anticyclonic eddies associated with high temperatures. In May-June, the MLD and high concentrations of chlorophyll-a (Chl-a) determined the presence of a group of oceanic paralarvae and another of coastal paralarvae, separated by an upwelling front. The percentage of recently spawned paralarvae (≤2.0) nearly doubled during this period as a result of increased coastal sampling and high concentrations of Chl-a, indicating a coupling of adult reproduction with regional productivity. In the absence of winds, the mesoscale oceanographic complexity generates gradients and a differential effect on the distribution, transport and survival of cephalopod paralarvae. <![CDATA[<b>Characterization of the intestinal microbiota of wild-caught and farmed fine flounder (<i>Paralichthys adspersus</i>)</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200012&lng=es&nrm=iso&tlng=es A comparative analysis of the cultivable intestinal microbiota of farmed (AF) and wild-caught (WF) Paralichthys adspersus was performed. The 16S rRNA gene was used for taxa identification, and the ITS region for strain differentiation. We detected the presence of Vibrio, Bacillus, Photobacterium, Staphylococcus and Carnobacterium in AF, and Exiguobacterium, Klebsiella, Arthrobacter, Raoultella, Kluyvera, Myroides, Streptococcus, Vagococcus, Staphylococcus, Acinetobacter, Psychrobacter, Lactobacillus, Weissella and Lactococcus in WF. The microbial community was more diverse in WF than in AF. Some bacterial groups were only found in wild-caught fish and may be studied as potential beneficial agents for improving production traits in farmed fish. As the first study of microbiota of P. adspersus, it provides significant information that can potentially help improve farming practices by using strains as species-specific probiotics. <![CDATA[<b>Taxonomy of <i>Pinnotheres bipunctatus</i> Nicolet, 1849 with a distributional checklist of the Pinnotheridae of Chile and Peru, and a list of the Crustacea described by Hercule Nicolet in the Atlas of the Physical and Political History of Chile</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200013&lng=es&nrm=iso&tlng=es Because the male holotype of Pinnotheres bipunctatus possesses a carpus of the third maxilliped larger than the propodus, the dactylus disto-medially inserted on the ventral margin of this latter article extending far beyond its tip, and a laterally expanded telson, wider than the sixth abdominal somite, it is excluded from Pinnotheres and assigned to Pinnaxodes (type species P. chilensis). Although males of these species can morphologically be separated, the holotype of P. bipunctatus resembles a juvenile, consequently, a categorical taxonomic distinction between this species and P. chilensis will require a comparative morphological study of the preadult stages of the latter species. A distributional checklist and host of the Pinnotheridae recorded for the Peru-Chile region is included, along with a list and the taxonomic status of the five genera and 53 species of Crustacea described by Hercule Nicolet in the "Physical and Political History of Chile". <![CDATA[<b>Reproductive output of two benthic resources (<i>Fissurella latimarginata</i> and <i>Loxechinus albus</i>) under different management regimes along the coast of central Chile</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200014&lng=es&nrm=iso&tlng=es The biological and ecological benefits of fully and partially marine protected areas are well documented. However, the benefits reaching areas beyond the limits of the reserves are still emerging in spite the fact that they are essential for fishing grounds recovery and to gain support for the protection of the ocean among stakeholders. We analyzed the influence of protection on gonadosomatic index, and also body dry weight, of two economically and ecologically important species: the keyhole limpet, Fissurella latimarginata and the red sea urchin, Loxechinus albus, in order to determine the value of protected areas in directly enhancing reproduction, and therefore potential seeding on exploited areas. We compared two levels of protection in central Chile, determined by fisheries management regimes (in turn associated to fishing pressure): a) areas with fishing restrictions (low or none fishing effort; territorial use rights for fisheries and no-take areas) and b) open access areas (high exploitation rates). We also evaluated the independent influence of upwelling on both variables. Our results show for both species that a) body dry weight is not affected by management regime, b) management regime did not show a consistent impact on gonadosomatic index and c) upwelling did not affect the response variables. Our findings help disentangling the main factors determining reproductive patterns under contrasting human impact scenarios, suggesting that the selection of sites for establishing marine protected areas seems to be less relevant than efficient control of fishing effort and minimum legal size to assure natural seeding. <![CDATA[<b>Nitrogen and phosphorus in the subtropical Presidio River, northwestern Mexico</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200015&lng=es&nrm=iso&tlng=es The aim of this study was to assess its nitrogen and phosphorus concentrations in the Presidio River, because it receives large volumes of wastewater with high loads of detergents and fertilizers. The mean concentrations of total nitrogen and phosphorus determined between February 2008 and January 2009 were 640 and 167 μg L-1, respectively. The permissible phosphorous concentration established by the Official Mexican Standard NOM-001-SEMARNAT-1996 for pollutants discharge into rivers is 5000 μg L-1. However, according to international standards on phosphorous concentrations in continental water bodies, the Presidio River may be considered hypereutrophic. <![CDATA[<b>Evaluación de dietas comerciales en el crecimiento y su efecto en la composición bioquímica muscular de juveniles de chita, <i>Anisotremus scapularis </i>(Tschudi, 1846) (Familia: Haemulidae)</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200016&lng=es&nrm=iso&tlng=es Se evaluó el crecimiento, composición proximal y perfil de ácidos grasos muscular de juveniles de Anisotremus scapularis alimentados con cuatro dietas comerciales. Para este fin, durante 106 días, 200 peces fueron distribuidos en cuatro tratamientos; se alimentaron con dietas comerciales identificadas por su contenido proteico: 50% (DF-50), 48% (DM-48), 44% (DT-44) y 40% (DT-40). Las evaluaciones biométricas muestran que mayor crecimiento, conversión alimentaria y factor de condición se obtuvieron en A. scapularis alimentadas con la dieta DM-48 (P < 0,05). Sin embargo, la relación talla-peso y consumo de alimento-talla fueron similares entre los tratamientos dietarios. Por otro lado, menores concentraciones de proteína y mayores de lípidos se obtuvieron en el músculo de juveniles de A. scapularis alimentados con las dietas DM-48 y DF-50 (P < 0,05), respectivamente. El análisis de componentes principales mostró una mayor correlación entre peces alimentados con la dieta DM-48 y el contenido muscular de DHA, EPA y ARA; y con el crecimiento. Los resultados sugieren que la formulación de alimentos para juveniles de A. scapularis debería contemplar al menos de 48% de proteína y concentraciones importantes de DHA, EPA y ARA para su adecuado crecimiento de esta especie.<hr/>The growth, muscle proximal composition and fatty acid profile of juveniles of Anisotremus scapularis fed with four commercial diets were evaluated. During 106 days, 200 fishes, were distributed in four treatments, fish were fed with commercial diets identified by their protein content: 50% (DF-50), 48% (DM-48), 44% (DT-44) and 40% (DT-40). Biometric evaluations showed that higher growth (P < 0.05), feed-conversion and condition factor were obtained in A. scapularis fed with DM-48. However, both length-weight and food intake-size relationships were similar among dietary treatments. Lower (P < 0.05) protein and higher (P < 0.05) lipid concentrations in muscle of A. scapularis fed with DM-48 and DF-50 were obtained, respectively. Principal component analysis showed a higher correlation between fishes fed with DM-48 and DHA, EPA, and ARA muscle contents as with growth. Our results suggest that the food formulation for juveniles of A. scapularis should include at least 48% protein and significant concentrations of DHA, EPA and ARA for a proper growth of this species. <![CDATA[<b>Antibacterial effect of biosynthesized silver nanoparticles in Pacific white shrimp <i>Litopenaeus vannamei</i> (Boone) infected with necrotizing hepatopancreatitis bacterium (NHP-B)</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200017&lng=es&nrm=iso&tlng=es The shrimp necrotizing hepatopancreatitis is caused by a pleomorphic Gram-negative Rickettsia-like bacteria known as NHP-B. It is well known that silver is an effective bactericidal, but experiments with aquatic organisms are scarce, even more at nanoparticle level. The objective of this study was to determine the antibacterial effect of silver nanoparticles (AgNP) against NHP-B in the Pacific white shrimp Litopenaeus vannamei. For this, AgNO3 was used as source of silver, and extracts of dried leaves of green tea Camellia sinensis and neem tree Azadirachta indica as reducing agents. Different lots of infected shrimp received 0,5 and 35 μg of AgNP by forced feeding. The differences between the number of bacterial nodules in shrimp hepatopancreas and shrimp mortality relative to the amount of AgNP demonstrated to be effective against this pathogen. <![CDATA[<b>Uso de la zona de rompiente de playas arenosas por larvas de corvina (<i>Cynoscion</i> spp.), Provincia del Guayas, Ecuador</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200018&lng=es&nrm=iso&tlng=es La zona de rompiente de playas arenosas presenta una alta diversidad faunística y es criadero para peces y crustáceos. Las corvinas (Cynoscion spp.) son peces eurihalinos de importancia comercial y ecológica cuyas larvas usan las zonas de rompiente, sin embargo su biología es poco conocida. Se determinó el uso de zonas de rompiente estudiando la presencia, densidad y crecimiento de larvas de corvina en una playa arenosa ecuatoriana adyacente al sistema estuarino más grande del oeste de Sudamérica y se exploró las relaciones de estos tres factores con las variables ambientales analizadas. Se colectaron larvas de peces durante tres fechas en época húmeda, utilizando un trineo hiperbentónico y se analizaron sus otolitos. Las corvinas representaron el 58,6% de las larvas colectadas (densidad media = 8,97 ± 10,17 ind 100 m-2). El análisis de frecuencias de longitudes (2,3 a 7,9 mm longitud estándar, LE) determinó una distribución multimodal, sugiriendo que hubo varias cohortes de larvas que ingresaron a la playa habitándola durante varios días. La tasa de crecimiento reciente (últimos tres días) fue de 0,42 ± 0,12% mm LE día-1 y estuvo relacionada positivamente con la temperatura, oxígeno disuelto y densidades de corvina, sugiriendo que el número de corvinas en la zona de rompiente aumentó a medida que mejoran las condiciones para su crecimiento. Este estudio sugiere que las larvas de corvinas son las principales usuarias de la zona de rompiente de playas arenosas cercanas a desembocadura de ríos durante la época húmeda, donde ingresan por pulsos, atraídas por condiciones favorables para su crecimiento.<hr/>The surf zone of sandy beaches exhibits high faunal diversity and can be a nursery habitat for fish and crustacean. Croakers (Cynoscion spp.) are commercially and ecologically important euryhaline fishes whose larvae are found in the surf zone of sandy beaches; however, little is known about their biology. In this project, the use of surf zones was determined by studying the presence, density and growth of croaker larvae in an Ecuadorian surf zone adjacent to the largest estuarine system of western South America, and the relationship of these three factors with environmental variables explored. Fish larvae were collected during three days in the rainy season, using a hyperbenthic sledge and their otoliths analyzed. Croakers accounted for 58.6% of all larvae collected (mean density = 8.97 ± 10.17 ind 100 m-2). Size frequency distribution analysis (2.3 to 7.9 mm standard length, SL) resulted in a multimodal distribution, suggesting there were several cohorts of larvae that entered the surf zone and some inhabited the surf zone for several days. Recent larval growth rate (last three days) was 0.42 ± 0.12% SL day-1 and was positively related to water temperature, oxygen and croaker density, suggesting the number of croakers in the surf zone increased as growth conditions improved. Our study suggests that croaker larvae are the primary users of Ecuadorian surf zones adjacent to estuarine systems during the wet season, where they enter by pulses, attracted by better conditions for growth. <![CDATA[<b>Aspectos reproductivos de la lisa</b> <b><i>Mugil curema</i></b> <b>(Mugiliformes: Mugilidae) en la laguna costera de Barra de Navidad, Jalisco, México</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200019&lng=es&nrm=iso&tlng=es La lisa Mugil curema tiene amplia distribución en América, habitando sistemas costeros y estuarinos. Es un recurso con importancia pesquera en varias regiones del Pacífico mexicano. El objetivo del presente trabajo es describir aspectos reproductivos de M. curema durante un ciclo anual. Se realizaron muestreos mensuales con redes y atarraya de febrero 2011 a enero 2012 en la Laguna Barra de Navidad, Jalisco, México. Se analizaron 495 ejemplares, a los cuales se les midió la longitud y el peso total. De cada ejemplar se extrajeron las gónadas, se pesaron, clasificaron según su maduración y se procesaron para histología. Se capturaron ejemplares entre 10,3 y 38,5 cm, con promedio de 26,1 cm. Se identificaron 375 hembras con promedio de 27,2 cm y 110 machos con promedio de 23,4 cm. El número de hembras dominó de manera significativa en la muestra total, por mes y por clase de longitud. Los valores máximos del índice gonadosomático ocurrieron en abril, agosto y noviembre. El factor de condición presentó valores altos en varios meses coincidiendo en ambos sexos. En la ovogénesis se identificaron seis fases de desarrollo de los ovocitos y debido a la gran cantidad de ovocitos con crecimiento primario y en vitelogénesis 2 y 3, el patrón de desarrollo fue sincrónico por grupos con desove total. La longitud promedio de madurez (L50) de machos fue de 21,7 cm y de hembras de 24,5 cm. Contrastando estas dos últimas longitudes con las de captura, se sugiere que más del 50% de los organismos capturados son individuos que se reprodujeron al menos una vez.<hr/>The white mullet Mugil curema is broadly distributed in America inhabiting coastal and estuarine systems. It is an economically important fishery resource in several regions of the Mexican Pacific. The goal of this research was the description of several reproductive aspects of Mugil curema during an annual cycle. Fish were sampled monthly with gill and cast nets from February 2011 to January 2012 in the coastal lagoon Barra de Navidad, Jalisco, Mexico. A total of 495 fish were analyzed. Total length and weight were measured for each specimen and gonads were collected, weighted, classified after their maturation stage and preserved for histological analyses. Caught fish were between 10.3 and 38.5 cm total length with a mean of 26.1 cm. A total of 375 individuals were classified as females with a mean total length of 27.2 cm while 110 fish were classified as males with a mean total length of 23.4 cm. Females dominated by numbers in the total sample, monthly and by length classes. Highest values of the gonadosomatic index occurred in April, August and November. Condition factor showed high values in several months and its trend along the year was similar in both sexes. Six stages were identified during the oogenesis and, due to the high quantity of primary growth and secondary vitellogenic and tertiary vitellogenic oocytes, the developing pattern was group-synchronous with total spawning. Length at maturity (L50) was 21.7 cm for males and 24.5 for females. Comparing these values with length composition of commercial catches, more than 50% of caught fish have reproduced at least once. <![CDATA[<b>Use of otolith microchemistry as habitat indicator of <i>Anchoa tricolor</i> (Spix & Agassiz, 1829) in a subtropical estuary</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200020&lng=es&nrm=iso&tlng=es The objective of the present study was to evaluate the use of sagitta otolith microchemistry (Sr:Ca, Ba:Ca ratios) as habitat indicator of Anchoa tricolor between the estuary and the adjacent continental shelf. We analyzed 162 specimens of A. tricolor in the Paranaguá Estuarine Complex (Brazil), and salinity and rainfall data. The biological and environmental data were grouped into sectors (internal, intermediate, and external) and periods (early and late wet, and dry periods). The concentrations of Ca, Ba and Sr were determined using an ICP-OES. The Sr:Ca ratio indicated the existence of two groups, probably from different origins, that use the estuary at the same time, but occupying different sectors of the estuary. The Ba:Ca ratio did not differentiate the groups as to the use of estuary, but rather revealed low values, suggesting that this species does not use freshwater environments. However, this ratio showed a high variation in the wet period, indicating a greater availability of barium in the estuarine regions affected by the river discharge. Considering our results, it is possible to classify A. tricolor as an estuarine migrant species. Also, the Sr:Ca and Ba:Ca ratios can be indicative of the habitat use in a subtropical estuary. <![CDATA[<b>Growth and economic performance of diploid and triploid Pacific oysters <i>Crassostrea gigas</i> cultivated in three lagoons of the Gulf of California</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200021&lng=es&nrm=iso&tlng=es Diploid and triploid Crassostrea gigas oysters were cultivated at three farms (Guasave, Navolato and Ahome) in Sinaloa, Mexico, to evaluate their growth and economic performances. Growth rate and survival of oysters were compared in long-line cultivation and were mostly affected by water parameters rather than ploidy or their interaction. The highest growth rates for shell length (8.01 mm month-1) and body weight (9.08 g month-1) were obtained for the Ahome/triploid group. Survival differed significantly from 98.6% for the Guasave/triploids to 76.7% for the Ahome/diploids. After the first production cycle, more than 80% of production costs represent the purchase of cultivation equipment and salaries contributed with around 9%. The Guasave farm produced the highest profits (US$8,053.71 diploids, US$8,182.19 triploids). Use of diploids starting the production cycle on October-November to avoid mortality and improve final profit is recommended. <![CDATA[<b>First record of the smooth hammerhead shark (<i>Sphyrna zygaena</i>) in Saint Peter and Saint Paul Archipelago</b>: <b>range extension for the equatorial region</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200022&lng=es&nrm=iso&tlng=es A smooth hammerhead shark (Sphyrna zygaena) was found in Saint Peter and Saint Paul Archipelago in May 2015. This is the first confirmed occurrence of a smooth hammerhead shark in an equatorial oceanic island and suggests a geographic range extension for the species. <![CDATA[<b>Reproduction of Cortez oyster, <i>Crassostrea corteziensis</i> (Hertlein, 1951) in a growing area in the central Mexican Pacific coast</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200023&lng=es&nrm=iso&tlng=es The state of Nayarit is the main oyster producer in the Mexican Pacific, this derived from artisanal crops of Crassostrea corteziensis and collecting of wild seeds. Despite its importance, there are no studies on the reproduction of this species in Boca de Camichin, Nayarit, Mexico, which is the area with the highest production (around 90%). The aim of this study was to evaluate sex ratio, condition index (CI), reproductive cycle, and recruitment size for reproduction and its relationship with environmental factors. Sixty oysters were sampled monthly at La Palicienta Lagoon for one year. The organisms were weighed and measured, then fixed with 10% formalin for histological analyses. Subsequently, the gonads were processed by histology. Sex ratio was different from 1:1, with a predominance of females. The condition index (CI) was higher from March to July. Oyster spawning was most prevalent in May, August, and October. The temperature had a positive relationship with reproduction. Recruitment size at reproduction was 57.1 mm. The results of this study could supply useful information about reproduction of the species at La Palicienta and seed collection in Boca de Camichin, Nayarit. <![CDATA[<b>A glimpse to Laguna de los Cisnes, a field laboratory and natural monument in the Chilean Patagonia</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200024&lng=es&nrm=iso&tlng=es ABSTRACT. Laguna de los Cisnes (53°15'S) is a remote and unusual salty lagoon located in the Chilean Patagonia, declared natural monument to protect bird diversity in the area, which could also serve as a natural laboratory to monitor climate change. This study reports basic water, sediment and plankton characteristics observed during a summer (December) sampling, when the lagoon was hypersaline (51 g L-1), cold (9°C) and eutrophic, according to the high concentrations of phosphorous (0.30 ± 0.73 mg L-1), nitrate (0.66 ± 0.14 mg L-1) and chlorophyll-a (44.25 ± 2.52 μg L-1). The microalgae Spirogyra sp. and the micro-crustacean Artemia are predominating plankton. Results are discussed in the context of the climatic conditions affecting this lagoon year-round. <![CDATA[<b>The impact of <i>Neoechinorhynchus buttnerae</i> (Golvan, 1956) (Eoacanthocephala: Neochinorhynchidae) <i>outbreaks</i> on productive and economic performance of the tambaqui <i>Colossoma macropomum</i> (Cuvier, 1818), reared in ponds</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000200025&lng=es&nrm=iso&tlng=es ABSTRACT. This study evaluates the impact of Neoechinorhynchus buttnerae on the productive and economic performance of "tambaqui" reared in ponds. Two fish farms were selected, one with infected fish (IF) and the other with non-infected fish (NIF). Biometry, age, initial weight and handling data were collected from each studied specimen. Our results show that IF presented lower weight, evident loss of body mass and body deformities, reflecting on a condition factor 300% smaller than NIF. Infection by acanthocephalans caused an impact bigger than 200% on growth and affected the gross income directly, resulting in a difference higher than 1000% between IF and NIF farms. We conclude that this impact could be even greater if we consider both income decrease and raising production costs due to the parasite infection.