Aquatic insects and water quality in Peñas Blancas watershed and reservoir. The aquatic insects have been used to evaluate water quality of aquatic environments.The population of aquatic insects and the water quality of the area were characterized according to the natural and human alterations present in the study site. During the monthly-survey, pH, DO, temperature, water level, DBO, PO 4 and NO 3 were measured. Biological indexes (abundance, species richness and the BMWP-CR) were used to evaluate the water quality. No relation between environmental and aquatic insects was detected. Temporal and spatial differences attributed to the flow events (temporal) and the presence of Peñas Blancas reservoir (spatial). In the future, the investigations in Peñas Blancas watershed need to be focused on determining the real influence of the flows, sediment release and the possible water quality degradation because of agriculture activities. Rev. Biol. Trop. 59 (2): 635-654. Epub 2011 June 01.

The Volcán River watershed in the south Pacific of Costa Rica comprises forests, small urban settlements, cattle fields, and intensive agriculture (mostly pineapple and sugarcane). The ecological integrity and quality of its waters was assessed from 2011–2013 and 2018–2019 by means of physical–chemical parameters (pH, conductivity, temperature, DO, DBO, nitrate, total phosphorus, and pesticide residues) and benthic macroinvertebrate (MI) sampling in eight sites (Volcán, Cañas, and Ángel Rivers, and Peje and Maura streams), resulting in high ecological integrity in all sites except the Peje stream, which is polluted with nitrates and pesticides. Only in this stream was there a marked seasonal variation in the abundance of 16 MI families including Leptohyphidae, Leptophlebiidae, Philopotamidae, Glossossomatidae, and Corydalidae, among others, whose presence was limited exclusively to the dry season (December to April), disappearing from the stream in the rainy season, with corresponding peaks in nitrate (max 20.3 mg/L) and pesticides (mainly herbicides and organophosphate insecticides). The characteristics of the watershed, with large areas of forest and excellent water quality, allow for the re-colonization of organisms into the Peje stream; however, those organisms are incapable of development and growth, providing evidence of a contaminant-driven habitat fragmentation in this stream during the rainy season.

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Background. The climatic and geographic characteristics of Central Chile allow the concentration of high water demand from agricultural activities in low order rivers. Changes in the hydrologic regime of these rivers should affect the habitat availability of endemic benthic macroinvertebrates. However, the impact of water diversion in the Chilean rivers is poorly understood. Goals. We want to determine the effects of water abstraction in the habitat of benthic macroinvertebrates with biotic indices. Methods. We sampled nutrients, macroinvertebrates, and morphological characteristics of three rivers affected by agricultural water extractions in the Itata basin (Chile). We assess the habitat alteration and benthic macroinvertebrate assemblage through the measurement of depth, current velocity, Froude number, wetted width/depth ratio, dissolved oxygen, and biotic indices. Results. Traditional methods of constructing the weirs affect the water level in the sampling sites. Most of the habitat parameters shows variation between the control and impact sampling sections, but only Shannon and Simpson diversity indices were statistical different. Conclusions. The increase in taxonomical resolution of benthic macroinvertebrates in the Mediterranean zone of Chile could improve detection of environmental impacts of water extraction. We suggest the use of biological traits in order to determine specific relationships between water withdrawals and environmental changes in low order rivers of Chile affected by water extraction.

The nymph of Cloeodes dantasp. nov. is described from male and female nymphs collected from highland streams in the Caribbean Slope of the Costa Rica Central Volcanic Mountain Range. Adults are unknown. In addition, C. excogitatus and C. redactus are recorded for the first time in the country. Cloeodes dantasp. nov. can be differentiated from all described species by the predominantly brownish coloration on females and a similar coloration on males but with segments VII–IX light yellow and light brown, with no conspicuous marks or patterns; abundant scale-bases throughout most parts of the body; hindwings pads absent; the presence of three spines in the corners of the posterior margin of sternum III, and the posterior margin of tergum III with 28–30 spines on each side of the middle line (spine with a base width up to 0.5× spine length).

Las abejas a nivel ecosistémico juegan un papel clave en el desarrollo de la vida en el planeta. En la actualidad estos insectos se encuentran bajo amenaza por diversas prácticas antrópicas que afectan su hábitat. Para efectos de esta investigación se resalta la importancia de determinar la riqueza de especies de abejas meliponas (Meliponini) y su distribución espacial en el Corredor Biológico Montes del Aguacate como línea base para su conservación. Se establecieron cinco transectos en cinco localidades seleccionadas basados en el sistema de Zonas de Vida de Holdrige. Se recolectaron e identificaron dos especies de abejas meliponas con diferentes patrones en su distribución espacial y se establecieron rutas idóneas de vuelo para las especies recolectadas tomando como referencia la velocidad del viento para demostrar la importancia de la cobertura forestal.

The estuarine ecosystem of Laguna Madre de Dios (LMD), in the Caribbean coast of Costa Rica, is exposed to contamination with pesticide residues coming from the upstream agricultural areas. Biomarkers can provide a better indication of the tness of biota in real mixture exposure scenarios than traditional lethal dose toxicity measurements. Here, we measured biomarkers of biotransformation, oxidative stress and neurotoxicity on Astyanax aeneus, an abundant sh species in LMD. Glutathione Stransferase activity (GST), catalase activity (CAT), lipid peroxidation (LPO), and cholinesterase activity (ChE) were measured in sh collected during seven sampling campaigns, carried out between 2016 and 2018. Pesticide residues were analysed in surface water samples collected every time sh were sampled.Residues of 25 pesticides, including fungicides, insecticides and herbicides, were detected. The biomarkers measured in A. aeneus varied along the sampling moments, however, biotransformation and oxidative stress signals showed coupled responses throughout the assessment. Furthermore, signi cant correlations were established between three biomarkers (GST, LPO and CAT) and individual pesticides, as well as between GST and LPO with groups of pesticides with shared biocide action. Among pesticides, insecticide residues had a major in uence on the responses observed in sh. This work shows that the frequent exposure to environmentally relevant concentrations of pesticides can be related to physiological responses in sh that affect their health. This early warning information should be considered to improve the protection of estuarine ecosystems in the tropics.

Con el objetivo de evaluar la posible afectación del emisario submarino en la ciudad de Limón, sobre el medio marino circundante, se establecieron 6 estaciones de muestreo, 4 de ellas cercanas a la zona de desfogue y 2 controles; en cada una se tomaron muestras de agua a 0 m y 10 m durante el 2012-2013 para medir nutrimentos, parámetros fisicoquímicos, concentración de microalgas y cantidad de unidades formadoras de colonias (UFC) de Enterococcus. Se contrastó la abundancia algal entre las estaciones bajo influencia del emisario, sus controles y entre profundidades, con un análisis de similitud (ANOSIM); en los casos en que hubo diferencia significativa se procedió a realizar un análisis SIMPER para determinar las especies responsables. La abundancia fitoplanctónica se utilizó para jerarquizar la dominancia de especies mediante el diagrama de Olmstead y Tukey e incorporarlas en un análisis de correspondencia canónica. Se determinó que en la zona existe una marcada influencia de las lluvias sobre la concentración de los nutrimentos, silicato y ortofosfato, además de parámetros como el oxígeno disuelto y la salinidad. Las UFC se mantuvieron por debajo del límite máximo de 35 UFC/100 mL establecidos por la Agencia de Protección Ambiental de los Estados Unidos (USEPA). La diversidad fitoplanctónica fue alta y estuvo compuesta, principalmente, por especies cosmopolitas. Debido a que la concentración de nutrientes y UFC son bajas, junto con una alta diversidad algal, se concluye que no existe evidencia directa de un impacto negativo del emisario sobre la zona estudiada.