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Microplastics (MP) are a hazardous pollutant of global concern that threatens aquatic ecosystems and public health. We used the invasive, cosmopolitan, and environmentally versatile red swamp crayfish Procambarus clarkii as a model to study the effects of MP on the intestinal microbiome. Crayfish collected from the environment were compared with specimens exposed to recycled Polyethylene terephthalate (rPET) MP in feed (30%) for 96 h in the laboratory and a control group. We analyzed the 16S rRNA of the intestinal bacteria by PCR-DGGE and high-throughput sequencing. MP exposure caused dysbiosis of the intestinal microbiota, with an increase in Alphaproteobacteria and Actinobacteria. We detected higher abundance of opportunistic genera such as Klebsiella, Acinetobacter, Hydromonas, Pseudomonas, Gemmobacter, and Enterobacter on MP fed organisms. Moreover, MP exposure reduced the abundance of Clostridia and Bateroidetes, which are important for immune system development and pathogen prevention. Furthermore, MP exposure decreased the phenoloxidase (PO) immune response in crayfish. There was a significant difference in the richness of intestinal bacterial communities after consumption of food contaminated with MP, likely increasing the abundance of opportunistic bacteria in the intestinal microbiota. Our results suggest that MP alter the gut microbial composition and impair the health of P. clarkii.

RESUMO

Microplastic pollution represents a serious threat to coastal marine systems. We evaluated the presence of microplastics (MPs) in 168 specimens of six commercially exploited bivalve species in the Golfo de Nicoya, Costa Rica. MPs were present in 100 % of the specimens of Leukoma asperrima and L. ecuadoriana, 74 % of Mytella strigata, 82 % of M. guyanensis, 84 % of Asthenometis asthenodon, and 82 % of Tagelus affinis. When considering all specimens, we found on average 4.8 ±â€¯8.0 pieces per individual and 2.1 ±â€¯3.3 items g-1 of wet tissue. There were significant differences between species with L. asperrima and L. ecuadoriana containing the highest number of pieces. Fibers and particles comprised 92 % and 8 %, respectively. This is the first study from the Central America's Pacific region showing the presence of MPs in bivalve species.

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A redescription of Pagurus albus (Benedict, 1892) is presented together with a description of a new species of hermit crab, Pagurus pseudoalbus sp. n., from the Pacific coast of Costa Rica. Pagurus pseudoalbus sp. n. differs from P. albus and P. perlatus by the length of antennal acicles, which do not exceed the distal margin of the 4th antennal segment, whereas in the latter two species, the antennal acicles exceed the 4th antennal segment; the antennular peduncle is proportionally longer than the ocular peduncle in the new species compared to P. perlatus, but shorter than in P. albus; the palm of the right cheliped in P. pseudoalbus sp. n. is 1.3 times as long as broad, while in P. albus and P. perlatus it is 1.0 and 1.4 times as long as broad, respectively. Including the new species, the genus Pagurus in the Eastern Tropical Pacific currently includes 16 species.

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AbstractThere is a growing need to strengthen the small-scale fishing sector with emerging governance methods that improve fishers' threatened livelihoods. Therefore, this study's aim was to develop management recommendations, based on easily interpreted conclusions that can be used to address the socio-ecological difficulties that the artisanal, bottom-longline fishery in Bejuco, Pacific coast of Costa Rica faces. The results of previously recorded fisher socio-ecological perceptions and an evaluation of the spotted rose snapper's, Lutjanus guttatus, population dynamics were assigned a measurable set of indicators in reference to the fishery's natural, human and management sub-systems. This was done via the traffic light method with easily interpreted colors based on a review of similar published fisheries studies. According to these results, a stock assessment for the fishery's target species and research to determine the composition and magnitude of the fishery's discarded species were recommended. Fisher economic dependence on bottom-longline activities led to the recommendation to develop alternative livelihood strategies. Also, the promotion of alternative markets and sustainability certification strategies for the snapper fishery are advised. Enlargement of the multi-use marine protected areas within the fishery's grounds and improvement of their management strategies is also recommended. In order for this to occur, improved resource user coordination in the form of a fisher association that has the capability to lobby for increased enforcement of the protected areas from destructive fisheries must be realized. Doing so would aid the development of a local management plan and participatory governance system. Such an initiative would justify the development of community lead marine protected area management regimes.

ResumenExiste una creciente necesidad de fortalecer el sector de la pesca de pequeña escala con métodos de gobernanza emergentes que mejoren las estrategias de subsistencia de los pescadores. Por lo tanto, el presente estudio se centró en el desarrollo de recomendaciones de manejo, basadas en conclusiones fácilmente interpretables, que ayuden a atender las dificultades socio-ecológicas que enfrentan los pescadores artesanales que utilizan líneas de fondo en Bejuco, Pacífico de Costa Rica. Se asignó un conjunto medible de indicadores para cada sub-sistema (natural, humano y manejo) de la pesquería a partir de los resultados de un análisis previo de las percepciones socioecológicas de los pescadores y una evaluación de aspectos biológico-pesqueros para el pargo manchado Lutjanus guttatus. Se usó la técnica de semáforo con la cual se asignaron colores para la evaluación de indicadores construidos con base en la revisión de literatura publicada. Se propusieron recomendaciones de manejo basadas en los resultados. Se sugiere un análisis del estado del stock de la principal especie objetivo de pesca y un estudio que determine la magnitud y composición de las especies descartadas. Debido a la alta dependencia económica de los pescadores, se recomienda la implementación de programas que permitan el desarrollo de opciones alternativas del empleo. Además, se recomienda promover mercados alternativos y sistemas de certificación sostenible para la captura de pargo manchado. También se recomienda la ampliación de las áreas marinas protegidas de uso múltiple de la zona. Para esto es necesario mejorar la coordinación y participación de los usuarios mediante la formación de una asociación que tenga la capacidad de vincular a la contraparte gubernamental en la solución de múltiples limitaciones y problemas (p. ej pesca ilegal) en la actividad pesquera de Bejuco.Esto facilitaría la construcción de un plan de manejo local bajo un sistema de gobernanza participativa.

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Nest site selection for individual leatherback sea turtles, Dermochelys coriacea, is a matter of dispute. Some authors suggest that a female will tend to randomly scatter her nests to optimize clutch survival at a highly dynamic beach, while others suggest that some site fidelity exists. It is also possible that both strategies exist, depending on the characteristics of each nesting beach, with stable beaches leading to repeating nest site selections and unstable beaches leading to nest scattering. To determine the strategy of the Tortuguero population of D. coriacea, female site preference and repetition were determined by studying whether females repeat their nest zone choices between successive attempts and whether this leads to a correlation in hatching and emergence success of subsequent nests. Nesting data from 1997 to 2008 were used. Perpendicular to the coastline, open sand was preferred in general, regardless of initial choice. This shows a tendency to scatter nests and is consistent with the fact that all vertical zones had a high variability in hatching and emergence success. It is also consistent with nest success not being easily predictable, as shown by the lack of correlation in success of subsequent nesting attempts. Along the coastline, turtles showed a preference for the middle part of the studied section of beach, both at a population level and as a tendency to repeat their initial choice. Interestingly, this zone has the most artificial lights, which leads to slightly lower nest success (though not significantly so) and hatchling disorientation. This finding merits further study for a possibly maladaptive trait and shows the need for increased control of artificial nesting on this beach.

La selección de sitio de anidación por parte de individuos de la tortuga baula, Dermochelys coriacea, es tema de discusión. Algunos autores sugieren que una hembra dispersa sus nidos al azar para maximizar su éxito en las inestables playas que elige para anidar, mientras que otros sugieren que existe cierta fidelidad al sitio de anidación. También es posible que ambas estrategias existan, dependiendo de las características de la playa donde anidan, así playas estables llevarían a las hembras a repetir la selección de sitio mientras que las playas inestables las llevarían a dispersar sus nidos. Para determinar la estrategia que usan las hembras de D. coriacea de Tortuguero, se estudió la preferencia de sitio de las hembras así como su repetición en este sitio, desde 1997 hasta 2008. Para la selección de sitio vertical (perpendicular a la costa), las hembras en general prefirieron anidar en arena abierta, independientemente de su escogencia inicial. Esto muestra una tendencia a dispersar los nidos y es consistente con la alta variación en los éxitos de eclosión en todas las zonas, así como la falta de relación entre los éxitos de eclosión de nidos subsecuentes, lo cual muestra que el éxito de los nidos no es predecible. Para la selección horizontal (a lo largo de la costa) se prefirió la parte media de la sección estudiada de la playa, tanto a nivel poblacional como individual (repetición de selección de sitio). Interesantemente, esta zona tiene la mayor cantidad de luces artificiales lo cual lleva a éxitos de eclosión ligeramente más bajos (aunque no significativamente) y a la desorientación de neonatos. Este resultado amerita estudios futuros para determinar si se trata de una tendencia maladaptativa en la población y muestra la importancia de controlar la cantidad de luz artificial en esta playa como medida de conservación.

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The mangrove crab Aratus pisonii (H. Mile Edwards, 1837) was considered to have an amphi-American distribution but a recent genetic study revealed that the Eastern Tropical Pacific populations represent a new species, A. pacificus (Thiercelin & Schubart, 2014). These sister species separated by the Central American Isthmus have developed under different environmental conditions that may influence their larval development. A comparison of morphological and morphometric features (length and width of cephalothorax and length of rostral and dorsal spine, antenna, antennule, telson, and furcae) of recently-hatched larvae of A. pacificus (Pacific coast) and A. pisonii (Caribbean coast) from Costa Rica revealed that the setation pattern of the antennules differed between the species and the analyzed morphometric features were larger in A. pisonii larvae. Difference in size may be a response to different environmental conditions, as the lower primary production in coastal Caribbean waters, which may have forced females of A. pisonii to allocate more energy into the offspring, resulting in larger zoeal size. A greater endogenous reserve may allow the larvae to reduce the duration of the planktonic phase and increase the size at metamorphosis, thus enhancing their survival chances during the planktonic phase. These data regarding morphological and morphometric differences in recently-hatched larvae of the Pacific and Caribbean species support the conclusion that specimens of Aratus from both coasts of Costa Rica represent indeed different species.

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The taxonomy and geographic distribution of the freshwater crabs of the family Pseudothelphusidae Ortmann, 1893, of Costa Rica, Central America, particularly of the genus Ptychophallus Smalley, 1964, are revised. Historical materials deposited in major collections of several institutions were examined, as well as valuable collections in the Zoological Museum of the University of Costa Rica that include abundant specimens obtained recently (2007-2010) in the southern region of the country. The pseudothelphusids of Costa Rica consists of 15 currently valid species belonging to Achlidon Smalley, 1964 (two species), Allacanthos Smalley, 1964 (two species), Potamocarcinus H. Milne Edwards, 1853 (three species), and Ptychophallus (eight species). Two species seem to be restricted to the Atlantic drainage, while seven are known only from the Pacific drainage; six species occur in both drainages. Ptychophallus comprises 13 valid species; four new synonymies are proposed: P. osaensis Rodríguez, 2001, P. campylus Pretzmann, 1968, P. tumimanus ingae            Pretzmann, 1978, and P. barbillaensis Rodríguez & Hedström, 2001, as junior synonyms of P. paraxantusi (Bott, 1968), P. tristani (Rathbum 1896), P. tumimanus (Rathbun, 1898), and P. uncinatus Campos & Lemaitre, 1999, respectively. Two species, P. colombianus (Rathbun, 1896) and P. exilipes (Rathbun, 1898), are considered species inquerendae. Lectotype designations are made for P. montanus and P. colombianus. Three species of Ptychophallus are known exclusively from Costa Rica, five exclusively from Panama, and five species occur in both countries; one species appears to be exclusive of the Atlantic drainage, whereas five are known only from the Pacific drainage and seven occur in both drainages. The gonopod morphology of all species is redescribed and illustrated, and maps of their geographic distribution are furnished. A key to the species of Pseudothelphusidae from Costa Rica and to all species of Ptychophallus is provided. 

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The closure of the Isthmus of Panama (about 3.1 million years ago) separated previously continuous populations and created two groups of extant species, which live now in the Pacific and Atlantic drainage systems. This relatively recent event was a trigger to diversification of various species in the Neotropics, nonetheless there are exemplars that do not show sufficient morphologic variability to separate them by traditional morphological tools. About 60 years ago, some freshwater decapod species with high morphological similarity were separate by previous researchers, based on geographical distribution, in Pacific and Atlantic and considered as "sister species". However, the complete isolation of these prawns by this geographical barrier is questionable, and it has generated doubts about the status of the following transisthmian pairs of sibling species: Macrobrachiumoccidentale × Macrobrachiumheterochirus, Macrobrachiumamericanum × Macrobrachiumcarcinus, Macrobrachiumdigueti × Macrobrachiumolfersii, Macrobrachiumhancocki × Macrobrachiumcrenulatum, Macrobrachiumtenellum × Macrobrachiumacanthurus and Macrobrachiumpanamense × Macrobrachiumamazonicum. Here we evaluated the relation among these pairs of sibling species in a molecular phylogenetic context. We generated 95 new sequences: 26 sequences of 16S rDNA, 25 of COI mtDNA and 44 of 18S nDNA. In total, 181 sequences were analyzed by maximum likelihood phylogenetic method, including 12 Macrobrachium transisthmian species, as well as seven other American Macrobrachium species, and two other palaemonids. Our analysis corroborated the morphological proximity of the sibling species. Despite the high degree of morphological similarities and considerable genetic diversification encountered among the transisthmian sister species, our data support the conclusion that all species included in sibling groups studied herein are valid taxonomic entities, but not all pairs of siblings form natural groups.

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Caridean shrimps are a highly diverse group and many species form symbiotic relationships with different marine invertebrates. Periclimenesrathbunae is a brightly colored shrimp that lives predominantly in association with sea anemones. Information about the reproductive ecology of the species is scarce. Therefore, we collected 70 ovigerous females inhabiting the sun sea anemone Stichodactylahelianthus in coral reefs from the southern Caribbean coast of Costa Rica. Females produced on average 289 ± 120 embryos. The volume of recently-produced embryos was on average 0.038 mm(3), and embryo volume increased by 192% during the incubation period. The average embryo mortality during embryogenesis was 24%. The reproductive output was 0.24 ± 0.094, considerably higher than in many other pontoniine shrimps. Females carrying embryos close to hatching showed fully developed ovaries, suggesting consecutive spawning. We assume that the sheltered habitat, living on sea anemones, allows Periclimenesrathbunae to allocate more energy in embryo production than most other free-living caridean shrimps. This is the first record of Periclimenesrathbunae for Costa Rica.

RESUMO

Caridean shrimps of the genus Synalpheus are abundant and widely distributed in tropical and subtropical regions, but knowledge of their reproductive biology remains scarce. We report reproductive traits of Synalpheusapioceros from Bocas del Toro, Panama, based on collections in August 2011. The 46 ovigerous females that were analyzed ranged in size from 3.8 to 7.4 mm in carapace length. Fecundity varied between 8 and 310 embryos and increased with female size. Females invested 18.6 ± 10.3% of their body weight in Embryo production. Embryo volume increased considerably (77.2%) during embryogenesis, likely representing water uptake near the end of incubation period. Compared to Synalpheus species with abbreviated or direct development, Synalpheusapioceros produced substantially smaller embryos; however, Synalpheusapioceros seems to have a prolonged larval phase with at least five zoeal stages, which may explain the combination of relatively small and numerous embryos. We did not find nonviable, minute, chalky embryos, previously reported for Synalpheusapioceros specimens obtained from the northwestern Gulf of Mexico, which supports the hypothesis that the production of this type of embryos may be a physiological response of this warm-water species to the temperature decrease near to its latitudinal range limit.

ResumenAunque los camarones carídeos del genero Synalpheus son muy abundantes y se encuentran ampliamente distribuidos en regiones tropicales y subtropicales, el conocimiento sobre su biología reproductiva es escaso. En este estudio reportamos algunas características reproductivas de especímenes de Synalpheusapioceros de Bocas del Toro, Panamá, colectados en Agosto del 2011. El largo del caparazón de las 46 hembras ovígeras analizadas se encuentra en un rango de 3.8 y 7.4 mm. La fecundidad varió entre 8 y 310 huevos, aumentando con el tamaño de la hembra. Las hembras invirtieron 18.6 ± 10.3% de su peso corporal en la producción de huevos. El tamaño de los huevos aumentó considerablemente (77.2%) durante la embriogénesis, probablemente por la absorción de agua al final del periodo de incubación. Comparado con especies de Synalpheus que presentan desarrollo abreviado o directo, Synalpheusapioceros produce huevos considerablemente más pequeños; sin embargo Synalpheusapioceros parece tener una fase larval prolongada, con al menos cinco estadios larvales, lo que podría explicar que los huevos sean relativamente pequeños y numerosos. No encontramos los huevos anómalos, no viables, que previamente se habían reportado para especímenes obtenidos en el Golfo de México, lo cual apoya la hipótesis de que la producción de este tipo de huevos puede ser una respuesta fisiológica a la disminución de temperatura cerca del límite latitudinal de esta especie habitante de aguas cálidas.