Multi-gene phylogeny of the primary freshwater crab genus Ptychophallus Smalley, 1964 (Pseudothelphusidae: Ptychophallinae) from the Neotropical region.

The diversity of primary freshwater crabs of Central America is underestimated and poorly known, specially when considering both Atlantic and Pacific drainages distribution. Among the family Pseudothelphusidae Ortmann, 1893, the genus Ptychophallus Smalley, 1964 was recently revised using morphological data and encompassing 14 valid species, which are distributed exclusively in Costa Rica and Panama. Despite the informative scenario constructed with this previous study, some uncertainties remained such as those related to the populations distributed along different drainages and the lack of complete information regarding the phylogenetic relationships among the species that belong to this genus. Our phylogenetic reconstruction based on multigenes revealed four lineages. Ptychophallus costaricensis, P. colombianus, P. lavallensis, P. montanus, and P. tumimanus are well-established species, while P. paraxanthusi, P. exilipes and P. tristani were recovered as non-monophyletic in some relationships. Ptychophallus tristani and P. paraxanthusi were determined to be close relatives one with other, but with some representatives showing no clear correspondence and positioning in the molecular phylogeny, which raised doubts about the validity as separate species and/or the accuracy of identifications for some GenBank sequences. Ptychophallus tumimanus and P. montanus are morphologically very similar, but they are positioned in distinct clades. The genetic results confirmed a previous proposal that P. barbillaensis is a junior synonym of P. uncinatus, and P. bilobatus is closely related to P. uncinatus. The findings revealed the presence of one peculiar lineage with one species from Costa Rica compound by the resurrected P. campylus and another species from Costa Rica, originally identified as "P. cf. exilipes"; its morphology, however, did not match with any other analyzed species, which requires further analysis. Finally, possible misidentification in some sequences deposited in the GenBank were detected and should be reviewed. The reconstructed molecular phylogeny for the genus that inhabits both Atlantic and Pacific drainages of Central America provides a better understanding of the knowledge on the evolution of freshwater crabs and represents key information that will serve as baseline for further taxonomic studies on the cryptic biodiversity of this group.

Bio-inspired design of hard-bodied mobile robots based on arthropod morphologies: a 10-year systematic review and bibliometric analysis.

This research presents a 10-year systematic review based on bibliometric analysis of the bio-inspired design of hard-bodied mobile robot mechatronic systems considering the anatomy of arthropods. These are the most diverse group of animals whose flexible biomechanics and adaptable morphology, thus, it can inspire robot development. Papers were reviewed from two international databases (Scopus and Web of Science) and one platform (Aerospace Research Central), then they were classified according to: year of publication (January 2013 to April 2023), arthropod group, published journal, conference proceedings, editorial publisher, research teams, robot classification according to the name of arthropod, limb's locomotion support, number of legs/arms, number of legs/body segments, limb's degrees of freedom, mechanical actuation type, modular system, and environment adaptation. During the screening, more than 33000 works were analyzed. Finally, a total of 174 studies (90 journal-type, 84 conference-type) were selected for in-depth study: Insecta - hexapod (53,8%), Arachnida - octopods (20.7%), Crustacea - decapods (16,1%), and Myriapoda - centipedes and millipedes (9,2%). The study reveals that the most active editorials are the Institute of Electrical and Electronics Engineers Inc., Springer, MDPI, and Elsevier, while the most influential researchers are located in the USA, China, Singapore, and Japan. Most works pertained to spiders, crabs, caterpillars, cockroaches, and centipedes. We conclude that "arthrobotics" research, which merges arthropods and robotics, is constantly growing and includes a high number of relevant studies with findings that can inspire new methods to design biomechatronic systems.

Microplastics in feed cause sublethal changes in the intestinal microbiota and a non-specific immune response indicator of the freshwater crayfish Procambarus clarkii (Decapoda: Cambaridae).

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.

Presence of microplastics in six bivalve species (Mollusca, Bivalvia) commercially exploited at the Pacific coast of Costa Rica, Central America.

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.

Description of a new species of Pagurus Fabricius, 1775 (Crustacea: Paguroidea: Paguridae) from the Pacific coast of Costa Rica, Central America, with notes on Pagurus albus (Benedict, 1892).

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.

Stomach content analyses of the threadfin anglerfish Lophiodes spilurus (Lophiiformes: Lophiidae) associated with deepwater shrimp fisheries from the central Pacific of Costa Rica.

Our knowledge of deepwater ecosystems along the Pacific of Central America is extremely limited. We analyzed the diet composition of 200 adult specimens of Lophiodes spilurus ranging in size from 7.8 to 17.8 cm total length (TL). Samples were obtained from deep bottom trawls (depth: 105-238 m) along the central Pacific of Costa Rica. We calculated the percentage of number (% N), weight (% W), and occurrence (% O) of each food item encountered in the stomachs; based on this information, the Index of Relative Importance (IR) was calculated. Moreover, we estimated diet overlap for three different size classes (<10.1, 10.1-15.0 and > 15.1 cm TL). The results revealed exclusively two groups of benthic prey items: crustaceans (30%) and teleost fish (70%) in their diet. The most frequent preys were pandalid shrimps Plesionika trispinus (% O = 17) and the fathom mora Physiculus rastrelliger (% O = 12). The greatest diversity and frequency of abundance of food items was observed in intermediate-sized individuals (10.1-15.0 cm TL). Small-sized L. spilurus (< 10.1 cm TL) fed mainly on teleost fish, while larger (> 15.0 cm TL) preyed on large-sized stomatopods and teleost fish. There was a clear diet overlap between small and intermediate-sized L. spilurus (p < 0.05). However, differences in diet-overlap were not detected in small and large-sized individuals or intermediate and large-sized specimens (p > 0.05). Our results suggest that L. spilurus feeds exclusively on crustaceans (Decapoda and Stomatopoda) and benthic teleost fish along the Pacific of Costa Rica. While small and large-sized individuals showed a more pronounced selectivity for certain prey items, the high diversity of benthic prey items observed in intermediate-sized specimens suggest a more opportunistic foraging behavior.

Morphological and morphometric comparison of the first zoeal stage of the mangrove crabs of the genus Aratus H. Milne Edwards, 1853 (Decapoda: Sesarmidae).

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.

Taxonomy of the freshwater crabs of Costa Rica, with a revision of the genus Ptychophallus Smalley, 1964 (Crustacea: Decapoda: Pseudothelphusidae).

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. 

Preliminary survey of a nemertean crab egg predator, Carcinonemertes, on its host crab, Callinectesarcuatus (Decapoda, Portunidae) from Golfo de Nicoya, Pacific Costa Rica.

The possible presence of egg predators in brood masses of portunid crabs from Pacific Central America has not been studied yet. This survey reports the finding of a nemertean crab egg predator on the portunid crab, Callinectesarcuatus, from the Golfo de Nicoya, Pacific Costa Rica. Nemerteans were found in the egg masses of 26 out of the 74 crabs for a prevalence of 35%. The intensity (mean number of worms/ infected crab) was estimated to be 18 with a variance of 1-123 worms/infected crab. No nemerteans were observed either in the 19 Callinectesarcuatus from Golfo Dulce (southern Pacific coast) and the 10 Portunusasper from Herradura-Jaco (central Pacific coast). This nemertean is a member of the genus Carcinonemertes, which has been reported from the Caribbean coast of Panama. However, the encountered Carcinonemertes sp. is the first published finding and report from Costa Rica and Pacific Central America.

Reproductive traits of the symbiotic pea crab Austinotheresangelicus (Crustacea, Pinnotheridae) living in Saccostreapalmula (Bivalvia, Ostreidae), Pacific coast of Costa Rica.

Pea crabs of the family Pinnotheridae exhibit a symbiotic life style and live associated with a variety of different marine organisms, especially bivalves. Despite the fact that pea crabs can cause serious problems in bivalve aquaculture, the available information about the ecology of these crabs from Central America is extremely limited. Therefore, the present study aimed to describe different reproductive features of the pinnotherid crab Austinotheresangelicus associated with the oyster Saccostreapalmula in the Golfo de Nicoya, Pacific coast of Costa Rica. Monthly sampling was conducted from April to December 2012. Average carapace width (CW) of the 47 analyzed ovigerous females was 7.62 mm. The species produced on average 2677 ± 1754 recently -extruded embryos with an average volume of 0.020 ± 0.003 mm(3); embryo volume increased during embryogenesis by 21%, but did not vary significantly between developmental stages. Brood mass volume varied greatly (between 11.7 and 236.7 mm(3)), and increased significantly with female CW. Females invested on average 76.7% (minimum: 21.7%; maximum: 162.8%) of their body weight in brood production, which confirms a substantially higher energy allocation for embryo production in pinnotherid crabs compared to free-living decapods.

Molecular perspective on the American transisthmian species of Macrobrachium (Caridea, Palaemonidae).

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.

Reproductive biology of the sea anemone shrimp Periclimenesrathbunae (Caridea, Palaemonidae, Pontoniinae), from the Caribbean coast of Costa Rica.

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.

Embryo production in the sponge-dwelling snapping shrimp Synalpheusapioceros (Decapoda, Alpheidae) from Bocas del Toro, Panama.

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.

Indicator-based management recommendations for an artisanal bottom-longline fishery in Costa Rica, Central America / Recomendaciones de manejo basadas en indicadores para la pesca artesanal con líneas de fondo en Costa Rica, Centroamérica

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.

Nest site selection by individual leatherback turtles (Dermochelys coriacea, Testudines: Dermochelyidae) in Tortuguero, Caribbean coast of Costa Rica / Selección del sitio de anidación de individuos de tortuga baula (Dermochelys coriacea, Testudines: Dermochelyidae) en Tortuguero, costa Caribe de Costa Rica

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.

Population biology of the burrowing shrimp Callichirus seilacheri (Decapoda: Callianassidae) in northern Chile

La historia natural de los camarones fantasma, conocidos por modelar la estructura de las comunidades en hábitats de aguas someras, ha sido poco estudiada en el Pacífico suramericano. Aquí presentamos información ecológica concerniente a Callichirus seilacheri, con base en individuos recolectados entre enero y diciembre de 2003 en playa Las Machas, norte de Chile. La densidad de las madrigueras varió entre 1.4 y 20.2 madrigueras / 0.25 m2, y fue mayor durante el verano (18.2 madrigueras / 0.25 m2). La proporción de sexos fue 1:1 durante la mayor parte del periodo de estudio; sin embargo, las hembras superaron en número a los machos en enero y setiembre. Los machos presentaron un tamaño máximo mayor al de las hembras (27.1 y 24.0 mm CL, respectivamente). La presencia de juveniles se restringió principalmente al periodo comprendido entre febrero y mayo. La madurez sexual se alcanza a un tamaño de CL de 20.8 mm en los machos y 18.1 mm en las hembras. El periodo reproductivo principal se extendió del otoño al invierno (de mayo a agosto, con un pico en junio), y coincidió con temperaturas decrecientes en el agua y con la presencia de una capa de sedimento sobre las madrigueras.

The life history of ghost shrimps, known for their role in shaping community structures in shallow water habitats, is poorly studied in species occurring along the coasts of the South American Pacific. Here we present ecological information concerning Callichirus seilacheri based upon individuals collected from January to December 2003 in Las Machas beach, northern Chile. Burrow densities varied between 1.4 and 20.2 burrows / 0.25 m2, and was highest during summer (18.2 burrows / 0.25m2). The sex proportion was 1:1 during most of the study period; however, females outnumbered males in January and September. Males reached a larger maximum size than females (27.1 and 24.0 mm CL, respectively). The presence of juveniles was restricted principally to the time between February and May. Sexual maturity was reached at a size of 20.8 mm (males) and 18.1 mm CL (females). The main breeding period lasted from autumn to winter (May to August, peaking in June), and co-occurred with decreasing water temperatures and the presence of a sediment layer covering the burrows.

Crustacean fauna (Stomatopoda: Decapoda) associated with the deepwater fishery of Heterocarpus vicarius (Decapoda: Pandalidae) along the Pacific coast of Costa Rica

Commercial bottom trawlng is a successful and commonly used method to catch marine shrimps. However, the shrimp fishing gears are poorly selective, and in addition to the target species they catch and retain large quantities of non-target species (bycatch). This study presents data concerning species composition and depth distribution of the crustacean fauna (stomatopods and decapods) associated with Heterocarpus vicarius catches from Pacific Costa Rica. A total of 74 samples (three to five 20 min-tows each month) were taken between January 2004 and December 2005 with commercial shrimp trawlers at depths varying between 192 and 350 m. In all depth ranges analyzed, total catch of crustaceans was significantly higher than that of fishes. A total of 28 decapods and two stomatopod species were identified. In comparison to other bycatch composition of comparable fisheries in Latin America, the crustacean fauna of the H. vicarius fishery in Costa Rica is highly diverse. Most common species were Solenocera agassizii (Solenoceridae), Squilla biformis (Squillidae), Plesionika trispinus (Pandalidae), and Pleuroncodes sp. (Galatheidae), reaching total catch percentages of 57.2 %, 81.5 %, 91.8 %, and 99.6 % of individual catches, respectively. The results presented herein may contribute to the development of responsible management strategies for the deepwater fisheries in Costa Rica and Central America.

Las redes de arrastre son un método exitoso y comúnmente utilizado para la pesca de camarones marinos. Sin embargo, son poco selectivas y, junto con las especies comerciales, se pesca también grandes cantidades de otras especies (fauna acompañante). Este estudio presenta información acerca de la composición y distribución batimétrica de los crustáceos (estomatópodos y decápodos) asociados con las capturas de Heterocarpus vicarius en el Pacífico de Costa Rica. Entre enero del 2004 y diciembre de 2005, se tomaron 74 muestras en profundidades de 192-350 m (tres a cinco arrastres de 20 min cada mes), utilizando redes de arrastre comercial dirigidas a la pesca de camarones. En todos los intervalos de profundidad analizados, las capturas (kg) de crustáceos fueron significativamente mayores que las de los peces. Se identificaron 28 especies de decápodos y dos de estomatópodos. Al comparar la composición de especies de fauna acompañante de H. vicarius en Costa Rica con otras pesquerías de camarones en América Latina, se encuentra que la fauna de crustáceos es muy diversa. Las especies más comunes fueron Solenocera agassizii (Solenoceridae), Squilla biformis (Squillidae), Plesionika trispinus (Pandalidae) y Pleuroncodes sp. (Galatheidae),alcanzando porcentajes máximos de concentración - en un sólo arrastre - de hasta 57.2 %, 81.5 %, 91.8 % y 99.6 % de la captura, respectivamente. Los resultados presentados aquí pueden contribuir al desarrollo de estrategias de manejo responsable para las pesquerías de aguas profundas en Costa Rica y en Centroamérica.