Characterization of oxidative stress biomarkers in a freshwater anomuran crab / Caracterização de biomarcadores de estresse oxidativo em caranguejos anomuros de água doce

Abstract In general, environmental responses at level of populations or communities are preceded by alterations at lower biological levels which can be efficiently detected by the analysis of biomarkers. We analyzed the oxidative biomarkers TBARS and Catalase in Aegla singularis, a freshwater crustacean highly sensitive to environmental changes. The objective was to address if are differences in these biomarkers related to the gender as well if they are influenced by seasonal or water physicochemical variables. The results showed differences in biomarkers profile related to the gender. In female crabs were not sensitive to seasonal variations throughout the study period. However, in males the biomarkers evaluated were higher in the winter as compared to remaining seasons and showed tendency of negative correlation with water temperature and pH. This study highlights that gender, seasonal variations and physicochemical variables can influence oxidative stress biomarkers in A. singularis. Female crabs probably are better suited as a model for biomarker application in environmental studies, because their insensibility to seasonal variations can facilitate the observations of responses related specifically to environmental disturbances.

Resumo Em geral, as respostas ambientais ao nível de populações ou comunidades são precedidas pelas alterações nos níveis biológicos inferiores que podem ser eficientemente detectados pela análise de biomarcadores. Neste trabalho, foram analisados os biomarcadores oxidativos TBARS e Catalase em Aegla singularis, um crustáceo de água doce altamente sensível às mudanças ambientais. O objetivo foi investigar se há diferenças nestes biomarcadores relacionados com o gênero, bem como se eles são influenciados por parâmetros sazonais ou físico-químicos. Os resultados mostraram diferenças no perfil de biomarcadores relacionados com o gênero. Caranguejos fêmeas não foram sensíveis a variações sazonais ao longo do período de estudo. Nos machos, os biomarcadores avaliadas apresentaram níveis mais altos no inverno, em comparação com as demais estações e mostraram uma tendência de correlação negativa com a temperatura e pH da água. Este estudo destaca que o sexo, variações sazonais e variáveis físico-químicas podem influenciar os biomarcadores de estresse oxidativo em A. singularis. As fêmeas de A. singularis provavelmente são mais adequadas como um modelo para aplicação destes biomarcadores em estudos ambientais, uma vez que sua insensibilidade às variações sazonais podem facilitar as observações das respostas relacionadas especificamente com perturbações ambientais.

Reproductive biology of Sodhiana iranica (Brachyura: Gecarcinucidae) from Southern Iran / Biología reproductiva del cangrejo de agua dulce Sodhiana iranica (Brachyura: Gecarcinidae) del sur de Irán

Abstract:Freshwater crab, Sodhiana iranica, is an endemic gecarcinucid crab that has been recently reported from Southern Iran. This research examined some reproductive aspects of S. iranica from Eelood freshwater spring, Southern Iran. Crabs were haphazardly sampled from April 2012 to April 2013, on a bimonthly basis. Measurements of Gonado-Somatic Index (GSI), Hepato-Somatic Index (HSI), oocyte diameter, and other aspects such as carapace width (CW) and total body weight (TW) were made in the captured specimens. Results showed a single seasonal reproductive cycle. Maturation and spawning occurred from December 2012 to April 2013 during the study period. The peaks of HSI were observed in April 2012 and February 2013. The oocyte diameter showed its most significant increase between August 2012 and February 2013. Considering the single seasonal breeding of S. iranica, a correct management, during the reproductive cycle, is necessary to support a healthy stock of this crab. Rev. Biol. Trop. 65 (1): 365-373. Epub 2017 March 01.

ResumenEl cangrejo agua dulce Sodhiana iranica es un cangrejo gecarcinucido que ha sido recientemente encontrado en el sur de Irán. Este trabajo examina algunos aspectos de la reproducción del cangrejo de agua dulce S. Iranica en el manantial Eelood del sur de Irán. Los cangrejos se muestrearon al azar entre abril 2012 y abril 2013 cada dos meses. Las mediciones del índice gonadosomático, el hepatosomático (HSI), el diámetro de los ovocitos y las observaciones de las etapas de maduración de los especímenes capturados, revelaron un único ciclo reproductivo estacional. La maduración y el desove se produjeron entre Diciembre 2012 y Abril 2013. El pico del índice hepatosomático se observó en Abril 2012 y Febrero 2013, respectivamente, y resultó más significativo el incremento en la media del diámetro de los ovocitos, que se produjo entre Agosto 2012 y Febrero 2013. En este estudio, se encontró que S. iranica se reproduce una vez al año estacionalmente. Por lo anterior, la gestión correcta durante el ciclo reproductivo de esta especie es necesaria para mantener la naturaleza y salud del stock de cangrejo.

Efectos del disturbio humano sobre la dinámica poblacional de Ocypode quadrata (Decapoda: Ocypodidae) en playas del Caribe mexicano / Effects of human disturbance on the population dynamics of Ocypode quadrata (Decapoda: Ocypodidae) in beaches of the Mexican Caribbean

Resumen:El cangrejo fantasma Ocypode quadrata, tiene una alta relevancia ecológica en las playas del Atlántico occidental y se ha propuesto como un indicador del impacto humano sobre este ecosistema. Sin embargo, no se han evaluado los efectos del disturbio humano sobre su dinámica poblacional. En este trabajo se compara la abundancia, el crecimiento y la mortalidad de O. quadrata en dos playas perturbadas (Aventuras y Majahual) y dos playas conservadas (Xcacel y Puerto Ángel) de las costas del Caribe mexicano. Se realizaron nueve muestreos en cada playa (marzo/2013-noviembre/2014). Durante las primeras horas de la noche se recolectaron cangrejos, de forma manual por tres personas, en un área aproximada de 9 000 m2. Los cangrejos fueron medidos, pesados y separados en tres grupos: jóvenes, hembras y machos. La mayor abundancia de cangrejos se encontró en las playas conservadas pero solo se observaron diferencias significativas entre Puerto Ángel y Majahual (Tukey, p<0.05). La proporción jóvenes- adultos fue 1:1 en Xcacel y Aventuras. En Majahual se recolectó un mayor número de jóvenes que adultos y en Puerto Ángel el número de adultos triplicó el de jóvenes. La talla máxima para Aventuras, Xcacel, Majahual y Puerto Ángel fue de 27, 32, 25 y 30 mm, respectivamente. En las playas se encontraron entre dos y tres grupos de edades diferentes. En las cuatro playas se recolectaron individuos con tallas menores de 10 mm en casi todos los meses de muestreo, indicando que el reclutamiento es continuo durante todo el año. La relación entre la longitud y el peso del cangrejo fantasma fue isométrica en las playas mejor conservadas y alométrica negativa en las playas impactadas. Los cangrejos de Puerto Ángel mostraron mejor condición corporal que en el resto de las playas (Tukey, p<0.05). Los valores de K oscilaron entre 0.6-0.97/año y la L∞ entre 29.0-33.6 mm. Los cangrejos en las dos playas conservadas mostraron mayores parámetros de crecimiento en comparación con las dos playas perturbadas. Los mayores valores de mortalidad se encontraron en Xcacel y Aventuras. En las playas perturbadas, la destrucción de las dunas, la limpieza mecánica y la remoción de materia orgánica, parecen ser las principales causas que conllevan a una baja abundancia de cangrejos, un menor crecimiento y una alta mortalidad. Sin embargo en las playas mejor conservadas, las relaciones biológicas parecen ser más importantes en regular la dinámica poblacional de esta especie. Estos resultados tienen relevancia desde el punto de vista de manejo de las playas arenosas, ya que el cangrejo fantasma es un buen indicador del disturbio humano y sus respuestas poblacionales son medibles y comparables.

Abstract:The ghost crab Ocypode quadrata is a relevant species in the Western Atlantic beaches, and has been proposed as an indicator of human impact in these ecosystems. Eventhough some studies have covered various aspects of its natural history, no evaluations on the effects of human disturbance on its population dynamics have been made. This work compared the abundance, growth, and mortality of O. quadrata in two disturbed beaches (Aventuras and Majahual) and two preserved beaches (Xcacel and Puerto Angel) from the Mexican Caribbean. For this, nine samplings were made on each beach (every two to three months) between March 2013 and November 2014. Crabs were collected manually by three people, during the night first hours and for one hour, and a total area of 9 000 m2 per beach. The crabs were measured, weighed, and separated into three groups: juvenile, male and female; while abundance was estimated by the number of collected crabs, and growth parameters were estimated using length frequencies. A total of 1 047 crabs were sampled in the four beaches; a higher crab abundance was found in the preserved beaches, but significant differences were only found between Puerto Angel and Majahual (Tukey, p<0.05). The adult- juvenile ratio was 1:1 in Xcacel and Aventuras, while in Majahual, more juveniles than adults were collected; and Puerto Angel had more adults than the juveniles. The size structure at Xcacel ranged from 4-32 mm, but in the rest of the beaches the minimum size was 5 mm. The maximum size at Aventuras, Majahual and Puerto Angel were 27 mm, 25 mm and 30 mm, respectively. The modal progression analysis of length's pooled data, revealed the presence of at least two groups of ages in all beaches. For all beaches, individuals smaller than 10 mm length were collected in almost all sampling months, indicating a continuous recruitment throughout the year. The length-weight relationship of the ghost crab was found isometric in the two preserved beaches, and negative allometric at the two impacted beaches. Crabs from Puerto Angel showed the highest body condition (Tukey, p<0.05). K-values ranged from 0.6-0.97/year and L∞ from 29.0 mm to 33.6 mm with higher values for the two preserved beaches. The highest mortality values were found in Xcacel and Aventuras. In the disturbed beaches, the destruction of the dunes, the mechanical cleaning and the removal of organic matter, seem to be the main causes that lead to a low abundance of crabs, their slower growth and higher mortalities. However, in the best preserved beaches, biological interactions appear to be the most important aspects in regulating the population dynamics of this species. These results supported the information that the ghost crab is a good indicator of human disturbance, and its population changes were clearly measurable and comparable among protected and impacted beaches; these results are also relevant for the management of sandy beaches in the Mexican Caribbean. Rev. Biol. Trop. 64 (4): 1625-1641. Epub 2016 December 01.

Reproductive features of the swimming crab Callinectes danae(Crustacea, Portunoidea) on the subtropical coast of Brazil: a sampling outside the estuary / Características reprodutivas do siri Callinectes danae(Crustacea, Portunoidea) na região subtropical da costa do Brasil: uma amostragem fora do estuário

AbstractThe life cycle of the crab Callinectes danae is estuarine-dependent, and studies on aspects of their biology should also cover marine areas. The present study investigated the sexual maturity, as well as habitat preference by adults in different gonadal stages, and the crabs’ reproductive periodicity outside the estuary. Three bays on the subtropical southeastern coast of Brazil were sampled monthly for two years. For each bay, six transects were established, four of them parallel to the beach line (5, 10, 15 and 20 m depth), as well as one transect in an exposed area, and another sheltered from the action of waves. The results showed that the pattern of spatio-temporal distribution of adults C. danae was similar in three bays, although the highest abundance was found in Ubatumirim. Females with developed gonads/ovigerous females were found in greater abundance than females with rudimentary/developing gonads, mainly in deeper transects. Although the areas sampled have different environmental characteristics, the reproductive pattern of the species did not change, showing continuous reproduction throughout, with more abundance of reproductive females on spring and summer. Males reached maturity at larger sizes than females in all three bays.

ResumoO siri Callinectes danae é estuarino dependente em seu ciclo de vida, sendo que os estudos que levantam informações sobre os aspectos da sua biologia devem também abranger regiões marinhas. Assim, o presente estudo teve como objetivo investigar a maturidade sexual, bem como a preferência ocupacional por adultos em diferentes estágios gonadais e sua periodicidade reprodutiva fora da região estuarina. Para tanto, três enseadas da porção subtropical do litoral sudeste brasileiro foram amostradas mensalmente, durante dois anos. Para cada enseada, seis transectos foram estabelecidos, quatro deles paralelos à linha de praia (5, 10, 15 e 20m de profundidade), um transecto exposto e outro abrigado à ação de ondas. Os resultados mostraram que o padrão de distribuição espaço-temporal de adultos de C. danae foi similar nas três enseadas, embora uma maior abundância tenha sido encontrada em Ubatumirim. Fêmeas ovígeras e com gônadas desenvolvidas foram encontradas em maior abundância que fêmeas com gônadas rudimentares e em desenvolvimento, principalmente nos transectos mais profundos. Apesar das regiões amostradas possuírem características ambientais diferenciadas, o padrão reprodutivo da espécie não sofreu alterações, apresentando reprodução contínua, com maior abundância de fêmeas reprodutivas na primavera e verão. Machos atingiram maturidade em tamanhos maiores que as fêmeas nas três enseadas.

Differential habitat use by demographic groups of the redfinger rubble crab Eriphia gonagra (Fabricius, 1781) / Ocupação diferencial do habitat por grupos demográficos do caranguejo de dedos vermelhos Eriphia gonagra (Fabricius, 1781)

The structurally diverse rocky shores along the northern coast of the state of São Paulo, Brazil, support a varied fauna and provide refuges for many organisms. Some of these environments allow for extensive microhabitats, among them the sand reefs formed by the polychaete Phragmatopoma lapidosa, which occupy much of this area. The beauty of the landscape attracts large numbers of tourists, who contribute to the damage to the sand reef colonies, causing an imbalance in the patterns of population distribution and of this ecosystem. We describe the structure and population biology of the redfinger rubble crab Eriphia gonagra, and investigated the differential occupation of the habitat by each demographic category of this species. Crabs were sampled monthly for two consecutive years on the rocky coast of Grande Beach, Ubatuba, São Paulo, during spring low tides. Sampling was carried out over an area of approximately 1200 m2, during two hours on the rock surface and another two hours on the sand reefs. A total of 1407 crabs were collected; 776 on the sand reef (SR) and 631 on the rocky shore (RO). The majority of juvenile crabs inhabited the SR, while adult crabs were equally distributed in both microhabitats. This study showed that the SR is a natural nursery ground for the establishment of the early juvenile stages of E. gonagra, which use the reefs as a refuge and food resource. Many other organisms (mollusks, echinoderms, polychaetes etc.) settle on the reefs, and these areas may be among the most important in maintaining benthic diversity in the region.

Os costões rochosos do litoral norte paulista, devido à sua constituição diversificada, sustentam uma grande diversidade de espécies animais e vegetais, além de proporcionar uma série de abrigos para proteção de muitos organismos. Em alguns destes costões ocorre a formação de microhabitats, entre eles os recifes de areia formadas pelo poliqueta Phragmatopoma lapidosa, que ocupam grande parte desta área. A paisagem diferenciada do local atrai um grande número de turistas, o que contribui para a deterioração das colônias que constituem esse recife, causando um desequilíbrio nos padrões de distribuição das populações desse ecossistema. Este trabalho visou levantar informações sobre a estrutura e dinâmica populacional de Eriphia gonagra, além de investigar uma ocupação diferencial do habitat por diferentes grupos etários deste caranguejo. Os caranguejos foram amostrados mensalmente, durante dois anos consecutivos, no costão rochoso da Praia Grande, Ubatuba, São Paulo, Brasil, em períodos de marés baixas de sizígia. A coleta ativa dos indivíduos foi efetuada em uma área de aproximadamente 1200 m2 por um período de duas horas na superfície rochosa e outras duas horas nos recifes de areia. Foi capturado um total de 1407 indivíduos, sendo 776 no recife de areia (SR) e 631 na superfície rochosa (RO). A maior parte dos jovens habita o recife, enquanto adultos encontram-se igualmente distribuídos nas duas áreas amostradas. Este estudo mostra que os recifes de areia podem ser considerados berçários de suma importância para o estabelecimento dos estágios juvenis de E. gonagra, que utilizam tais locais para proteção e alimentação. Muitos outros organismos (moluscos, equinodermos, poliquetas etc) se estabelecem sobre os recifes, sendo que essas áreas podem estar entre as mais importantes na manutenção da diversidade bêntica na região.

Chemical defense in the red seaweed Plocamium brasiliense: spatial variability and differential action on herbivores / Defesa química na macroalga marinha vermelha Plocamium brasiliense: variabilidade espacial e diferentes ações sobre herbívoros

Species of Plocamium are known as prolific sources of halogenated secondary metabolites exhibiting few explored ecological roles. In this study the crude extracts from specimens of P. brasiliense collected in two distinct places, Enseada do Forno and Praia Rasa, Búzios, Estado do Rio de Janeiro, were evaluated as defense against the sea urchin Lytechinus variegatus and the crab Acanthonyx scutiformis. These specimens produce a similar amount of crude extract and also halogenated monoterpene compound-types, but individuals of P. brasiliense from Praia Rasa exhibit a major compound representing about 59% of the total chemicals. Natural concentrations of the crude extracts obtained from both specimens of P. brasiliense significantly inhibited the herbivory by the sea urchin L. variegatus, but had no significant effect on the feeding by A. scutiformis, a crab commonly associated to chemically defended host. Crude extract from P. brasiliense collected at Praia Rasa was more efficient as defense against L. variegatus than that crude extract from populations of this alga from Enseada do Forno, probably due to presence of a major secondary metabolite. These two studied population live under different environmental conditions, but they are only about 30 Km apart. However, it is impossible to affirm that environmental characteristics (abiotic or biotic) would be responsible for the difference of defensive potential found in the two populations of P. brasiliense studied here. Further genetic studies will be necessary to clarify this question and to explain why populations of a single species living in different but close locations can exhibit distinct chemicals.

Espécies de Plocamium são conhecidas como fontes prolíficas de metabólitos secundários halogenados com significados ecológicos pouco conhecidos. Neste trabalho extratos brutos de espécimes de P. brasiliense coletados em duas localidades distintas, Enseada do Forno e Praia Rasa, Búzios, Estado do Rio de Janeiro, foram avaliados como defesa química contra o ouriço Lytechinus variegatus e o caranguejo Acanthonyx scutiformis. Estes espécimes produzem teores similares de extrato bruto e tipos de substâncias monoterpenos halogenados, mas os indivíduos da Praia Rasa possui um componente majoritário representando 59% do total de metabólitos. Concentrações naturais dos extratos brutos destes espécimes inibiram significativamente o consumo por L. variegatus, mas não causaram qualquer efeito sobre A. scutiformis, um caranguejo comumente associado a P. brasiliense, um hospedeiro quimicamente defendido. O extrato bruto de P. brasiliense coletada na Praia Rasa foi mais eficiente como defesa frente a L. variegatus do que aquele obtido de população desta alga da Enseada do Forno, provavelmente pela presença de uma substância majoritária. Estas duas populações de P. brasiliense estudadas vivem sob diferentes condições ambientais, mas distantes somente cerca de 30 km. Entretanto, é impossível afirmar que características ambientais (abióticas ou bióticas) seriam responsáveis pelas diferenças de potencial defensivo encontrados nestas duas populações de P. brasiliense estudadas. Futuros estudos genéticos são necessários para esclarecer esta questão e para explicar porque populações de uma mesma espécie vivendo em regiões tão próximas, mas ambientalmente distintas, produzem substâncias distintas.

Fecundity, reproductive seasonality and maturation size of Callinectes sapidus females (Decapoda: Portunidae) in the Southeast coast of Brazil

C. sapidus fisheries has a significant influence on the economy of some countries in North America and has a relative extensive literature in these regions. However, only few papers discuss the ecology of C. sapidus in the South Atlantic, despite its economic importance in that region. We studied the fecundity, reproductive seasonality and maturation size of C. sapidus females captured in the Southeast coast of Brazil from January to December 2002. Females were separated, weighted (Wt), and cephalothorax width (CW) was measured. Furthermore, the eggs-masses were classified according to embryonic development, separated, weighted (We) and fixed. Eggs were also separated and counted, resulting in the average number of eggs per individual (Ne). A total sample of 307 females was collected: 78 young, 130 adults and 99 ovigerous. Ovigerous females showed CW between 7.49 and 15.89cm with average of 12.21cm and were distributed throughout the sample period, with highest incidence between December and March. The onset of morphological maturity (L50) occurred at CW=10.33cm, and the size in which all were mature (L100) was CW=11.20cm. Individual fecundity ranged from 689 356 to 3 438 122 with an average of 2 006 974. The CW showed a positive growth trend with Ne and We. We concluded that in order to ensure the resource sustainability, it is necessary to prohibit captures of C. sapidus in these regions, especially during summer. Additionally, our studies suggest that the minimum capture size should be 11cm of carapace width.

Hay pocos estudios sobre la ecología de C. sapidus en el Atlántico Sur, a pesar de su importancia económica en la región. El presente estudio tiene como objetivo conocer la fecundidad, periodo reproductivo y talla de primera madurez morfológica de las hembras de C. sapidus, con el fin de contribuir a una mejor comprensión de la especie en el Atlántico occidental, así como ayudar en la toma de medidas de gestión en la región. Las muestras fueron recolectadas mensualmente de enero a diciembre 2002 en sudeste del Brazil. Se recogieron 307 hembras: 78 jóvenes, 130 adultos y 99 ovígeras. Las hembras ovígeras mostró su intervalo de talla de 7.49-15.89cm ancho del carapazón (AC) y se distribuyeron en todo el período de la muestra, con mayor incidencia entre diciembre y marzo. El inicio de la madurez morfológica (L50) fue con la AC=10.33cm y el tamaño que tenían todos los maduros (L100) con AC de 11.20cm. Fecundidad individual osciló entre 689 356 a 3 438 122, con una media 2 006 974. El AC mostró una tendencia positiva en el crecimiento con número de huevos y el peso del huevos. El conocimiento de los aspectos reproductivos de la población es importante en la definición de medidas de gestión para el uso sostenible con el fin de renovar y continuar con la misma.

Breeding period in the mangrove crab Goniopsis cruentata (Decapoda: Grapsidae) in Northeast Brazil

The brachyuran crabs are iteroparous species which present a high diversification of reproduction patterns, which may have evolved as a species-specific response to environmental conditions. Tropical species commonly present a year-round reproduction due to stable environment conditions. Goniopsis cruentata is a crab species widely distributed along the Western Atlantic, inhabiting practically every microhabitat in the mangrove ecosystem. The aim of the present study is to determine the breeding period of the crab Goniopsis cruentata in Northeastern Brazil and also to evaluate the influence of water salinity, rainfall and air and water temperature on it. A total of 71 ovigerous females, captured from August-2007 to July-2008, were used to assess the breeding period of this species. It was analyzed by the monthly proportion of ovigerous females. A correlation was applied to verify the influence of the abiotic factors on the breeding period. The present population bred seasonal-continuously with peaks in the dry period, which was not associated with monthly variations of salinity, rainfall and air and water temperatures. Therefore, according to statistical analyses, our hypothesis was refuted. However, breeding was intensified in the dry period, when salinity and temperatures were higher and rainfall was lower. We conclude that, even though breeding is not related to monthly variation of environmental factors, it occurs in periods of higher salinity and temperatures and lower rainfall.

Los cangrejos Brachyura son especies iteróparas, que presentan alta diversificación en los patrones de reproducción, que pueden haber evolucionado como una respuesta específica de la especie a las condiciones ambientales. Las especies tropicales frecuentemente presentan una reproducción en todo el año debido a las condiciones estables del medio. El cangrejo Goniopsis cruentata es una especie ampliamente distribuida en largo del Atlántico occidental, y que habita prácticamente cada micro-hábitat en el ecosistema de manglar. El objetivo del presente estudio fue evaluar el periodo de reproducción del cangrejo G. cruentata en el noreste de Brasil. Un total de 71 hembras ovadas, fueron capturadas entre agosto 2007 y julio 2008, y utilizadas para obtener el periodo de reproducción de esta especie. Nuestra hipótesis es que, ya que las zonas tropicales no presentan gran variación de las temperaturas, las oscilaciones temporales de la salinidad son el principal factor que influye en la actividad reproductiva de G. cruentata. Se analizó el período reproductivo mediante la proporción mensual de hembras ovadas. Una correlación fue aplicada para evaluar la influencia de los factores abióticos limitantes (salinidad, pluviosidad, temperatura del aire y del agua) en la época de crianza. La población se reproduce continuamente con picos estacionales en el período seco, lo que no fue asociado a las variaciones mensuales de salinidad, precipitación y temperatura del aire y del agua. Por lo tanto, nuestra hipótesis fue refutada. Sin embargo, la reproducción se intensificó en el período seco, cuando la salinidad y las temperaturas fueron más altas y la precipitación fue menor. Se concluye que, a pesar de que la reproducción no está relacionada con la variación mensual de los factores ambientales limitantes, ella ocurre en períodos de mayor salinidad y temperatura, y baja precipitación.

Influence of natural settlement cues on the metamorphosis of fiddler crab megalopae, Uca vocator (Decapoda: Ocypodidae)

Megalopae of many decapod crab species accelerate their development time to metamorphosis (TTM) when exposed to natural physical and/or chemical cues characteristic of the parental habitat. In the present study, the influence of natural settlement cues on the moulting rates and development TTM in megalopae of the fiddler crab Uca vocator was investigated. The effects of mud from different habitats (including well-preserved and degraded-polluted mangrove habitats) and conspecific adult 'odours' (seawater conditioned with crabs) on the induction of metamorphosis were compared with filtered pure seawater (control). 95 to 100 percent of the megalopae successfully metamorphosed to first juvenile crab stage in all treatments, including the control. However, the development TTM differed significantly among treatments. Settlement cues significantly shortened development, while moulting was delayed in their absence. The fact that megalopae responded to metamorphosis-stimulating cues originating from both adult and non-adult benthic habitats demonstrates that settlement in this species may occur in a wider range of habitats within the mangrove ecosystem, including impacted areas.

Megalopas de muitas espécies de caranguejos decápodes aceleram seu período de desenvolvimento até a metamorfose (TOM) quando são expostas a estímulos naturais físicos e/ou químicos característicos do habitat parental. No presente estudo, a influência de estímulos naturais sobre as taxas de muda e sobre o PDM foi investigada nas megalopas do caranguejo violinista Uca vocator. Os efeitos da (i) lama de diferentes habitats (incluindo habitats de um manguezal bem preservado e de um degradado e poluído) e (ii) 'odores' dos adultos conspecíficos (água do mar acondicionada com caranguejos) sobre a indução da metamorfose foram comparados com (iii) água do mar pura e filtrada (controle). 95 a 100 por cento das megalopas realizaram a metamorfose com sucesso para o primeiro estágio de caranguejo juvenil em todos os tratamentos, incluindo o controle. No entanto, o PDM diferiu significativamente entre os tratamentos. Os estímulos encurtaram significativamente o desenvolvimento, enquanto que a muda foi retardada na ausência deles. O fato de que as megalopas responderam aos estímulos indutores da metamorfose oriundos de ambos os habitats bentônicos dos adultos e de habitats onde eles são ausentes, demonstra que o assentamento nesta espécie pode ocorrer em uma grande variedade de habitats dentro do ecossistema de manguezal, incluindo áreas impactadas.

Biodiversidad, morfometría y alimentación de los cangrejos del género Callinectes (Decapoda: Portunidae) en Santiago de Cuba

Biodiversity, morphometry and diet of Callinectes crabs (Decapoda: Portunidae) in Santiago de Cuba. On the basis of fishery intensity and proximity to river mouth, a total of 257 swimming Callinectes crabs were collected from March 2007 to April 2008 in eight localities. Captures were made with hanging nets, to a maximal depth of 1.5m, establishing a top time of 2 hr. The genus was widely distributed, and it is represented at least by four species: C. sapidus, C. similis, C. rathbunae and C. larvatus, the last two not included in the last list of Cuban crustaceans (Crustacea: Decapoda). The size and shape of the gonopods were very useful as taxonomical criteria, considering the prevalence of males. The most abundant species were C. sapidus (47.08%), and C. similis (30.35%). C. rathbunae, which was identified at 75% (6) of the localities, showed a better distribution, followed by C. sapidus, which appears in the 63% (5). Sex rate (Rs) by species (male:female) was 6.20 for C. rathbunae, 3.58 for C. similis, 1.40 for C. larvatus and 0.40 for C. sapidus. The most abundant species had a lower Rs value. Morphometrical analysis and weight allowed us to know the average carapace width (CW) and weight (W). C. sapidus had an average CW = 110.57 mm (DS 21.55, n = 121) and W = 84.46 g (SD 43.25, n = 121); C. rathbunae a CW = 115.50 mm (DS 14.94, n = 36) and W = 140.44 g (DS 55.02, n = 36); C. larvatus a CW = 76.04 mm (DS 10.88, n = 22) and W = 31.70 g (DS 14.67, n = 22); and C. similis had the minimal parameter values, with a CW = 59.77 mm (DS 14.09, n = 78) and W = 13.80g (DS 10.00, n = 78). These are the first records of the coastal crabs in the area. All values are lower than in previous reports. The largest individuals (CW>140 mm: C. rathbunae and C. sapidus) were captured in localities with adequate environmental characteristics. The stomach content suggests nine dietary categories, mainly fishes and macroalgae. The genus Callinectes has a diversified trophic spectrum. These crabs eat the available food, but they have a preference for the most abundant items. Rev. Biol. Trop. 57 (3): 671-686. Epub 2009 September 30.

El objetivo del presente trabajo es el estudio del género Callinectes en la zona costera del municipio de Santiago de Cuba. Se realizó una recolecta de 257 ejemplares durante marzo de 2007 a abril de 2008, en ocho estaciones a lo largo de la costa. El género resultó estar ampliamente distribuido en el litoral y representado al menos por cuatro especies: C. sapidus, C. similis, C. rathbunae y C. larvatus, las dos últimas no incluidas en la lista publicada de crustáceos (Crustacea: Decapoda) cubanos. Las especies más abundantes resultaron ser C. sapidus y C. similis. C. rathbunae fue la más ampliamente distribuida. El análisis del contenido estomacal permitió identificar nueve categorías alimentarias, siendo las más importantes los peces y las macroalgas. Las especies de Callinectes tienen un amplio espectro trófico; comen no sólo lo disponible, sino también lo más abundante.

Observaciones sobre la larva del cangrejo marino tropical (Decapoda: Porcellanidae) Petrolisthes armatus en el Golfo de Nicoya, Costa Rica

Observations on the larvae of the tropical marine crab Petrolisthes armatus in the Gulf of Nicoya, Costa Rica. During October and November 1998 (rainy season), and December, February and March 1999 (dry season), larvae distribution of Petrolisthes armatus and associated decapods were sampled in three different sites at the Punta Morales peninsula, Gulf of Nicoya, Costa Rica. A total of 6014 decapod larvae were collected, and 73 belonged to the genus Petrolisthes spp. No significant total larval density differences were found between seasons (p>0.05); but there was a greater density of P. armatus and other decapod larvae (p>0.05) during the dry season. In addition, no significant variations on temperature and oxygen concentration were observed. P. armatus larval abundance was higher during low tide, in contrast with other decapod larvae. Significant differences among sites were found for other decapod larvae, but not for P. armatus. The only parameter that varied significantly between seasons was salinity and results demonstrate that this factor regulates temporal concentration of larvae. Moreover, flow-tide oscillations were the most important spatial factor in larval dynamics. We propose this mechanism: P. armatus liberates larvae during high tide; these larvae leave the coastal area during low tide and return to the rocky intertidal ecosystem during high tide, when they are ready to settle as megalopa (pre-juvenile stage). Parallel laboratory observations showed higher survival rates at lower salinities (15 ups against 35 ups) and that the duration of the period from zoea I to megalopa was, in average, 19 days. Rev. Biol. Trop. 56 (3): 1209-1223. Epub 2008 September 30.

Durante octubre y noviembre de 1998 (estación lluviosa) y diciembre, febrero y marzo de 1999 (estación seca) se muestreó la distribución de la larva de Petrolisthes spp, así como la densidad del total de las larvas de decápodos en superficie y a 3 metros de profundidad. Los muestreos se realizaron en tres sitios de la zona de Punta Morales, Golfo de Nicoya, Costa Rica, por medio de arrastres con una red de plancton de 280 µm. Se recolectaron un total de 6014 larvas de decápodos de las cuales 73 (1.21%) pertenecían al género Petrolisthes spp. No se encontraron diferencias significativas entre estaciones (p > 0.05), sin embargo fue posible observar una mayor densidad tanto de P. armatus como de larvas de decápodos en estación seca. Temporalmente el único parámetro físico-químico que varió significativamente fue la salinidad. En cuanto a la variación espacial no se encontraron diferencias significativas por profundidad, ni para Petrolisthes spp. ni para larvas de decápodos asociados (p > 0.05), a pesar de que la variación de algunos parámetros como la temperatura y el oxígeno si lo fue. Entre mareas se encontraron diferencias significativas para las larvas de Petrolisthes spp., no así para larvas de decápodos. Para la especie estudiada se observó un mayor número de larvas en marea baja. Entre los sitios hubo diferencias significativas para las larvas de decápodos, pero no para Petrolisthes spp.; físico-químicamente estos sitios son muy parecidos y solo difieren en penetración de luz, lo que parece no afectar a la larva de Petrolisthes. spp. Los resultados demuestran que el principal factor que regula la concentración temporal de las larvas es la salinidad, mientras que espacialmente las oscilaciones en el flujo mareal son de mayor importancia. Debido a las diferencias observadas marealmente para la concentración de larvas se propone el siguiente mecanismo: P. armatus libera sus larvas en el máximo de marea, éstas salen hacia fuera de la costa con la marea baja y se reincorporan con la marea alta, cuando están cerca de la fase previa al asentamiento (la megalopa). Adicional a los resultados en el medio natural para esta especie también se estudió en el laboratorio la duración del periodo larval y la supervivencia de las larvas a salinidades extremas utilizándose los valores máximos y mínimos registrados en el medio natural (15 ups y 35 ups). Este ensayo demostró que las larvas presentan un mayor porcentaje de supervivencia en salinidades menores (15 ups) y que la duración del período de desarrollo es de 19 dias.

Fecundity of Uca uruguayensis and Chasmagnathus granulatus (Decapoda, Brachyura) from the "Refugio de Vida Silvestre" Bahía Samborombón, Argentina

The aim of the present work conducted at the Refugio de Vida Silvestre Bahía Samborombón is to analyse the most relevant aspects of the fecundity of Chasmagnathus granulatus and Uca uruguayensis. Samplings were carried out from March 2001 to February 2003. Ovigerous females of U. uruguayensis (N = 13) and C. granulatus (N = 25) were found during spring and summer, their sizes (CW) varied from 9.1 to 11.7 µm for the former species and from 22.8 to 32.4 mm for the latter. The egg diameter in U. uruguayensis ranged from 245 to 260 µm for embryos in the early stage of development and from 250 to 345 µm for those in mid-developmental stage, while in C. granulatus from 250t o 345 µm and from 260 to 365 µm respectively. Fecundity varied from 1126 to 6745 eggs/brood in U. uruguayensis and 15688-57418 eggs/brood in C. granulatus. For those females with broods in mid-developmental stage, several relationships were made. For U. uruguayensis the best correlation coefficients were obtained for the relationships: female weight vs. egg mass weight and carapace width vs. egg mass weight; for C. granulatus the best association was obtained between female size and the egg number and the egg mass weight.

O objetivo do presente trabalho foi analisar os aspectos mais relevantes da fecundidade de Chasmagnathus granulatus e Uca uruguayensis no Refúgio da Vida Silvestre Bahia Samborombón. As amostragens foram realizadas de março de 2001 a fevereiro de 2003. As fêmeas ovígeras de U. uruguayensis (N = 13) e de C. granulatus (N = 25) foram capturadas na primavera e verão. A largura da carapaça (LC) de U. uruguayensis variou de 9.1 a 11.7 mm, e de 22.8 a 32.4 mm para C. granulatus. O diâmetro dos ovos de U. uruguayensis variou de 245 a 260 µm para embriões em estágio de desenvolvimento inicial e de 250 a 345 mm para aqueles em estágio intermediário; para C. granulatus as variações foram de 250 a 345 µm e de 260 a 365 µm, respectivamente. A fecundidade de U. uruguayensis variou de 1126 a -6745 ovos/desova e para C. granulatus de 15688 a 57418 ovos/desova. Para as fêmeas com massa de ovos em estágio de desenvolvimento intermediário foram efetuadas várias relações: para U. uruguayensis os melhores coeficientes de correlação foram obtidos nas relações: peso da fêmea vs. peso da massa de ovos, e largura da carapaça vs. peso da massa de ovos. Para C. granulatus, a melhor associação foi obtida entre o número de ovos e o peso da massa de ovos.

Formación inicial de los espermatofóros en el testículo del cangrejo Uca uruguayensis (Brachyura: Ocypodidae) / Initial formation of spermatophores in the testicles of the crab Uca uruguayensis (Brachyura: Ocypodidae)

The functional anatomy of the male reproductive system of Uca uruguayensis from Mar Chiquita lagoon, (37º45' S, 57º26' W), Argentina, was known only from optical icroscopy. The present study describes the participation of vas deferens regions in spermatophore formation. A detailed description of the functional morphology of the different regions of the testicular lobes was carried out using both light and scanning electron microscopy. Spermatophore formation begins at the base of the testicular lobe. In most brachyuran species, the spermatophore starts formation when spermatozoa move from the collecting ducts of the testis to the vas deferens. However, in U. uruguayensis observations suggest that the formation of the spermatophore walls occurred in the terminal region of the testis, and that the spermatophore was formed at the junction of the testis and the vas deferens.

La anatomía funcional del sistema reproductor de los machos de Uca uruguayensis de la población de la laguna de Mar Chiquita (37º45' S, 57º26' W), Argentina, ha sido previamente estudiada empleando microscopía óptica. En el presente estudio se demostró la intervención del vaso deferente, en sus distintas regiones, en la formación del espermatóforo y la inclusión del fluido espermático. Se amplía la descripción de la morfología funcional de las regiones de los lóbulos testiculares (empleando también microscopía electrónica de barrido). La formación de los espermatóforos se inicia en la base del lóbulo testicular. El mecanismo descrito hasta el momento para la mayor parte de las especies de braquiuros postula que los espermatóforos comienzan a formarse cuando los espermatozoos pasan de los colectores del testículo al vaso deferente. Nuestras observaciones sugieren sin embargo, que en esta especie la formación de la pared del espermatóforo se inicia en la base de los lóbulos testiculares, y que los espermatóforos están completamente formados en la unión de los testículos y el vaso deferente anterior.

Molt and reproduction of the European green crab Carcinus maenas (Decapoda: Portunidae) in Patagonia, Argentina

The green crab Carcinus maenas, a decapod crustacean native to the northeastern Atlantic, has beeninvading distant areas, mainly for the last 25 years. This species is currently distributed along the coasts of thenortheastern Pacific, South Africa, Japan, South Australia, Tasmania, and western and eastern North America,among others. Here we provide information on the biology of the green crab occurring in the central area of SanJorge Gulf, Argentina, where it has been established since 1999-2000. Crabs of both sexes were hand-collectedbetween January 2004 and May 2005 from the intertidal zone and the upper sublittoral fringe. Sex, carapacewidth and molting stage were recorded. The reproductive status of males was based on the presence of sperm andspermatophores in testes and deferent ducts, and that of females on ovarian development and presence-absenceof eggs. Stages of embryonic development for ovigerous females were also recorded. The most importantphysiological events taking place during the annual cycle of the adult population were as follows: (1) male moltoccurred mainly in November and female molt between January and the beginning of March; (2) the reproductiveseason started in January, after a courtship in which the male, larger in size, holds the female until the molt,and spermatophores are ejaculated once the old exoskeleton is cast off; (3) females left the intertidal zone earlyand moved to lower littoral levels during fall and winter; (4) larvae appeared in September.

El cangrejo verde europeo es un crustáceo decápodo originario del Océano Atlántico nororiental, el cual principalmente en los últimos 25 años ha invadido, entre otros, el Pacífico nororiental, Sudáfrica, Japón, sur de Australia, Tasmania y ambas costas de América del Norte. Aquí resumimos las observaciones biológicas en el área central del Golfo San Jorge, Argentina, donde este cangrejo se ha instalado a partir de 1999 ó 2000. Recolectamos manualmente muestras de ambos sexos entre enero de 2004 y mayo de 2005 en el intermareal y la franja superior del sublitoral. La muda de los machos ocurre principalmente en noviembre y la de las hembras, entre enero y principios de marzo. La época reproductiva se inicia en enero, con un cortejo previo donde el macho, de mayor talla que la hembra, la retiene hasta la muda y, una vez desprendido el viejo exoesqueleto, se produce la eyaculación de los espermatóforos. Las hembras abandonan tempranamente el intermareal y migran a niveles inferiores del litoral durante el otoño e invierno, eclosionando las larvas en setiembre.

Population and reproductive biology of the crab Uca burgersi (Crustacea: Ocypodidae) in three subtropical mangrove forests

Population and reproductive biology were studied in three populations of the crab Uca burgersi Holthuis, 1967, in the Indaiá, Cavalo and Ubatumirim mangrove forests (Ubatuba, São Paulo State, Brazil). Crabs were collected during low tide (August 2001 through July 2002), by digging the sediment, with a standard capture effort (two persons for 30 min.). Carapace width was measured, and gonad developmental stage was recorded from all specimens. U. burgersi was most abundant in the Cavalo mangrove, where the largest male was found. Juvenile crabs were found year-round at all three sites. However, the ratio of ovigerous females was very low, even null in the Cavalo mangrove. The gonad development rate indicated that U. burgersi was reproducing continuously, but more intensively during spring and summer, with recruitment occurring in winter. The synchrony between the populational and reproductive biology in the three areas showed that local features were not the limiting factors. It is suggested that this species is a habitat generalist.

Estudiamos la biología poblacional y reproductiva de tres poblaciones de Uca burgersi Holthuis, 1967, en los manglares de Indaiá, Cavalo y Ubatumirim (Ubatuba, São Paulo, Brasil). Los cangrejos fueron recolectados por excavación de sedimentos, con un esfuerzo de capturaestándar (dos personas por 30 min), durante la marea baja, entre agosto 2001 y julio 2002. En todos los especimenes se midió la anchura del caparazón y se registró la etapade desarrollo gonadal. Esta especie fue más abundante en Cavalo, donde se halló el macho de mayor tamaño.Encontramos juveniles en los tres sitios, durante todo el período de estudio. Sin embargo, la proporción de hembrasovígeras fue muy baja (nula en Cavalo). Según el desarrollo gonadal, el periodo reproductivo fue continuo allí, pero más intenso durante la primavera y el verano, con reclutamiento en el invierno. La sincronía entre la biologíapoblacional y reproductiva de las tres poblaciones, demuestra que las características locales no fueron los factores limitantes. Se sugiere que esta especie es generalista con respecto al hábitat.

Secondary production of Chasmagnathus granulatus (Crustacea; Decapoda) in a Ramsar Site from Argentina

Secondary production of Chasmagnathus granulatus was calculated at the Refugio de Vida Silvestre Bahía Samborombón, Argentina (36° 16' S and 57° 06' W). Sampling was conducted on nine occasions between March 2001 and February 2003, crabs were collected by hand, physico-chemical variables, granulometry and organic matter contents of the sediments were registered. Crabs were classified as male, female and undifferentiated, measured (total carapace width: CW) and weighed (wet and dry weight: DW at 60 °C, during 48 hours). A correlation analysis between CW and DW was made. Morphometric growth of C. granulatus was by the application of the power function (y = a x b), where the carapace width (CW) was used as an independent variable. Males, females and undifferentiated individuals were analysed separately as well as all together as a group. The data were fitted indicating a positive allometry (constant of allometry b > 3), the males showing the greatest allometric value. The individuals (n = 957 juveniles and adults) were separated in cohorts by the polymodal width-frequency distribution converted into normal curves. Three cohorts were found during the whole study period, and two cohorts coexisting in each sampling date. Ovigerous females were caught on December 2001, 2002 and February 2003. The size-frequency method was used to estimate the annual production. The major contribution to production was carried out by the mature individuals, in particular those with size between 25 and 30 mm, but on the other hand, only few individuals measuring from 10 to 20 mm were collected. The annual production of C. granulatus was estimated in 7.76 g.m-2. The biomass (expressed as total dry weight) varied between 0.55 and 1.85 g.m-2, with the greater values being registered during autumn and spring, and the lower values during summer.

Foram calculadas as primeiras estimativas da produção secundária de Chasmagnathus granulatus no Refúgio da Vida Silvestre Bahía Samborombón, Argentina (36° 16' S e 57° 06' W). As amostragens foram realizadas em nove ocasiões, entre o período de março de 2001 a fevereiro de 2003. Os caranguejos foram coletados manualmente. Variáveis físico-químicas, granulometria e teor de matéria orgânica dos sedimentos foram analisados. O caranguejos (n = 957, jovens e adultos) foram classificados em: machos, fêmeas e indiferenciados; foram mensurados (Largura da Carapaça, LC) e pesados (peso úmido e seco, PS a 60 °C, 48 horas). Uma análise de correlação entre LC vs. PS foi efetuada. O crescimento morfométrico de C. granulatus foi analisado pela aplicação da função potencial (PS = a LC b), sendo que machos, fêmeas e indivíduos com sexo não diferenciado foram analisados separadamente e em conjunto. O ajuste dos dados indicou uma alometria positiva, com os machos apresentando o maior valor. Os indivíduos foram separados em coortes por meio da conversão de curvas de normalidade de uma distribuição de freqüência polimodal. Três coortes foram encontradas durante todo o período de estudo, e duas coexistindo em cada data de amostragem. Fêmeas ovígeras foram coletadas em dezembro de 2001 e 2002 e em fevereiro de 2003. Utilizou-se o método da distribuição de freqüência de tamanho para estimar a produção anual. A maior contribuição para a produção é dada pelos indivíduos sexualmente maduros, particularmente por aqueles com tamanhos entre 25 e 30 mm. A produção anual foi estimada em 7,76 g.m-2. A biomassa, expressa em peso seco, variou entre 0,55 e 1,85 g.m-2, com maiores valores registrados no outono e na primavera, e menores valores registrados no verão.

Dry season distribution of land crabs, Gecarcinus quadratus (Crustacea: Gecarcinidae), in Corcovado National Park, Costa Rica

The land crab Gecarcinus quadratus is an engineering species that controls nutrient cycling in tropical forests. Factors regulating their coastal distribution are not fully understood. We quantified land crab distribution during the dry season at Sirena Field Station in Corcovado National Park, Costa Rica, and found that land crab burrow density decreases with increasing distance from the ocean. Leaf litter depth and tree seedling density are negatively correlated with land crab burrow density. Burrows are strongly associated with sand substrate and burrow density is comparatively low in clay substrate. Results suggest that G. quadratus is limited to a narrow coastal zone with sand substrate, and this distribution could have profound effects on plant community structure.

Distribución espacial y temporal del cangrejo Callinectes sapidus (Decapoda: Portunidae) en la Bahía de chetumal, Quintana Roo, México / Temporal and spatial distribution of the crab Callinectes sapidus (Decapoda: Portunidae) in Chetumal Bay, Quintana Roo, Mexico

In order to determine temporal and spatial distribution patterns of Callinectes sapidus, samplings were carried out during the cold-front (January-February), dry (May-June) and rainy (August-September, 2002) climatic seasons, in 30 sampling stations of Chetumal Bay, grouped in sectors A (14 stations), B (eight stations) and C (eight stations). In each sampling station crabs were collected from two transects parallel to the coast, each with three traps, separated by 30 m. Sediments were calcareous coarse and medium sand, white or lightly gray. A total of 1 031 specimens were collected. CPEU (Capture Per Effort Unit) differed spatially and temporally. Highest CPEU was found in sector C with 1.3 ind.trap(-1), and in the rainy season with 1.1 ind.trap(-1). Population was predominantly composed of male individuals. The male:female ratio was 15:1. Males and adults (group II) CPEU was significant different between sectors and climatic seasons. Both males and adults (group II) had a greater CPEU in sector C (1.2 ind.trap-) and in the rainy season (1.1 ind.trap(-1)). Abundance of female and juvenile individuals (group I) was low during the sampling period whereas group 0 juvenile individuals were not found. A greater relative frequency between sectors and climatic seasons were observed in 130-139 mm and 140-149 mm size interval (CW). C. sapidus occurred on sandy sediments in Chetumal Bay. Pearson product moment correlations exhibited significant relationships between CPEU and temperature, salinity and dissolved oxygen. In Chetumal Bay, the spatial and temporal distribution of C. sapidus can be related to salinity, temperature, habitat quality, food availability, recruitment and reproduction events of individuals.

Influence of land crabs Gecarcinus quadratus (Gecarcinidae) on distributions of organic carbon and roots in a Costa Rican rain forest

In Costa Rica’s Corcovado National Park, the fossorial land crab, Gecarcinus quadratus (Gecarcinidae), densely populates (1-6 m-2) a region of forest extending from the Park’s Pacific coastline inland to ca.600 m. Throughout this coastal forest (crabzone), crabs selectively forage for fallen leaves and relocate them to subterranean burrow chambers. Comparisons between surface soils (0 -15 cm) sampled from the crabzone and forest lying immediately inland that is naturally devoid of crabs (crabless zone) suggest that crabzone top soils contained less organic carbon and fewer fine and very fine roots. In contrast, soils sampled from 70 -100 cm depths in the crabzone contained twice the carbon of the crabless zone during the dry season but similar values during the wet season. Two years of experimental crab exclusion from 25 m2 replicates established in the crabzone resulted in 16% more organic carbon content in surface soils relative to baseline conditions (n.s.) and 22% more carbon than final control values (P <0.05).Excavations of burrow chambers, with an average (±SD) depth of 48 ±12 cm, indicated localized, subterranean pockets of elevated (+60 %) organic carbon and increased densities of fine and very fine roots relative to same-depth samples from the crabzone unassociated with burrows chambers.

El cangrejo Gecarcinus quadratus (Gecarcinidae) habita madrigueras terrestres y afecta el retorno de carbón orgánico a los suelos de los bosques lluviosos al reducir la acumulación de hojarasca y alterar su proceso de descomposición. En el Parque Nacional Corcovado en Costa Rica, G. quadratus vive en altas densidades (de 1-6 cangrejos m-2) en una franja boscosa que se extiende desde la costa del Océano Pacífico hasta 600 m tierra adentro. En esta región de bosque costero (‘zona cangrejera’), los cangrejos buscan alimento selectivamente en la hojarasca, trasladando lo que recolectan a sus cuevas de más de 1 m de profundidad. Comparaciones entre la superficie de los suelos de la zona cangrejera y los de la región inmediata pero más lejana a la costa y sin cangrejos (‘zona no-cangrejera’), revelan que la capa superficial del suelo (a 10 cm) en la zona cangrejera contiene 39% menos carbono orgánico, 72% menos raíces finas y 50% menos raíces muy finas. Estos resultados contrastan con muestreos similares realizados en ambas zonas en suelos de 75-100 cm de profundidad, donde se encontraron similares concentraciones de carbono orgánico, pero la zona cangrejera tenía el doble de raíces finas y más del cuádruple de raíces muy finas que en la zona no-cangrejera. Encierros experimentales de 25 m2 realizados durante 2 a no revelaron ningún efecto de manipulación en los perfiles verticales de carbono orgánico. Sin embargo, los suelos superficiales de los encierros presentaron 18 ± 8% más carbono que los valores de control. En contraste, excavaciones en los agujeros de los cangrejos de un promedio (± SD) de profundidad de 48 ± 12 centímetros revelaron concentraciones subterráneas elevadas (+60%) de carbono orgánico con densidades elevadas de raíces finas (+1500%) y de raíces muy finas (+200%), en relación con muestras tomadas a la misma profundidad en la zona cangrejera (pero no asociadas a cuevas de cangrejos).

Study on the gill of field crab, Paratelphusa hydrodromus (Herbst.) exposed to nickel.

Paratelphusa hydrodromus (Herbst.) was exposed to 50 ppm nickel chloride solution for a period of 10 days under laboratory conditions. The gills of the treated and non-treated animals were sectioned, stained and examined under a compound microscope and noticed significant changes such as enlargement of gill lamellae, lifting up and rupture of epithelial cells, enlargement of mid rachis, hyperplasia and hypertrophy, appearance of pyknotic nuclei and a general necrosis in the treated gills. Results suggest that a comparatively low concentration of nickel (50 ppm) is enough to elicit pathological changes in Paratelphusa hydrodromus.