Evaluation of an alternative technique for preserving crustaceans in dry conditions with joint mobility: a proposal for didactic purposes

Although crustaceans are traditionally preserved in liquids (formaldehyde and/or ethyl alcohol), those substances tend to alter their morphological aspects. Glycerin, used in human anatomy, is considered a good substitute for formaldehyde, as it preserves animals in states similar to in vivo conditions. There are no records in the literature, however, concerning the use of glycerin for conserving invertebrates. The objective of this work was to elaborate and evaluate alternative techniques for conserving the crustacean Ucides cordatus (Linnaeus, 1763). Six fixatives (1, 3, 4 and 5% formaldehyde, 70% alcohol, and dietrich solution) and two controls (positive and negative) were tested, as well as the effects of freezing before fixation on the integrity of U. cordatus specimens. Our results were evaluated with respect to nine variables. The treatments that demonstrated the best aesthetic results were 4% formaldehyde and 70% ethyl alcohol. The freezing of the animals resulted in brittle organs in all treatments tested. The technique discussed here is extremely promising for the conservation of animals for educational purposes, as it produces preserved specimens that are aesthetically similar to their in vivo conditions.

Cultivo de larvas de Ucides cordatus (LINNAEU, 1763) sob diferentes intensidades luminosas / Rearing of Ucides cordatus (LINNAEU, 1763) larvae under different light intensities

O caranguejo-uçá, Ucides cordatus, é uma espécie típica dos manguezais brasileiros e tem grande importância econômica para as populações litorâneas tradicionais. O presente trabalho investigou a influência da intensidade luminosa sobre a sobrevivência e a taxa de desenvolvimento larval de U. cordatus. Três intensidades luminosas foram avaliadas: claro - 710 lux, penumbra - 210 lux e escuro - 1 lux, em duas condições de cultivo, individual e coletivo. Houve diferenças significativas entre as taxas de sobrevivência das larvas zoea e as três intensidades luminosas avaliadas (p<0,05). As maiores taxas de ecdise para o estágio de megalopa foram obtidas no tratamento claro (42% nos cultivos coletivos e 30% nos cultivos individuais). No tratamento escuro, a metamorfose para megalopa foi de apenas 16% nos cultivos coletivos e de 7% nos cultivos individuais. Estes resultados indicam que a manutenção das larvas em baixas intensidades luminosas afeta negativamente a sobrevivência larval de U. cordatus...

Ucides cordatus is an edible crab species typical of Brazilian mangroves, and traditionally represents an important economic resource for many coastal populations. The present study investigated the influence of light intensity on the survival and rate of larval development of U. cordatus. Three different levels of luminosity were evaluated: 710 (Light), 210 Lux (Shaded) and 1 Lux (Dark), both in individual and collective cultivation conditions. Significant differences were found for survival of zoea larvae under the different light intensities (P<0.05). The greatest survival rates as well as rates of ecdysis to the megalopa stage were obtained under Light conditions (42% in collective cultures and 30% in individual cultures). In Dark conditions events of metamorphosis to megalopa stage was observed only in 16% of collective cultures and 7% of individual cultures. The result indicates that low light intensities may negatively affect larval survivorship during U. cordatus larval cultivations...

Comparison of three quick methods to estimate crab size in the land crabs Cardisoma guanhumi Latreille, 1825 and Ucides cordatus (Crustacea: Brachyura: Gecarcinidae and Ucididae) / Comparación de tres métodos rápidos para estimar el tamaño del cangrejo en los cangrejos terrestres Cardisoma guanhumi Latreille, 1825 y Ucides cordatus (Crustacea: Brachyura: Gecarcinidae y Ucididae)

Quick, reliable and non destructive methods are necessary to estimate size structure on commercial land crabs, in order to acquire relevant information concerning the health of their populations. Cardisoma guanhumi and Ucides cordatus are two land crabs that are exploited at a high scale and also in an artisan way in the Caribbean area and in the coasts of Brazil, which populations are endangered due to uncontrolled exploitation. The purpose of this work is to provide various methods to estimate indirectly crab body size. Sampling was carried out in Carenero (C. guanhumi) and Cumaná (U. cordatus) (Venezuela). For each species, three methods were used to measure burrow diameter (Vernier, internal spring caliper and photograph), and these were correlated with real body size of the crabs. Model II linear regression analyzes, i.e. Ordinary Least Squares and Mayor Axis, were used to build and test the performance of forecasting models. Cardisoma guanhumi showed a high bivariate data dispersion using Vernier and photo measuring methods, increasing these towards larger animals. Less dispersion was achieved with the spring caliper method; this resulted in the most accurate measurements of indirectly estimated body size in C. guanhumi (r²= 0.61), whereas Vernier measurements were the least precise. On the other hand, all three methods gave reliable estimates for U. cordatus, being the Vernier method the most accurate (r²= 0.71). However, in both species, all forecasting equations overestimated the size of smaller crabs (those below the mean) but underestimated the size of larger crabs. Nevertheless, all three methods were statistically significant for each of the species, and looking at the above mentioned underand overestimations, they can serve as reliable and fast non-destructive tools to be used by resource managers and field biologists to acquire size structure information concerning these two species. Vernier and internal spring caliper ...

Para la estimación de la estructura de tamaños en cangrejos terrestres comerciales y la obtención de información relevante para su manejo, es necesario utilizar métodos rápidos, confiables y no destructivos. Cardisoma guanhumi y Ucides cordatus son dos cangrejos terrestres que son explotados comercialmente en el Caribe y en Brasil. El propósito de este trabajo es suministrar métodos indirectos para la estimación del tamaño del caparazón de los cangrejos y por consiguiente, de la estructura de tallas. Los muestreos se llevaron a cabo en Carenero (C. guanhumi) y en Cumaná (U. cordatus) (Venezuela). Se utilizaron tres métodos para estimar el diámetro de sus madrigueras: Vernier, compás y fotografía. Estos se correlacionaron con el tamaño real del cangrejo. Se aplicó el análisis de regresión Ordinary Least Squares Model II y la capacidad de predicción se probó utilizando el modelo II Mayor Axis para las regresiones. Cardisoma guanhumi mostró una fuerte dispersión de sus datos en los métodos de Vernier y fotografía. Menos dispersión se obtuvo con el método del compás y fue el más preciso (r²= 0.61). Para U. cordatus las medidas con Vernier fueron la más adecuadas (r²= 0.71). Sin embargo los tres métodos fueron confiables. Los diferentes métodos mostraron ventajas y desventajas y dependerá del que aplique los métodos, decidir cuál será el más adecuado para sus propósitos.

The abundance of some pathogenic bacteria in mangrove habitats of Paraiba do Norte estuary and crabmeat contamination of mangrove crab Ucides cordatus

Study on mangrove water and sediment of Paraiba do Norte river (Northeastern Brazil) and crabmeat of Ucides cordatus was carried to investigate the relation between the abundance of bacteria in the mangrove habitat and in the crabmeat. Simultaneous collection of samples of water, sediment and crabs (U. cordatus) was done during the rainy and dry seasons at two areas of mangroves that differed in influence of tide and sewage discharge. The numbers of total heterotrophic bacteria in the mangrove water were between 0.04 and 6 log CFU 100mL-1, and in the sediment between 5 and 6 log CFU g-1. The location closer to waste discharge showed higher incidence of total heterotrophic bacteria, coliforms, Staphylococcus aureus and Salmonella spp. The counts of total heterotrophic bacteria in the crabmeat varied from 1.3 to 4.4 log CFU g-1, and did not differ significantly between the locations analysed. No crabmeat sample showed the presence of coliforms, S. aureus and Salmonella spp.

O estudo sobre água e sedimento do mangue do rio Paraíba do Norte (Nordeste do Brasil) e carne de caranguejo-uçá (Ucides cordatus) foi conduzido para investigar a relação entre a abundância de bactérias heterotróficas totais e patogênicas no ambiente e na carne de caranguejo. As amostras de água, sedimento e caranguejos U. cordatus foram coletadas simultaneamente em duas áreas do manguezal que diferiam em influencia da maré e do esgoto lançado no mangue. O número de bactérias heterotróficas totais nas amostras de água do mangue variaram de 0,04 a 6 log UFC 100mL-1, e no sedimento de 5 a 6 log UFC g-1. Em local mais próximo a desembocadura do esgoto evidenciou-se maior incidência de bactérias heterotróficas totais, coliformes, Staphylococcus aureus e Salmonella spp. As contagens de bactérias totais nas amostras da carne de caranguejo variaram de 1,3 a 4,4 log UFC g-1, não diferindo estatisticamente entre as áreas estudadas. Nenhuma amostra da carne de caranguejo apresentou coliformes, S. aureus e Salmonella spp.

Length-weight relationship and condition factor of the mangrove crab Ucides cordatus (Linnaeus, 1763) (Crustacea, Brachyura, Ucididae)

The relationship of wet weight (WT) to cephalothorax width (CW) and temporal and seasonal variations in the condition factor were analyzed for each sex of the mangrove crab Ucides cordatus, using specimens collected monthly from September 1998 through September 2000, at Iguape, state of São Paulo. The WT/CW relationship, determined by the regression analysis and the condition factor were evaluated individually, monthly and seasonally, for each sex. The WT/CW relationship indicated isometric growth in males and negative allometric growth in females. Body weight was higher in males than in females of equivalent size and this difference was associated with the males' faster growth and heavier chelipeds. On the other hand, the means for condition factor were always higher for females than for males; the mean condition factor was lower in spring and summer and higher in autumn and winter.

A determinação da relação do peso úmido (WT) pela largura cefalotorácica (CW) do caranguejo U. cordatus e a análise da dinâmica temporo-sazonal do fator de condição foram realizadas com machos e fêmeas coletados mensalmente no período de 1998/2000, em Iguape (SP). A relação WT/CW foi determinada por análise de regressão, enquanto o fator de condição foi determinado individualmente para cada animal, bem como pela média mensal e sazonal para cada sexo. A relação WT/CW evidenciou um crescimento isométrico nos machos e alométrico negativo nas fêmeas, indicando que os machos atingem um peso corpóreo superior ao das fêmeas para um mesmo tamanho de referência. Tal fato está associado ao maior crescimento e peso dos quelípodos do macho. As médias do fator de condição das fêmeas foram maiores que as dos machos. Os menores valores do fator de condição ocorreram durante a primavera e verão, atingindo os maiores níveis durante o outono e inverno.

Duration of the pre-settlement period of the mangrove crab Ucides cordatus (Decapoda: Ocypodidae) under laboratory conditions

The goal of the present study was to determine the most appropriate time to release the immatures of Ucides cordatus (Linnaeus) produced in the laboratory into the natural environments. Specifically, the time when the megalopae sought the mangrove sediment to excavate the burrows was determined, as well as the time necessary for their metamorphosis into the first juvenile stage. Results indicated that the megalopae of U. cordatus reared in the laboratory took three to ten days (median = 6) after their molt to excavated burrows in the sediment. The average time for the megalopae to molt into juveniles was 12.6 days (SD = 2.3).

O estágio de desenvolvimento em que se encontram as formas jovens de caranguejo produzidas em laboratório, no momento da sua liberação para o ambiente, é um fator chave para o sucesso dos trabalhos de repovoamento. O presente trabalho teve como objetivo determinar a idade mais adequada das formas jovens de U. cordatus, produzidas em laboratório, para sua liberação no ambiente natural. Especificamente, o momento em que as megalopas procuram o sedimento de mangue para escavar tocas foi determinado, assim como o tempo que demoram até realizarem a metamorfose para o primeiro estágio juvenil. O experimento indicou que as megalopas de U. cordatus produzidas em laboratório levam de 3 a 10 dias (mediana = 6) após a metamorfose até escavarem tocas no sedimento. O tempo médio que as megalopas levaram até realizar a metamorfose para o primeiro estágio juvenil foi de 12,6 dias (desvio padrão = 2,33).

O efeito da salinidade no desenvolvimento larval do caranguejo - uçá, Ucides cordatus (Linnaeus, 1763) (Decapoda: Ocypodidae) no Norte do Brasil / The effect of salinity on the larval development of the uçá-crab, Ucides cordatus (Linnaeus, 1763) (Decapoda: Ocypodidae) in Northern Brazil

O presente trabalho estudou o efeito da salinidade na sobrevivência e na duração do desenvolvimento larval do caranguejo-uçá, Ucides cordatus (do estuário do Rio Caeté, Norte do Brasil), até a fase de megalopa em sete tratamentos de salinidade (0, 5, 10, 15, 20, 25 e 30). A salinidade afetou significativamente a sobrevivência das larvas zoea, no entanto não afetou a duração do desenvolvimento larval (20,77 ± 1,56 dias). Nas salinidades 0, 5 e 10 houve total mortalidade das larvas zoea. Somente a partir da salinidade 15 observou-se um desenvolvimento completo até a fase de megalopa. A taxa de sobrevivência foi maior em salinidade 30 (72 por cento) e menor em 15 (16 por cento). A reduzida taxa de sobrevivência das larvas zoea de U. cordatus, em salinidades baixas, indica a necessidade de dispersão larval do estuário para as águas costeiras onde as condições de salinidade para o desenvolvimento larval são mais favoráveis. Caso contrário se não houvesse a dispersão, a reduzida salinidade das águas estuarinas no período chuvoso, causaria uma elevada mortalidade, afetando desta forma o recrutamento, a manutenção e o crescimento da população de U. cordatus nos manguezais.

The present work studied the effect of salinity on the survival and duration of larval development of the mangrove crab, Ucides cordatus (from the Caeté River estuary, North of Brazil) until the megalopal phase in seven salinity treatments (0, 5, 10, 15, 20, 25 e 30). Salinity significantly affected the survival of the zoea larvae, however it did not affect the duration of the larval development (20.77 ± 1.56 days). In salinity 0, 5 and 10 all zoea larvae died. Only from off salinity 15, complete development until the megalopal phase occurred. The survival rate was highest in salinity 30 (72 percent) and lowest in 15 (16 percent). The reduced survival rate of the U. cordatus zoea larvae, in low salinities, indicates the necessity of larval dispersion from the estuary to coastal waters, where salinity conditions for larval development are more favorable. Otherwise, if there was no dispersion, the reduced salinity of estuarine waters in the rainy season would cause a high mortality thereby affecting the recruitment, maintenance and growth of the U. cordatus population in the mangroves.