Microhabitat selection, and seasonal and daily activity of the snail Tikoconus costarricanus (Stylommatophora: Euconulidae) in tropical montane wet forest understory / Selección de microhábitat, y actividad diaria y estacional del caracol Tikoconus costarricanus (Stylommatophora: Euconulidae) en el sotobosque de bosques tropicales húmedos de montaña

Introduction: The integument of terrestrial mollusks is highly susceptible to dehydration; therefore, microhabitat selection, seasonality and behavior around the day are crucial to their survival. However, they are still poorly understood, especially for tropical montane wet forest species. Objetive: To analyze activity patterns and microhabitat selection on shrubs of the land snail Tikoconus costarricanus, according to season, daytime and weather. Methods: I conducted the study near "El llano" water dam in a tropical montane wet forest in Costa Rica. I observed daily activity of T. costarricanus, during the rainy and the dry season on a 2 km long trail. I observed 167 specimens and made 781 observations in total. I took note of: season, time, activity, weather, temperature and relative humidity inside the forest, and part of the leaf and height where snails were. Active snails had optical tentacles extended. I analysed daily rainfall data from a nearby meteorological station. Results: This species can be found mainly on understory leaves between 1.1 and 2 m above the floor. They are active the day around during the whole year. Only 24 % of the snails were on the upper side of leaves, but 92 % of them were active. The following behaviors were season dependent: activity peaks, leaf side selection according to daytime and weather, quantity of snails aestivating and vertical distribution. During the dry season, I found more active snails in rainy and cloudy days. During the rainy season I found more active snails in sunny days. During rainy season light hours, active snail percentage on the upper side of leaves decreased with rainfall increase, while in the dry season decreased with temperature increase and relative humidity decrease. During night hours of both seasons, the number of snails on the upper side of leaves decreased considerably in relation to active snails, especially in the rainy season. This snail aestivated on the underside of leaves during periods shorter than 21 h, mainly around noon and afternoons during the dry season. High humidity in this forest allowed snail activity around the day at any season. However, this species aestivated when moisture reached the lowest values, mainly, around noon and in the afternoons in the dry season. The rainfall pattern during the rainy season light hours explains the specimen decrease on the upper side of leaves, but in the dry season it is better explained by the temperature increase and the decrease in relative humidity. During dark hours, the almost complete snail absence on the upper side of leaves during the rainy season is explained if the effect of canopy drip produced by rain and dew condensed on leaves is added to the rain pattern. The situation is slightly different in dark hours of the dry season, in this case, snail decrease on the upper side of leaves is explained by canopy drip from dew and fog precipitation. Seasonal difference in vertical distribution may be a way to avoid rain and rain splash out on the soil. Conclusions: Moisture, temperature, rain, and canopy drip from dew, fog and rain, affect behavior and substrate selection of small terrestrial mollusks that inhabit shrubs in wet tropical rainforests.

Introducción: El integumento de los moluscos terrestres es susceptible a desecación, por eso la selección de microhábitats, la estacionalidad y el comportamiento a lo largo del día son cruciales para su sobrevivencia. No obstante, es poco lo que se ha investigado al respecto, en especial para moluscos tropicales de arbustos del sotobosque en bosques húmedos de montaña. Objetivo: Analizar los patrones de actividad y de la selección de microhábitats del caracol terrestre Tikoconus costarricanus según la estación del año, la hora del día y el clima. Métodos: El trabajo lo realicé en un bosque tropical húmedo de montaña cerca de la represa hidrológica "El Llano", Costa Rica. Analicé la actividad diaria de especímenes de T.costarricanus en un trayecto de 2 km: observé 167 especímenes e hice 781 observaciones. Tomé nota de: estación del año, hora, actividad, parte de la hoja donde estaba el caracol, altura en la planta, clima y humedad relativa y temperatura dentro del bosque. Consideré que un espécimen estaba activo cuando los tentáculos ópticos estaban extendidos. Analicé la precipitación pluvial por horas con datos de una estación meteorológica cercana. Resultados: Encontré caracoles principalmente en las hojas de arbustos entre 1.1 y 2 m sobre el suelo; encontré individuos activos a todas horas y en cualquier época del año. Solo el 24 % de los individuos estaban en el haz, de esos el 92 % estaban activos. Encontré variación estacional en el patrón de actividad, la selección del lado de la hoja de acuerdo a la hora del día y el clima, la cantidad de especímenes estivando, y la distribución vertical. En la época seca encontré más caracoles activos con clima húmedo, por el contrario, en la estación lluviosa encontré más caracoles activos con clima seco. Durante las horas de luz de la estación lluviosa, la cantidad de caracoles activos sobre el haz de las hojas disminuyó con el aumento de precipitación pluvial, en tanto que en la estación seca disminuyó con el aumento de la temperatura y la disminución de la humedad relativa. Durante las horas nocturnas de ambas estaciones, la cantidad de caracoles sobre el haz de las hojas disminuyó considerablemente en relación a los caracoles activos, especialmente en la época lluviosa. Este caracol estivó principalmente a mediodía y en las tardes de la época seca en el envés de las hojas por periodos inferiores a 21 h seguidas. La elevada humedad del bosque tropical húmedo de montaña permite que estos caracoles estén activos en cualquier momento. Sin embargo, la estivación les permite protegerse de la desecación durante los periodos más secos. El patrón de lluvias durante las horas de luz de la época lluviosa explica la disminución de especímenes presentes en el haz de las hojas, pero en la época seca lo explica mejor el aumento de la temperatura y la disminución de la humedad relativa. Durante las horas oscuras, la casi ausencia de caracoles en el haz de las hojas durante la estación lluviosa se explica si al patrón de lluvia se le agrega el efecto del goteo foliar producido por la lluvia y el rocío que se condensa sobre las hojas. La situación es un poco diferente en las horas oscuras de la estación seca, en este caso, la disminución de caracoles en el haz, se explica por el goteo foliar derivado del rocío y de la precipitación de neblina. Es posible que la diferencia en la preferencia vertical se deba a que evitan la lluvia y la salpicadura de la lluvia al caer en el suelo. Conclusiones: La humedad, la temperatura, la lluvia y el goteo foliar derivado de rocío, neblina y lluvia, afectan el comportamiento y la selección de sustrato de moluscos terrestres pequeños que habitan en arbustos de bosques tropicales húmedos de montaña.

Histological validation of morphochromatically-defined gonadal maturation stages of green abalone (Haliotis fulgens) Philippi,1845 and pink abalone (Haliotis corrugata) Wood, 1828 / Validación histológica de las fases morfocromáticas de maduración gonádica del abulón azul (Haliotis fulgens) Philippi, 1845 y del abulón amarillo (Haliotis corrugata) Wood, 1828

Identifying the maturity stage of specimens is essential for the determination of the spawning season, which in turn facilitates the formulation of adequate fisheries management measures for the sustainable use of sea resources, such as abalone. This study aims to validate, based on histological evidence, a gonad maturation scale that encompasses four morphochromatically-defined stages (developing, maturity, spawning and resting) for females and males, plus an additional stage for reproductively inactive (undifferentiated) specimens, to be used as an identification key. Given the similarity between Haliotis fulgens and Haliotis corrugata as to their morphochromatic features, the gonadal maturation scale can be used for both species.

La determinación de la fase de madurez es importante para identificar la temporada de desove y permitir establecer medidas de manejo pesquero para el aprovechamiento responsable de los recursos como el abulón. El presente trabajo valida histológicamente una escala de maduración gonádica a manera de guía de identificación, que consiste de cuatro fases morfocromáticas para hembras y machos (desarrollo, madurez, desove y reposo), y un estadio para los organismos reproductivamente inactivos (indiferenciado). Dada la similitud entre las características morfocromáticas de Haliotis fulgens y Haliotis corrugata, la escala de maduración gonádica puede ser utilizada indistintamente.

Estudios de diversidad en comunidades de moluscos fluviales de importancia médica / Diversity studies in freshwater mollusc populations of medical importance

Introducción: se realizó un estudio ecológico sobre la diversidad en poblaciones de moluscos de importancia médica, para mostrar la importancia de los cambios en la diversidad sobre el comportamiento de estas en diferentes ecosistemas. Objetivo: determinar qué cambios en las abundancias de las poblaciones hacían que variara la diversidad. Métodos: se evaluaron 5 localidades en las provincias habaneras para determinar los cambios en la Beta diversidad. Resultados: el valor normal de variación de la diversidad para las comunidades de moluscos parece ser de 5 a 6 por ciento, mientras que los mayores valores fueron obtenidos en lugares con cambios drásticos en el ecosistema. Solo una localidad manifestó un valor muy bajo porque las fluctuaciones de la diversidad dependían de 2 especies. En los lugares donde existieron especies altamente dominantes la diversidad fue menor por un descenso en la equitatividad entre las especies presentes y no en la riqueza del lugar. Conclusiones: los cambios de la diversidad son tan importantes como las fluctuaciones de los factores ambientales y muchas veces tienen incidencias más marcadas sobre la dinámica de las comunidades de especies hospederas intermediarias.

Background: An ecological study was carried out on the diversity of freshwater mollusc populations of medical importance to show the significance of changes in diversity for their behaviour in various ecosystems. Objective: to determine what changes in the abundance of the populations were responsible for diversity variations. Methods: Five locations were evaluated to obtain monthly changes in diversity (Beta-diversity). Results: the normal value for diversity change in mollusc communities was around 5-6 percent whereas the highest values were seen in locations where dramatic changes in the ecosystem had occurred. Only one location showed a very low value because diversity fluctuations depended merely on two species. In those places with highly dominant species, diversity was low due to less equity in the amount of present species and not to a reduction in species richness. Conclusions: Diversity changes can be as important as the environmental fluctuations and usually have marked effects in the dynamics of intermediary host species populations.

Estructura de la comunidad de moluscos y relaciones tróficas en el litoral rocoso del estado Sucre, Venezuela / Structure of the mollusk community and trophic relationships in the rocky coast of Sucre state, Venezuela

Mollusc community structure and trophic relations in the rochy littoral zone in Sucre State, Venezuela. We analyzed the structure of a mollusc community and its component trophic relations at six localities within a rocky littoral zone, in Sucre State, Venezuela, including areas that are both exposed to, and protected from, wave energy. Sampling was carried out from March 2003 to Febreuary 2004 period, in an area subdivided in to supralittoral, littoral and sublittoral zones. Samples were collected using hand-held spoons within 0.25 m² quadrats along transects sited perpendicular to the coast line transects. Collected organisms were preserved in 10% formalin for subsequent taxonomic classification. Specific richness and constance were determined, and the four trophic categories of herbivore, suspendivore, carnivore and herbivore-suspendivore were established. Overall 14 581 individual specimens were collected that represented 68 species, 31 families and 9 orders, in the classes Gasteropoda (n=39), Bivalvia (n=23) and Polyplacophora (nn=6). Suspension feeders were the dominant trophic category (49%), followed by carnivores (337%), herbivores (13%) and herbivores-suspension feeders (11%). Herbivores and suspension feeders were dominant in the protected area, while carnivores and suspension feeders were dominant in the exposed area. Data indicate that mollusc distribution and intergroupal trophic relations are controlled by both morphological features and substrate composition. Rev. Biol. Trop. 54 (Suppl. 3): 121-130. Epub 2007 Jan. 15.

Se analizó la estructura de la comunidad de moluscos y sus relaciones tróficas en seis localidades del litoral rocoso con diferentes grados de exposición al oleaje (área expuesta y área protegida), en el Estado Sucre, Venezuela. El muestreo se llevó a cabo durante el período de marzo 2003 a febrero 2004. La recolección del material biológico se realizó de forma manual con ayuda de una espátula, dentro de una cuadrícula de 0.25 m², estableciéndose tres zonas: supra, medio e infralitoral. Los organismos fueron preservados en frascos con formalina al 10% para su posterior análisis. En el laboratorio fueron identificados, contados, y pesados en una balanza de 0.001g de precisión. Se determinó la abundancia total de especies, biomasa, constancia específica y por medio de una revisión bibliográfica se le asignó a cada especie su categoría trófica, clasificándolos en: herbívoros, filtradores, carnívoros y herbívoros -filtradores. Se obtuvo un total de 14 581 individuos (6 397.945 g) representado por 68 especies correspondientes a las clases Gastropoda (39), Bivalvia (23) y Polyplacophora (6); contenidas en nueve órdenes y 31 familias. Los herbívoros fueron el grupo dominante (49%), seguido por filtradores (37%), carnívoros (13 %) y herbívoros-filtradores (1%). Las especies herbívoras y herbívoras-filtradoras dominaron en el área protegida, mientras que en el área expuesta, fueron las carnívoras y filtradoras. Las especies constantes en las seis localidades durante el período de estudio fueron Planaxis nucleus, Mitrella ocellata, M. nycteis, Littorina interrupta, Tegula fasciata, Acmaea leucopleura, Ostrea equestris y Chiton squamosus. La distribución de los moluscos y los diferentes grupos tróficos, pueden estar controlados por adaptaciones morfológicas, así como el nivel de exposición al oleaje y composición del sustrato.

Applying weight gain in Pomacea lineata (Spix 1824) (Mollusca: Prosobranchia) as a measure of herbicide toxicity

Pomacea lineata, um molusco amplamente distribuído e considerado como peste em plantações de arroz no Oriente, pode ser considerado como um valioso recurso para monitorar a qualidade da água no Nordeste do Brasil. Neste trabalho, apresentamos dados que demonstram que o incremento de peso em moluscos neonatos é uma medida consistente que responde eficientemente ao estresse imposto por concentrações tóxicas subletais dos herbicidas Paraquat e Round-up. Os resultados de crescimento para avaliar a toxicidade crônica foram obtidos em experimentos de quatro e quatro, oito, doze e dezesseis dias para Paraquat e Round-up, respectivamente. A maior concentração de efeito não observado (NOEC) e a menor concentração de efeito observado (LOEC) para Paraquat, após 96 horas, foram respectivamente de 0,12 e 0,25 mg/L. Para o Round-up, os valores de NOEC e LOEC estimados foram respectivamente de 0,25 e 0,5 mg/L. Todas as concentrações de Round-up testadas após 192 horas de exposição provocaram diminuições nas taxas de crescimento, sendo significativamente diferentes do controle. Conseqüentemente não pode ser estimado o valor de NOEC. O valor de LOEC foi menor do que 0,12 mg/L. Além disso, não houve nenhuma mortalidade durante o teste. Por conseguinte, nenhum NOEC pôde ser derivado e o LOEC era < 0,12 mg/L. Para as mais baixas concentrações de Paraquat testadas (0,005 mg/L), houve um aumento do crescimento que foi significativamente maior que o controle, sugerindo a ocorrência de um efeito hormético.

Abundancia y morfometría de Anadara tuberculosa y A. similis (Mollusca: Bivalvia) en el Manglar de Purruja, Golfo Dulce, Costa Rica / Abundance and morphometry of Anadara tuberculosa and A. similis (Mollusca: Bivalvia) in the Manglar de Purruja, Dulce Gulf, Costa Rica

The density, population, length, yield and sex proportion of the mollusks Anadara tuberculosa and A. similis were studied in Bahía de Golfito, Golfo Dulce, Pacific coast of Costa Rica from February 1998 to February 1999. A. tuberculosa was more abundant (0.9 units m(-2)), than A. similis (0.2 units m(-2)); the highest abundance was found at the canal mouths. The average lengths were 43.3 mm for A. tuberculosa and 42.8 mm for A. similis (both under the Costa Rican legal minimal length for exploitation: 47 mm). Maximum lengths were measured in the middle and upstream Canal Mayor, respectively: 43.0 mm and 43.4 mm. The correlation between length and fresh weight was 0.81 (Pearson). The average total weights were 26.2 g for A. tuberculosa and 19.1 g for A. similis. The condition index (a meat yield measurement) was higher in A. similis (21.2%) than in A. tuberculosa (17.2%). The maximum yield for both species lies in the 31-35 mm range. The male ratio was 43.7%. A species recovery plan is urgent because these results suggest both a decrease in density and illegal exploitation.

Avaliaçäo da esquitossomose e de outras parasitoses intestinais, em escolares do município de Bambuí, Minas Gerais, Brasil / Evaluation of the schistosomiasis and others intestinal parasitosis in the school children of Bambuí county, Minas Gerais, Brazil

O objetivo desse trabalho foi determinar a prevalência das parasitoses em escolares de Bambuí, através de exames coprológicos (direto e Kato-Katz) e reavaliar os criadouros de moluscos descritos no município. Dos 2.901 escolares examinados, 20,1 por cento estavam parasitados, sendo que Giardia lamblia, Entamoeba coli, Ascaris lumbricoides e ancilostomídeos foram os parasitas mais freqüentes, com prevalências de 6,2 por cento, 6,2 por cento, 4,8 por cento e 1,4 por cento, respectivamente. Os ancilostomídeos foram significativamente mais freqüentes na zona rural e nos alunos com mais de 14 anos, enquanto a prevalência da E. coli foi maior na zona urbana e a G. lamblia mais freqüente na faixa etária de 0-6 anos. Somente três crianças eliminavam ovos de Schistosoma mansoni. O único hospedeiro intermediário encontrado foi a Biomphalaria glabrata e nenhuma delas estava eliminando cercárias de S. mansoni. Comparando-se estes dados a de levantamentos raalizados anteriormente no município, observou-se uma queda na prevalência de todos os parasitas. Algumas hipóteses para tentar explicar esta queda säo discutidas tais como: processo intenso de unbanizaçäo e a melhoria das condiçöes sócio-sanitárias do município

Synchronized order of appearance of hyaluronic acid (or acidic galactan)-->chondroitin C6 sulfate-->chondroitin C-4/C-6 sulfate, heparan sulfate, dermatan sulfate-->heparin during morphogenesis, differentiation and development

The synthesis of glycosaminoglycans and acidic polysaccharides during embryonic and fetal development in mammals and molluscs is briefly reviewed. A sequential order of appearance of each of the acidic polysaccharides was observed, coinciding with the major processes of the ontogeny. In mammals, hyaluronic acid is the first glycosaminoglycan synthesized at the beginning of morphogenesis. This glycosaminoglycan is then replaced by chondroitin 6-sulfate during the migration of the mesenchymal cells. Heparan sulfate, dermatan sulfate and chondroitin 4-sulfate are synthesized only during cell differentiation. The synthesis of heparin, on the other hand, is confined to mast cells in a few tissues and is a late event in the differentiation process. The same general pattern is also observed in molluscs except that hyaluronic acid is replaced by an acidic galactan in the morphogenetic process. The activity of the degrading enzymes responsible for the disappearance of hyaluronic acid, chondroitin sulfate and the acidic galactan in each phase of embryonic development is also reviewed.

Cultivo de Pomacea sordida (Swainson, 1823) em Cativeiro / Culture of Pomacea sordida (Swaison, 1823) in Captivity

Estabelecidas as condições necessárias para a reprodução e o desenvolvimento em laboratório de Pomacea sordida (Swainson, 1823), apresentamos os dados relativos à criação intensiva deste molusco. Estudos de alimentação demonstraram as preferências dos animais jovens (3, 6 e 9 mm). No estabelecimento de curvas de crescimento, foram utilizados alface e rami, por serem estes os alimentos mais bem aceitos pelos animais menores. A conversão média foi de 6g de alimento por grama de crescimento. Gráficos relativos ao consumo de oxigênio indicam que a densidade populacional aceitável foi de 1.000 animais por m2 com 10 mm (4cm2 de superfície de tanque por animal). A continuação deste estudo se faz necessário a fim de determinar a viabilidade econômica do processo e a natureza química do produto.

The growth conditions for Pomacea sordida in the laboratory were established. Various sources of feeding were tested and lettuce proved to be the best for the young mollusks. To the bigger ornes than 6 mm rami was an inexpensive foodstuff. Results related to the oxygem consumption indicated that the available density was 1.000 animais per m² and the best body length for the specimens should be 10mm. Our results suggest thar this animal could be raised as a source of animal protein for animal feeding. A continuation of study is necessary in order to determine the economical viability of the process and the chemical composition of the product.

Comparación del crecimiento de 2 especies de pomacea del áerea antillana, útiles como agente de control de enfermedades tropicales / Comparison of the growth of 2 pomacea species of the caribbean áerea, useful as agent for the control of tropical diseases

Se presenta un estudio comparativo del crecimiento de 2 especies de Pomacea(P.glauca y P.paludosa) del áerea de Las Antillas. Se observa que aparecen diferencias ecológicas reflejadas en los paramétros de crecimiento. Estas divergencias pueden estar influidas por las diferencias en las condicionesfísico-químicas y ambientales de las localidades de estudio, pero puede apreciarse una clara diferencia ecológica entre ambas especies.Los parámetros de crecimiento(K y Lè),así como las curvas de crecimiento,reflejan que son especies de crecimiento lento con un rango de vida corto,las especies de Pomacea,pueden mantener poblaciones estables en cuerpos de agua permanente,lo cual significa una ventaja importante como agentes de control biológico

Aspectos biotecnológicos en larvas de "loco" / Biotechnological aspects in \"locus\" larvae

The biology of planktotrophic larvae of Concholepas concholepas is the main bottleneck towards developing biotechnologies to rear this muricid. Data concerning planktonic larvae development, diets and environmental signals triggering larval settlement and recuitment is scarce. We have begun the study of the molecular and cell biology of embryos, larvae and recruits having as a final goal, the development of appropriate biotechnologies to rear this gastropod. First, an inverse ratio between BuChE and AChE enzyme activities was established. This ratio may be a precise development marker for this species. Second, for the first time a phosphoinositide rlated regulatory pathway is reported in a muricid, opening a new approach to the biotechnological management of larvae. Third, the relation between sulfate in sea water and larval motility was studied. Concentration below 125 µM sulfate decreases larval motility. The sulfate is incorporated in proteoglycans which participate in different developmental phenomena. Lastly, a genomic Concholepas concholepas DNA sequence, similar to that of a human growth hormone probe was detected. This is very interesting since growth factors are key molecules during development, growth and are involved in food conversion rares in fishes and also, a in variety of marine invertebrates