Distribution and density of the bivalve Anomalocardia brasiliana in the estuarine region of Northeastern Brazil / Distribuição e densidade do bivalve Anomalocardia brasiliana em região estuarina do semiárido do Nordeste do Brasil

Abstract The objective of this study was to analyze the density and distribution of the bivalve Anomalocardia brasiliana in beaches in the estuarine region of the semiarid in Rio Grande do Norte State, Barra and Pernambuquinho (04°56.978'S and 37°08.961'W and 04°56.792'S and 37°09.375'W, respectively). Samples were collected monthly during 37 months using five transects (300 m long and 400 m apart) laid perpendicularly to the beach line toward the sea. Seven collection points, 50 m apart, were set in each transect, and shellfish and sediment samples were collected. Temperature and salinity were measured in each transect. The results showed a temperature variation of average values ​​of 3 °C; the greatest variation (33.2 °C) was observed in May of 2009. The lowest average salinity values were observed between April and June of 2009 (5, 8.7, and 7.8, respectively). This fact was due to an atypical rainfall in the region, which resulted in a large freshwater inflow into the estuary; the average salinity values ​​were about 40 in the remaining months. The highest precipitation values were observed in April/09, April/10, and April/11; the highest precipitation occurred in April/09 (316.3 mm). The lower average densities of A. brasiliana were observed in April and May/09 when compared to the other months; the lowest value was observed in April/09 (26 ind/m2). The highest densities occurred between November/10 and July/11, with values ​​ranging from 70 to 322 ind/m2. The highest inflow of young individuals (lengths from 2 to 5 mm) was observed between April and June of 2010 and on September/10 while the highest frequency of adults (from 20 to 25 mm) occurred between December of 2010 and April of 2011. Hence, the results of this study show that in the months with the greatest rainfall, salinity and the average density of A. brasiliana showed the lowest values.

Resumo O objetivo do trabalho foi analisar a densidade e distribuição do bivalve Anomalocardia brasiliana em praias de uma região estuarina do semiárido do Rio Grande do N (Barra - 04°56,978'S, 37°08,961'O e Pernambuquinho - 04°56,792'S, 37°09,375'O). As coletas foram realizadas durante 37 meses (abril/09 a abril/12). Mensamente foram dispostos cinco transectos (300 m de comprimento e distanciando 400 m entre si, perpendicularmente à linha da praia em direção ao mar. Em cada transecto foram definidos sete pontos de coletas com distância de 50 m entre si e coletadas amostras de moluscos e sedimento. Em cada transecto aferiu-se a temperatura e salinidade da água. Os resultados mostraram que houve uma variação dos valores médios de temperatura de 3°C, sendo o mês de maio/09 ocorreu o maior valor dessa variável (33,2 °C). Quanto aos valores médios de salinidade, o período de abril a junho/09 apresentou-se os menores valores médio da salinidade (5, 8,7 e 7,8, respectivamente), tal fato ocorreu, devido a um período de chuvas atípicas na região, que resultou em um grande aporte de água doce no estuário, nos demais meses os valores médios da salinidade foram cerca de 40. Ao analisar a precipitação observou-se, que os maiores valores ocorreram nos meses de abril/09, abril/10 e abril/11, sendo que o maior valor da precipitação ocorreu no mês de abril/09 (316,3 mm). As densidades médias de A. brasiliana nos meses de abril e maio/09 foram menores quando comparadas as densidades médias dos demais meses, sendo que o menor valor foi observado no mês de abril/09 (26 ind/m2). As maiores densidades ocorreram no período de novembro/2010 a julho/2011, com valores variando de 70 a 322 ind/m2. No período de abril a junho de 2010 e no mês de setembro/10 foi observada uma maior entrada de indivíduos jovens (comprimentos entre 2 a 5 mm), enquanto que durante o período de dezembro/2010 a abril/2011 ocorreu uma maior frequência de indivíduos adultos (entre 20 a 25 mm). Assim verificou-se com o presente estudo que, nos meses que ocorreram maior precipitação, salinidade e densidade média de A. brasiliana foi menor.

Phytoplankton composition of the water and gastrointestinal tract of the mussel Diplodon enno (Ortmann, 1921) from São Francisco river (Bahia, Brazil) / Composição fitoplanctônica da água e do trato gastrointestinal do molusco Diplodon enno (Ortmann) do rio São Francisco (BA - Brasil)

Abstract The knowledge on diet composition of the freshwater mussel Diplodon enno (Ortmann) would aid in its culture and propagation allowing, this way, the replacement of natural endangered populations in Brazil. Microalgae are the main food source for captive mussels and unionids have displayed an ability to sort algae based on the cellular characteristics prior to ingestion. The main objective of the present work is to analyze the phytoplankton composition of the water from and of the gastrointestinal contents of the mussel D. enno, as an initial step for development of a suitable rearing diet. Therefore, water samples and bivalve specimens were collected from S. Francisco River, city of Paulo Afonso, Bahia, Brazil. The microalgal composition found in water and stomach/gut content samples was very diverse being represented by the following divisions: Cyanophyta, Chlorophyta, Dinophyta and Heterokontophyta (Diatoms). Concerning the relative abundance of microalgae divisions, it is possible to state, for the water and gastrointestinal contents, that Cyanophyta represents 15% and 14%, Chlorophyta 54% in both, Heterokontophyta 31% and 27% and Dinophyta 0% and 5%, respectively. According to the Brazilian CETESB criteria for phytoplankton species classification, 50% of Cyanophyta and 15% of Chlorophyta species observed in the water samples were classified as “very frequent”, as were 68% of Heterokontophyta and 33% of Chlorophyta species in the gut/stomach tract samples. Focusing at a species level, although in the water only Coelastrum sp. and Chroococcus sp. were observed in 100% and 75% of the samples, respectively, in the gastrointestinal tract the species Staurastrum sp., Aulacoseira sp., Scenedesmus sp. and Fragilaria crotonensis occurred in 80% to 100% of the samples. The present results showed that D. enno feeds not only on small chlorophytes microalgae, due to their convenient size that facilitates higher feeding rates, but also on large size diatoms, due to a possible nutritional advantage for the bivalves. Thus, a diet composed by large diatoms and small chlorophytes microalgae may be considered as the most reasonable for the maintenance of D. enno populations.

Resumo O conhecimento da composição da dieta do molusco de água doce Diplodon enno é de extrema importância para a sua cultura e propagação, permitindo desta forma a recuperação de populações em perigo de extinção no Brasil. As microalgas são a principal fonte de alimento para moluscos filtradores e os uniónidos sendo selecionadas por estes com base nas suas características celulares. O principal objectivo deste trabalho é analisar a composição fitoplanctônica da água e do conteúdo gastrointestinal do molusco D. enno, de forma a desenvolver uma dieta apropriada ao seu cultivo. Para isso, amostras de água e espécimes de bivalves foram recolhidos do rio São Francisco, cidade de Paulo Afonso, Bahia, Brasil. A composição de microalgas encontrada na água e no conteúdo do estômago/intestino foi muito diversa, sendo representada pelas seguintes divisões: Cyanophyta, Chlorophyta, Dinophyta e Heterokontophyta (diatomáceas). Atendendo à abundância relativa de cada divisão de microalgas, podemos afirmar que na água e no trato gastrointestinal Cyanophyta representa 15% e 14%, Chlorophyta 54% em ambos, Heterokontophyta 31% e 27% e Dinophyta 0% and 5%, respectivamente. De acordo com o critério CETESB de classificação de espécies de fitoplâncton, 50% das espécies de Cyanophyta e 15% das de Chlorophyta observadas nas amostras de água foram classificadas como “muito frequentes”, tal como aconteceu para 68% das espécies de Heterokontophyta e 33% das de Chlorophyta nas amostras do conteúdo do trato gastrointestinal. Realçando as espécies presentes, apesar de apenas Coelastrum sp. e Chroococcus sp. terem sido observadas em 100% e 75% das amostras de água, respectivamente, nas amostras de trato gastrointestinal Staurastrum sp., Aulacoseira sp., Scenedesmus sp. e Fragilaria crotonensis foram identificadas em entre 80% e 100% das amostras. Os resultados deste estudo mostram que D. enno se alimenta não apenas de pequenas microalgas clorófitas, devido ao seu pequeno tamanho que possibilita maiores taxas de filtração, como também de diatomáceas maiores, devido a uma possível vantagem nutricional para os bivalves. Assim sendo, uma dieta composta por diatomáceas e pequenas clorófitas poderá ser considerada a mais indicada para a manutenção de populações de D. enno.

Reproductive periods of Lucina pectinata (BIVALVE; LUCINIDAE) in the Paranaguá Estuarine Complex, Paraná - Brazil / Período reprodutivo de Lucina pectinata (BIVLAVE; LUCINIDAE) no Complexo Estuarino de Paranaguá, PR - Brasil

Abstract The objectives of the present study is to describe the size for exploitation and gonadal maturation of L. pectinata in Peças Island in Paraná coast. Twenty two individuals were sampled every month, from an intertidal flat of the Peças River, Municipality of Guaraqueçaba, during two periods – summer/autumn and winter of the 2009. Environmental parameter data was obtained at the same time of the biological sampling: temperature, salinity and seawater transparency at the Peças River mouth. The animals’ height, length, width, gross weight, wet weight of meat and dry weight of meat were measured at the lab. The gonad development stages (GDS), condition index (CI) and yield index (Y) were calculated. Sex identification was conducted by direct observation of the gonads and gametes under an optic microscope. Individuals were classified as males (M), females (F) or undetermined (U). The medium height observed was of 49.62 ± 6.84 mm. Period of more expressive gonad repletion were observed in summer when water temperature was higher. Results of GDS in both periods showed a predominance of partially filled gonad stages. This may be related with the fact that L. pectinata has intense gametogenesis activity, that is, the organisms do not have a resting interval, but go back to gonad restructuring rapidly after releasing the gametes. The continuity of the reproductive cycle of the specimens found in both studied periods could demonstrate a possible continuous reproduction of the species and a size for exploitation above 40.00 mm of height.

Resumo O presente estudo tem como objetivo descrever o tamanho de exploração e a maturação gonadal de L. pectinata na Ilha das Peças no litoral do Paraná. Vinte e dois indivíduos foram amostrados mensalmente na região entre-marés no Rio das Peças, Município de Guaraqueçaba, durante 2 períodos – verão/outono e inverno de 2009. Paralelamente às amostragens, foram obtidos dados dos parâmetros ambientais: temperatura, salinidade e transparência da água do mar na foz do Rio das Peças. A altura, comprimento, largura, peso bruto, peso úmido da carne e peso seco da carne dos animais foram medidos no laboratório. Foram calculados os estágios de desenvolvimento gonadal (EDG), índices de condição (IC) e de rendimento (R). A Identificação do sexo foi realizada por observação direta das gônadas e gametas sob microscópio óptico. Os indivíduos foram classificados como: machos (M), fêmeas (F) ou indeterminados (I). A altura média observada foi de 49,62 ± 6,84 mm. O período de maior repleção gonadal foi observado no verão, quando a temperatura da água foi mais elevada. Resultados dos EDG em ambos os períodos mostrou um predomínio de gônadas parcialmente cheias. Isso pode estar relacionado com o fato de que L. pectinata tem atividade gametogênese intensa, ou seja, os organismos não têm um intervalo de repouso, mas voltam a reestruturação das gônadas rapidamente após liberação dos gametas. A continuidade do ciclo reprodutivo dos espécimes encontrados em ambos os períodos estudados, pode demonstrar possível reprodução contínua da espécie e tamanho de exploração superior a 40,00 mm de altura.

Distribution and density of the mollusk Donax striatus (Linnaeus, 1767) in a tropical estuarine region in the brazilian semi-arid / Distribuição e densidade do molusco Donax striatus (Linnaeus, 1767) em região estuarina tropical do semiárido brasileiro

Abstract This study evaluated the spatial and temporal distribution and density of the bivalve Donax striatus, at beaches close to the Apodi/Mossoró River estuary, through, six semiannual sampling campaigns were performed between April/2009 and October/2011. The sampled area was delimited by 20 transects that were laid perpendicular to the beach line and extended over 300 m in the intertidal zone. Seven sampling points were established in each transect, organisms and sediment were collected, and water temperature and salinity were recorded. The highest D. striatus average density (103 individuals.m–2) was observed in April/2009 and the lowest (18 individuals.m–2) in October/2010. The highest D. striatus densities occurred in beaches further from the estuarine region as demonstrated by a significant positive correlation (r2 = 0.67 and p = 0.0007). The D. striatus densities presented significant negative correlations with the percentages of organic matter in the water. This species demonstrated an aggregated distribution in the studied area.

Resumo O objetivo da pesquisa foi verificar a distribuição (espacial e temporal) e a densidade do bivalve Donax striatus em praias próximas ao estuário do Rio Apodi/Mossoró, Rio Grande do Norte (RN), através de seis coletas semestrais (abril/2009 a outubro/2011). Foram dispostos 20 transectos perpendiculares à linha da praia, com 300 m de comprimento na zona intertidal. Em cada transecto foram estabelecidos sete pontos de amostragem e obtidas amostras de organismos e sedimento, foram determinadas a temperatura e salinidade da água. Com os resultados obtidos foi em abril/2009 a maior densidade média de D. striatus (103 indivíduos/m2) e em outubro/2010 a menor densidade (18 indivíduos/m2). As maiores densidades de D. striatus ocorreram em praias afastadas da região estuarina, com correlação significativa e positiva (r2=0,67 e p=0,0007). As densidades de D. striatus apresentaram correlações significativas e negativas com a matéria orgânica. Pôde-se constatar ainda que esta espécie apresentou uma distribuição agregada.

Bio-filtration capacity, oxygen consumption and ammonium excretion of Dosinia ponderosa and Chione gnidia (Veneroida: Veneridae) from areas impacted and non-impacted by shrimp aquaculture effluents / Bio-filtración, consumo de oxígeno y excreción amoniacal de Dosinia ponderosa y Chione gnidia (veneroida: veneridae), en áreas impactadas y no impactadas por efluentes de granjas camaroneras

Mollusks are some of the most important, abundant and diverse organisms inhabiting not only aquatic ecosystems, but also terrestrial environments. Recently, they have been used for bioremediation of aquaculture effluents; nevertheless, for that purpose it is necessary to analyze the capacity of a particular species. In this context, an experimental investigation was developed to evaluate the performance of two bivalves C. gnidia and D. ponderosa, collected from areas with or without shrimp aquaculture effluents. For this, the filtration capacity (as clearance rate) as well as the oxygen consumption and ammonia excretion rates were measured following standard methods. The clearance rate was significantly higher for D. ponderosa from impacted areas, when com- pared to C. gnidia, from both areas. Contrarily, the oxygen consumption was greater for C. gnidia from impacted areas compared to D. ponderosa from both areas. The same tendency was observed for the ammonia excretion with the highest rates observed for C. gnidia from impacted areas, whereas no differences were observed among D. ponderosa from both areas. The results suggest that both species developed different strategies to thrive and survive under the impacted conditions; D. ponderosa improved its filtration efficiency, while C. gnidia modified its oxygen consumption and ammonia excretion. We concluded that both species, and particularly D. ponderosa, can be used for bioremediation purposes.

Los moluscos son algunos de los organismos más importantes, abundantes y diversos que habitan no solo ecosistemas acuáticos sino también terrestres. Recientemente ellos han sido utilizados para la biorremediación de efluentes acuícolas; para este propósito, es necesario conocer la capacidad de especies particulares que funcionan como biorremediadores. En este contexto, se evaluó la eficiencia de filtración (medida como tasa de clarificación), así como las tasas de consumo de oxígeno y excreción amoniacal en los bivalvos D. pon- derosa y C. gnidia recolectados en áreas impactadas y no impactadas por efluentes de granjas camaroneras. La tasa de clarificación fue mayor para D. ponderosa procedente de áreas impactadas, comparada con la de C. fluctifraga en las dos áreas de recolecta. Contrariamente, la tasa de consumo de oxígeno fue superior en C. gnidia en las áreas impactadas al compararla con organismos de áreas no impactadas y con D. ponderosa de las dos áreas de recolecta. La tasa de excreción amoniacal siguió una tendencia similar con valores más altos para C. gnidia en áreas impactadas, mientras que no se observaron diferencias para D. ponderosa entre las áreas de recolecta. Los resultados sugieren que ambas especies desarrollan diferentes estrategias para adaptarse y sobrevivir bajo condiciones de impacto; D. ponderosa mejora su eficiencia de filtración y C. gnidia modifica su consumo de oxígeno y excreción amoniacal. Se concluye que ambas especies, pero sobre todo D. ponderosa pueden ser utilizadas con propósitos de biorremediación.

Intra-specific variability in life-history traits of Anadara tuberculosa (Mollusca: Bivalvia) in the mangrove ecosystem of the Southern coast of Ecuador / Variaciones en la historia de vida de Anadara tuberculosa (Mollusca: Bivalvia) en el ecosistema de manglar de la costa Sur de Ecuador

Anadara tuberculosa is one of the most important bivalves along the Western Pacific coast because of its commercial value. Nevertheless, the variability in growth, longlife span, natural mortality and reproductive parameters of this mangrove cockle has not yet been described. The aim of this study was to analyze these lifehistory traits in three areas of the Southern coast of Ecuador. Empirical and length-based methods were used to estimate these biological parameters. Body size data were collected from the commercial fishery between 2004 and 2011 in landing ports near to the Archipelago of Jambeli [Puerto Bolivar (PB), Puerto Jeli (PJ) and Puerto Hualtaco (PH)]. The von Bertalanffy growth parameters for combined sex were estimated between 70.87 to 93.45mm for L∞ and 0.22 to 0.80/year for k. The growth indices (Φ’) ranged from 3.17 to 3.85, while the overall growth performance (OGP) ranged from 5.03 to 5.82. The mean of long-life span (t max), size and age at maturity (L50% and t50%) were estimated in 7.71±2.53years, 39.13±2.24mm and 1.46±0.56years for PB; 9.51±2.85years, 37.78±1.95mm and 1.37±0.41years for PJ and 5.81±2.11years, 39.73±3.31mm and 0.94±0.41years for PH. Natural mortality (M) ranged from 0.46 to 1.28/year. We concluded that significant intra-specific variation was observed in a temporal scale in Φ’ and OGP indices as well as L50% and M. Therefore, temporal changes in these life-history traits should be taken into account when assessing the status of the mangrove cockle fishery.

La pesquería de la concha prieta (Anadara tuberculosa) es una de las más importantes a lo largo de la costa del Pacifico. Las variaciones intra-especificas en el crecimiento, longevidad, mortalidad natural y parámetros reproductivos de la concha prieta, aún no han sido descritas. Por lo tanto, el objetivo de este estudio fue analizar esos parámetros biológicos en tres áreas al Sur de Ecuador. Métodos empíricos y basados en tallas fueron empleados para estimar los parámetros de historia de vida. Los datos de tallas analizados correspondieron al periodo 2004-2011 y son provenientes del muestreo de los desembarques de los puertos adyacentes al Archipiélago de Jambeli [Puerto Bolivar (PB), Puerto Jeli (PJ) y Puerto Hualtaco (PH)], al Sur de Ecuador. Los parámetros de crecimiento oscilaron entre 70.87 y 93.45mm de L∞ y 0.22 a 0.80/año de k. Mientras que los índices de crecimiento entre 3.17 a 3.85 de Φ’ y 5.03 a 5.82 de OGP. Los valores promedio de longevidad (t max), talla y edad de madurez (L50% y t50%) fueron de 7.71±2.53años, 39.13±2.24mm y 1.46±0.56años en PB; 9.51±2.85años, 37.78±1.95mm y 1.37±0.41años en PJ y de 5.81±2.11años, 39.73±3.31mm y 0.94±0.41años en PH. Las estimaciones de mortalidad natural (M) oscilaron entre 0.46 y 1.28/año. Importantes cambios intra -especificos se observaron a escala temporal tanto en los índices Φ’ y OGP, así como en L50% y M. Por lo tanto, se sugiere considerar las variaciones temporales en los parámetros biológicos de A. tuberculosa, al momento de caracterizar el estatus de su pesquería y más aun si es sometida a altos niveles de extracción.

Population structure of the bivalve Anomalocardia brasiliana, (Gmelin, 1791) in the semi-arid estuarine region of northeastern Brazil / Estrutura populacional do bivalve Anomalocardia brasiliana, (Gmelin, 1791) em região estuarina do semi-árido do nordeste brasileiro

For several decades, the bivalve mollusk Anomalocardia brasiliana has been extracted in estuarine areas in the semi-arid region of northeastern Brazil. However, information on both dynamics and abundance of their populations are missing. In this context, the present study, therefore, investigated several aspects of the population structure of A. brasiliana on beaches near the estuary of the Apodi River in Northeast Brazil. The aims were to determine the population density of A. brasiliana during different times of the year, to estimate population parameters, and to relate species density and distribution to the abiotic characteristics of the region. Sampling was performed from March/2007 and May/2008, we collected samples of sediments and mollusks along 180 m transects in the intertidal area on the beaches Barra and Pernambuquinho, Grossos - RN. At each sampling site, samples of sediments and mollusks were collected in the intertidal area along 180 m transects. The highest and lowest average densities on Pernambuquinho beach were 1148 (April/2007), and 100 individuals.m2 (May/ 2008), respectively. On Barra beach, the highest and lowest densities were 1813 (April/2007) and 951 individuals.m2, (November/2007), respectively. The densities of A. brasiliana on both beaches were significantly different only in the months of January, April and May/ 2008. Length of the individuals ranged from 1 to 28 mm, with most individuals measuring between 22 and 24 mm. Length growth rate parameters for A. brasiliana were L = 28.68 mm and k = 0.61 year1 on Barra beach, and L = 29.87 mm and k = 0.48 year1 on Pernambuquinho beach. The growth rate curves for A. brasiliana suggest the presence of three well defined cohorts, thus pointing to a continuous reproduction cycle with peak recruitment between October/2007 and March/2008. A. brasiliana density decreased predominantly during the heavy rains of 2008, probably due to an accumulation of sediments and decreasing salinity. This disturbance probably affected population of this species in the region.

O molusco bivalve Anomalocardia brasiliana há décadas vem sendo coletado em região estuarina do semi-árido do nordeste Brasileiro. No entanto, são escassas as informações sobre a dinâmica e abundância de suas populações na região. Neste contexto, o presente trabalho objetivou estudar aspectos da estrutura populacional de A. brasiliana em praias localizadas próximas à região de estuário do rio Apodi/Mossoró - RN no intuito de verificar a densidade populacional de A. brasiliana durante as diferentes épocas do ano; estimar os parâmetros populacionais e relacionar as características abióticas de região com a distribuição e densidade desta espécie. As coletas foram realizadas no período de março/2007 a maio/2008 nas praias de Barra e Pernambuquinho no município de Grossos - RN. Em cada ponto foram realizados transcectos de 180 metros na região de entremarés e coletadas amostras de sedimento e de moluscos. O maior valor médio de densidade na praia de Pernambuquinho foi de 1148 indivíduos/m2, no mês de abril/07 e o menor foi em maio/08 (100 indivíduos/m2). Na praia de Barra o maior valor foi de 1813 indivíduos/m2, no mês de abril/08 e o menor foi em novembro/07 com 951 indivíduos/m2. Os comprimentos variaram de 1 a 28 mm, sendo mais frequentes indivíduos com comprimentos entre 22 a 24 mm. Foram constatadas diferenças significativas entre as densidades de A. brasiliana em ambas as praias, apenas nos meses de janeiro, abril e maio de 2008. Os parâmetros que descrevem o crescimento em comprimento de A. brasiliana na praia de Barra foram: L = 28,68 mm e k = 0,61 ano1, enquanto que para a praia de Pernambuquinho foram: L = 29,87 mm e k = 0,48 ano1. As curvas de crescimento de A. brasiliana sugerem a presença de três coortes bem definidas, indicando uma reprodução contínua com picos de recrutamento ocorrerendo entre os meses de outubro/07 a março/08. Pode-se verificar uma diminuição da densidade de A. brasiliana, especialmente no período de chuvas intensas do ano de 2008, o que provavelmente esteve associado ao aporte de sedimentos e a diminuição da salinidade. Esta perturbação provavelmente afetou as populações desta espécie na região.

Biología Reproductiva de Mytilopsis leucophaeata (Conrad, 1831) (Bivalvia: Dreissenidae) de la Laguna de Tampamachoco, Túxpam-Veracruz / Reproductive Biology of Mytilopsis leucophaeata (Conrad, 1831) (Bivalvia: Dreissenidae) of Tampamachoco Lagoon, Tuxpan-Veracruz

Se caracterizó el ciclo reproductivo de Mytilopsis leucophaeata (Conrad, 1831) en organismos colectados mensualmente durante un ciclo anual en la laguna de Tampamachoco, Túxpam, Veracruz, que se ubica en la costa del Golfo de México en la Región Terrestre Prioritaria (RTP-103) de CONABIO considerada sitio RAMSAR 1602 en México. Los resultados histológicos indican que M. leucophaeata presenta cuatro etapas gametogénicas: gametogénesis, madurez, desove total para hembras y expulsión parcial para machos. Uno de los principales factores que influyen en el desove sincrónico de gametos tanto en machos como en hembras es la salinidad, en los meses de enero a marzo.

The reproductive cycle of Mytilopsis leucophaeata (Conrad, 1831) was characterized in organisms collected monthly during an annual cycle in Tampamachoco lagoon Tuxpam-Veracruz, located on the coast of the Gulf of Mexico in the Terrestre Prioritaria Region (RTP-103) of CONABIO considered a RAMSAR 1602 site in Mexico. Histological results indicated that M. leucophaeata has four gametogenic stages: gamete, maturity, female's total spawning and partial expulsion inmales. One of the main factors that influence the synchronous spawning gametes in both males and females is salinity, in the months of January to March.

The reproductive biology of Lutraria philippinarum (Veneroida: Mactridae) and its fishery in the Philippines

The Snout Otter Clam, Lutraria philippinarum is a regularly harvested bivalve species for food and also as a source of income in the Philippines. For sustainable supply of this resource in the wild, efficient and effective management strategies are needed, and the evaluation of its reproductive biology and fishery are required. In this study, the reproductive biology and fishery of L. philippinarum in the Philippines were examined monthly from January to December 2010 in North Bais Bay, Manjuyod, Negros Oriental and Philippines. For reproductive biology, otter clams were sampled, and sex ratio (by microscopic observation), size at sexual maturity, shell length (with a vernier caliper), gonad development (by histological examination as resting, developing, mature, spawning and spent) and spawning season were determined. Other information such as water temperature, salinity, pH and dissolved oxygen were also measured. To obtain information on the L. philippinarum fishery, interviews were conducted in Negros Oriental, Bohol, Cebu and Sarangani. A total of 677 snout otter clams were sampled. The study showed that L. philippinarum sex ratio was 1:1.15 and showed no significant difference from 1:1 ratio. Males attained its first sexual maturity at 43mm shell length while the females at 46mm. Histological examination on gonad development indicated that gametogenesis, maturation and spawning season of L. philippinarum occurred throughout the year with two spawning peaks, January and June. Changes in water temperature in North Bais Bay may have influenced the spawning peaks of L. philippinarum. Data on the fishery of L. philippinarum revealed that the Catch Per Unit Effort of L. philippinarum in the Philippines ranged from 0.2kg/hr-man to 1.25kg/hr-man suggesting low shell catch. We recommend that some mature individuals have to be left in the population to allow in situ breeding.

Lutraria philippinarum es una especie de bivalvo recolectada regularmente para la alimentación y como fuente de ingreso en las Filipinas. Para el suministro sostenible de este recurso en la naturaleza, se necesitan estrategias de manejo efectivas, así como la evaluación de su biología reproductiva y pesquera. Se examinaron estos aspectos mensualmente de enero-diciembre 2010 en North Bais Bay, Manjuyod, Negros Oriental, Filipinas. Se tomó medida del tamaño a la madurez sexual, proporción de sexos (con observación microscópica), longitud de la concha (con calibrador vernier), desarrollo de gónadas (con examinación histológica del descanso, desarrollo, madurez, desove y gasto) y época de desove. Para obtener información de la pesquería de L. philippinarum, se realizaron entrevistas en Negros Oriental, Bohol, Cebu y Sarangani. Un total de 677 ostras fueron muestreadas. Se encontró que la proporción de sexos fue 1:1.15 y no se observó diferencia significativa de la proporción 1:1. Los machos alcanzaron la madurez sexual a la longitud de concha de 43mm mientras que las hembras a 46mm. El análisis histológico del desarrollo de las gónodas indicó que la gametogénesis, maduración y desove ocurren durante todo el año con dos picos de desove, enero y junio. Los datos sobre la pesquería revelaron que la captura por unidad de esfuerzo de L. philippinarum osciló entre 0.2kg/h hombre a 1.25kg/h hombre que sugieren baja captura de conchas. Recomendamos que algunos individuos maduros tienen que ser dejados en la población para permitir la reproducción in situ.

Reproductive cycle of Anomalocardia brasiliana (Mollusca: Bivalvia: Veneridae) in the estuary of the Cachoeira River, Ilhéus, Bahia / Ciclo reprodutivo de Anomalocardia brasiliana (Mollusca: Bivalvia: Veneridae) no estuário do Rio Cachoeira, Ilhéus, Bahia

The aim of this study was to characterize the reproductive cycle of Anomalocardia brasiliana, typical of the estuarine region of the Cachoeira River, Ilhéus, Bahia, Brazil. For this purpose, 20 specimens were collected biweekly between August 2005 and August 2006 on an intertidal bank (14º 48' 23" S and 39º 02' 47" W). The animals were measured on the anteroposterior axis (length), examined macroscopically and removed from the shell and fixed in Davidson's solution. Subsequently, the tissues were impregnated in paraffin, cut into 7 mm sections and stained with Harris hematoxylin and eosin (HE). The slides were examined under a light microscope. The water temperature at the site ranged from 24 to 30.5 ºC (mean: 27.4 ºC; SD ± 1.9), salinity from zero to 23 (mean: 13.7; SD ± 7.5) and rainfall from 28.3 mm to 248.8 mm monthly (yearly mean: 130 mm). The sample (n = 478) showed a sex ratio (M: F) of 1: 1.2 (p < 0.05) and no cases of hermaphroditism. There was no sexual dimorphism. Males and females showed reproductive synchrony. The reproductive cycle was continuous, with releases of gametes mainly in spring, summer and autumn. These results are similar to those found in other regions, but there was no reproductive rest period as reported for populations in higher latitudes.

Neste estudo objetivou-se caracterizar o ciclo reprodutivo de Anomalocardia brasiliana da região estuarina do rio Cachoeira, Ilhéus, Bahia, Brasil. Para tal, 20 espécimes foram coletados quinzenalmente, entre agosto de 2005 e agosto de 2006, em um banco entremarés da região (14º 48' 23" S e 39º 02' 47" W). Os animais foram medidos quanto ao seu eixo ântero-posterior (comprimento), analisados macroscopicamente, retirados da concha e fixados em solução de Davidson. O processamento posterior dos tecidos incluiu impregnação em parafina, obtenção de cortes com 7 mm de espessura e coloração com Hematoxilina de Harris e Eosina (HE). As lâminas foram examinadas em microscopia de luz. A temperatura da água do local variou de 24 a 30,5 ºC (média: 27,4 ºC; DP ± 1,9), a salinidade de zero a 23 (média: 13,7; DP ± 7,5) e a precipitação pluviométrica mensal de 28,3 mm a 248,8 mm (valor médio anual: 130 mm). A população analisada (n = 478) apresentou proporção sexual (M: F) de 1: 1,2 (p < 0,05) e nenhum caso de hermafroditismo. Não houve dimorfismo sexual. Machos e fêmeas apresentaram sincronismo reprodutivo e o ciclo de reprodução foi contínuo, com pequenos picos de liberação de gametas principalmente na primavera, no verão e no outono. Esses resultados foram similares aos encontrados em outras regiões, porém não houve um período de repouso sexual propriamente dito, como está relatado em populações de latitudes mais altas.

Effects of human trampling on a rocky shore fauna on the Sao Paulo coast, southeastern Brazil / Impactos do pisoteio humano na fauna de um costão rochoso do litoral de São Paulo, no sudeste brasileiro

Increased tourist activity in coastal regions demands management strategies to reduce impacts on rocky shores. The highly populated coastal areas in southeastern Brazil are an example of degradation caused by development of industry and tourism. Among different shore impacts, trampling has been intensively studied, and may represent a significant source of stress for intertidal fauna. A randomised blocks design was applied to experimentally study the effects of two different trampling intensities on richness, diversity, density and biomass of the rocky shore fauna of Obuseiro beach, Guarujá, southeastern Brazil. Blocks were distributed in two portions of the intertidal zone, dominated respectively by Chthamalus bisinuatus (Cirripedia) and Isognomon bicolor (Bivalvia). Blocks were trampled over three months, simulating the vacation period in Brazil and were monitored for the following nine months. Results indicate that Chthamalus bisinuatus is vulnerable to trampling impacts. Richness, diversity and turn-over index tended to be higher in trampled plots four months after trampling ceased. In general, results agree with previous trampling studies, suggesting that even low intensities of trampling may cause some impact on intertidal communities. Management strategies should include isolation of sensitive areas, construction of boardwalks, visitor education and monitoring programmes. In Brazil, additional data obtained from experimental studies are necessary in order to achieve a better understanding of trampling impacts on rocky shore communities.

O aumento da atividade turística em áreas costeiras nas últimas décadas faz necessária a adoção de estratégias de manejo para reduzir os impactos gerados às comunidades de costões rochosos. A região costeira do sudeste brasileiro possui bons exemplos de degradação causada pelo turismo e desenvolvimento industrial. Dentre os diferentes distúrbios causados pela visitação, o pisoteio têm sido estudado de forma intensa e pode representar uma fonte significativa de impactos para as comunidades da zona entre-marés. Neste projeto, foi aplicado um desenho de blocos randômicos para se avaliar experimentalmente os efeitos de duas intensidades de pisoteio na riqueza, diversidade, densidade, recobrimento e biomassa da fauna de um costão situado na praia do Obuseiro, no município do Guarujá, São Paulo, Brasil. Os blocos foram alocados em dois povoamentos diferentes, dominados respectivamente por Chthamalus bisinuatus (Cirripedia) e Isognomon bicolor (Bivalvia). O pisoteio foi aplicado durante três meses, simulando a temporada de férias no Brasil, e os blocos foram monitorados nos nove meses seguintes. Os resultados indicaram que Chthamalus bisinuatus é vulnerável aos impactos do pisoteio. Os índices de riqueza, diversidade e turnover apresentaram uma tendência ao aumento nas áreas pisoteadas quatro meses após o término do pisoteio. No geral, os resultados concordam com estudos anteriores e sugerem que mesmo baixas intensidades do distúrbio podem causar impacto às comunidades bentônicas. Estratégias de manejo devem envolver o isolamento de áreas sensíveis, a construção de passarelas, a educação dos visitantes e o monitoramento das comunidades impactadas. No Brasil, a realização de maior quantidade de estudos experimentais é necessária para a melhor compreensão dos impactos do pisoteio nas comunidades de costões rochosos.

Vertical distribution, segregation by size and recruitment of the yellow clam Mesodesma mactroides Deshayes, 1854 (Mollusca, Bivalvia, Mesodesmatidae) in exposed sandy beaches of the Rio Grande do Sul state, Brazil / Distribuição vertical, segregação por tamanho e recrutamento do marisco branco Mesodesma mactroides Deshayes, 1854 (Mollusca, Bivalvia, Mesodesmatidae) em praia arenosa exposta do Rio Grande do Sul, Brasil

The vertical distribution and the segregation by size of the yellow clam Mesodesma mactroides Deshayes, 1854 were investigated in the intertidal zone and its limits with the lower and upper shores at exposed sandy beaches of Rio Grande do Sul state, Brazil. The gathering was made throughout 12 months; from the Pinhal beach towards the south of the State, in six 15 km equidistant transects, determined through random selection. In these transects, the calculation of 30 consecutive waves was made in order to determine its average amplitude point (P0), from which two points were marked towards the lower shore (P-1 and P-2) and three towards the upper shore (P1, P2 and P3). A 30 by 50 cm cylinder was buried down to the depth of 40 cm, the material was separated with a 0.25 cm mesh and the specimens were quantified and measured in length. The yellow clam presented segregation by size, especially between recruit and adult individuals, with recruits occupying preferably the zones above P0 and adults from this point towards the sea. The young specimens are distributed through all zones, mixed with adult and recruit specimens, which dismisses the hypothesis of segregation by size in function of competition for space and food, once the burying depth is directly proportional to their length. However, the segregation between recruits and adults might be related to the filtering mechanism of the adults, which could ingest the larva, as well as the fact that the recruits, being small and light, are easily transported to the regions above P0. Seasonal migration was observed for adult individuals during winter and spring, probably associated to the reproduction period of the species, being that the peak of recruitment was greater in the end of the winter and the beginning of spring.

Foram investigadas a distribuição vertical e a segregação por tamanho no marisco branco Mesodesma mactroides Deshayes, 1854 na zona intermareal e seu limite com o infra e o supralitoral nas praias arenosas expostas do Rio Grande do Sul, Brasil. Ao longo de 12 meses, foram realizadas as coletas a partir da praia de Pinhal em direção ao sul do Estado, em seis transectos eqüidistantes 15 km, determinados mediante sorteio. Nestes, procedeu-se ao cálculo de 30 ondas consecutivas para avaliar o seu ponto médio de amplitude (P0), a partir do qual, foram assinalados dois pontos em direção ao infralitoral (P-1 e P-2) e três em direção ao supralitoral (P1, P2 e P3). Enterrou-se um cilindro de 30 x 50 cm até 40 cm de profundidade, sendo o material triado em malha de 0,25 cm com os exemplares quantificados e mensurados em comprimento. O marisco branco apresentou segregação por tamanho, em especial entre os indivíduos recrutas e os adultos, com os recrutas ocupando preferencialmente as zonas acima de P0 e os adultos, deste ponto em direção ao mar. Já os jovens estão distribuídos por todas as zonas, mesclados com os espécimes adultos e com os recrutas, o que descarta a hipótese de segregação por tamanho em função da competição por espaço e por alimento, uma vez que a profundidade em que se enterram é diretamente proporcional ao seu comprimento. Já a segregação entre os indivíduos recrutas e adultos, pode estar relacionada ao mecanismo de filtração dos adultos, que poderiam ingerir as larvas, como também, ao fato de que os recrutas, por serem pequenos e leves, são facilmente transportados para as regiões acima de P0. Foi constatada a migração sazonal por parte dos indivíduos adultos no inverno e na primavera, provavelmente associada, ao período de reprodução da espécie, pois o pico de recrutamento mais pronunciado foi no fim do inverno e no início da primavera.

Ciclo reproductivo del molusco Atrina maura (Pterioidea: Pinnidae) en un sistema lagunar costero, al sur del Pacífico tropical mexicano

Reproductive cycle of the mollusk Atrina maura (Pterioidea: Pinnidae) in a coastal lagoon system of the Mexican South Pacific. From February 1997 to February 1998, random samples of the mollusk Atrina maura were collected on a monthly basis from the Corralero-Alotengo lagoon system, Oaxaca, Mexico. The soft parts were separated from the valve, washed in situ, and placed in a Davison solution. The gonadosomatic index (GSI) and the muscle yield index (MYI) were measured, and the reproductive cycle was characterized by histological cuts. A. maura has two important reproductive periods, one from April to July and another from October to November; there is a resting period from August to September. The reproductive cycle has a direct relationship with the GSI and a reverse relationship with the MYI. There was evidence of a close relationship of the spawning and post-spawning periods with the water temperature (R = 0.991, p = 0.002). Females dominate numerically throughout the year, but the difference is significant (X²: p= 0.05) only in November. Rev. Biol. Trop. 55 (3-4): 839-852. Epub 2007 December, 28.

De febrero de 1997 a febrero de 1998, se recolectaron mensualmente muestras aleatorias del molusco Atrina maura en el sistema lagunar Corralero-Alotengo, Oaxaca, México. Se extrajeron las partes blandas para lavarlas in situ y fijarlas en solución Davison. En el laboratorio se pesaron para obtener los índices gonadosomático (IGS) y de rendimiento muscular (IRM), y mediante cortes histológico de las gónadas se caracterizó el ciclo reproductivo. Esta población se reproduce casi todo el año, con dos periodos reproductivos importantes: uno de abril a julio y otro de octubre a noviembre, y una sola época de reposo, en agosto y septiembre. El ciclo reproductivo tiene una relación directa con el IGS e inversa con el IRM. Hay evidencias de una relación estrecha de las época de desove y postdesove con la temperatura del agua (R = 0.991, p 0.002). Las hembras predominaron casi todo el año, aunque esta proporción solo tuvo diferencias estadísticamente significativas en noviembre (X²: p= 0.05).

Efecto de la alimentación sobre la condición fisiológica del mejillón Perna viridis (Bivalvia: Mytilidae), según el cociente ARN/ADN / Food effect on the physiological condition of the Perna viridis mussel (Bivalvia: Mytilidae), using the RNA/DNA quotient

The green mussel, Perna viridis, became widespread in the northern coast of Sucre State since its arrival to Venezuela in 1993. RNA/DNA and Protein/DNA ratios were used to study the effect of starvation on its instantaneous growth. The mussels were collected in La Esmeralda and Chacopata, acclimatized in the laboratory for four weeks and maintained for another six weeks in two groups: one fed ad libitum and another without food (this later group was later fed for two additional weeks). Protein (colorimetric method), and nucleic acid concentrations (RNA and DNA, fluorometric method with ethidium bromide) were measured in adductor muscle, digestive gland and gills. The instantaneous growth was assessed using RNA/DNA and Protein/DNA rations. These indexes were always higher in the fed organisms. Animals from Chacopata were in better physiological condition that those from La Esmeralda during the abstinence time (six weeks). Muscle was the best tissue to determine instantaneous growth. The RNA/DNA ratio is a reliable index to determine the physiological condition and instantaneous growth of this species.

Efecto de la temperatura de aclimatación sobre el crecimiento instantáneo de Perna viridis (Bivalvia: Mytilidae), según el cociente ARN/ADN / Effects of acclimation temperature on the instant growth of Perna viridis (Bivalvia: Mytilidae), using the RNA/DNA quotation

Temperature affects growth rate in aquatic organisms. This can be evaluated in short term using biochemical indexes (RNA/DNA and Protein/DNA). The effect of acclimatization temperature on the instantaneous growth and physiological condition of Perna viridis was studied in organisms collected in La Esmeralda, Sucre State (Venezuela) and taken to the laboratory, where groups of 100 organisms (size 3.0 - 3.5 cm, anteroposterior measurement) were acclimatized at 15, 20, 26 or 28 degrees C during four weeks. Later they were kept in a 60 liters aquarium for another six weeks under the same conditions. Each week, ten organisms per group were extracted to measure concentrations of RNA, DNA (by a fluorometric method with ethidium bromide) and proteins (by a colorimetric method), in tissues (digestive gland, adductor muscle and gills). Protein concentration was greater and highly significant at 15 degrees C for all studied tissues. The opposite was obtained with the RNA/DNA and Protein/DNA ratios: the greatest increase was observed at the highest temperature (28 degrees C) for all tissues. At the lowest temperature there was a tendency to reduce both indexes with time. Greater instantaneous growth can be expected at higher temperatures and 28 degrees C was optimal for growth in these specimens.

Producción somática de dos especies de Crassostrea virginica e Ischadium recurvum (Bivalvia) en Mecoacán, Tabasco, México / Somatic production of two species: Crassostrea virginica and Ischadium recurvum Bivalvia in Mecoacán, Tabasco, México

The Mexican oyster fishery, 90% supported by the coastal lagoons of the Gulf of Mexico, has decreased drastically in the last six years as a result of anthropogenic pollution and improper management. The mussel Ischadium recurvum has proliferated and competes with oysters for space and probably food. Crassostrea virginica and Ischadium recurvum were studied to evaluate somatic production with biometry and physiological condition indices (PCI's) during an annual cycle. A random sample of 200 organisms was taken montly for each species. Condition indices wet flesh weigth: wet shell weight ratio (WFW/WSW), dry flesh weight: wet flesh weight ratio (DFW/WFW), dry flesh wet: dry shell weight ratio (DFW/DSW), and ash free dry weight: tissue dry weight (AFDW/TDW) were calculated. In order to stablish physiological condition and temporal variability, these indices were compared between species and months. The somatic production of mussels was higher than in oysters. This enhancement in production could be explained by: 1) Mussel uses less energy for shell production, 2) a constant recruitment of mussel almost year-round, and 3) the mesohalin lagoon was more favourable to the mussel.

An electronic device to record behavioural activity of bivalves.

An electronic device to record the valvular movements of clams was fabricated using a Hall effect transducer. It was used to record the responses of Anadara granosa, an arcid clam harvested from coastal waters of Bombay, to a chemical toxicant (10 ppm CuSO4) after 96 hr exposure to naphthalene (5, 10 and 15 ppm). The clams exposed to naphthalene did not respond to the presence of a chemical toxicant (10 ppm CuSO4) while the control clams responded and closed their shells rapidly.