The population biology and production of the stout razor clam Tagelus plebeius Lightfoot, 1786 were investigated on an intertidal sandflat on the southeast coast of Brazil (Enseada Beach, São Sebastião, state of São Paulo) between April 1997 and April 1998. Two rectangular sites of 50 X 10 m parallel to the waterline were established, site A (upper intertidal level) and site B (middle intertidal level), where the samples were taken in an 0.5 x 0.5 m quadrat. High abundances were recorded in winter and spring, with no significant differences between the sites. The high bivalve abundances were related to the presence of very fine homogeneous sediment with low salinities. Tagelus plebeius had negative allometric growth, characteristic of deep burrowers for the relationships DM/SL and AFDM/SL. Parameters of the modified von Bertalanffy growth function were: L∞ = 67.01 mm, K = 1.73 year-1, t0 = -0.11 year, C = 0.43, WP = 0.96. The instantaneous mortality (Z) was 3.12 year-1, relatively high in comparison to other tropical bivalve populations. Secondary production was 1.53 g AFDM m-2 year-1, with a P/B ratio reaching 1.37 year-1. This high turnover ratio (P/B) was related to a rapid population replacement, connected with the short life span and high mortality of the species

This study describes the gametogenic cycle of Ophioderma januarii Lütken, 1856, a common species of ophiuroid in Southeastern Brazil. The specimens were collected during the project "Biodiversidade Bêntica Marinha no Estado de São Paulo-BIOTA/FAPESP-Bentos Marinho" (Marine benthic biodiversity in the State of São Paulo-BIOTA/ Fapesp-Marine Benthos) which was conducted off the northern coast of the state of São Paulo. Specimens were captured monthly between February 2001 and December 2002. Due to the low number of individuals the monthly data was grouped in seasons (spring to winter). A total of 101 specimens were obtained: 33 in spring, 10 in summer, 23 in autumn, and 35 in winter. The gonads of eighty-eight individuals (45 females, 42 males, and one hermaphrodite) were analyzed histologically. The male and female gametogenic cycles were classified into five different gonadal stages, which were analyzed separately. The reproductive pattern could be defined through histological analyses of male and female gonads, together with oocyte diameter frequency. Some general conclusions could also be reached: this is a gonochoric species that reproduces year-round but increases its gonadal activity during summer; based on the size of its mature oocytes, it has lecithotrophic development. Apparently, its recruitment is enhanced in late summer, and smaller individuals are more frequent during autumn and winter

The ophiuroid Ophionereis reticulata (Say, 1825) occurs in the sediment-rocky shore interface, under small stones. Its diet is analyzed in this short communication. Specimens were collected at the Praia Grande beach, located on the northern coast of the state of São Paulo, Brazil, in July, 2002 and January, 2003. The animals were fixed in 70% ethanol and dissected to obtain their stomach contents. Of the total (35), 77.1% (27) had ingested some kind of food and, among those, 81.4% (22) had more than one item. The mean number of food items per stomach was 1.9. Ophionereis reticulata is an omnivorous species, consuming sediment, green and red algae, and polychaetes.
O ofiuróide Ophionereis reticulata (Say, 1825) ocorre na interface sedimento rocha de costões rochosos, sob pequenas pedras. Alguns aspectos de sua dieta alimentar foram analisados nesta nota. A amostragem foi realizada na Praia Grande, localizada no litoral norte do estado de São Paulo, Brasil. Os indivíduos, coletados em julho de 2002 e janeiro de 2003, foram fixados em álcool 70% e dissecados para obtenção de seus conteúdos estomacais. Do total (35), 77,1% (27) tinham ingerido algum tipo de alimento, e destes, 81,4% (22) possuíam mais de um item. O número médio de itens alimentares por estômago foi 1,9. Ophionereis reticulata é uma espécie onívora, consumindo sedimento, algas verdes e vermelhas, e poliquetas

Knowledge of the population dynamics and productivity of exploited species is essential to achieve the sustainable development of fisheries, and to ensure sustainable, long-term use of these resources. The venerid clam Anomalocardia brasiliana is harvested as a fishery resource from the French West Indies to Brazil. Yet, the exploitation of this species is not backed by management or regulations based on scientific knowledge. This can result in reduced (or even depleted) A. brasiliana density and biomass. Here, we examined the population dynamics of A. brasiliana over the course of 1 year at Cidade Beach, a sheltered sandy beach located in south-eastern Brazil. Sampling was done monthly from March 2007 to February 2008. The sampled population was predominantly juvenile. Growth and recruitment were continuous, indicating no major fluctuation in limiting factors, such as temperature, salinity and food. Nevertheless, the abundance and the turnover rate (P/B ratio) of A. brasiliana at Cidade were much smaller than the values observed in other areas of occurrence. The mortality was more intense in young individuals, and the peak of individual production occurred in individuals with a 25 mm shell length, suggesting that individuals smaller than this size should not be exploited.

Tagelus plebeius (Lightfoot, 1786) is a stout razor clam that is economically exploited in several countries, including several local fisheries along the Brazilian coast. Despite its wide distribution and economic importance, there are few studies that have examined the population biology of this species. This study aimed to improve the current knowledge about the biology of T. plebeius by investigating its growth and mortality on a subtropical sandy beach in Southeast Brazil over a 1-year period. In addition, the reproduction of T. plebeius was analyzed through qualitative and quantitative histological analyses during the last 7 months of the study. The parameters of the von Bertalanffy growth function were estimated to be L ? = 74.14 mm, K = 0.52 year -1 , C = 0.47, and WP = 0.94. The instantaneous mortality rate (Z) was 2.16 year -1 , and the life span was 2.58 years. We confirmed variations (H = 651.35; P \ 0.05) in the shell length over the months of the study, and the recruitment was higher-but still low-in summer. Four cohorts were observed in the distribution of shell length frequencies. The sex ratio of the population was 1:1 during the study period, and a synchronism in gonadal development and spawning was found between males and females. The high mortality (Z) and low recruitment rates can be interpreted as reflecting that the population of T. plebeius is under a low restoration process and could be an indication that this species has an endangered status in the study area.

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