Entre abril/2000 a abril/2001 todos os indivíduos de C. danae Smith, 1869 procedentes de um mesmo arrasto foram coletados em visitas quinzenais às bancas dos pescadores do Balneário Shangri-lá (25°37'30"S, 48°25'08"W) visando investigar sua estrutura populacional e parâmetros reprodutivos. De cada indivíduo foi determinado o sexo, a largura cefalotorácica (LC) e o peso úmido (P). O estágio de maturação gonadal foi determinado macroscopicamente pelo aspecto e coloração das gônadas. A massa de ovos das fêmeas foi separada para análise da fecundidade. Foi observado um predomínio de fêmeas adultas (incluindo as ovígeras) em relação às outras categorias. A proporção sexual foi 0,9:1 (machos:fêmeas). O tamanho de primeira maturação sexual foi estimado em 60,5 mm (machos) e 52,7 mm (fêmeas). A relação LC/P foi isométrica para machos e fêmeas. A largura da carapaça das fêmeas ovígeras variou de 43,2 a 79,5 mm (67 ± 8 mm), com fecundidade variando entre 25.127 e 246.676 ovos, com uma média de 127.177 ovos por fêmea. O diâmetro médio dos ovos foi de 0,22 mm. A maior incidência de fêmeas ovígeras ocorreu durante o inverno e o verão.

ABSTRACT

In the Central South Brazil Bight, a multispecific demersal trawl fishery is conducted by trawlers licensed for the industrial pink shrimp (Penaeus paulensis and Penaeus brasiliensis) fishery. In addition to the pink shrimp, many by‐catch species have become increasingly valued in the last two decades. In spite of the importance of this multispecific fishery, the oceanographic characteristics of the inner continental shelf, onshore the 100 m isobath, are poorly known. In this paper we present, for the fist time, monthly oceanographic records taken from December 1995 to May 1997 with the R/V ‘Diadorim’ at two of the main fishing grounds of this region. Water temperature data showed the formation of a strong thermocline during summer, from November to April. This thermal gradient, due to the South Atlantic central water (SACW) intrusion that reaches these shallow waters, disappeared with the homogenization of the water column during autumn and winter, from May to September. This cold and low salinity water does not originate from local river discharges, but also represents an advection of sub‐Antartic water mass. After this and during spring, a new thermocline develops, reaching its maximal expression from February to March. A maximal gradient was registered in February 1997, when the temperature dropped from 26°C at 7 m to 16°C at 14 m depth. This result shows that the SACW intrusion is a large‐scale phenomenon that regularly influences the whole inner continental shelf up to 20 m. Demersal fishing grounds located in this area were covered during summer by a cold and nutrient‐rich mass of water that resulted in an unusual maximum of chlorophyll a values near the bottom (30 m). The homogenization of the water column and the presence of another cold water mass during winter resulted in a strong semi‐annual thermal cycle on the bottom. The role of this important oceanographic process in fishery production and dynamics deserves further investigation, but the data presented here show evidence for the importance of this phenomenon.

The distribution, population dynamics and secondary production of the polychaete Euzonus furciferus was studied in Atami Beach (Southern Brazil), from February 1992 to March 1993. Euzonus furciferus Ehlers, 1897 is the only deposit feeder species of the upper intertidal region. The organisms were present in the sandy beach all over the year, concentrated in a narrow band, and reaching maximal densities of 3,029 individuals m-2. Peaks of abundance occurred in September 1992, with a mean of 681.8 individuals m-2. Recruitment occurred in winter, with a peak in July. Mean annual biomass was estimated in 0.218 gAFDW m-2, with a total annual production of 0.466 gAFDW m-2 y-1, giving a P/B ratio of 2.13 y-1. Similar values were found for a filter-feeder polychaete inhabiting the same beach, suggesting that general food disposability of each particular environment is more important for production than the trophic strategic employed by those organisms exploring this environment.

Sandy beaches constitute a key ecosystem and provide socioeconomic goods and services, thereby playing an important role in the maintenance of human populations and in biodiversity conservation. Despite the ecological and social importance of these ecosytems, Brazilian sandy beaches are significantly impacted by human interference, chemical and organic pollution and tourism, as well as global climate change. These factors drive the need to better understand the environmental change and its consequences for biota. To promote the implementation of integrated studies to detect the effects of regional and global environmental change on beaches and on other benthic habitats of the Brazilian coast, Brazilian marine researchers have established The Coastal Benthic Habitats Monitoring Network (ReBentos). In order to provide input for sample planning by ReBentos, we have conducted an intensive review of the studies conducted on Brazilian beaches and summarized the current knowledge about this environment. In this paper, we present the results of this review and describe the physical, biological and socioeconomics features of Brazilian beaches. We have used these results, our personal experience and worldwide literature to identify research projects that should be prioritized in the assessment of regional and global change on Brazilian sandy beaches. We trust that this paper will provide insights for future studies and represent a significant step towards the conservation of Brazilian beaches and their biodiversity.

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