A. Cecília Z. Amaral

Along‐ and across‐shore components of the spatial distribution of the clam Tivela mactroides (Born, 1778) (Bivalvia, Veneridae)

Beach clam fisheries often provide an alternate income for traditional fishermen, but this activity is highly vulnerable to urbanization of coastal areas. Tivela mactroides is a beach clam commonly harvested in the Caribbean (Venezuela) and on the south‐eastern Brazilian coast. Only localized records on its spatial structure in size and abundance are available to support management of this clam. The present study showed that the spatial distribution in abundance and size of T. mactroides in Caraguatatuba Bay, state of São Paulo, Brazil, has both along‐ and across‐shore (intertidal and subtidal) components. The nature of this distribution should be taken into account in the design of further population or monitoring studies concerning this species. Clam density varied along‐shore, with a tendency towards higher numbers of individuals in the stations near the northern side of river mouths of this bay. Lower densities were related to the occurrence of sea‐stars and sand‐dollars. The intertidal and subtidal across‐shore distribution of clam abundance and size varied between and within areas (southern and northern). The individuals from the southern area were concentrated at intermediate tidal levels (0.2–0.6 m in relation to mean low water), whereas in the northern area the clams were more homogeneously distributed. The uppermost limit of their distribution was 0.8 m (southern) and 0.4 m (northern), and an upwards tendency towards increased size was more evident in the northern area. In the subtidal, abundance and individual size tended to increase from the deepest (4.5 m) to the shallowest (0.5 m) levels only in the southern area. Individual clams in the northern area tended to be smaller and more abundant than in the southern area. The species had an ontogenic distribution: small‐sized individuals were recorded only in the subtidal. Possible causes for these patterns and for the differences between areas (human exploitation, organic pollution, beach morphodynamics, differential recruitment, and adult–larvae interactions) are discussed, and specific studies are suggested to evaluate formally the proposed hypotheses.

Spatial distribution of mollusks in the intertidal zone of sheltered beaches in southeastern of Brazil

The spatial distribution of mollusks in the intertidal zone was examined monthly from August 1995 through July 1997, in Enseada, Barra Velha and Araca beaches in southeastern of Brazil. One study sector was selected in Enseada and Barra Velha, and two sectors in Araca (Araca I and Araca II). The sectors were 10 m wide and equivalent in length to the width of the intertidal zone. Each sector was divided into three horizontal levels: lower, middle and upper, where the samples were taken with a cylinder corer with a base area of 0.16 m2. In order to characterize the intertidal environment in these areas, some environmental variables were analyzed. In general, the mollusks were distributed in the sectors as follows: Enseada - Olivella minuta (Link, 1807) in the lower level and Tagelus plebeius (Lightfoot, 1786) in the upper level; Araca I - O. minuta in the lower level, Tellina lineata Turton, 1819 and Anomalocardia brasiliana (Gmelin, 1791) in the middle levels; Araca II - Cerithium atratum (Born, 1778) in the lower level, O. minuta in the lower and middle levels, and A. brasiliana and Corbula caribaea Orbigny, 1842 in the middle level; Barra Velha - Tagelus divisus (Spengler, 1794), Lucina pectinata (Gmelin, 1791) and Tellina versicolor De Kay, 1843 in the lower level, and A. brasiliana and Macoma constricta (Bruguiere, 1792) in the upper level. The intertidal zone of the study sectors could be divided into two biological zones: the upper zone, where T. plebeius, A. brasiliana and M. constricta were more abundant; and the lower zone, where O. minuta, C. atratum, T. lineata, T. versicolor, C. caribaea, T. divisus and L. pectinata were abundant.

Contribuição ao conhecimento da fauna de peixes do litoral norte do Estado de São Paulo

Na execucao de um programa de levantamento das faunas demersal e epibentonica da plataforma do litoral norte do Estado de Sao Paulo, foram tomadas, em um periodo de dois anos, 28 amostras da fauna de fundo, utilizando-se redes tipo ottertrawl abrangendo a area compreendida entre as ilhas Anchieta, Vitoria e das Couves. A despeito do pequeno tamanho das redes - 30 pes na tralha de boia -, os resultados, quanto a numero e diversidade dos peixes encontrados na area, pareceram ser muito significativos e justificar a comunicacao atual. Um total de 97 especies de peixes, tanto osseos quanto cartilaginosos, foi obtido em 28 capturas controladas, durante os anos de 1978 e 1979, A familia melhor representada foi, como previsto, a dos Sciaenidae; porem, representantes de Rajidae, Bothidae e Cynoglossidae foram tambem abundantes. Lophius gastrophysus e Merluccius hubbsii, ocorreram apenas em profundidades acima de 30 m, o que concorda com sua distribuicao conhecida na costa do extremo sul do pais, Uma lista sistematica das especies e seus nomes populares, quando disponiveis, e dada.

In situ ingestion of microfibres by meiofauna from sandy beaches

Microfibres are widespread contaminants in marine environments across the globe. Detecting in situ ingestion of microfibres by small marine organisms is necessary to understand their potential accumulation in marine food webs and their role in marine pollution. We have examined the gut contents of meiofauna from six sandy beaches in the Atlantic Ocean and the Mediterranean. Out of twenty taxonomic groups, three species of the common sandy beach annelid Saccocirrus displayed in situ ingestion of microfibres in all sites. Laboratory observations showed that species of Saccocirrus are able to egest microfibres with no obvious physical injury. We suggest that their non-selective microphagous suspension-feeding behaviour makes Saccocirrus more prone to ingest microfibres. Although microfibres are rapidly egested with no apparent harm, there is still the potential for trophic transfer into marine food webs through predation of Saccocirrus.

Population biology and secondary production of the stout razor clam Tagelus plebeius (Bivalvia, Solecurtidae) on a sandflat in southeastern Brazil

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, Sao Sebastiao, state of Sao 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.

Anelídeos poliquetos da região de Ubatuba (SP): padrões de distribuição geográfica

This work constitutes a systematic survey of the Annelida Polychaeta from the sublitoral of the Sao Paulo State coast (Ubatuba), southeast Brazil. From 105 identified species, 20 are new records for the brazilian coast. An analysis of affinity degree between the fauna of the studied region and of the adjacents biogeographic provinces shows that 25,5% of the species are endemic for the Paulista Province, 19,0% amphi-american, 17,0% cosmopolite and 16,8% amphi-atlantic. An affinity with species from the Patagonian (7,4%) and Caribbean (2,0%) Provinces is smaller than that of other authors, for the southeast Brazilian coast.

Breve caracterização dos gêneros da familia Capitellidae Grube (Annelida, Polychaeta) e descrição de Nonatus longilineus gen. sp. nov

Nonatus longilineus gen. sp. nov., here described has been found on the southern coast of Brazil. Forty genera of Capitellidae are also recognized and characterized.

Saccocirridae (Annelida) from the southern and southeastern Brazilian coasts

Pharyngocirrus gabriellae (Du Bois-Reymond Marcus 1946) and Saccocirrus pussicus Du Bois-Reymond Marcus 1948 are redescribed based on newly collected material from the south and southeastern Brazilian coasts. Neotypes are designated, since no type material was formally indicated in the original descriptions. New morphological information on the muscular ventral pharynx, ciliation, chaetae and pygidium is provided. Pharyngocirrus gabriellae is additionally characterised by the presence of mouth ciliary patches, capillary lyrate chaetae with a single median tooth and equally bifid medium chaetae with denticulate prongs. The novel diagnostic characters of Saccocirrus pussicus include the absence of a pharynx and the presence of 1–3 pygidial, adhesive ridges and 20 fertile segments. The two species live in very distinct interstitial habitats, with varying hydrodynamics. Pharyngocirrus gabriellae is found at sheltered intertidal and shallow areas in sediments with a redox layer, whereas Saccocirrus pussicus prefers the swash zone of exposed, oxygenated, reflective beaches. Morphology and habitat preferences of P. gabriellae and S. pussicus are consistent with other Saccocirridae species from the ‘Pharyngocirrus’ and ‘Saccocirrus’ genera, respectively.

Anelídeos poliquetos associados ao briozoário Schizoporella unicornis (Johnston): V. Syllidae

Seven species of Syllidae (Annelida, Polychaeta) inhabiting colonies of the bryozoan Schizoporella unicornis (Johnston), a common species on the beaches of Ubatuba and Sao Sebastiao, Sao Paulo State, Brazil are described: Exogone occidentalis Westheide, 1974; Haplosyllis spongicola (Grube, 1855); Opistosyllis corallicola Hartmann-Schroder, 1965; Syllis gracilis (Grube, 1840); Trypanosyllis taeniaformis (Haswell, 1866); Typosyllis maculata Imajima, 1966 and Typosyllis variegata (Grube, 1860). Among these, E. occidentalis, O. corallicola, T. taeniaformis and T. maculata are cited for the first time for the Brazilian coast. The most abundant of these species was S. gracilis.

Patterns of diversity in marine Gastrotricha from Southeastern Brazilian Coast is predicted by sediment textures

Broad spatial variations of biodiversity are associated with patterns and processes at different scales, and are well known for large terrestrial animals. For the interstitial microscopic fauna a wide distribution conception is accepted for several phyla. This assumption is being revised since more information has become available on their biogeography and general macroecological threats. This study analyzed the variability of marine Gastrotricha diversity among benthic habitats and localities along the Brazilian coast. We tested the hypothesis that sediment textures, location, tidal zones, and their interactions, are potential explanatory variables that affect the Gastrotricha diversity. Richness estimates, species composition, and beta diversity were used as response variables of biodiversity. The number of gastrotrichs, macrodasyids, and chaetonotids species was mostly explained by sediment sorting and the highest richness was detected in poorly sorted sediments. Species composition and beta diversity were correlated with tidal zone, location, and average grain size, and the highest turnover of species was expected on islands. The general diversity patterns observed in our study that were explained by sediment textures, tidal zones, and localities, are expected to be observed along other marine coastlines in the world and may be correlated with sediment transport and deposition processes.