Abstract The ecological and ethnological aspects of the harvesting of the cockle, Leukoma pectorina (Bivalvia: Veneridae), were investigated on Algodoal-Maiandeua Island, on the Amazon coast of Brazil. Ethnobiological data were collected through informal conversations, semi-structured interviews, and observations of the harvesting and processing of bivalves on the island. Following the ethnobiology study, the cockle beds were surveyed to evaluate the density of L. pectorina, body size and the meat yield of the cockles in the months of dry and rainy seasons. In the study area, cockling is a manual and artisanal activity, and L. pectorina is typically harvested by mothers with little formal education. The cocklers make their own tools, cockles are prepared in the family environment, and the majority of the catch is sold to commercial establishments on the island. Cockling is a sporadic activity used to complement the family income, and is more common during the dry season, when tourism increases on Algodoal-Maiandeua Island. The cockles are also larger and population density is higher during this season, and the cocklers themselves recognize this period as providing the most productive harvest. These findings reinforce the value of traditional knowledge for both scientific research and the planning of the management of coastal fishery resources.

Abstract This study shows the condition index (CI) of the clam Chionista fluctifraga in three different size groups (small <30 mm, medium 30 mm - 40 mm, and large > 40 mm) harvested monthly during one year in a commercial fishery (Sonora, Mexico). Temperature, salinity, oxygen, chlorophyll a, particulate organic and inorganic concentrations were recorded once-a-month at the study site. Significant differences of CI were detected; higher for small clams (26.5 ± 3.4), followed by medium (24.0 ± 3.0) and large clams (20.2 ± 3.0). High and moderate correlations (Pearson) of temperature and CI were observed in small and medium clams. Thus, temperature was the variable affecting CI the most and this was detected during the period corresponding to reproduction and nutrient storage of the species. In relation to these processes, the CI reflected a different nutritional value for each group of clams; high for small, moderate for medium animals, and low for large individuals. This may serve to producers when selecting clams with high condition and planning harvesting.

Resumen Este estudio muestra el índice de condición (IC) de la almeja Chionista fluctifraga en tres diferentes grupos de talla (pequeñas < 30 mm, medianas 30- 40 mm, y grandes > 40 mm) cosechadas mensualmente durante un año de una pesquería comercial (Sonora, México). La temperatura, salinidad, oxígeno, clorofila a, material orgánico e inorgánico particulado fueron registrados mensualmente en el sitio de estudio. Se detectaron diferencias significativas del IC; mayores para almejas pequeñas (26.5 ± 3.4), seguidas por las medianas (24.0 ± 3.0) y grandes (20.2 ± 3.0). Correlaciones (Pearson) altas y moderadas de temperatura e IC fueron observadas en almejas chicas y medianas. Consecuentemente, la temperatura fue la variable que más afectó el IC y esto fue detectado durante el periodo correspondiente a la reproducción y almacenamiento de nutrientes de esta especie. Con relación a estos procesos, el IC reflejó diferente valor nutritivo para cada grupo de almejas; alto para chicas, moderado para animales medianos y bajo para individuos grandes. Esto puede servir a los productores para seleccionar almejas con alta condición y planear las cosechas.

Resumo: Os ecossistemas costeiros do nordeste do Brasil têm uma importante biodiversidade de moluscos marinhos, a qual ainda é insuficientemente estudada. Este trabalho representa um inventário dos moluscos em duas localidades no estuário do Rio Paraíba. Moluscos foram coletados entre 2014 e 2016 na costa e área de restinga localizadas nas propriedades de Treze de Maio e Costinha de Santo Antônio. Este levantamento malacofaunístico identificou 12 famílias, 20 gêneros e 21 espécies de bivalves, 17 famílias, 19 gêneros e 20 espécies de gastrópodes e uma espécie de cefalópode. Os bivalves da família Veneridae Rafinesque, 1815 foram os mais representativos com um total de cinco espécies. Os gastrópodes da família Littorinidae Children, 1834 apresentaram a mais alta riqueza de espécies. As espécies mais abundantes foram: Neritina virginea (Linnaeus, 1758), Brachidontes exustus (Linnaeus, 1758), Crassostrea brasiliana (Lamarck, 1819), Cerithium atratum (Born, 1778), Anomalocardia brasiliana (Gmelin, 1791), Parvanachis obesa (C. B. Adams, 1845), Phrontis polygonata (Lamarck, 1822), Littoraria angulifera (Lamarck, 1822), L. flava (King, 1832), Tagelus plebeius (Lightfoot, 1786), Echinolittorina lineolata (d'Orbigny, 1840) e Iphigenia brasiliensis (Lamarck, 1818). Os resultados mostram que a área estudada tem uma considerável riqueza de espécies de Mollusca, necessitando de monitoramento ambiental, principalmente devido à importância econômica de algumas espécies para a população local.

Abstract: Coastal ecosystems of northeastern Brazil have important biodiversity with regard to marine mollusks, which are insufficiently studied. Here we provide an inventory of mollusks from two sites in the estuary of the Paraíba River. Mollusks were collected in 2014 and 2016 on the coast and sandbanks located on the properties of Treze de Maio and Costinha de Santo Antônio. The malacofaunal survey identified 12 families, 20 genera and 21 species of bivalves, 17 families, 19 genera and 20 species of gastropods and one species of cephalopod. Bivalves of the family Veneridae Rafinesque, 1815 were the most representative, with a total of five species. Gastropods of the family Littorinidae Children, 1834 had the greatest species richness. The most abundant species were: Neritina virginea (Linnaeus, 1758), Brachidontes exustus (Linnaeus, 1758), Crassostrea brasiliana (Lamarck, 1819), Cerithium atratum (Born, 1778), Anomalocardia brasiliana (Gmelin, 1791), Parvanachis obesa (C. B. Adams, 1845), Phrontis polygonata (Lamarck, 1822), Littoraria angulifera (Lamarck, 1822), L. flava (King, 1832), Tagelus plebeius (Lightfoot, 1786), Echinolittorina lineolata (d'Orbigny, 1840) and Iphigenia brasiliensis (Lamarck, 1818). The results show that the study area has considerable species richness of Mollusca, requiring environmental monitoring in the region mainly due to the economic importance of some species to the local population.

Sedimentological and paleontological study of the Man Aike Formation at the Estancia 25 de Mayo, SW of Santa Cruz Province, Argentina, represents the evolution of an incised valley from fluvial to marine environment during the late middle Eocene. At the base of the unit there is an unconformity that corresponds to fluvial channels which cut down into the underlying Maastrichtian sandstones of the Calafate Formation. The fauna of invertebrates (mostly molluscs) illustrated herein was collected from shell beds interpreted as tidal ravinement surfaces. The fauna includes terebratulid brachiopods, bivalves of the families Malletiidae, Mytilidae, Pinnidae, Ostreidae, Pectinidae, Carditidae, Crassatellidae, Lahillidae, Mactridae, Veneridae, and Hiatellidae, and gastropods of the families Trochidae and Calyptraeidae, and a member of Archaeogastropoda of uncertain affinities. The similarities of this fauna with that recorded in the Upper Member of the Río Turbio Formation, together with 87Sr/86Sr ages, suggest a late Middle Eocene age for the Man Aike Formation.

Los estudios sedimentológicos y paleontológicos realizados en rocas asignadas a la Formación Man Aike, expuestas en la estancia 25 de Mayo, al sur de Calafate, provincia de Santa Cruz, Argentina, sugieren que esta unidad representa la evolución de un valle inciso desde ambientes fluviales a marinos durante el Eoceno medio tardío. En la base de la sucesión se registra una discordancia que corresponde a canales fluviales que cortan a las areniscas maastrichtianas de la Formación Calafate. La fauna de invertebrados (mayormente moluscos) ilustrada en este trabajo fue coleccionada de capas de conchillas que se interpretan como parte de diferentes superficies de ravinement mareal. La fauna incluye braquiópodos terebratúlidos, bivalvos de las familias Malletiidae, Mytilidae, Pinnidae, Ostreidae, Pectinidae, Carditidae, Crassatellidae, Lahillidae, Mactridae, Veneridae e Hiatellidae y gasterópodos de las familias Trochidae y Calyptraeidae y un miembro de Archaeogastropoda con afinidades inciertas. Las similitudes de esta fauna con aquellas registradas en el Miembro Superior de la Formación Río Turbio, junto con dataciones 87Sr/86Sr, sugieren para la Formación Man Aike una edad eocena media tardía.

Se estudió la dinámica poblacional de la almeja Megapitaria squalida de setiembre 2002 a febrero 2003 en Bahía Magdalena, México. La densidad se determinó en un sitio no explotado y dos sitios explotados utilizando transectos perpendiculares desde la línea costera. También se entrevistó a pescadores locales de diferentes partes de la bahía para obtener información acerca de la pesquería artesanal y recreacional de M. Squalida. La densidad promedio estimada fue de 2.01±1.41 ind/m², sin diferencias significativas entre sitios. La relación de masa y longitud total fue de Mtot = 0.0001*SL3.1644 (r² = 0.9804, n = 92) y la relación de masa y longitud de tejido fue de Mtis = 0.0002*SL2.7144 (r² = 0.945, n = 92). Los parámetros de crecimiento Von Bertalanffy se determinaron utilizando marcadores individuales. Hay grandes diferencias en crecimiento tanto interindividuales como estacionales. Los valores anuales promedio fueron: K = 0.655, L∞ = 83 mm. Debido a que la longitud de la concha puede superar los 135 mm en aguas profundas, es necesario considerar las poblaciones intermareal e inframareal de manera separada. La mortalidad promedio total (Z) fue de 1.61 y-1. No se calculó la mortalidad de pesca porque la mortalidad total (Z) del sitio no explotado fue mayor que la de sitios explotados. Aparentemente M. squalida migra hacia aguas más profundas al crecer. No se encontró evidencia de que estas poblaciones estén sobreexplotadas.

The population dynamics of an intertidal population of Megapitaria squalida was studied from September 2002 to February 2003 in Bahía Magdalena, Mexico. To obtain information about the artisanal and recreational fishery of M. squalida, local fishermen at different parts of the bay were interviewed. Clam densities were determined at one unexploited and two exploited sites along perpendicular transects from the shore line. Average clam density was 2.01±1.41 ind/m², densities did not differ significantly between the three sampling sites. The length-total mass relation was Mtot = 0.0001*SL3.1644 (r2 = 0.9804, n = 92) and the length-tissue mass relation was Mtis = 0.0002*SL2.7144 (r² = 0.945, n = 92). Von Bertalanffy-growth parameters were determined using marked individuals. Strong interindividual and also seasonal differences in growth were observed. Average annual values were: K = 0.655, L∞ = 83 mm. Since M. squalida can reach a shell length of more than 135 mm in deeper waters, it is necessary to consider intertidal and subtidal populations separately. Average total mortality (Z) was 1.61 y-1. No fishing mortality was calculated because total mortality Z at the unexploited control site was higher than Z at the exploited sites. It appears that M. squalida migrates into deeper water with increasing shell length, as average shell length increased at lower tidal levels and marked specimens showed a clear migration towards deeper waters. As yet no overexploitation could be found in the study area. Rev. Biol. Trop. 54 (3): 1003-1017. Epub 2006 Sept. 29.

Coletas intensivas da fauna bentônica marinha da costa norte do Estado de São Paulo, realizadas pelos programas de pesquisa "Fauna de Praia/UNICAMP" de agosto de 1995 a julho de 1997 e "Biota/FAPESP" de março de 2001 a dezembro de 2002 recolheram 2769 exemplares pertencentes a dezesseis espécies, doze gêneros e sete subfamílias. A caracterização de cada espécie foi ampliada com redescrição e ilustrações detalhadas, baseadas nos caracteres da concha. Tabelas comparativas dessas características e uma chave dicotômica de identificação das subfamílias são apresentadas neste estudo.

This study concerns the Veneridae bivalves sampled during the research programs "Fauna de Praia/UNICAMP" and "Biota/FAPESP" carried out between August 1995 and July 1997 and between March 2001 and December 2002 respectivelly, in the north coast of São Paulo State, Brazil. A total of 2769 individuals belonging to sixteen species, twelve genera and seven subfamilies were recorded and the characterization of each species improved with detailed redescription and illustrations based on the shell characters. Comparative tables and a identification dichotomic key for subfamilies focused in this study are provided.

Protothaca (Leukoma) pectorina (Lamarck, 1818) lives from the West Indies to Santa Catarina State, Brazil, in soft muddy beaches in quiet waters of protected bays with little amounts of suspended material. A study of the functional anatomy of P. pectorina and its ecological aspects were undertaken. The anatomy and functioning of the stomach and the mechanisms for selection of particles were observed. The siphons, ctenidia, labial palps and stomach were analised and related to the animal's natural environment. The siphons belong to type B (Yonge 1948), the ctenidia to type C (1a) (Atkins 1937). The ctenidia are homorhabdic (Ridewood 1903) and the stomach belongs to type V (Purchon 1960).