Predation by Nucella lapillus (Linnaeus, 1758) on Littorina obtusata (Linnaeus, 1758) and Mytilus edulis (Linnaeus, 1758)

Prey preference and recognition by individuals of Nucella lapillus from 13 different populations from New England were studied, to determine if individuals of this species kept on a single prey diet develops a preference for this prey, and if prey availability affects prey recognition in this predator. Individuals from all 13 populations showed a preference for Mytilus edulis over Littorina obtusata in laboratory experiments, including those from a population that prey only on L. obtusata in the field. Individuals from another population were not able to recognize L. obtusata as a prey. N. lapillus kept in a diet of M. edulis in the laboratory had its preference for this prey reinforced, but those kept in a diet of L. obtusata, did not develop a preference for this prey. Adults and juveniles of Nucella lapillus showed higher feeding rates on both M. edulis and L. obtusata, in treatments with higher prey density than in those with lower prey density. Nucella lapillus showed a higher growth rate feeding on Mytilus edulis than on Littorina obtusata during a 8 months laboratory experiment. The results indicate that M. edulis presented a greater food value for N. lapillus than L. obtusata. Carcinus maenas appeared for the first time in obvious numbers in Pembroke, Maine in the summer of 1995. C. maenas is a predator of N. lapillus, and experiments were conducted to determine if Nucella lapillus from Pembroke, showed different predation rates on Littorina obtusata in the presence and absence of the green crab Carcinus maenas. Parallel experiments were also done using N. lapillus from Little Harbor, NH population, where the crab has been well established for at least 25 years. In another experiment, the preference of C. maenas between N. lapillus, high spire L. obtusata and low spire L. obtusata was investigated. The predation on L. obtusata was significantly higher in the treatments with N. lapillus from Pembroke than in those with N. lapillus from Little Harbor, in both times the experiment was performed. Small C. maenas were just able to prey on L. obtusata with high spires. Large crabs were able to prey on all three food items, and high spire L. obtusata were successfully attacked most often

Relations between shell size and radula size in marine prosobranchs (Mollusca: Gastropoda)

ABSTRACT The Gastropoda presents the highest adaptative radiation among the mollusks. This characteristic allowed the appearance of many forms of feeding, and with it, many strategies of capture and food processing. In this work, specimens belong to 14 marine prosobranch gastropod species were collected in the coast of Ceará State Northeast Brazil with the purpose to investigate the relation between shell size and radula size in gastropods with different diets and radula type. It was found significative correlations in Cerithium atratum, Collisella subrugosa, Fissurella rosea, Neritina virginea, Olivella minuta, Pisania pusio, Tegula viridula, and Thais haemastoma. Nonsignificative results were found in Littorina flava, Littorina ziczac, Nassarius vibex, Natica marochiensis, Pleuroploca aurantiaca, and Pugilina morio. The species with rhipidoglossate radula and the driller carnivores with rachiglossate radula are the ones that presented significative correlation among shell size and radula size. Other parameters that could influence the radular morphology (besides the radula type or diet) are environment pressure, prey searching and capture strategies and species ontogeny. RESUMO A classe Gastropoda é o grupo que possui a maior radiação adaptativa entre os moluscos. Essa característica permitiu o surgimento de várias formas de alimentação e, com elas, diversas estratégias de captura e processamento do alimento. Neste trabalho, 14 espécies de gastrópodes prosobrânquios marinhos foram coletados no litoral do Estado do Ceará nordeste do Brasil, com o objetivo de analisar a relação entre o tamanho da concha e o tamanho da rádula em animais com diferentes dietas e tipos radulares. O teste revelou correlações significativas em Cerithium atratum, Collisella subrugosa, Fissurella rosea, Neritina virginea, Olivella minuta, Pisania pusio, Tegula viridula e Thais haemastoma. Resultados não significativos forma encontrados em Littorina flava, Littorina ziczac, Nassarius vibex, Natica marochiensis, Pleuroploca aurantiaca e Pugilina morio. As espécies com rádula rhipidoglossa e os carnívoros perfuradores com rádula rachiglossa apresentaram correlação significativa na relação estudada. Outros parâmetros que podem influenciar na morfologia radular (além do tipo de rádula e dieta,) são a pressão do meio, as estratégias de procura e captura da presa e a ontogenia das espécies

Distribution patterns inference of the family Veneridae (Mollusca, Bivalvia) in Brazil through secondary database

Veneridae é considerada uma das maiores famílias do Recente, e também uma das mais diversas dentro de Bivalvia, distribuindo-se tanto em ambiente marinho quanto estuarino. Estudos de cunho biogeográficos são importantes para manejo e conservação da biodiversidade. O trabalho tem como objetivo inferir os padrões de distribuição latitudinais e longitudinais, reunindo e listando a composição de venerídeos para a costa do Brasil a partir de base secundária de dados. A composição e distribuição geográfica foram determinadas a partir de levantamento bibliográfico, bem como acesso a bancos de dados online, e classificadas em padrões de distribuição atuais (latitudinais e longitudinais). Segundo dados da literatura, registram-se 40 espécies para a família no Brasil, sendo observada semelhança na malacofauna de Veneridae entre Brasil, Caribe e Golfo do México. As espécies de venerídeos foram classificadas em oito padrões latitudinais e cinco longitudinais. O trabalho aponta uma provável distribuição da família e indica a necessidade de aprofundar o conhecimento da malacofauna no país.Palavras-chave: biogeografia, heterodonta, venerídeos, Atlântico Ocidental.Veneridae is one of the largest families of Recent, also one of the most diverse within Bivalvia, being found in marine and estuarine environments. Biogeographic studies are important for the management and conservation of the biodiversity. This paper aims at inferring the latitudinal and longitudinal distribution patterns, gathering and listing Veneridae composition for the Brazilian coast through secondary database. The composition and geographical distribution were determined through literature, as well as access to online databases, and classified as current distribution patterns (latitudinal and longitudinal). According to the collected data, there are 40 species of the family recorded in Brazil; there were similarities among Brazil, the Caribbean and the Gulf of Mexico. The Veneridae species was classified into eight latitudinal and five longitudinal patterns. This work points to a probable family distribution and highlights the need for better understanding of the malacofauna in the country.Keywords: biogeography, heterodonta, Venus clam, Western Atlantic

Competitive interactions among zoanthids (cnidaria: zoanthidae) in an intertidal zone of northeastern Brazil

A competição por espaço é comum em organismos sésseis que vivem em substrato consolidado. Os corais apresentam muitas estratégias para competição por espaço, incluindo danos ao oponente ou inibição do crescimento. No presente estudo, as interações competitivas entre três espécies de zoantídeos foram investigadas em um ambiente de recifes de arenito no nordeste brasileiro. As habilidades competitivas dos zoantídeos foram analisadas por observações periódicas das margens de contato entre as colônias em ambiente natural e avaliação experimental da taxa de crescimento, através da remoção de uma área de 100 cm² de colônias de cada espécie. Palythoa caribaeorum e Zoanthus sociatus apresentaram taxa de crescimento similar, crescendo mais rápido que Protopalythoa variabilis. A estratégia de colonização parece ser diferente entre as espécies. As margens de contato entre P. caribaeorum e Z. sociatus permaneceram inalteradas ao longo do tempo, sem qualquer interação agressiva entre as colônias, sugerindo que a inibição do crescimento foi a estratégia utilizada. Palythoa caribaeorum e Z. sociatus cresceram entre os pólipos de P. variabilis, muitas vezes sufocando e matando suas colônias. A coexistência entre os zoantídeos revela uma capacidade de sobrevivência frente a recursos limitados, como substrato livre, o que levou ao sucesso na colonização e estabelecimento de zoantídeos em ambientes intertidais.Sessile organisms that live in consolidated substrates frequently compete for space. Coral species have many strategies to face this competition, including harming their opponents or hindering their growth. In the present study, the competitive interactions between three species of zoanthids were investigated in the intertidal zone of a sandstone reef environment in northeastern Brazil. The competitive abilities of the three species were evaluated by periodic observation of the natural fringes of contact and experimental evaluation of their growth rate through removal of 100 cm² of colonies of each species. Palythoa caribaeorum and Zoanthus sociatus had similar growth rates, and both species grew faster than Protopalythoa variabilis. The recolonization strategy seems to differ among species. The contact fringes between P. caribaeorum and Z. sociatus remained unchanged over time, without any type of aggressive interaction between them, suggesting that stand-off was the strategy used by these organisms. Palythoa caribaeorum and Z. sociatus grew among the polyps of P. variabilis, often killing its colonies. The coexistence of zoanthids reveals a capacity for survival in the face of competition for limited resources such as free substrate, which led to the colonization and establishment of zoanthids in intertidal environments

First record of Pentapycnon geayi Bouvier, 1911 (Pycnogonida: Pycnogonidae) in the state of Ceará, northeastern Brazil

Contributions to the knowledge of the Pycnogonida fauna along the Brazilian coast are scarce. There are only 60 records for the coast of Brazil, and reports of this fauna are notably discontinuous. This is the first record of Pentapycnon geayi Bouvier, 1911 (Pycnogonida: Pycnogonidae) in the state of Ceará. This study adds a new bathymetric record and fills a gap in the distribution of P. geayi along the Brazilian coast. This report also provides important new data for Ceará because the diversity of Pycnogonida in this state is practically unknown

Descripción de las cápsulas ovígeras de Voluta ebraea Linnaeus, 1758 (Gastropoda: Neogastropoda)

Voluta ebraea Linnaeus, 1758 es un volútido endémico del norte y nordeste de Brasil. Ovicápsulas características de la familia Volutidae fueron encontradas adheridas al alga Udotia occidentalis en praderas de fanerógamas marinas. La morfología y tamaño de las ovicápsulas y embriones, así como la rádula y protoconcha de juveniles y adultos confirman que las puestas encontradas corresponden a V. ebraea. Las ovicápsulas son circulares y aplanadas con un diámetro medio de 18,2 mm, presentando morfología y tamaños similares a las ovicápsulas de Voluta musica, endémica de Venezuela. Las ovicápsulas presentan una apertura en el centro (por donde emergen los juveniles) y una sutura desde ésta hasta la base. En promedio eclosionaron tres juveniles por ovicápsula, con un largo promedio de 7,8 mm. Las técnicas histoquimicas realizadas demostraron que la pared de las ovicápsulas está compuesta por tres capas, conteniendo proteínas, carbohidratos y glicoproteínas. La identificación y protección de las ovicápsulas de V. ebraea encontradas en el campo podría ayudar a conservar esta especie endémica y amenazada.Voluta ebraea Linnaeus, 1758 is an endemic volutid from north and northeast Brazil. Characteristic volutid egg capsules were found attached to the alga Udotia occidentalis in sea grass beds. Morphology and size of those egg capsules and embryos as well as protoconch and radulae of juvenile and adults confirm that all the spawns found belong to V. ebraea. Egg capsules, are circular and flattened with a mean diameter of 18.2 mm, presenting analogous morphology and size to those of Voluta musica, endemic from Venezuela. An opening through which crawling juveniles emerge is located at the center of the egg capsules with a suture from the base to the central opening. The average number of hatchlings was three and the mean shell length of juveniles 7.8 mm. Histochemical techniques showed that egg capsules wall is composed of three layers, containing protein, carbohydrates and glycoprotein. Identifying and protecting V. ebraea egg capsules in the wild could help to conserve this endemic and endangered species.Fil: Matthews-Cascon, Helena. Departamento de Biologia, Centro de Ciências, Universidade Federal do Ceará; BrasilFil: Rocha-Barreira, Cristina. Instituto de Ciências do Mar (Labomar) Universidade Federal do Ceará; BrasilFil: Penchaszadeh, Pablo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Bigatti, Gregorio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentin

Distribución espacial de cangrejos del género Uca en un mangle tropical en el nordeste de Brasil

The influence of abiotic factors on the spatial distribution of the fiddler crabs Uca leptodactyla, U. maracoani, U. rapax and U. thayeri was studied in a tropical mangrove of northeast Brazil. Eight transects were delimited in a mangrove area of the Pacoti River. On each transect, three 0.25 m2 squares were sampled during spring low tide periods from September 2003 to August 2004. The sediment of the squares at each transect was analysed for grain size, organic matter and humidity. Morphology of the second maxilliped was studied considering the number of spoon-tipped setae to help explain the ecological distribution of the species. U. leptodactyla and U. rapax were found living in medium sand, U. thayeri was collected in fine and very fine sand, while U. maracoani was found living in very fine sand. U. leptodactyla showed a negative correlation with organic matter and humidity while U. thayeri showed a positive correlations for both factors. U. maracoani and U. rapax were not correlated with organic matter or humidity. The analysis of the second maxilliped revealed that U. leptodactyla and U. rapax show a high quantity of spoon-tipped setae while U. maracoani and U. thayeri show a greater quantity of plumose setae.La influencia de los factores abióticos sobre la distribución espacial de los cangrejos Uca leptodactyla, U. maracoani, U. rapax y U. thayeri fue estudiada en un mangle tropical en el Nordeste de Brasil. Se muestrearon mensualmente con tres cuadrantes (0.25 m2) en ocho áreas diferentes (transectos) de lo Mangle del Río Pacoti entre septiembre de 2003 y agosto de 2004. Las propiedades físicas del sedimento, i.e., textura, contenido orgánico y humedad también fueron evaluadas en cada cuadrante. La morfología del segundo maxilipedio se estudió considerado el número de setas con punta de cuchara para explicar la distribución ecológica de las especies. U. leptodactyla y U. rapax fueron encontrados en los sedimentos gruesos, mientras U. thayeri y U. maracoani fueron encontrados en los sedimentos lodosos. La abundancia de U. leptodactyla mostró una correlación negativa con el contenido orgánico y la humedad mientras U. thayeri mostró una correlación positiva con ambos factores. La abundancia de U. rapax y U. maracoani no estuvo correlacionada con la materia orgánica y humedad. El análisis del segundo maxilipedio reveló que U. leptodactyla y U. rapax presentan una cantidad alta de setas con punta de cuchara mientras U. maracoani y U. thayeri presentaron una cantidad mayor de setas plumosas.

Mollusks from two estuarine areas in Ceará state, northeastern Brazil, with new state records for four species

We analyzed qualitatively the malacofauna found in the tidal zones of Banco dos Cajuais and Ilha Grande estuarine complex, both in Ceará State, northeastern Brazil. Qualitative data on the malacofauna from Banco dos Cajuais and the Ilha Grande estuarine complex were obtained by systematic sampling in 2008 and 2009 during field activities for the “Migratory Shorebirds Conservation and Shrimp Farming in Northeast Brazil” project. Twenty-two species of mollusks (13 bivalves and 9 gastropods) were found in Banco dos Cajuais, and 25 species (18 bivalves and 7 gastropods) were found in the Ilha Grande estuarine complex. Four species, Lucina muricata (Spengler, 1798), Tagelus divisus (Lightfoot, 1786), Crassinella martinicensis (d’Orbigny, 1853), and Periploma ovata Kuroda and Horikoshi, 1958 were recorded from Ceará for the first time

An extended geographical distribution of Donax gemmula Morrison, 1971 (Bivalvia: Donacidae): new record from the Brazilian Northeastern coast

This study provides the first record of Donax gemmula Morrison, 1971 (Bivalvia: Donacidae) from the Ceará State, Northeast Brazil; up to now it was only known from the Southeastern and Southern Brazilian coast. Shells larger than ~2 mm in length of this species can be distinguished from those of D. striatus Linnaeus, 1767. Both species were collected in the same beaches: Banco dos Cajuais and Pecém. The occurrence of D. gemmula remains unnoticed for others States of the Northeast Brazil, and so we suggest two possible explanations for this finding from Ceará State: i) a recent introduction (e.g., by ballast water); or ii) this species has a continuous distribution along the Brazilian coast (Ceará to Rio Grande do Sul), being not recorded until now because this is not easily collected (the animals are small and bottom samples need to be sieved to obtain them) and may be confused with young specimens of other species of Donax, such as D. striatus