Ecology of the non-native snail Sinotaia cf quadrata (Caenogastropoda: Viviparidae). A study in a lowland stream of South America with different water qualities

ABSTRACT Sinotaia quadrata is a snail native from Asia recorded for the first time in South America in 2009 in central Argentina. In 2015, this species was also found in a lowland stream with different water qualities. Our aims were to contribute to the knowledge of its population ecology and to compare the individuals from the two locations anatomically. Snails were searched at 6 sites, where physicochemical and hydraulic parameters were measured. Biological samples were also taken at two sites (S3 and S4) to study the population traits of S. cf quadrata (density, size structure, fecundity and sex ratio) and to assess the water quality through macroinvertebrates' biological indices (richness, diversity and IBPamp). Physicochemical and biological parameters allowed us classifying sites as "moderately polluted" (S3) and "heavily polluted" (S4). At S4, the population showed a lower density, larger individuals, higher fecundity and a scarce representation of young snails. The differences observed in the radula and mantle border of snails from the two geographical regions might be attributed to environmental differences. We conclude that this species is tolerant to a wide range of environmental variables which, along with its high fecundity and morphological plasticity, could allow this species to colonize neighbor streams.

Abundance of the reef-building Petaloconchus varians (Gastropoda: Vermetidae) on intertidal rocky shores at Ilha Grande Bay, southeastern Brazil

ABSTRACT The reef-building vermetid Petaloconchus varians occurs in the western Atlantic Ocean, from the Caribbean Sea to the southern coast of Brazil. The present study evaluated the abundance of P. varians on intertidal rocky shores in Ilha Grande Bay (Rio de Janeiro State), and characterized their reefs, describing the species density, besides the weight and the belt width of the reefs. Petaloconchus varians reefs were recorded at 25 sites, with rocky shores exposed to different wave action (very sheltered, sheltered, semi-exposed and exposed) and slopes (10° to 46°). Clusters of individuals constructed large reefs along the middle intertidal zone, creating a wide belt (38 cm to 2 m). The density of P. varians and the weight of the reefs ranged from 620 to 2,559 ind.100 cm-2 and from 100 to 1,500 g.100 cm-2, respectively. Considering that the species was last reported from the area in the mid-20th century, the present study suggests that P. varians reefs are becoming dominant in the intertidal zone of rocky shores in Ilha Grande Bay. This is a contribution to knowledge of this ecosystem in Ilha Grande Bay, in view of local or global ecological changes.

Changes in body size spectra of benthic caridean shrimps (Decapoda: Caridea) and snails (Gastropoda) as response to seasonal variability

AbstractEcologists have been largely interested in the description and understanding of the power scaling relationships between body size and abundance of organisms. Many studies have focused on estimating the exponents of these functions across taxonomic groups and spatial scales, to draw inferences about the processes underlying this pattern. The exponents of these functions usually approximate -3/4 at geographical scales, but they deviate from this value when smaller spatial extensions are considered. This has led to propose that body size-abundance relationships at small spatial scales may reflect the impact of environmental changes. This study tests this hypothesis by examining body size spectra of benthic shrimps (Decapoda: Caridea) and snails (Gastropoda) in the Tamiahua lagoon, a brackish body water located in the Eastern coast of Mexico. We measured water quality parameters (dissolved oxygen, salinity, pH, water temperature, sediment organic matter and chemical oxygen demand) and sampled benthic macrofauna during three different climatic conditions of the year (cold, dry and rainy season). Given the small size of most individuals in the benthic macrofaunal samples, we used body volume, instead of weight, to estimate their body size. Body size-abundance relationships of both taxonomic groups were described by tabulating data from each season into base-2 logarithmic body size bins. In both taxonomic groups, observed frequencies per body size class in each season were standardized to yield densities (i.e., individuals/m3). Nonlinear regression analyses were separately performed for each taxonomic group at each season to assess whether body size spectra followed power scaling functions. Additionally, for each taxonomic group, multiple regression analyses were used to determine whether these relationships varied among seasons. Our results indicated that, while body size-abundance relationships in both taxonomic groups followed power functions, the parameters defining the shape of these relationships varied among seasons. These variations in the parameters of the body size-abundance relationships seems to be related to changes in the abundance of individuals within the different body size classes, which seems to follow the seasonal changes that occur in the environmental conditions of the lagoon. Thus, we propose that these body size-abundance relationships are influenced by the frequency and intensity of environmental changes affecting this ecosystem. Rev. Biol. Trop. 64 (1): 33-44. Epub 2016 March 01.

ResumenLos ecólogos han estado muy interesados en describir y comprender las relaciones escalares de potencia entre el tamaño corporal y la abundancia de los organismos. Muchos estudios se han centrado en la estimación de los exponentes de estas funciones a través de grupos taxonómicos y escalas espaciales, para sacar conclusiones acerca de los procesos que subyacen a este patrón. Los exponentes de estas funciones generalmente se aproximan -3/4 a escalas geográficas, pero se apartan de este valor cuando se consideran extensiones espaciales más pequeñas. Esto ha llevado a proponer que las relaciones tamaño corporal-abundancia en pequeñas escalas espaciales puede reflejar el impacto de cambios ambientales. Este estudio pone a prueba esta hipótesis mediante el examen de los espectros de tamaño corporal de camarones bentónicos (Decapoda: Caridea) y caracoles (Gastropoda) en la laguna de Tamiahua, un cuerpo de agua salobre situado en la costa oriental de México. Medimos parámetros de calidad del agua (oxígeno disuelto, salinidad, pH, temperatura del agua, materia orgánica en los sedimentos y demanda química de oxígeno) y muestreamos la macrofauna bentónica en tres momentos del año que difieren en sus condiciones climáticas (estaciones fría, seca y de lluvias). Dado el pequeño tamaño de la mayoría de los individuos en las muestras de macrofauna bentónica, se utilizó el volumen del cuerpo, en lugar de peso, para estimar su tamaño corporal. Las relaciones tamaño corporalabundancia de ambos grupos taxonómicos fueron descritas ordenando los datos de cada estación en clases de tamaño corporal cuya amplitud estaba establecida por una escala logarítmica de base 2. En ambos grupos taxonómicos, las frecuencias observadas por clase de tamaño corporal en cada estación se estandarizaron a densidades de captura (es decir, individuos/m3). Análisis de regresión no-lineal se realizaron separadamente para cada grupo taxonómico en cada estación del año para evaluar si los espectros de tamaño corporal seguían funciones escalares de potencia. Además, para cada grupo taxonómico, se utilizaron análisis de regresión múltiple para determinar si estas relaciones variaban entre estaciones. Nuestros resultados indicaron que, mientras las relaciones tamaño corporal-abundancia en ambos grupos taxonómicos siguieron funciones potenciales, los parámetros que definen la forma de estas relaciones variaron entre estaciones. Estas variaciones en los parámetros de las relaciones tamaño corporal-abundancia parecen estar relacionadas con cambios en la abundancia de los individuos dentro de las diferentes clases de tamaño corporal, que parece seguir los cambios estacionales que se producen en las condiciones ambientales de la laguna. Por lo tanto, proponemos que estas relaciones tamaño corporalabundancia se ven influidas por la frecuencia e intensidad de los cambios ambientales que afectan este ecosistema.

Abundancia y diversidad larval de gasterópodos en el Caribe Mexicano en relación con la temperatura, la salinidad y el oxígeno disuelto / Abundance and larval diversity of gastropods in the Mexican Caribbean in relation with temperature, salinity and dissolve oxygen

Quintana Roo has over 500 species of gastropods but little is known of the larval stages. We sampled four sites monthly from January to December 2008 with plankton tows in triplicate and a conical net of 300μm mesh. Puerto Morelos had the highest records (41.26±63.23 larvae•10m-3), followed by Mahahual (14.78±28.21 larvae•10m-3); Sian Ka’an and Xel-Ha had the lowest densities (9.16±16.73 and 3.35±4.33 larvae•10m-3, respectively). May and August had the highest records (33.66±67.39 and 31.78±25.92 larvae•10m-3, respectively), March and December the lowest (1.70±1.88 and 3.18±5.27 larvae•10m-3, respectively). There were differences in the spatial mean density (p <0.0001) and time (p= 0.0275). We identified 33 species, genera Strombus, Natica, Cerithium, Nassarius, Neritidae, Cerithiopsis, Nannodiela, Rissoina, Bulla, Bittium, Modulus and Prunum, of which 28 species were recorded in Puerto Morelos. Natica, Epithonium and Cerithium had the highest incidence in the four locations.

Quintana Roo tiene mas de 500 especies de gasterópodos pero muy poco se conoce de los estadios larvales. Muestreamos cuatro sitios mensualmente de enero a diciembre de 2008 con arrastres de plancton por triplicado y con una red cónica con malla de 300μm. Puerto Morelos tuvo los mayores registros (41.26±63.23 larvas•10m-3), seguido por Mahahual (14.78±28.21 larvas•10m-3), Sian Ka’an y Xel-Há presentaron las densidades menores (9.16±16.73 y 3.35±4.33 larvas•10m-3, respectivamente). Mayo y agosto presentaron los mayores registros (33.66±67.39 y 31.78±25.92 larvas•10m-3, respectivamente), marzo y diciembre los menores (1.70±1.88 y 3.18±5.27 larvas•10 m-3 respectivamente). Se registraron diferencias significativas en la densidad media espacial (p:<0.0001) y temporal (p: 0.0275). Identificamos un total de 33 especies de gasterópodos de los géneros Strombus, Natica, Cerithium, Nassarius, Neritidae, Cerithiopsis, Nannodiela, Rissoina, Bulla, Bittium, Modulus y Prunum, de las cuales 28 especies se registraron en Puerto Morelos. Natica, Epithonium y Cerithium fueron los géneros con mayor incidencia en las cuatro localidades.

Eco-etología básica del caracol rosa Strombus gigas (Mesogastropoda: Strombidae), en Xel-Há, Yucatán, Caribe mexicano / Basic eco-ethology of the queen conch, Strombus gigas (Mesogastropoda: Strombidae) in Xel-Há, Yucatán, Mexican Caribbean

The queen conch Strombus gigas is an important fishery in the Caribbean, whose populations are currently overexploited. Since the decade of 1980 there have been several studies on aquaculture, resource management and area rehabilitation. However, little is known about its behavior in a natural environment and the influence of environmental parameters. Monthly surveys, from January to November 2012 were conducted in in Xel Ha, to observe and quantify six behaviors of S. gigas: rest, feeding, movement, burying, copulation and spawning. The observations were made every hour from 8h to 17h by free diving through three transects with three replicates each. Each behavior was observed 90 times each month. Salinity, temperature and dissolved oxygen were registered at the bottom. We found the highest number of snails at rest in July and the lowest in March and September. Feeding and movements had a peak in August. Most buried in October and November. Copulation was first observed on March with a peak in June and July to October’s spawning. In daytime observations restingt had a peak at 8h; feeding and moving at 12 to 17h. Copulation and spawning did not have a clear pattern. Variations between months and hours (resting, feeding, moving and buried) were significant (p<0.05). Resting correlated with temperature and being buried with oxygen level (r=-0.5803; p=0.0536). Feeding and moving correlated with temperature and salinity. These results should be useful for the conservation, restoration and aquaculture programs. Rev. Biol. Trop. 62 (Suppl. 3): 215-222. Epub 2014 September 01.

El caracol rosa Strombus gigas tiene importancia pesquera en el Caribe, cuyas poblaciones se encuentran sobreexplotadas. Desde la década de 1980 se han desarrollado estudios de acuacultura, manejo del recurso y rehabilitación de áreas con la finalidad de proteger e incrementar sus poblaciones. Sin embargo, poco se sabe sobre el comportamiento del caracol rosa en su medio natural y la influencia de los parámetros ambientales. Mensualmente de enero a noviembre de 2012 en la caleta de Xel Há se observaron y cuantificaron seis comportamientos de S. gigas: reposo, alimentación, movimiento, cópula, enterrados y desove. Las observaciones se realizaron cada hora de 8h a 17h por medio de buceo libre en tres transectos con tres repeticiones cada uno. Cada comportamiento fue observado 90 veces cada mes. Se registraron datos de salinidad, temperatura y oxígeno disuelto en el fondo. El comportamiento anual de S. gigas presentó el mayor número de caracoles en reposo en julio. La alimentación y el movimiento tuvieron un máximo en agosto. La mayoría de caracoles enterrados se encontró en octubre y noviembre. La cópula comenzó a observarse en marzo con un máximo en junio y el desove de julio a octubre. En las observaciones diurnas e independientemente de los meses, el reposo tuvo un pico a las 8h, alimentación a las 12 y movimiento a las 17h. La cópula y el desove no presentaron un patrón en su comportamiento. Existieron variaciones significativas entre meses y horas (reposo, alimentación, movimiento y enterrado) (p<0.05). El reposo se correlacionó con la temperatura y los enterrados con el oxígeno (r=-0.5803; p=0.0536). La alimentación con temperatura, salinidad y oxígeno. El movimiento con temperatura y salinidad. Estos resultados son útiles para programas de conservación, restauración y cultivo de la especie.

Estudio histológico del tubo digestivo y aparato venenoso de Gemmula periscelida (Gastropoda: Turridae) / Histologic study of digestive tract and venom apparatus of Gemmula periscelida (Gastropoda: Turridae)

En el presente trabajo se describe anatómica e histológicamente el tubo digestivo y aparato venenoso de Gemmula periscelida (Gastropoda: Turridae) en ejemplares colectados al Noroeste de la Plataforma Continental Yucateca. Se determinó que el tipo de epitelio que reviste a cada una de las zonas del tubo digestivo (probóscide, esófago anterior, medio y posterior, estómago, glándula digestiva e intestino) y al aparato venenoso, es diferente a lo reportado para otros túrridos; por lo que se infiere el posible mecanismo de alimentación para esta especie.

In this paper we realized anatomical and histologically description of the digestive tract and venom apparatus of Gemmula periscelida (Gastropoda: Turridae) specimens collected northwest of the Yucatan Shelf. Results of analysis show that there are differences in the type of epithelium coating each of the areas of the digestive tract (proboscis, anterior, middle and posterior esophagus, stomach, digestive gland and intestine) and of a venom apparatus with respect to that reported for other turrid snails. This suggests the possible feeding mechanism for this species.

Morfologia Comparada de Asolene meta (Ihering, 1915) e Asolene spixii (d´Orbigny, 1838) (Caenogastropoda: Ampullariidae) / Comparative morphology of asolene meta (Ihering,1915) and asolene spixii (d'Orbigny, 1838) (Caenosgastropoda: ampullariidae)

Ampulariideos são gastrópodes límnicos que habitam as regiões tropicais e subtropicais das Américas, da África e da Ásia. Geralmente são os principais constituintes de ecossistemas límnicos e têm importante papel na cadeia trófica. A anatomia da maioria dos ampulariideos é pobremente conhecida e sua classificação é baseada principalmente em caracteres conquiliológicos, geralmente variáveis, resultando em uma confusa taxonomia. Dentre os quatro gêneros que ocorrem na América do Sul, Asolene é um dos menos estudados. Visando contribuir para a clarificação da taxonomia de Asolene meta e Asolene spixii, bem como fornecer dados adicionais para o entendimento das relações de parentesco dentro da família, foram estudados a morfologia e aspectos moleculares de espécimes coletados no Brasil, incluindo topótipos de A. meta. Asolene spixii ocorre no norte da Argentina, Uruguai, Paraguai e sul do Brasil, enquanto A. meta é endêmica da bacia do rio São FranciscoAs conchas de ambas as espécies são similares, mas a abertura de A. meta é arredondada e em A. spixii é mais alongada. As análises estatísticas (Teste t de Student e Análise Discriminante) revelaram que as variáveis conquiliométricas são significativamente diferentes entre as espécies, sendo a altura da abertura a que mais contribui para a discriminação entre A. meta e A. spixii. A microscopia eletrônica de varredura da rádula não revelou diferenças interespecíficas. A anatomia do estômago é similar em A. meta e A. spixii, no entanto o escudo gástrico de A. meta é mais desenvolvido. A anatomia externa, cavidade do manto e sistema nervoso seguem o mesmo padrão dos demais ampulariideos. As principais diferenças anatômicas encontram-se nos caracteres do rim e da bainha do pênis. O rim anterior de A. meta é alongado e maior que em A. spixii, que é triangular...

Ampullariidae are freshwater snails inhabiting tropical and subtropical regions in Asia, Africa and the Americas. They are often major constituents of freshwater ecosystems and play important roles in food webs. The detailed morphology of mostampullariids is poorly known and their classification is based primarily on oftenvariable shell characters, resulting in taxonomic confusion. Among the four genera in South America, Asolene is one of the least studied. To clarify the taxonomy of Asolene meta and Asolene spixii and provide additional data to understand systematic relationships within the family we assessed morphological and moleculardata from specimens collected in Brazil, including the type locality of A. meta. A.spixii occurs in northern Argentina, Uruguay, Paraguay and southern Brazil while A. meta is endemic to the basin of São Francisco river. The shells are similar in both species but the aperture of A. meta is rounded and in A. spixii it is more elongated. Statistical analysis (Test t and Discriminant Analysis) showed that the conquiliologicalvariables are significantly different between the species and the aperture height contributes most to the discrimination between A. meta and A. spixii. The scanning electron microscopy didn´t reveal interspecific variations. The stomach are similar inA. meta and A. spixii, although the gastric shield in A. meta is more developed. The external anatomy, mantle cavity and nervous system are the same as in ampullariids. There are a few anatomical differences, primarily in the characters of the kidney andthe penial sheath. The elongated anterior kidney in A. meta is larger than that of A. spixii, which is triangular...

One case of triphallia in the marine snail Echinolittorina peruviana (Caenogastropoda: Littorinidae) / Un caso de trifalia en el caracol marino Echinolittorina peruviana (Caenogastropoda: Littorinidae)

Gonochoric representatives of Littorinidae have a reproductive system organized with transit organs that connects the testicle with a penis specialized for internal fertilization. However, malformations at this level can produce, like triphallia (presence of triple penis). This description corresponds to one case of triphallia found in Echinolittorina peruviana (Lamarck, 1822) inhabitant of the South Pacific coasts. The macro and microscopic analysis reveals that every penis is an independent appendix whose individual morphology is similar to that in normal individuals, characterized by a non pigmented conic penis associated with a mammilliform gland located at the base of the right ocular tentacle. The cervical sperm groove lined by a simple ciliated and secretory columnar epithelium, runs along the neck of the animal, is subdivided into the base of each penis forming the penile seminal groove in each of them, and ascends dorsally from the base to the tip. The other organs that make up the reproductive system have a normal organization (no duplication or triplets), and the testicle organized in acini contains all the cell types of the male germ line. Although the cause of this condition is still unknown, might be associated with genetic causes and not of environmental kind...

Los representantes gonocóricos de Littorinidae presentan un sistema reproductor organizado con órganos de tránsito que conectan al testículo con un pene especializado para la fecundación interna. Sin embargo, pueden ocurrir malformaciones a este nivel, como la trifalia (presencia de pene triple). Esta descripción corresponde a un caso de trifalia encontrado en el representante gonocórico Echinolittorina peruviana (Lamarck, 1822), habitante de las costas del Pacífico Sur. El análisis macro y microscópico revela que cada pene es un apéndice independiente cuya morfología individual es semejante a la de individuos normales, caracterizada por un pene de forma cónica no pigmentado asociado a una glándula de tipo mamiliforme ubicada en la base del tentáculo ocular derecho. El surco espermático cervical revestido por un epitelio simple cilíndrico ciliado y secretor, recorre el cuello del animal, se subdivide en la base de cada pene conformando el surco espermático peneano en cada uno de ellos, y asciende dorsalmente desde la base hasta el ápice. Los otros órganos que conforman el sistema reproductor poseen una organización normal (sin duplicaciones o triplicaciones), y el testículo organizado en acinos contiene todos los tipos celulares de la línea germinal masculina. Aunque aún la causa de esta patología es desconocida podría estar asociada a causas genéticas y no de tipo ambiental...

A new species of Urocopitid land snail from Haiti and a discussion of the genus Autocoptis (Gastropoda: Urocoptidae)

Autocoptis paulsoni n. sp. is described from Haiti. it is characterized by its large size, its cylindricaltapered shape, its fine costate sculpture on the teleoconch, a distinct but weak circum basal keel and its abbreviate conical juvenile shell. it is most similar to Autocoptis gruneri (Dunker 1844), which is redescribed, and its distribution is reviewed. The taxonomic status of the genus Autocoptis Pilsbry 1902 and its subgenus Urocoptola Clench, 1 935 are reviewed. The genus is endemic to Hispaniola and satellite islands.

Para Haití se describe Autocoptis paulsoni n. sp. Esta especie se caracteriza por su gran tamaño, su forma cilíndrica-cónica, teleoconcha en forma de costillas, una clara pero débil quilla circumbasal y concha juvenil cónica y abreviada. Es muy similar a Autocoptis gruneri (Dunker, 1844), que se describe de nuevo y su distribución se revisa. También se presenta el estado taxonómico del género Autocoptis y del subgénero Urocoptola. El género es endémico de La Española y las islas satélites.

Comparación de la abundancia, estructura de tallas y fecundidad de Voluta musica (Caenogastropoda: Volutidae) en tres sitios de la costa norte de la Península de Araya, Venezuela / Abundance, size structure and fecundity of Voluta musica (Caenogastropoda: Volutidae) in three sites of the north coast of Araya Peninsula, Venezuela

Abundance, size structure and fecundity of Voluta musica (Caenogastropoda: Volutidae) in three sites of the north coast of Araya Peninsula, Venezuela. Considering the intensive artisanal fishing activity and the consequent carrion discard found at Isla Caribe, in relation to other two sites with no intensive artisanal fishing activity, we expect different effects on some features of V. musica life history (larger egg capsules, larger organisms, higher abundance of adult organisms). In this paper we compare some population parameters of Voluta musica at three localities in the north coast of the Araya Peninsula in Venezuela under different fishing exploitation regimes. The samples were taken monthly during 2008 and 2009 at Isla Caribe, Isla Lobos and Bajo Cuspe. At each site, samples were taken within three areas of 40m². The abundance of V. musica ranged between 5 ind/120m² to 30 ind/120m² with significant differences between sites (F=7.77; p<0,01). Organisms from Isla Caribe were larger in size (p=0,045), than those in the other two sites. There is a significant differences in the number of egg capsules between sites and between months, and there is clear evidence that Isla Caribe has the largest abundance of egg capsules (p<0,01) suggesting that the extra feeding source (carrion) found at Isla Caribe could have a positive effect on the reproductive potential of the V. musica population at this site.

Teniendo en cuenta la intensa actividad pesquera artesanal y subsecuente fuente adicional de alimento como carroña en Isla Caribe, se esperaría un efecto sobre algunos parámetros poblacionales de V. musica como: mayor número de ovicápsulas, individuos de tallas mayores y densidades de caracoles adultos mayores. Con el presente trabajo se desea conocer la abundancia, estructura de talla y fecundidad de Voluta musica en tres sitios de la costa norte de la Península de Araya en las que existen actividades de pesca diferenciales. Se realizaron muestreos mensuales entre 2008 y 2009 en Isla Caribe, Isla Lobos y Bajo Cuspe, en cada uno con 3 áreas de 40m². La abundancia varió de 5ind/120m² a 30ind/120m², con diferencias significativas entre los sitios (F= .77; p<0,01), siendo igual para Bajo Cuspe e Isla Caribe (p=0,39) pero distinta y menor en Isla Lobos, (p=0,008; 0,0149). Los individuos de Isla Caribe demostraron ser más grandes (p=0,045). Existen diferencias significativas entre sitios y entre meses en el número de ovicápsulas (p<0,01), siendo Isla Caribe el sitio con mayor abundancia de ovicápsulas (p<0,01). Esto sugiere que el alimento suplementario en forma de carroña podría incrementar el potencial reproductivo de la población en Isla Caribe.

Growth and population assessment of the queen conch Strombus gigas (Mesogastropoda: Strombidae) by capture mark-recapture sampling in a natural protected area of the Mexican Caribbean / Evaluación del crecimiento y población del caracol rosado Strombus gigas (Mesogastropoda: Strombidae) mediante muestreo de marcaje-recaptura en un área natural protegida del Caribe mexicano

The Inlet of Xel-Ha is used as a park for ecotourism, representing a sanctuary for the conservation of Pink Queen Conch. Increasing fishing pressure has led to the inclusion of the species in CITES. Most knowledge about the growth of the queen conch was generated through aquaculture, ocean enclosures or obtained using estimates derived from population dynamics. In this study we estimated the growth rate of juvenile S. gigas in a natural protected area by direct methods, during the period of April 2009 to January 2011. Data was obtained by capture-mark-recapture sampling. 1418 individuals were tagged and growth of 714 conchs was analyzed. Population size and density was estimated using Schnabel’s method. The average density was estimated at 0.1694 ± 0.0996ind. m-2, while the highest density was estimated for September 2010 (0.3074ind. m-2). The highest growth rate (0.27 ± 0.10mm day-1) was detected in juveniles with an initial size between 100-149mm, followed by conch <100mm, with an increase of 0.24 ± 0.05mm day-1. The growth rate decreased for individuals with an initial size between 150-199mm (0.18 ± 0.09mm day-1) and for organisms > 200mm (0.08 ± 0.07mm day-1). Variability in growth rate was high in conch 100-149mm and showed seasonal differences, with the highest growth rate in May 2010. Recruitment of juveniles was highest in October 2009 and February 2010. The population of Xel-Ha has grown in size and more large and juvenile conch could be found than in previous studies, indicating that Xel-ha park is working as a sanctuary for the conservation of the queen conch in Mexico’s Riviera Maya. The growth rate of juvenile conch in Xel-Ha is high and exhibits large variations in individuals, reflecting the natural conditions of foraging and aggregation. Seasonal differences in growth rate may be associated with water quality and availability of nutrients for primary production. We conclude that the direct method is useful for the assessment of growth in juvenile S. gigas and that growth in natural conditions may be higher than in aquaculture systems. This information may be applied to fishery management as well as rehabilitation programs and aquaculture.

La Ensenada de Xel-Ha es usada como parque para ecoturismo y representa un santuario para la conservación del caracol rosado. El incremento en la presión de la pesca ha llevado a la inclusión de esta especie en CITES. Mucho del conocimiento acerca del crecimiento del caracol rosado ha sido generado a través de la acuicultura, encierros oceánicos o usando estimaciones derivadas de las dinámicas poblacionales. En este estudio estimamos la tasa de crecimiento de Strombus gigas juvenil en un área natural protegida, por métodos directos durante el período de abril 2009 a enero 2011. Los datos fueron obtenidos por muestras de captura-marca-recaptura. Un total de 1 418 individuos fueron marcados y el crecimiento de 714 caracoles fue analizado. La talla de la población y la densidad relativa fue estimada usando el método de Schnabel. La densidad promedio relativa fue estimada en 0.1694±0.0996ind. m-2, mientras que la densidad más alta fue estimada para septiembre 2010 con 0.3074ind. m-2. La tasa de crecimiento más alta (0.27±0.10mm día-1) fue detectada en juveniles con una talla inicial entre 100-149mm, seguida por juveniles <100mm, con un incremento de 0.24±0.05mm día-1. La tasa de crecimiento disminuyó para individuos con una talla inicial entre 150-199mm (0.18±0.09mm día-1) y para organismos >200mm (0.08 ± 0.07mm día-1). La variabilidad en la tasas de crecimiento fue alta en individuos entre 100-149mm y mostró diferencias estacionales; con la tasa de crecimiento más alta en mayo 2010. El reclutamiento de juveniles más alto se dio en octubre 2009 y en febrero 2010. La población de Xel-Ha ha crecido en tamaño y se pudo encontrar más adultos y juveniles que en estudios anteriores, lo que demuestra que el Parque de Xel-Há está funcionando como un santuario para la conservación del caracol rosado del Caribe en la Riviera Maya de México. La tasa de crecimiento de juveniles en Xel-Ha es alta y presenta grandes variaciones en los individuos, lo ...

Abundancia y distribución de larvas de Strombus gigas (Mesogastropoda: Strombidae) durante el período reproductivo de la especie en el Caribe Mexicano / Abundance and distribution of Strombus gigas (Mesogastropoda: Strombidae) larvae during their reproductive period in the Mexican Caribbean

Abundance and distribution of Strombus gigas (Mesogastropoda: Strombidae) larvae during their reproductive period in the Mexican Caribbean. The Queen Conch (Strombus gigas Linnaeus, 1758) is a species of economic importance in the Caribbean Sea, which, in the 1980’s represented the second fishery after de spiny lobster, reason that is currently in a state of overfishing. In order to determine the larval abundance variation during the reproductive season, four locations of the Mexican Caribbean “MC” (Mexico: Puerto Morelos, Sian Ka’an, Mahahual; Belize: San Pedro) were sampled. Monthly, from May to October 2008, planktonic net drags (300μm) were carried out at each location. Temperature (°C), salinity (ppm) and dissolved oxygen (mg L-1) were recorded for each site. A mean larval density of 0.34±0.87 (larvae 10 m-3) was registered between locations, with a peak in August and September (0.82±1.00 and 0.76±1.68 larvae 10m-3, respectively). The larval density was 60% correlated with salinity (r=0.6063, p<0.05). A one-way ANOVA showed significant statistical larval density in time (p<0.05) and space (p<0.05), where Puerto Morelos displayed the higher records during the study (0.54±1.49 larvae 10m-3). An average larval size of 332.44±59.66µm was recorded. Larval sizes differed significantly between locations (p<0.05), but not considering months (p>0.05). A 100% of the captured larvae correspond to stage I, showing local reproductive activity, that might indicate the sampled sites in the MC are a source of larvae to S. gigas. Rev. Biol. Trop. 60 (Suppl. 1): 89-97. Epub 2012 March 01.

El caracol rosa (Strombus gigas, Linnaeus, 1758) es una especie de importancia económica en el Mar Caribe, por lo cual, en la década de 1980 representó la segunda pesquería después de la langosta espinosa, razón por la que actualmente se encuentra en estado de sobrepesca. Con el objetivo de determinar la variación en la abundancia de larvas durante la época reproductiva, cuatro localidades del Caribe Mexicano “CM” (México: Puerto Morelos, Sian Ka’an, Mahahual; Belice: San Pedro) fueron muestreadas. Mensualmente, de mayo a octubre del 2008, se realizaron arrastres de plancton en cada localidad empleando una red cónica (300μm). Temperatura (°C), salinidad (ppm) y oxígeno disuelto (mg L-1) fueron registrados para cada sitio. Una densidad media larval de 0.34±0.87 larvas•10m-3 fue registrada entre localidades, con un pico de abundancia entre agosto y septiembre (0.82±1.00 y 0.76±1.68 larvas 10m-3, respectivamente). La densidad larval tuvo una correlación del 60% con la salinidad (r=0.6063, p<0.05). El ANOVA de una vía mostró significancia estadística en tiempo (p<0.05) y espacio (p<0.05), donde Puerto Morelos tuvo los mayores registros durante el estudio (0.54±1.49 larvas 10m-3). Fue registrada una talla media de 332.44±59.66µm. Las tallas variaron significativamente entre localidades (p<0.05), pero no entre meses (p>0.05). El 100% de las larvas capturadas corresponden al estadio I definido por Davis et al (1993), mostrando actividad reproductiva local, de esta manera, se considera que los sitios muestreados en el CM son fuente de larvas para la especie S. gigas.

Sperm morphology and natural biomolecules from marine snail Telescopium telescopium: a phylogenetic perspective / Morfología de los espematozoides y biomoléculas naturales del caracol marino Telescopium telescopium: una perspectiva filogenética

Biochemical analysis of the cytosol fraction isolated from the ovotestis/spermatheca glands of marine mollusc Telescopium telescopium and it's sperm microtubular structure revealed that relatively similar biomolecules like different enzymes, hormones, minerals and structures of the sperm are also exist in humans. Moreover, antiserum of the cytosol fraction was found to cross-react with the human sperm antigen indicated presence of a common sperm surface antigenicity between these two diversified species. These findings might support and / or hypothesize about the origin and diversification of the vertebrate molecules from its ancestral form (s) from the invertebrates, and basic physiological functions of these ancestral biomolecules including some of the cellular structures plausibly remain the same regardless their structural changes even after evolution.

El análisis bioquímico de la fracción aislada del citosol desde las glándulas ovotestes/espermateca del molusco marino Telescopium telescopium y su estructura tubular espermática revelaron biomoléculas relativamente similares como tales como diferentes enzimas, hormonas, minerales y estructuras de los espermatozoides que también existen en los seres humanos. Por otra parte, en el antisuero de la fracción citosólica se encontró una reacción cruzada con los antígenos del esperma humano indicando la presencia de una superficie espermática de antigenicidad común entre estas dos diversificadas especies. Estos hallazgos pueden apoyar y/o hipotetizar sobre el origen y la diversificación de las moléculas de los vertebrados desde su forma (s) ancestral desde los invertebrados, y funciones básicas fisiológicas de estas biomoléculas ancestrales incluyendo algunas de las estructuras celulares siendo plausiblemente las mismas, independientemente de sus cambios estructurales incluso después de la evolución.

Four species of land snails from Costa Rica and Panama (Pulmonata: Spiraxidae)

Four species of land snails are described from Costa Rica and Panama. Two are new species and two have remained poorly known since their first discovery. A fifth species from Mexico and Guatemala is illustrated for comparative purposes because it has not been figured since 1877, and previous figures of it are inadequate for comparative purposes. The Spiraxidae subfamilies and the piraxinae genera are redefined. Rev. Biol. Trop. 58 (1): 195-202. Epub 2010 March 01.

Se describen cuatro especies de caracoles terrestres de Costa Rica y Panamá. Dos son especies nuevas y dos han permanecido poco conocidas desde su descubrimiento. Se ilustra en detalle una quinta especie de México y Guatemala, para efectos comparativos, ya que no se había ilustrado desde 1877, y sus descripciones previas no son adecuadas para una comparación. Se redefinen las subfamilias pertenecientes a Spiraxidae y el género Spiraxinae.

Daños por depredación y tamaño de concha del caracol diádromo Neritina virginea (Gastropoda: Neritidae) en el Río Mameyes, Puerto Rico

Predator damage and shell size on the diadromous snail Neritina virginea (Gastropoda: Neritidae) in the Mameyes River, Puerto Rico. We compared predators’ damage with shell size in live individuals and empty shells (n=5066) of the snail Neritina virginea in the Mameyes River (Puerto Rico, Greater Antilles). According to the literature and direct observations, damages on empty shells were attributed to predation by aquatic birds (e.g. Gallinula chloropus) and decapods (e.g. Macrobrachium spp.), while damages on live individuals were due to rasping by co-specifics and erosion. Predation by decapods and birds, as estimated by the proportion of empty shells, was low (2 and 0.36%, respectively). Shell size was significantly different between types of predators (range: decapods: 3.5-15.0mm, birds: 8.1-19.4mm). By comparing sizes of the empty shells and the live individuals, we concluded that decapods specialize on large groups of small migratory juveniles, while birds specialize on the largest resident individuals. Worn shells were highly frequent in both empty shells and live individuals, and sizes did not differ between samples. A comparison by slow-flow and fast-flow habitats showed that predators do not discriminate shell sizes between environments. However, the frequency of damage by birds and decapods was greater under slow-flow conditions. Despite of the little contribution of predation to the population dynamics in this species, predation might be an important driver of size-dependent behavioral responses such as upstream migration and microhabitat selection. Rev. Biol. Trop. 57 (4): 1069-1080. Epub 2009 December 01.

Se compararon las abundancias y tamaños de conchas del gasterópodo Neritina virginea de acuerdo a los daños presentados en especimenes vivos y muertos (n= 5066) recolectados en el río Mameyes, Puerto Rico (Antillas Mayores). Se observaron daños por depredación de aves y camarones, y signos de erosión por la acción del raspado de la rádula por parte de otros individuos de la misma especie. La depredación fue aparentemente baja (<2.5%), pero los tamaños de concha depredados por aves y camarones fueron significativamente diferentes. Las primeras se especializan en los individuos residentes más grandes, mientras que los segundos se especializan en individuos juveniles que presentan un comportamiento migratorio. Estos tamaños no fueron diferentes entre dos hábitats, aunque se observó más conchas depredadas por decápodos que por aves. El desgaste fue común en conchas de todos los tamaños. A pesar de su baja contribución a la dinámica poblacional de los gasterópodos, la depredación podría ser un control importante de respuestas de comportamiento dependientes del tamaño, tales como la migración río arriba y la selección de microhábitats.

Do climate variables and human density affect Achatina fulica (Bowditch) (Gastropoda: Pulmonata) shell length, total weight and condition factor? / Variáveis ambientais e humanas afetam o comprimento da concha, peso total e fator de condição de Achatina fulica (Gastropoda: Pulmonata)?

The length-weight relationship and condition factor have been broadly investigated in snails to obtain the index of physical condition of populations and evaluate habitat quality. Herein, our goal was to describe the best predictors that explain Achatina fulica biometrical parameters and well being in a recently introduced population. From November 2001 to November 2002, monthly snail samples were collected in Lauro de Freitas City, Bahia, Brazil. Shell length and total weight were measured in the laboratory and the potential curve and condition factor were calculated. Five environmental variables were considered: temperature range, mean temperature, humidity, precipitation and human density. Multiple regressions were used to generate models including multiple predictors, via model selection approach, and then ranked with AIC criteria. Partial regressions were used to obtain the separated coefficients of determination of climate and human density models. A total of 1.460 individuals were collected, presenting a shell length range between 4.8 to 102.5 mm (mean: 42.18 mm). The relationship between total length and total weight revealed that Achatina fulica presented a negative allometric growth. Simple regression indicated that humidity has a significant influence on A. fulica total length and weight. Temperature range was the main variable that influenced the condition factor. Multiple regressions showed that climatic and human variables explain a small proportion of the variance in shell length and total weight, but may explain up to 55.7 percent of the condition factor variance. Consequently, we believe that the well being and biometric parameters of A. fulica can be influenced by climatic and human density factors.

A relação peso comprimento e o fator de condição têm sido bastante explorados em pesquisas envolvendo caracóis para obter o índice de condição física em populações e avaliar a condição do habitat. Neste trabalho, nosso objetivo foi descrever que variáveis influenciam os parâmteros biométricos e o bem estar de Achatina fulica em uma recente introdução. De novembro de 2001 a novembro de 2002, amostras mensais desses caracóis foram coletadas na cidade de Lauro de Freitas (Bahia), Brasil. Em seguida, os caracóis foram acondicionados em laboratório e foram obtidos o tamanho da concha e o seu peso. A partir desses dados a curva potencial e o fator de condição foram calculados. Cinco variáveis ambientais foram consideradas: amplitude de temperatura, temperatura média, humidade, precipitação e densidade humana. Regressões múltiplas foram usadas para gerar modelos preditivos através do critério de seleção e logo foram ordenados utilizando o critério de Akaíke. Regressões parciais foram usadas para obter os coeficientes de determinação do clima e fatores humanos. Um total de 1460 indivíduos foram coletados, apresentando uma amplitude de crescimento de concha entre 4,9 a 102,5 mm (média 42,18 mm). A relação entre o crescimento total e o peso revelou que A. fulica apresentou um crescimento alométrico negativo. Regressões simples indicaram que a umidade teve uma influencia significativa sobre o tamanho total e o peso. A amplitude de temperatura foi a variável que mais influenciou o fator de condição. Os modelos de regressão múltipla indicaram que os fatores climáticos e humanos explicaram uma pequena porção da variança, no entanto explicou 55,8 por cento da variância do fator de condição. Consequentemente, acreditamos que o bem estar e os parâmetros biométricos de A. Fulica podem ser influenciados por fatores climáticos e humanos.

Microscopic anatomy of the male reproductive system in Echinolittorina peruviana (Mollusca: Caenogastropoda) / Anatomía microscópica del sistema reproductor masculino de Echinolittorina peruviana (Mollusca: Caenogastropoda)

Echinolittorina peruviana (Lamarck, 1822), a gonochoric representative of the Littorinidae on the SE Pacific coast, has a male reproductive system adapted for internal fertilization. We describe this system at both macro- and microscopic levels, particularly the compartmentalized organization of the gonad, and the morphology of the penis. The male reproductive system has a variegated conical gonad-digestive gland complex. The gonad presents three compartments, 1) gametogenic acinar among the glandular acini, 2) periacinar with a layer of fusiform somatic cells and, 3) interacinar with glycogen storage cells shared with glandular acini. Spermatogenesis occurs within the acinar gametogenic compartment, with the germinal line organized in centripetal form towards the lumen. The seminal vesicle stores the products of spermatogenesis; in its cephalic region the euspermatozoa are united to the epithelium and the paraspermatozoa are distributed in the lumen. A short duct connects the seminal vesicle to the prostate gland that is open to the pallial cavity over its entire length. The anterior zone of the prostate gland is joined to the cervical spermatic groove that runs along the neck of the snail through the right pallial region; this continues as the penile spermatic groove, ascending from the base to the point of the penis. The penis is acutely conical and unpigmented; towards the anterior and adjacent to its base there is a glandular complex with a mamilliform process and a discoidal glandular region. The secretion from the discoidal region is transformed in a spicule of unknown function, whose histology is described here for the first time. The mamilliform process is formed by the spicular projection and a connective-muscle tissue band which surrounds it and separates it from the discoidal follicular glandular region; the follicular secretion crosses this band and is incorporated into the epithelium which lines the interior of the process.

Echinolittorina peruviana (Lamarck, 1822), representante gonocórico de Littorinidae en el Pacífico Sur, tiene un sistema reproductor masculino adaptado para la fecundación interna, que en este estudio se describe a niveles macrocoscópico y microscópico; enfatizando la organización compartimentalizada de la gónada y la morfología del pene. El sistema reproductor masculino se presenta como un complejo cónico gónada-glándula digestiva abigarrado. La gónada presenta tres compartimientos: 1) gametogénico acinar entre los acinos glandulares, 2) periacinar con una capa de células somáticas fusiformes y 3) interacinar con células almacenadoras de glicógeno, compartido con los acinos glandulares. En el compartimiento gametogénico acinar ocurre la espermatogénesis con la línea germinal organizada en forma centrípeta hacia el lumen. Hacia anterior, la vesícula seminal almacena los productos de la espermatogénesis; en su región cefálica los euespermatozoides se unen al epitelio y los paraespermatozoides se distribuyen en el lumen. Este órgano se conecta con un conducto corto a la glándula prostática, abierta hacia la cavidad paleal en toda su longitud. La zona anterior de la glándula prostática se une al surco espermático cervical, que recorre el cuello del animal por la región paleal derecha; éste continúa como surco espermático peniano ascendiendo desde su base hasta la punta. El pene es cónico aguzado no pigmentado; hacia anterior adyacente a su base, hay un complejo glandular con un proceso mamiliforme y una región glandular discoidal. Su producto de secreción sería una espícula de función desconocida, cuya histología es descrita por primera vez. En este complejo glandular, el proceso mamiliforme está constituido por la proyección espicular y una banda conjuntivo-muscular que lo rodea y separa de la región glandular folicular discoidal; su secreción atraviesa dicha banda, incorporándose al epitelio de revestimiento interno del proceso.

The population density effects on the reproductive biology of the snail Bradybaena similaris (Férussac, 1821) (Mollusca, Gastropoda) / Efeitos da densidade populacional na biologia reprodutiva do molusco Bradybaena similaris (Molusca, Gastropoda)

The influence of population density on some aspects of the reproductive biology of the snail Bradybaena similaris was studied. Molluscs were maintained under 0.2 (isolated), 0.3, 0.6, 1.0, 1.3 and 1.7 snail/m² densities. The animals maintained under 0.3 and 0.6 snail/m² showed the lowest numbers of eggs laid/snail, being the highest value observed to the 1.7 snail/m². The hatching of the snails maintained under 0.3 snail/m² density, begun at the 21st day after laying, and the maximum time required to the hatching was 36 days was observed to the eggs came from snails maintained under the densities 0.6, 1.0, 1.3 snail/m², respectively. The highest percentage hatchability (55.56 percent) was observed to isolated snails. The galactogen content in the albumen gland did not seem to accompany the alterations occurred in the reproduction of B. similaris in response to the different population densities.

A influência da densidade populacional em alguns aspectos da biologia reprodutiva do molusco Bradybaena similaris foi estudada. Os moluscos foram mantidos em densidades de 0.2 (isolados), 0.3, 0.6, 1.0,1.3 e 1.7 moluscos/m². Nas densidades de 0.3 e 0.6 moluscos/m², os moluscos apresentaram os menores números de ovos postos por molusco, sendo o maior valor observado para essa variável na densidade de 1.7 molusco/m². A eclosão dos moluscos mantidos a uma densidade de 0.3 molusco/m², iniciou-se aos 21 dias após a postura, sendo o tempo máximo necessário para a eclosão 36 dias para ovos oriundos de moluscos mantidos nas densidades de 0.6, 1.0, 1.3 moluscos/m². O maior percentual de eclosão (55.56 por cento) foi observado para os moluscos isolados. O conteúdo de galactogênio na glândula de albúmem parece não acompanhar as alterações na reprodução de B. similaris em resposta a diferentes densidades populacionais.

Effects of dietary calcium on growth and oviposition of the African land snail Limicolaria flammea (Pulmonata: Achatinidae)

In an attempt to elucidate the role of calcium in the life of the edible Achatinid snail, Limicolaria flammea (Miller) I investigated short and long term effects of calcium added to the food. The short term experiments lasted for 18, 30 and 32 weeks respectively, while the long term experiment to determine life time utilization of calcium carbonate lasted for 15 months. In the short term experiments, hatchlings were divided into densities of one, ten and 50 snails. In the 10 snail group, there was a positive correlation between calcium provision, body weight (t test, p < 0.01; r = 0.96, p < 0.0001) and shell length (t test, p < 0.01; r = 0.96, p < 0.00001). There was also a positive correlation between increase in shell length and availability of calcium in the 1 snail group (t test, p< 0.01; r = 0.99, p < 0.00001). In the 50-snail group, the correlation was positive for shell length of the snails (t test, p < 0.05; r = 0.99, p < 0.0001) and body weight (t-test, p < 0.05; r = 99, p < 0.00001). Mortality was very high in the snails deprived of calcium and they did not produce eggs. In the long term experiment, there were three feeding peaks in L. flammea. In the first feeding peak, amount of food and calcium ingested by the snails increased in the first three months of life. The second feeding peak occurred at six months of age, while the last occurred at 10 months of age. The amount of calcium ingested during the second peak decreased gradually in the 4th and 5th month. The amount of calcium ingested was lowest during the 3rd feeding peak. The period of highest weight gained by the snails was between the 1st and 6th month and then dropped at between six and 12 months of age which corresponds to the period of egg production. There were also three peaks of egg production; the first was between six and eight months (535 eggs), the second at between 10 and 11 months (350 eggs) and the third at 13 to 14 months (310 eggs) respectively.

Estudié el efecto de agregar calcio al alimento sobre el desarrollo del caracol pulmonado africano Limicolaria flammea (Müller). La cantidad de calcio tuvo una correlación positiva con el peso corporal (T de Student, p < 0.01; r = 0.96, p < 0.0001) y la longitud de concha (T de Student, p < 0.01; r = 0.96, p < 0.00001). Los caracoles que no recibieron calcio murieron en gran cantidad y no produjeron huevos. En un experimento a largo plazo, hubo picos de consumo del calcio y el mayor aumento de peso fue en los seis meses iniciales. Los picos de producción de huevos fueron entre los seis y los ocho meses (535 huevos), entre los diez y once meses (350 huevos) y en los meses 13 y 14 (310 huevos).

Demografía del caracol Plicopurpura pansa (Neotaenioglossa: Muricidae) y constitución de la comunidad malacológica asociada en Guerrero, México

Demography of the snail Plicopurpura pansa (Neotaenioglossa: Muricidae) and constitution of the associated mollusk community, in Guerrero, Mexico. We quarterly sampled the molluskan community of Playa Ventura, Guerrero, Mexico. Sample size (20 m² in 1m² units) was determined by the spatial distribution pattern of Plicopurpura pansa using a negative binomial distribution. The density of the P. pansa was 5.19 snails/m² and the sex ratio near 1:1. The average size was 20.10 mm (most females were 10.5 to 27.0 mm; most males 12.0 to 27.0 mm). Density was high and small sized dominated. Mean size varied with time. General mean weight was 1.79 g. Females weight varied more, maybe because of the reproductive cycle. Recruits were collected in five samplings. Most copulation activity was in March of 2001. The associated community includes 26 species of Gastropoda, five of Bivalvia and one of Polyplacophora, Brachidontes semilaevis being dominant. Rev. Biol. Trop. 55 (3-4): 867-878. Epub 2007 December, 28.

Estudiamos la demografía de Plicopurpura pansa en Playa Ventura, Guerrero, México, con base en muestreos trimestrales. Su densidad fue de 5.19 caracoles/m². La proporción sexual fue cercana al 1:1. La talla promedio fue de 20.10 mm. Las tallas mejor representadas en hembras fueron de 10.5 a 27.0 mm y en machos de 12.0 a 27.0 mm. La población es de alta densidad y mayor frecuencia de tallas pequeñas. Hubo diferencias entre las tallas promedio de cada muestreo, formándose dos grupos de medias para cada sexo. El peso promedio fue 1.79 g. Las hembras presentaron mayor variación en peso, lo cual podría estar relacionado con el ciclo reproductivo. Hubo reclutamiento en cinco fechas de recolección. El mayor número de cópulas se observaron en marzo de 2001. Se identificaron 26 especies de gasterópodos, siete de bivalvos y una de poliplacóforos. La especie con mayor dominancia fue Brachidontes semilaevis.