Biología de poblaciones de especies simpátricas de Caprella (Amphipoda: Caprellidae) en un bosque de algas tropicales

The population biology of the three sympatric species of caprellids (Caprella danilevskii, C. equilibra and C. scaura) associated with a Sargassum bed was studied in the northern coast of São Paulo state, Brazil. Samplings were carried out monthly from October 2010 to February 2012. In each month, 25 fronds of Sargassum were randomly collected through snorkelling. The caprellids were identified, counted, classified by sex and separated into size classes. Caprella danilevskii was the most abundant species, with 14939 specimens recorded. The body size of males was larger than that of females for C. danilevskii and C. equilibra, and the sex ratio was skewed toward males for all species. The size-frequency distribution was polymodal for C. danilevskii and C. scaura and bimodal for C. equilibra. Mature males of C. scaura and C. equilibra were recorded in all size classes. The last size classes (from 8.3–9.4 to 12.7–13.8 mm) were dominated by mature males. Mature and ovigerous females were more frequent in intermediate size classes. Significant temporal variations were recorded for the three species with higher densities in spring and summer that are related to higher algal biomass; but other environmental factors are certainly important for explaining caprellid density variation.Se estudió la biología poblacional de las tres especies simpátricas de caprélidos (Caprella danilevskii, C. equilibra y C. scaura) asociadas a un lecho de Sargassum en la costa norte del estado de São Paulo, Brasil. Los muestreos se realizaron mensualmente desde octubre de 2010 hasta febrero de 2012. En cada mes, se recolectaron al azar 25 frondas de Sargassum a través de snorkel. Los caprélidos fueron identificados, contados, clasificados por sexo y separados en clases de tamaño. Caprella danilevskii fue la especie más abundante, con 14939 ejemplares registrados. El tamaño corporal de los machos fue mayor que el de las hembras para C. danilevskii y C. equilibra y la proporción de sexos se inclinó hacia los machos para todas las especies. La distribución de frecuencia de tamaño fue polimodal para C. danilevskii y C. scaura y bimodal para C. equilibra. Se registraron machos maduros de C. scaura y C. equilibra en todas las clases de tamaño. Las últimas clases de tamaño (de 8,3–9,4 a 12,7–13,8 mm) estuvieron dominadas por machos maduros. Las hembras maduras y ovígeras fueron más frecuentes en clases de tamaño intermedio. Se registraron variaciones temporales significativas para las tres especies con mayores densidades en primavera y verano que están relacionadas con una mayor biomasa de algas; pero otros factores ambientales son ciertamente importantes para explicar la variación de la densidad de los caprélidos

Biodiversidade de caranguejos Branquiúros (Crustacea, Decapoda) associada a bancos da alga Sargassum cymosum (C. Agardh, 1820) na região da Ubatuba, Litoral Norte Paulista

O objetivo desta investigação é descrever e comparar a comunidade de decápodos braquiúros associados a bancos da alga S. cymosum (C. Agardh, 1820), em duas praias do litoral norte paulista. Foram realizadas coletas mensais durante o período de janeiro a dezembro de 2001, na região do entre-marés no substrato rochoso em bancos de S. cymosum nas praias Grande (23º23’S–45º03’W) e Domingas Dias (23º29’S–45º08’W), em Ubatuba. Em laboratório, os caranguejos foram submetidos a identificação taxonômica, mensurados quanto a largura de carapaça (LC) e identificados quanto ao sexo e fase do desenvolvimento. Foram obtidos 1948 indivíduos, reunidos em 23 espécies. Na praia Grande foram coletados 1115 indivíduos, distribuídos em 20 espécies, pertencentes a 5 superfamílias. Para a praia Domingas Dias foram obtidos 833 indivíduos, entre os quais foram registradas 21 espécies, de 4 superfamílias. Para a praia Domingas Dias Epialtus bituberculatus foi a espécie dominante enquanto que para a praia Grande, a dominância foi compartilhada por E. bituberculatus, Menippe nodifrons. Houve diferença significativa acerca do índice de diversidade (Mann-Whitney; p=0,0130) entre as praias, sendo que a praia Grande apresentou o maior valor para o índice (1,86nats/ind.). Essa diferença observada para a diversidade entre as praias Grande e Domingas Dias, pode refletir o fato de que ambientes mais heterogêneos geralmente abrigam maiores diversidades, sendo a praia Grande considerada como um ambiente mais heterogêneo e sujeita a maior exposição aos distúrbios ambientais, como ação de ondas, apresentando dominância compartilhada entre duas espécies enquanto a praia Domingas Dias, mais estável, apresentou expressiva dominância de uma única espécie, o que promoveu um baixo valor para o índice de diversidade. Desse modo, a maior ou menor exposição às ondas...The objective of this research was to describe and compare the communities of brachyuran decapods associated with banks of the seaweed Sargassum cymosum (C. Agardh, 1820), on two beaches of the northeastern coast of São Paulo State. Monthly collections were conducted from January to December 2001, in seaweed banks on the intertidal rocky bottoms of the Grande (23º23'S-45°03'W) and Domingas Dias beaches (23º29'S-45º08'W). In the laboratory, the crabs were identified to species level and measured for carapace width (CW), sexed, and their developmental stage identified. A total of 1948 individuals were obtained, representing 23 species. On Grande Beach, 1115 individuals were captured, of 20 species in 5 superfamilies. On Domingas Dias Beach, 833 individuals were obtained, of 21 species in 4 superfamilies. On Domingas Dias Beach, Epialtus bituberculatus was the dominant species, whereas on Grande Beach, dominance was shared between E. bituberculatus and Menippe nodifrons. The diversity index differed significantly (Mann-Whitney, p=0.0130) between the beaches, being higher at Grande (1.86 bits/ind.). This difference in diversity is due to the fact that more heterogeneous environments generally show a greater diversity. Two co-dominant species occurred at Grande Beach, which is a more heterogeneous environment, exposed to environmental disturbances such as wave motion. A significant dominance of only one species was recorded at the more stable Domingas Dias Beach, which showed a low diversity index. In this investigation, wave motion appeared to have a strong influence on the species selection process on the rocky shore... (Complete abstract click electronic access below)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Ocupação de substratos artificiais por caranguejos braquiuros (Crustacea, Decapoda) no sublitoral rochoso do Ilhote das Couves, litoral norte paulista

Estudos que visam à ocupação de organismos em substratos artificiais (SA) podem fornecer informações sobre o desenvolvimento de metodologias para o gerenciamento ambiental. Este estudo teve como objetivo descrever a ocupação de SA por caranguejos braquiuros no sublitoral rochoso de uma região insular. Quinze unidades de SA de concreto foram construídas e ornamentadas com fibra sintética, tubo plástico e brita (dimensões: 40cm X 25cm X 10cm e 16kg). Todos SA foram instalados, aleatoriamente, ao mesmo tempo (T0 = fevereiro/2010), durante sessões de mergulho autônomo, no sublitoral rochoso na região do Ilhote das Couves (23º25'15''S-44º51'39''W), litoral norte paulista. Foram obtidos 521 caranguejos, distribuídos em 8 famílias e 25 espécies, sendo a família Majidae a mais representativa com 27,8% e Mithraculus forceps, o caranguejo mais abundante. Mais de 65% dos indivíduos capturados eram menores que 5 mm de largura da carapaça e mais de 80% eram indivíduos juvenis. Não foi registrada correlação entre a composição de braquiuros e a biomassa da fauna acompanhante (C=0,06; p=0,29). A maior abundância absoluta, riqueza e diversidade de Shannon-Wiener nos substratos foram registradas em T5, com 88 indivíduos, 11 espécies e 2,95 bits/ind., respectivamente. Diante desses resultados, sugere-se que o tempo de exposição desses SA seja o principal fator que contribui com a variação dos parâmetros ecológicos. Adicionalmente, verificou-se que o SA é rapidamente ocupado por espécies do ambiente natural adjacente, porém a fauna de braquiuros é selecionada pelo tamanho dos refúgios disponíveis nessas estruturasStudies on the occupation of organisms on artificial substrates (AS) can provide helpful information for an effective environmental management. This study described the occupation of AS by brachyuran crabs on the rocky subtidal of an insular region. Fifteen concrete units of AS were built and embellished with synthetic fiber, plastic tube and gravel (dimensions: 40 cm x 25 cm x 10 cm and 16 kg). All AS were randomly placed at the same time (T0 = February/2010), during SCUBA diving, on the rocky subtidal of Ilhote das Couves (23º25'15''S-44º51'39''W), on the north coast of São Paulo. A total of 521 crabs were collected, in 8 families and 25 species. The Majidae family was the most abundant, comprising 27.8% of the total and Mithraculus forceps, the most abundant species. More than 95% of the captured individuals were smaller than 10 mm of carapace width and over 80% were juveniles. No correlation was found between the composition of brachyurans and the bycatch biomass (C=0.06; p=0.29). The highest absolute abundance, richness and Shannon-Wiener diversity index on the substrates were found in T5, with 88 individuals, 11 species and 2.95 bits/ind., respectively. These results suggest that the time of exposure of AS is the main contributor to the variation in ecological parameters. Additionally, the AS is quickly occupied by species from the adjacent natural habitat, and the brachyuran fauna is selected by the size of available refuge in these structure

Comparison of the population biology of Epialtus bituberculatus from two rocky shores with distinct hydrodynamic patterns

The population biology of Epialtus bituberculatus was compared between two different intertidal localities with differing levels of wave exposure. Sampling was conducted monthly between January and December, 2001 on seaweed banks of Sargassum cymosum in the intertidal zone of the rocky shores Grande (GR) (23°23′S-45°03′W) and Domingas Dias (DD) (23°29′S-45°08′W). Four hundred and twenty-eight crabs were captured at the GR site: 111 juvenile males, 106 adult males, 57 juvenile females, 17 adult females and 137 ovigerous females; while 455 specimens were obtained at the DD site: 76 juvenile males, 113 adult males, 37 juvenile females, 40 adult females and 189 ovigerous females. The population from GR showed a non-normal distribution and from DD a normal distribution. The sex-ratio (female/male) was 1:0.97 at GR (χ2 = 0.77, P = 0.084), whereas it was 1:1.41 at DD (χ2 = 13.03, P < 0.001). The largest individuals occurred at DD (U = 78249.0, P < 0.001). The estimated size at sexual maturity was 6.3 and 5.0 mm carapace width (CW) for males, and 5.4 and 5.2 mm CW for females, from GR and DD, respectively. The observed differences in E. bituberculatus between the studied localities might be explained by the different degrees of wave exposure between sites. However, other factors that might also explain the observed differences (e.g. temperature, salinity and food availability) cannot be discarded as relevant in influencing the population structure between sites herein studied. © 2012 Marine Biological Association of the United Kingdom

Morphological remarks on the peppermint shrimp Lysmata ankeri (Decapoda, Hippolytidae): implications for species identification of the L. wurdemanni complex

ABSTRACTThis contribution reviews the morphology and the main diagnostic characters of the peppermint shrimp Lysmata ankeri. Individuals were sampled by scuba divers from August 2008 to June 2013 on the subtidal rocky bottom at Couves Island, on the coast of São Paulo State, Brazil. In the laboratory, the individuals were analyzed morphologically, with emphasis on the characters used in the diagnosis of the species; measured as carapace length (CL); and photographed. Seventeen individuals of L. ankeri were analyzed with an average size of 6.9 ± 2.0 mm CL. From the morphological analysis the following variations of the diagnosis were observed: five teeth on the dorsal margin of the rostrum, in the diagnosis this was 6-8; five spines on the flexor margin of the dactyli of pereiopods 2-4, in the diagnosis this was 3-4. The records of this study extend the knowledge of the variation of some morphological characteristics for this species, resulting in an overlap among the species of the Lysmata wurdemanni complex

Mithracinae (Decapoda: Brachyura) from the Brazilian coast: review of the geographical distribution and comments on the biogeography of the group

The geographical distribution of marine organisms, as a result of complex natural processes through geological time, has been changed, sometimes drastically, by species introductions. Instances of species introduction have been recorded worldwide, and the Brazilian coast is no exception. The present review provides an update of the geographical distribution of members of the brachyuran subfamily Mithracinae along the Brazilian coast. Of the 30 species of this subfamily recorded from Brazilian waters, the known geographical limits of more than 17 have been extended in recent decades. The records compiled here demonstrate the great importance of the Amazon River outflow on the geographical distribution of members of Mithracinae, acting as a biogeographical barrier for some species

Sexual system, reproductive cycle and embryonic development of the red-striped shrimp Lysmata vittata, an invader in the western Atlantic Ocean.

Several decapod crustaceans are invaders, but little is known about the biological characteristics that potentiate the success of these decapods in invaded ecosystems. Here, we evaluate and describe some aspects of the reproductive biology and development of Lysmata vittata, an invasive shrimp species in the Atlantic Ocean. In addition, we intend to provide important insights into the biology of invasion by comparing the reproductive traits of this shrimp with some of the predictions about aquatic invasive species. We used experimental and laboratory observations to evaluate the functionality of protandric simultaneous hermaphroditism (PSH), the macro and microscopic development of the ovarian portion of the ovotestes, the reproductive cycle, and the embryonic development of L. vittata. We confirm the functionality of PSH in L. vittata. This shrimp has a rapid reproductive cycle; the ovarian portion of the ovotestes develops (mean ± SD) 6.28 ± 1.61 days after spawning. Embryonic development also occurs over a short time, with a mean (± SD) of 8.37 ± 0.85 days. The larvae hatch without macroscopically visible yolk reserves. Our study provides evidence that the invasive shrimp L. vittata has reproductive and embryonic developmental characteristics (i.e., short generation time and high reproductive capacity) that may be favorable to the establishment of populations during invasive processes

Mithracinae (Decapoda: Brachyura) from the Brazilian coast: review of the geographical distribution and comments on the biogeography of the group

The geographical distribution of marine organisms, as a result of complex natural processes through geological time, has been changed, sometimes drastically, by species introductions. Instances of species introduction have been recorded worldwide, and the Brazilian coast is no exception. The present review provides an update of the geographical distribution of members of the brachyuran subfamily Mithracinae along the Brazilian coast. Of the 30 species of this subfamily recorded from Brazilian waters, the known geographical limits of more than 17 have been extended in recent decades. The records compiled here demonstrate the great importance of the Amazon River outflow on the geographical distribution of members of Mithracinae, acting as a biogeographical barrier for some species

Importancia de los sustratos biogénicos para el cangrejo de piedra Menippe nodifrons Stimpson, 1859 (Brachyura: Eriphioidea)

In order to better understand the ecology of the different growth phases of the stone crab, Menippe nodifrons, and provide information for conservation of the natural stocks, this study describes the utilization of different biogenic substrates by this species in the intertidal zone. Sampling was carried out by hand at Ubatuba, State of São Paulo, Brazil. Crabs were captured among rocks or in association with three different biogenic substrates: Phragmatopoma lapidosa, Sargassum cymosum and Schizoporella unicornis. In the laboratory, the substrates were sorted and scanned for specimens of M. nodifrons, which were separated and measured at their maximum carapace width (CW), and classified as juvenile or adult specimens. Sex ratio and size distribution of crabs were analyzed for each of the substrate types. A total of 686 specimens of M. nodifrons were obtained during the sampling, ranging in size between 2.4 and 82.5 mm CW. Different mean sizes were recorded in the different substrates (P < 0.05). The high prevalence of juveniles in the samples suggests that these microhabitats are fundamental for the juvenile development of M. nodifrons, as they provide refuge, protection and probably food for juveniles.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP