RESUMO

Modular organization provides flexibility for colonial animals to deal with variable and unpredictable environmental conditions since each module has specific tasks within the colony, such as feeding, defending or reproducing. Depending on the selecting pressures, sessile organisms may phenotypically adjust the morphology of each module or modify their density, increasing individual fitness. Here we used the marine bryozoan Schizoporella errata (Cheilostomata, Schizoporellidae) to test how the divergent conditions between two artificial habitats, the location inside a marina (IM) and the external wall of the breakwater (BW), affect colony size and the density of the distinct modules. The density of avicularia and ovicells, modules related to defense and reproduction, respectively, did not differ between habitats. However, colonies growing in the turbulent waters of BW were, in general, larger and had higher density of feeding autozooids than those at IM. Reciprocal transplants of bryozoan clones indicated that trait variation is genotype-dependent but varies according to the environmental conditions at the assigned location. The occurrence of larger colonies with more zooids in BW is probably linked to the easier feeding opportunity offered by the small diffusive boundary layer around the colony at this location. Since in colonial polymorphic organisms each module (zooid) performs a specific function, the phenotypic response is not uniform across colonies, affecting only those modules that are susceptible to variations in the main selective pressures. Understanding the importance of colony-level plasticity is relevant to predict how modularity will contribute to organisms to deal with human-induced environmental changes in coastal habitats.

Assuntos

RESUMO

Hippomonavella charrua n. sp. is introduced based on material from the continental shelf off Uruguay. Bilaminar fragments of this species were also found in mid-Holocene deposits of Destacamento Río Salado Member, Canal de las Escobas Formation (Buenos Aires Province, Argentina), ca. 6,000 yr BP. Hippomonavella charrua n. sp. resembles H. brasiliensis Ramalho, Muricy Taylor, 2008, but differs from this species in its more triangular and protruding avicularia occurring in just a small proportion of zooids. Hippomonavella charrua n. sp. is the third species of the genus with both fossil and Recent representatives. The tatiform ancestrula and the early astogeny are described for the first time in a species of Hippomonavella.

Assuntos

RESUMO

Global urbanization and plastic pollution has increased the availability and variety of substrates for sessile organisms, and are intensively used by invasive species for settlement. Despite extensive literature describing the strong association between artificial structures and invasive species, little effort has been directed towards identifying the larval traits that favor this selection. Larval selection and settlement are crucial as larvae actively search and interpret environmental cues to identify suitable habitats to settle. The aim of this research was to investigate if invertebrate larvae have a preference for a particular anthropogenic substrate, and how pre-settlement behaviors vary when encountering different substrates. We used two invasive bryozoan species, Bugula flabellata and Bugula neritina, which are commonly found in urbanized areas around the world. Energy expenditure during planktonic and benthonic stages, pre-settlement swimming/exploring behaviors, settlement and larval selectivity were quantified under laboratory conditions on different substrates (concrete, wood, polystyrene, polyvinyl chloride, polyethylene terephthalate and polycarbonate). The energy expenditure measured was higher in planktonic larvae than in early settled larvae. Larvae of both species swam less and explored more when exposed to plastic surfaces, suggesting a preference for this substrate and resulting in lower energy expenditures associated with searching for habitat. Larvae actively chose to settle on plastics rather than on wood or concrete substrates. The results suggest that for Bugula larvae, the likelihood of colonizing plastic surfaces is higher than other materials commonly found in urbanized coastal areas. The more quickly they adhere to artificial substrates the lower the energy expenditure, contributing to higher fitness in these individuals. The strong preference of invertebrate larvae for plastics can potentially extend the distribution range of many invasive marine species as they are able to travel long distances attached to floating debris. This phenomenon will likely exacerbate the introduction of exotic species into novel habitats.

Assuntos

RESUMO

A new species of the erect cheilostome bryozoan Cellaria Ellis & Solander, 1786 is described from Bahia, NE Brazil. Cellaria oraneae sp. nov. is the first formally characterized species of the genus reported from Northeastern coast of Brazil, distinguished from all congeners by the combination of hexagonal autozooids and rhomboid fertile zooids, hexagonal interzooidal avicularium with sagittate foramen, completely immersed ovicell with oval aperture and proximal rectangular lip. A brief discussion of the diversity of Cellaria from the Atlantic Ocean and a tabular identification key to these species are also provided.(AU)

Assuntos

RESUMO

A new species of the erect cheilostome bryozoan Cellaria Ellis & Solander, 1786 is described from Bahia, NE Brazil. Cellaria oraneae sp. nov. is the first formally characterized species of the genus reported from Northeastern coast of Brazil, distinguished from all congeners by the combination of hexagonal autozooids and rhomboid fertile zooids, hexagonal interzooidal avicularium with sagittate foramen, completely immersed ovicell with oval aperture and proximal rectangular lip. A brief discussion of the diversity of Cellaria from the Atlantic Ocean and a tabular identification key to these species are also provided.

Assuntos

RESUMO

Mean prevalence and intensity of infestations by epibionts were evaluated in Arenaeus cribrarius (Lamarck, 1818), based on monthly samplings (May/1991 to April/1993), in Ubatuba, Brazil. Bryozoans were quantified in terms of colony numbers and barnacles by the number of specimens. Prevalence of infestation was determined in 1,914 individuals of A. cribrarius and assessed with respect to sex, maturity stage and season. No significant interaction was detected between epibionts and biological host factors. Males showed a higher infestation rate by Chelonibia patula (Ranzani, 1818) when compared to mature non-ovigerous females, yet Octolasmis lowei Darwin, 1851 infestation was associated to adult crabs. The ovigerous females of A. cribrarius showed a higher prevalence of infestation than males and non-ovigerous females, with lower infestations being recorded during winter. A synchrony between the life cycle of the epibionts and their hosts was evident and promotes the continuity of the former in the area.

RESUMO

Mean prevalence and intensity of infestations by epibionts were evaluated in Arenaeus cribrarius (Lamarck, 1818), based on monthly samplings (May/1991 to April/1993), in Ubatuba, Brazil. Bryozoans were quantified in terms of colony numbers and barnacles by the number of specimens. Prevalence of infestation was determined in 1,914 individuals of A. cribrarius and assessed with respect to sex, maturity stage and season. No significant interaction was detected between epibionts and biological host factors. Males showed a higher infestation rate by Chelonibia patula (Ranzani, 1818) when compared to mature non-ovigerous females, yet Octolasmis lowei Darwin, 1851 infestation was associated to adult crabs. The ovigerous females of A. cribrarius showed a higher prevalence of infestation than males and non-ovigerous females, with lower infestations being recorded during winter. A synchrony between the life cycle of the epibionts and their hosts was evident and promotes the continuity of the former in the area.

RESUMO

Mean prevalence and intensity of infestations by epibionts were evaluated in Arenaeus cribrarius (Lamarck, 1818), based on monthly samplings (May/1991 to April/1993), in Ubatuba, Brazil. Bryozoans were quantified in terms of colony numbers and barnacles by the number of specimens. Prevalence of infestation was determined in 1,914 individuals of A. cribrarius and assessed with respect to sex, maturity stage and season. No significant interaction was detected between epibionts and biological host factors. Males showed a higher infestation rate by Chelonibia patula (Ranzani, 1818) when compared to mature non-ovigerous females, yet Octolasmis lowei Darwin, 1851 infestation was associated to adult crabs. The ovigerous females of A. cribrarius showed a higher prevalence of infestation than males and non-ovigerous females, with lower infestations being recorded during winter. A synchrony between the life cycle of the epibionts and their hosts was evident and promotes the continuity of the former in the area.