RESUMO
Human driven changes such as increases in oceanic CO2, global warming, petroleum hydrocarbons and heavy metals may negatively affect the ability of marine calcifiers to build their skeletons/shells, especially in polar regions. We examine spatio-temporal variability of skeletal Mg-calcite in shallow water Antarctic marine invertebrates using bryozoan and spirorbids as models in a recruitment experiment of settlement tiles in East Antarctica. Mineralogies were determined for 754 specimens belonging to six bryozoan species (four cheilostome and two cyclostome species) and two spirorbid species from around Casey Station. Intra- and interspecific variability in wt% MgCO3 in calcite among most species was the largest source of variation overall. Therefore, the skeletal Mg-calcite in these taxa seem to be mainly biologically controlled. However, significant spatial variability was also found in wt% MgCO3 in calcite, possibly reflecting local environment variation from sources such as freshwater input and contaminated sediments. Species with high-Mg calcite skeletons (e.g. Beania erecta) could be particularly sensitive to multiple stressors under predictions for near-future global ocean chemistry changes such as increasing temperature, ocean acidification and pollution.
Assuntos
Organismos Aquáticos/metabolismo , Carbonato de Cálcio/metabolismo , Magnésio/metabolismo , Esqueleto/metabolismo , Regiões Antárticas , Geografia , Análise Espaço-TemporalRESUMO
The breadth of habitat occupied by a species, and the rate at which a species can expand into new habitats has important ecological and evolutionary consequences. Here we explore when extant species of free-living cupuladriid bryozoans expanded into new benthic Caribbean habitats that emerged during the final stages of formation of the Isthmus of Panama. Habitat breadth was estimated using the abundances of over 90,000 colonies in ten cupuladriid species, along with the ecological and sedimentary characteristics of the samples in which they occurred. Data reveal that all species expanded their habitat breadths during the last 6 Myr, but did so at a different tempo. 'Young' species - those that originated after 5 Ma - expanded relatively quickly, whereas 'old' species - those that originated before 9 Ma - took a further 2 Myr to achieve a comparable level of expansion. We propose that, like invasive species, young species are less restrained when expanding their habitat breadths compared to older well-established species. Understanding the mechanism causing this restraint requires further research.
Assuntos
Briozoários/metabolismo , Animais , Biodiversidade , Evolução Biológica , Região do Caribe , Ecologia , Ecossistema , Espécies Introduzidas , Panamá , Dinâmica PopulacionalRESUMO
The present paper reports on 22 bryozoan species collected from 25 localities on the Southwestern Atlantic continental shelf and slope by the Instituto Español de Oceanografía vessel RV Miguel Oliver (2008-2010). Two new genera, Amynaskolia n. gen. and Biconcavus n. gen., and twenty new cheilostome species are described: Amastigia zigzag n. sp., Membranicellaria balanyai n. sp., Figularia dimorpha n. sp., Biconcavus batmani n. sp., Smittina acicularis n. sp., Smittoidea granulosa n. sp., Amynaskolia foramina n. sp., Mawatarius avilae n. sp., Mucropetraliella reticulata n. sp., Ipsibuffonella umbonata n. sp., Microporella gappai n. sp., Fenestrulina curviscutum n. sp., Fenestrulina multiflorum n. sp., Malakosaria cecilioi n. sp., Osthimosia incisa n. sp., Spigaleos simplex n. sp., Reteporella kuklinskii n. sp., Reteporella maryae n. sp., Reteporella taylori n. sp., Orthoporidra nova n. sp.. New taxonomic remarks are also included for two little-known species: Melicerita atlantica Busk, 1884 and Arachnopusia tubula Hayward Thorpe, 1988. Membranicellaria balanyai n. sp., Mawatarius avilae n. sp. and Ipsibuffonella umbonata n. sp. represent the third described species of their genera, whereas Spigaleos simplex n. sp., Malakosaria cecilioi n. sp. and Orthoporidra nova n. sp. are the fourth, fifth and sixth described species of their genera respectively. Spigaleos (Celleporidae) and Arachnopusia tubula (Arachnopusiidae), previously reported only from Antarctica, Ipsibuffonella (Buffonellodidae), reported from tropical and subtropical regions, and Mucropetraliella (Petraliidae) all represent first records for the Patagonian region, expanding their geographic distributions northwards and southwards, respectively. These results highlight the importance of sampling the slope and deep waters of South American and Antarctic margins and basins, filling significant gaps in the knowledge of the biodiversity and biogeographic ranges of certain taxa in these unique and varied ecosystems.