Novas observações sobre as cracas (Crustacea: Cirripedia) na região dos Açores

São feitas actualizações, adições e revisões à lista de cirrípedes (Cirripedia) registados para os Açores, incluindo amostras obtidas em fontes hidrotermais e na zona intertidal. São descritas observações na distribuição e reprodução da espécie Tesseropora atlantica, uma espécie oceânica relíquia, não descrita nos continentes, que incuba as larvas até à breve fase larvar de cypris. O grau de endemicidade das cracas dos Açores está a ser actualmente registada, mas a maioria das espécies identificadas nos Açores estão amplamente distribuídas no Atlântico e Mediterrâneo. A diversidade das espécies costeiras é reduzida.ABSTRACT: Additions and revisions are made to the list of Cirripedia recorded from the Azores, including samples taken near hydrothermal vents and in the intertidal zone. Observations are reported on the distribution and breeding of Tesseropora atlantica, a relict oceanic species, not found on the continents, that incubates its larvae to the short-lived cypris stage. The degree of endemicity of Azorean barnacles is currently being revised, but most species reported from the Azores are widely distributed in the Atlantic and the Mediterranean. The diversity of the shallow water group is low

Cirripedia of Madeira

We give a list of Cirripedia from Madeira Island and nearby deep water, based on specimens in the collection of the Museu Municipal do Funchal (Historia Natural) (MMF), records mentioned in the literature, and recent collections. Tesseropora atlantica Newman and Ross, 1976 is recorded from Madeira for the first time. The Megabalanus of Madeira is M. azoricus. There are 20 genera containing 27 species, of which 22 occur in depths less than 200 m. Of these shallow water species, eight are wide-ranging oceanic forms that attach to other organisms or to floating objects, leaving just 13 truly benthic shallow water barnacles. This low diversity is probably a consequence of the distance from the continental coasts and the small area of the available habitat. No endemic species have been found

Learning biophysically-motivated parameters for alpha helix prediction

<p>Abstract</p> <p>Background</p> <p>Our goal is to develop a state-of-the-art protein secondary structure predictor, with an intuitive and biophysically-motivated energy model. We treat structure prediction as an optimization problem, using parameterizable cost functions representing biological "pseudo-energies". Machine learning methods are applied to estimate the values of the parameters to correctly predict known protein structures.</p> <p>Results</p> <p>Focusing on the prediction of alpha helices in proteins, we show that a model with 302 parameters can achieve a Q_{<it>α </it>}value of 77.6% and an SOV_{<it>α </it>}value of 73.4%. Such performance numbers are among the best for techniques that do not rely on external databases (such as multiple sequence alignments). Further, it is easier to extract biological significance from a model with so few parameters.</p> <p>Conclusion</p> <p>The method presented shows promise for the prediction of protein secondary structure. Biophysically-motivated elementary free-energies can be learned using SVM techniques to construct an energy cost function whose predictive performance rivals state-of-the-art. This method is general and can be extended beyond the all-alpha case described here.</p

Detection of environmental change in a marine ecosystem—evidence from the western English Channel

To separate human-induced changes from natural fluctuations in marine life requires long-term research. The western English Channel has been investigated from Plymouth for over 100 years. The abundance of marine life has been recorded and related to physical changes in the environment. By comparing different parts of the ecosystem we can demonstrate historic natural fluctuations, allowing prediction of effects of future global change. From the 1920s to the 1950s there was a period of warming of the sea, with increases in abundance of species of fish, plankton and intertidal organisms that are typically common in warmer waters to the south of Britain. After 1962 the sea cooled down and northern cold-water species became more abundant. Since the 1980s regional sea surface temperature has increased again and warm-water species are once more becoming abundant

New records of cirripedes from Trinidad and Tobaco

An earlier report (BACON, 1976) described collections of Cirripedes from Trinidad containing 26 species. These included 4 Lepadomorpha, 21 Balanomorpha and 1 Sacculinid from intertidal and shallow water habitats. Eight additional species are reported on here, further notes are given on two of the Cirripedes listed previously and on a recent revision of the Trinidad Chthamalidae by DANDO & SOUTHWARD (1980). Information on the sister island of Tobago is sparse. BOSCHMA (1931, 1969) recorded Sacculina bicuspidata and Lernaeodiscus crenatus on crabs and SOUTHWARD (1975) listed only Lepas anatifera, Tetraclita stalactifera, Tetraclitella divisa and one species of Chthamalus from intertidal localities. A provisional list of the Cirripedes of Tobago is given here, using these literature sources and unpublished records

Modeling the response of populations of competing species to climate change

Abstract. Biotic interactions will modulate species&apos; responses to climate change. Many approaches to predicting the impacts of climate change on biodiversity so far have been based purely on a climate envelope approach and have not considered direct and indirect species interactions. Using a long-term observational data set (.30 years) of competing intertidal barnacle species, we built a hierarchy of age-structured two-taxa population models (Semibalanus balanoides vs. Chthamalus montagui and C. stellatus combined as one taxon) to test if the presence of a dominant competitor can mediate climatic influence on the subordinate species. Models were parameterized using data from populations on the south coast of southwest England and verified by hindcasting using independent north coast population data. Recruitment of the dominant competitor, S. balanoides, is driven by temperature. The mechanisms of competition explored included simple space preemption and temperature-driven interference competition. The results indicate that interspecific competition between juvenile barnacles is important in regulating chthamalid density but not that of the dominant competitor S. balanoides. Simulations were carried out using alternative future climate scenarios to predict barnacle population abundance over the next century. Under all emission scenarios, the cold-water S. balanoides is predicted to virtually disappear from southwest England by the 2050s, leading to the competitive release of Chthamalus throughout the entire region and thereby substantially increasing its abundance and occupied habitat (by increasing vertical range on the shore). Our results demonstrate that climate change can profoundly affect the abundance and distribution of species through both the direct effects of temperature on survival, and also by altering important negative interactions through shifting competitive balances and essentially removing dominant competitors or predators. Climate change impacts on organisms are unlikely to lead only to straightforward, easily predictable changes in population size and distribution. The complex, indirect effects of climate change need to be taken into account if we are to accurately forecast the long-term effects of global warming

Predicting the effects of marine climate change on the invertebrate prey of the birds of rocky shores

By the end of the 21st century models of climate change predict that the air temperature over most of the British Isles will increase by between 2 and 3 °C and sea-level will rise by 40–50 cm. Over that period it will become windier and mean wave height will increase, as will the frequency of storms. These changes in climate and weather will impact the intertidal zone of the UK and will cause distribution changes in many of the common invertebrate species that live there. Where these changes are severe they may well impact on patterns of distribution of ducks and wading birds. In the British Isles a number of organisms live close to their geographical limits of distribution. Some of these species might be expected to extend their range as climatic restraints are relaxed. Species currently limited by cool summers or winter cold will move northwards. In most cases the effects on the distribution of waterbirds will be small. For example, the replacement of the Northern Limpet Patella vulgata by the Southern Limpet P. depressa is unlikely to adversely affect Eurasian Oystercatchers Haematopus ostralegus. Of wider concern is the possibility that as climate warms the abundance and productivity of brown algae will decrease. This is likely to have two significant effects for waders. First, it would represent a loss of potentially rich feeding grounds for species such as Ruddy Turnstone Arenaria interpres that feed on small easily desiccated invertebrates living on or below the seaweed. Secondly, as algae die or are broken away the resulting debris is exported to sediment habitats where it considerably boosts the in situ production of bacteria at the base of the food web. An increase in sea-level will only have a major impact on the extent of rocky shore invertebrate communities where shore topography prevents the upward migration of the biota. Where a seawall limits shores, for example, biological production will be curtailed as the area available for colonization decreases. Increases in the size of waves and the frequency of storms will mimic increasing exposure and there will be a significant reduction in algal production in areas that are affected