Being young in a changing world: how temperature and salinity changes interactively modify the performance of larval stages of the barnacle Amphibalanus improvisus

The fate of key species, such as the barnacle Amphibalanus improvisus, in the course of global change is of particular interest since any change in their abundance and/or performance may entail community-wide effects. In the fluctuating Western Baltic, species typically experience a broad range of environmental conditions, which may preselect them to better cope with climate change. In this study, we examined the sensitivity of two crucial ontogenetic phases (naupliar, cypris) of the barnacle toward a range of temperature (12, 20, and 28°C) and salinity (5, 15, and 30 psu) combinations. Under all salinity treatments, nauplii developed faster at intermediate and high temperatures. Cyprid metamorphosis success, in contrast, was interactively impacted by temperature and salinity. Survival of nauplii decreased with increasing salinity under all temperature treatments. Highest settlement rates occurred at the intermediate temperature and salinity combination, i.e., 20°C and 15 psu. Settlement success of “naive” cyprids, i.e., when nauplii were raised in the absence of stress (20°C/15 psu), was less impacted by stressful temperature/salinity combinations than that of cyprids with a stress history. Here, settlement success was highest at 30 psu particularly at low and high temperatures. Surprisingly, larval survival was not highest under the conditions typical for the Kiel Fjord at the season of peak settlement (20°C/15 psu). The proportion of nauplii that ultimately transformed to attached juveniles was, however, highest under these “home” conditions. Overall, only particularly stressful combinations of temperature and salinity substantially reduced larval performance and development. Given more time for adaptation, the relatively smooth climate shifts predicted will probably not dramatically affect this species

Comunidades macrobentónicas del intermareal rocoso a lo largo de un gradiente estuarino de gran escala

We evaluated relationships between (1) salinity and species richness and (2) frontal zones and community structure for the rocky intertidal macrobenthic community of the Uruguayan coast. A large-scale sampling design (extent ~500 km) covering 9 rocky shores across 3 intertidal levels was performed between September and November 2002. The linear relationship between salinity and species richness (minimum at the freshwater extreme) and the lack of correlation between variation in salinity and richness rejected two previous empirical models, explaining variations in species richness along the salinity gradient. Other factors (e.g. turbidity) may explain this discrepancy. The estuarine front defined two communities—freshwater and estuarine-marine—differing in species composition and richness. The freshwater community was characterised by low richness and few individuals confined to crevices or tide pools, and must be structured by physical processes (e.g. desiccation); the estuarine-marine community, with individuals occupying almost all available substrata, must be structured by both physical and biological processes. A marine front, separating estuarine and marine habitats, had a weak effect on community structure although estuarine and marine assemblages differed according to species characterising different functional groups. We conclude that the position of the estuarine frontal zones is important for explaining large-scale patterns of community structure in the study area.En este trabajo evaluamos las relaciones entre (1) la salinidad y la riqueza específica, y (2) las zonas frontales y la estructura de la comunidad macrobentónica del intermareal rocoso de la costa uruguaya. Un diseño de muestreo de gran escala, aplicado entre septiembre y noviembre de 2002, cubrió 9 puntas rocosas y 3 niveles intermareales. La relación lineal entre la riqueza específica y la salinidad (mínima riqueza hacia el extremo dulceacuícola del gradiente) y la ausencia de relación entre la riqueza y las variaciones temporales en la salinidad descartaron dos modelos previos que intentaban explicar las variaciones de riqueza a lo largo del gradiente salino. Otros factores (e.g. turbidez) podrían explicar estas discrepancias. El frente salino definió dos comunidades, de agua dulce y estuarina-marina, diferenciadas en su composición y riqueza específica. La comunidad dulceacuícola se caracterizó por pocos individuos, confinados a grietas o piletas de marea y estaría estructurada por procesos físicos (e.g. desecación). La comunidad estuarina-marina, compuesta por un mayor número de especies, ocupando casi la totalidad del sustrato disponible, estaría estructurada por procesos físicos e interacciones biológicas. El frente marino, que separa los hábitats marinos y estuarinos, tuvo un efecto reducido sobre la estructura de la comunidad, aunque se pudieron diferenciar agrupaciones marinas y estuarinas a partir de especies de diferentes grupos funcionales. A partir de estos resultados, concluimos que la posición del frente estuarino es importante para explicar los patrones de gran escala en la comunidad estudiada

Stress ecology: interactive effect of temperature and salinity on early life stages of the barnacle, Amphibalanus improvisus

Marine Ecolog

Likelihood of Marine Pest introduction to the Indian Ocean Territories

The introduction of new species to environments in which they did not evolve has been widely recognised as one of the top five threats to marine ecosystem function and to biodiversity (Millennium Ecosystem Assessment, 2005)