The invasive kelp Undaria pinnatifida (Laminariales, Ochrophyta) along the north coast of Portugal: distribution model versus field observations.

After the first report of Undaria pinnatifida in north Portugal (between 1999 and 2007), a rapid spread of this species could be expected due to the presence of a stable population and the favourable environmental conditions proposed by distribution models. However, field surveys showed that U. pinnatifida was not present in most of the rocky shores in north Portugal. It seems that U. pinnatifida cannot outcompete native species outside of marinas in north Portugal. The only population in natural rocky shores was found in Buarcos, where this species was frequent. This study provides density data of U. pinnatifida that will be useful in the future to monitor changes on its abundance and distribution in the centre and south of Portugal.

Invasion of Sargassum muticum in intertidal rockpools: patterns along the Atlantic Iberian Peninsula.

Spatial patterns of non-indigenous species show scale-dependent properties. Sargassum muticum is an invasive macroalga widely distributed along the Atlantic Iberian Peninsula. Despite being quite abundant from Norway to South Portugal, there is little information about its patterns of distribution, particularly at a large spatial scale (i.e. thousands of kilometres). Here, we examined the spatial variation in the invasion success of S. muticum from rockpools at multiple spatial scales using a hierarchical design. In addition, we analysed how the richness of native assemblages was related to its invasion success and how this relationship changed over different scales. Most of the variation in the invasion success was found at the smallest scales of pool and plot. Furthermore, the invasibility of native macroalgal assemblages was related to the native species richness, but causes that determined invasion success could not be separated from the effects provoked by the invader. Results suggest that small-scale (centimetres to metres) processes contribute considerably to the heterogeneity of S. muticum invasion success.

Physical factors driving intertidal macroalgae distribution: physiological stress of a dominant fucoid at its southern limit.

Climate change is driving species range shifts worldwide. However, physiological responses related to distributional changes are not fully understood. Oceanographers have reported an increase in ocean temperature in the northwest Iberian Peninsula that is potentially related to the decline in some cold-temperate intertidal macroalgae in the Cantabrian Sea, namely Fucus serratus. Low tide stress could also play a role in this decline. We performed one mensurative (in situ) and two manipulative (in culture) experiments designed to evaluate the interactive effects of some physical factors. The first experiment analysed field response to low tide stress in marginal (mid-Cantabrian Sea and northern Portugal) versus central (Galicia) populations of F. serratus. Then a second experiment was performed that utilized either harsh or mild summer conditions of atmospheric temperature, irradiance, humidity, and wind velocity to compare the responses of individuals from one marginal and one central population to low tide stress. Finally, the combined effect of sea temperature and the other factors was evaluated to detect interactive effects. Changes in frond growth, maximal photosynthetic quantum yield (F(v)/F(m)), temperature, and desiccation were found. Three additive factors (solar irradiation, ocean and air temperatures) were found to drive F. serratus distribution, except under mildly humid conditions that ameliorated atmospheric thermal stress (two additive factors). Mid-Cantabrian Sea temperatures have recently increased, reaching the inhibitory levels suggested in this study of F. serratus. We also expect an additive secondary contribution of low tide stress to this species decline. On the northern Portugal coast, ocean warming plus low tide stress has not reached this species' inhibition threshold. No significant differential responses attributed to the population of origin were found. Mechanistic approaches that are designed to analyse the interactive effects of physical stressors may improve the levels of confidence in predicted range shifts of species.

Two strategies to live in low chronic pollution estuaries: the potential role of lifestyle.

Although physiological and genetic adaptation to toxic stress has been the focus of recent research, the role of lifestyle in pollution tolerance has received less attention. In this study, copper tolerance of benthic and epi-benthic species of harpacticoid copepods was investigated. Concentration-response curves were generated for populations of both species but collected at contaminated and uncontaminated estuaries. The population of the benthic species from the contaminated site showed higher tolerance than its population from the uncontaminated site. The epi-benthic species showed no inter-specific differences in tolerance. The comparison of tolerance between field collected animals of the benthic species and animals from the same population but reared in the laboratory for two generations suggested the existence of a genetic inherited tolerance. Results revealed the importance that lifestyle may have on the generation of tolerance to toxic substances and highlight a potential unforeseen role of it in maintenance of biodiversity on contaminated habitats.

Shallow sublittoral meiofauna communities and sediment polycyclic aromatic hydrocarbons (PAHs) content on the Galician coast (NW Spain), six months after the Prestige oil spill.

The aim of this work was to detect the impact of Prestige oil spill on meiobenthic community structure at higher levels of taxonomic aggregation. In addition, the relationship between sediment individual polycyclic aromatic hydrocarbon (PAH) concentration and meiofauna community structure was investigated. Six months after the Prestige oil spill, meiobenthos community and sediment PAHs content from seven shallow subtidal localities along the Galician coast were studied. Two sites presented differences in community structure, characterized by high densities of nematodes, gastrotrichs and turbellarians, and low densities of copepods. Chrysene and triphenylene were only found at these two disturbed sites and could be responsible for differences of meiobenthos community structure. However, differences in community structure of sites could be linked with sedimentary parameters, and discrimination between the effect of PAHs and sedimentary parameters was impossible due to the lack of baseline studies on meiobenthos and PAHs contents in this area.