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Oliveira J.P.,Estacao Litoral da Aguda | Oliveira J.P.,University of Porto | Sousa-Pinto I.,University of Porto | Weber G.M.,Estacao Litoral da Aguda | And 3 more authors.
Marine Ecology Progress Series | Year: 2015

Coastal habitats are exposed to increasing human and natural disturbances, including extraction of organisms and extreme climatic events. Patterns of recovery (i.e. convergence towards an unmanipulated control) of the structure of benthic assemblages, the total number, and the abundance of individual taxa were examined over a period of 15 mo after the end of a previous experiment. In that experiment, crossed manipulations of levels of mussel harvesting and of the temporal patterns of storm-related mechanical disturbance (in terms of changes in variance but not in the overall intensity) were performed on north Portugal rocky shores. Effects of past disturbances were mostly detected at 3 and 9 mo after the end of disturbances, while no significant differences between unmanipulated and treated assemblages were present after 15 mo. These findings confirm that intertidal assemblages subjected to even extreme combinations of past disturbances can recover in a relatively short time. Important effects present after 3 to 9 mo were associated with the timing of disturbance, likely depending on interactions with life-history traits such as peaks in reproduction and recruitment. Contrary to theories considering disturbances as opportunities for some organisms to replace competitors that dominate space in undisturbed conditions, we observed changes in the abundances of the same taxa rather than their replacement. The present evidence contributes to the understanding of how multiple anthropogenic pressures affect the ability of intertidal assemblages to recover after disturbance. © Inter-Research 2015, www.int-res.com.

Oliveira J.P.,Estacao Litoral da Aguda | Oliveira J.P.,University of Porto | Sousa-Pinto I.,University of Porto | Weber G.M.,Estacao Litoral da Aguda | And 3 more authors.
Marine Environmental Research | Year: 2014

Littoral areas are subject to severe and increasing pressures resulting from human activities occurring along or next to the coast. In this study, patterns of variability in the structure of rocky intertidal benthic assemblages and in the abundance of individual taxa were compared between locations close to the coastal cities of Porto and Vila Nova de Gaia (north Portugal) and reference locations far from it in much less urbanized conditions over a temporal scale of fourteen months and multiple spatial scales. Present findings indicated that assemblages were more heterogeneously distributed in the urban than in the extra-urban condition. The total number of taxa and several individual taxa displayed, in general, this same pattern of variability. This could be interpreted as the beginning of a habitat deterioration process with largely unpredictable consequences. The adopted sampling design supports the need for simultaneously including a range of temporal and spatial scales when evaluating responses of coastal marine biodiversity to anthropogenic disturbances. © 2014 Elsevier Ltd.

Oliveira J.P.,Estacao Litoral da Aguda | Oliveira J.P.,University of Porto | Oliveira J.P.,Abel Salazar Biomedical Sciences Institute | Bertocci I.,University of Porto | And 4 more authors.
Journal of Experimental Marine Biology and Ecology | Year: 2011

Patterns of recovery of rock pool assemblages were experimentally investigated along the rocky shore of Praia da Aguda (NW Portugal). The temporal variance in the structure of whole assemblages and abundance of individual algal and invertebrate organisms was examined after two experimental disturbances differing in intensity, i.e. one able to eliminate all the biota from the substratum, the other able to create a mosaic of bare patches interspersed within the remaining organisms. Two experimental trials were carried out (starting in March 2007 and July 2007, respectively), with a duration of the study of 13. months each. Multivariate results indicated a temporally consistent positive relationship between the intensity of disturbance applied and the temporal variance of the structure of assemblages. A similar response was documented at the univariate level by the encrusting coralline alga Lithophyllum incrustans and the foliose green algae of the genus Ulva, while both experimental disturbances decreased temporal fluctuations of the abundance of mussels, Mytilus galloprovincialis, compared to unmanipulated control. The present study has implications for understanding and predicting responses of intertidal assemblages to natural disturbances whose intensity is predicted to increase in the future, including climate events. © 2010 Elsevier B.V.

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