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Deudero S.,Spanish Institute of Oceanography | Vazquez-Luis M.,Spanish Institute of Oceanography | Alvarez E.,Govern de les Illes Balears
PLoS ONE | Year: 2015

Coastal degradation and habitat disruption are severely compromising sessile marine species. The fan shell Pinna nobilis is an endemic, vulnerable species and the largest bivalve in the Mediterranean basin. In spite of species legal protection, fan shell populations are declining. Models analyzed the contributions of environmental (mean depth, wave height, maximum wave height, period of waves with high energy and mean direction of wave source) versus human-derived stressors (anchoring, protection status, sewage effluents, fishing activity and diving) as explanatory variables depicting Pinna nobilis populations at a mesoscale level. Human stressors were explaining most of the variability in density spatial distribution of fan shell, significantly disturbing benthic communities. Habitat protection affected P. nobilis structure and physical aggression by anchoring reveals a high impact on densities. Environmental variables instead played a secondary role, indicating that global change processes are not so relevant in coastal benthic communities as humanderived impacts. © 2015 Deudero et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Source


Vazquez-Luis M.,Spanish Institute of Oceanography | Banach-Esteve G.,Spanish Institute of Oceanography | Alvarez E.,Govern de les Illes Balears | Deudero S.,Spanish Institute of Oceanography
Journal of the Marine Biological Association of the United Kingdom | Year: 2014

Introduction of species is a major driver of global change and loss of biodiversity in ecosystems. The Mediterranean Sea is the most heavily invaded region in the world by introduced seaweeds. The fan mussel Pinna nobilis is the largest Mediterranean bivalve, and a protected species, present at depths from 0.5 m to 60 m. In Cabrera National Park marine protected area (MPA) (Balearic Islands, north-western Mediterranean) the population of P. nobilis is affected by the invasive seaweeds Lophocladia lallemandii and Caulerpa racemosa; however the extent of this colonization on the bivalve is unknown. Therefore, the main aims of the present study were to: (1) determine the extent of invasion of L. lallemandii and C. racemosa on the P. nobilis population; and (2) test if this invasion showed differences with depth. This is the first study assessing invasion by seaweeds on a large bivalve in a high density P. nobilis population. Pinna nobilis was distributed in all seagrass meadows surveyed within the MPA; we found a total of 872 live P. nobilis individuals, 449 and 423 of which were found at 10 and 20 m depth, respectively. High cover of L. lallemandii and low presence of C. racemosa were detected in the P. nobilis population, being quantified in 49.37% and 1.38% of the population of P. nobilis, respectively. Bathymetric differences on Lophocladia epizoism over P. nobilis has been recorded in this study; with increasing values of L. lallemandii cover index, biomass and volume at deeper depths. Pinna nobilis could be a preferential substratum for L. lallemandii in Posidonia oceanica meadows in deeper waters, acting as a stepping-stone for invasive seaweeds and facilitating the invasion throughout seagrass meadows. Copyright © Marine Biological Association of the United Kingdom 2014. Source


Vazquez-Luis M.,Spanish Institute of Oceanography | March D.,CSIC - Mediterranean Institute for Advanced Studies | Alvarez E.,Govern de les Illes Balears | Alvarez-Berastegui D.,SOCIB Balearic Islands Coastal Observing and Forecasting System Parc Bit | Deudero S.,Spanish Institute of Oceanography
Mediterranean Marine Science | Year: 2014

The spatial distribution of Pinna nobilis densities have been analysed through a geostatistical approach in the MPA of Cabrera National Park, Balearic Islands (Spain), Western Mediterranean Sea. Regression kriging was used to model the effect of environmental variables on the density of living individuals of P. nobilis and generate a predictive map of its distribution within the MPA. The environmental variables considered for the model were: depth; slope; habitat type and heterogeneity; wave exposure; and MPA zoning. A total of 378 transects were randomly distributed with a total of 149,000 m2 surveyed at a depth range from 4.2 to 46 m. The recorded P. nobilis densities are among the highest in the Mediterranean Sea. With respect to the prediction model, results indicate that benthic habitats play a key role in the spatial distribution of P. nobilis, with higher densities in seagrass meadows of Posidonia oceanica. The fan mussel population density peaked at 9 m depth, decreasing with depth. Also, decreasing densities are expected with increasing exposure to waves. The predicted map shows some hotspots of density different in size and distributed along the MPA, and provides valuable information for the spatial conservation management of this species. Source


Coll J.,Govern de les Illes Balears | Garcia-Rubies A.,CSIC - Center for Advanced Studies of Blanes | Morey G.,Govern de les Illes Balears | Renones O.,Spanish Institute of Oceanography | And 3 more authors.
ICES Journal of Marine Science | Year: 2013

The use of MPAs to recover fish stocks in littoral areas of the western Mediterranean has made it possible to obtain time dataseries on the biomass evolution over the last decade. The biomass of six fully protected MPAs increased between two- and threefold over a period of five years. After this time the biomass remained stable. This pattern allowed us to adjust logistic curves between the biomass and protection time, and to estimate the carrying capacity (K) of each site. In the present study we investigate the relationships between carrying capacity (K) and habitat characteristics at each protected site. The relationships between habitat/environmental variables and K are analysed by applying generalized linear models. Environmental descriptors showing major effects on biomass are related to depth, exposure, rugosity, and offshore slope at different spatial scales. Comparison of observed and predicted values using the model for exploited sites in the Balearic Islands made it possible to determine their conservation status. This empirical approach to the relationships between environmental factors and fish assemblage biomass could constitute a very useful tool when traditional fishery management based on catch and effort data from the artisanal and recreational fleets is difficult to apply. © 2013 © 2013 International Council for the Exploration of the Sea. Published by Oxford University Press. All rights reserved. Source

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