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La Palma del Condado, Spain

Sangil C.,Area de Biodiversidad | Sangil C.,University of La Laguna | Sanson M.,University of La Laguna | Afonso-Carrillo J.,University of La Laguna | And 4 more authors.
Marine Environmental Research | Year: 2012

The present work analysed the main changes in subtidal algal assemblages in the last decade in an oceanic archipelago (Canary Islands - eastern Atlantic Ocean). Changes result from increases in cover of ephemeral benthic algae, such as the non-native chlorophyte Pseudotetraspora marina and the native cyanophytes Blennothrix lyngbyacea, Schizothrix calcicola and Schizothrix mexicana. Ephemeral algae overgrow subtidal assemblages which are extensively dominated by Lobophora variegata, but competitively do not exclude other species. Increases in the abundance of species coincided with a warming of about 2 °C in surface seawater temperature (SST) linked to the weakening of the Cold Canary Current and the Northwestern African upwelling. Shifts in the distribution and cover of ephemeral species follow the SST gradient from warmer waters in the western islands to colder waters in the eastern ones. While in the warmest western islands, species have spread quickly colonizing all type of substrates in just a few years (2005-2008), the occurrence of ephemerals towards the coldest eastern islands is yet inconspicuous. © 2012 Elsevier Ltd.

Sangil C.,Area de Biodiversidad | Sangil C.,University of La Laguna | Clemente S.,University of La Laguna | Martin-Garcia L.,Area de Biodiversidad | And 2 more authors.
Estuarine, Coastal and Shelf Science | Year: 2012

Rapid declines in the sea urchin Diadema aff. antillarum densities and shifts in community states of sublittoral rocky reefs have been observed over a short period (between 2004 and 2008) for the first time in an area with fishing restrictions (the MPA of La Palma, Canary Islands, eastern Atlantic Ocean). Changes were spatially variable according to the MPA's use area considered. During this period there was a sea urchin density reduction (in some cases from 3.34 to 0.45 indv·m-2), and an increase of erect seaweed (up to 30% of cover) in the sites of the no-take area. In the partially restricted fishing area, the effect was less clear and only some sites, near to the no-take area, showed the sea urchin reduction and seaweed growth, in contrast to the increase of sea urchin densities outside the MPA. In addition to increased coverage, there was also a replacement of the ephemeral species by the perennial seaweed Lobophora variegata. These changes were related to increases in the abundance of fish predators of the sea urchins. In the no-take area, where there is total fishing restriction, predators were so abundant to induce shifts in the benthic community, while in the partially protected area such as outside the MPA, fishing prevented the top-down process and the changes in the communities. © 2012 Elsevier Ltd.

Lopez C.,University of La Laguna | Poladura A.,University of La Laguna | Hernandez J.C.,University of La Laguna | Martin L.,Area de Biodiversidad | And 3 more authors.
Scientia Marina | Year: 2012

This study aimed to evaluate the effects of protection from extractive activities on the population structure of two limpets of commercial interest, Patella ulyssiponensis and Patella candei crenata. We evaluated the status of these populations in La Palma Marine Protected Area (MPA), Canary Islands, and in comparable unprotected areas in the lower intertidal zone of the same island. We showed that the density of P. ulyssiponensis depended greatly on the level of protection, whereas the effects of protection on the density of P. candei crenata were less clear and only differences between sites were found. These results are probably linked to the different habitat affinities of the two species studied and demonstrate the need to tailor conservation strategies in MPAs to individual species for appropriate management of local shellfish resources.

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