Spatial and depth-associated distribution patterns of shallow gorgonians in the Algarve coast (Portugal, NE Atlantic)
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ORIGINAL ARTICLE
Spatial and depth-associated distribution patterns of shallow gorgonians in the Algarve coast (Portugal, NE Atlantic) Joa˜o Cu´rdia • Pedro Monteiro • Carlos M. L. Afonso Miguel N. Santos • Marina R. Cunha • Jorge M. S. Gonc¸alves
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Received: 5 March 2012 / Revised: 24 October 2012 / Accepted: 2 November 2012 / Published online: 8 December 2012 Ó Springer-Verlag Berlin Heidelberg and AWI 2012
Abstract The ecological role of gorgonians for marine rocky bottoms is worldwide recognized, but the information on the distribution patterns of NE Atlantic temperate species is insufficient, considering current global, regional and local threats. To overcome the lack of information on the spatial distribution patterns of gorgonians in south Portugal, in 2009/2010, the occurrence and abundance of gorgonian species in rocky bottoms were quantified over more than 25 km of coast (37.1°N/8.6°W) down to 30 m depth. Eunicella labiata, Eunicella gazella, Eunicella verrucosa and Leptogorgia sarmentosa were abundant and frequent in the studied area, while Leptogorgia lusitanica was less abundant. All species evidenced a similar depth pattern, that is abundance significantly increased with depth below 15 m. At shallower waters (up to 15 m), the distribution of gorgonians may be constrained by abiotic factors and competition with algae. Indeed, the abundance of gorgonians was negatively correlated with the percentage cover of algae along the depth gradient, but gorgonians and sponges coexist. Competition among gorgonian species also seems to be low in this area because of the similarity in the abundance pattern observed for the most Communicated by H.-D. Franke. J. Cu´rdia (&) M. N. Santos Instituto Portugueˆs do Mar e da Atmosfera (IPMA), Av. 5 Outubro, s/n, 8700–305 Olha˜o, Portugal e-mail: [email protected] J. Cu´rdia M. R. Cunha CESAM & Departamento de Biologia, Universidade de Aveiro, Campus Universita´rio de Santiago, 3810–193 Aveiro, Portugal P. Monteiro C. M. L. Afonso J. M. S. Gonc¸alves Centre of Marine Sciences (CCMAR/CIMAR), Universidade do Algarve, Campus de Gambelas, 8005–139 Faro, Portugal
abundant species and also their high association. In NE Atlantic shallow temperate rocky bottoms, the distribution of gorgonians seems to be influenced by environmental factors and biological interactions, namely competition (algae) and coexistence (sponges and other gorgonians). Keywords Gorgonians Leptogorgia Eunicella Spatial distribution Rocky bottoms Biological interactions
Introduction Gorgonians (Octocorallia: Alcyonacea) are colonial organisms characterized by a skeleton, slow growth and long life span. Their three-dimensional structure may modify the physical habitat, by reducing current velocity, stabilizing soft substrata, enhancing sedimentation and local accumulation of fine particles, as well as increasing availability of niches similarly to what is found for other marine animals (e.g. Idjadi and Edmunds 2006; Norling and Kautsky 2007). They are habitat formers (foundation species) facil
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