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Volume 44 - Number 2 - 2009
Artículo


The sea urchin Diadema antillarum Phillipi, 1845 influences the diversity and composition of the mobile mega-invertebrate community on rocky bottoms off the Canary Archipelago

Leonor Ortega1, Fernando Tuya2,3 y Ricardo J. Haroun1

 

1Grupo de Biodiversidad y Gestión Ambiental (BIOGES), Facultad Ciencias Mar, Universidad de Las Palmas de Gran Canaria, 35017, Las Palmas de Gran Canaria, Islas Canarias, España
2CIIMAR, Rua dos Bragas 289, 450-123 Porto, Portugal
3Center for Ecosystem Management, Edith Cowan University, Joondalup Drive, 6027 Joondalup, WA, Australia

 

E-mail: leonor129@gmail.com

 

The effect of the sea urchin Diadema antillarum density over the diversity and composition of the mobile mega-invertebrate community (> 2 cm) inhabiting shallow rocky reefs off the Canary Archipelago (eastern Atlantic) is described. Specifically, it was predicted that (1) high densities of D. antillarum produce a low diversity of the mobile mega-invertebrate community, and (2) the composition of this community changes between rocky bottoms (= reefs) under different densities of D. antillarum. The presence of mega-invertebrate taxa, and the density of D. antillarum individuals were recorded visually using 2 x 2 m quadrats (n = 16 replicates) in each of 24 locations (three locations in each of the eight main islands of the archipelago), which were visited in four occasions between February-2003 and October-2004. Thrity-three taxa of mobile mega-invertebrates were observed. We registered a decline in the richness of such assemblages with increasing densities of D. antillarum (rs = -0.20; P<0.001). Species richness fluctuated considerably (0-16 species) in those locations with low densities of D. antillarum (< 2 ind. m-2). However, species richness was always low (< 9 species) in those locations with high densities of D. antillarum (> 8 ind. m-2). A CAP ordination analysis showed significant differences in the composition of the mega-invertebrate community between rocky bottoms under different densities of D. antillarum, and we registered a negative correlation between the presence of some taxa and the densities of sea urchin. Consequently, the sea urchin D. antillarum influences the diversity and composition of the mobile mega-invertebrate community on rocky bottoms off the Canary Archipelago

 

Key words: Echinoderms, community ecology, Canary Islands

 

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1Laboratorio de Zooplancton, Instituto de Ciencias del Mar y Limnología,Universidad Nacional Autónoma de México. A. P. 70-305, 04510 México, D. F. México
 
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