FISH ASSEMBLAGE AND DYNAMICS ON TWO ARTIFICIAL REEFS IN THE SOUTH OF THE BAY OF BISCAY (FRANCE). Iker CASTEGE1*, Emilie MILON1, Gérard FOURNEAU2, Alain TAUZIA3. 1
Centre de la mer de Biarritz, Plateau de l'Atalaye, 64200 Biarritz 2 Aquitaine Landes Récifs (ALR), 501 Route de Lestrilles, 40990 Saint Paul Lès Dax 3 Association pour la Défense, la Recherche et les Études Marines de la Côte d'Aquitaine (ADREMCA), 57 rue du pignada 40200 Mimizan *Corresponding author:
[email protected] ©ALR
Background This study focuses on 2 main artificial reefs localised along French Atlantic coast (in Aquitania) at Mimizan (“Porto” artificial reef) and Capbreton. Theses AR are managed by 2 associations : ADREMCA and ALR.
©ADREMCA
©ALR
Method
“Typi ” unit
Since 2009 both sites are monitored by visual censues, based on a standardized protocol adapted from Bohnsack&Bannerot (1986). Sampling points are placed on different subtrats according to the site: barge, concrete pipe, “Typi” unit (designed and built by ALR).
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Cumulative species richness
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1/ Temporal variation in the “Typi” unit population structure: pelagic fishes were gradually replaced by benthic fauna.
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Capbreton artificial reef
2/ Strong correlation between age of the “Typi” unit and cumulate species richness that highlights the dynamic of the reef. Capbreton AR: Typi unit
R²= 0.887567817121818 0
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Days for flooding
Temporal variation of community structure among years revealed by Correspondence Analysis (matrix 4 years * 43 species (presence/absence)). Axis 1 and axis 2 plan.
Mimizan “ Porto ” site
Relationships between cumulative species richness and the age of the “ Typi ” unit. Regression line and R² are indicated.
Discussion
Specific richness gradient between sampling points: the barge Both site share similar community structure dominated by (SP1) has more important diversity than concrete clusters. benthic fauna and a pool of common species in same abundance (Trachurus trachurus, Umbrina sp, Trisopterus luscus, Conger conger, Bleniidae). Despite this common species each site has its own dynamic and species linked to its particularities. These first results indicate the importance of each site and their complementarity.
Variation in species richness on sampling points (“Porto” site; Mimizan). The vertical arrow indicates standard deviation.
