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Tuesday, June 5, 2007
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Non-linear response of deep-sea red shrimp (Aristeus antennatus) catches to environmental forcings in a submarine canyon in NW Mediterranean Sea
Nixon Bahamon1, Francesc Sardà1, Joan B. Company1, Jorge Sánchez1, Daniel Orellana1, Johan CoenJaerts2, Daniel Martín2, Diana Zúñiga3, Antoni Calafat3, Mar Flexas4, Grabiel Jordà4, Manuel Espino5, and Joan Puigdefàbregas5. (1) Departament de Recursos Marins Renovables, Institut de Ciències del Mar (CMIMA - CSIC), Passeig Marítim de la Barceloneta 37-49, Barcelona, 08003, Spain, (2) Departament d’Ecologia aquàtica, Centre d'Estudis Avancats de Blanes - CSIC, Carrer d'accés Cala Sant Francesc, 14, Blanes, 17300, Spain, (3) Facultat de Geologia, Dept. Estratigrafia, P. i Geociències Marines, Universitat de Barcelona, C/Martí i Franqués s/n, Barcelona, 08028, Spain, (4) Instituto Mediterráneo de Estudios Avanzados – CSIC, Miguel Marqués 21, Esporles, Islas Baleares, 07190, Spain, (5) Laboratori d'Enginyeria Marítima, Universitat Politècnica de Catalunya, Jordi Girona, 1-3, Campus Nord-UPC, Edif. D-1, Barcelona, 08034, Spain
In the Blanes submarine canyon A. antennatus dominates between 600 - 800 m depth coinciding with the lower boundary of Levantine Intermediate Water (LIW) and the upper boundary of Western Mediterranean Deep Water. The species is highly commercially exploited representing about 25% of total demersal catches. In spite of its economic relevance and recent unexpected sudden reduction of catches along the NW Mediterranean coast, a few studies have provided insights of the environmental conditions forcing the shrimp distribution. Using generalised additive models and regression trees, a time series of daily catches of A. antennatus carried out during a whole year were evaluated in relation to daily averaged values of temperature, salinity, mean kinetic energy (MKE) and eddy kinetic energy (EKE). We found that the relationship between shrimp and water temperature is not significant; the highest catch values take place on relatively saltier waters (between 38.5 38.6) showing small MKE values (between 6 and 9 cm2 s-2) and regular values of EKE (between 10 and 20 cm2 s-2). We conclude that abundance of A. antennatus is non-linearly constrained by the environmental conditions, and under relatively steady temperature values it prefers relatively saltier (LIW) and low-strength waters showing moderate mesoscale variability.