Abstract
Decapod crustacean fisheries play a crucial role on the northwestern Mediterranean coast due to their high commercial value. Although knowledge of larval ecology and recruitment dynamics of these species is essential to establish a sustainable fisheries management, they are still poorly known. In this paper, we describe the composition, abundance and distribution of decapod crustacean larvae in the submarine canyon off Blanes (northwestern Mediterranean Sea) during summer thermal stratification conditions. Samples were collected in September 2011 with a multi-net system and a 60-cm bongo net at 22 stations with bottom depths of between 100 and 1800 m. A total of 635 larvae from 60 genera were identified. The most relevant taxa were Aristeus antennatus (7.93 individuals/1000 m3), the family Sergestidae (7.24) and Alpheus glaber (6.78). These three taxa were dominant ( > 20% of total decapod larvae) at more than half of the stations. Decapod larval communities were found to be richer and more diverse at the canyon head, a finding which could be explained by the higher retention rates when compared with the upstream and downstream walls and the canyon axis.
Highlights
Submarine canyons are known to be hotspots for biodiversity (Gili et al 2000, De Leo et al 2010)
A total of 635 decapod larvae belonging to 66 taxa were sorted, and 426 of them were identified at least to the genus level by morphological characters
Molecular analyses were used to discriminate between PZI larvae of A. antennatus and G. elegans
Summary
Submarine canyons are known to be hotspots for biodiversity (Gili et al 2000, De Leo et al 2010). Their geomorphology shapes the sediment transport patterns on the continental margin, enhancing productivity as they play the role of particulate and organic matter traps (Granata et al 1999) Previous studies on such structures have shown that particles from shallow coastal adjacent areas can be transported into the greater depths of the canyon axis, where they sink to the bottom due to reduced horizontal advection and higher residence time (Ahumada-Sempoal et al 2015). The western Mediterranean continental margin is cut by several submarine canyons, some of which have been thoroughly studied from a fisheries management perspective These canyons are important fishing grounds for many fish and crustacean species of both ecological and commercial interest, which use these areas as spawning, nursery or recruitment zones (Sardà et al 2009, Fernandez-Arcaya et al 2013). The deep-sea blue and red shrimp Aristeus antennatus, targeted by the bottom-trawling fleet in the submarine canyon areas, can account for up to 50% of the fishermen’s associations annual revenue and is subject to a local management plan in the area of Palamós, north of Blanes (BOE 2018)
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