Abstract
Dynamics of biological processes on the deep-sea floor are traditionally thought to be controlled by vertical sinking of particles from the euphotic zone at a seasonal scale. However, little is known about the influence of lateral particle transport from continental margins to deep-sea ecosystems. To address this question, we report here how the formation of dense shelf waters and their subsequent downslope cascade, a climate induced phenomenon, affects the population of the deep-sea shrimp Aristeus antennatus. We found evidence that strong currents associated with intense cascading events correlates with the disappearance of this species from its fishing grounds, producing a temporary fishery collapse. Despite this initial negative effect, landings increase between 3 and 5 years after these major events, preceded by an increase of juveniles. The transport of particulate organic matter associated with cascading appears to enhance the recruitment of this deep-sea living resource, apparently mitigating the general trend of overexploitation. Because cascade of dense water from continental shelves is a global phenomenon, we anticipate that its influence on deep-sea ecosystems and fisheries worldwide should be larger than previously thought.
Highlights
Vertical, often seasonal, sinking of organic material is widely accepted as the main source of nutrients to the deep-sea floor [1,2,3]
During the 2005 cascading event, downslope currents associated with the propagation of dense, cold and turbid shelf waters reached speeds .85 cm s21 inside submarine canyons of the northwestern Mediterranean (Figure 2A–2C)
It is true that the disappearance of Aristeus antennatus from the fishing grounds leads to a temporary reduction of the real fishing effort of this monospecific fishery, but only as long as this species does not return to these grounds
Summary
Often seasonal, sinking of organic material is widely accepted as the main source of nutrients to the deep-sea floor [1,2,3]. Previous intense cascading events of dense shelf waters (i.e. those reaching the deep basin) were identified after the analysis of historical hydrographic data and occurred in 1971, 1980, 1988 and 1999 [37], occurring at a decadal time-scale.
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