Hydroacoustical evidence of the expansion of pelagic swarms of Munida gregaria (Decapoda, Munididae) in the Beagle Channel and the Argentine Patagonian Shelf, and its relationship with habitat features

MARIANO J. DIEZ; ARIEL G. CABREIRA; ADRIAN MADIROLAS; GUSTAVO A. LOVRICH

JOURNAL OF SEA RESEARCH

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 114 p. 1 - 12

1385-1101

Squat lobsters are highly diversified and widespread decapods, of which only three speciesform pelagic swarms. Here we infer the expansion of Munida gregaria populations in the BeagleChannel and the Argentine Patagonian shelf by means of acoustic surveys of pelagic swarms. Wealso describe the habitat characteristics in which these swarms occur. Acoustic data was collectedduring three multidisciplinary scientific cruises on board of the R/V Puerto Deseado during 2009,2012 and 2014. Despite differences in the environmental conditions between the two surveyedareas, between 2009 and 2014 pelagic swarms increased their occurrence and abundance both inthe Beagle Channel and on the Argentine Patagonian Shelf. Towards the end of the studied period,pelagic swarms of M. gregaria occurred in new locations, supporting the notion of a populationexpansion. Within the Beagle Channel swarm expansions were more marked than on thePatagonian Shelf. We here postulate that M. gregaria expansions occur in association withproductive areas of the Argentine continental shelf, such as frontal zones, favoured by the squatlobster phenotipic plasticity that permit to exploit resources in both the neritic and benthicenvironments. At a regional scale on the Patagonian Shelf, three main groups of pelagic swarms ofMunida gregaria were clearly associated to respective frontal zones. The information presentedhere is necessary to understand fluctuations in both distribution and abundance patterns of a keyspecies on the Argentine Continental Shelf. These fluctuations could be direct or indirect indicatorsof changes in the ecosystem.