Pelagic swarms and beach strandings of the squat lobster Munida gregaria (Anomura: Munididae) in the Beagle Channel, Tierra del Fuego

Abstract

The present article is the first formal record of pelagic swarms and beach strandings of the squat lobster Munida gregaria in the Beagle Channel, southern South America. To describe size composition and natural diet of beach strandings and swarms, samples from strandings were taken surveys were carried out to describe both, horizontal distribution and school metrics of swarms. Pelagic swarms and beach strandings were composed of 100% individuals of the morph gregaria of M. gregaria. Mean size of males and females in both, beach strandings and swarms, were similar. The diet of pelagic M. gregaria was composed mainly of crustaceans, unicellular algae and small macroalgae, sediment and particulate organic matter. Swarms of pelagic Munida took the shape of extended layers of varying density and height. Their positions in the water column were also variable: swarms were found at different depths, from the subsurface layer to near the sea bottom. Occasionally, some large swarms occupied most of the water column. In the Beagle Channel, SW winds during spring tides could be a forcing factor for M. gregaria strandings. The absence of shoaling animals in the Beagle Channel between 1997 and 2002 and the recent occurrence of swarms are coincident with their appearance in other locations in Patagonia. In consequence, we hypothesize that the factor influencing the formation of swarms must be acting at a regional scale.

Adaptation of diet in a changed environment: Increased consumption of lobster krill Munida gregaria (Fabricius, 1793) by Argentine hake

“…Munida gregaria usually exhibits high abundances in Southern Chile and Argentina in the Drake Passage and Beagle Channel (Diez et al., ; Pérez‐Barros, Tapella, Romero, Calcagno, & Lovrich, ). During the past decade scientists have started to examine the ecological role of these abundant organisms in an effort to take a more integrated ecosystem approach to fisheries management (Lovrich & Thiel, ).…”

“…The former is supported by the Patagonian current, a diluted plume that occurs with an excess of rainfall in the Southeast Pacific and the continental discharge along the west coast of South America (Acha et al., ), which transports low salinity waters, mixed by tides and winds, 800 km northwards along the west coast of South America from the Drake Passage to the southern limit of the SJG (Acha et al., ). Munida gregaria can remain pelagic after metamorphosis for up to 6 months; adults are benthic but can perform vertical migrations into the water layer (Diez et al., ; Zeldis, ), which would facilitate transport from the Beagle Channel to the frontal and highly productive region of the Southern SJG ecosystem. However, further studies considering oceanographic and environmental variables are necessary in order to explain the geographic expansion of Mu.…”

“…2013 2014 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 0 5 10 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 0 5 10 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 from the Drake Passage to the southern limit of the SJG (Acha et al, 2004). Munida gregaria can remain pelagic after metamorphosis for up to 6 months; adults are benthic but can perform vertical migrations into the water layer (Diez et al, 2012;Zeldis, 1985), which would fa- populations were strongly inversely related to predator abundance (Worm & Myers, 2003). Varisco et al (2015) (Sánchez & Prenski, 1996).…”

DNA Metabarcoding as a Marine Conservation and Management Tool: A Circumpolar Examination of Fishery Discards in the Diet of Threatened Albatrosses

“…There was an unidentified clupeid in the diet at Diego Ramirez in (Arata and Xavier, 2003, and a small unidentified fish at New Island in 1987 that made up 80% of the fish prey (Thompson, 1992), which may have been sprat. This species has a high biomass across the southern Patagonian shelf as far as the Magellan Strait (Sánchez et al, 1995), Chilean channel waters (Diez et al, 2012) and around the Falkland Islands (Agnew, 2002), and is common in the diet of other seabirds and The hierarchical clustering of albatross diet and fishery catch data by month, based on the proportion of sequences (RRA, black text) and proportion of catch (blue text). Clusters were based on dissimilarity indices calculated with the Manhattan method, and hierarchical clustering was constructed using the average agglomeration method (note low sample sizes during January 2014 and 2015).…”

Biología de <i>Munida gregaria</i> (Crustacea: Anomura): bases para su aprovechamiento pesquero en el Golfo San Jorge, Argentina

“…La mayoría de los integrantes de la familia son especies bentónicas; sólo dos presentan hábitos pelágicos en fases postlarvales: Pleuroncodes planipes Stimpson 1860 y Munida gregaria (Fabricius 1793). Agregaciones pelágicas de estas especies han sido consignadas por numerosos autores (Thomson 1898, Chilton 1909, Matthews 1932, Boyd 1967, Kawamura 1976, Williams 1980, Zeldis 1985, Aurioles-Gamboa 1995, Varisco y Vinuesa 2010, Diez et al 2012.…”