Macroscale abundance patterns of hydromedusae in the temperate Southwestern Atlantic (27°–56° S)

Abstract

Gelatinous organisms are crucial components of marine ecosystems and some species imply social and economic consequences. However, certain geographic areas, such as the temperate Southwestern Atlantic (SWA, 27° - 56° S), remain understudied in terms of jellyfish ecological data. We analyzed 3,727 plankton samples collected along ~6.7 million km 2 over a 31-year period (1983–2014) to determine the occurrence, abundance, and diversity patterns of hydromedusae in the SWA. Analyses were made at both community and species levels. Two abundance hot spots of hydromedusae were identified, where values up to 2,480 ind. m -3 were recorded between 2003 and 2014. Liriope tetraphylla and Obelia spp. were the main responsible for recurrent peaks. Diversity indexes were in the range of those published for temperate areas worldwide, and some coastal zones showed values that can be considered moderate to high for a temperate neritic region. The community analysis yielded 10 groups following previously determined biogeographic schemes throughout the study area. This work enhances the knowledge of hydromedusae in the SWA and provides essential information about the current global warming context and the gelatinous zooplankton data necessity.

First record of the non-native medusa Blackfordia virginica (Hydrozoa, Leptomedusae) on the coast of Uruguay, Southwestern Atlantic

“…Also, shelf currents and the estuarine plume of Rio de la Plata, which reaches this part of the coast (Moreira & Simionato 2019), may favour the arrival of invasive species found in nearby ecosystems. Blackfordia virginica has invaded tropical and subtropical estuaries in the SW Atlantic (Freire et al 2014), and our observations suggest it has now been successfully introduced to the Río de la Plata region, following the first recorded instances in Argentinean waters in 2000 (Genzano et al, 2006(Dutto et al, 2019.…”

A global record of particulated metals on the southwestern Atlantic shelf (Argentine Sea)

“…The zooplankton community shows a high abundance of calanoid copepods, chaetognaths, salps and hydromedusa (Heileman 2009;Dutto et al 2019). Also, the PSLME supports significant seabirds and marine mammals communities as well as invertebrates and is particularly rich in fisheries resources (Favero et al 2003;Veit 2008;Elías et al 2011;Mandiola et al 2015;Bigatti and Signorelli 2018).…”