Outbreak of a neurotoxic side-gilled sea slug (Pleurobranchaea sp.) in Argentinian coasts

Abstract

Since 2009 we have been registering the outbreak of an unknown side-gilled sea slug of the genus Pleurobranchaea in coastal waters of Argentina, southwestern Atlantic Ocean. Examination of both external macroscopic features and internal structures via electron microscopy did not allow us to conclusively identify the species. Nevertheless, since Argentinian specimens closely resemble Pleurobranchaea maculata (a species native from Australia and New Zealand known to contain a potent neurotoxin) we performed a bioassay in our specimens, which was positive for neurotoxins. The presence of this pleurobranch in Argentinian waters is of concern beyond the ecological effects of the outbreak of a marine predator and requires urgent attention. This work provides a guide to distinguish between this unidentified species and the sympatric cryptogenic Pleurobranchaea inconspicua, based on features that are readily observable in fresh and preserved specimens. We discuss the potential effects of this outbreak on local communities.

Growth pattern and changes in abundance of the endangered bat star Asterina stellifera

“…; Farias et al . ). These facts together set a concerning scenario for its conservation, with possible impacts at the community level considering the importance that A. stellifera has as a predator of a wide variety of benthic organisms (Farias et al .…”

“…) and grey sea slug P. maculata (Farias et al . ). Thus, this work provides crucial baseline information for further assessments of the effect of these invasive species on A. stellifera .…”

“…) and the sea slug Pleurobranchaea mac11ulata (Farias et al . ) add potential threats to this A. stellifera population. The algae U. pinnatifida competes for space and often displaces many benthic species (Casas et al .…”

“…The accelerating development of Mar del Plata's shoreline for industry, agriculture and tourism during the last decade (Boschi 2004;Isla 2004) is degrading coastal ecosystems by habitat disturbance and pollution (Orensanz et al 2002;Albano et al 2013). Moreover, the recent arrival in the area of two invasive species, the kelp Undaria pinnatifida ) and the sea slug Pleurobranchaea mac11ulata (Farias et al 2015) add potential threats to this A. stellifera population. The algae U. pinnatifida competes for space and often displaces many benthic species (Casas et al 2004;Farias et al 2012;Meretta 2014) that are important prey items of A. stellifera while P. maculata is a voracious predator whose diet widely overlaps that of this sea star (Meretta 2014).…”

“…The aim of this study was to survey the growth rates of A. stellifera individuals in the only place where it is still abundant and to assess the relationship among changes in local abundance and variations in selected intrinsic (gonadal stage) and extrinsic (water temperature and salinity, rainfall) factors. To this end, we used a monthly data set covering 5 years prior to the arrival of the invasive kelp U. pinnatifida ) and grey sea slug P. maculata (Farias et al 2015). Thus, this work provides crucial baseline information for further assessments of the effect of these invasive species on A. stellifera.…”