Could human activities be affecting Munida gregaria larval distribution along the Beagle Channel, Tierra del Fuego, Argentina?

CAPITANIO, FABIANA L.; XAUS, LUCILA; PRESTA, MARÍA LAURA

Toronto

Encuentro; SETAC North America 40th Annual Meeting; 2019

Society of Environmental Toxicology and Chemistry (SETAC)

Munida gregaria - the squat lobster - has been subject of numerous studies during the past 20 years. In the last decade their density has increased dramatically, becoming one of the most abundant decapod species in the Southwestern Atlantic Ocean. By feeding upon algae, detritus and sediment and particulate organic matter and being prey of many top predators, this species represents a trophic shortcut in the marine food web. The squat lobster exhibits phenotypic plasticity that allows it to exploit resources in both the neritic and benthic environments. Here, we analysed the spatio-temporal variations in M. gregaria larvae by means of samples collected seasonally at the coastal and external zones of Ushuaia Bay (inner Beagle Channel), the former one being highly impaired by urban discharges. Also, we provide baseline data regarding the abundance of M. gregaria larvae along the Beagle Channel, including the inner and outer sectors, during the springtime of 2014 and 2015. Results from 2012 showed the highest zoeae abundances during late winter (September) (8.46 ind.m3) coinciding with maximum values of salinity and chlorophyll-a. Mean abundance of larvae was similar between the coastal and external zones of the bay; except in late winter, when larvae were more abundant at the external zone. In regards to the spatial distribution of M. gregaria larvae along the Beagle Channel, highest larval abundances were found at the outer sector during both years. Previous experimental studies in Ushuaia Bay have reported that,crustacean larvae can suffer inhibition in the moulting process and anomalies in the swimming behaviour caused by petroleum hydrocarbons and heavy metals, ,two contaminant present in the coastal zone of this bay. Considering that there is little knowledge on the sensitivity of M. gregaria larval stages to aquatic contaminants, we recommend further experimental and field studies about the potential effects of human activities on this species in order to better understand the spatial patterns observed in this study.