Subantarctic Front variability: a potential driver of Patagonian scallop Zygochlamys patagonica recruitment fluctuations

The Patagonian scallop Zygochlamys patagonica sustains an important economic resource in the Southwestern Atlantic Ocean and presents recruitment variability in beds associated with the shelf break front. The aim of this study was to analyze the environmental drivers acting on recruits that may cause large population abundance fluctuations on interannual timescales. Scallop recruitment data from 2000 to 2007 were analyzed alongside oceanographic variables from remote sensing and bottom temperature measurements from surveys. A statistically significant correlation was identified between interannual recruitment variability and the northernmost latitude of the Subantarctic Front (SAF) (catch per unit effort vs. SAF position, r = 0.81, p < 0.05). When the SAF displaces northwards, bottom temperature is lower, and recruitment is enhanced as larvae have more time to develop and more chances to avoid advection to the open ocean. Conversely, if the SAF displaces southward, recruitment is negatively affected because the larvae do not have enough time to settle before being exported to the oceanic realm. Results are discussed considering the planktonic larval duration, larval depth distribution, connection between beds, bottom temperature variability, and the SAF latitudinal position and its role as the northern population boundary. Potential impacts of climate change on recruitment dynamics are also discussed.