Living at depth: ecophysiological condition of Boreomysis arctica in autumn and winter in the St. Lawrence estuary and gulf

TL;DR

This study examines the energy condition and feeding habits of Boreomysis arctica in the St. Lawrence system during autumn and winter.

Contribution

The study reveals seasonal and spatial variations in the body condition and trophic behavior of a deep-dwelling mysid species.

Findings

Winter lipid content in B. arctica was higher than in autumn, with wax esters as the main component.

B. arctica showed carnivorous behavior in autumn and omnivorous behavior in winter.

High intra-specific variability in feeding and energy strategies was observed, suggesting opportunistic feeding.

Abstract

Mysids, besides krill, play a significant role in energy transfer and carbon sequestration. The ecology of coastal species is better understood than that of deep dwelling species such as Boreomysis arctica. The objectives of this study were to quantify spatiotemporal variations in body condition and the trophic level of B. arctica in autumn and winter, under sea-ice conditions in the St. Lawrence system, using a multimarker approach. We sampled along a 1000 km transect. Mean abundances in winter were higher in the estuary compared to the Gulf of St. Lawrence. Body condition, measured as total lipid content, was higher in winter than in autumn. Lipids of B. arctica were mainly composed of wax esters, thereby B. arctica is richer in energetic lipids compared to the three dominant krill species. We also observed seasonal differences in the trophic level of B. arctica, revealing carnivorous behavior in autumn compared to omnivory in winter. High intra-specific variability in both energetic strategy and feeding behavior was found that is potentially due to opportunistic feeding. Energy rich reserves suggest that B. arctica could act as a valuable prey for both benthic and pelagic consumers and thus playing a key role in bentho-pelagic energy transfer.

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