Investigation of the impacts of singular and coinciding acute climate stressors on the nutritional quality of the pteropod Limacina helicina, a juvenile Pacific salmon dietary species
PSSI Project Summary
Division: Ecosystem Sciences (ESD)
Section: Nearshore Ecosystems
Organization: DFO
Session(s): Marine Stressors
Presentation Date(s): December 04, 2025
Speakers: Chris Pearce
Abstract:
Under global climate change, co-occurrence of gradual physico-chemical changes in seawater and extreme events poses a substantial threat to marine ecosystems. The present study focused on the Northeast Pacific coastal region where coinciding rises in mean seasonal seawater temperatures and increasingly prevalent acute stressor events, such as heatwaves and low-pH upwellings, are occurring. Limacina helicina, a cold-water pteropod species of high abundance within the region’s zooplankton communities, is highly susceptible to climate change stressors, with documented impacts of ocean warming and acidification, including altered shell development, growth, and survival. To date, however, there has been minimal investigation of climate change effects on the species’ nutritional status under regionally-relevant conditions, thereby contributing to a continued lack of understanding of how climate change impacts at lower trophic levels may relay across wider ecosystems. To begin to address this, we examined the survival and fatty acid profile of L. helicina under future conditions via a laboratory experiment during which pteropods were exposed to singular and coinciding warming (mean summer seawater temperature + 4°C) and low-pH (~1500 ppm pCO2; Ωarag = 0.53) conditions, with fatty acid analyses carried out via gas chromatography at 48-h and 5-d timepoints. Results indicated a significant impact of pCO2 on pteropod nutritional status at 48 h and a significant impact of temperature on survival at 5 d. Additionally, fatty acid analyses of historical plankton samples, collected in the region over 2014–2023, were carried out to examine time-series changes in pteropod fatty acid profiles in relation to temperature records. Results indicated significant differences in a number of fatty acid fractions between year groups, and in the overall fatty acid profiles of a number of year groups (2016 and 2019; 2018 and 2021), the latter findings parallelled by minor to moderate divergences in seasonal temperature conditions. Overall, findings suggest that short-term low-pH upwelling events and, to a lesser degree, changing seawater temperature conditions may result in altered fatty acid composition in pteropods, potentially leading to shifts in nutritional quality and associated impacts on trophic energy transfer.