Transgenerational exposure to deoxygenation and warming disrupts mate detection in Gammarus locusta

Ocean deoxygenation and warming have been shown to pose a growing threat to the health of marine organisms and ecosystems. Yet, the potential for acclimation and adaptation remains poorly understood. The aim of this study was to evaluate the effects of transgenerational exposure to reduced oxygen availability and elevated seawater temperature on the chemosensory-dependent mating mechanisms of male amphipods Gammarus locusta. Three subsequent generations were exposed to four experimental treatments for 30 days: 1) present-day scenario, 2) warming; 3) deoxygenation; and 4) warming + deoxygenation. After exposure, the number of individuals that reached adulthood was gauged, and adult males from F0 and F1 were subjected to behavioral trials to assess their capacity of long-distance female cue detection through quantification of response time, the first direction of movement, activity rate, and proportion of time spent in female scent cues. Ocean warming induced mortality, and reduced oxygen availability had adverse effects on each of the investigated behavioral traits, which were amplified when combined with elevated temperature. Still, when compared with F0, the F1 generation demonstrated more adaptability (i.e., higher activity rate and preference for female odors) to the combination of the two stressors, suggesting positive carry-over effects. Nevertheless, full recovery to control levels was not observed. Altogether, this study indicates that future scenarios of ocean deoxygenation and warming have the potential to disrupt chemosensory-dependent mate detection in amphipods, but also suggests possible behavioral adaptations. We call for greater research efforts on long-term impacts of ocean change on the behavioral and physiological processes of benthic coastal communities.