LE3 .A278 2020

2020

Currie, Suzie

Acadia University

Bachelor of Science

Honours

Biology

Biology

As climate warming progresses, aquatic species are at risk if they cannot adapt to their new, warmer reality. We know tropical species are more vulnerable to climate warming than their temperate counterparts because their physiological thermal limits are perilously close to their environmental temperature. Living this close to one’s thermal limits results in a narrower thermal safety margin (TSM), which can impact species fitness. Notably, a fish’s social environment may influence how it responds to high temperature. Using an amphibious tropical fish, the mangrove rivulus, I hypothesized that sociability would negatively affect physiological and behavioural responses to increasing water temperatures. I used four distinct social situations: (1) a fish in isolation (control), (2) pairs, (3) groups of three, and (4) an isolated fish with a mirror. I measured the temperature at which fish emerged from heated water and their thermal tolerance (critical thermal maximum). I predicted that fish in social environments (i.e. mirror, pairs and threes) would emerge from water at a higher temperature, closer to their thermal limits, compared to isolated fish. My results showed that fish socially stimulated with their mirror reflection, had the highest emersion temperature compared to all groups, but that fish in pairs, had the widest TSM. This finding suggests that paired fish may be at a thermal advantage compared to other groups. Furthermore, I discovered a correlation between higher emersion temperature and an increase of approaches, as well as a correlation between a lower TSM and increase of approaches. Overall, my findings suggest there may be a relationship between bolder fish engaging in more social stimulation, resulting in a narrower TSM for these fish, but further examination is needed to confirm this relationship. This study gives some insight into how social stimulation can affect a rivulus’ response to ecologically relevant warming temperatures. This information is crucial for the conservation of species living close to their thermal optimum.

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https://scholar.acadiau.ca/islandora/object/theses:3410