The effect of habitat complexity on temperature preference in coral reef fish.

Ms Tiffany Nay1, Dr.  Andrew Hoey1, Dr. Jodie Rummer1, Prof. John Steffensen2, Dr. Jacob Johansen3

1ARC CoE Coral Reef Studies, James Cook University, Townsville, Australia, 2University of Copenhagen, Helsingør, Denmark, 3New York University-Abu Dhabi, Abu Dhabi, United Arab Emirates

Global temperatures are becoming more extreme, posing a challenge to ectothermic species. Many ectotherms utilize thermoregulation as a strategy to regulate body temperature within preferred habitats. However, as habitat degradation and warming escalate worldwide, it is crucial to understand the trade-offs between habitat and thermal preference. While numerous studies have investigated the effects of temperature and habitat independently, how habitat selection is affected by thermal preference is unknown. Here we investigated if habitat complexity influenced the thermal preference of a common coral reef damselfish, the black-axil chromis, Chromis atripectoralis. A shuttlebox system that allowed the fish to move freely between warm and cold chambers was used to establish the preferred temperature of each individual. When chambers remained empty of habitat structure or when complex habitat structure was placed in the warm chamber and degraded habitat in the cold chamber, fish preferred ~28°C. When complex habitat was placed into the cold chamber and degraded habitat in the warm chamber, fish preferred ~19°C. Within the average range of temperatures for coral reefs (17-29°C), fish preferred to remain within a complex habitat structure; however, when water temperatures surpassed this range, fish resorted to leaving their habitat and seek out areas with more benign water temperature. Within normal ranges of temperatures seen on coral reefs, some fish species may choose to remain with habitat structure, but as temperatures are predicted to increase, some species may prioritize thermal use over habitat preferences and are therefore likely to migrate altering community compositions around the world.


Tiffany Nay is a PhD candidate from the ARC Centre of Excellence for Coral Reef Studies at James Cook University in Townsville, Queensland, Australia. My current research interests focus on the use of movement to alleviate the negative effects of ocean warming, establishing preferred temperatures of tropical species, and what other factors may influence an individual’s thermal preference, such as the thermal variability of the fishes natural environment, habitat structure, and the effects of potential competitors and predators.

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