Classifying southern stingray activity states across abiotic factors in Belize coral reef ecosystems

Elasmobranchs often exhibit nocturnal or crepuscular activity, with shark diel patterns being better understood than ray diel patterns. We used accelerometry and hidden Markov models (HMMs) to classify female southern stingray (Hypanus americanus Hildebrand & Schroeder, 1928) activity states across diel periods and environmental conditions in Belize. Three state (low, medium, and high activity) HMMs were constructed for all individuals together and separately (N = 9). Combined, stingrays were most likely to be highly active at night and in low and medium activity states in the morning. However, there was individual variation in diel activity. In contrast, all stingrays consistently used shallow water (< 4 m) during periods of high activity. Temperature had less influence on activity patterns, although three individuals exhibited high activity in cooler water. Generally, high stingray activity was driven by diel cycles and depth. Future research should link activity states to specific behaviours, include a larger sample size, extend tag deployment durations, and explore the impact of predator and prey dynamics on stingray activity.