Limited capacity for developmental thermal acclimation in three tropical wrasses

Abstract

For effective conservation and management of marine systems it is essential that we understand the biological impacts of and capacity for acclimation to increased ocean temperatures. This study investigated for the first time, the effects of developing in projected warmer ocean conditions in the tropical wrasse species: Halichoeres melanurus, Halichoeres miniatus and Thalassoma amblycephalum. New recruits were reared for 11 weeks in control (29 °C) and +2 °C (31 °C) temperature treatments, consistent with predicted increases in sea surface temperature for the end of the century. A broad range of key attributes and performance parameters were tested, including aerobic metabolism, swimming ability, burst escape performance and physical condition. Response latency of burst performance was the only performance parameter in which evidence of beneficial thermal developmental acclimation was found, observed only in H. melanurus. Generally, development in the +2 °C treatment came at a significant cost to all species, resulting in reduced growth, condition and reduced metabolic and swimming performance relative to controls. Development in +2 °C conditions exacerbated the effects of warming on aerobic metabolism and swimming ability, compared to short-term warming effects. Burst escape performance parameters were only mildly affected by development in the warmer treatment, with non-locomotor performance (response latency) showing a greater thermal sensitivity than locomotor performance parameters. Overall these results indicate that the effects of future climate change to tropical wrasses would be underestimated with short-term testing. This study highlights the importance of holistic, longer-term developmental experimental approaches, with warming found to yield significant, species-specific responses in all parameters tested