Physiological and biochemical thermal stress response of the intertidal rock goby Gobius paganellus

Abstract

The intertidal habitat is characterized by environmental conditions with steep gradients. Thus, inhabiting communities have long served as models in stress research. Moreover, several studies have reported their vulnerability to climate change and consequent distribution shifts (up to 50km per decade) and abundance changes. The aims of this study were to test the effects of temperature on the rock goby Gobius paganellus in order to understand its resistance to environmental fluctuations (e.g. low tide events, heat waves) and gain insights into its vulnerability to climate change. The upper thermal limit for the species was estimated through the critical thermal maximum (CTMax). Individuals were exposed to a temperature increase ramp of 1°Ch−1. Two thermal stress biomarkers (hsp70 and total ubiquitin) were quantified in the gill, muscle and liver via enzyme linked immunosorbent assays. Results showed no increases in hsp70 in neither of the organs in response to temperature but ubiquitin levels were elevated in liver at 30°C. Both biomarker basal levels were higher in gills, followed by liver and finally muscle. The results indicate that the species, although adapted to the intertidal environment, can experience stress at high temperatures of 30°C and above. Therefore, it may be vulnerable to heat waves, especially occurring during low tides that coincide with the hottest hours of the day during summer, with adverse implications in a climate change scenario that predicts temperature rising and increasing (in length and frequency) periods of extreme heat. The present study also shows that different organs possess distinct heat stress thresholds and responses, hence the importance of multi-organ approaches in order to comprehend the full health status of the organisms following acute thermal challenge.