The Effects of Thermal Stress on Balanus glandula

Global climate change has become an increasing source of concern due to the recent build-up of greenhouses gases in the atmosphere. The rocky intertidal zone, as the interface between land and sea, is particularly vulnerable to climate change. Many inhabitants of the intertidal zone are sessile and thus experience both terrestrial and aquatic lifestyles at low and high tides, respectively. When emersed at low tide, organisms experience a number of abiotic stresses including heat stress, desiccation stress, and low oxygen availability. Most intertidal organisms have evolved from marine animals and respire most efficiently in water. Barnacles are one such type of intertidal organism. At low tide barnacles face a tradeoff between access to oxygen and loss of water through evaporation. In this study, individuals of the species Balanus glandula, a common intertidal barnacle, were exposed to temperatures of 16°C, 24°C, 30°C, and 35°C for four hours in simulated low tide to determine when aerial respiration occurred. Oxygen levels were measured over the four hours of the exposure and oxygen consumption rates were calculated. Oxygen consumption occurred at all temperatures studied, but the rates at different temperatures were not significantly different from each other. The results showed that barnacles can conduct aerial respiration over the entire course of the low tide exposure despite the risk of desiccation. This indicates that ATP demand remains substantial throughout the low tide and that resorting to anaerobic respiration is not sufficient to meet metabolic needs during low tide exposure