MEPS 536:77-88 (2015)  -  DOI: https://doi.org/10.3354/meps11418

ABSTRACT: Accurate predictions of species responses to climate change require a detailed understanding of the temperatures that organisms experience in the wild. We developed biomimetic physical models of 3 common northeastern Pacific intertidal species: 2 predatory dogwhelks, Nucella ostrina and N. lamellosa and their barnacle prey, Balanus glandula. We established 42 biomimetics in up to 11 different microhabitats within an approximately 100 m² region of the shoreline on San Juan Island, Washington, USA. Average temperatures were recorded at 15 min intervals over 3 successive summers. We found large differences in temperatures of N. ostrina biomimetics when placed in different microhabitats; as much as 8°C difference in mean daily maximum temperature and over 30 °C differences on individual days. Solar refuges and differing solar aspects reduced body temperatures, relative to more sun-exposed locations at the same shore height, by as much as moving 0.5 m lower on the shore. When biomimetics of the 3 species were placed in the same habitat, average daily maximum temperatures differed by <0.2°C, a surprisingly small amount. Yet because these species differ greatly in known thermal tolerances, the temperatures imply large differences among species in daily risk of thermal stress (0 to 33.8%). Further, N. ostrina could halve its risk of thermal stress on the high shore by moving between solar aspects. The ability of mobile predators such as Nucella spp. to exploit spatio-temporal variation in temperature likely influences their ability to regulate sessile prey such as B. glandula.

KEY WORDS: Intertidal · Temperature · Nucella · Balanus · Solar aspect · Microhabitat · Foraging