Abstract:
Intertidal organisms at high latitudes experience multiple stresses created by freezing, including ischemia, free water reduction, and distortion and destruction of cells, and in response have adapted behavioral and physiological solutions. This study examined the response of intertidal organisms in Kachemak Bay, Alaska to freezing through laboratory experiments and field studies. Mytilus trossulus, Balanus glandula, Protothaca staminea and various limpets (Lottidae) survived freezing conditions to -10 and -20°C, depending on the season. Mytilus trossulus and B. glandula survived multiple freeze events at -10°C. Seasonal freeze response was not induced by exposure to low air temperature in M trossulus. Exposure to O⁰C was not fatal to any of the species studied: M trossulus, B. glandula, P. staminea, limpets, Fusitriton oregonensis, Katharina tunicata and Leptasterias hexactis. Preliminary results suggest that M trossulus and P. staminea have an ice nucleator. Freezing avoidance may be one cause for the differences seen in seasonal distribution patterns of F. oregonensis, Nucella lima, Onchidella borealis, Siphonaria thersites and Littorina sitkana. The current study demonstrated that intertidal organisms in this region exhibit differing responses to freezing. Some organisms survive freezing conditions by freeze tolerance, while others may avoid it by moving lower in the intertidal.
