Intraspecific physiological variability of the gastropod Littorina saxatilis related to the vertical shore gradient in the White and North Seas

Physiological adaptations to high intertidal life involve improved water conservation abilities and metabolic rate depression in Littorina saxatilis

“…The tidal range is 1.8-2.2 m at the White Sea sampling site and 1.6-2.8 m at the North Sea location. In general, sub-arctic White Sea populations of Littorina saxatilis experience extreme seasonal variations of temperature, from freezing (from below -1.5°C in brackish seawater to between -10 and -15°C in air) in late autumn and winter to 15-20°C and more in summer (Babkov 1998, Sokolova et al 2000a). In contrast, both temperature fluctuations and temperature extremes are much less pronounced in the North Sea.…”

“…However, temperature and desiccation contrasts between high and low shores are greater for the White Sea population compared with that in the North Sea. During summer low tides, high-shore animals from the White Sea area experience wide temperature fluctuations, temperature extremes of up to 47°C and extreme desiccation stress while spending a long time (up to 7-8 d during neap tides) on dry rock surface (Sokolova et al 2000a). In contrast, Helgoland animals may never be exposed to direct sunlight due to the shore morphology; so the differences in temperature fluctuations and temperature extremes between high-and low-shore habitats are small (Janke 1997, I.M.S.…”

“…Resale or republication not permitted without written consent of the publisher stability of key metabolic enzymes (Hull et al 1999, Sokolova & Pörtner 2001; enhanced expression of heatshock proteins (Sanders et al 1991, Tomanek & Somero 1999, 2000; and morphological, behavioural and physiological adaptations ensuring increased extracorporal water storage, reduced evaporation and/or increased irradiative heat loss (Cleland & McMahon 1986, McQuaid & Scherman 1988, Britton & McMahon 1990, McMahon 1990, Britton 1995, Sokolova et al 2000a). …”

“…The intertidal gastropod Littorina saxatilis has a wide vertical distribution occurring from the upper subtidal to the supratidal splash zone and thus encounters environments with greatly differing temperature and humidity regimes within the range of a single population (Sokolova et al 2000a). This pattern allows us to compare animals adapted to life at different shore levels within ecologically, morphologically and genetically cohesive units such as a single species (or even a single population) and thus to avoid problems immanent to the interspecific comparison of environmental adaptation (Garland & Adolf 1994).…”

“…At high-shore levels, the environmental conditions may not only become more extreme but are also characterised by high temporal instability and unpredictability. Numerous studies have shown that adaptation to life in the high intertidal may involve the increased thermal resistance of an organism (Stirling 1982, McMahon 1990, Sokolova et al 2000a); heat ABSTRACT: Mortality, rates of water loss, aerobic and anaerobic metabolic rates and changes in the parameters of cellular energy status were monitored in the intertidal gastropod Littorina saxatilis from different latitudes and shore levels during prolonged air exposure at elevated temperatures (30°C). Prolonged air exposure, imitating environmental conditions during summer low tide at highshore levels, resulted in the onset of anaerobic metabolism, as indicated by the significant accumulation of succinate and alanine and a considerable depletion of high-energy phosphates (ATP and phospho-L-arginine, PLA).…”