PHYSIOLOGICAL ECOLOGY AND INTERTIDAL ZONATION IN LIMPETS (ACMAEA): A CRITICAL LOOK AT "LIMITING FACTORS"

Abstract

The striking intertidal gradient from marine to terrestrial physical conditions is correlated with an equally obvious spatial partitioning of the habitat by groups of animals. This has repeatedly given rise to the assumption that terrestrial physical factors, acting during tidal emersion, determine the upper range limits of intertidal populations. This assumption is elevated to the level of a hypothesis in this study and tested with scientific rigor. If conditions in the physical environment serve as "limiting factors," determining the partitioning of the intertidal, it should be demonstrable that (a) interspecific differences in physiological tolerances exist and permit differential exploitation of the habitat, and (b) conditions in the microenvironment of the animals exceed the physiological tolerances at the fringes of ranges and, by causing mortality, prevent range extension.

The role of stochastic thermal environments in modulating the thermal physiology of an intertidal limpet, Lottia digitalis

“…repetitive nature of heat stress over low tide periods, unpredictable or stochastic magnitudes of temperature change) are important in structuring the thermal physiology of intertidal organisms (Denny et al, 2011;Montalto et al, 2016). Intertidal organisms can better tolerate heat stress during emersed conditions (low tide) compared with submersed conditions (high tide) (Wolcott, 1973;Jones et al, 2009;Bjelde and Todgham, 2013;Huang et al, 2015). These studies provide evidence that intertidal species may have the capacity to maintain or recruit physiological mechanisms when aerially emersed that better equip them to tolerate heat stress.…”

“…Lottia digitalis, the fingered limpet, is a rocky intertidal species that is found in the middle to upper intertidal zone and is routinely exposed to large fluctuations in environmental variables during low tide periods (Wolcott, 1973). Specifically, we examined how repeated heat stress of constant and predictable magnitude versus that which is stochastic or unpredictable in nature modulated the temperature sensitivity and upper temperature tolerance of limpets to an extreme heat wave.…”

Evaluation of effective shore level as a method of characterizing intertidal wave exposure regimes

“…Zonation is thought to reflect changes in patterns of emersion and immersion with vertical position on the shore. The timing and duration of emersion modulate the degrees of desiccation, temperature, and salinity stress an organism experiences (Wolcott 1973, Stillman and Somero 1996, Wethey 2002, Dahlhoff 2004; conversely, the duration of immersion regulates feeding time, photosynthesis, and in some cases susceptibility to predation (Connell 1961, Paine 1966, Bell 1993). Thus zonation is thought to reflect species-specific physiological and ecological tolerance of immersion and emersion patterns.…”

Mollusks: how are they arranged in the rocky intertidal zone?

“…This study indicated that different species have different distribution patterns throughout the intertidal zone, depending on the biological aspects of each species. The possible limiting factors are resistance to desiccation and high temperatures during the low-tide periods (Wolcott, 1973).…”

“…Past research has shown that organisms living in the upper zones of a rocky shore have higher lethal temperatures, increased tolerance to dehydration, and greater resistance to osmotic stress (Wolcott, 1973). The gastropod N. virginea is common in estuaries, and is resistant to wide variations in salinity (Barroso & Matthews-Cascon, 2009).…”