Space-time variability in environmental thermal properties and snail thermoregulatory behaviour

Abstract

Summary1. Behavioural adaptations of ectotherms to thermally heterogeneous environments are still overlooked in the literature despite the fact that organismal behaviour could enhance survival in the warming world. This is particularly critical in the intertidal where most ectotherms live at, or near to the upper limit of thermal tolerance. 2. This study investigated (i) the environmental factors determining the body temperatures of the intertidal gastropod Nerita atramentosa, (ii) the space-time variability in environmental and individual body temperatures and (iii) the potential variability in N. atramentosa thermoregulatory behaviours, i.e. microhabitat selection and aggregation. 3. Thermal imaging was used to assess the body temperatures of N. atramentosa and surrounding substrata over two seasons (autumn and summer), at two shore levels (low-vs. high-shore levels) within two habitats of different topographic complexity (rock platform and boulders) on the same rocky shore. 4. Snail body and substratum temperatures were significantly and positively correlated within each habitat at both seasons. Substratum temperature may thus be considered as a primary driver of body temperatures of organisms that attach to a substratum. Substratum temperature and other variables such as solar irradiance critically need to be integrated in climate-change models that use single climatic variables (e.g. air temperature) that are not necessarily correlated with individual body temperatures in nature. 5. The high space-time variability in both substratum and body temperatures reinforces the growing evidence that small spatial scale variations may surpass those observed at larger spatial scales. 6. Nerita atramentosa thermoregulatory behaviour under high thermal stress appeared to be habitat specific. 7. The small spatial scale heterogeneity in environmental and individual temperatures and in thermoregulatory behaviours has stressed the need to focus on body temperature patterns at the niche level and to integrate the organismal behaviour in climate-change models.

Manipulating thermal stress on rocky shores to predict patterns of recruitment of marine invertebrates under a changing climate

“…Emissivity (ε) was set at 0.95 as previous studies demonstrate that ε values of rocky substrata and invertebrates on intertidal shores typically vary between 0.95 and 1 (Denny & Harley 2006, Chapperon & Seuront 2011, Cox & Smith 2011. The ε of polyurethane and polyethylene products (i.e.…”

“…These studies suggested that plates covered with SWT could be a useful way to manipulate temperature at a single intertidal height on rocky shores and to test for effects on early life history processes. Such an experimental manipulation would also benefit from recently developed infrared imaging techniques used to quantify fine-scale variation in both physical and biological characteristics of rocky intertidal shores (Murphy et al 2006, Underwood & Murphy 2008, Chapperon & Seuront 2011, Cox & Smith 2011. The advantage of such infrared sensing is that temperature variability can be assessed at spatial scales relevant to newly settled benthic marine invertebrates.…”

The importance of thermal history: costs and benefits of heat exposure in a tropical, rocky shore oyster

“…Intertidal communities constitute one of the most widely distributed and tractable systems to understand how species can acclimate or adapt to extremely dynamic environments (Helmuth, 1998;Helmuth and Hofmann, 2001;Helmuth et al, 2002Helmuth et al, , 2006Chapperon and Seuront, 2011;Giomi et al, 2014;Fusi et al, 2016). In recent years, the interaction of major environmental drivers, combined with the biotic components of the intertidal habitat, has received great attention as a model system for determining the suite of responses species can exhibit to environmental challenges (Barry et al, 1995;Helmuth, 1998;Helmuth and Hofmann, 2001;Helmuth et al, 2002Helmuth et al, , 2006Harley and Helmuth, 2003;Burrows et al, 2008;Mislan et al, 2009;Chapperon and Seuront, 2011;Sokolova et al, 2012;Mislan et al, 2014).…”

“…In recent years, the interaction of major environmental drivers, combined with the biotic components of the intertidal habitat, has received great attention as a model system for determining the suite of responses species can exhibit to environmental challenges (Barry et al, 1995;Helmuth, 1998;Helmuth and Hofmann, 2001;Helmuth et al, 2002Helmuth et al, , 2006Harley and Helmuth, 2003;Burrows et al, 2008;Mislan et al, 2009;Chapperon and Seuront, 2011;Sokolova et al, 2012;Mislan et al, 2014). In particular, many studies have investigated species' tolerance thresholds to forecast their vulnerability to climate change and to formulate projections that range from individual to community levels (e.g.…”

“…Understanding the thermal responses of ectothermic species is of increasing importance in the light of global warming, especially when considering the effect of climate shifts and instability on the realised thermal niche of species (Etterson and Shaw, 2001;Helmuth et al, 2002;Pörtner, 2002;Pörtner and Knust, 2007;Chown et al, 2010;Bozinovic et al, 2011;Chapperon and Seuront, 2011;Rezende et al, 2011;Anttila et al, 2014;Palumbi et al, 2014;Verberk et al, 2015). The suite of thermal responses utilised by a species, which can entail complex, integrated processes at wholeorganism, cellular and molecular levels, determines their sensitivity to climatic influences and represents the central mechanism for species' thermal adaptation (Pörtner, 2002(Pörtner, , 2010Kassahn et al, 2009;Marshall et al, 2010;Bartolini et al, 2013).…”