Warm microhabitats drive both increased respiration and growth rates of intertidal consumers

摘要

Rocky intertidal organisms are often exposed to broadly fluctuating temperatures as the tides rise and fall. Many mobile consumers living on the shore are immobile during low tide, and can be exposed to high temperatures on calm, warm days. Rising body temperatures can raise metabolic rates, induce stress responses, and potentially affect growth and survival, but the effects may differ among species with different microhabitat preferences. We measured aerial and aquatic respiration rates of 4 species of Lottia limpets from central California, and estimated critical thermal maxima. In a variety of microhabitats in the field, we tracked body temperatures and measured limpet growth rates on experimental plates colonized by natural microalgae. Limpet species found higher on the shore had lower peak respiration rates during high temperature aerial exposure, and had higher critical thermal maxima. Using our long-term records of field body temperatures, we estimated cumulative respiration to be 5 to 14% higher in warm microhabitats. Growth rates in the field appear to be driven by an interaction between available microalgal food resources, low tide temperature, and limpet species identity, with limpets from warmer micro habitats responding positively to higher food availability and higher low tide temperatures. Stressful conditions in warm microhabitats make up a small portion of the total lifetime of these limpets, but the greater proportion of time spent at non-stressful, but warm, body temperatures may result in enhanced growth compared to limpets living in cooler microhabitats.