Local-scale thermal history influences metabolic response of marine invertebrates

As climate change continues, anticipating species’ responses to rising temperatures requires an understanding of the drivers of thermal sensitivity, which itself may vary over space and time. We measured metabolic rates of three representative marine invertebrate species (hermit crabs Pagurus hirsutiusculus, periwinkle snails Littorina sitkana, and mussels Mytilus trossulus) and evaluated the relationship between thermal sensitivity (Q10) and thermal history. We tested the hypothesis that thermal history drives thermal sensitivity and quantified how this relationship differs over time (short-term to seasonal time scales) and between species. Organisms were collected from tide pools in Sitka, Alaska where we also recorded temperatures to characterize thermal history prior to metabolic rate assays. Using respirometry, we estimated mass-specific oxygen consumption (MO2) at ambient and increased temperatures for one individual per species per tide pool across three seasons. We evaluated relationships between thermal sensitivity and pool temperatures for time periods ranging from 1 day to 1 month prior to collection. For all species, thermal sensitivity was related to thermal history for the shorter time periods (1 day to 1 week). However, the direction of the relationships and most important thermal parameters (i.e., maximum, mean, or range) differed between species and seasons. We found that on average, P. hirsutiusculus and L. sitkana were more thermally sensitive than M. trossulus. These findings show that variability in thermal history over small spatial scales influences individuals’ metabolic response to warming and may be indicative of these species’ ability to acclimate to future climate change.

Methods
Temperature Data:
Temperature data was collected at the tide pool level using Onset ® HOBO TidbiT temperature loggers (±0.2 accuracy) that recorded temperature consecutively every 5 min from December 2018 to September 2019. Temperature data were summarized for the 1-month, 1-week, and 1-day periods preceding each collection. For each tidepool, we calculated the following thermal parameters: variance, minimum, mean daily minimum, 10th percentile, range, mean daily range, mean daily average, maximum, mean daily maximum, 90th percentile, mean daily 90th percentile, 95th percentile, and mean daily 95th percentile temperatures.

Oxygen Consumption Data:
Raw Oxygen data was collected using Pre-Sens PSt3 sensor spots (PreSens Precision Sensing, Germany) and a 10-channel OXY-10 SMA (G2) oxygen meter (PreSens Precision Sensing, Germany). Data were processed after visual inspection and fit with a linear regression of oxygen consumption over time (only slopes that had an R2>0.90 were used in the analysis).