Dataset: Abalone respiration rates from the Sitka Sound (SSSC)

Methodology: 

Sampling and analytical procedures: 

To determine the effect of current and future seasonal differences in carbonate chemistry on abalone bioenergetics, we exposed juvenile, non-reproductive (36 ± 5 mm) H. kamschatkana to three pH/pCO2 levels (i.e., pHT 8.1, 7.8, 7.5) for four months in a flow-through system at the Sitka Sound Science Center (SSSC) from June-October 2017. We focused on abalone that were close to transitioning to reproductive maturity (~50 mm; Busch et al., 2014 and references therein) so that we could best capture energetic trade-offs during an energetically costly life history period. The four-month long exposure to stable pH conditions was meant to capture seasonal exposures to relatively constant carbonate chemistry conditions during summer and winter that was demonstrated by our environmental monitoring. The pH values were chosen to capture the current seasonal fluctuations in Sitka Sound (7.8-8.2 pHT for winter-summer, respectively) as well as future projections for winter based on RCP 8.5 (i.e., 7.8 – 0.3 = 7.5 pHT; (Mathis et al., 2015)). The temperature and salinity were not manipulated and reflected the seasonal conditions in Sitka Sound from June-October.

At the end of the experiment, we measured the respiration rate and wet weight for the individual abalone. Prior to respirometry measurements, we starved the individuals for two days. We then estimated standard metabolic rate by measuring O2 consumption in a continuously mixed airtight container using fiber optic O2 sensors (Fibox IV, Presens). Respirometry trials were conducted in 130mL glass jars sealed with Plexiglas lids attached with vacuum grease. Each jar was fitted with a self-adhesive oxygen sensor spot (PreSens SP-PSt4-SA), which underwent a daily two-point calibration (air-saturated water for 100% saturation; 0.05% Co(NO3)2 standard solution, 1% Na2SO3 for 0% saturation). Individuals were placed in a jar and submerged in a temperature-controlled water bath. Water inside of the chambers was circulated with a magnetic stirrer, and jars were placed on top of a submersible magnetic stir plate within the water bath. Respirometry trials lasted approximately 15 minutes, and the final mean dissolved oxygen saturation was 85% (+/- 8% SD), suggesting the abalone were not stressed by the oxygen levels experienced during the trials. Oxygen concentration measurements were first converted into moles of oxygen using respirometry vial volume. Then, the rate of oxygen depletion was calculated via linear regression.