Climate change is predicted to increase the future thermal conditions in northern latitudes with the potential effect of altering the metabolic scope and potential fitness of aquatic ectotherms. We experimentally tested the effect of elevated egg incubation temperature on the metabolic scope in juvenile brown trout (Salmo trutta). Brown trout cohorts from anadromous and resident crosses were raised from egg through exogenous feeding of juveniles in either natural river temperatures (cold) or elevated (+ 3 °C, warm) temperatures. In respirometry studies, we measured oxygen consumption rates of juvenile trout from both incubation temperatures and all possible breeding crosses after they were feeding exogenously and at an ambient temperature of 13 °C. These measures were taken over a period where the trout were resting, allowing for the determination of standard metabolic rate (SMR), and followed by a chase to exhaustion allowing for the measure of the maximum metabolic rate (MMR).  The aerobic scope (AS) of these juveniles from four anadromous-resident crosses and from both incubation temperatures could then be calculated as AS = MMR – SMR. This dataset represents a key to all respiration trials including: fish embryonic incubation temperature, parental cross, fish total length (mm), calculated mass (g) per fish, ventilation rate (opercular beats/min), and water temperature per respiration trial. For each fish tested, the dissolved oxygen levels in the respirometry chamber were recorded continuously through periods of static respiration and recharge flow in 15 sec intervals for the duration of the trial testing periods (~ 5-7 hrs).  These data were evaluated for SMR and MMR using a respiration program (respR) in the R statistical program.

Respiration (oxygen consumption) and ventilation rates were measured on juvenile trout from two incubation temperature and four parental crosses from June 1 to 4 June, 2018. Two static flow respirometry systems, each with four fiber-optic dissolved oxygen sensors per system (two 4-channel FireStingO₂ Optical Oxygen Meters, PyroScience™, Aachen, Germany) measured dissolved oxygen in 50 ml respirometry chambers individually housing trout. An external digital thermocouple (Pt100-TSUB21 Temperature Probe, PyroScience™, Aachen, Germany) from each system enabled automatic temperature compensation of the oxygen sensor signals by the FireStingO₂ software. A single 500 L fiberglass tank (water depth 30 cm), continuously supplied both submerged systems with fresh river water. With two systems of four optical sensors each, all eight parental cross and incubation temperature could be measured simultaneously. Measurement intervals were 15 s per reading with 15 min under static flow (i.e. no flow), and 15 min as a water recharge period over a 5-7 hr trial. The 50 ml size of each chambers did not facilitate mixing devices, but opercular ventilation and fish movements contributed to mixing in the chambers. Baseline measures of dissolved oxygen were taken at the initial and conclusion of the trials. During the last static respiration measurement period, a video recording was made of each fish so their ventilation rates in opercular beats per min could be determined. At the conclusion of measurements on resting trout, each fish was chased to exhaustion (2 min) in a circular chase chamber and quickly (< 10 sec) returned to the respirometry chamber for measures of maximum oxygen consumption. All fish were only tested once, and if trials had oxygen levels < 80% of recharge levels after three measurement periods these fish were omitted (n = 8).  In this dataset, those trials include trout #: 2, 30, 51, 54, 55, 67, 78, and 79. While 12 replicate trials were started, 11 were used because of a computer malfunction at the initiation of data recording in trial 4.

This is an Excel file with the initial tab including a key and summary data on the fish and respirometer conditions for each trial. The remaining 88 worksheet tabs contain the dissolved oxygen measures for each individual fish tested. Each measure represents an interval of 15 sec. The data (8 fish: #2, 30, 51, 54, 55, 67, 78, and 79) that did not meet the criteria of oxygen levels falling below 80% of the recharge oxygen level past the first three measures are marked on their data worksheets.