Blood chemistry has proven particularly useful when quantifying the physiological effects of anthropogenic stress on fish (e.g.
Analysing blood chemistry can improve our understanding of animal–environment interactions and provide physiological thresholds that may be critical in overcoming conservation challenges ( Cooke and O'Connor, 2010 Stoot et al., 2014). Point-of-care blood analysers are commonly used as a non-lethal tool to evaluate the health and condition of animals in both veterinary and research settings ( Thrall et al., 2012 Stoot et al., 2014). Additional species should be examined in the future across a wide range of temperatures to determine whether correction factors are universal. Using this device with appropriate correction factors and consideration of calibration temperatures can result in both a rapid and accurate assessment of whole blood pH, at least for the two elasmobranch species examined here. The relative error in the pH meter's measurements was ~☒.7%. There was a significant linear relationship between values derived via the pH meter and the i-STAT for both species across a wide range of pH values and temperatures (Cuban dogfish: 6.8–7.1 pH 24–30☌ lemon sharks: 7.0–7.45 pH 25–31☌).
We compared blood pH values measured using a portable, waterproof pH meter (Hanna Instruments HI 99161) with blood pH values measured by an i-STAT system (CG4+ cartridges), which was previously validated for teleost and elasmobranch fishes, to gauge the accuracy of the pH meter in determining whole blood pH for the Cuban dogfish ( Squalus cubensis) and lemon shark ( Negaprion brevirostris). Current methods for analysing elasmobranch blood chemistry in the field are often costly and logistically challenging.
Quantifying changes in blood chemistry in elasmobranchs can provide insights into the physiological insults caused by anthropogenic stress, and can ultimately inform conservation and management strategies.