Validation of a portable, waterproof blood pH analyser for elasmobranchs.

Oliver Shipley,John W Mandelman,Brendan Talwar,Jodie L Rummer,R Dean Grubbs,Edward J Brooks,Ian A Bouyoucos

doi:10.1093/conphys/cox012

Abstract

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. Current methods for analysing elasmobranch blood chemistry in the field are often costly and logistically challenging. 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). 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°C; lemon sharks: 7.0-7.45 pH 25-31°C). The relative error in the pH meter's measurements was ~±2.7%. 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. Additional species should be examined in the future across a wide range of temperatures to determine whether correction factors are universal.

Highlights

Point-of-care blood analysers are commonly used as a nonlethal tool to evaluate the health and condition of animals in both veterinary and research settings (Thrall et al, 2012; Stoot et al, 2014)
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)
We established significant linear relationships between the values derived via the pH meter and the i-STAT device for both Cuban dogfish and lemon shark whole blood across a range of pH values and, for the lemon shark, over two seasonal temperature ranges

Summary

Introduction

Point-of-care blood analysers are commonly used as a nonlethal tool to evaluate the health and condition of animals in both veterinary and research settings (Thrall et al, 2012; Stoot et al, 2014). Cooke et al, 2005; Arlinghaus et al, 2009; Foss et al, 2012), including the effects of commercial (Hyatt et al, 2012), recreational Fisheries capture induces a physiological stress response in sharks (and teleost fishes) that is characterized by varying degrees of metabolic and/or respiratory acidoses, the total magnitude of which can be quantified by measuring blood pH (Cliff and Thurman, 1984; Hoffmayer and Parsons, 2001; Mandelman and Skomal, 2009; Brooks et al, 2012). Depressed blood pH can be correlated with mortality (Cliff and Thurman, 1984; Skomal, 2006; Skomal and Mandelman, 2012), making it a valuable and commonly used metric to assess stress in field studies on elasmobranchs (e.g. Mandelman and Skomal, 2009; Brooks et al, 2012; Frick et al, 2012; Hyatt et al, 2012)

Methods

Results

Conclusion