Field Respirometry: Measuring the Natural Metabolic Rate of Invasive Round Gobies During a Heatwave
Background
Fieldwork often comes with surprises, and sometimes with unexpected technical challenges. During a recent field campaign on the Saône river in France, our team was measuring the oxygen consumption of invasive round gobies (Neogobius melanostomus) directly under natural conditions during a summer heatwave (18 to 26°C in less than 10 days). Our field session was supported by the Biodiversaone project (Agence de l’Eau RMC) and by the Carapate project (CNRS-EDF-INRAE).
Set-Up/Sample
The objective of this experiment was to estimate the field metabolic rate of round gobies over a 24-hour period under natural conditions, using a Canadian field respirometry system developed in collaboration with David Deslauriers and Frédéric Bélanger (ISMER-Université du Québec à Rimouski, Canada) and equipped with PyroScience oxygen probes. This approach allowed us to record directly fish respiration under the realistic environmental conditions of the field, rather than only in controlled laboratory settings.
Photo 1 – Field respirometry setup: Field respirometry system deployed to measure 24-hour oxygen consumption of invasive round gobies under natural river conditions, the Saône River (France)
Photo 2 – A round goby in the respirometer: Gobies stayed over 24 hours in the respirometric chamber to measure their metabolic rate
To improve the accuracy of these measurements, we also deployed an additional residual oxygen correction system developed at LEHNA, Université Lyon 1, during the postdoctoral work of Léopold Ghinter, in collaboration with Loïc Teulier and Ludovic Guillard. This setup used a PyroScience optical oxygen sensor to quantify residual oxygen dynamics in an empty chamber, to better correct fish metabolic rate estimates for background oxygen consumption or production.
Photo 3 — Residual oxygen correction system: PyroScience oxygen optodes were used to monitor residual oxygen dynamics in empty chambers and improve metabolic rate corrections
Photo 4 — Fieldwork team: International collaboration in action: Canadian field respirometry expertise combined with LEHNA physiological ecology approaches at Université Lyon 1
Results
In total, we successfully measured 18 individual gobies, each over a full 24-hour period in natural field conditions. These data will help us better understand how invasive fish species cope with environmental stress, especially during extreme events such as heatwaves.
Conclusion
The campaign could have been seriously compromised when one oxygen optode cable was accidentally damaged in the field. Thanks to the exceptional responsiveness of PyroScience, a new optode was sent to replace the former and delivered in less than 24 hours. This rapid support allowed us to continue the experiment almost immediately and to complete the residual oxygen correction measurements as planned.
We are very grateful towards PyroScience and Bionef, their distributor in France, for their technical support, their reactivity, and for helping us adapt quickly to the unpredictable nature of fieldwork. Their support directly contributed to the success of this international collaboration between Canadian researchers and the LEHNA team at Université Lyon 1.
Loïc Teulier, Léopold Ghinter, Ludovic Guillard
Laboratoire d’Ecologie des Hydrosystèmes Naturels et Anthropisés, LEHNA, Université Lyon 1
In collaboration with David Deslauriers and Frédéric Bélanger
ISMER-Université du Québec à Rimouski