Forsøksdyr: Faecal Production Rate - coastal fish

Godkjenningsdato 10.02.2020

Godkjenningsperiode 11.02.2020-10.02.2021

The behaviour and life processes of fish have a role in the biological carbon pump, a key process that contributes to the ocean´s function as a carbon sink and reservoir of carbon dioxide, a greenhouse gas. Many fish populations are managed to achieve sustainability and conserve biodiversity, thus there may be opportunities to secure climate change mitigation benefits through existing management approaches. However, data to quantify carbon flux associated with fish is scarce. As part of a research project to explore this opportunity, this experiment will begin to address this lack of data for temperate coastal ecosystems, by quantifying the rate of faecal pellet and metabolised carbonate production for a range of coastal fish species found throughout the Skagerrak coast.

We plan to extend on a previous experiment (Faecal Production Rate - coastal predator, FOTS application no. 19300) by examining two species, Atlantic cod and goldsinny wrasse, for up to 39 days of feeding at different water temperatures.

Stress to the animals will be minimal: we plan to hold the fish, feed them food that reflects their natural diet, take a small clip from their tail fin, and release them back to their natural habitat. To minimize the stress during handling and data collection, fish are immediately placed into water and carried to tanks. Fish are held for the minimum possible time and disturbed only to measure and remove faecal material from the tank using a small hose with suction or a pipette. To minimise stress, the tanks have a large dark plastic sheet with fronds cut in which floats at the surface to act as artificial kelp, giving the fish somewhere to hide. The tanks also have nets placed over the top that prevent animals from jumping out. If a fish becomes ill, sustains an injury or appears to have deteriorated to a point from which it is unlikely to recover, it will be euthanised. For goldsinny wrasse, water temperature will be increased by 1 degree per day to a maximum of 5 degrees above control temperature, then later decreased by 1 degree per day back to the control temperature.

Coastal fish are chosen for this experiment to provide an overview of the conversion of food to faeces by fish in a temperate coastal ecosystem, as a proxy for other temperate coastal ecosystems in the North Atlantic. We can combine the experimental data with existing field data collected on local coastal fish abundance along the Skagerrak coast. By combining this existing data with the results from the lab experiment, we will gain valuable insight and can begin to quantify the role of temperate coastal ecosystems and fish in carbon cycling.