Acute effects of gas supersaturation on Atlantic salmon smolt in two Norwegian rivers
- PDF / 6,469,524 Bytes
- 12 Pages / 547.087 x 737.008 pts Page_size
- 38 Downloads / 148 Views
(0123456789().,-volV) (0123456789().,-volV)
PERSPECTIVES ON SUSTAINABLE HYDRO-POWER
Acute effects of gas supersaturation on Atlantic salmon smolt in two Norwegian rivers Sondre Kvalsvik Stenberg
. Gaute Velle . Ulrich Pulg . Helge Skoglund
Received: 27 February 2020 / Revised: 17 September 2020 / Accepted: 12 October 2020 Ó The Author(s) 2020
Abstract Total dissolved gas (TDG) supersaturation downstream of hydropower plants may cause gas bubble disease (GBD) and harmful effects in fish. Little is known about tolerance levels of TDG supersaturation on Atlantic salmon (Salmo salar Linnaeus, 1758) in natural rivers. The present study investigated the effects of TDG supersaturation on the survival of Atlantic salmon smolts at two field sites in Norway. Here, we kept smolts in cages at increasing distances from hydropower plants known to cause TDG supersaturation and at control sites. We recorded fish mortality and examined for GBD using a stereo microscope. Mortality and symptoms of GBD commenced in fish exposed to an average of 108.3% TDG (maximum 111.0%, water depth 0.55 m) for 2 days. Significant differences in time before mortality at the
Guest editors: Ingeborg P. Helland, Michael Power, Eduardo G. Martins & Knut Alfredsen / Perspectives on the environmental implications of sustainable hydropower S. K. Stenberg (&) Norwegian Institute for Water Research, Gaustadalle´en 21, 0349 Oslo, Norway e-mail: [email protected] G. Velle U. Pulg H. Skoglund Norwegian Research Centre, Nyga˚rdsgaten 112, 5008 Bergen, Norway G. Velle Department of Biological Sciences, University of Bergen, Thormøhlensgate 53 A & B, 5006 Bergen, Norway
control sites and test sites commenced at 110.2% TDG (maximum 111.8%) for 3 days. The study indicates that Atlantic salmon may be more vulnerable to TDG supersaturation than Pacific salmonids, which are considered at risk when the TDG is above 110%. In addition, the study provides important data to link effects caused by TDG in the laboratory and in the field. Keywords Hydropower Total dissolved gas Gas bubble disease Bleke Salmo salar Supersaturation
Introduction Both water pressure and temperature are often affected by river regulation and both these factors affect total dissolved gas (TDG). Gas supersaturation of water occurs when TDG pressure exceeds total atmospheric pressure at the water surface (i.e., total dissolved gas saturation[100%; Weitkamp, 2000). With increasing temperature, gas solubility decreases and TDG increases by approximately 2% per 1°C in water (Marking, 1987). TDG is also affected by water pressure due to the increasing amount of gas that can be dissolved in water with increasing pressure and thus increasing depth (about 10% per m of water depth), according to Henry’s law (Henry, 1803). Gas supersaturation can occur naturally in rivers, for example
123
Hydrobiologia
during rapid solar heating, algal blooms and downstream from waterfalls plunging into deep pools (Marking, 1987). It can also arise from human activity in at least two situations:
Data Loading...
