Juncus bulbosus growth throughout the year and during dissolved gas supersaturation events from hydropower: possible consequences for fish health

Krypsiv på Sorlandet (KPS) 2021-2022

NIVA, NMBU and NORCE collaborated together in 2019, to assess the role of gas supersaturation on aquatic plant photosynthesis and possible effects on fish health (Demars et al 2021). We explained how aquatic plant photosynthesis may contribute to gas supersaturation. We designed a method able to partition the biotic (aquatic plant photosynthesis) from physical supersaturation due to the hydropower plant at Brokke using a noble gas (argon). NIVA installed a monitoring station in Straume for dissolved O2, temperature, and light from 25 November 2019 to 26 November 2020. An additional O2 sensor was also deployed 4 km upstream at Rysstad Øy for the same period (Fig. 1). From these data, we will estimate the growth rate of Juncus bulbosus in Rysstad basin throughout the year using an improved open channel whole stream metabolism method able to cope with rapid changes in hydrology and gas supersaturation events.