Double whammy

Subtitle:nitrate pollution heightens susceptibility to both hypoxia and heat in a freshwater salmonid

Species persistence in a changing world will depend on how they cope with co-occurring stressors. Stressors can interact in unanticipated ways, where exposure to one stressor may heighten or reduce resilience to another stressor. We examined how a leading threat to aquatic species, nitrate pollution, affects susceptibility to hypoxia and heat stress in a salmonid, the European grayling (Thymallus thymallus). Fish were exposed to nitrate pollution (0, 50 or 200 mg NO3- L-1) at two acclimation temperatures (18 degrees C or 22 degrees C) for eight weeks. Hypoxia- and heat-tolerance were subsequently assessed, and the gills of a subset of fish were sampled for histological analyses. Nitrate-exposed fish were significantly more susceptible to acute hypoxia at both acclimation temperatures. Similarly, in 18 degrees C- acclimated fish, exposure to 200 mg NO3- L- 1 caused a 1 degrees C decrease in heat tolerance (critical thermal maxima, CTMax). However, the opposite effect was observed in 22 degrees C-acclimated fish, where nitrate exposure increased heat tolerance by similar to 1 degrees C. Further, nitrate exposure induced some histopathological changes to the gills, which limit oxygen uptake. Our findings show that nitrate pollution can heighten the susceptibility of fish to additional threats in their habitat, but interactions are temperature dependent. (C) 2020 Elsevier B.V. All rights reserved.

Publication year:2021

Keywords:A1 Journal article

BOF-keylabel:yes

BOF-publication weight:6

CSS-citation score:2

Authors:International

Authors from:Higher Education

Accessibility:Closed