Travelling downstream: Thermal challenges facing fish — ASN Events

Travelling downstream: Thermal challenges facing fish (#231)

Valerie Ouellet 1 , M. Daneils 1
  1. Stroud Water Research Center, Avondale, PA, United States
Many studies have shown the stabilizing and reducing effects of riparian buffers on daily maximum temperature and water temperature dynamics (e.g. Studinski et al., 2012; Garner et al., 2013). Few studies have detailed exactly which processes control the cooling and warming of water, the efficiency of the riparian buffer, and how quickly (rate and gradient) the changes happen across landscape segments (Hannah and Garner, 2015). This knowledge is fundamental to understand the quantity of riparian buffer that is needed to achieve thermal restoration and insure the diversity of habitat needed for fish species like brook trout (Salvelinus fontinalis).This study focuses on understanding how riparian landscape changes affect the water temperature and what the downstream cumulative impacts of those variations are. Cooling and warming processes were characterized, as well as the rate of changes between landscapes, over a 6 km stream reach (temperature loggers were deployed each 500 m) where brook trout have been observed. Results show that summer temperatures could be a limiting factor for fish species having a thermal tolerance that does not exceed 24oC. The mosaic of thermal dynamics created by the changes in riparian landscapes also affected the accessibility to thermally appropriate habitat, such as thermal refuge, by limiting the connectivity between suitable habitats. This study informs management recommendations of the riparian zone, especially in connection with brook trout reintroduction.
  1. Garner, G., Hannah, D.M., Sadler, J.P., and Orr, H.G. 2013. River temperature regimes of England and Wales: Spatial patterns, inter-annual variability and climatic sensitivity. Hydrol. Process. 5598(October 2013): 5583–5598. doi: 10.1002/hyp.9992.
  2. Hannah, D. M, Garner G. 2015. In press. River water temperature in the United Kingdom: changes over the 20th century and possible changes over the 21st century. Progress in Physical Geography. DOI: DOI: 10.1177/0309133314550669
  3. Studinski, J.M., Hartman, K.J., Niles, J.M., and Keyser, P. 2012. The effects of riparian forest disturbance on stream temperature, sedimentation, and morphology. Hydrobiologia 686: 107–117. doi: 10.1007/s10750-012-1002-7.
Full Paper