TY - JOUR
T1 - Catchment-scale effects of river fragmentation: A case study on restoring connectivity
AU - Birnie-Gauvin, Kim
AU - Nielsen, Jan
AU - Frandsen, Sten Bøgild
AU - Olsen, Hans-Martin
AU - Aarestrup, Kim
PY - 2020
Y1 - 2020
N2 - More than two thirds of large rivers worldwide are fragmented, threatening freshwater biodiversity, river integrity, and the services that freshwater ecosystems provide for human populations around the globe. In an effort to alleviate the impacts of barriers, engineered solutions have been developed, though with somewhat underwhelming results. River restoration, especially dam removal, is viewed as the optimal option though seldom the go-to approach. In this study, we evaluated the effects of a large restoration project (pseudo dam removal) in River Kolding, Southern Jutland, Denmark, via a before-after-control-impact (BACI) approach. Using a large dataset of electrofishing data from 74 sites (including downstream unaffected sites, reconnected sites and upstream regulated sites), we found that habitat connectivity was restored successfully, with a large increase in young-of-the-year brown trout (Salmo trutta) at reconnected sites, reaching similar densities to downstream (non-affected) sites. We further observed a decrease in length at reconnected sites, suggesting that natural spawning and rearing habitats were successfully restored too.
AB - More than two thirds of large rivers worldwide are fragmented, threatening freshwater biodiversity, river integrity, and the services that freshwater ecosystems provide for human populations around the globe. In an effort to alleviate the impacts of barriers, engineered solutions have been developed, though with somewhat underwhelming results. River restoration, especially dam removal, is viewed as the optimal option though seldom the go-to approach. In this study, we evaluated the effects of a large restoration project (pseudo dam removal) in River Kolding, Southern Jutland, Denmark, via a before-after-control-impact (BACI) approach. Using a large dataset of electrofishing data from 74 sites (including downstream unaffected sites, reconnected sites and upstream regulated sites), we found that habitat connectivity was restored successfully, with a large increase in young-of-the-year brown trout (Salmo trutta) at reconnected sites, reaching similar densities to downstream (non-affected) sites. We further observed a decrease in length at reconnected sites, suggesting that natural spawning and rearing habitats were successfully restored too.
KW - Fish passage
KW - Fragmentation
KW - Hydropower
KW - Migration
KW - Restoration
KW - Salmo trutta
U2 - 10.1016/j.jenvman.2020.110408
DO - 10.1016/j.jenvman.2020.110408
M3 - Journal article
C2 - 32217310
SN - 0301-4797
VL - 264
JO - Journal of Environmental Management
JF - Journal of Environmental Management
M1 - 110408
ER -