High value of ecological information for river connectivity restoration

Abstract

Context Efficient restoration of longitudinal river connectivity relies on barrier mitigation prioritization tools that incorporate stream network spatial structure to maximize ecological benefits given limited resources. Typically, ecological benefits of barrier mitigation are 5 measured using proxies such as the amount of accessible riverine habitat.Objectives We developed an optimization approach for barrier mitigation planning which directly incorporates the ecology of managed taxa, and applied it to an urbanizing salmonbearing watershed in Alaska.Methods A novel river connectivity metric that exploits information on the distribution and 10 movement of managed taxon was embedded into a barrier prioritization framework to identify optimal mitigation actions given limited restoration budgets. The value of ecological information on managed taxa was estimated by comparing costs to achieve restoration targets across alternative barrier prioritization approaches.Results Barrier mitigation solutions informed by life history information outperformed those 15 using only river connectivity proxies, demonstrating high value of ecological information for watershed restoration. In our study area, information on salmon ecology was typically valued at 0.8-1.2M USD in costs savings to achieve a given benefit level relative to solutions derived only from stream network information, equating to 16-28% of the restoration budget.Conclusions Investing in ecological studies may achieve win-win outcomes of improved 20 understanding of aquatic ecology and greater watershed restoration efficiency.

Prioritizing conservation actions in urbanizing landscapes

“…Nevertheless, migratory species, such as salmonids, do use a mosaic of interconnected watersheds at different points in their life history. Thus, there may be less benefit to some species if restoration and preservation strategies produce a scattershot suite of locally “cost efficient” restoration sites than if the broader landscape of functionally connected habitat corridors are incorporated into planning 63 . For coho, this might involve, for example, incorporating knowledge of source and sink populations 45 .…”

“…For coho, this might involve, for example, incorporating knowledge of source and sink populations 45 . Our prioritization framework and analysis could be modified to include connectivity across watersheds, using standard approaches to penalize sites based on fragmentation 64 , 65 and promote sites known to be ecologically significant to target species 63 .…”

Connectivity between lentic and lotic freshwater habitats identified as a conservation priority for coho salmon

“…Fish and Wildlife Service, 2019); however, this represents an important policy opportunity in future in many other systems throughout the Pacific salmon range (Silva et al, 2018). Furthermore, retrofitting existing water conveyance projects can be expensive, but recent advancements in optimal fish passage restoration now provide tools for catchment managers to directly incorporate life history of target taxa into restoration decisions and maximize ecological benefits of fish passage barrier mitigation within limited budgets (O'Hanley et al, 2013; Sethi et al, 2017).…”

A Gateway to Successful River Restorations: A Pre-Assessment Framework on the River Ecosystem in Northeast China

“…Restoration practitioners have more experience in judging the technical feasibility, ecological applicability, and social-economic availability of preliminary measures [36]. The river restoration projects are often small-scale given relatively limited budget from the local government, especially in developing regions [28,37,38].…”