Presenter/s: Alexa Maine
Symposium Session: 2024 - 11 Restoring Habitat for Overlooked Aquatic Organisms
Topics covered: passive restoration
ABSTRACT
Salmonid-focused restoration can be destructive…to long-lived organisms like freshwater mussels…when they are not properly and carefully planned for.
Freshwater mussels are a First Food for Columbia Basin Tribes like the Confederated Tribes of the Umatilla Indian Reservation (CTUIR), and harvest of mussels remains a reserved treaty right for tribal members. Populations of freshwater mussels are declining rapidly and harvest of mussels is not currently possible. Mussels can form dense beds that provide invaluable ecosystem services on which salmonids and other aquatic life rely. Nutrient cycling, removal of toxins and pollutants, substrate bioturbation, water quality improvement, sediment stabilization, and other services are provided by mussels, but these are seldom considered as benefits to the ecological community when mussels are present in areas in need of habitat restoration.
Salmonid-focused restoration practices can result in long term suitable habitat for mussels. However, in the short term, restoration actions can be destructive and damaging to mussels. Mussels are not often considered in planning phases of restoration projects and, even when planned for, are frequently killed by actions like instream construction, dewatering, sedimentation, channel fill, or wood and boulder placement. Because mussels are long-lived (some species 80-100 years), sessile, and reliant on microhabitat characteristics that are not well understood, relocation of mussels outside of a project area to avoid damage during instream work in many cases results in 50-90% mortality and should be used only a last resort. Alternatives to relocation exist, and resources are available to help habitat restoration professionals avoid moving or damaging mussels during restoration work.
Given the current rate of mussel abundance and richness decline throughout the western US, habitat restoration projects should consider designs that protect and enhance mussels short term and long term. Especially for areas with dense, reproductive beds of mussels, significantly more effort needs to be taken to minimize disturbance and focus project design to restore rivers in a holistic manner. Single species restoration is destructive to often overlooked but highly valuable organisms like mussels, and their benefit to the river ecosystem should be considered in project planning.
Mussels provide significant services to their river community, but they need help from the restoration community to persist and survive. Restoration work is important…so are mussels. Let’s work together to protect, restore, and enhance mussel populations for the good of the entire river community!