Developing environmental flow recommendations for freshwater mussels using the biological traits of species guilds

Abstract

SUMMARY1. North American freshwater mussels (Unionidae) are a diverse and imperilled fauna that are very sensitive to flow alterations. Previous attempts to develop environmental flows for mussels have struggled to accommodate their varied habitat requirements and complex life histories. 2. We review what is known about the habitat requirements of mussels, how they can vary among species within a community, and how this variation influences the effectiveness of different environmental flow methodologies. 3. We propose a trait-based environmental flow method that addresses the needs of mussel guilds differentiated by their thermal tolerances and reproductive strategies. Used previously for fish, plants and macroinvertebrates, the guild approach groups species by traits and identifies flow requirements of guilds as opposed to entire communities. 4. We apply the guild approach to the mussel fauna of the Kiamichi and Little Rivers in southeastern Oklahoma, U.S.A., and illustrate how changes in the hydrograph can be made to better meet the seasonal flow needs of differing mussel guilds and their host fish. 5. The guild environmental flow method can provide flow recommendations that cater to the life history and habitat requirements represented within diverse mussel communities. In addition, the method can be adapted among regions where trait data are available or combined with rating models that estimate trait data for understudied species.

Evaluating the upper thermal limits of glochidia for selected freshwater mussel species (Bivalvia: Unionidae) in central and east Texas, and the implications for their conservation

“…As obligate parasites, freshwater mussels rely on fish hosts to transform into juveniles, and temperature can affect the success of transformation (Roberts & Barnhart, ; Taeubert, El‐Nobi, & Geist, ), the phenological synchrony of glochidial release with host fish occurrence (Pandolfo, Kwak, & Cope, ; Schneider, Nilsson, & Österling, ), and the duration of the parasitic phase (Eybe, Thielen, Bohn, & Sures, ; Taeubert et al, ), which can in turn affect the subsequent survival of the transformed juveniles (Marwaha, Jensen, Jakobsen, & Geist, ). Thus, mussel‐dependent ecosystem services and population resilience are tightly linked to the natural thermal regime (Gates, Vaughn, & Julian, ; Spooner & Vaughn, ), making mussel populations a model system from which to gain a better understanding of how thermal regimes in rivers shape population and community structure for aquatic biota (Allen, Galbraith, Vaughn, & Spooner, ).…”

Freshwater mussels increase survival of largemouth bass (Micropterus salmoides) in drying pools

“…This poses a challenge for water managers as they struggle to meet urban, agricultural, recreational and ecological needs during climate change‐induced water reductions. Maintaining these rivers for the benefit of both recreation and the environmental needs of endangered species is difficult but can greatly improve the conservation outlook for endangered species (Gates et al, ). As recreational fishing contributes to the economy in rural regions (Long & Melstrom, ), conserving sport fish is important.…”

“…Fish survival was not significantly related to glochidial infection (β = −.07, hazard ratio = 0.92, p = .64). Graph made with code from the R package survminer (Kassambara & Kosinski, 2018) needs of endangered species is difficult but can greatly improve the conservation outlook for endangered species (Gates et al, 2015). As recreational fishing contributes to the economy in rural regions (Long & Melstrom, 2016), conserving sport fish is important.…”

“…Heavy glochidial loads can kill infected fish through asphyxia and lesions on the gill tissues (Howerth & Keller, ). For some mussels, the glochidial infection period is highest in summer and overlaps with low‐water conditions (Culp, Haag, Arrington, & Kennedy, ; Gates, Vaughn, & Julian, ); thus, infection may decrease fish survival in drought conditions. While adult mussels compete with fishes for oxygen, they may also subsidise prey for invertivorous fishes by increasing macroinvertebrate abundance (Vaughn et al, ).…”

Implementation of the Natural Flow Paradigm to Protect Dwarf Wedgemussel (Alasmidonta heterodon) in the Upper Delaware River

“…Processes leading to sediment deposition are triggered by discharge modifications, changes of river morphology, for example, flood protection, hydropower use, as well as land use, for example, change of land cover type, and climate change (Leitner et al, 2015). Decreases in river discharge can affect mussel by decreasing water velocity, water depth, increasing sedimentation, changing the thermal regime and water chemistry (Gates et al, 2015). Fine sediments can lodge between coarser grains of the substrate to form a hardpan layer, thereby reducing interstitial flow rates (Boulton et al, 2010;Jones et al, 2015;Scheder et al, 2015).…”