Successful establishment of endangered springsnails following habitat enhancement and translocations

Abstract

1. Spring-associated aquatic invertebrates tend to be narrow-range endemics.Globally, they are threatened with extinction as a result of habitat loss caused by declining aquifers and by climate change.2. Extinction risks to narrow-range endemics may be reduced by having multiple, separate populations, yet there have been few attempts to use conservation translocations to create new populations.3. Pyrgulopsis roswellensis (Roswell springsnail), Juturnia kosteri (Koster's springsnail) and Gammarus desperatus (Noel's amphipod) are range-restricted, springassociated endangered species. Each species has lost one or more populations owing to habitat loss, and their distributions are now largely restricted to Bitter Lake National Wildlife Refuge, New Mexico. 4. In 2014, Bitter Lake National Wildlife Refuge enhanced a series of springs by rerouting a channelized section of river away from them. The goal was to create habitat suitable for establishing new populations of P. roswellensis and J. kosteri, and for expansion of G. desperatus. After assessing risks and benefits of translocations, approximately 6,177 P. roswellensis and 8,707 J. kosteri were introduced into the project area from 2015 to 2018. 5. Efficacy was evaluated by comparing the abundance of invertebrates in the translocation site through time, and by comparing springsnail abundance with three reference spring systems. From 2014 to 2021, invertebrates were monitored twice annually in the translocation area. In reference spring systems, P. roswellensis and J. kosteri were monitored twice annually in 2020 and 2021.6. Counts of springsnails in the translocation area were comparable to one or more reference areas, which suggests that translocations were successful. In addition, the proportion of P. roswellensis, the less common springsnail, to J. kosteri was similar to references areas. 7. G. desperatus did not increase, which may be because some measures of water quality have not stabilized. 8. Globally, climate change and aquifer declines necessitate immediate consideration be given to conservation translocations as a means of keeping spring-associated species from becoming extinct.

Translocation in a fragmented river provides demographic benefits for imperiled fishes

“…Translocation above barriers can aid conservation by augmenting populations and mitigating the effects of habitat fragmentation and loss within a species' native range. Translocations might be useful where managers desire to accomplish multiple objectives, such as providing access to important habitats upstream of barriers for native species while precluding dispersal by invasive species (e.g., Rahel & McLaughlin, 2018), creating population redundancy for imperiled species (Healy et al, 2020; Johnson et al, 2022), expanding or augmenting a species' distribution in fragmented ecosystems (Harig & Fausch, 2002; Nissen et al, 2023; White et al, 2003), or aiding in the recovery of species in rapid decline (Hammond et al, 2022; Sheller et al, 2006). Studies of conservation translocations have focused on birds and mammals, with fewer studies on fishes (reviewed by Bubac et al, 2019), and defining success can be difficult if objectives are not explicitly stated a priori (Bubac et al, 2019; Ewen et al, 2014; Minckley, 1995).…”