Influence of Forest Road Culverts and Waterfalls on the Fine‐Scale Distribution of Brook Trout Genetic Diversity in a Boreal Watershed

Abstract

Habitat fragmentation has become an increasing concern in conservation biology and is of prime importance with the expansion of forest road networks toward boreal and arctic regions. The aim of this study was to evaluate the effects of artificial and natural barriers to fish movement on the fine‐scale distribution of genetic diversity in Brook Trout Salvelinus fontinalis. We genotyped 995 individuals sampled from 25 locations in a boreal watershed fragmented by culverts and natural waterfalls. Using a landscape genetics approach, we tested whether the presence of both types of barrier resulted in decreased genetic diversity and increased divergence within isolated locations. Results showed that genetic divergence was enhanced between sites separated by barriers and that genetic diversity was reduced within sites located upstream of barriers. Moreover, the observed changes in levels of divergence and diversity were correlated with the number of barriers. Overall, our results suggested that the effects of culverts and natural waterfalls were similar. To our knowledge, this is the first study illustrating the effects of forest road culverts and natural waterfalls on the distribution of genetic diversity in Brook Trout within a boreal watershed. We discuss our results in the context of boreal forest road network expansion and in light of the need to better understand the potential impacts of road infrastructure on the long‐term persistence of fish populations. Received January 24, 2014; accepted July 11, 2014

Genetic diversity, admixture, and hatchery influence in Brook Trout (Salvelinus fontinalis) throughout western New York State

“…Nathan et al () found that in Connecticut, Brook Trout populations located upstream of road culverts displayed lower diversity values ( A R : 2.74–4.85, H e : 0.464–0.775, based on 17 populations) than populations unaffected by culverts ( A R : 3.10–4.62, H e : 0.625–0.761, based on 11 populations). Torterotot et al () also described reduced genetic diversity in Brook Trout populations located upstream of barriers. In general, our study found that Brook Trout populations with a high degree of connectivity and wild–wild admixture tended to also exhibit higher levels of genetic variation than populations where little to no admixture was detected.…”

“…With the increased fragmentation of Brook Trout populations due to habitat alterations (Timm et al, ; Torterotot et al, ; Whiteley et al, ), extirpation of nearby populations (Letcher et al, ), and thermal barriers associated with increased temperatures (Aunins et al, ), population monitoring is essential to minimize the rate of species decline. Incorporating genetic tools into population assessments can reveal previously unrecognized barriers to dispersal and identify population‐level relationships that can help inform management delineations and translocation decisions.…”

“…Populations can be isolated by factors other than distance, and barriers to fish passage play a large role in population fragmentation (Nathan, Kanno, & Vokoun, ; Timm et al, ; Torterotot et al, ). This is evident in population ANR, Newton Run, which exhibited low levels of diversity and was also represented in the box plots as an outlier or at the extreme low end of the range (Figure A2 in Appendix ).…”

A portrait of a sucker using landscape genetics: how colonization and life history undermine the idealized dendritic metapopulation

“…), brook trout (Torterotot et al . ), three‐spined stickleback ( Gasterosteus aculeatus L.) (Raeymaekers et al . ) and Cottus gobio (Hänfling & Weetman ).…”

Road culvert restoration expands the habitat connectivity and production area of juvenile Atlantic salmon in a large subarctic river system

“…; Torterotot et al . ). In line with this, a review of effectiveness of habitat rehabilitation techniques ranked the connection of isolated habitats by improving passage among the most successful ones (Roni et al .…”