Concurrent Sessions A: Passage Effectiveness Monitoring in Small Streams I - Assessing the Effects of Road Crossings on Gene Flow for Fish Populations in Warmwater Streams of the Ouachita National Forest
Location
Construction & Engineering Hall, Oregon State University
Start Date
27-6-2013 10:25 AM
End Date
27-6-2013 10:45 AM
Description
Certain types of road crossings reduce longitudinal movement of stream fishes. We characterized the genetic structure of warm water fish populations as a potential indication of movement barriers in upland streams of the Ouachita National Forest. Fin-clip tissue samples of longear sunfish, Lepomis megalotis and highland stoneroller, Campostoma spadiceum were collected for microsatellite analysis. Initially, we selected two streams with road crossings and two without for reference; however, we added another reference stream because a natural waterfall on one of the reference streams resulted in a measurable barrier-effect. For each stream, a total of 75 to 90 fish of each species representing upstream, downstream, and mid-stream reaches were collected (a total of approximately 800 specimens). DNA was extracted and seven microsatellite primers were selected for highland stonerollers and ten for longear sunfish because the latter showed fewer alleles per loci (Na=11.7 versus 6.2, respectively). We detected an apparent disruption to gene flow in at least three of the five streams (although certain analyses also detected a disruption in a fourth stream and analyses are not yet complete for stonerollers) . Bayesian analysis of the longear sunfish samples predicted a maximum ΔK value at K = 10 indicating 10 distinguishable populations among the 15 sampled sites. This finding was consistent with an FSTAT pair-wise population assignment indicating three longear sunfish populations in Bear Creek, two in Crystal Prong, two in Long Creek, and two in Little Missouri; whereas, Blaylock appeared to have a single population. Populations from all three sites within Bear were distinguishable, including two sites separated by a piped-culvert. A barrier-effect was also detected in Crystal Prong which is a reference stream that has dry reaches, like Bear Creek, in summer. A natural waterfall on the Little Missouri reference stream also appeared as a barrier to gene flow with the two sites upstream of the falls representing a single population that differed significantly from the downstream population. Two populations were detected in Long Creek with the middle reach similar to both the upstream and the downstream, but the upstream differed significantly from the downstream population. Interestingly, the downstream road crossings in Long Creek were box culverts designed to facilitate fish passage; whereas, upstream crossings included the piped-culvert design known to reduce passage of warm water fishes. We detected no barriers to gene flow for Blaylock Creek, a reference stream that flows all summer like Long Creek and Little Missouri. We conclude that improved understanding of genetic structure in warm water fish populations can contribute to our assessment of movement barriers by showing disruption to natural patterns of gene flow in headwater upland streams.
Concurrent Sessions A: Passage Effectiveness Monitoring in Small Streams I - Assessing the Effects of Road Crossings on Gene Flow for Fish Populations in Warmwater Streams of the Ouachita National Forest
Construction & Engineering Hall, Oregon State University
Certain types of road crossings reduce longitudinal movement of stream fishes. We characterized the genetic structure of warm water fish populations as a potential indication of movement barriers in upland streams of the Ouachita National Forest. Fin-clip tissue samples of longear sunfish, Lepomis megalotis and highland stoneroller, Campostoma spadiceum were collected for microsatellite analysis. Initially, we selected two streams with road crossings and two without for reference; however, we added another reference stream because a natural waterfall on one of the reference streams resulted in a measurable barrier-effect. For each stream, a total of 75 to 90 fish of each species representing upstream, downstream, and mid-stream reaches were collected (a total of approximately 800 specimens). DNA was extracted and seven microsatellite primers were selected for highland stonerollers and ten for longear sunfish because the latter showed fewer alleles per loci (Na=11.7 versus 6.2, respectively). We detected an apparent disruption to gene flow in at least three of the five streams (although certain analyses also detected a disruption in a fourth stream and analyses are not yet complete for stonerollers) . Bayesian analysis of the longear sunfish samples predicted a maximum ΔK value at K = 10 indicating 10 distinguishable populations among the 15 sampled sites. This finding was consistent with an FSTAT pair-wise population assignment indicating three longear sunfish populations in Bear Creek, two in Crystal Prong, two in Long Creek, and two in Little Missouri; whereas, Blaylock appeared to have a single population. Populations from all three sites within Bear were distinguishable, including two sites separated by a piped-culvert. A barrier-effect was also detected in Crystal Prong which is a reference stream that has dry reaches, like Bear Creek, in summer. A natural waterfall on the Little Missouri reference stream also appeared as a barrier to gene flow with the two sites upstream of the falls representing a single population that differed significantly from the downstream population. Two populations were detected in Long Creek with the middle reach similar to both the upstream and the downstream, but the upstream differed significantly from the downstream population. Interestingly, the downstream road crossings in Long Creek were box culverts designed to facilitate fish passage; whereas, upstream crossings included the piped-culvert design known to reduce passage of warm water fishes. We detected no barriers to gene flow for Blaylock Creek, a reference stream that flows all summer like Long Creek and Little Missouri. We conclude that improved understanding of genetic structure in warm water fish populations can contribute to our assessment of movement barriers by showing disruption to natural patterns of gene flow in headwater upland streams.
Comments
Charles J. Gagen received his B.S. degree in Wildlife Biology from the University of Tennessee, and M.S. and Ph.D. in Ecology from Penn State University in 1991. Since that time, he has been a professor of fisheries science at Arkansas Tech University, where he currently serves as Head of the Department of Biological Sciences. His research has focused on determining the effects of environmental variables on fish populations and communities especially in upland streams. Early studies documented direct effects of acid rain on cold water fishes; whereas, more recent studies concern responses of warm water fishes to low stream flow. In both cases, movement and mortality have emerged as important aspects of the population dynamics involved. Assessing tendencies of road crossings to adversely affect fish movement fits into a bigger picture of the ecology of stream-dwelling fishes. Dr. Gagen is active in the American Fisheries Society and the Arkansas Chapter, in particular.