Rudolfsen, T.*, Watkinson, D. and Poesch, M.S. (2018) Morphological divergence of the Threatened Rocky Mountain sculpin (Cottus sp.) is driven by biogeography and flow regime. Aquatic Conservation: Marine and Freshwater Ecosystems 28: 78-86.

Abstract

Stream hydrology is considered the primary factor in structuring freshwater fish communities,influencing stream habitats, food resources, and life‐history characteristics. Changes in stream hydrology, from climate change and anthropogenic sources (e.g. dams, irrigation channels), are thought to have adverse impacts on many freshwater species. The Rocky Mountain Sculpin (Cottus sp.) is a threatened species in Canada. Phenotypes of Rocky Mountain Sculpin were compared across a gradient of four streams differing in stream hydrology. It was hypothesized that Rocky Mountain Sculpin would show body forms minimizing drag in higher flow environments. Using geometric morphometrics and meristic counts, body shape, fin rays, and sensory pores were compared. As hypothesized, high‐flow river systems were correlated with sculpin with more dorso‐ventrally compressed, slender body shapes that minimized resistance to flow (P<0.001). Rocky Mountain Sculpin had more pectoral fin rays in populations with higher flows than lower flows,potentially allowing them to increase friction when gripping onto the substrate (P<0.001), and more anteriorly and dorsally located head pores to improve detection of floating prey (P<0.001). Biogeographic isolation and difference in flow regime were the likely basis for the observed morphological variation. The degree to which these phenotypes become fixed is unknown;however, since phenotypic diversity parallels genetic diversity in Rocky Mountain Sculpin,there is the possibility that persistent selection of these phenotypes can make it difficult to adapt to rapidly changing habitat conditions, such as changing flow. This study emphasizes the importance of considering phenotypic and morphological variation when evaluating how best to mitigate anthropogenic stressors and their impact on freshwater fishes.

Citation: Rudolfsen, T.*, Watkinson, D. and Poesch, M.S. (2018) Morphological divergence of the Threatened Rocky Mountain sculpin (Cottus sp.) is driven by biogeography and flow regime. Aquatic Conservation: Marine and Freshwater Ecosystems 28: 78-86.

Flow Regime across the range of Rocky Mountain Sculpin

Morphological Differences Across Populations (Dorsal view) of Rocky Mountain Sculpin

Also Read:

Rudolfsen, T.*, Ruppert, J.W.R.*, Davis, C., Taylor, R., Watkinson, D. and M.S. Poesch (2019) Habitat use and hybridization between the Rocky Mountain Sculpin (Cottus sp.) and Slimy Sculpin (Cottus cognatus). Freshwater Biology 64(3): 391-404.

* Lab members: Tyana Rudolfsen, Mark Poesch. Check out opportunities in the lab!

Veillard, M.F., Ruppert, J.L.W., Tierney, K., Watkinson, D., and M.S. Poesch. (2017) Comparative swimming and station-holding ability of the threatened Rocky Mountain Sculpin (Cottus sp.) from four hydrologically distinct rivers. Conservation Physiology 5: 1-12.

Abstract:

Hydrologic alterations, such as dams, culverts or diversions, can introduce new selection pressures on freshwater fishes, where they are required to adapt to novel environmental conditions. Our study investigated how species adapt to natural and altered stream flow, where we use the threatened Rocky Mountain Sculpin (Cottus sp.) as a model organism. We compared the swimming and station-holding performance of Rocky Mountain Sculpin from four different hydrologic regimes in Alberta and British Columbia, including the North Milk River, a system that experiences increased flows from a large-scale diversion. We measured the slip (U_slip) and failure (U_burst) velocities over three constant acceleration test trials. U_slipwas defined as the point at which individuals required the addition of bursting or swimming to maintain position. U_burst was defined as the point at which individuals were unable to hold position in the swimming chamber through swimming, bursting or holding techniques without fully or partially resting on the electrified back plate. We found individuals from the Flathead River in British Columbia (with the highest natural flow) failed at significantly higher U_burstvelocities than fish from the southern Albertan populations. However, there was no relationship between peak hydrologic flow from the natal river and U_burst or U_slip. Further, U_burst velocities decreased from 51.8 cm s⁻¹ (7.2 BL s⁻¹) to 45.6 cm s⁻¹ (6.3 BL s⁻¹) by the third consecutive test suggesting the use of anaerobic metabolism. U_slip was not different between trials suggesting the use of aerobic metabolism in station-holding behaviours (U_slip). Moreover, we found no significant differences in individuals from the altered North Milk River system. Finally, individual caudal morphological characteristics were related to both slip and failure velocities. Our study contributes to the conservation of Rocky Mountain Sculpin by providing the first documentation of swimming and station-holding abilities of this benthic fish.

Citation: Veillard, M.F.*, Ruppert, J.L.W.*, Tierney, K., Watkinson, D., and Poesch, M.S. 2017. Comparative swimming and station-holding ability of the threatened Rocky Mountain Sculpin (Cottus sp.) from four hydrologically distinct rivers. Conservation Physiology 5: 1-12.

Difference in Swim Performance Across Populations of Rocky Mountain Sculpin. Shown are Tukey contrasts (estimate +/- 95% confidence intervals) between rivers (top row) and constant acceleration trial (CAT) numbers (bottom row) for failure (Uburst) and slip (Uslip) velocities from linear effects model. Significant differences are noted in yellow; Rivers are abbreviated as: Flathead River (FH), St. Mary River (SM), Lee Creek (LC) and North Milk River (NM).

Also Read:

Rudolfsen, T.*, Watkinson, D. and Poesch, M.S. (2018) Morphological divergence of the Threatened Rocky Mountain sculpin (Cottus sp.) is driven by biogeography and flow regime. Aquatic Conservation: Marine and Freshwater Ecosystems 28: 78-86.

*Lab members: Marie Veillard, Jonathan Ruppert, Mark Poesch. Check out opportunities in the lab!

Ruppert, J.L.W., James, P.M.A., Taylor, R., Rudolfsen, T., Veillard, M.*, Davis, C., Watkinson, D. and Poesch, M.S. (2017) Riverscape genetic structure of a threatened and dispersal limited freshwater species, the Rocky Mountain Sculpin (Cottus sp.). Conservation Genetics 18: 925-937.

Abstract:

Understanding the movement ability and the spatial scale(s) of population genetic structure of species can together better ‘tune’ management objectives to prevent potential range contraction and population declines. We studied the Rocky Mountain Sculpin (Cottus sp.), a threatened species in Canada, to demonstrate the utility of using two complementary approaches to assess connectivity of a species. To do so, we used Passive Integrated Transponder (PIT) tags with a stationary tracking array (n = 223) to track movement and genetic data (n = 1,015) from nine microsatellite loci to assess genetic population structure. The PIT tag results indicated that Rocky Mountain Sculpin are sedentary; approximately 50% of individuals only moved a maximum distance of 10 meters (upstream or downstream) over a 5-month period. Genetic analyses indicated that at the spatial scale of our study area (5500 km2), watershed structure (river basins) is the main geographic feature influencing population genetic structure. We used the Bayesian clustering tool STRUCTURE, which suggested four distinct sub-populations of Rocky Mountain Sculpin in Canada. Genetic structure at finer spatial scales (within basins and sub-basins) appears to be influenced by fluvial distance (i.e., geographic distance along a river) and elevation change between sample locations (i.e., isolation-by-distance and isolation-by-environment). Combining movement and genetic analyses provides complimentary evidence of limited dispersal in Rocky Mountain Sculpin and highlights that both approaches together can provide broader insight into connectivity between populations that may ultimately help to aid future management decisions.

Citation: Ruppert, J.L.W.*, James, P.M.A., Taylor, R., Rudolfsen, T.*, Veillard, M.*, Davis, C., Watkinson, D. and Poesch, M.S. 2017. Riverscape genetic structure of a threatened and dispersal limited freshwater species, the Rocky Mountain Sculpin (Cottus sp.). Conservation Genetics 18: 925-937.

STRUCTURE results showing mean assignment of individuals into four clusters and sorted by geographic locatoins. Geographic locations are abbreviated as FH: Flathead River, LC: Lee Creek, STM: St Mary River and NM: North Milk River.

Also Read:

Nelson-Chorney, H.*, Carli, C.M., Davis, C.S., Vinebrooke, R.D., Poesch, M.S., and M.K. Taylor (2019) Environmental DNA in lake sediment reveals biogeography of native genetic diversity. Frontiers in Ecology and Evolution 17: 313-318.

*Lab members: Jonathan Ruppert, Tyana Rudolfsen, Marie Veillard, Mark Poesch. Check out opportunities in the lab!

Neufeld, K.*, Watkinson, D., and Poesch, M.S. (2016) The effect of hydrologic alteration on capture efficiency of freshwater fishes in a highly modified Prairie stream: Implications for bio-monitoring programs. River Research and Applications 32: 975-983.

Citation: Neufeld, K.*, Watkinson, D., and Poesch, M.S. (2016) The effect of hydrologic alteration on capture efficiency of freshwater fishes in a highly modified Prairie stream: Implications for bio-monitoring programs. River Research and Applications 32: 975-983.

Abstract

Hydrology is a defining feature of aquatic ecosystems. Changes in stream hydrology, due to climate change, water use and impoundment, have been shown to negatively affect fish populations. Assessing changes in hydrology and its effect on fish populations and communities remains an important consideration for aquatic monitoring programmes across the globe. In this study, we used the Milk River in southern Alberta as a model system to understand how hydrologic alteration may also affect capture probabilities of fishes and impact instream monitoring programmes. The Milk River receives the majority of its April to October flow via an inter-basin transfer from the St. Mary River, drastically altering the hydrologic regime and instream habitats for fishes during this augmentation period. We estimated species-specific seine net capture probabilities of fishes in the Milk River during augmentation and natural flow periods using depletion surveys in both open and enclosed sites. Using habitat data collected during the seine surveys, linear mixed-effects models were created with capture efficiency as the dependent variable. Models were compared using corrected Akaike’s information criterion, and the relative contributions of the different variables to the top models were examined. We found that species and flow characteristics, such as water velocity and the state of augmentation, played a prominent role in many of the top models explaining variation in capture efficiency. These results demonstrate that changes to stream hydrology clearly have the potential to impact gear efficiency and individual species assessments. Stream monitoring programmes, which aim to determine long-term trends in aquatic ecosystem health, need to be mindful that any change to stream hydrology—from climate change, fragmentation or stream alteration—can alter capture efficiency of the sampling gear and inadvertently alter species-specific trends.

*Lab members: Kenton Neufeld, Mark Poesch. Check out opportunities in the lab!

Seine net capture probability for Flathead Chub, Longnose Dace, Sucker species, and Western Silvery Minnow in the Milk River in southern Alberta during augmented and natural flow conditions, and from open and closed surveys.