Summer stream habitat preferences of Nunavik anadromous Arctic char (Salvelinus alpinus) fry and parr

Arctic char is a fish species known to occupy diverse habitats within the Arctic region. However, summer habitat use during the juvenile stage of the anadromous form is largely unknown. The present study aims to characterize fry and parr summer habitat preferences. Surveys were conducted by electrofishing, associated with physical habitat characterization on several rivers of the Ungava Bay, Nunavik, Canada. At the microhabitat and station scales, fry showed significant habitat preferences for shallow water and slow velocity. At the mesohabitat scale, fry showed a significant habitat selectivity for riffles. This habitat selectivity implies that habitat models can be built to evaluate the potential of habitat suitability for Arctic char fry. However, no significant habitat selectivity was found for parr. Parr size was nonetheless positively correlated with velocity, which was found to be a limitative factor for juvenile habitat use. This first attempt at modeling juvenile anadromous Arctic char habitat in rivers emphasizes the importance of selecting an appropriate spatial scale and reiterates the fact that parr showed relatively high plasticity in stream habitat selection.

Quantifying ecological effects of sedimentation in streams in differing land use management zones

<p>This ecological and geomorphological assessment of Horokiri Stream and Ration Creek was conducted across four longitudinal zones to explore the effects of sediment delivery, run-off, channel form, riparian and in-stream habitat. The Horokiri Stream channel has moved approximately 7 metres westward over the last 20 years, with both banks now covered in long grass, flaxes, natives with a mix of tall canopy trees. Looking at stream, Spearman’s for Ration at Figure 27 (n = 16, rho -0.243, p = 0.36) as deposited sediment increased, MCI decreased, non-significant. Spearman’s for Horokiri at Figure 28 (n = 16, rho 0.247, p = 0.35) as MCI increased with sediment, non-significant. Results from upstream of the riparian zones showed more deposited fine sediment. However, within both the riparian zones the sediment deposition was much lower. The native riparian planting along the stream banks had a positive effect on reducing sedimentation. The findings support the concept that the restoration of riparian zones with buffer widths exceeding 10 metres can improve stream habitat and invertebrate health. There was no relationship between flow and deposition rate P(X2>241.84) = 0.24. Figure 24 shows deposited sediment on MCI depending on land use groups (X2 = 11.81, df = 4, p = 0.019). No statistically significant differences were found (comparing the effect of sediment between different land use management groups). An experiment investigated a disturbance hypothesis in both Ration Creek and Horokiri Stream was conducted during February 2019. The experiment was designed to be long enough to study the effects of four weekly pulse flushing events created by scrapping the stream bed with a drain drag tool and the effects of a press sustained disturbance on the macroinvertebrate community. I measured the sediment and the macroinvertebrate captured in each trap within the experiment site every seven days. My prediction was that macroinvertebrate communities subject to sustained fine sediment delivery (press disturbance) are affected by simulated pulse flushing events (pulse disturbance). A comparison of sediment depositional rate before and after the manipulative experiment (Figure 36) showed higher sediment deposition after the pulse flushing events (1.55 W/A/D) compared to before during the assessment phase (0.88 W/A/D) in Horokiri (t = 2.35, df = 8.95, p = 0.04), but no significant difference before (1.57 W/A/D) or after (1.38 W/A/D) in Ration (t = -0.818, df = 7.71, p = 0.44). It appeared that the smaller riparian buffer width of 2-5m at Ration Creek did not limit sediment deposition. The effects of sediment disturbance in the experiment reflect the rapid ability of macroinvertebrates to respond to sediment by drifting out of unsuitable areas. The weekly pulse disturbance events resulted in increased sediment deposition compared to the background levels of sediment deposition (indicative of a press disturbance) in both streams. As pulse disturbance events increased, the number of macroinvertebrate taxa decreased. Horokiri Stream invertebrate communities declined by 33% compared to Ration Creek which declined by 50%.</p>

Quantifying ecological effects of sedimentation in streams in differing land use management zones

<p>This ecological and geomorphological assessment of Horokiri Stream and Ration Creek was conducted across four longitudinal zones to explore the effects of sediment delivery, run-off, channel form, riparian and in-stream habitat. The Horokiri Stream channel has moved approximately 7 metres westward over the last 20 years, with both banks now covered in long grass, flaxes, natives with a mix of tall canopy trees. Looking at stream, Spearman’s for Ration at Figure 27 (n = 16, rho -0.243, p = 0.36) as deposited sediment increased, MCI decreased, non-significant. Spearman’s for Horokiri at Figure 28 (n = 16, rho 0.247, p = 0.35) as MCI increased with sediment, non-significant. Results from upstream of the riparian zones showed more deposited fine sediment. However, within both the riparian zones the sediment deposition was much lower. The native riparian planting along the stream banks had a positive effect on reducing sedimentation. The findings support the concept that the restoration of riparian zones with buffer widths exceeding 10 metres can improve stream habitat and invertebrate health. There was no relationship between flow and deposition rate P(X2>241.84) = 0.24. Figure 24 shows deposited sediment on MCI depending on land use groups (X2 = 11.81, df = 4, p = 0.019). No statistically significant differences were found (comparing the effect of sediment between different land use management groups). An experiment investigated a disturbance hypothesis in both Ration Creek and Horokiri Stream was conducted during February 2019. The experiment was designed to be long enough to study the effects of four weekly pulse flushing events created by scrapping the stream bed with a drain drag tool and the effects of a press sustained disturbance on the macroinvertebrate community. I measured the sediment and the macroinvertebrate captured in each trap within the experiment site every seven days. My prediction was that macroinvertebrate communities subject to sustained fine sediment delivery (press disturbance) are affected by simulated pulse flushing events (pulse disturbance). A comparison of sediment depositional rate before and after the manipulative experiment (Figure 36) showed higher sediment deposition after the pulse flushing events (1.55 W/A/D) compared to before during the assessment phase (0.88 W/A/D) in Horokiri (t = 2.35, df = 8.95, p = 0.04), but no significant difference before (1.57 W/A/D) or after (1.38 W/A/D) in Ration (t = -0.818, df = 7.71, p = 0.44). It appeared that the smaller riparian buffer width of 2-5m at Ration Creek did not limit sediment deposition. The effects of sediment disturbance in the experiment reflect the rapid ability of macroinvertebrates to respond to sediment by drifting out of unsuitable areas. The weekly pulse disturbance events resulted in increased sediment deposition compared to the background levels of sediment deposition (indicative of a press disturbance) in both streams. As pulse disturbance events increased, the number of macroinvertebrate taxa decreased. Horokiri Stream invertebrate communities declined by 33% compared to Ration Creek which declined by 50%.</p>

Occupancy of young-of-year Arctic grayling (Thymallus arcticus) in Barrenland streams

Arctic grayling (Thymallus arcticus) is an iconic fish species that is present across the remote subarctic Barrenlands, yet our lack of understanding of their distributional patterns constrains predictions of anthropogenic effects on Barrenland populations. These adfluvial fish rely on seasonal lake-stream connections to migrate, spawn, and rear. We address knowledge gaps on what Barrenland stream attributes are suitable for rearing young-of-year Arctic grayling. Visual surveys of young-of-year Arctic grayling were conducted in 48 streams near Baker Lake, Nunavut, Canada. Occupancy modeling was used to relate stream habitat and landscape variables to fish presence/absence. The best predictors of occupancy were total area of contributing upstream lakes and landcover (upland/lowland); stream basins with larger contributing upstream lake area and more lowland cover were more likely to be occupied. Results suggest that occupancy reflects reliability of stream connectivity throughout the open water season and across years. The occupancy model developed here can adequately predict stream suitability for young-of-year Arctic grayling using lake area and land classification data that are remotely accessed. This may lessen the considerable financial and logistical constraints of conducting field research on Arctic grayling in the vast Barrenlands and facilitate more directed field programs to inform conservation and mitigation plans.

Wadeable stream habitat monitoring at Congaree National Park: 2018 baseline report

The Southeast Coast Network (SECN) Wadeable Stream Habitat Monitoring Protocol collects data to give park resource managers insight into the status of and trends in stream and near-channel habitat conditions (McDonald et al. 2018a). Wadeable stream monitoring is currently implemented at the five SECN inland parks with wadeable streams. These parks include Horseshoe Bend National Military Park (HOBE), Kennesaw Mountain National Battlefield Park (KEMO), Ocmulgee Mounds National Historical Park (OCMU), Chattahoochee River National Recreation Area (CHAT), and Congaree National Park (CONG). Streams at Congaree National Park chosen for monitoring were specifically targeted for management interest (e.g., upstream development and land use change, visitor use of streams as canoe trails, and potential social walking trail erosion) or to provide a context for similar-sized stream(s) within the park or network (McDonald and Starkey 2018a). The objectives of the SECN wadeable stream habitat monitoring protocol are to: Determine status of upstream watershed characteristics (basin morphology) and trends in land cover that may affect stream habitat, Determine the status of and trends in benthic and near-channel habitat in selected wadeable stream reaches (e.g., bed sediment, geomorphic channel units, and large woody debris), Determine the status of and trends in cross-sectional morphology, longitudinal gradient, and sinuosity of selected wadeable stream reaches. Between June 11 and 14, 2018, data were collected at Congaree National Park to characterize the in-stream and near-channel habitat within stream reaches on Cedar Creek (CONG001, CONG002, and CONG003) and McKenzie Creek (CONG004). These data, along with the analysis of remotely sensed geographic information system (GIS) data, are presented in this report to describe and compare the watershed-, reach-, and transect-scale characteristics of these four stream reaches to each other and to selected similar-sized stream reaches at Ocmulgee Mounds National Historical Park, Kennesaw Mountain National Battlefield Park, and Chattahoochee National Recreation Area. Surveyed stream reaches at Congaree NP were compared to those previously surveyed in other parks in order to provide regional context and aid in interpretation of results. edar Creek’s watershed (CONG001, CONG002, and CONG003) drains nearly 200 square kilometers (77.22 square miles [mi2]) of the Congaree River Valley Terrace complex and upper Coastal Plain to the north of the park (Shelley 2007a, 2007b). Cedar Creek’s watershed has low slope and is covered mainly by forests and grasslands. Cedar Creek is designated an “Outstanding Resource Water” by the state of South Carolina (S.C. Code Regs. 61–68 [2014] and S.C. Code Regs. 61–69 [2012]) from the boundary of the park downstream to Wise Lake. Cedar Creek ‘upstream’ (CONG001) is located just downstream (south) of the park’s Bannister Bridge canoe landing, which is located off Old Bluff Road and south of the confluence with Meyers Creek. Cedar Creek ‘middle’ and Cedar Creek ‘downstream’ (CONG002 and CONG003, respectively) are located downstream of Cedar Creek ‘upstream’ where Cedar Creek flows into the relatively flat backswamp of the Congaree River flood plain. Based on the geomorphic and land cover characteristics of the watershed, monitored reaches on Cedar Creek are likely to flood often and drain slowly. Flooding is more likely at Cedar Creek ‘middle’ and Cedar Creek ‘downstream’ than at Cedar Creek ‘upstream.’ This is due to the higher (relative to CONG001) connectivity between the channels of the lower reaches and their out-of-channel areas. Based on bed sediment characteristics, the heterogeneity of geomorphic channel units (GCUs) within each reach, and the abundance of large woody debris (LWD), in-stream habitat within each of the surveyed reaches on Cedar Creek (CONG001–003) was classified as ‘fair to good.’ Although, there is extensive evidence of animal activity...

Near-Term Changes to Reach Scale Habitat Features Following Headwater Stream Restoration in a Southeastern Massachusetts Former Cranberry Bog

Land use changes remain one of the leading global change drivers leading to biodiversity loss in terrestrial and aquatic systems. Restoration aims to counteract the development of “natural” (i.e., forested, grassland, or wetland) spaces that alter and fragment the landscape and reduce local biodiversity through direct impacts to the water column and indirect impacts which inhibit adult dispersal of aquatic insects. This case study seeks to determine if a large-scale restoration of a former cranberry bog in Plymouth, MA has resulted in near-term measurable changes to the composition, structure, and function of local-scale in-stream habitat diversity. A three-year observational field study beginning one year prior to reconstruction was conducted at the restored cranberry bog and at two control treatment sites: an active cranberry bog reference and a least impacted reference (i.e., has never been used for modern agriculture). Seasonal inventories of in-stream habitat features including depth, substrate, macrohabitat, and in-stream cover were taken from 2015 to 2017. We found that 2 years post-restoration, there was no significant evidence of compositional or functional change, while there was a significant increase in structural diversity. There is reason to suspect the system is still in flux and longer-term monitoring may detect future habitat heterogeneity alterations.

Effects of a diatom ecosystem engineer (Didymosphenia geminata) on stream food webs: implications for native fishes

Stream habitat changes affecting primary consumers often indirectly impact secondary consumers such as fishes. Blooms of the benthic algae Didymosphenia geminata (Didymo) are known to affect stream macroinvertebrates, but the potential indirect trophic impacts on fish consumers are poorly understood. In streams of the Kootenai River basin, we quantified the diet, condition, and growth rate of species of trout, char, and sculpin. In 2018, macroinvertebrate taxa composition was different between a stream with Didymo and a stream without, but trout diets, energy demand, and growth rates were similar. Trout abundance was higher in the stream with Didymo, but the amount of drifting invertebrates was higher in the stream without. In 2019, we surveyed 28 streams with a gradient of coverage. Didymo abundance was correlated only with the percentage of aquatic invertebrates in trout diets and was not related to diets of char or sculpin or condition of any species. Thus, we found no evidence for a trophic link between Didymo blooms and the condition or growth of trout, char, or sculpin in mountainous headwater streams.