Nicholas E. Jones

Incorporating lakes within the river discontinuum: longitudinal changes in ecological characteristics in stream-lake networks

Lakes and rivers are intimately connected in an alternating series of lentic and lotic reaches in many regions. The study of lakes and their outlets in hierarchical and branching river networks has not gained the attention of stream ecologists, and little effort has been focused on synthesizing the ecology of lake–stream interactions within a drainage network. Rapid and predictable changes in the ecological characteristics of streams occur at the interface with lakes. The influence that a lake might have on a stream is dependent on its position within the stream, stream type and size, lake size and shape, and the inlet and outlet positions. Little is known about the influences of multiple lakes within stream–lake networks and how these influences are determined by network shape and pattern. Fruitful collaborations and novel insights will come from the combined efforts of limnologists, stream ecologists, and landscape ecologists. Geographic information systems and network analyses will play an important ro...

Evaluation of Single-Pass Electrofishing and Rapid Habitat Assessment for Monitoring Redside Dace

Abstract To date, monitoring of the status of the provincially threatened redside dace Clinostomus elongatus in Ontario has been ad hoc or incidental to other sampling programs. We evaluated the efficacy of single-pass backpack electrofishing without block nets to detect redside dace, provide an index of abundance, and characterize size-class distributions. We also examined whether a rapid stream habitat assessment method was suitable for monitoring habitat condition at redside dace sites. Based on 40 sites across 7 Lake Ontario tributaries, catch data and length frequency distributions from single-pass sampling were compared with those from multiple-pass depletion sampling. Single-pass electrofishing captured 47% of estimated redside dace abundance and 34% of biomass. Abundance and biomass data from the single-pass method were positively correlated (abundance r2 = 0.83; biomass r2 = 0.52) with estimates from the multiple-pass depletion method. Probability of detection and precision of single-pass estimat...

Enhancing Productive Capacity in the Canadian Arctic: Assessing the Effectiveness of Instream Habitat Structures in Habitat Compensation

Abstract We examined the effectiveness of physical habitat structures (ramps, V-weirs, vanes, and groins) at increasing the productive capacity of a newly created 3.4-km artificial stream in the Barrenlands region of the Northwest Territories, Canada. We quantified changes in fish density and growth in the immediate area of each structure and for the artificial stream as a whole using before–after–control–impact approaches. Emphasis was on young-of-the-year (hereafter, age-0) Arctic grayling Thymallus arcticus, the dominant fish in the artificial and nearby natural streams. Structures attracted significantly higher densities of fish than did nearby reference sections, yet the age-0 Arctic grayling at the structures did not experience any density-dependent reduction in growth, suggesting that structures provided energetically favorable microhabitats. Relative to reference streams and prestructure conditions, however, the addition of these physical structures did not increase the density, biomass, or growth...

Assessing the effectiveness of a constructed Arctic stream using multiple biological attributes.

Objective assessment of habitat compensation is a central yet challenging issue for restoration ecologists. In 1997, a 3.4-km stream channel, designed to divert water around an open pit diamond mine, was excavated in the Barrenlands region of the Canadian Arctic to create productive stream habitat. We evaluated the initial success of this compensation program by comparing multiple biological attributes of the constructed stream during its first three years to those of natural reference streams in the area. The riparian zone of the constructed stream was largely devoid of vegetation throughout the period, in contrast to the densely vegetated zones of reference streams. The constructed stream also contained lower amounts of woody debris, coarse particulate organic matter (CPOM), and epilithon; had lower coverage by macrophytes and bryophytes; and processed leaf litter at a lower rate than reference streams. Species richness and densities of macroinvertebrates were consistently lower in the constructed stream compared to natural streams. This contributed to differences in macroinvertebrate assemblage structure throughout the period, although assemblages showed some convergence by year 3. The effectiveness of the constructed stream to emulate natural streams varied somewhat depending on the biological attribute being evaluated. Assessments based on individual attributes showed that minimal to moderate levels of similarity between the constructed stream and natural streams were achieved. A collective assessment of all biological and ecosystem attributes suggested that the constructed stream was not a good surrogate for natural streams during these first years. Additional time would be required before many characteristics of the constructed stream would resemble those of reference streams. Because initial efforts to improve fish habitat in the constructed stream focused on physical structures (e.g., weirs, vanes, rock, groins), ecological factors limiting fish growth were not considered and likely constrained success. We suggest that a greater focus on organic characteristics and vegetation within the stream and its riparian zone could have accelerated compensation. The addition of woody debris and CPOM, combined with planting of shrubs and herbs along the stream, should provide a source of allochthonous matter for the biotic community while large cobble and boulders should improve the physical stability of stream system, protecting its organic components.

Selective feeding of age-0 Arctic grayling in lake-outlet streams of the Northwest Territories, Canada

A paucity of information exists on the diet of Arctic grayling, Thymallus arcticus, particularly for young-of-the-year (YOY). We examined the diet of YOY Arctic grayling in relation to food availability, in the Barrenlands region of the Northwest Territories, Canada, where lake-outlet streams serve as nursery habitat for these fish. Given the small size of YOY grayling and the abundance of lake-derived microcrustacea in the drift of these lake-outlet streams, we anticipated that these prey would make up a major component of the YOYs diet. Food selectivity by YOY grayling, however, was strongly sized-biased; although microcrustacea dominated the drift, YOY primarily consumed larger taxa, especially Chironomidae and Simuliidae. Even among these taxa, grayling tended to select the larger individuals. As they grew, YOY grayling took larger numbers of both large and small prey, particularly the larger invertebrates, although prey size range did not change after mid-July. Selection of pupae and avoidance of Ephemeroptera suggest that prey characteristics other than size also contribute to selectivity by YOY grayling. The relatively limited consumption of terrestrial invertebrates and other large prey may reflect the small sizes of fish in this arctic study, as well as differences in prey availability. Despite the abundance of lake-derived prey, instream production of invertebrates should largely determine the productive capacity of Barrenlands streams as fish habitat.

Variation in Acute Thermal Tolerance within and among Hatchery Strains of Brook Trout

Abstract The ability of coldwater species and populations to respond to temperature increases associated with climate change will depend on the existing adaptive potential within and among populations. Brook trout Salvelinus fontinalis is a valued coldwater species that has been widely stocked across its native range as well as extensively introduced in western North America. We investigated the thermal tolerance of the three primary brook trout hatchery strains used in Ontario (Dickson Lake, Lake Nipigon, and Hills Lake strains) and the thermal tolerance of a brook trout subspecies, Aurora trout S. fontinalis timagamiensis; all strains were reared in a common hatchery environment. In addition to comparing the strains’ responses to acute thermal stress, we also examined variability in temperature tolerance among families within several of these strains. Evidence for significant differences in temperature tolerance was observed both within and among the strains, with Aurora trout showing the least capacit...

The Impacts of Atlantic Salmon Stocking on Rainbow Trout in Barnum House Creek, Lake Ontario

ABSTRACT We compared the impacts of stocking age-0 Atlantic salmon (Salmo salar) at high and low densities, and no stocking on abundance and growth of age-0 rainbow trout (Oncorhyncus mykiss) in Barnum House Creek, Ontario during 1993 to 2005. A similar stream, Shelter Valley Creek, was chosen as an appropriate reference stream where age-0 Atlantic salmon were not stocked. The catches of age-0 rainbow trout in Barnum House and the reference stream were highly correlated (r = 0.96) during years when no stocking occurred; however, this relationship did not persist in years when Atlantic salmon were stocked. The catch of age-0 rainbow trout in Barnum House Creek was significantly lower under both high (P = 0.00026) and low (P = 0.011) density Atlantic salmon stocking treatments compared with the no stocking treatment. The catches of age-0 rainbow trout and age-0 Atlantic salmon were negatively correlated in Barnum House Creek (r = −0.63). The length of age-0 rainbow trout in Barnum House Creek was depressed significantly (P = 0.004), under the high intensity Atlantic salmon stocking treatment, but not under the low intensity treatment (P = 0.20). In contrast, the length of age-0 rainbow trout in Shelter Valley Creek was unchanged over the same period. Restoration stocking of Atlantic salmon in Lake Ontario tributaries may impact rainbow trout abundance and growth.

Evaluation of a Simple Method to Classify the Thermal Characteristics of Streams Using a Nomogram of Daily Maximum Air and Water Temperatures

Abstract This study assessed the applicability of an existing methodology to classify different stream sites into coldwater, coolwater, or warmwater areas based on their maximum air and water temperatures in summer. Using this methodology, single measurements of daily maximum air temperatures (≥24.5°C) and water temperatures at 1600 hours between July 1 and September 7 can be plotted on a nomogram to approximate the thermal classification of a site. Data from 122 sites throughout the Great Lakes basin, Ontario, indicated that the existing methodology should be revised to include sampling days from July 1 to August 31 instead of July 1 to September 7 and daily sampling periods between 1600 and 1800 hours as opposed to 1600 hours to capture the warmest temperatures at the sites. Data from 80 of the 122 sites consistently fell into the coldwater, coolwater, or warmwater categories. Data from 5 sites overlapped the coldwater and coolwater categories, whereas data from 37 sites overlapped the coolwater and war...

Evaluation of Current Approaches to Stream Classification and a Heuristic Guide to Developing Classifications of Integrated Aquatic Networks

Abstract Conservation and management of fresh flowing waters involves evaluating and managing effects of cumulative impacts on the aquatic environment from disturbances such as: land use change, point and nonpoint source pollution, the creation of dams and reservoirs, mining, and fishing. To assess effects of these changes on associated biotic communities it is necessary to monitor and report on the status of lotic ecosystems. A variety of stream classification methods are available to assist with these tasks, and such methods attempt to provide a systematic approach to modeling and understanding complex aquatic systems at various spatial and temporal scales. Of the vast number of approaches that exist, it is useful to group them into three main types. The first involves modeling longitudinal species turnover patterns within large drainage basins and relating these patterns to environmental predictors collected at reach and upstream catchment scales; the second uses regionalized hierarchical classification to create multi-scale, spatially homogenous aquatic ecoregions by grouping adjacent catchments together based on environmental similarities; and the third approach groups sites together on the basis of similarities in their environmental conditions both within and between catchments, independent of their geographic location. We review the literature with a focus on more recent classifications to examine the strengths and weaknesses of the different approaches. We identify gaps or problems with the current approaches, and we propose an eight-step heuristic process that may assist with development of more flexible and integrated aquatic classifications based on the current understanding, network thinking, and theoretical underpinnings.

Do existing ecological classifications characterize the spatial variability of stream temperatures in the Great Lakes Basin, Ontario?

ABSTRACT Ecological classifications of stream ecosystems have been used to develop monitoring programs, identify reference and impacted systems, and focus conservation efforts. One of the most influential, but highly variable, components of stream ecosystems is water temperature but few geographically broad-scale and long-term programs exist to assess and monitor temperatures. This study evaluated if existing ecological classifications could be used to categorize the similarities and differences in stream temperatures across the Ontario portion of the Great Lakes Basin. Concordance between the spatial variability in temperatures and an existing ecological classification would support the use of that classification to define areas with similar temperatures, guide the development of a monitoring program, and inform management programs. The five classifications evaluated were the ecoregions and ecodistricts defined in the National Ecological Framework for Canada, the ecoregions and ecodistricts defined in the Ecological Land Classification of Ontario, and the aquatic ecosystem units defined in the Aquatic Ecosystem Classification (AEC) for the Ontario portion of the Great Lakes Basin. Hierarchical linear modelling and corrected Akaike Information Criterion indicated that the ecodistrict classifications characterized more of the spatial variability in temperatures than the ecoregion and AEC classification but temperatures were more variable among sites within classes than between classes. Therefore, none of the existing ecological classifications could be used to characterize thermal variability. Future research should examine if the inability of the existing classifications to capture the thermal variability translates into inaccurate classification of other ecosystem components such as water quality, and macroinvertebrate and fish assemblages.