Small Boreal Lakes Research Articles

Potential Effects of Climate Warming on Fish Habitats in Temperate Zone Lakes with Special Reference to Lake 239 of the Experimental Lakes Area (ELA), North-Western Ontario

We used simple statistics (e.g. mean temperature, degree days, cumulative volume days) to describe present thermal habitats for cool water (yellow perch, Perca flavescens) and cold water (lake trout, Salvelinus namaycush) fish of a small boreal lake. We then modelled changes in the vertical and temporal extent of these habitats under various scenarios of climatic change that included increases in air temperature of 2°C, 4°C, and 9°C, and positive and negative deviations from present levels of 10% in solar radiation and relative humidity, and 20% in wind speed and the lake water extinction coefficient. Model simulations indicated pronounced changes in the temporal and vertical availability of fish thermal niche space. These changes were mainly driven by the large increases in mean mixed layer temperatures that corresponded to ∼85% of the increases in air temperature, but, in particular, changes in light attenuation also resulted in some non-linear, unexpected effects in the distribution and seasonal availability of thermal niche space. As expected, ‘classical’ lake trout thermal habitat (5–15°C) was progressively reduced and almost disappeared in littoral areas in spring and early summer. Perch thermal niche space expanded for air temperature increases of up to 4°C, but largely disappeared for the 9°C increase. We discuss changes in thermal habitat with regard to the life history of lake trout and yellow perch, and include other determinants of fish habitat to evaluate the potential of these species for long-term ecological success under climatic warming.

Development of a prediction system for lake stony-bottom littoral macroinvertebrate communities

Assessing the biological integrity of aquatic habitats often requires a comparison of observed conditions with those conditions expected to occur in the absence of human-generated stress. Using data from least impaired lakes, models were developed to predict the macroinvertebrate community composition of stony littoral habitats of relatively small (median surface area = 0.26 km 2 ) boreal lakes. In brief, three steps were used in model calibration: (i) identification of biological groups by clustering, (ii) selection of environmental variables that explain among-group variance using ordination, and (iii) model calibration using discriminant function analysis RIVPASC-type predictive models were individually developed for the three major regions of Sweden; namely, the mixed forest, coniferous forest and arctic/alphine regions. Geographic position (latitude, longitude, altitude) and variables indicative of substratum (e.g. cobble and vegetation type) and water color were often found to discriminate among-group variance and were used in model calibrations. The lowest errors associated with observed to expected (O/E) scores for taxon richness were found for models developed for the mixed forest region (mean O/E score = 0.997 ± 0.254, CV = 25.5 %), and the highest errors were associated with models developed for the arctic/alpine region ((mean O/E score = 1.011 ± 0.337, CV = 33.3 %). The use of RIVPACS-type models in ecological assessment is increasing, principally because the site-specific predictions that are produced are intuitive and rather straightforward. This study shows that the RIVPACS approach may be used for assessing and monitoring the ecological quality of boreal lake ecosystems using littoral macroinvertebrate communities.

Potential impacts of clearcutting on parasites of minnows in small boreal lakes.

Clearcutting and deforestation lead to increased erosion, increased water temperature, altered water chemistry, and modified watershed hydrology in aquatic systems. Effects on biological organisms have been documented for phytoplankton, zooplankton, benthos, and fish. In this study, parasites of the northern redbelly dace, Phoxinus eos (Cope), were examined from an experimental area consisting of headwater lakes and their watersheds in the boreal forest of Ontario, Canada prior to and after clearcutting around the lakes. Catchments of two lakes were heavily, and one lake partially, clearcut in 1996, and that of a fourth lake was untouched. In 1993, three years prior to clearcutting, five taxa of parasites, including the monogeneans Dactylogyrus sp. and Gyrodactylus sp., metacercaria of the digenean Clinostomum complanatum (Rudolphi, 1819), the nematode Rhabdochona canadensis Moravec et Arai, 1971 and the myxozoan Myxobolus sp. were found in or on northern redbelly dace. In 1998, two years after clearcutting, eight taxa were found on northern redbelly dace, including all of the above plus the digeneans Allocreadium sp. and Ornithodiplostomum ptychocheilus (Faust, 1917) and the copepod Ergasilus lizae Krøyer, 1863. Mean infracommunity species richness and the maximum number of species per fish were higher in the control and partially cut lake than in the heavily logged lakes. Uninfected fish were found in the heavily cut lakes, but not in the other lakes. Thus, disturbance may reduce parasite infracommunity complexity. Among individual parasite species, R. canadensis was absent from the two most heavily clearcut lakes and abundant in the two other lakes in 1998. Clearcutting may have affected the abundance of certain invertebrates in these lakes, in particular the mayflies that serve as intermediate hosts for R. canadensis. The parasites Allocreadium sp., O. ptychocheilus, and E. lizae have not been previously reported in or on northern redbelly dace.

Joint variation of zooplankton and seston stoichiometry in lakes and reservoirs

Summary We tested several stoichiometric hypotheses for thejoint dependence in element ratios in zooplanktonand their resources using direct chemical measure-ments of zooplankton (>80 µm) and seston. Our fivefield sites included three small boreal lakes, a warmwater reservoir and Lake Superior. Zooplankton ele-ment pools were generally not large compared to thetotal seston. We found a tight homeostasis in bulkzooplankton element ratios compared to theirresources. Weak correlations consistent with stoichi-ometric hypotheses were seen. Zooplankton C:P andC:N were very slightly positively correlated withseston ratios, but the zooplankton N:P ratio wasnegatively correlated with the same ratio in theseston. Acknowledgements Financial support came from the National ScienceFoundation, NOAA, and the University of Minne-sota. Fig. 3. Expansion of the vertical scale of Fig. 2A.Horizontal dotted lines indicate reported values ofC:P for a high and a low C:P zooplankton taxon(from S TERNER et al. 1992). The wavy line is a dis-tance-weighted least squares regression. The solidinclined line represents an hypothetical region ofexclusion (high seston C:P precludes dominance bylow C:P zooplankton).

Initial effects of catchment deforestation around small boreal forest lakes in northwestern Ontario, Canada

(2000). Initial effects of catchment deforestation around small boreal forest lakes in northwestern Ontario, Canada. SIL Proceedings, 1922-2010: Vol. 27, No. 2, pp. 1101-1107.

Identification of novel Archaea in bacterioplankton of a boreal forest lake by phylogenetic analysis and fluorescent in situ hybridization(1).

We report here on novel groups of Archaea in the bacterioplankton of a small boreal forest lake studied by the culture-independent analysis of the 16S rRNA genes amplified directly from lake water in combination with fluorescent in situ hybridization (FISH). Polymerase chain reaction products were cloned and 28 of the 160 Archaea clones with around 900-bp-long 16S rRNA gene inserts, were sequenced. Phylogenetic analysis, including 642 Archaea sequences, confirmed that none of the freshwater clones were closely affiliated with known cultured Archaea. Twelve Archaea sequences from lake Valkea Kotinen (VAL) belonged to Group I of uncultivated Crenarchaeota and affiliated with environmental sequences from freshwater sediments, rice roots and soil as well as with sequences from an anaerobic digestor. Eight of the Crenarchaeota VAL clones formed a tight cluster. Sixteen sequences belonged to Euryarchaeota. Four of these formed a cluster together with environmental sequences from freshwater sediments and peat bogs within the order Methanomicrobiales. Five were affiliated with sequences from marine sediments situated close to marine Group II and three formed a novel cluster VAL III distantly related to the order Thermoplasmales. The remaining four clones formed a distinct clade within a phylogenetic radiation characterized by members of the orders Methanosarcinales and Methanomicrobiales on the same branch as rice cluster I, detected recently on rice roots and in anoxic bulk soil of flooded rice microcosms. FISH with specifically designed rRNA-targeted oligonucleotide probes revealed the presence of Methanomicrobiales in the studied lake. These observations indicate a new ecological niche for many novel 'non-extreme' environmental Archaea in the pelagic water of a boreal forest lake.

Effects of experimental clearcut logging on water quality in three small boreal forest lake trout (<i>Salvelinus namaycush</i>) lakes

Water quality was monitored in three 30-ha stratified headwater Precambrian Shield lakes for 5 years before and 3 years after moderate to extensive catchment deforestation. These lakes, which had water renewal times of about a decade, showed only minor changes in water quality by the third year after logging. Water quality response in a lake with moderate deforestation and intact shoreline forest was similar to that in two lakes with extensive upland and shoreline deforestation. By the second and third years after logging, May-September average volume-weighted concentrations of dissolved organic carbon, chlorophyll, total nitrogen, K+, Cl-, and Si had all increased, generally by about 10-40% over predisturbance levels, while Ca2+ and Mg2+ had declined by 10-25%. Dry weather the first year after logging was associated with temporary declines of 10-20% in dissolved organic carbon and chlorophyll.

Movement and Habitat Use by Lake Whitefish during Spawningin a Boreal Lake: Integrating Acoustic Telemetry and Geographic Information Systems

Abstract To quantify lake whitefish swimming behavior, substrate selection, and the influence of water level variation on spawning behavior and success, we tracked lake whitefish Coregonus clupeaformis during two consecutive spawning seasons (October–November) in a small boreal lake in northwestern Ontario, Canada. The lake was subjected to an experimental drawdown of 1.4 m in 1995 and 0.75 m in 1996 at the time tracking started. We used a radio-linked, acoustic positioning system that produced positions every 100 s for 18 tagged lake whitefish, eight of which provided depth information. Fish position and depth were put into a geographic information system database with information on substratum, slope, and depth. Mean daily locomotor activity declined as the spawning season progressed. Two patterns of behavior occurred in both years. Offshore-oriented fish spent their time along bottom contours, which increased in depth through the spawning season. Inshore-oriented fish spent their time along the shoreli...

Intraspecific patterns of resource use by fathead minnows in a small boreal lake

An isolated, single-species assemblage of fathead minnows (Pimephales promelas) was studied to identify patterns of feeding and diel activity among three life-history groups (adult males, adult females, and juveniles). Minnows were collected from inshore and offshore stations during monthly (May–August) 24-h sampling periods. Minnows appeared flexible in their choice of food items, concentrating their feeding on invertebrate taxa, such as emerging chironomid pupae, that were temporarily available, as well as on relatively large and vulnerable microcrustaceans, such as Daphnia. Adult males, larger than females and juveniles, consumed the amphipod Hyallela azteca to a greater extent than the two smaller-bodied groups. Patterns of habitat use and activity were also consistent with behavioral flexibility. Prior to the breeding season, when all three groups were abundant, the population displayed intraspecific differences in diel activity; adults were typically active at night, when chironomid pupae were most abundant, whereas juveniles were primarily day active. Later, as catches of males declined, spatial and temporal patterns of females and juveniles were similar and diet overlap was high. Characteristics of both the fish population and their prey interact to shape patterns of resource use in fathead minnows.

Subice layering and origin of acidic waters in a small boreal lake during the spring runoff

In a small boreal forest lake, the subice circulation of waters from five distinct origins (lake premelt water, lakeshore snowpack meltwater, ice cover meltwater, groundwater and hillslope through‐flow water) was studied during the spring melt period. A network of collared access holes was used to monitor the temperature, conductivity and pH profiles of the water column beneath the ice cover. The study also included the tracing of snowbank meltwaters and through‐flow waters with rhodamine. Conductivity and pH appeared to be efficient parameters for discriminating most of the water types considered. During the spring melt three distinct low‐pH episodes were recorded at the lake outflow. The first episode (pH 5) occurred in the early melt period; snow and ice meltwaters layered beneath the ice forming a stratum ≈20 cm thick. It moved toward the outlet under laminar flow conditions (observed average velocity, 1m/h). Two subsequent pH episodes of pH 5.3 and 5.1 were observed during the massive melt period. These episodes were due to peak flows of hillslope through flow which entered the lake and formed a layer 20–40 cm thick in the water column (observed average velocity, greater than 20 m/h). The ice cover thus not only modified the nearshore water quality by inducing thermal layering but also strongly influenced the quality of the outflow waters due to the segregation and rapid evacuation of the through flow and surface meltwaters.

Influence of Environmental Factors and Piscivory in Structuring Fish Assemblages of Small Alberta Lakes

We surveyed 45 small lakes in central Alberta to determine if discrete, repeatable types of fish assemblages exist, to identify the main environmental and biotic processes likely responsible for assemblage-level patterns, and to compare and contrast Alberta patterns with those observed in other regions of North America. Overall, 11 species of fish were caught in 36 lakes; nine lakes were fishless. Hierarchical classification and detrended correspondence analysis of fish species presence/absence identified two main assemblage types, characterized by northern pike (Esox lucius) and yellow perch (Perca flavescens) versus brook stickleback (Culaea inconstans) and fathead minnow (Pimephales promelas). Pike/perch lakes were significantly deeper and larger than lakes of the stickleback/fathead assemblage type; however, a subset of the former group lacking yellow perch was environmentally similar to stickleback/fathead lakes. Piscivory by northern pike appears to be the dominant process maintaining nearly complete negative associations between members of the two assemblage types. Despite environmental and faunal-richness differences, our results were not unlike those from southern Ontario and northern Wisconsin. For small boreal lakes of North America, piscivory and processes related to a small number of environmental variables, such as maximum depth, surface area, and isolation, appear to be most important in structuring fish assemblages.

Impact of Angling on the Production and Yield of Mature Walleyes and Northern Pike in a Small Boreal Lake in Ontario

Abstract Experimental angling was conducted in 1977 on recently unexploited populations of walleye Stizostedion vitreum and northern pike Esox lucius in 364-hectare Savanne Lake, Ontario. A total effort of 450 angler-hours yielded 1.4 kg northern pike and 0.6 kg walleye per hectare. The size distribution of fish in the angling catch closely paralleled length-frequency distributions of fish in entrapment gear used during netting for spring population estimates. Although effort was low (1.24 angler-hours/hectare), angling removed 50% of the annual adult northern pike production of 2.76 kg/hectare year and 43% of the estimated annual adult walleye production of 1.38 kg/hectare year. The potential angling yield from small boreal lakes is low and, because the entire population is vulnerable to fishing, application of yield quotas and restrictions on angling effort to conserve these stocks of old, slow-growing fish is needed. It may be difficult to provide a high-quality fishing experience in such lakes.