Cape Breton Highlands National Park Research Articles

Severe environmental conditions create severe conflicts: A novel ecological pathway to extreme coyote attacks on humans

Abstract Identifying the circumstances and causes of carnivore attacks on humans is important for prevention of future incidents as well as employing effective wildlife management strategies. Cape Breton Highlands National Park (CBHNP) in Nova Scotia has experienced multiple attacks by coyotes Canis latrans on humans, including a fatal attack on an adult in 2009. Here we use a combination of data on space use and diet collected from 2011 to 2013 to reveal that limited resources and a reliance on a large ungulate (moose, Alces americanus) as the mechanism leading to aggression by coyotes in CBHNP. Resident coyotes exhibited large home range sizes (mean = 77.5 km2) indicative of limited resources and spatiotemporal avoidance of human activity. Carbon (δ13C) and nitrogen (δ15N) isotope values of sub‐sampled coyote whiskers (n = 32), which provide a longitudinal record of diet over the months before collection, revealed little intra‐ and inter‐individual variation with nearly all individuals specializing on moose, a pattern that agrees with indices of natural resource availability. Specifically, stable isotope mixing models show that moose was the most important prey for most coyotes (25/32), representing between 41% and 78% of dietary inputs. Only four coyotes exhibited use of anthropogenic resources (human foods), and only one of seven coyotes involved in attacks on people had been consuming human foods before the attacks. Synthesis and Applications: We have described a unique ecological system in which a generalist carnivore has expanded its niche to specialize on a large prey species, with the unfortunate consequence of also expanding pathways to conflicts with people. Our results suggest extreme unprovoked predatory attacks by coyotes on people are likely to be quite rare and associated with unique ecological characteristics. Extreme management actions such as bounties are unnecessary, but managers may need to employ hazing or lethal removal earlier in the conflict process than under normal circumstances. Also, users of these areas should be made aware of the risks coyotes pose and encouraged to take precautions.

The demographics of knowledge, attitudes and emotions toward coyotes

Abstract Context A coyote-caused human fatality in Cape Breton Highlands National Park of Canada (CBHNPC) occurred in 2009. Because CBHNPC is federally protected, rangers have a limited number of management options for dealing with human–coyote conflict. The park initiated the present study to understand the publics’ acceptance of coyotes. Aims This article examined relationships between each of four independent variables (respondent type (resident vs visitor), sex, age, education) and each of four dependent variables (knowledge, attitude, two emotions) related to coyotes in CBHNPC. Researchers have repeatedly suggested that demographics are related to cognitions and emotions toward wildlife. Managers can use demographic findings to target education campaigns to specific stakeholders. Methods Survey data were obtained from (a) residents living around CBHNPC (n = 556, response rate = 70%), and (b) visitors hiking two popular trails in CBHNPC (n = 443, response rate = 60%). Key results All four independent variables were related to knowledge. Visitors were more knowledgeable about coyotes than were residents. Females were more knowledgeable than were males. Younger respondents were more knowledgeable than were older individuals. All education categories differed from each other. Findings for the attitude construct were similar. Residents held negative attitudes toward coyotes, whereas visitors were slightly positive. Males and females both held negative attitudes. The youngest age category held a positive attitude, whereas the oldest group was the most negative. Respondents with a high-school degree had a negative attitude; those with a college degree held a positive attitude. For the first emotion concept, residents were more emotional than were visitors. Males were more emotional than were females, and high-school graduates were more emotional than were college graduates. For the second emotion, there were statistical differences between residents and visitors, as well as between males and females. However, age and education were not related to this scenario. Conclusions Although there were statistical differences for 13 of 16 tests, over 80% of the effect sizes were minimal and there were interaction effects among the four demographic variables. Implications Findings highlighted complexities managers should consider when designing communication strategies aimed at influencing stakeholders’ knowledge of and attitudes and emotions toward wildlife.

Seasonal and daily shifts in behavior and resource selection: how a carnivore navigates costly landscapes

The dynamic environmental conditions in highly seasonal systems likely have a strong influence on how species use the landscape. Animals must balance seasonal and daily changes to landscape risk with the underlying resources provided by that landscape. One way to balance the seasonal and daily changes in the costs and benefits of a landscape is through behaviorally-explicit resource selection and temporal partitioning. Here, we test whether resource selection of coyotes (Canis latrans) in Cape Breton Highlands National Park, Nova Scotia, Canada is behaviorally-explicit and responsive to the daily and seasonal variation to presumed costs and benefits of moving on the landscape. We used GPS data and local convex hulls to estimate space use and Hidden Markov Models to estimate three types of movement behavior: encamped, foraging, and traveling. We then used integrated step-selection analysis to investigate behaviorally explicit resource selection across times of day (diurnal, crepuscular, and nocturnal) and season (snow-free and snow). We found that throughout the day and seasonally coyotes shifted foraging behavior and altered behavior and resource choices to avoid moving across what we could be a challenging landscape. These changes in behavior suggest that coyotes have a complex response to land cover, terrain, and linear corridors that are not only scale dependent but also vary by behavior, diel period, and season. By examining the resource selection across three axes (behavior, time of day, and season), we have a more nuanced understanding of how a predator balances the cost and benefits of a stochastic environment.

Fire Behaviour Observation in Shrublands in Nova Scotia, Canada and Assessment of Aids to Operational Fire Behaviour Prediction

Parks Canada, in collaboration with Nova Scotia Lands and Forests and Natural Resources Canada, documented shrub fire behaviour in multiple plots burned over two periods: a spring period in June 2014 and a summer period in July 2017. The study area, located within Cape Breton Highlands National Park, comprised fifteen burn units (20 m by 20 m in size). Each unit was ignited by line ignition and burned under a wide range of conditions. Pre-burn fuel characteristics were measured across the site and used to estimate pre-fire fuel load and post-fire fuel consumption. This fuel complex was similar to many flammable shrub types around the world, results show that this shrub fuel type had high elevated fuel loads (3.17 ± 0.84 kg/m2) composed of exposed live and dead stunted black spruce as well as ericaceous shrubs, mainly Kalmia angustifolia (evergreen) and Rhodora canadensis (deciduous). Data show that the dead moisture content in this fuel complex is systematically lower than expected from the traditional relationship between FFMC and moisture content in the Canadian Fire Weather Index System but was statistically correlated with Equilibrium Moisture Content. A significant inverse relationship between bulk density and fire rate of spread was observed as well as a clear seasonal effect between the spring burns and the summer burns, which is likely attributable to the increase in bulk density in the summer. Unlike most shrub research, wind and dead moisture content did not have a statistically significant association with fire spread rates. However, we believe this to be due to noise in wind data and small dataset. Rate of spread as high as 14 m/min and flame lengths over 4 m were recorded under Initial Spread Index values of 6.4 and relative humidity of 54%. A comparison with a number of well-known shrubland spread rate prediction models was made. An aid to operational fire prediction behaviour is proposed, using a fuel type from the Canadian Fire Prediction System (O-1b) and a modified estimate of fuel moisture of the elevated fuel in the fuel complex.

High reliance on a diet of Moose (<i>Alces americanus</i>) by Eastern Coyotes (<i>Canis latrans</i> var.) in Cape Breton Highlands National Park, Nova Scotia, Canada

Eastern Coyote (Canis latrans var.) scats were collected along transects in Cape Breton Highlands National Park, Nova Scotia, Canada, from May 2012 to August 2013 to determine diet. Based on 294 scats, Moose (Alces americanus) remains made up the highest percentage by volume in scats during fall, winter, and spring. During the summer, Moose remains were found in over 30% of scats (18% by volume), although fruit and berries were more commonly found. No other study has documented such high annual use of Moose. As there was no evidence that the consumed Moose were killed by Coyotes, presumably Coyotes scavenged Moose that had died of natural causes.

Identifying governance problems and solutons for forest landscape restoration in protected area landscapes

Governance challenges – including ownership, decision-making, accountability, and sharing of costs and benefits – can impede forest landscape restoration in protected area landscapes. Understanding and addressing these challenges can improve the outcomes of forest landscape restoration. We tested the utility of applying an existing framework that focuses on three actions to understand governance – mapping stakeholders, contextualising and rescaling. The framework was applied to large-scale restoration initiatives in New Caledonia’s dry forest, Canada’s Cape Breton Highlands National Park and a Community Resource Management Area in Ghana’s Western Region to identify governance challenges and solutions in forest landscape restoration implementation in different contexts. Application of the framework revealed four types of governance challenges: overlapping jurisdictions, interinstitutional relationships, tenure and property rights conflict, and stakeholder power dynamics, and five types of governance solutions: supportive national-level policies, clarifying tenure, convening structures, benefit sharing and compensation, and cultural incentives. Overall, we found that the framework helped interviewees to conceptualise governance challenges and identify ways to address them.

Attitudinal Differences Among Residents, Park Staff, and Visitors Toward Coyotes in Cape Breton Highlands National Park of Canada

We explored differences and similarities among local residents, park staff, and visitors in their (a) attitudes toward, (b) fear of, (c) perceived control over, and (d) perceived likelihood of coming into contact with coyotes. Data were collected near Cape Breton Highlands National Park of Canada, where a coyote caused a human fatality in 2009. Local residents were mailed a questionnaire (n = 578; 76%) in 2011. Park staff completed the questionnaire (n = 124) in 2011 and visitors were interviewed on trails in 2011 and 2012 (n = 375). The Potential for Conflict Index2 (PCI2) was used to examine differences among these groups. Residents held more negative attitudes, reported more fear, felt less in perceived control, and reported a higher perceived likelihood of seeing a coyote than park staff and visitors. Understanding different interest-group attitudes toward coyotes facilitates the design of specialized messages to ensure different stakeholders receive appropriate information.

The Role of Cognitions and Emotions in Human–Coyote Interactions

In this article, emotional and cognitive variables were used to explain reactions to human–coyote interactions. Anticipated emotional dispositions were hypothesized to mediate the influence of general attitude and symbolic existence beliefs toward coyotes on acceptability of killing a coyote. Residents around Cape Breton Highlands National Park in Canada were mailed a questionnaire in 2011 (n = 556; response rate = 70%). Acceptability of killing a coyote was evaluated for three situations: (a) a coyote crossed the trail, (b) a coyote approached you, and (c) a snarling coyote approached you. In all three scenarios, symbolic existence beliefs and anticipated emotional dispositions directly influenced acceptability of lethal management. Emotional dispositions also mediated the relationship between attitudes and symbolic existence beliefs on lethal management in all scenarios except for scenario 3 (snarling coyote). Acceptability of lethal control was best explained by symbolic beliefs, followed by anticipated emotional disposition.

Differences in management action acceptability for coyotes in a National Park

ABSTRACTSuccessful wildlife management often depends on public acceptance of wildlife control methods. We explored the acceptability and amount of consensus among local residents, park staff, and visitors for coyote (Canis latrans) management in Cape Breton Highlands National Park of Canada (NPC). We collected data near Cape Breton Highlands NPC, where there has been an increase in human–coyote conflict. Local residents were mailed a questionnaire (n = 578; 72% return rate) in 2011. Park staff completed the questionnaire (n = 124; 85% return rate) during 2011 and visitors were interviewed on trails and given a mail‐back questionnaire during 2011 and 2012 (n = 375; 51% return rate). The Potential for Conflict Index was used to examine differences in acceptability among the 3 groups. Acceptability of different management options was evaluated for 3 situations: 1) a coyote crossed the trail; 2) a coyote approached a person; and 3) a snarling coyote approached a person. All 3 groups tended to prefer nonlethal management options, but as the scenarios increased in threat level, lethal and more invasive options became more acceptable. Understanding which management options were more acceptable in different contexts facilitates informed decision‐making when humans and coyotes come into conflict. Contrasting public(s) views against those of managers highlighted situations whereby problems might occur. © 2015 The Wildlife Society.

The spatial and seasonal variation of nitrogen dioxide and sulfur dioxide in Cape Breton Highlands National Park, Canada, and the association with lichen abundance

Over 200,000 tourists per year visit Cape Breton Highlands National Park, Nova Scotia, Canada. The forests within the park are home to many rare epiphytic lichens, the species diversity of which has declined in some areas. The primary motivation for this study was to gain insight into the concentrations and potential local and long-range sources of air pollution, but its association with lichen species diversity was also examined. Ogawa passive diffusion samplers were used to measure nitrogen dioxide (NO2) and sulfur dioxide (SO2) in the park at 19 sites in the winter and 20 sites in the summer of 2011. An improvement in the sensitivity of the sampler analytical protocol was developed. The mean concentrations in the park of winter and summer NO2 (0.81 and 0.16 ppb) and SO2 (0.24 and 0.21 ppb) are not at levels known to be phytotoxic to lichen. The NO2 concentrations in winter were significantly (p = 0.001) higher than those in summer whilst the SO2 concentrations did not differ significantly between winter and summer (p = 0.429). Highest NO2 concentrations in both seasons were observed in the Grand Anse Valley, presumably due to the steep road, emissions from the Pleasant Bay community at the foot of the valley and the enclosed topography of this area reducing dispersion of primary emissions. The SO2 concentrations in the park tended to be greater at elevated sites than valley sites, consistent with dispersion from long-range, rather than local, sources for this pollutant. Significant predictors in a multilinear regression for an index of air purity (lichen based measure of air quality) were lichen species number (p = 0.009), forest old growth index (p = 0.001) and distance from roads (p < 0.001) (model R2 = 0.8, model p = 0.004). The study suggests that local sources of pollution (roads emissions) are adversely associated with lichen species diversity in this National Park, compared with long-range transport, and that monitoring programs such as a lichen-based ‘index of air purity’ can reveal locations where ambient air pollution, although low, is nevertheless at a level that may cause ecological detriment. The implications from this work could be applicable to national parks elsewhere.

A comparison of present-day and pre-industrial cladoceran assemblages from softwater Nova Scotia (Canada) lakes with different regional acidification histories

We compared cladoceran assemblages in modern and pre-industrial sediments from cores taken in 48 softwater lakes located in four main regions of Nova Scotia (Canada) to evaluate the impacts of acidification and other recent environmental stressors. Lakes in Kejimkujik National Park showed significant increases in Holopedium relative abundances and significant decreases in Alona and other chydorids since pre-industrial times, which appear to be related to declines in pH and calcium (Ca) concentrations caused by acidic deposition. Lakes in Bridgewater also showed a significant decrease in Alona, as well as a significant increase in macrothricid (Acantholeberis and Ophryoxus) taxa that cannot be explained by declines in pH, although declines in [Ca] have been recorded. Lakes in Yarmouth did not show any significant regional changes in major cladoceran species groups. Still, pre-industrial assemblages in these lakes significantly differed from modern assemblages, with assemblage changes being lake-specific and likely related to interactions between local and regional stressors acting on individual lakes. Finally, lakes in Cape Breton Highlands National Park, located on the taiga plateau, have received historically lower levels of sulphate deposition relative to other regions in the province, and recorded a significant decrease in Alona similar to Bridgewater lakes. The province-wide decrease in Alona across different acid deposition rates suggests that limnological changes related to climate warming may be responsible. Overall, this study shows that acidification history is an important predictor of cladoceran assemblage changes since pre-industrial times in Nova Scotia lakes, although multiple stressors result in complex Cladocera responses in some regions.

First Nest Records of the Boreal OwlAegolius funereusin Nova Scotia, Canada

A nine year search for the first nesting Boreal Owls Aegolius funereus in Nova Scotia, Canada culminated in the discovery of two nests in Cape Breton Highlands National Park of Canada in 2004. In 2005, one nest north of the Park and another nest on mainland Nova Scotia were also found. Nest start dates ranged from 20 March to 3 June over the two years; only the nest with the latest start date failed entirely, the other nests fledged two or three young each. Nests were in boreal forest, with Balsam Fir Abies balsamea and White Birch Betula papyrifera normally dominating. These findings extend the known breeding distribution of the Boreal Owl eastwards by approximately 450 km at the latitude found.

Distribution and First Records of Branchiobdellida (Annelida: Clitellata) from Crayfishes (Crustacea: Decapoda) in the Maritime Provinces of Canada

Abstract Preserved specimens of the crayfish Cambarus bartonii, Orconectes limosus, and Orconectes virilis from 27 locations in New Brunswick, and O. limosus from Freshwater Lake, Cape Breton Highlands National Park, Cape Breton Island, NS, Canada, were examined for branchiobdellidans. Three species of branchiobdellidans—Bdellodrilus illuminatus, Cambarincola fallax, and Xironogiton instabilis—were identified on C. bartonii. Only branchiobdellidan cocoons were recorded on O. limosus, and only X. instabilis was recovered from O. virilis in New Brunswick. The introduction of O. limosus and O. virilis into New Brunswick does not appear to have simultaneously introduced non-native branchiobdellidans. No branchiobdellidans were found on introduced O. limosus from Freshwater Lake, NS. This work provides the first records of branchiobdellidans occurring in the Maritime Provinces of Canada, and establishes the eastern limit for these ectosymbionts in North America. In addition, one specimen of C. bartonii was fou...

The Leiodidae (Coleoptera) of Atlantic Canada: new records, faunal composition, and zoogeography

The Leiodidae (the round fungus beetles, the small carrion beetles, and the mammal nest beetles) of Atlantic Canada (New Brunswick, Newfoundland and Labrador, Nova Scotia, and Prince Edward Island) are surveyed. Twenty five species, including Colon (Colon) politum Peck and Stephan, Colon (Myloechus) forceps Hatch, Colon (Myloechus) incisum Peck and Stephan, Colon (Myloechus) schwarzi Hatch, Hydnobius arizonensis Horn, Anogdus dissimilis Blatchley, Anogdus potens (Brown), Cyrtusa subtestacea (Gyllenhal), Leiodes puncticollis (Thompson), Leiodes rufipes (Gebler), Agathidium atronitens Fall, Agathidium depressum Fall, Agathidium difforme (LeConte), Agathidium mollinum Fall, Agathidium oniscoides Palisot de Beauvois, Agathidium pulchrum LeConte, Agathidium repentinum Horn, Agathidium rusticum Fall, Gelae parile (Fall), Anisotoma blanchardi (Horn), Anisotoma discolor (Melsheimer), Anisotoma geminata (Horn), Anisotoma globososa Hatch, and Prionochaeta opaca (Say) are newly recorded in Atlantic Canada. One of these, Hydnobius arizonensis, is newly recorded in Canada. Colon (Myloechus) hubbardi Horn is newly recorded in the Maritime Provinces. Eight species are newly recorded in New Brunswick, 29 in Nova Scotia, two on Prince Edward Island, 12 on insular Newfoundland, and five in Labrador for a total of 56 new jurisdictional records. Catops paramericanus Peck and Cook and Catops simplex Say are newly recorded from mainland Nova Scotia, and records are provided to verify the occurrence of Leiodes impersonata Brown and Leiodes punctostriata Kirby in Nova Scotia, and Leptinillus validus (Horn) in insular Newfoundland. Three species, Agathidium hatchi Wheeler, Catops americanus Hatch, and Sciodrepoides watsoni (Spence), are removed from the faunal list of New Brunswick. As a result, 66 species of Leiodidae have now been recorded from Atlantic Canada. The name Anisotoma obsoleta (Horn) is revalidated while the name Anisotoma horni Wheeler is newly designated a synonym of A. obsoleta. The regional composition and zoogeography of the Leiodidae in Atlantic Canada are examined and species are grouped in six main categories, reflecting their distribution in the region. Island faunas are examined, particularly in regard to the similarities and differences of the faunas of Cape Breton Island, insular Newfoundland, and Prince Edward Island. Lone Shieling, in Cape Breton Highlands National Park, is highlighted as an apparent biodiversity 'hot spot' for this family within the region. Finally, the saproxylic component of the fauna (19 species in the Agathiidini) is briefly discussed, particularly in regard to potentially rare species, and the importance of monitoring populations of saproxylic beetles.

Glasgow Lake: an early-warning sentinel of lake acidification in Cape Breton Highlands National Park (Nova Scotia, Canada)

In contrast to other lakes studied in Cape Breton Highlands National Park (Nova Scotia, Canada), our paleolimnological results indicated that Glasgow Lake has been impacted by acidic deposition starting in the early 1900s. Based on analysis of diatom assemblages, the lake experienced a decrease in diatom-inferred lakewater pH from a pre-industrial pH of ~5.8 to a current pH of 5.3 (2000–2002 measured mean pH = 5.0) as well as a decrease in diatom-inferred Gran-alkalinity. In this study, diatom-based paleolimnological techniques were used in conjunction with a dynamic biogeochemical model (MAGIC) to assess both the timing and extent of the acidification trend, as well as determine a probable explanation as to why this lake, and none of the other 15 Cape Breton Highlands lakes studied for paleolimnology thus far, acidified under a peak non-marine sulphate deposition load of 43.6 mmolc m−2 year−1 in the mid-1970s. Steady-state models estimate that Glasgow Lake had the lowest buffering capacity of six study lakes and estimated critical sulphate loading of <1 mmolc m−2 year−1. MAGIC also estimated a loss of charge balance alkalinity from a pre-1850 value of 38 μmolc l−1 to a low of 12 μmolc l−1. While no evidence of biological recovery has been recorded, MAGIC estimates an increase in charge balance alkalinity to 27 μmolc l−1 in 2002 in response to decreased SO2 emissions. Of the five other lakes that were modelled, all showed trends towards more acidic states and subsequent increases in charge balance alkalinity; however, the empirical paleo-diatom approach applied to these lakes showed no evidence of acidification. Thus, Glasgow Lake has the lowest buffering capacity among the Cape Breton Highland study lakes and serves as a sentinel of potential acidification trends and recovery in this region.

Tracking water quality changes related to human activities in Cape Breton Highlands National Park (Nova Scotia, Canada) using paleolimnological techniques

Tracking water quality changes related to human activities in Cape Breton Highlands National Park (Nova Scotia, Canada) using paleolimnological techniques

Thin-Skinned Debris Flows in Cape Breton Highlands National Park, Nova Scotia, Canada

Landslides are common in Nova Scotia, particularly within the highly incised river valleys of the Cape Breton Highlands National Park. They have resulted in the modification of habitat and may pose considerable risk as both industrial and recreational use of this area intensifies. Field research focused on the investigation of debris flows that occur on the sides of incised river valleys where colluvium and till overlie grus, saprolite, and bedrock. The debris flows are complex events, which begin as thin translational slides or slumps and quickly evolve into debris flows. They are long and consistently narrow (&lt; 20 m), commonly initiate just below the intersection of the valley wall and the Cape Breton Highlands peneplain, fail on slopes ranging from 27° to 48°, and denude no more than 1.5 m of the surface. Failed slopes are commonly unvegetated, with no observed association with large-scale surface depressions or gullies. Two common stratigraphic relationships on failed slopes are: 1) highly compacted, impermeable clay-rich lodgement&#x0D; till overlain by highly permeable colluvium and 2) impermeable weathered bedrock in the form of saprolite overlain by permeable colluvium. Both contact boundaries act as slip surfaces. Ground water accumulates at the colluvium/till interface within the activation zone producing an effective glide plane for initial translational movement. No specific triggering mechanisms were identified, though failure is likely associated with saturation and loading due to rainfall events and spring snowmelt; root decay and loss of soil strength associated with tree root failure from spruce budworm (Choristoneura fumiferana Clem.) infestation may also be of importance.&#x0D; &#x0D; RÉSUMÉ&#x0D; &#x0D; Les glissements de terrain sont courants en Nouvelle-Écosse, en particulier à l’intérieur des vallées fluviales fortement encaissées du parc national des Hautes-Terres-du-Cap-Breton. Ils ont entraîné la modification de l’habitat et pourraient poser un risque considérable au fur et à mesure que s’intensifie l’utilisation industrielle et récréative de cette région. Des recherches sur le terrain se sont attardées sur l’étude des coulées de débris présentes sur les versants des vallées fluviales encaissées où le colluvion et le till recouvrent la groise, le saprolite et le substrat rocheux. Les coulées de débris constituent des phénomènes complexes, qui commencent sous forme d’effondrements ou de glissements plans minces et qui évoluent rapidement en coulées de débris. Elles s’étendent en longueur et demeurent constamment étroites (&lt; 20 mètres); elles apparaissent en général immédiatement en aval du point de rencontre de la paroi de la vallée et de la pénéplaine des hautes-terres du cap Breton; elles occasionnent des affaissements des pentes variant entre 27 et 48 degrés; et elles découvrent au maximum 1,5 mètre de la surface. Les versants affaissés sont communément dépourvus de végétation et on n’y observe aucune association avec des dépressions de surface ni des ravines à grande échelle. Les versants affaissés présentent deux liens stratigraphiques courants : 1) un till de fond riche en argile imperméable et tassé recouvert par un colluvion fortement perméable et 2) un substrat rocheux météorisé imperméable sous forme de saprolite recouvert de colluvion perméable. Les deux limites de contact représentent des surfaces de glissement. L’eau souterraine s’accumule dans la zone de contact du colluvion et du till à l’intérieur de la zone d’activation, produisant un plan glissant efficace pour le mouvement de translation initial. Aucun mécanisme de déclenchement particulier n’a été décelé, même si l’affaissement est probablement associé à une saturation et à un apport dû aux épisodes pluvieux et à la fonte des neiges du printemps; la pourriture des racines et la perte de résistance du sol associée à la rupture des racines des arbres causée par une infestation de tordeuses des bourgeons de l’épinette (Choristoneura fumiferana Clem.) pourraient également avoir une importance.&#x0D; &#x0D; [Traduit par la redaction]

Assessing pH changes since pre-industrial times in 51 low-alkalinity lakes in Nova Scotia, Canada

Diatom-based paleolimnological techniques were used to reconstruct lake acidification trends in 51 low-alkalinity Nova Scotia lakes that spanned gradients of dissolved organic carbon (DOC) concentrations and sulphate deposition. Pre-industrial, diatom-inferred pH values of these lakes were &lt;6.8, with 31 lakes having pre-industrial pH &lt; 6.0 and two lakes having pH &lt; 5.5. Lakes in Kejimkujik National Park documented the greatest pH decline (–0.4 pH unit (±0.2)) since the 19th century, whereas those in northern parts of the province (e.g., Cape Breton Highlands National Park) experienced little or no acidification, with a net mean pH decline = –0.1 pH unit (±0.2). While the sulphate deposition and diatom-inferred pH changes have not been as great as those observed in other acidified areas of northeastern North America (e.g., Adirondack region of New York or New England), Nova Scotia lakes have experienced biological changes toward more acidophilous diatom assemblages, especially in lakes with low pre-industrial pH values (currently with high DOC concentrations) located in Kejimkujik National Park, which receives the highest loading of sulphate deposition in Nova Scotia. However, the generally low pre-industrial pH values inferred for most of the study lakes suggest that many of these lakes were somewhat naturally acidic, but acidified further as a result of atmospheric deposition.

Long-term lake acidification trends in high- and low-sulphate deposition regions from Nova Scotia, Canada

Diatom-based paleolimnological techniques were used to study 14 lakes from two regions of Nova Scotia which represent regions of high and low sulphate deposition. Using decadal scale intervals, changes in diatom assemblages and diatom-inferred pH were tracked in relation to deposition of anthropogenic-sourced strong acids. Eight study lakes were located in Kejimkujik National Park in the southwestern part of the province, which receives an annual sulphate deposition (2000–2002) of ~10.5 kg ha−1 yr−1. These lakes showed significant changes in diatom assemblages with overall diatom-inferred acidification of ~0.5 pH units starting between 1925 and 1940, with the timing of acidification related to pre-industrial (or pre−1850) lakewater pH. Six study lakes were located in Cape Breton Highlands National Park, in northern Nova Scotia, a region of lower sulphate deposition. These lakes did not show any consistent trends in diatom assemblages or inferred pH values consistent with recent acidic deposition, but rather variations that may be related to climatic influences. Nova Scotia lakes that have been most impacted by acidic deposition had the lowest pre-industrial lakewater pH values and were in an area of relatively high sulphate deposition.

First Establishment of an Invasive Crayfish, Orconectes Limosus (Rafinesque, 1817) (Decapoda, Cambaridae) in Nova Scotia, Canada

No native or non-native crayfish species have been recorded in Nova Scotia, Canada. Aquatic surveys and research conducted by the Nova Scotia Museum during the past 25 years have not identified any populations of crayfish in the province. The only native species of crayfish in Maritime Canada is believed to be Cambarus bartonii (Fabricius, 1798), which, along with the non-native Orconectes limosus (Rafinesque, 1817) and Orconectes virilis (Hagen, 1870), have in the past been restricted to New Brunswick (Ganong, 1887; Crocker & Barr, 1968; McAlpine et al., 1991; McAlpine et al., 1999). The evidence presented here supports other recent information (McAlpine et al., 2007) that non-native crayfish are becoming more prevalent in the region and that this may require policy measures aimed at control. On 9 August 2005, SL observed an adult crayfish excavating a burrow on the south side of Freshwater Lake in Cape Breton Highlands National Park, Nova Scotia. Over the next three months, two shed crayfish exoskeletons were collected in the lacustrine areas of the lake. An adult crayfish was captured by SL in a shallow bay on the northeast corner of the lake on 2 September 2005. This specimen was photographed and measured (total length 81 mm). After confirming that the species was Orconectes limosus, a limited trapping program was conducted in 2006 to collect basic information about the population.