Production and population dynamics of Leptodiaptomus sicilis in a mountain lake in Alberta, Canada

Leptodiaptomus sicilis (S. A. Forbes 1882) in Pyramid Lake, Alberta, Canada, has only one main generation per year. A small summer generation probably does not survive. Adults may persist for 7 to 12 months, and individual copepods may live for up to 17 months. Retardation of the development of copepodid C4 and C 5 seems to be food linked. The high percentage of survivors (up to 97%) from the first egg pulse of the main generation, and the low percentage of survivors (as low as 3%) from the second egg pulse, is likely due to the absence of cyclopoid adults and copepodids in spring, and to both cyclopoid predation and a poor food regime in summer. Production estimates by several methods gave closely comparable results. Mean daily production by L. sicilis is 0.29 mg dry weight m^-3, and the annual P/B ratio is 2.63.     

Parasites of lake sturgeon, Acipenser fulvescens (Chondrostei: Acipenseridae), from central Canada

Nineteen species of parasites were recovered from lake sturgeon, Acipenser fulvescens, from four major waterways of Central Canada; the Saskatchewan, Nelson, Winnipeg and Rainy River systems, Twelve of these are new host records. Host specific parasites, Crepidostomum auriculatum , Diclybothrium armatum , Spinitectus acipenseri and Truttaedacnitis clitellarius , forming the core parasite species, were recovered with the highest prevalence (≥70%) and were most widely distributed. Polypodium hydriforme was recovered from only stage IV sturgeon oocytes. With the exception of Pomphorhynchus bulbocolli , prevalence and intensity of endohelminth infections were not correlated with sex or age of host but the distribution of non host-specific parasites among sampling sites was determined by the type and relative abundance of food items consumed. The parasites of lake sturgeon are closely correlated to its diet and the species of parasites recovered are more similar to those of freshwater sturgeon in Eurasia than to other species of Acipenser in North America. The present parasite community of lake sturgeon appears to have been shaped by three major factors; the presence of core parasite species which predates geographic isolation, a benthic freshwater diet which has reshaped the parasite community to one comprising freshwater species and a long association with freshwater habitats which is reflected in the reproductive isolation of the lake sturgeon and lastly, the establishment of a host-specific parasite, Spinitectus acipenseri .     

Identification of microsatellite loci in lake sturgeon,Acipenser fulvescens,and their variability in green sturgeon,A. medirostris

From (CATC)_n, (GATA)_n, (AAAC)_n, and (CA)_n–enriched libraries for the lake sturgeon Acipenser fulvescens, 254 primer pairs were developed. These primer pairs resulted in the identification of 128 microsatellite loci in either A. fulvescens or A. medirostris. Polymorphic loci were identified in both sturgeon species for 48 of the primer pairs and 14 of the primer pairs amplified polymorphic loci only in A. medirostris. Most of the identified loci appear to be tetrasomic (79.1% in A. fulvescens and 64.5% in A. medirostris). These results offer estimates of the degree of diploidization in each of these species.     

Adiaspiromycosis in striped skunks in Alberta, Canada

Pulmonary adiaspiromycosis was diagnosed in seven of 25 striped skunks (Mephitis mephitis) in east-central Alberta. The infection varied from mild, where only microscopic lesions were seen, to severe, where gross lesions of grayish-white nodules were observed in the lung parenchyma. Mild lesions were restricted to the lung, while severe lesions extended to the tracheobronchial and mediastinal lymph nodes. Histologically, the lesions were characterized by a centrally located fungal spherule, surrounded by granulomatous inflammation. The morphology of the fungal spherules was consistent with that of Emmonsia crescens. By electron microscopy, the fungal cells had an outer thick fibrillar wall and an inner cytoplasm filled with large lipid vacuoles with relatively few mitochondria, ribosomes or glycogen inclusions. The absence of endosporulation and budding suggested that each fungal cell in the lung represented a separate inhaled spore. Infection was by inhalation, nevertheless adiaspores may disseminate to the regional lymph nodes.     

A review of composting as a management alternative for beef cattle feedlot manure in southern Alberta, Canada

Composting is gaining increased acceptance as a management alternative for the large volumes of manure produced by southern Alberta's beef cattle feedlots. Research on windrow composting of feedlot manure was initiated at the Lethbridge Research Centre of Agriculture and Agri-Food Canada in 1996. Early studies looked at physical and chemical changes during composting. Studies have also been conducted on greenhouse gas emissions during composting and the effect of composting on reduction of pathogens, parasites and weed seed viability. The quality of commercially-produced composts at southern Alberta feedlots has been examined as has the mineralization rates of soil-applied composts. This paper reviews results from our feedlot manure composting research program.     

Post-Hypsithermal plant disjunctions in western Alberta, Canada

Aim Evaluate the hypothesis that nine disjunct vascular plant species along the eastern slopes of the Rocky Mountains and in the Peace River District of west‐central Alberta represent remnants of more southerly vegetation that occupied these areas during the Holocene Hypsithermal (9000–6000 yr bp ). Alternatively, these plants represent populations that became established because of independent chance dispersal events. Location This study focuses on the area east of the Rocky Mountain Continental Divide in the Province of Alberta and the State of Montana in western Canada and USA, respectively. Methods Disjunct species were identified and their distributions mapped based on a review of occurrence maps and records, botanical floras and checklists, herbaria specimens, ecological and botanical studies, and field surveys of selected species. A disjunct species was defined as a plant population separated from its next nearest occurrence by a distance of > 300 km. Evaluation of the hypothesis was based on a review of published and unpublished pollen stratigraphy and palaeoecological studies. The potential geographical distribution of Hypsithermal vegetation was based on modern regional‐based ecosystem mapping and associated monthly temperature summaries as well as future climatic warming models. Results The hypothesis was compatible with Holocene pollen stratigraphy, Hypsithermal permafrost and fen occurrence, and palaeosol phytolith analyses; and future global climatic warming models. Modelled regional Hypsithermal vegetation based on a 1 °C increase in July temperatures relative to current conditions, indicated that much of the boreal forest zone in Alberta could have been grassland, which would explain the occurrence of Prairie species in the Peace River District. This amount of latitudinal vegetation shift (6.5°) was similar to an earlier Hypsithermal permafrost zone location study. An equivalent shift in vegetation along the eastern Cordillera would have placed south‐western Montana‐like vegetation and species such as Boykinia heucheriformis (Rydb.) Rosend. and Saxifraga odontoloma Piper within the northern half of the Rocky Mountains and foothills in Alberta, which represents the location of modern‐day disjunct populations of these species. Main conclusions Warmer and drier climatic conditions during the Holocene Hypsithermal resulted in the northward displacement of vegetation zones relative to their current distribution patterns. Most of Alberta was probably dominated by grasslands during this period, except the Rocky Mountains and northern highlands. Modern‐day species disjunctions within the Rocky Mountains and Peace River District as well as more northerly areas such as the Yukon Territory occurred when the vegetation receded southward in response to climatic cooling after the Hypsithermal. Wind dispersal was considered an unlikely possibility to explain the occurrence of the disjunct species, as most of the plants lack morphological adaptations for long distance transport and the prevailing winds were from west to east rather than south to north. However, consumption and transport of seeds by northward migrating birds could not be excluded as a possibility.     

Distribution of mitochondrial DNA variation in lake sturgeon (Adpenser fulvescens) from the Moose River basin, Ontario, Canada

We analysed mitochondrial DNA (mtDNA) variation of lake sturgeon ( Adpenser fulvescens ) from the Moose River basin. Our objective was to address various proximate and ultimate factors which may influence the distribution of lake sturgeon mtDNA haplotype lineages in this watershed. The lake sturgeon sampled were characterized by only two mtDNA hapiotypes based on a restriction fragment length polymorphism analysis with 40 restriction endonucleases and direct sequencing of 275 nucleotides in the mtDNA control region. We detected no heterogeneity in the mtDNA haplotype frequencies of lake sturgeon captured from different sites within rivers including those separated by major hydroelectric installations. However, lake sturgeon from one tributary had significantly different haplotype frequencies than those from other tributaries suggesting that they composed a discrete genetic stock. These results suggest that gene flow among most sites is significant and is an important factor affecting the distribution of mtDNA variation in this species. The genetic structuring and diversity are discussed in relation to lake sturgeon management and conservation.     

Herpesvirus infection in woodland caribou in Alberta, Canada

Sera and genital swabs collected from 121 adult woodland caribou (Rangifer tarandus caribou) in five subpopulations in northern Alberta, Canada, between December 1997 and October 1999, were examined for evidence of infection with herpesviruses or pestiviruses. No virus was isolated from sera or swabs, and no antibodies against bovine viral diarrhea virus were detected. However, 63 (52%) of the 121 animals had neutralizing antibody titers against bovine herpesvirus 1. There was sufficient serum from 37 of the 121 caribou to allow parallel testing for antibodies against a new alphaherpesvirus isolated from an elk (Cervus elaphus nelsoni), and 20 animals had antibodies against this virus. Paired sera collected 11 mo apart from 14 caribou showed seroconversion in seven animals, indicating that an active herpesvirus infection was present. Virus neutralization data suggest that these caribou are infected with a distinct alphaherpesvirus.     

Seasonal variation in the diet of juvenile lake sturgeon,Acipenser fulvescens,Rafinesque, 1817, in the Winnipeg River,Manitoba, Canada

The lake sturgeon, Acipenser fulvescens, is a threatened species across most of its range. To understand any potential shifts in diet across season or habitat, stomach contents were examined from juvenile lake sturgeon caught in the Winnipeg River, Manitoba, Canada. This information will aid in assessment of environmental impacts and conservation initiatives for this threatened species. From 2006 to 2008 gut contents were collected from juvenile lake sturgeon using a non‐lethal gastric lavage methodology. Juvenile lake sturgeon were sampled from four discrete deep water habitat types (13.7–27.4 m depths), during the months of May, June, July and October. In total, 13 066 prey items belonging to 14 prey groups were collected from 345 juvenile lake sturgeon (251–835 mm TL). Overall, juvenile lake sturgeon consumed a low diversity of organisms; insect larvae from three invertebrate orders, Trichoptera, Diptera and Ephemeroptera, accounted for 97.4% of the total numeric abundance of prey items recovered. A relationship between size of juvenile lake sturgeon and prey quantity or type was not observed. Diet of juvenile lake sturgeon varied in relation to season, with Diptera (77.6%) being the most abundant prey in May, Trichoptera the most abundant in June (n = 3,056, 60.4%) and July (n = 2,055, 52.6%). During October, 96% of stomachs examined were empty. In terms of habitat type, the standardized abundance of invertebrate prey items was highest in deep water habitats characterized by medium water velocity (depths > 13.7 m) and coarse substrate (particle sizes > 0.063 mm) in May and June when compared to deep water habitats characterized by low water velocity (<0.2 m.s^?1) and fine substrate (particle sizes < 0.063 mm). However, in July, the opposite was observed and prey abundance in juvenile lake sturgeon stomachs decreased with increasing particle size. Results suggest a high degree of dietary overlap among juvenile lake sturgeon from multiple size/age classes occupying deep‐water habitats of the Winnipeg River.     

The spatial and temporal distribution of an epiphytic algal community in a shallow prairie-parkland lake – Alberta, Canada

In Hastings Lake (longitudes 113°15' and 53°50'N), a shallow eutrophic lake, the spatial and temporal changes in species composition. diversitv. standing crops, and primary productivity of the epiphytic algae attached to Phragmnes australis and Scirpus validus were investigated in relation to the physico-chemical environment. Of the dominant species, cyanophycean algae ( Lyngbya diguetii and Calothrix sp.) developed best in the 25 cm region below the water surface, while the chlorophycean alga, Stigeoclonium nanum and the diatoms (Cocconeis placentula, Gomphonema parvulum and Rhoicosphenia curvata) did so in the 50 cm and 75 cm regions, respectively. Certain dominant species persisted throughout, interrupted by "shock periods" which created spring, summer, and autumn peaks. Species diversity indices increased with depth, and generally decreased spring through winter. Standing crop maxima occurred within the top 25 cm of the host stems, and showed spring and larger autumn peaks before declining to low. yet significant winter levels. Productivity, too, was greatest in the top 25 cm region, and again peaked in the spring and autumn. Cross incubation studies elucidated vertical and seasonal relationships among productivity, photosynthetic index, and efficiency, and productivity efficiency. An interplay of "sun and shade" adapted populations within the community was found. The epiphytic algae displayed but a muted seasonal response to physico-chemical fluctuations: however, there was an association with overall nutrient changes as determined by meq HCO₃⁻I⁻¹.     

Flowering plant phenology and weather in Alberta,Canada

Plant phenology can be used for biomonitoring climate change. The flowering of certain temperate zone plant species occurs in response to accumulated heat. Networks of observers presently provide data on the timing of the growth of native and crop plants to Agro-meteorological Departments in Europe and the United States. In Alberta, a phenological survey which began in 1987 records flowering times for 15 native plants, with about 200 volunteers contributing observations annually. Six years of data have been summarized and correlated with temperature measurements. The Alberta phenological data can provide a key to sound decision-making in two ways: by providing proxy data on key variables to which vegetation responds, and by providing a model for transforming simple weather data into biologically meaningful zones.     

Paleolimnology of Two Shallow Lakes in Central Alberta,Canada

An interpretation of postglacial change in water quality and productivity has been made for two shallow lakes in Central Alberta, Canada, namely Hastings Lake (longitude 113° 00′ W; latitude 53° 30′ N) and Lac Ste. Anne (longitude 114° 21′ W; latitude 53° 41′ N). Erosion rates around Lac Ste. Anne have remained constant. Similarly productivity has changed little although macrophytes contributed more to total production during the early stages. Hastings Lake has responded more sensitively to changes in the balance of precipitation and evaporation. From 5500 to 4000 year B. P. it was shallower than at present. Productivity during this early phase was less but macrophytes and allochthonous organic matter (i. e., leaf litter) probably contributed a greater proportion of the organic influx. After water levels rose productivity increased remaining steady until 2500 year B. P. when a slight decline occurred. Throughout the high water period oxygen depletion has not been serious. Any period of reducing conditions has been brief. Productivity has never been nutrient-limited. Elevation of the lake surface increased potential volume for production and reduced turbulent resuspension of bottom sediments permitting greater light penetration, and enhanced algal production. Difference between the sedimentary record of these two lakes, as well as the two basins of Hastings Lake, demonstrates the individualistic responses of basins and lakes to climatic events.     

Postfire carbon balance in boreal bogs of Alberta, Canada

Boreal peatland ecosystems occupy about 3.5 million km² of the earth's land surface and store between 250 and 455 Pg of carbon (C) as peat. While northern hemisphere boreal peatlands have functioned as net sinks for atmospheric C since the most recent deglaciation, natural and anthropogenic disturbances, and most importantly wildfire, may compromise peatland C sinks. To examine the effects of fire on local and regional C sink strength, we focused on a 12 000 km² region near Wabasca, AB, Canada, where ombrotrophic Sphagnum‐dominated bogs cover 2280 km² that burn with a fire return interval of 123±26 years. We characterized annual C accumulation along a chronosequence of 10 bog sites, spanning 1–102 years‐since‐fire (in 2002). Immediately after fire, bogs represent a net C source of 8.9±8.4 mol m⁻² yr⁻¹. At about 13 years after fire, bogs switch from net C sources to net C sinks, mainly because of recovery of the moss and shrub layers. Subsequently, black spruce biomass accumulation contributes to the net C sink, with fine root biomass accumulation peaking at 34 years after fire and aboveground biomass and coarse root accumulation peaking at 74 years after fire. The overall C sink strength peaks at 18.4 mol C m⁻² yr⁻¹ at 75 years after fire. As the tree biomass accumulation rate declines, the net C sink decreases to about 10 mol C m⁻² yr⁻¹ at 100 years‐since‐fire. We estimate that across the Wabasca study region, bogs currently represent a C sink of 14.7±5.1 Gmol yr⁻¹. A decrease in the fire return interval to 61 years with no change in air temperature would convert the region's bogs to a net C source. An increase in nonwinter air temperature of 2 °C would decrease the regional C sink to 6.8±2.3 Gmol yr⁻¹. Under scenarios of predicted climate change, the current C sink status of Alberta bogs is likely to diminish to the point where these peatlands become net sources of atmospheric CO₂‐C.     

Projected lake sturgeon recovery in the Milwaukee River,Wisconsin, USA

Using a forward projecting population model, the timing and scale of Lake Sturgeon Acipenser fulvescens (LS) recovery and natural reproduction was estimated for the Milwaukee River in Wisconsin, USA for the years 2004–2048. LS, a widely distributed potamodromous Acipenseridae species in North America, have, like other sturgeon species, suffered population declines due to overharvest and other factors since the 1800s. LS recovery efforts were initiated in the early 1980s following the successful development of LS propagation techniques and stocking has become a widely utilized tool in LS recovery programs. Sturgeon recovery programs are long-term endeavors, with annual stocking usually planned for 25 plus years, along with population assessments and habitat improvements conducted over decades before project success can be verified. LS recovery activities on the Milwaukee River, a Lake Michigan tributary in southeast Wisconsin, began with barrier mitigation in 1997 and stocking in 2003. The modest size of the Milwaukee River, along with habitat improvements, and 17 years of stocking, provided an opportunity to model and predict LS population recovery trends. A forward projecting population model with an imbedded stochastic Ricker stock-recruitment relationship, adjusted for the estimated LS productive capacity of the Milwaukee River, estimated the timing and scale of LS recovery during 2004–2048 predicting a 18.3% annual average population rate of increase during the stocking period, and a 5.7% post-stocking rate. Accelerated LS growth and maturity due to goby consumption built into the model resulted in projections of gravid adult males present in 2012 and spawning adult females and natural recruitment in 2019. During the 2020 spawning period a group of adult-sized LS were observed in the Milwaukee River below an intermittent barrier on the river. The model predicted adult LS densities to grow from 22 in 2012 to 8088 in 2048, and annual natural recruitment to grow steadily from 76 yearlings in 2019 to an average of 4000 yearlings/year during 2039-2049. The estimated number of yearling recruits per spawning (gravid) female dropped steadily from 21 in 2019 to 8 recruits per gravid female in 2048 as a function of the Ricker stock-recruitment relationship built into the model. The model results indicate that significant LS recovery can possibly begin in a shorter time frame on Great Lakes tributaries than originally expected through systematic resolution of habitat issues and LS stocking. Results can also be used to help anticipate recovery trends, fine tune stocking and habitat strategies, and plan LS recovery assessments.     

Ontogeny of light avoidance in juvenile lake sturgeon

Hatchery‐reared age 1+ and 4+ lake sturgeon (Acipenser fulvescens) were assayed to determine the effectiveness of coloured, strobing LED light guidance device (LGD) at achieving behavioural guidance for attraction or avoidance responses. Based on an initial y‐maze dichotomous choice study in age 1+ fish during daytime, we selected green, blue, orange, and full‐spectrum white light, all strobing at 1 Hz, for further testing. During nighttime light guidance trials, age 1+ sturgeon demonstrated the fastest entries and greatest proportion of entries to the cone of illumination in the experimental raceway when the LGD was producing blue light, and the lowest proportion of entries in response to orange light. Conversely, they also spent the greatest amounts of time under illumination during orange light trials. Blue light was associated with the greatest proportion and total numbers of complete passages through the illuminated zone, although passage rates through this area were observed during the unilluminated control trials. White light resulted in the least time spent in the illuminated zone, and the lowest rates of passage. Under the nighttime testing scenario, the age 4+ sturgeon, by contrast, demonstrated strong avoidance of blue light and white light. While their behaviour was negatively phototactic in general, orange light was the least repulsive. For the behavioural guidance of lake sturgeon moving at night, we recommend the use of blue light strobing at 1 Hz for the attraction of the 1+ age class and white light strobing at 1 Hz for their repulsion. For age 4+ fish, we recommend the use of blue light or white light strobing at 1 Hz for repulsion and caution that (a) light as a behavioural guidance tool appears most effective as a repulsive stimulus, and (b) further testing under both laboratory and field conditions are required.     

The lake sturgeon,Acipenser fulvescens,in the Menominee River,Wisconsin-Michigan

Synopsis The Menominee River is the boundary between the Upper Peninsula of Michigan and northeastern Wisconsin. It contains one of the few fishable lake sturgeon populations remaining in either state. Two sections of the river harbor naturally reproducing sturgeon stocks. Dams at either end of these sections curtail upstream movement of fish; however, some sturgeon move downstream over the dams. Surveys conducted in 1969 and 1970 and again in 1978 and 1979 intensively studied the sturgeons in a 42 km stretch of the river. Mark and recapture estimates of the number of sturgeon longer than 25 cm in this section ranged from 1884 to 2865. The number of fish longer than 107 cm ranged from 185 to 243. An estimate of 2834 sturgeon between 25 and 165 cm was made on a different 34 km stretch in 1979. Censuses on the hook and line fishery in 1969 and 1970 estimated sturgeon harvests of 59 and 48 fish, respectively. In 1974, the size limit was raised from 107 to 127 cm. Harvests of these larger fish were estimated at 19 and 41 in 1981 and 1982, respectively. Some other characteristics of the sturgeons and the fishery on the Menominee are also included.     

Status and management of white sturgeon in the Columbia River in British Columbia, Canada: an overview

White sturgeon ( Acipenser transmontanus ) in the Columbia River in Canada have recently been listed as Endangered/Critically Imperiled, based on a shift in size and age-class composition from a population dominated by juveniles in the early 1980s to one presently dominated by adults. This shift has been attributed to a poor survival of early life stages. To determine the causes for this poor survival, investigations conducted annually since 1990 have focussed on identifying white sturgeon movement patterns, population dynamics, reproductive biology, and critical habitats. The reasons for the low recruitment remain poorly understood but river regulation and reservoir formation due to dam construction and pollution from municipal and industrial effluent inputs are suspected as contributing factors.
The history of dam development on the Columbia River and implications to white sturgeon are discussed from a historical perspective. A synopsis of post-1990 study results is provided and discussed in the framework of management strategies that include: 1) angling regulations, 2) flow enhancement strategies during spawning, 3) development of a population stabilization plan, 4) investigations into the feasibility of artificial stock supplementation, and 5) proposed future study programs to identify factors limiting recruitment.