Christopher M Somers

University of Regina · Department of Biology

The ontogenetic development in teleost fish is sensitive to temperature, and the developmental rate has a direct relationship with the environmental temperature within a species' thermal tolerance limit. Temperature determines time to and survival at hatching. Yellow perch is a North American species of ecological and commercial importance, and its...

Anthropogenic impacts can lead to increased temperatures in freshwater environments through thermal effluent and climate change. Thermal preference of aquatic organisms can be modulated by abiotic and biotic factors including environmental temperature. Whether increased temperature during embryogenesis can lead to long-term alterations in thermal p...

The lake whitefish (Coregonus clupeaformis) is a commercially valuable freshwater species with a broad distribution in North America. Some phylogeographic work has been done on this species, but little is known about genetic population subdivision among populations of the widely dispersed Mississippian lineage. We used 3,173 single nucleotide polym...

Long-term temperature shifts associated with seasonal variability are common in temperate regions. However, these natural shifts could place significant strain on thermal stress responses of fishes when combined with mean increases in water temperatures predicted by climate change models. We examined the relationship between thermal acclimation, ba...

We examined the impact of repeated thermal stress on the heat shock response (HSR) of thermally sensitive lake whitefish (Coregonus clupeaformis) embryos. Our treatments were designed to mimic temperature fluctuations in the vicinity of industrial thermal effluents. Embryos were either maintained at control temperatures (3 oC) or exposed to a repea...

Characterizing the thermal preference of fish is important in conservation, environmental and evolutionary physiology and can be determined using a shuttle box system. Initial tank acclimation and trial lengths are important considerations in experimental design, yet systematic studies of these factors are missing. Three different behavioral assay...

We developed an incremental growth-at-temperature model to predict hatch timing for lake whitefish under varying incubation temperatures. The model extends earlier approaches by incorporating a temperature-dependence for development stage at hatching. Testing using experimentally reared embryos from Lakes Huron and Simcoe demonstrates improved pred...

Thermal preferenda are largely defined by optimal growth temperature for a species and describe the range of temperatures an organism will occupy when given a choice. Assays for thermal preferenda require at least 24 hours, which includes a long acclimation to the tank, limits throughput and thus impacts replication in the study. Three different be...

A laboratory flume was constructed to examine substrate effects on aquatic development. The flume was designed as a once‐through system with a submerged cobble‐filled corebox. Lake whitefish (Coregonus clupeaformis) embryos and temperature probes were deployed at multiple sites within the cobble and in the open water channel. Embryos were incubated...

Reduced representation (RRL) sequencing approaches (e.g., RADSeq, genotyping by sequencing) require decisions about how much to invest in genome coverage and sequencing depth, as well as choices of values for adjustable bioinformatics parameters. To empirically explore the importance of these “simple” methodological decisions, we generated two inde...

Lake whitefish (Coregonus clupeaformis) embryos incubated at low temperatures have a longer incubation period and hatch at a significantly greater size than those incubated at warmer temperatures. We examined hatch timing and morphological characteristics for whitefish embryos reared under different constant and varying temperatures to determine wh...

As urban centres expand, knowledge on the habitat and space use of native wildlife, particularly long-lived species, is required for proper management. Our objective was to understand space requirements and key habitat features necessary for long-term persistence of Western Painted Turtles (Chrysemys picta bellii) living in a Canadian urban park. U...

Pituophis catenifer sayi (Bullsnake) is a sparsely studied subspecies of conservation concern in Canada. Basic ecological information is lacking for P. c. sayi, which reaches its northern range limit in western Canada. To address this gap, we used radio-telemetry to examine space use and habitat selection in three populations of Bullsnakes in disju...

Walleye (Sander vitreus) is a popular species for catch and release angling tournaments in North America, but we currently know little about the post‐release behavior of this species and the congeneric Sauger (S. canadensis). We used radio‐ and acoustic‐telemetry to track Walleye (n = 101) and Sauger (n = 19) for seven days after release at tournam...

Understanding patterns of resource use is an important aspect of the conservation and management of animal populations. We used stable isotopes of carbon and nitrogen from nail samples of Western Painted Turtles (Chrysemys picta bellii) to examine isotopic niches for individuals in an urban population. Western Painted Turtles are omnivorous, so we...

The Great Lakes provide habitat to over 160 species of freshwater fish, many of which are ecologically and economically important. Concern for management and conservation of declining fish populations makes it important that accurate identification techniques are used for environmental monitoring programs. DNA barcoding may be an effective alternat...

Lake whitefish (Coregonus clupeaformis) utilize overwintering embryonic development (up to 180 days), and such stenothermic, cold-water embryos may be particularly susceptible to thermal shifts. We incubated whitefish embryos in temperature treatments that were constant temperature (2.0 ± 0.1 °C, 5.0 ± 0.1 °C, and 8.0 ± 0.1 °C; mean ± SD) or variab...

During incubation, round whitefish embryos may experience fluctuating or elevated temperatures from natural (e.g. seasonal temperature changes) and/or anthropogenic sources. Anthropogenic sources like once‐through cooling discharges from nuclear power plants can also expose embryos to chemicals (e.g. morpholine) and/or radiation. To examine the eff...

Barotrauma causes stress and impairment in fish and can cause mortality after catch and release. Relief of barotrauma symptoms is necessary to reduce mortality, but we currently know little about sublethal effects associated with relief methods. Here, we assess the condition and behavior of tournament-caught Walleye Sander vitreus with barotrauma b...

On the North American Great Plains, several snake species reach their northern range limit where they rely on sparsely distributed hibernacula located in major river valleys. Independent colonization histories for the river valleys and barriers to gene flow caused by the lack of suitable habitat between them may have produced genetically differenti...

Discharges from industrial cooling water systems can include low levels of morpholine (a chemical pH regulator and corrosion inhibitor), as well as transiently higher temperature effluent water which present a potential source of environmental impact to aquatic biota. The effects of environmental levels of morpholine or heat shock (HS) treatment al...

Context Many studies dichotomize habitat selection into “local” or “landscape” effects, with little explanation regarding what each represents. Ambiguous use of these terms across studies may confound observations of selection operating across different spatiotemporal resolutions and impede synthesis of scale-dependent habitat selection. Objective...

Fluctuating incubation temperatures may have significant effects on fish embryogenesis; yet most laboratory-based studies use constant temperatures. For species that experience large, natural seasonal temperature changes during embryogenesis, such as lake whitefish (Coregonus clupeaformis), seasonal temperature regimes are likely optimal for develo...

Lake whitefish (Coregonus clupeaformis) embryos were exposed to thermal stress (TS) at different developmental stages to determine when the heat shock response (HSR) can be initiated and if it is altered by exposure to repeated TS. First, embryos were subject to one of three different TS temperatures (6, 9, or 12 °C above control) at 4 points in de...

Ionizing radiation is known to effect development during early life stages. Lake whitefish (Coregonus clupeaformis) represent a unique model organism for examining such effects. The purpose of this study was to examine how ionizing radiation affects development in lake whitefish embryos and to investigate the presence of an adaptive response induce...

Round whitefish (Prosopium cylindraceum) have a broad, disjunct range across northern North America and Eurasia, and little is known about their genetic population structure. We performed genetic analyses of round whitefish from 17 sites across its range using nine microsatellites, two mitochondrial DNA (mtDNA) loci, and 4918 to 8835 single-nucleot...

Walleye Sander vitreus and sauger Sander canadensis may occupy similar niches in sympatric populations, but their long-term resource use is poorly studied. Multi-tissue (liver, muscle, and bone) isotopic niche analyses were used to compare resource use by these species in two large reservoirs in Saskatchewan, Canada. Population isotopic niches were...

Descending fish to depths of neutral buoyancy is a promising, less-invasive alternative to swim bladder venting for relieving barotrauma and reducing mortality in sport fish. However, we lack a broad perspective on the relative benefits of these two approaches. We reviewed the most up-to-date literature to evaluate the effectiveness of venting comp...

Lake Whitefish Coregonus clupeaformis is the most commercially valuable species in Lake Huron. The fishery for this species has historically been managed based on 25 management units (17 in Canada, 8 in the USA). However, congruence between the contemporary population structure of Lake Whitefish and management units is poorly understood. We used st...

Chemicals used in the prevention of corrosion and biofouling may be released into the environment via industrial cooling water discharges. We assessed the impacts of two commonly used chemicals, morpholine and sodium hypochlorite, on development in lake whitefish (Coregonus clupeaformis). Embryos were exposed chronically, beginning at fertilization...

Haskap (Lonicera caerulea L.) is a temperate fruiting shrub grown commercially in northern regions of Europe, Asia, and North America. Haskap is self-incompatible and requires insect pollinators in order to set fruit; however, very little is currently known about its floral biology or pollinator specializations, particularly in North American culti...

Lipids serve as energy sources, structural components, and signaling molecules during fish embryonic development, and utilization of lipids may vary with temperature. Embryonic energy utilization under different temperatures is an important area of research in light of the changing global climate. Therefore, we examined percent lipid content and fa...

Complete panmixia across the entire range of a species is a relatively rare phenomenon; however, this pattern may be found in species that have limited philopatry and frequent dispersal. American white pelicans (Pelecanus erythrorhyncos) provide a unique opportunity to examine the role of long-distance dispersal in facilitating gene flow in a speci...

Increasing incubation temperatures, caused by global climate change or thermal effluent from industrial processes, may influence embryonic development of fish. This study investigates the cumulative effects of increased incubation temperature and repeated heat shocks on developing Lake Whitefish (Coregonus clupeaformis) embryos. We studied the effe...

Phenotypic plasticity is the ability of an animal to modify its phenotype in response to the environment. Embryos may have critical windows during development when they are particularly plastic or susceptible to the environment. We examined whether there are critical windows during Lake whitefish ( Coregonus clupeaformis ) embryonic development whe...

Temperature has pervasive effects on poikilotherm physiology, and embryos and newly hatched/born animals are especially vulnerable to temperature shifts. Lake whitefish ( Coregonus clupeaformis ) are a North American, freshwater lake species with lengthy (80–150 day, 2–8 °C) overwintering embryonic development. Stenothermic, cold‐water embryos may...

Cross-validation results. Results of a cross-validation resampling simulation from samples of known origin. Feathers were assigned to the site with the highest number of assignments out of the 10,000 simulations. During each simulation, samples were assigned to the site with the highest probability of origin. (DOCX)

Sampling locations. Descriptive information for all sampling locations, including regional grouping, location information, sample size, and descriptive statistics for each isotope measured. (DOCX)

Fruit set in many crops is dependent on pollinating insects, but the pollination performance of floral visitors can vary tremendously among taxa. Apis mellifera L. is the primary managed pollinator used for most crops, but alternative managed bee species or wild pollinators may be more effective and efficient pollinators. In this study, we compared...

Thermal pollution from industrial processes can have negative impacts on the spawning and development of cold-water fish. Point sources of thermal effluent may need to be managed to avoid affecting discrete populations. Correspondingly, we examined fine-scale ecological and genetic population structure of two whitefish species (Coregonus clupeaform...

Details for 16 polymorphic microsatellite loci developed for lake and round whitefish specifically for this study. The size indicates the range of observed alleles in base pairs and includes the length of the CAG tag; number of individuals genotyped is N; k is number of alleles observed; Ho and He are observed and expected heterozygosity, respectiv...

Summary data for the 31 microsatellite loci used to genotype lake and round whitefish for this study. The repeat size indicates the length of the repeat within each locus; N is the number of individuals genotyped; k refers to the number of alleles observed; HO and HE are observed and expected heterozygosities, and PIC is the polymorphic information...

Thermal discharges released from industrial cooling water systems represent a potential environmental risk to fish species that spawn in nearshore waters. We investigated the impacts of in situ incubation of lake whitefish (Coregonus clupeaformis) embryos in the vicinity of a nuclear generating station. Over 3 consecutive years, fertilized embryos...

Lake (Coregonus clupeaformis) and round (Prosopium cylindraceum) whitefish are sympatric benthivores in Lake Huron that are thought to coexist via niche partitioning. However, little is known about long-term resource use and niche overlap across different temporal scales. We used a multiyear (2010–2012) and multi-tissue (liver, muscle, and bone lay...

We investigated the effects of thermal stress on embryonic (fin flutter, vitelline circulation stage) and young of the year (YOY) juvenile lake whitefish by characterizing the kinetics of the heat shock response (HSR). Lake whitefish were subjected to one of three different heat shock (HS) temperatures (3, 6, or 9°C above control) for six different...

Small mammal community composition is almost universally estimated from conventional trapping, which is logistically difficult to scale up for landscape‐level assessments. Owl pellets may be a more effective alternative for measuring small mammal community composition over large geographic areas due to the relative ease and low cost of field collec...

A reference staging series of 18 morphological stages of laboratory reared lake whitefish Coregonus clupeaformis is provided. The developmental processes of blastulation, gastrulation, neurulation as well as development of the eye, circulatory system, chromatophores and mouth are included and accompanied by detailed descriptions and live imaging. Q...

Single-molecule PCR (SM-PCR) analysis of long and repetitive DNA sequences, known as expanded simple tandem repeats (ESTRs), has been the most efficient method for studying germline mutation induction in endogenous sequences to date. However, the long length of these sequences makes mutation detection imprecise and laborious, and they have been cha...

Degraded DNA from suboptimal field sampling is common in molecular ecology. However, its impact on techniques that use restriction site associated next-generation DNA sequencing (RADSeq, GBS) is unknown. We experimentally examined the effects of in situ DNA degradation on data generation for a modified double digest RADSeq approach (3RAD). We gener...

Humans and colonial piscivorous birds are often perceived to be in conflict over shared aquatic habitats and fisheries resources in inland lakes. We examined angler perception of birds and the relative abundance of American white pelicans (Pelecanus erythrorhynchos), double-crested cormorants (Phalacrocorax auritus), western grebes (Aechmopho-rus o...

The timing, success and energetics of fish embryonic development are strongly influenced by temperature. However, it is unclear if there are developmental periods, or critical windows, when oxygen use, survival and hatchling phenotypic characteristics are particularly influenced by changes in the thermal environment. Therefore, we examined the effe...

Humans and colonial piscivorous birds are often perceived to be in conflict over shared aquatic habitats and fisheries resources in inland lakes. We examined angler perception of birds and the relative abundance of American white pelicans (Pelecanus erythrorhynchos), double-crested cormorants (Phalacrocorax auritus), western grebes (Aechmophorus oc...

Degraded DNA from suboptimal field sampling is common in molecular ecology. However, its impact on techniques that use restriction site associated next-generation DNA sequencing (RADSeq, GBS) is unknown. We experimentally examined the effects of in situ DNA degradation on data generation for a modified double-digest RADSeq approach (3RAD). We gener...

A self-contained, small-scale research hatchery was constructed in a modified chromatography refrigerator equipped with a filtered and UV-sterilized water recirculation system. Lake Whitefish Coregonus clupeaformis embryos were raised in conventional upwelling hatching jars, in dishes with a continuous slow “drip feed,” and in a variety of static w...

Shoreline development and boating on lakes of the northern Great Plains of North America have increased due to recent economic prosperity. Few studies have examined the general characteristics of habitats used by foraging water-birds and boats to determine levels of overlap. To address this issue, we conducted point count surveys of American White...

Mercury and selenium concentrations were measured in double-crested cormorants (Phalacrocorax auritus), piscivorous fish, and common prey items in five lakes in two ecoregions in Saskatchewan, Canada. Hg and Se concentrations in cormorants were within the natural ranges of birds living in un-impacted sites. Site explained a significant proportion o...

Extreme weather variation on the northern Great Plains of North America can potentially influence the abundance of grassland rodents across vast areas. We used the remains of 33,697 small mammals collected from owl pellets in central and western Canada over 15 years to determine the influence of weather on the annual abundance of deer mice (Peromys...

Little is known about the macrohabitat associations of rodents and shrews in prairie landscapes because of the logistic constraints of conventional trapping. We used the remains of 60,972 small mammals in owl pellets to assess factors affecting small mammal composition across 4.3 million hectares of the northern Great Plains of North America. Cropl...

The grasslands of southwestern Saskatchewan, Canada are home to several snake species of conservation concern at the northern extreme of their geographic range. To aid conservation assessment and management planning for these snakes, we used radio-telemetry, a geographic information system, and multivariate modeling to identify and compare macrohab...

It is clear that particulate air pollution poses a serious risk to human health; however, the underlying mechanisms are not completely understood. We investigated pulmonary transcriptional responses in mice following in-situ exposure to ambient air in a heavily industrialized urban environment. Mature C57BL/CBA male mice were caged in sheds near tw...

Historically, sperm have been seen as simply a mechanism of transferring a haploid set of chromosomes to the oocyte. However, data from assisted reproduction therapies (ART) have demonstrated that in many couples the sperm appears to be responsible for abnormal embryogenesis. Recent advances in genetic and epigenetic techniques have identified key...

Conflict between cormorants (Phalacrocorax spp.) and humans over fisheries is currently one of the most widespread wildlife management issues in the world. Cormorant impact assessments typically assume a single source of prey near the breeding colony. However, cormorants can fly long distances (>20 km), resulting in fish removal from multiple areas...

Abstract.—An overview is provided of a symposium on the direction of research and management of Double-crested Cormorants (Phalacrocorax auritus) heading into the 2000s. The current symposium built on previous efforts and described a number of focus areas of informational need, including cormorant impacts on natural resources, demographics of cormo...

Double-crested Cormorant (Phalacrocmax auritus) numbers in the Great Lakes of North America have increased dramatically during the past three decades. Current concerns include negative effects of cormorants on aquatic food webs, destruction of nesting habitat and competition with other avian species and odors due to feces. Control of cormorant nest...

Conflict between cormorants (Phalacrocorax spp.) and humans over fisheries is currently one of the most widespread wildlife management issues in the world. Cormorant impact assessments typically assume a single source of prey near the breeding colony. However, cormorants can fly long distances (>20 km), resulting in fish removal from multiple areas...