Karen A Kidd

McMaster University | McMaster · Department of Biology & School of Geography and Earth Sciences

Microplastics have been found in freshwater systems, and in turn have been detected in freshwater bivalves. However, there is limited research that defines the toxicity of bicroplastics to native freshwater bivalves that have long been imperiled in North America. Our objective was to determine whether a suite of pristine microplastics has an advers...

Managed forests contribute to both economic and non-timber values, but the ecological role of managed, including planted, forests to biodiversity objectives at the landscape scale needs to be better understood. In this project in collaboration with J.D. Irving, Limited, we: 1) used airborne LiDAR and field data to identify terrestrial habitats; 2)...

Defoliation by eastern spruce budworm is one of the most important natural disturbances in Canadian boreal and hemi‐boreal forests with annual area affected surpassing that of fire and harvest combined, and its impacts are projected to increase in frequency, severity, and range under future climate scenarios. Deciding on an active management strate...

Over a reproductive cycle, the prevalence and intensity of degeneration of testicular follicles in Megapitaria squalida collected from the mining port of Santa Rosalia (a highly metal-polluted area), and San Lucas (a less polluted site), Gulf of California, Mexico, were evaluated. At San Lucas, most individuals had a typical testicular structure; d...

Insect defoliation is a widespread cause of forest disturbance in Canada, and it has the potential to alter terrestrial carbon contributions to stream consumers and thus affect stream ecosystems. Although defoliation by spruce budworms (Choristoneura fumiferana) is considered a natural disturbance with importance to forest succession, the magnitude...

Anthropogenically modified microparticles including microplastics are present in municipal wastewater treatment plant (WWTP) effluents; however, it is unclear whether biotic exposures are elevated downstream of these outfalls. In the fall of 2019, the present study examined whether microparticle levels in resident fish, environmental samples, and c...

Pharmaceuticals and personal care products (PPCPs) occur as variable mixtures in surface waters receiving discharges of human and animal wastes. A key question identified a decade ago is how to assess the effects of long-term exposures of these PPCP mixtures on non-target organisms? Herein we review the recent progress made on assessing the aquatic...

Damming of a river can trap and elevate levels of sediment-bound elements and alter food web dynamics in created reservoirs. It follows that dams may alter how elements and other nutrients, like the beneficial omega-3 fatty acids (n-3 FAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are accumulated in fish and thus the chemical comp...

The Morone saxatilis (Striped Bass) population in Saint John River (SJR), NB, Canada, collapsed in the 1970s concurrent with dam construction, overfishing, and chemical pollution that may have impeded reproduction. To assess whether a chemical threat to Striped Bass or a health threat to fish consumers persists, we examined DDT and total mercury (T...

Unlabelled: Infaunal invertebrate communities of coastal marine sediments are often impacted by human activities, particularly in harbours and estuaries. However, while many studies have attempted to identify the key factors affecting benthic infauna, few have done so for highly energetic tidal estuaries. Samples were collected over a decade (2011...

Although various studies have reported the bioaccumulation of metals in bivalves of commercial interest from the Gulf of California (GC), the risk associated with their consumption remains poorly understood. In this study, our own and bibliographic concentrations of 14 elements in 16 species of bivalves from 23 locations were used to investigate (1...

Although macroinvertebrate communities play a key role in the cycling of nitrogen (N) and phosphorus (P) in streams, this process may be disrupted through decreased macroinvertebrate diversity or abundance from agricultural inputs of nutrients, sediments and pesticides. However, it is unclear how such community changes affect their biological stora...

Forests play a major role in maintaining healthy streams and in providing ecosystem services such as clean drinking water, flood/drought protection and biodiversity, but studies have shown that some forestry operations can compromise these benefits. To assess whether current forest management practices impact stream ecosystems, a five-year study wa...

Gut microbial communities are vital for maintaining host health, and are sensitive to diet, environment, and chemical exposures. Wastewater treatment plants (WWTPs) release effluents containing antimicrobials, pharmaceuticals, and other contaminants that may negatively affect the gut microbiome of downstream organisms. This study investigated chang...

Forest management can alter the mobilization of mercury (Hg) into headwater streams and its conversion to methylmercury (MeHg), the form that bioaccumulates in and biomagnifies through food webs. As headwater streams are important sources of organic materials and nutrients to larger systems, this connectivity may also increase MeHg in downstream bi...

The biomagnification of toxic methylmercury (MeHg) and selenium (Se) through aquatic food webs using nitrogen stable isotopes (δ¹⁵N) varies among ecosystems but underlying mechanisms are yet unexplained. Given the strong links between MeHg and thiol-containing amino acids and proteins containing selenocysteine, our hypothesis was that cysteine cont...

Fish total mercury concentration ([THg]) has been linked to various fish attributes, but the relative importance of these attributes in accounting for among-individual variation in [THg] has not been thoroughly assessed. We compared the contributions of ontogeny (age, length), growth (growth rate, body condition), and food web position (δ13C, δ15N)...

Metformin is routinely detected in aquatic ecosystems because of its widespread use as a treatment for Type 2 diabetes. Laboratory studies have shown that exposure to environmentally relevant concentrations of metformin can alter metabolic pathways and impact the growth of early life stage (ELS) fish; however, it is unknown whether these effects oc...

Microbial communities, including endosymbionts, play diverse and critical roles in host biology and reproduction, but contaminant exposure may cause an imbalance in the microbiome composition with subsequent impacts on host health. Here, we examined whether there was a significant alteration of the microbiome community within two taxa of riparian s...

Forest harvesting affects dissolved organic matter (DOM) and aqueous mercury inputs as well as the food web structure in small headwater streams, but how these upstream changes manifest downstream is unclear. To address this uncertainty, we examined DOM quality, autochthony in the caddisfly Hydropsychidae (using δ2H), and methylmercury (MeHg) conce...

Coastal lagoons are essential nursery habitats of many marine fishes, but they are often sites of intense human activities that impact water quality and potentially the fish using these habitats. We compared the variability in nutrient uptake (using δ15N and δ13C) and total mercury (THg) levels in juveniles and adults of three common species in two...

Treated effluent from municipal wastewater treatment plants (WWTPs) is a major source of contamination that can impact population size, community structure, and biodiversity of aquatic organisms. However, because the majority of field research occurs during warmer periods of the year, the impacts of wastewater effluent on aquatic communities during...

Inner Bay of Fundy Atlantic salmon (Salmo salar) are endangered anadromous fish that have the potential to provide marine-derived nutrients (MDNs) to freshwater ecosystems depending on their population abundance. Salmon have been reintroduced to the Upper Salmon River, but not to the adjacent Point Wolfe River, in Fundy National Park, New Brunswick...

Trace metals bioaccumulate in aquatic organisms and some of them biomagnify through food webs, posing a threat to the organisms or their human consumers. Although the trophodynamics of many trace metals is well known in the northern hemisphere, much less is known about metals in aquatic food webs from cold and remote coastal zones of the southern h...

The river continuum concept (RCC) predicts a downstream shift in the reliance of aquatic consumers from terrestrial to aquatic carbon sources, but this concept has rarely been assessed with longitudinal studies. Similarly, there are no studies addressing how forestry related disturbances to the structure of headwater food webs manifest (accumulate/...

Municipal wastewater treatment plants (WWTPs) contain numerous contaminants, including antimicrobials, that could affect the composition of the beneficial bacterial communities associated with host aquatic organisms. There is also potential for these effects to transfer to terrestrial predators. Riparian spiders and five families of aquatic macroin...

An increasing number of laboratory studies are showing that environmental stressors and diet affect the fish gut microbiome. However, the application of these results to wild populations is uncertain as little is known about how the gut microbiome shifts when fish are transitioned from the field to the laboratory. To assess this, intestinal content...

The Striped Bass Morone saxatilis is an apex predator that supports recreational, commercial, and First Nations traditional fisheries in the Miramichi River, New Brunswick, Canada. Historic exploitation resulted in steep population declines, forcing a complete fisheries moratorium in 2000. After 13 years of recovery, a recreational fishery was reop...

Environmental concentrations of the polycyclic aromatic hydrocarbon phenanthrene can become elevated with petroleum processing, industrial activities, and urban run-off into waterbodies. However, mechanisms related to its neurotoxicity in fish are not fully described. Here, we exposed adult fathead minnows (FHM) to an average measured concentration...

Metformin is a glucose‐lowering drug commonly found municipal wastewater effluents (MWWEs). The current study investigated the chronic effects of metformin in early‐life stages of the fathead minnow (Pimephales promelas). Endpoints assessed were growth, survival, and deformities. The larval gut microbiome was also examined using 16S rRNA gene ampli...

Long-finned pilot whales (LFPW) are cetaceans with strong social groups often involved in mass strandings worldwide. However, these beachings occur for reasons that are not fully understood. In 2016, 124 LFPW were stranded on the Chilean Patagonian islands, offering a unique opportunity to obtain crucial information on the ecology, biology, and gen...

The effects of forest harvesting on headwaters are quite well understood, yet our understanding of whether impacts accumulate or dissipate downstream is limited. To address this, we investigated whether several biotic indicators changed from smaller to larger downstream sites (n=6) within three basins that had intensive, extensive or minimal forest...

Freshwater macroinvertebrates play key ecological roles in riverine food webs, such as the transfer of nutrients to consumers and decomposition of organic matter. Although local habitat quality drives macroinvertebrate diversity and abundance, little is known about their microbiota. In most animals, the microbiota provides benefits, such as increas...

Fish mercury concentrations vary at multiple scales across the landscape due to a variety of environmental and ecological factors. We compared the relative contributions of three factors (body size, growth dilution, and food web position) to observed inter-individual and within-population variability in mercury concentrations using an extensive dat...

We studied the effects of chronic exposure to metals on energy reserves and reproduction in the clam Megapitaria squalida in two nearby populations exposed to different levels of pollution from mining operations in the Gulf of California, Mexico. Female M. squalida from San Lucas beach had good reproductive health status, whereas Santa Rosalia spec...

Municipal wastewater treatment plant (WWTP) effluents are a ubiquitous source of contamination whose impacts on fish and other aquatic organisms range across multiple levels of biological organization. Despite this, few studies have addressed the impacts of WWTP effluents on fish communities, especially during the winter—a season seldom studied. He...

Municipal wastewater treatment plant (WWTP) effluent contains pharmaceuticals and personal care products known to affect fish health and reproduction. The microbiome is a community of bacteria integral in maintaining host health and is influenced by species, diet, and environment. This study investigated changes in the diversity and composition of...

Though effects of forest harvesting on small streams are well documented, little is known about the cumulative effects in downstream systems. The hierarchical nature and longitudinal connectivity of river networks make them fundamentally cumulative, but lateral and vertical connectivity and instream processes can dissipate the downstream transport...

Leeches are widespread, found in many freshwater habitats, and have diverse dietary habits. Despite their close phylogenetic relationships to Mollusca, a phylum with species affected by exogenous estrogens, it is unclear whether Hirudinea may also be impacted. A whole‐lake experiment was done at the Experimental Lakes Area in Ontario, Canada, to as...

Fisheries in highly productive prairie lakes of Canada and the USA frequently have fish consumption advisories due to elevated mercury concentrations. This occurrence is unexpected because such alkaline lakes often exhibit lower methylmercury (MeHg) concentrations in basal trophic levels than those expected in less productive basins with circumneut...

Patagonia and Antarctica are biodiverse regions in the Southern Hemisphere, but little is known about the levels of trace elements in marine organisms from these remote coastal ecosystems. In this study, selenium (Se), copper (Cu), zinc (Zn), and stable isotopes of nitrogen (δ15N; relative trophic level) were measured in 36 marine species collected...

• Although the amino acid composition of fishes and some marine invertebrates varies among taxa and systems, similar information is lacking for freshwater invertebrates. The objectives were to characterise and compare the amino acid composition among different aquatic species, dietary habits, and environmental conditions. • Benthic macroinvertebrat...

Riparian zones contain areas of strong hydrological connectivity between land and stream, referred to as variable source areas (VSAs), and are considered biogeochemical control points. However, little is known about whether VSAs influence stream communities and whether this connectivity is affected by forest management. To address this, we used mul...

The direct effects of large-scale disturbances are readily studied because their effects are often apparent and result in large changes to ecosystems. Direct effects can cascade through the ecosystem, leading to indirect effects that are often subtle and difficult to detect. Managing anthropogenic disturbances, such as chemical contamination, requi...

A bleached kraft pulp mill discharging effluent to the Mattagami River in northern Ontario, Canada, closed after almost 90 years of operation. During its operation, effluent from the mill influenced biota in the downstream areas. To assess shifts in the reliance of biota from mill‐derived nutrients, the isotopic composition (δ13C and δ15N) of white...

Parasites can compromise the health and fitness of individual fish, and it is important to generate baseline information that can then be used to document changes in the abundance and distribution of potentially pathogenic parasites. The ectoparasitic copepod Salmincola edwardsii was assessed with respect to prevalence (percentage of infected fish...

The composition, distribution and source of 16 polycyclic aromatic hydrocarbons (PAHs) in surface sediments and tissues of the mussel Modiolus capax from three sites with increasing anthropogenic impact in La Paz Bay on the Gulf of California, were determined. Levels of total PAHs in sediments (18.9-94.5 ng/g dw) were below the effect range low for...

Historic forest management practices led to widespread aerial application of insecticides, such as dichlorodiphenyltrichloroethane (DDT), to North American conifer forests during ∼1950-1970. Lake basins thus may provide an important archive of inputs and aquatic responses to these organochlorines. We use dated sediment cores from five study lakes i...

Aquatic invertebrates vary in methylmercury (MeHg) levels among systems which has been attributed, in part, to environmental conditions, but may also be linked to differences in their biochemical composition. As MeHg is known to bind to thiol-containing amino acids such as cysteine in proteins of fish, our objective was to determine if these amino...

Although effluent from municipal wastewater treatment plants (WWTPs) is a major stressor in receiving environments, relatively few studies have addressed how its discharge affects natural fish communities. Here, we assessed fish community composition over three years along a gradient of effluent exposure from two distinct WWTPs within an Internatio...

Our understanding of how forest management practices affect the relative importance of autochthonous vs. allochthonous resource use by headwater stream food webs is relatively poor. To address this, we used stable isotope (C, N, and H) analyses of food sources and macroinvertebrates from 15 streams in New Brunswick (Canada) and assessed how differe...

Aquatic macroinvertebrate communities are often used to assess the ecological integrity of streams. However, conventional methods involving morphometric identification of macroinvertebrates are usually costly and time-consuming. Here we compare stream macroinvertebrate community metrics based on conventional morphometrics vs. non-destructive DNA me...

Methylmercury (MeHg) biomagnifies through aquatic food webs resulting in elevated concentrations in fish globally. Stable carbon and nitrogen isotopes are frequently used to determine dietary sources of MeHg and to model its biomagnification. However, given the strong links between MeHg and sulfur cycling, we investigated whether sulfur isotopes (δ...

Although octopuses are in high-demand globally and can bioaccumulate high concentrations of metals, the risk associated to its consumption is poorly understood. We compiled literature data from eight locations in Europe, North America and Northern Africa with different environmental levels of metals to evaluate: (1) the risk to human health through...

In the 12 years since Dudgeon et al. (2006) reviewed major pressures on freshwater ecosystems, the biodiversity crisis in the world's lakes, reservoirs, rivers, streams and wetlands has deepened. While lakes, reservoirs and rivers cover only 2.3% of the Earth's surface, these ecosystems host at least 9.5% of the Earth's described animal species. Fu...

Much of Canada’s industrial sector is driven by natural resources and relies heavily on provisioning services supplied by the boreal zone. However, the sometimes intensive processes used by resource-based industries and their associated infrastructure have significantly altered the region, creating concerns over the future socio-ecological health o...

We analyzed changes in the condition, early growth, and resource use of lake trout (Salvelinus namaycush) from a Boreal Shield lake in response to an experimental aquaculture operation. Annual small-scale commercial production of rainbow trout (Oncorhynchus mykiss) resulted in increased lake trout body condition during aquaculture operations, which...

European Union Directive 2013/39/EU, which amended and updated the Water Framework Directive (WFD; 2000/60/EC) and its Daughter Directive (2008/105/EC), sets Environmental Quality Standards for biota (EQSbiota) for a number of bioaccumulative chemicals. These chemicals pose a threat to both aquatic wildlife and human health via the consumption of c...

Thiol amino acids in proteins store metals like mercury, but established methods for their quantitation in freshwater species have had limited application and evaluation. As such, literature on the amino acid composition of aquatic species often lacks the thiols cysteine and methionine. Here, we evaluated a performic acid (PFA) oxidation method to...

Mercury (Hg) concentrations in aquatic biota, including fish and shellfish, were measured over the period 2006 – 2012 in the lower Penobscot River and upper estuary (Maine, USA). The Penobscot is a system contaminated with Hg by a chlor-alkali plant that operated from 1967 to 2000, discharging 6 – 12 tons of mercury into the river. Mercury levels i...