Bridging science and traditional knowledge to assess cumulative impacts of stressors on ecosystem health.

Cumulative environmental impacts driven by anthropogenic stressors lead to disproportionate effects on indigenous communities that are reliant on land and water resources. Understanding and counteracting these effects requires knowledge from multiple sources. Yet the combined use of Traditional Knowledge (TK) and Scientific Knowledge (SK) has both technical and philosophical hurdles to overcome, and suffers from inherently imbalanced power dynamics that can disfavour the very communities it intends to benefit. In this article, we present a 'two-eyed seeing' approach for co-producing and blending knowledge about ecosystem health by using an adapted Bayesian Belief Network for the Slave River and Delta region in Canada's Northwest Territories. We highlight how bridging TK and SK with a combination of field data, interview transcripts, existing models, and expert judgement can address key questions about ecosystem health when considerable uncertainty exists. SK indicators (e.g., bird counts, mercury in fish, water depth) were graded as moderate, whereas TK indicators (e.g., bird usage, fish aesthetics, changes to water flow) were graded as being poor in comparison to the past. SK indicators were predominantly spatial (i.e., comparing to other locations) while the TK indicators were predominantly temporal (i.e., comparing across time). After being populated by 16 experts (local harvesters, Elders, governmental representatives, and scientists) using both TK and SK, the model output reported low probabilities that the social-ecological system is healthy as it used to be. We argue that it is novel and important to bridge TK and SK to address the challenges of environmental change such as the cumulative impacts of multiple stressors on ecosystems and the services they provide. This study presents a critical social-ecological tool for widening the evidence-base to a more holistic understanding of the system dynamics of multiple environmental stressors in ecosystems and for developing more effective knowledge-inclusive partnerships between indigenous communities, researchers and policy decision-makers. This represents new transformational empirical insights into how wider knowledge discourses can contribute to more effective adaptive co-management governance practices and solutions for the resilience and sustainability of ecosystems in Northern Canada and other parts of the world with strong indigenous land tenure.

The use of field-based mesocosm systems to assess the effects of uranium milling effluent on fathead minnow (Pimephales promelas) reproduction.

Northern Saskatchewan, Canada is home to a uranium milling operation that discharges a complex milling effluent containing nutrients, cations and anions, and many metals including selenium (Se). Se has the potential to accumulate in a system even when water concentrations are low. This study evaluated the effects of treated uranium milling effluent and contaminated sediment in combination and in isolation to determine the contribution and importance of each source to fathead minnow (Pimephales promelas) reproduction and survival. Trios of fathead minnows were allocated to one of four treatments for 21-days where the following were evaluated; survival (adult and 5 day larval), larval deformities, reproductive effects (egg production, spawning events) and metal tissue burdens (muscle, gonad, eggs and larvae). In addition Se speciation analysis was conducted on fish tissues. Effects were solely effluent-mediated with little contribution observed due to the presence of contaminated sediments. The contaminated sediments tested were taken from the actual receiving environment and represented the sediment composition found in greatest abundance. Results showed egg production significantly increased in the effluent treatments compared to the reference water treatments. Although egg production increased following effluent exposure, there was reduced hatching and larval survival and a significant increase in skeletal deformities in 5 day old larvae. Despite these effects on the offspring, when examined in an integrated manner relative to increased egg production, the mean number of normal larvae did not differ among treatments. Total selenium significantly increased in the effluent exposed, algae, female muscle, gonad, eggs and larvae in addition to other metals. A shift in the proportion of species of selenium was evident with changing exposure conditions. Biofilm/algae was key in the transfer of available Se into the food chain from the water and a source of direct dietary exposure in fish and possibly invertebrates.

Ozonation attenuates the steroidogenic disruptive effects of sediment free oil sands process water in the H295R cell line.

There is concern regarding oil sands process water (OSPW) produced by the oil sands industry in Alberta, Canada. Little is known about the potential for OSPW, and naphthenic acids (NAs), which are the primary persistent and toxic constituents of OSPW, to affect endocrine systems. Although ozonation significantly reduces concentrations of NAs and OSPW toxicity, it was hypothesized that oxidation of OSPW might produce hydroxylated products with steroidogenic activity. Therefore, untreated and ozone treated OSPW were examined for effects on sex steroid production using the H295R Steroidogenesis Assay. Untreated OSPW significantly decreased testosterone (T) and increased 17beta-estradiol (E2) concentrations at OSPW dilutions greater or equal to 10-fold. This effect was mainly due to decreased E2 metabolism. Analysis of CYP19A (aromatase) mRNA abundance and enzyme activity suggested that induction of this enzyme activity may have also contributed to these effects. Reduction of parent NA concentrations by 24% or 85% decreased the effect of OSPW on E2 production. Although T production remained significantly reduced in cells exposed to ozone treated OSPW, the effect was diminished. Aromatase mRNA abundance and enzyme activity were significantly greater in cells exposed to ozone treated OSPW, however the magnitude was less than in cells exposed to untreated OSPW. No change of E2 metabolism was observed in cells exposed to ozone treated OSPW, which may account for recovery of E2 levels. The results indicate that OSPW exposure can decrease E2 and T production, but ozonation is an effective treatment to reduce NA concentrations in OSPW without increasing affects on steroidogenesis.

Pharmacokinetic screening of soluble epoxide hydrolase inhibitors in dogs.

Epoxyeicosatrienoic acids that have anti-hypertensive and anti-inflammatory properties are mainly metabolized by soluble epoxide hydrolase (sEH, EC 3.3.2.3). Therefore, sEH has emerged as a therapeutic target for treating various cardiovascular diseases and inflammatory pain. N,N'-Disubstituted ureas are potent sEH inhibitors in vitro. However, in vivo usage of early sEH inhibitors has been limited by their low bioavailability and poor physiochemical properties. Therefore, a group of highly potent compounds with more drug-like physiochemical properties were evaluated by monitoring their plasma profiles in dogs treated orally with sEH inhibitors. Urea compounds with an adamantyl or a 4-trifluoromethoxyphenyl group on one side and a piperidyl or a cyclohexyl ether group on the other side of the urea function showed pharmacokinetic profiles with high plasma concentrations and long half lives. In particular, the inhibitor trans-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid (t-AUCB) not only is very potent with good physiochemical properties, but also shows high oral bioavailability for doses ranging from 0.01 to 1mg/kg. This compound is also very potent against the sEH of several mammals, suggesting that t-AUCB will be an excellent tool to evaluate the biology of sEH in multiple animal models. Such compounds may also be a valuable lead for the development of veterinary therapeutics.

Individual variability in esterase activity and CYP1A levels in Chinook salmon (Oncorhynchus tshawytscha) exposed to esfenvalerate and chlorpyrifos.

Acetylcholinesterase (AChE) activity has traditionally been monitored as a biomarker of organophosphate (OP) and/or carbamate exposure. However, AChE activity may not be the most sensitive endpoint for these agrochemicals, because OPs can cause adverse physiological effects at concentrations that do not affect AChE activity. Carboxylesterases are a related family of enzymes that have higher affinity than AChE for some OPs and carbamates and may be more sensitive indicators of environmental exposure to these pesticides. In this study, carboxylesterase and AChE activity, cytochrome P4501A (CYP1A) protein levels, and mortality were measured in individual juvenile Chinook salmon (Oncorhynchus tshawytscha) following exposure to an OP (chlorpyrifos) and a pyrethroid (esfenvalerate). As expected, high doses of chlorpyrifos and esfenvalerate were acutely toxic, with nominal concentrations (100 and 1 microg/l, respectively) causing 100% mortality within 96 h. Exposure to chlorpyrifos at a high dose (7.3 microg/l), but not a low dose (1.2 microg/l), significantly inhibited AChE activity in both brain and muscle tissue (85% and 92% inhibition, respectively), while esfenvalerate exposure had no effect. In contrast, liver carboxylesterase activity was significantly inhibited at both the low and high chlorpyrifos dose exposure (56% and 79% inhibition, respectively), while esfenvalerate exposure still had little effect. The inhibition of carboxylesterase activity at levels of chlorpyrifos that did not affect AChE activity suggests that some salmon carboxylesterase isozymes may be more sensitive than AChE to inhibition by OPs. CYP1A protein levels were approximately 30% suppressed by chlorpyrifos exposure at the high dose, but esfenvalerate had no effect. Three teleost species, Chinook salmon, medaka (Oryzias latipes) and Sacramento splittail (Pogonichthys macrolepidotus), were examined for their ability to hydrolyze a series of pyrethroid surrogate substrates and in all cases hydrolysis activity was undetectable. Together these data suggest that (1) carboxylesterase activity inhibition may be a more sensitive biomarker for OP exposure than AChE activity, (2) neither AChE nor carboxylesterase activity are biomarkers for pyrethroid exposure, (3) CYP1A protein is not a sensitive marker for these agrochemicals and (4) slow hydrolysis rates may be partly responsible for acute pyrethroid toxicity in fish.