Variation in toxicity and ecological risks associated with some oil sands groundwaters.

The surface mining of oil sands deposits requires the removal of groundwater to stabilize the deposit (depressurization) and make it safe for mining. The chemistry and toxicity of deep groundwaters (from 45 to 144 m below an active mining operation) were characterized to determine if the release of groundwaters would pose a risk to a receiving aquatic environment. Concentrations of conventional chemicals such as nutrients and metals were generally below CCME chronic guidelines. Concentrations of oil sands naphthenic acids (NAs) varied depending on the method of measurement and were routinely >1 mg L-1. Groundwaters rarely caused lethality to fish and invertebrates in standard acute and chronic toxicity tests. Algal cell production was negatively correlated with chlorides and potentially negatively with NAs. Other chronic toxicity variations were less obviously correlated with measured chemistry. The groundwaters had moderately-high oxygen demand (2 to 33 mg L-1), likely associated with nutrients and organic substances, and thus have the potential to enrich receiving surface water environments if left untreated and depending on the receiving environment. This paper presents for the first time a comprehensive (3 year) pairing of water chemistry and toxicity data on groundwaters collected from aquifer depressurization wells below an active oil sands operation. These data will contribute to a better understanding of the environmental risk these waters potentially pose, and ultimately, to the improvement of water management strategies and the reduction of the overall surface mining footprint of oil sands operations.

Behaviour and locomotor activity of a migratory catostomid during fishway passage.

Fishways have been developed to restore longitudinal connectivity in rivers. Despite their potential for aiding fish passage, fishways may represent a source of significant energetic expenditure for fish as they are highly turbulent environments. Nonetheless, our understanding of the physiological mechanisms underpinning fishway passage of fish is still limited. We examined swimming behaviour and activity of silver redhorse (Moxostoma anisurum) during its upriver spawning migration in a vertical slot fishway. We used an accelerometer-derived instantaneous activity metric (overall dynamic body acceleration) to estimate location-specific swimming activity. Silver redhorse demonstrated progressive increases in activity during upstream fishway passage. Moreover, location-specific passage duration decreased with an increasing number of passage attempts. Turning basins and the most upstream basin were found to delay fish passage. No relationship was found between basin-specific passage duration and activity and the respective values from previous basins. The results demonstrate that successful fishway passage requires periods of high activity. The resultant energetic expenditure may affect fitness, foraging behaviour and increase susceptibility to predation, compromising population sustainability. This study highlights the need to understand the physiological mechanisms underpinning fishway passage to improve future designs and interpretation of biological evaluations.

Comparative physiology and relative swimming performance of three redhorse (Moxostoma spp.) species: associations with fishway passage success.

Our understanding of biological criteria to inform fish passage design is limited, partially due to the lack of understanding of biological motivators, cues, and constraints, as well as a lack of biological performance evaluations of structures once they are built. The Vianney-Legendre vertical slot fishway on the Richelieu River, Quebec, Canada, passes large numbers of migrating redhorse (Moxostoma spp.) upriver to spawning grounds each year. We evaluated the physiological capacity and relative swimming ability of three redhorse species (Moxostoma anisurum, Moxostoma carinatum, Moxostoma macrolepidotum; silver, river, and shorthead redhorse, respectively) to determine how these biotic factors relate to variation in fishway passage success and duration. Shorthead redhorse had higher maximum metabolic rates and were faster swimmers than silver and river redhorse at their species-specific peak migration temperatures. Blood lactate and glucose concentrations recovered more quickly for river redhorse than for silver and shorthead redhorse, and river redhorse placed second in terms of metabolic recovery and swim speed. Interestingly, fish sampled from the top of the fishway had nearly identical lactate, glucose, and pH values compared to control fish. Using passive integrated transponders in 2010 and 2012, we observed that passage success and duration were highly variable among redhorse species and were not consistent among years, suggesting that other factors such as water temperature and river flows may modulate passage success. Clearly, additional research is needed to understand how organismal performance, environmental conditions, and other factors (including abundance of conspecifics and other comigrants) interact with fishway features to dictate which fish will be successful and to inform research of future fishways. Our research suggests that there may be an opportunity for a rapid assessment approach where fish chased to exhaustion to determine maximal values of physiological disturbance are compared to fish sampled from the top of the fishway, which could reveal which species (or sizes of fish) are approaching or exceeding their physiological capacity during passage.