Changes in migratory fish communities and their health, hydrology, and water chemistry in rivers of the Athabasca oil sands region: a review of historical and current data

Abstract

Abstract:The long-lived migratory fish in the lower Athabasca region (including the Athabasca oil sands region) are valued ecosystem components and good bio-indicators of changes in habitat condition, water quality and quantity over the entire stream network. Changes in this region may have been caused by a variety of human activities including oil sands development, forestry, urban development, and recreational activities. We reviewed existing data to examine whether community composition and health of migratory fish (such as northern pike, walleye, and suckers) in the lower Athabasca region have changed over the past 40 years and whether these could be explained by changes in hydrology or water chemistry. Declines of 53%-100% in the abundance of three migratory fish species were detected in the Muskeg watershed (15% land change). Significant changes in fish health were detected. The largest decreases in body condition of fish in the region occurred in the late 1990s and coincided with elevated levels of fin erosion, the most frequently occurring external abnormality, and with extreme discharge conditions. Fish habitat can be affected by both increases and decreases in discharge, and the most pronounced changes were increases in some watersheds of up to 20% of average discharge post-development. In contrast, decreases in discharge post-development in the Muskeg and Steepbank rivers correlated with a decrease in precipitation. Our results show that climatic events and landscape features such as wetlands are important for understanding changes in the system. Further research is needed to examine potential ecological consequences of the observed changes in hydrology for fish and to explore what caused the changes in migratory fish communities and fish health. This will require a better understanding of the trophic structure of the system and a better monitoring program for migratory fish.Key words: biodiversity decline, land use changes, cumulative effects, long-term monitoring protocol, climate change, network scale, Alberta, Athabasca River. Résumé :Les poissons migrateurs à longue durée de vie dans la région inférieure de l'Athabasca (incluant la région des sables bitumineux de l'Athabasca) constituent des écosystèmes de valeur et de bons bio-indicateurs des changements des conditions d'habitat, soit la qualité et la quantité de l'eau sur l'ensemble du réseau de rivières. Les changements survenus dans cette région ont pu être causés par une variété d'activités humaines incluant le développement des sables bitumineux, la foresterie, le développement urbain et les activités de récréation. Les auteurs ont passé en revue les données existantes pour examiner si la composition de la communauté et la santé des poissons migrateurs (p. ex. brochet du nord, doré, meunier) dans la région inférieure de l'Athabasca ont changé au cours des 40 dernières années et si elles peuvent s'expliquer par des changements de l'hydrologie et de la chimie de l'eau. On a observé des déclins de 53 à 100 % dans l'abondance de ces trois espèc...

Increased size and relative abundance of migratory fishes observed near the Athabasca oil sands

“…In contrast to mountain whitefish, longnose sucker, and Arctic grayling, the declines in white sucker reversed in 2009. In that year, the largest recorded upstream migration of white sucker into the Muskeg River was observed (RAMP 2010;Schwalb et al 2015). These findings suggest heterogenous and complex dynamics among fish populations utilizing the Athabasca River and its tributaries near the oil sands mines.…”

“…The declines first appeared between 1977 and 1995, but also persisted until 2009, the most recently reported data from a fish fence in the Muskeg River (Schwalb et al 2015). In contrast to chemical exposure, these changes were attributed to altered hydrology and increased landscape disturbance (Schwalb et al 2015), another concern in the oil sands region. Although the declines in these three species were clear when compared with the data from 1976/1977, until 2006 they were also accompanied by reduced abundance of white sucker (Catostomus commersoni).…”

“…Documenting change in field studies using reproductive physiology in adults may, in many cases, be simpler than acute toxicity to early life stages of fish, but the consequences of either may emerge over time as reduced abundance of fish captured during field surveys (Gibbons and Munkittrick 1994). Although documenting declines in relative abundance may be rare in the oil sands region, some work has shown this response in some species (RAMP 2010;Schwalb et al 2015). Declines in abundance of three migratory species, mountain whitefish (Prosopium williamsoni), longnose sucker (Catostomus catostomus), and Arctic grayling (Thymallus arcticus) were documented using data from a series of fish fences in the Muskeg River (RAMP 2010;Schwalb et al 2015).…”

“…Although documenting declines in relative abundance may be rare in the oil sands region, some work has shown this response in some species (RAMP 2010;Schwalb et al 2015). Declines in abundance of three migratory species, mountain whitefish (Prosopium williamsoni), longnose sucker (Catostomus catostomus), and Arctic grayling (Thymallus arcticus) were documented using data from a series of fish fences in the Muskeg River (RAMP 2010;Schwalb et al 2015). The declines first appeared between 1977 and 1995, but also persisted until 2009, the most recently reported data from a fish fence in the Muskeg River (Schwalb et al 2015).…”

“…Declines in abundance of three migratory species, mountain whitefish (Prosopium williamsoni), longnose sucker (Catostomus catostomus), and Arctic grayling (Thymallus arcticus) were documented using data from a series of fish fences in the Muskeg River (RAMP 2010;Schwalb et al 2015). The declines first appeared between 1977 and 1995, but also persisted until 2009, the most recently reported data from a fish fence in the Muskeg River (Schwalb et al 2015). In contrast to chemical exposure, these changes were attributed to altered hydrology and increased landscape disturbance (Schwalb et al 2015), another concern in the oil sands region.…”