Zooplankton communities are good indicators of potential impacts of Athabasca oil sands operations on downwind boreal lakes

Abstract

We used zooplankton communities as indicators to evaluate the potential influence of acidifying-eutrophying emissions from the Athabasca oil sands region (AOSR) on 244 downwind lakes in northwest Saskatchewan. The impacts of regional environmental change on zooplankton communities are determined by responses of resident species to altered local environmental conditions as well as changes in composition due to dispersal processes. To test and quantify the relative importance of these individual processes, we conducted ordination analyses, spatial modeling, and variation partitioning. Local environmental factors were the dominant determinants of community structure, including two major environmental gradients susceptible to atmospheric emissions (i.e., acid-base status and productivity). Spatial structuring of these factors induced similar spatial structures in zooplankton distribution across the region. However, disentangling any impacts of the AOSR on these environment-spatial-species relationships from the underlying natural variability was precluded by unavailability of baseline data. Nevertheless, as our findings indicate that dispersal of zooplankton was not strongly limiting across this broad geographic region, zooplankton indicators can be crucial to detect future environmental changes in lakes across northwest Saskatchewan.Résumé : Nous avons utilisé les communautés de zooplancton comme indicateurs pour évaluer l'influence potentielle des émissions acidifiantes-eutrophisantes issues de la région des sables bitumineux de l'Athabasca (RSBA) sur 244 lacs du nord-ouest de la Saskatchewan situés en aval du vent. Les impacts des modifications régionales de l'environnement sur les communautés de zooplancton sont déterminés par les réactions des espèces résidentes à la modification des conditions ambiantes locales, ainsi que par les modifications de la composition découlant de processus de dispersion. Pour valider et quantifier l'importance relative de ces différents processus, nous avons utilisé des analyses d'ordination, la modélisation spatiale et le partitionnement de la variation. Les facteurs environnementaux locaux étaient les principaux déterminants de la structure des communautés, notamment deux importants gradients environnementaux sensibles aux émissions atmosphériques, à savoir le statut acidobasique et la productivité. La structuration spatiale de ces facteurs induisait des structures spatiales semblables dans la répartition du zooplancton dans la région. Toutefois, étant donné l'absence de données de référence, il été impossible de distinguer les incidences de la RSBA sur ces relations environnement-emplacement-espèces de la variabilité naturelle sous-jacente. Cela dit, puisque nos résultats indiquent que la dispersion du zooplancton n'était par fortement limitative dans cette grande région géographique, les indicateurs zooplanctoniques peuvent jouer un rôle clé dans la détection de modifications futures de conditions ambiantes dans les lacs du nord-ouest de la Saskatchewan. [Traduit par la Rédaction]

Water chemistry, landscape, and spatial controls of δ13C and δ15N of zooplankton taxa in boreal lakes: One size does not fit all

“…Effects of spatial position alone on SI variation, i.e. independent of its effects through lake/catchmentspecific factors, can be attributable to the effects of regional-scale factors that were not explicitly measured in the present study (Anas, Scott, Cooper, & Wissel, 2014;Beisner et al, 2006). For instance, spatial variations in bedrock geology, soil properties (Shewchuk, 1982;Whitfield & Watmough, 2012) and potential atmospheric nitrogen deposition from nearby Athabasca oil sands operations (Makar et al, 2018) across the region may influence among-lake SI variability at the food-web base (Aravena, Schiff, Trumbore, Dillon, & Elgood, 1992;Elliott et al, 2007).…”

“…() and Anas et al. () for detailed descriptions of survey domain, lake selection criteria, derivation of catchment and hydromorphological attributes of study lakes, collection and processing of water and zooplankton samples, analytical procedures for water chemistry parameters, and zooplankton taxonomy. Of the 244 lakes sampled, 233 had adequate zooplankton samples for SI analysis (Figure ).…”

“…Given the likely differences in energy and nutrient fluxes through zooplankton taxa with varying dietary niches (Anas et al, 2019;Barnett, Finlay, & Beisner, 2007;Matthews & Mazumder, 2003), we hypothesised that lake/catchment-specific (CHEM + HYDR_LAND) controls of SI composition vary among zooplankton taxa with different dietary niches. Because our previous work (Anas et al, 2014;Scott, Wissel, Gibson, & Birks, 2010) indicated a limited importance of spatial factors in influencing several water chemistry variables (i.e. alkalinity, colour, DOC, and nutrient loads) and biological parameters (i.e.…”

“…chlorophyll concentration and zooplankton species composition) of the study lakes, we expected that lake/catchment-specific factors would be more important than regional factors in regulating δ 13 C and δ 15 N across all taxa. Further, given that CHEM variables (mentioned above) of the study lakes are largely influenced by HYDR_LAND attributes (Anas et al, 2014;Scott et al, 2010), we hypothesised that, of the variation explained by lake/catchment-specific factors in all taxa, a major fraction is shared by effects of CHEM and HYDR_LAND.…”

Quantifying the relative importance of natural variables, human disturbance and spatial processes in ecological status indicators of boreal lakes

“…aquatic plants disperse via wind, water and waterfowl, whereas fish rely only on hydrological connections (Shurin et al, 2009;Hajek et al, 2012). Multiple taxonomic groups are increasingly used to assess status of freshwaters; however, the importance of spatial processes have only recently been taken into account in the bioassessment (Gray and Arnott, 2011;Anas et al, 2014;Gallego et al, 2014;Siqueira et al, 2014).…”