Water Air Soil Pollut (2014) 225:2211 DOI 10.1007/s11270-014-2211-7
Community Composition of Lake Zooplankton, Benthic Macroinvertebrates and Forage Fish Across a pH Gradient in Kejimkujik National Park, Nova Scotia, Canada Michelle F. Bowman & Christina Nussbaumer & Neil M. Burgess
Received: 16 July 2014 / Accepted: 31 October 2014 # Springer International Publishing Switzerland 2014
Abstract The composition of zooplankton, benthic macroinvertebrate (BMI) and forage fish communities of 20 lakes in and near Kejimkujik National Park and National Historic Site were evaluated as part of Environment Canada’s Acid Rain Biomonitoring Program. The pH of study lakes ranged from 4.3 to 6.6. Lake pH was positively correlated with alkalinity, calcium and magnesium concentrations and negatively correlated with colour, aluminium, total organic carbon and nitrogen. Gradients in overall BMI community composition and total BMI richness were strongly related to the gradient in pH, but the composition of zooplankton and forage fish communities were more strongly related to other environmental parameters such as elevation. Potential indicator species for future acid rain monitoring included Daphnia catawba, the amphipod Hyalella azteca, pill/pea clams Pisidium casertanum and Pisidium ferrugineum and larval water scavenger beetle Berosus. These chemical and biological data provide a baseline for future evaluation of the continued effects of anthropogenic deposition to this acid-sensitive region of Atlantic Canada. M. F. Bowman (*) Forensecology, Guelph, Ontario, Canada e-mail:
[email protected] C. Nussbaumer Ecotoxicology and Wildlife Health Division, Environment Canada, Dartmouth, Nova Scotia, Canada N. M. Burgess Ecotoxicology and Wildlife Health Division, Environment Canada, Mt. Pearl Newfoundland and Labrador, Canada
Keywords pH gradient . Community composition . Biological indicators . Kejimkujik National Park
1 Introduction The chemistry and biology of aquatic ecosystems in eastern and southwestern Nova Scotia continue to be significantly affected by acid deposition despite being the most naturally acidic and having some of the lowest anthropogenic deposition rates on the continent (e.g. Clair et al. 2011; Ginn et al. 2007; Jeffries et al. 2003). The natural acidity is a result of poorly buffered soils and bedrock in the region in general (e.g. Clair et al. 2011), as well as additional organic acidity from wetlands in a subset of watersheds (e.g. Clair et al. 2007; Kerekes et al. 1986). Studies of seasonal water chemistry (e.g. Kerekes et al. 1986) and paleolimnological reconstruction (e.g. Ginn et al. 2007) have shown that although the ecosystems are naturally acidic, they have acidified further as a result of anthropogenic acid deposition. Further, despite a significant reduction in longrange anthropogenic acid deposition to the region, there has been no recovery in the pH of the aquatic ecosystems, mainly due to the depletion of weathered base cations in drainage basin soils (e.g. Jeffries et al. 2003; Clair et al. 2007, 2011). Biological consequences of anthropogenic acid deposition in southwestern Nova Scotia have been documented in various aquatic trophic levels. Paleolimnological studies suggest pre-industrial diatom assemblages in lakes of Kejimkujik National Park were
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less acidophilous than current assemblages (e.g. Ginn et al. 2007). A positive relationship between pH and taxa richness has been shown for aquatic plants (Catling et al. 1986), benthic macroinvertebrates (Schell and Kerekes 1989) and fish (Watt et al. 2000) in the region. Elevated mercury levels are associated with lower lake pH in Kejimkujik lakewater (e.g. Rencz et al. 2003; Vaidya and Howell 2002), invertebrates, fish (e.g. Drysdale et al. 2005; Wyn et al. 2009, 2010) and common loons (Gavia immer, e.g. Burgess and Hobson 2006) and have been associated with impaired health of yellow perch (Perca flavescens, e.g. Batchelar et al. 2013a, b) and reduced productivity of common loons (e.g. Burgess and Meyer 2008). The pH of the rivers along the southern shore of Nova Scotia varies near the threshold toxic to juvenile salmon and has resulted in salmon runs in most rivers becoming impacted or eliminated (Watt et al. 2000). The acid-sensitive biogeochemistry of eastern and southwestern Nova Scotia are unique to North America and Europe (Elder and Martin 1989), and the associated effects on aquatic biodiversity are poorly understood; therefore, the Acid Rain Biomonitoring Program, administered by Environment Canada (McNicol et al. 1995), was expanded to include Kejimkujik National Park in 2009 and 2010. Zooplankton, benthic macroinvertebrates and forage fish were sampled from 20 lakes in the park with a pH range of 4.3 to 6.6 (Nussbaumer et al. 2014, this study). Nussbaumer et al. (2014) described the positive correlations between lake pH and the abundance of cyclopoids, bivalves, gastropods and leeches as well as other significant relationships among taxa groups and chemical parameters of interest. The goal of our study was to analyse the physical, chemical and biological data using (1) multivariate ordination, (2) biological metrics and (3) indicator species approaches to further identify biological indicators of acid stress in the region.
2 Materials and Methods Study lakes were selected to span the range of biogeochemical conditions in south western Nova Scotia and were sampled using methods developed by Environment Canada. Nussbaumer et al. (2014) provide more detailed information about the study sites and sampling methods as well as water chemistry, zooplankton and benthic macroinvertebrate (BMI) datasets.
Water Air Soil Pollut (2014) 225:2211
The lakes were located within or near Kejimkujik National Park and National Historic Site, a protected area of 404 km2 located in southwestern Nova Scotia. Eight of the lakes were sampled in June 2009 (Beaverskin, Big Dam East, George, Grafton, North Cranberry, Pebbleloggitch, Peskawa and Puzzle) and the remaining 12 lakes were sampled in June 2010 (Back, Ben, Big Dam West, Big Red, Donnellan, Frozen Ocean, Menchan, McGinty, Peskowesk, Snake, Turtle and Upper Silver). Lake chemistry data were from an Environment Canada lake monitoring network (Clair et al. 2011). Surface water samples were collected from a depth of 0.5 m at the centre of each lake during the spring and fall turnover periods each year (usually May and October) by helicopter. Analytical methods for water quality parameters are explained in Nussbaumer et al. (2014) and Eaton et al. (2012). Physical data for lakes and watersheds were drawn from Ehrman et al. (1993). Biota were collected in mid-June using protocols developed for the Environment Canada Acid Rain Biomonitoring Program in Ontario and Quebec (McNicol et al. 1995). Zooplankton were collected using a single vertical haul from 1 m above the sediment to the surface at the deepest location using an 80-μm mesh, 26cm diameter, non-metered net; five lakes were too shallow (≤2 m) to sample. Benthic macroinvertebrates were collected using 10 benthic drag or kick-and-sweep samples (0.85-mm mesh, 0.14 m2,
