Environmental DNA detection of endangered and invasive species in Kejimkujik National Park and Historic Site

The use of environmental DNA (eDNA) allows the early detection of aquatic species at low densities (e.g. elusive and invasive species), which otherwise could be challenging to monitor using conventional techniques. Here, we assess the ability of eDNA sampling to detect the presence/absence of one species-at-risk (Blanding’s Turtle) and two invasive species (Chain Pickerel and Smallmouth Bass) in Kejimkujik National Park and National Historic site, Nova Scotia, where the aquatic system is highly acidic and rich in organic compounds. Five replicates of 1L water samples were taken per sampling site. Water filtration and eDNA extractions were performed on-site, while qPCR reactions were performed in the laboratory using species-specific assays. Samples were treated with an inhibition removal kit and analyzed pre- and post-inhibition removal. Despite the low pH and PCR inhibitors in water samples, our results showed positive eDNA detections in almost all expected positive sites (except in one site for Blanding’s Turtle). Detections of the target species were also observed at sites where their presence was previously unknown. Our study supports the advantage of eDNA to monitor species at low densities, revealing new distributions or recently invaded areas. We also demonstrate how eDNA can directly instruct management strategies in Kejimkujik.

Potential sources and processes affecting speciated atmospheric mercury at Kejimkujik National Park, Canada: comparison of receptor models and data treatment methods

Source apportionment analysis was conducted with positive matrix factorization (PMF) and principal component analysis (PCA) methods using concentrations of speciated mercury (Hg), i.e., gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particulate-bound mercury (PBM), and other air pollutants collected at Kejimkujik National Park, Nova Scotia, Canada, in 2009 and 2010. The results were largely consistent between the 2 years for both methods. The same four source factors were identified in each year using PMF method. In both years, factor photochemistry and re-emission had the largest contributions to atmospheric Hg, while the contributions of combustion emission and industrial sulfur varied slightly between the 2 years. Four components were extracted with air pollutants only in each year using PCA method. Consistencies between the results of PMF and PCA include (1) most or all PMF factors overlapped with PCA components, (2) both methods suggest strong impact of photochemistry but little association between ambient Hg and sea salt, and (3) shifting of PMF source profiles and source contributions from one year to another was echoed in PCA. Inclusion of meteorological parameters led to identification of an additional component, Hg wet deposition in PCA, while it did not affect the identification of other components. The PMF model performance was comparable in 2009 and 2010. Among the three Hg forms, the agreements between model-reproduced and observed annual mean concentrations were excellent for GEM, very good for PBM, and acceptable for GOM. However, on a daily basis, the agreement was very good for GEM but poor for GOM and PBM. Sensitivity tests suggest that increasing sample size by imputation is not effective in improving model performance, while reducing the fraction of concentrations below method detection limit, by either scaling GOM and PBM to higher concentrations or combining them to reactive mercury, is effective. Most of the data treatment options considered had little impact on the source identification or contribution.

A risk assessment for the introduction of invasive fish for Kejimkujik National Park and National Historic Site, Canada

Recent research has highlighted the need for invasive species risk assessments that consider multiple factors, such as habitat suitability and life history. With invasive species encroaching on the boundary of Kejimkujik National Park and National Historic Site (Kejimkujik), Canada, there is concern surrounding the potential ecological effects on the Park’s freshwater ecosystems. Herein we present a multifactor risk analysis for the risks of introduction of two invasive species, smallmouth bass and chain pickerel. Methods included computer-based analysis of cost–distance and habitat suitability, and a literature-based review of management techniques. Smallmouth bass were found to have a high risk of establishment and consequent ecological effects in Kejimkujik. Although chain pickerel can also negatively affect aquatic communities, their separation from the Park’s primary watershed and low dispersal ability resulted in lower levels of risk. Four recommendations were developed following a review of management techniques: (1) containment of the source population for smallmouth bass; (2) public education, outreach and communication; (3) monitoring and rapid response upon detection; and (4) collaboration with other parties. Although the present study focused on Kejimkujik, similar challenges for invasive freshwater fish assessment and mitigation exist elsewhere, and our methods may prove illustrative for researchers and managers working under similar conditions.

Potential sources and processes affecting speciated atmospheric mercury at Kejimkujik National Park, Canada

Source apportionment analysis was conducted with Positive Matrix Factorization (PMF) and Principal Component Analysis (PCA) methods using concentrations of speciated mercury (Hg), i.e., gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particulate-bound mercury (PBM), and other air pollutants collected at Kejimkujik National Park, Nova Scotia, Canada in 2009 and 2010. The results were largely consistent between the two years for both methods. The same four source factors were identified in each year using PMF method. In both years, factor Photochemistry and Re-emission had the largest contributions to atmospheric Hg, while the contributions of Combustion Emission and Industrial Sulfur varied slightly between the two years. Four components were extracted with air pollutants only in each year using PCA method. Consistency between the results of PMF and PCA include, 1) most or all PMF factors overlapped with PCA components, 2) both methods suggest strong impact of photochemistry, but little association between ambient Hg and sea salt, 3) shifting of PMF source profiles and source contributions from one year to another was echoed in PCA. Inclusion of meteorological parameters led to identification of an additional component – Hg Wet Deposition in PCA, while it did not affect the identification of other components. The PMF model performance was comparable in 2009 and 2010. Among the three Hg forms, the agreement between predicted and observed annual mean concentrations were excellent for GEM, very good for PBM and acceptable for GOM. However, on daily basis, the agreement was very good for GEM, but poor for GOM and PBM. Sensitivity tests suggest that increasing sample size by imputation is not effective in improving model performance, while reducing the fraction of concentrations below method detection limit, by either scaling GOM and PBM to higher concentrations or combining them to reactive mercury, is effective. Most of the data treatment options considered had little impact on the source identification/contribution.

Distribution and abundance of benthic macroinvertebrates and zooplankton in lakes in Kejimkujik National Park and National Historic Site of Canada, Nova Scotia

As part of the Acid Rain Biomonitoring Program at Environment Canada, we sampled aquatic biodiversity in 20 acidic lakes in 2009 and 2010 in Kejimkujik National Park and National Historic Site of Canada and vicinity in Nova Scotia. We established an inventory of current aquatic macroinvertebrate and zooplankton species composition and abundance in each of the 20 study lakes. A total of 197 macroinvertebrate taxa were identified; the number of taxa observed was positively correlated with pH across the 20 lakes. Acid-tolerant taxa, such as isopods, amphipods, trichopterans, and oligochaetes, were common and abundant, while bivalves, gastropods, and leeches were lower in abundance. The number of isopods and amphipods collected was correlated with calcium concentration; a greater proportion of isopods than amphipods were collected from lakes with low calcium and low pH. Taxa with hard, calcareous shells, such as bivalves and gastropods, were not present in lakes with low calcium and low pH, with bivalves occurring only in lakes above pH 4.9. Odonates and ephemeropterans, which were low in abundance, were associated with a wide range of acidity. Coleopteran abundance was positively correlated with concentrations of dissolved organic carbon. A total of 26 zooplankton taxa were collected, but only cyclopoid abundance was correlated with lake pH. Results presented here provide a summary of aquatic biodiversity in lakes in Kejimkujik National Park and National Historic Site and vicinity and provide a baseline for future monitoring as acid deposition continues to affect this acid-sensitive region in Atlantic Canada.