Assessing potential for recovery of biotic richness and indicator species due to changes in acidic deposition and lake pH in five areas of southeastern Canada.
Biological damage to sensitive aquatic ecosystems is among the most recognisable, deleterious effects of acidic deposition. We compiled a large spatial database of over 2000 waterbodies across southeastern Canada from various federal, provincial and academic sources. Data for zooplankton, fish, macroinvertebrate (benthos) and loon species richness and occurrence were used to construct statistical models for lakes with varying pH, dissolved organic carbon content and lake size. pH changes, as described and predicted using the Integrated Assessment Model (Lam et al., 1998; Jeffries et al., 2000), were based on the range of emission reductions set forth in the Canada/US Air Quality Agreement (AQA). The scenarios tested include 1983, 1990, 1994 and 2010 sulphate deposition levels. Biotic models were developed for five regions in southeastern Canada (Algoma, Muskoka, and Sudbury, Ontario, southcentral Quebec, and Kejimkujik, Nova Scotia) using regression tree, multiple linear regression and logistic regression analyses to make predictions about recovery after emission reductions. The analyses produced different indicator species in different regions, although some species showed consistent trends across regions. Generally, the greatest predicted recovery occurred during the final phase of emission reductions between 1994 and 2010 across all taxonomic groups and regions. The Ontario regions, on average, were predicted to recover to a greater extent than either southcentral Quebec or the Kejimkujik area of Nova Scotia. Our results reconfirm that pH 5.5-6.0 is an important threshold below which damage to aquatic biota will remain a major local and regional environmental problem. This damage to biodiversity across trophic levels will persist well into the future if no further reductions in sulphate deposition are implemented.
Fisheries and Oceans Canada, Great Lakes Laboratory for Fisheries & Aquatic Sciences, 867 Lakeshore Rd., Box 5050, Burlington, ON, Canada, L7R 4A6. dokas@dfo-mpo.gc.ca
Susan E
SE
Doka
Donald K
DK
McNicol
Mark L
ML
Mallory
Isaac
I
Wong
Charles K
CK
Minns
Norman D
ND
Yan
D015258:Acid Rain / Q000506:poisoning*; D000818:Animals; D002170:Canada; D016208:Databases, Factual; D004784:Environmental Monitoring; D005399:Fishes; D005544:Forecasting; D007448:Invertebrates; D008962:Models, Theoretical; D011157:Population Dynamics; D012044:Regression Analysis; D015048:Zooplankton
D015258:Acid Rain