Mersey Tobeatic Research Institute (MTRI) : Institut de recherche du Mersey Tobeatic


MTRI is a non-profit co-operative with a mandate to promote sustainable use of natural resources and biodiversity conservation in the Southwest Nova Biosphere Reserve and beyond through research, education, and the operation of a field station.

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Backyard Biodiversity

Backyard Biodiversity

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Effects of Acid Precipitation on Lakes and Rivers

Acidification of freshwater lakes in Nova Scotia is causing concern in many aspects of its ecosystems, including Common loon productivity levels and fish composition. Kejimkujik National Park and National Historic Site and surrounding area contains poor acid buffering geology and soils. The area is topographically low in comparison to surrounding areas, receives deposition of acid rain from major emission producers in central Canada and the northeastern United States, and the area's lakes are small and shallow. This causes relatively low pH levels in the freshwater lakes of the area. Evidence shows acidity to be recovering in precipitation after a reduction in emissions, but at a slower rate than originally expected. Monitoring has been undertaken to acquire information on water quality that will lead to a model for future management plans.

By measuring pH, dissolved oxygen, temperature, and conductivity of selected lakes in and around Kejimkujik National Park and National Historic Site, we will gain an understanding of how emission reductions and climate variations affect acidity, and better understand how water quality affects ecosystems in the long term.

Water quality data is collected at meter intervals and at the deepest point in the lake using a YSI multiprobe Sonde (pH, dissolved oxygen, temperature and conductivity) and a Secchi disk (lake colouration). Water samples are collected to test concentrations of Chlorophyll a in lakes as well.

Photo Credit:  Julia Reid 



Water Quality in ACPF Habitat

Atlantic Coastal Plain Flora (ACPF) is a group of plants found along the low lying land of the Atlantic coastal plain.  These plants are typically poor competitors against other plants and therefore they often thrive in the areas where other plants are not able to grow quickly.  These are typically along lake shorelines with a high degree of winter ice scour, where flooding is common, and in areas with low water nutrient levels (oligotrophic).  Although ACPF can be found near water with moderate (mesotrophic) or even high (eutrophic) nutrient levels, increased lake nutrient levels have been identified as a significant threat to ACPF species.


Project Objectives



  • Water samples and on-site measurements of water quality data were collected at the deepest point of the lake four times annually (May, July, August and October).

  • The Carlsons trophic status index (TSI) was calculated for each sampling site. 

  • Field parameters (temperature, dissolved oxygen, turbidity, pH and salinity) were collected using a YSI Sonde.

  • Phosphorus, nitrogen and chlorophyll measurements were obtained by independent laboratory measurements.  True colour and alkalinity obtained in the fall through laboratory measurements.

  • Community members aided in water quality sample collection.

Photo Credit:  Colin Gray 


2014 Results 

  • Twelve high priority lakes with a total of 15 sites were sampled (Tusket: seven, Medway: five), four times each (May, July, August and October).

  • With data averaged over all four sampling periods in 2014, six sites were found to be oligotrophic, five mesotrophic and two eutrophic (both on the Carleton River) based on the Carlsons TSI value. 

  • On average all sites show decreased water quality when compared to baseline data collected in 2002.  


Years of Data 

  • Ongoing project since 2010



  • Government of Canada Habitat Stewardship Program for Species at Risk

  • Parks Canada

  • Mersey Tobeatic Research Institute

  • Atlantic Coastal Plain Flora Recovery Team

  • Tusket River Environmental Protection Agency

  • Acadia University

  • St. Mary’s University

  • Sage Environmental Program


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