The Bras d’Or Lakes are a unique in-land sea ecosystem and now a UNESCO Biosphere Reserve. The Lakes are affected not only by activities taking place on its waters, but also by activities upstream on the many brooks and streams that flow into it. This project was designed to assess areas of ecological vulnerability in and around the East Bay of the Bras d’Or Lakes by determining the impact of sedimentation from freshwater sources and assessing the ecological integrity of freshwater habitats flowing into the lake.
Sedimentation is the end result of erosion. Forces of erosion such as flowing water, wave action, heavy rain events, and wind, act as a vehicle that suspends and transports small sediment particles (e.g. clay, silt, and sand) until they are confronted with a barrier. Once this occurs, the suspended particles settle and become deposits; this is the natural process of sedimentation. This process is undoubtedly influenced by human land use practices and aquatic habitat alteration. Since the Bras d’Or Lakes are a primarily closed system with numerous freshwater inputs, our activities around this watershed are almost certainly having an effect on sedimentation. Excessive sedimentation is associated with habitat degradation for both aquatic flora and fauna.
The health of freshwater habitat will be assessed by examining its inhabitants and connectivity. Canadian Aquatic Biomonitoring Network (CABIN) protocol was used to enhance our understanding of the quality and health of these habitats by assessing invertebrate assemblages, water parameters, and physical characteristics of the stream environment. Connectivity of streams flowing into the Bras d’Or was investigated through culvert assessments, since these structures play a vital role in providing passage for fish and affect sediment transport. Sedimentation, faunal composition, and aquatic connectivity are interconnected, and examining all three leads to a comprehensive, ecosystem approach for understanding the impacts of freshwater input on the Bras d’Or Lakes.
The objectives of this project were:
Objective 1. Characterize and monitor sedimentation at the outflow of five brooks in East Bay. This was accomplished through direct sampling of offshore sediment and collecting characterizing parameters of streams suspected to be transporting sediment.
Objective 2. Determine the ecological integrity of stream habitats flowing into East Bay by assessing stream health and connectivity. Habitat quality was assessed using CABIN protocol and connectivity was measured using culvert assessments.
Five brooks with outflows into the East Bay of the Bras d’Or Lakes were selected for study: Breac Brook, MacIntyres Brook, McNeils Brook, Irish Cove Brook, and Campbells Brook. Stream characteristics pertaining to water quality (dissolved oxygen, temperature, conductivity, turbidity, and pH) were collected at bridge crossings on all five brooks. More detailed assessments of the stream were conducted at the outflows of three brooks (the remaining two brooks were not accessible). These included water quality measurements (as above), elevation profiles of the stream channel and beach, and substrate description.
Sediment flowing into the Bras d’Or Lakes from the five brooks in this study was also measured directly using sediment traps. With the help of Dr. Bruce Hatcher of Cape Breton University, sediment traps were deployed by boat near the outflows of the five streams of interest to measure sediment deposition. Smaller, in-stream sediment traps were also deployed in Breac Brook, Irish Cove Brook, and Campbells Brook.
Sediment traps were retrieved by boat about a month later. Dr. Hatcher’s laboratory at CBU was used to dry and ash the sediment to get an estimate of how much sediment and organic content was collected.
CABIN protocol was used to collect information on stream health of five brooks that have not been previously sampled using these methods. The streams selected were:
Breac Brook - Big Pond (N 45.91212° W 60.51520°)
Spruce Brook - Northside East Bay (N 46.00675° W 60.43654°)
MacLeods Brook - Johnstown(N 45.80504° W 60.72104°)
Soldiers Cove Brook -Soldiers Cove (N 45.69411° W 60.73297°)
Gillis Brook -Northside East Bay (N 46.02602° W 60.38499°)
CABIN sampling provides an excellent mechanism for determining stream health by looking at invertebrate assemblages, habitat characteristics, and water parameters. The data collected was entered into the national CABIN database.
Stream connectivity was measured by conducting thirty culvert assessments on streams flowing into East Bay. Culverts were assessed according to protocol developed by the Clean Annapolis River Project (CARP), and data was submitted to them for analysis by their aquatic connectivity experts. Of the culverts visited, seventeen were full barriers and seven were partial barriers; only three were not barriers to fish passage. A variety of remediation measures were recommended for these culverts, including installation of baffles and tail-water control structures, debris removal and total structure replacement.
This project was funded by the Environment Canada Atlantic Ecosystems Initiative.
Environment Canada Sedimentation Monitoring Final Report
Culvert Assessment Final Report
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