Sandy Lake & Environs (Bedford, Nova Scotia)

View Item No. 15.3.2, Halifax Regional Council November 12, 2024

This document includes a Staff Report dated Apr 22, 2024, and the full LakeWatchers State of the Lakes Report, 2022-2023 SAMPLING YEARS

“Environment and Sustainability Standing Committee received a staff recommendation report dated April
22, 2024 to consider an in-depth analysis of the 2022-23 LakeWatchers program, a program initiated to monitor the water quality of 73 lakes in Halifax Regional Municipality (HRM). Continue reading →

Bottle with Sandy Lake water
Click on images for larger version. Viewed at max size, individual clumps of cells/colonies appear as small beads – approx 0.25 mm diameter, they can just be discriminated with the naked eye.

Circumstantial evidence suggests the appearance of “green aggregations” on the shoreline on the west side of the lake followed fall turnover of the water column, bringing up phosphorus-rich water from the hypolimnion which stimulated growth of a nitrogen-fixing BGA (Cyanobacterium), the ID confirmed by specialists to be Dolichospermum  flos-aquae.

On Thursday, Nov 7th of 2024,  D.S., a resident of Sandy Lake, arrived at my doorstep with a small bottle of Sandy Lake water he had collected along the shore on the west side of the lake in the late afternoon of Nov 6th.

It had a very distinctive layer of green near its top (pic at right).

“Green Aggregations” by the shore, west side of Sandy Lake
Nov 6, 2024

He showed me photos of where  he had sampled.  The next day, he said, it was gone.

I put some drops  from the green layer under my Dissection Microscope and could just barely see the individual cells. That characteristic (very small cells) and the pattern of clumping of filaments of cells suggested to me it was  a BGA (Blue Green Alga) aka “Cyanobacteria”.*
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*While the term BGA  (Blue Green Algae) remains in common use today,  these organisms are more correctly (scientifically) described not as algae but as a type of bacteria in the Phylum “Cyanobacteria“. These are photosynthetic bacteria, the light-capturing pigments sometimes giving them a blue-green colour, hence the common name. Continue reading →

The LakeWatchers Report is highly informative, exceptionally well presented, and very timely. In general our results and interpretations of them for Sandy  Lake as reported on this website are  consistent with the conclusion from the LakeWatchers conclusion that “that most Halifax-area lakes currently suffer from some level of chloride enrichment and show signs of increasing eutrophication.” I was particularly interested in the recognition and discussion of a “Total P measurement issue” (my terminology), the recently measured values seeming to be too low in relation to historical values and to other indicators of trophic status.

The LakeWatchers Report is included as “Attachment A,  for  Item No. 13.1.2, Environment & Sustainability Standing Committee October 03, 2024: Subject: LakeWatchers Water Quality Monitoring Program Report 2022-2023.

The Executive Summary for Item No. 13.1.2 provides  a concise summary of the Report: Continue reading →