The Macrophyte Survey Report Is Out

The first Sylvan Lake macrophyte survey report is posted on the ALMS website.

Here’s how Alyssa Cloutier, our ALMS lake tech in 2014, and marine assistant SLWSS director Devon Shouldice, collected data on aquatic plants that grow in the littoral zone near the lake shore:

The entire perimeter of Sylvan Lake was sampled mainly in 500 m to 1 km intervals. Initially, transects of four points at four different depths were to be taken at each interval. However, the lack of macrophytes even at the shallowest depth prompted a change in methodology. Areas more dominant in macrophytes were sampled more rigorously, with multiple sampling points, while areas with bare or near bare sediment were sampled only once. Voucher samples were taken for each species observed and submitted for archiving at the University of Alberta herbarium.

Here’s what the project found:

Sampling took place on June 26, 2014. Early in the season the lake was very clear, with a Secchi depth of 4.25 m. Aquatic plants were sampled along the littoral zone in water depths ranging from 0.9 m to 5.9 m. Five species were collected and identified. The two dominant species in June were Sheathing Pondweed (Potamogeton vaginatus) and Richardson’s pondweed (Potamogeton richardsonii) with 10 and 8 occurrences, respectively. Of 92 sampling locations, there were 23 occurrences of macrophytes. No invasive species were detected. 

The second sampling trip occurred on July 23, 2014. A secchi disk reading of 4.5 m was observed in the center of the lake. Sampling locations occurred at depths ranging from 0.5 m to 4.2 m. The dominant species in found in June were also the dominant species in July. Over the month of growth, there was an increase in diversity as well as number of occurrences. A larger diversity and density of macrophytes was noticeable in the area just outside the marina, as well as the area in the north portion of the lake where the creek enters. Six more species were observed in July than in June. Of 78 sampling locations there were 62 occurrences of macrophytes (this may include multiple species observed in a single location). Eleven different species were observed. No invasive species were detected.

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