Fringing Wetlands

Still being drafted

I paddled the shores of the entire lake, except for a bit at the northeast corner (which I covered later in August) on Aug 10, 2017. The purpose was to provide a preliminary documentation of the wetlands that fringe the lake. Specimens of the aquatic plants were taken for ID, and many photos.

There is relatively narrow band of emergent wetland vegetation – or next to none – along the borders of Sandy Lake except at
– the extreme Southwest where there is a major inlet to the lake,
– the southeast corner
– around “the peninsula” in the second southeast corner
– the northwest corner of the lake.

These latter areas correspond to broader, shallower areas viewable in Ed Glover’s Lidar image of the Sandy Lake.

Three species account for most of the emergent vegetation we see in the wetland fringes: Juncus militaris (bayonet rush), Schoenoplectus tabernaemontani (syn Scirpus validus, softstem bulrush), and Pontedariadata cordata (pickerel weed). The bayonet rush is by far the most abundant. The softstem bulrush occurs on a limited stretch of shore line just north of the Sandy Beach Park. Pickerel weed is abundant towards the edges of the broader shallower areas. Another 10-15 species are common (I am working on a species list/photos.)

Ecological role of the fringing wetlands

The fringing wetlands play vital roles in the lake ecology. They stabilize the shorelines, trap silt and organic debris coming in via streams, and provide protective habitat for frogs, turtles, and nesting loons, amongst other species.

Frogs are especially abundant in the fringing wetlands which afford protection from the voracious smallmouth bass always nearby. Clarence Stevens released fledgling snapping turtles into fringing wetland by Sandy Beach on October 7, 2017.

Traditionally Sandy Lake has supported a pair of loons which usually nest somewhere in the broader expanses of wetland at the south end of the lake, far enough from shore to avoid predation by land predators such as raccoons, weasels, and skunks. (On shallow rocky lakes in Nova Scotia, they nest on small islands away from shore; there are no such islands in Sandy Lake.)

Aquatic plants as indicators
One purpose in documenting these wetlands is to provide a monitoring baseline. The emergent aquatics are readily visible. Changes in the species and extent of the major emergent aquatics could indicate changes in variables not so readily measured such as trophic (nutrient) status.

It is notable that the bayonet rush predominates the fringe wetlands, except closer to the mouth of the inlet at the southwest corner. It is notable because in two studies, this species has been found in oligotrophic (nutrient poor) lakes, and not in more nutrient rich lakes. So its dominance and also the relatively low species diversity of the wetland fringes seem to suggest that currently the lake is not experiencing significant eutrophication, i.e. is a ‘healthy’ lake.

Species more characteristic of higher nutrient status are found close to the mouth of the inlet at the southwest corner (documentation tin prep.) In that area, the more extensive wetlands are likely acting as a “nutrient sump”, tying up excessive nutrients coming in via HP Brook. So there is a delicate balance in the lake, and we can look to the emergent aquatics as indicators of the state of that balance.

Restricted distribution of the softstem bullrush

Scirpus validus the softstem bulrush is largely or wholly restricted to a piece of shorline just north of Sandy Beach. Over the more northerly part of its distribution, bayonet rush also occurs but outside of the softstem bullrush; there is little direct overlap. Proceeding northard, bayonet rush increases and the softstem bulrush declines and disappears after you go by the small headland. DS said the section of the shore where softstem bulrush is a little pocket that is better protected from predominant winds than elsewhere on that shore.

View album Sandy Lake (Bedford, NS): Wetland Fringe