University of Minnesota
University of Minnesota
College of Biological Sciences
Cedar CreekDragonflyCedar Bog Lake

Aquatic Communities

Aquatic habitats found on the area include Fish Lake (a large shallow sand-bottomed lake), Beckman Lake and Cedar Bog Lake (two bog-margined lakes), Ice Lake, Beaver Pond, and several other smaller permanent ponds that are bounded by emergent marsh. A number of ordinarily temporary/vernal ponds or pools are also found in the area. Finally, Cedar Creek is a small meandering muck-bottomed stream that is bounded by sedge fen and shrub swamp. Each of the larger bodies of water has its own unique character and will be considered separately.

Cedar Bog Lake

Cedar Bog Lake lies in a swampy matrix of white cedar swamp and is surrounded by a mat of Decodon verticillata (Swamp Loosestrife). This late-flowering species turns crimson in the fall and is a species of special concern in Minnesota. It is found primarily at a few shallow lakes on the Anoka Sandplain. This is the lake where Raymond Lindeman did his pioneering work on trophic dynamics in aquatic ecosystems. According to Dr. Eville Gorham it might more properly be called ‘Tamarack Swamp Pond’ as it is rather small, not really a bog, and is immediately bounded by tamaracks. Another name that has been proposed is ‘Decodon Pond’ emphasizing the importance of this uncommon plant. Water, though dark-stained, is circumneutral. Only stunted bullheads, tiny sunfish, and sticklebacks are found in this small, shallow, muck-bottomed lake. Waterfowl generally ignore it, but occasionally otter will visit it from the creek nearby. It and the surrounding swamps have received the attention of several paleobotanists including Herb Wright and Ed Cushing.

Fish Lake

Fish Lake is large (ca 3 mile perimeter), shallow (90% less than 2 meters deep), and sand-bottomed along the east shore while muck-bottomed along the western shore. Shallows of the mucky western portion support a population of Zizania palustris (Wild Rice). Nymphaea tuberosa, Nuphar luteum, and Brasenia schreberi (White and Yellow Water Lilies, Water Shield) grow luxuriantly from this mucky substrate. A typical spectrum of submerged aquatics is present. Circa 7 species of Potamogeton are found in the lake. P. amplifolius is the most common. Najas flexilis (Water Naiad) forms an impenetrable mass below the Pondweeds. Other common submerged aquatics are Utricularia vulgaris (Bladderwort), Ceratophyllum demersum (Coontail), Elodea canadensis (Elodea), Myriophyllum sibiricum (Water-milfoil), Vallisneria americana (Tape Grass), Ranunculus flabellaris (Yellow Water Crowfoot). Off the sandy east shore we find Scirpus validus (Softstem Bulrush), S. acutus (Hardstem Bulrush), S. pungens (Three-square Bulrush), and three species of Arrowheads (Saggitaria latifolia, S. cristata, S. rigida).

Special Feature

During periods of low water an expanse of sand beach is exposed along the shoreline of Fish Lake where one encounters a dizzying array of plants. Heteranthera dubia (Water Star Grass) and Hemicarpha micrantha grow on a lush carpet of the tiny Spike Rush, Eleocharis acicularis. Several other species of Eleocharis are present as well as species of Juncus (tenuis, nodosus, pelocarpa) and Cyperus (diandra, engelmanni, xx). In later summer the shoreline is brightened by such species as Eupatorium perfoliatum (Boneset), Verbena hastata (Blue Vervain), Lobelia siphilitica (Blue Lobelia), Mimulus ringens (Square-stem Monkey Flower), and Agalinis tenuifolia (Gerardia).

Vertebrates of Fish Lake

Fish Lake is in some sense a misnomer. Because it is so shallow, it suffers periodic winter kills of most fish inhabiting it. Indeed, from 1973 to 1983, there were no fish in it at all, only mudminnows and sticklebacks. However, it was an enormous breeding pond for dragonflies. Millions of individuals of three species (Epitheca spinigera, Ladona julia, Gomphus spicatus) would emerge from this lake during a brief period in late May. They dominated the lake until 1983. Since then the lake has undergone several cycles when fish were abundant or scarce. Ca. 1985 bluegills, pumpkinseeds and to a lesser extent crappies were abundant. Ca. 1988 largemouth bass dominated the lake and consumed everything else in it. In the early 1990s the lake was again fishless. The latter half of the 1990s saw an explosion of green sunfish. They were so numerous that one could literally dip net them from the lake. Presently (2001) they too have died out and the lake has again become a prolific producer of dragonflies.

A canoeist on the lake will undoubtedly spot numerous painted turtles sunning themselves on uprooted lily root-stocks during the summer, and on more than one occasion I have been startled by a monster snapping turtle swimming in the shallows.

Every year since 1973 a single pair of Common Loons has attempted to nest on the lake. About half the time they succeed in producing one or two young. Infrequently, one witnesses spectacular chases as two pairs contest for the lake soon after ice out in mid April. Other birds of note are Great Blue and Green Herons, Belted Kingfishers, Sora and Virginia Rails. Canada Geese began nesting on the lake ca 1990 and have gradually increased in abundance, but do not reach the pest proportions found on many city area lakes. Occasional visitants to the lake are Bald Eagle, Osprey, and Trumpeter Swans. Black Terns nested on the lake for a brief period during the mid 1970s. The lake sees an influx of migrating waterfowl during spring and fall (incl. bluebills, hooded mergansers, buffleheads, pie-billed and eared grebes, coots…)

The lake has always supported at least one family of beaver. Position of the lodge(s) changes over the years. Infrequently there is an explosion of muskrat that exploit the cattails of Peterson Marsh bounding the lake on the west. Otter occasionally visit the lake in the fall for a sunfish snack.

Beckman Lake

Beckman Lake is most noteworthy for its floating mat margin of sphagnum moss (Sphagnum spp) with numerous species of graminoids, ericaceous shrubs, and carnivorous pitcher plants and sundew. (See section on Sphagnum Communities.) The best bog margins of the lake are found in the southwest corner and at the extreme north end. The entire eastern shore is fronted by private land. Several of these homeowners have dug artificial ponds in the marshy margin of the lake. These ponds are bermed, but they do pose a threat to the fragile, nutrient poor communities found along the lake’s perimeter. Among the more noteworthy aquatics in the neutral waters of the lake are Scirpus subterminalis and Equisetum fluviatile.

Beaver Pond is surrounded by emergent marsh (primarily sedge and cattail). Two featurse of note are the presence of Pontederia cordata (Pickerelweed) and a respectable patch of Equisetum fluviatile (Water Horsetail). During mid-summer the entire surface of this pond is choked with Nuphar luteum (Yellow Pond Lily). It is an excellent waterfowl hangout in the fall when ducks are chased from Fish Lake by hunters.

Temporary Ponds

Temporary Ponds are fringed by a variety of wide-bladed sedges. Some of the more common are C. lacustris, C. rostrata, C. comosa … In early April these ponds ring with the sound of spring peepers, chorus frogs, and woodfrogs. Chorusing can be so loud as to be almost deafening. Soon thereafter one hears the less cacaphonic trilling of green tree frogs and American toads. If these ponds dry out in mid summer they become production centers for species of Bidens (Beggarticks) and Polygonum (Smartweeds). A stroll through them at this time is sticky business.

Cedar Creek

Cedar Creek is of rather ordinary character although the views it offers a canoeist can be superb. The broad basin, margined in sedge fen and shrub swamp, gives way in the distance to golden tamarack (in late fall), white cedars, and pine covered ridges. One can easily imagine being in some remote area of northern Minnesota. A skier along the snow-packed marsh margin of the creek on a mild winter day will likely encounter otter slides, and if extremely lucky, otter themselves. On more than one occasion we have been tempted to canoe the creek on a warm sunny day in mid February only to be foiled by ice-covered meanders in its mid-section. Extracting oneself from this predicament is no easy task as some of the gullibles who have accompanied us can attest. Several beaver dams are additional obstacles encountered on a trip down the creek. But these inconvenient portages are made up for by sightings of Blandings turtles along the way. During mid-summer extensive mudflats are exposed along the creek’s many meanders and these are alive with the mating antics of dragonflies like the ebony jewelwing (Calopteryx aequabilis), the white-tail (Plathemis lydia) and the 10-spotter (Libellula pulchella). Cedar Creek joins the Rum River ca 8 miles to the southwest and the Rum eventually drains into the Mississippi River near Anoka. In addition to myriad minnows and numerous carp, anglers occasionally catch a respectable smallmouth bass, walleye or northern pike from the creek.