Most aquatic plants are found in the near shore portions of the waterbody where sunlight penetrates to the bottom sediments. This portion of the lake, pond or stream is called the littoral zone. As water clarity and the bathymetry vary widely from one waterbody to another, the outer depth of the littoral zone also varies. The plants that grow in the littoral zone can be conceptually grouped into distinct communities. In reality, however, there is a good deal of overlap between communities.
EMERGENT PLANT COMMUNITY: This area extends from the wet shoreline soils into relatively shallow (knee-deep) water. With stiff but buoyant leaves and tough interlocking roots, emergent plants are well adapted to life at the water’s edge where wave action and fluctuating water levels are common. The plants in this community play an important role in protecting water quality by preventing shoreline erosion and the resuspension of fine bottom sediments. They also provide important food and cover for insects, fish and waterfowl. Native plants commonly found in the emergent plant community (also referred to as “wetland” plants) include: cattails, arrowheads, pickerel weed, sedges and rushes. Though there are invasive emergent plant species that threaten Maine’s wetlands, none is currently prohibited by law as are the eleven aquatic plants on Maine’s invasive aquatic plant list.
FLOATING-LEAVED PLANT COMMUNITY: This area extends from the wet shoreline to chest deep water. Plants in this group are distinguished by tough, waxy leaves adapted to float on the surface of the water. Some floating-leaved plants have long, elastic leaf stalks extending to the bottom sediments. Others are free-floating. Native plants commonly found in this community include: fragrant waterlilies, watershield, spatterdock, and little floating heart. Three of the eleven invasive aquatic plants on Maine’s list are found in this community: European frogbit, yellow floating heart, and water chestnut.
SUBMERSED PLANT COMMUNITY: This area extends from the shallowest depths to the deepest waters of the littoral zone. Plants in this community are adapted to life below the water surface, though many produce emergent or floating flowers that appear at or above the surface later in the growing season. Native plants found in this community may include: coontail, bladderworts, pondweeds, and the native water-milfoils. Eight of the eleven invasive aquatic plants on Maine’s invasive aquatic plant list are found in this community: Brazilian waterweed, curly-leaf pondweed, Eurasian water-milfoil, European naiad, fanwort, hydrilla, parrot feather, and variable water-milfoil.
Water Quality Monitoring
Aquatic Invasive Monitoring
Maine Volunteer Lake Monitoring Program
24 Maple Hill Road, Auburn, ME 04210
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