Brook Trout usually live in freshwater habitats, although some coastal populations have the ability to move between freshwater and saltwater habitats. This material introduces a variety of surface water habitats found in the Northeast. Whether it is a stream, lake or marsh, each of these watery habitats is a type of wetland. Although wetlands are sometimes undervalued, they are crucial habitats and provide many benefits to wildlife and humans. Wildlife count on wetlands for food, shelter, and breeding sites. The benefits to humans can be environmental, economic, aesthetic, recreational and educational.
Wetland is a term used to describe land that is inundated or saturated by freshwater, saltwater, or a combination of the two for at least part of the growing season and is home to specialized plants that grow in saturated soils. In some situations wetland soils are so saturated with water that there is not enough oxygen within the soil for aerobic decomposers to do their jobs. Sometimes under these conditions organisms must rely on anaerobic respiration. Anaerobic bacteria, with the help of sulfur compounds, carry out their metabolic processes producing as a byproduct hydrogen sulfide, a gas that gives marshes a characteristic rotten egg smell.
Wetlands form from a combinatin of factors including glaciation, climate, agriculture and hydrologic processes. Beavers are also well known for their ability to create wetlands. Each type of wetland is a unique ecosystem with its own inherent values and functions. Wetlands are among the most fertile, productive and threatened ecosystems in the world.
While a technical discussion of wetlands classifications is beyond the scope of this guide, an introduction to the breadth and value off wetland systems is worthwhile. Wetlands are classified for management purposes based upon plant and soil types and the frequency of flooding. More detailed descriptions of specific wetland types and their inhabitants are located in the publications listed below.
The Northeast has both inland and coastal wetland systems. Inland wetlands that incorporate a river or stream are called riverine wetlands. Wetlands that include a permanently flooded lake or reservoir are called lacustrine. Wetlands that are dominated by trees, shrubs and emergent vegetation are called palustrine. Coastal wetlands that include open ocean and are affected by waves are called marine wetlands, while areas that are partially enclosed by land, have negligible wave action, and contain a mixture of freshwater and saltwater are called estuarine. Palustrine wetland systems often border riverine, lacustriene and estuarine systems.
Each type of wetland is distinguished by its physical and chemical characteristics and by the types of plants and animals that live there. However, many plants and animals may be found in more than one wetland type.
Water flowing to the sea may take the form of a stream or a river. These streams and rivers belong to the riverine wetlands system. Steams and rivers are unique habitats because flowing water creates conditions that are constantly changing. Headwater streams are particularly important places for trout and salmon because they build their redds (nests) and lay their eggs in the gravel bottom beds.
Headwater streams are typically shallow, narrow, clear and cool. The cool temperature and mixing action of the fast-flowing water make headwater streams high in dissolved oxygen. The major source of productivity in these streams is the overhanging trees that drop their leaves and associated creatures into the stream below. These bits of decaying leaves and twigs are callled detritus. As these streams accumulate water and widen, periphyton (diatoms and other algae clinging to rocks) may become another important source of primary productivity. As a stream continues to widen downstream it becomes a river; emergent macrophytes (rooted plants that grow partly in and partly out of water) may take over some of the food production role in the stream or river.
Stream inhabitats include animals that graze on periphtyon, filter feed from flowing water, shred bits of detritus or prey on other organisms within the stream. These include snails, protozoans, mussels, blackflies, mayflies, midges, salamanders and trout. Steams attract a number of terrestrial animals to their edges as well. The vegetated edges of streams might include trees and shrubs, grasses and sedges, and many other plants.
Rivers, like streams, are characterized by flowing water and changing conditions. However, large rivers are in some ways similar to ponds and lakes. Large slow rivers, like lakes, are usually deeper, wider, more turbid and warmer than smaller fast flowing steams. Mud, silt, sand or clay, rather than cobble, cover the bottoms of large slow rivers. Emergent macrophytes and phytoplankton (free-floating algae) may be a part of the base of the food chain. Additional nutrients flow in from upstream releases and soil erosion, and are washed in from connected wetlands.
There is somewhat less diversity (variety of living organisms) in large rivers than in streams because the shifting substrate of sand, silt or mud reduces the amount of aeration, buries benthic (bottom-dwelling) animals and does not provide adequate stabiltiy for rooted aquatic plants. Rivers are home to a number of types of animals such as zooplankton, damselflies, leeches, waterstriders, worms, frogs, turtles, mink and others. The fish that live in large rivers are often similar to fish one might find in a pond. Bass, yellow perch, catfish and carp live in river habitats.
Lacustrine habitats include the wetlands and deep-water habitats of permanently flooded lakes and large reservoirs. They will have some wave action. Large areas of deep open water create a habitat for a variety of fish and wildlife. Fish draw people and wildlife to lacustrine habitats. Northern pike, yellow perch, pickerel, carp, bass and bluegill live in the lakes of the Northeast. These species attract fish-eating birds such as the belted kingfisher, common merganser, common loons, ospery and bald eagles. These birds will often nest near good sources of food.
Aquatic plants in lakes attract waterfowl such as mallards, black ducks and common goldeneyes. Moose are also attracted to lakes and ponds in northern regions during the summer when they are searching for aquatic plants to eat. Bullfrogs, newts and turtles live in and near Northeastern lakes. Sometimes mink and river otters will live in dens adjacent to lakes that have enough fish and other types of aquatic prey.
The most common type of wetlands in the Northeast are palustrine. Palustrine habitats are wetlands dominated by trees, shrubs, persistent emergents, emergent mosses or lichens. Palustrine wetlands include marshes, swamps, bogs, wet meadows, fens and wet prairies. Small shallow ponds are also considered palustrine wetlands. Pallustrine habitats are characterized by a diversity of plant species and structural features that provide feeding, breeding, nesting, overwintering and migration habitat for wildlife. There are several classes of palustrine wetlands.
Forested palustrine wetlands are dominated by trees and are sometimes called wooded swamps or, in the South, bottom-lands. Red maple, white cedar and black spruce trees are often found in a palustrine forested wetland. Typical shrubs include highbush blueberry, swamp azalea and silky dogwood. Cinnamon and sensitive fern, as well as skunk cabbage, spotted jewelweed, sphagnum moss and goldthread inhabit the forested palustrine wetland. Many species of animals use the forested palustrine wetlands of the Northeast. An example is the wood duck.
Vernal pools in the forested palustrine wetlands are depressions that fill up with water during wet seasons, but dry up at other times. Vernal pools are important breeding areas for amphibians such as salamanders and frogs. Fairy shrimp also rely on vernal pools. They lay drought-resistant eggs that hatch when the pool fills with water. Vernal pools are extremely productive valuable ecosystems that are often overlooked and undervalued.
Palustrine scrub-shrub wetlands are dominated by woody species in the sapling and shrub stages. Vegetation in these wetlands includes the highbush blueberry, sweet pepperbush, willow, alder and spicebush. Associated herbs often include cinnamon fern, spotted jewelweed, sphagnum moss, sedges, rushes and hydrophilic (water loving) grasses. Scrub-shrub wetlands frequently flood in the spring or contain pockets of standing water.
Wildlife use the palustrine scrub-shrub wetlands for feeding, nesting, breeding and cover. Songbirds, for example, may nest in the same dense shrubs in which they feed on berries or insects. A sampling of birds found in scrub-shrub wetlands includes alder flycatcher and American woodcock. Amphibians such as the spring peeper and gray tree frog use flooded shrub swamps as breeding ponds in the spring They in turn attract predators such as the great blue heron, raccoon and mink. Yellowthroats are a common bird.
Palustrine emerergent wetlands are dominated by herbaceous or non-woody vegetation and usually have either surface water or saturated soils year-round. Marshes and wet meadows are two familiar palustrine emergent wetlands. Cattails, blue flag, water willow and other sedges, rushes and grasses are common in freshwater marshes. Plants such as smartweeds, arrow-leaved tearthum and pickerelweed are also common in marshes. Wet meadows tend to be somewhat drier than marshes. Plants such as rush, soft rush, wool grass, spotted jewelweed, joe-pye weed, sensitive fern, meadowsweet, steeplebush, tussock sedges, sweet flag, and hydrophilic grasses are typical in wet meadows.
Purple loosestrife and common phragmites reed are two species of non-native vegetation that are often found in palustrine emergent wetlands. They are sometimes refered to as "invasive" plants because they become established fairly easily in disturbed soils, growing and spreading quickly. An effect of these invasive species is diminished biological diversity and loss of food and habitat for diverse wildliffe.
Red-wing blackbirds breed and nest in cattail marshes. Examples of other songbirds that nest and/or feed in marshes and wet meadows include the swamp sparrow and marsh wren. Wading birds, such as the American bittern, great blue heron and common snipe, use marshes to find food and shelter. Waterfowl, such as mallards, use the emergent vegetation of these wetlands for feeding and nesting. Mammals that feed or hunt in marshes include raccoons, mink and muskrats. Small mammals that burrow in the soft soils of marshes and wet meadows include the short-tailed shrew and meadow jumping mouse. Some reptiles and amphibians feed, breed, and overwinter in palustrine emergent wetlands.
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