accretion

the gradual build up of surface elevations due to the deposition of suspended sediments on the marsh surface

aquatic

in or near water in such habitats as ponds, lakes, rivers and oceans

back-barrier marsh

a marsh that forms in the low-lying area behind a barrier beach formation

barrier beach

an elongated landform created by the deposition of sedimentary materials by wind and wave currents, usually parallel to the shoreline, with water on at least two sides, and composed of sand, gravel, or cobblestones

brackish marsh

tidal marshes where the average water salinity is less than 18 parts per thousand (ppt) but greater than 0.5 ppt, which is the upper limit of salinity in a freshwater tidal wetland

buffer zone

an undeveloped area bordering on a wetland that serves to lessen the impact of disturbance (e.g., urban development)

deepwater habitats

permanently flooded areas deeper than 6.6 feet (e.g., lakes)

degraded

characterized by loss of natural ecological structure or function

dominant plant community

a single species or association of plants that are indicative of the ecology of an area, e.g. in a cattail marsh the dominant plant community is cattails

drainage pattern

the paths followed by surface runoff from precipitation within a watershed

ecology

the study of interactions between living things and their environment

ecological integrity

the natural (undisturbed) quality of an ecosystem

ecosystem

a community of plants and animals and the physical environment they inhabit (such as estuaries and tidal wetlands) which results from the interactions among soil, climate, vegetation, and animal life

emergent plant

erect, rooted, herbaceous plants that can tolerate flooded soil conditions, but not prolonged periods of being completely submerged, these include grasses, sedges, rushes, and rooted aquatic plants; there are two types of emergent plants:

estuary

areas where saltwater from the ocean mixes with freshwater from inland rivers and surface runoff

evaluation unit (EU)

subsection of a tidal marsh delineated by tidal restrictions used as the basic unit for evaluation of the marsh system

fill

material, usually associated with the dredging of a harbor or inlet, placed on the surface of the marsh; the change in elevation caused by the disposal of this material in the marsh can lead to the loss of the area as a functioning tidal marsh

freshwater source

the point of origin of nontidal waters including rivers, streams and surface runoff

freshwater tidal marshes

marshes that are tidally influenced, but where the average water salinity is less than 0.5 parts per thousand

geomorphology

the study of the natural processes involved in the creation of landforms such as tidal marshes and barrier beaches

habitat

the environment in which the requirements of a specific plant or animal are met

herbaceous plant

a non-woody plant with a soft stem (e.g., bulrushes and cattails)

high marsh

areas of tidal marshes that are irregularly flooded (frequently beyond the reach of daily flooding) and are typically dominated by salt hay grass (Spartina patens)

hydrology

the scientific study of the properties, circulation, and distribution of water as it occurs in the atmosphere and at the earth’s surface as streamflow, precipitation, soil moisture, and ground water

hydrologic regime

the frequency and duration of flooding and/or saturation

hydroperiod

the duration of typical flooding/saturation events; in tidal marshes, the hydroperiod can range from daily flooding to irregular flooding (e.g., every few days, weeks, or months); depends on the marsh elevation

intertidal emergent

an erect rooted herbaceous plant growing in the intertidal zone

intertidal zone

areas that are alternately exposed and flooded by tides

invasive species

plant species that, when introduced to an ecosystem, can disturb the natural balance and habitat diversity by invading and dominating the natural tidal marsh plant community, frequently establishing dense monotypic (single species) stands of vegetation

low marsh

areas of marsh that are flooded twice a day and are dominated by saltwater cordgrass (Spartina alterniflora)

marine

relating to ocean environments

marsh hydrology

this term describes (1) the hydrologic pathways such as precipitation, surface runoff, ground water, tidal fluctuations and flooding rivers which transport nutrients to and from wetlands; (2) the water depth; (3) frequency and duration of flooding in tidal marshes

marsh peat

the organic soil formed by the accumulation of dead marsh plant material and trapped sediments from tidal waters

marsh restoration

improvement of existing marsh condition by reversing some of the adverse impacts caused by coastal development

marsh system

an area of marsh associated with a single opening to the ocean, a single freshwater input, or adjacent to and contiguously along the shore of a tidal river or bay

mitigation

activities taken to minimize or offset wetland impacts due to development or construction. Restoration and enhancement of existing wetlands or creation of new wetlands are forms of impact mitigation

non point source

a pollution source that does not come from a single point. Typical non-point sources include parking lots, roads, and agricultural fields

open water

areas within or adjacent to a marsh that are below mean low water and greater than 100 meters wide (330 feet); this manual uses an arbitrary division of 100 meters to distinguish between open water and tidal creeks

organic matter

a combination of decayed and decaying plant and animal residue

overland flow

a term to describe the sheet-like flow of water over a land surface, not concentrated in individual channels; usually associated with areas of low infiltration such as paved surfaces or surfaces lacking vegetation (see also surface runoff)

pannes

shallow ponds that form on the surface of the marsh and hold salt water between tides

point source

a pollution source that comes from an identifiable point, such as a factory discharge pipe or septic system outlet

primary consumer

animals that eat plant material as their main source of energy

sea level

the level of the surface of the ocean at its mean (average) position between high and low tide

sheet flow

unchannelized flow of water across the surface of a marsh or upland

subsidence

a sinking of the marsh surface, through compaction and degradation of marsh peat; often occurs when Spartina patens is deprived of tidal flow

spit

a small point of land, especially sand or gravel, formed by the deposition of material by wind and water currents that runs into a body of water

spring high tide

tides associated with the full and new moon that are higher and lower than the average tide

staddle

a structure consisting of numerous pilings driven into the marsh on which to stack salt hay to keep it above the tidewaters until it could be hauled off

substrate

the type of bottom sediments such as sand, gravel, peat

surface runoff

the movement of water over the land surface (usually in defined channels), resulting from rainfall or snowmelt; percentage of precipitation that becomes runoff varies depending on the slope of the area, the degree of soil saturation, amount of vegetated coverage, or type of surface e.g. paved areas

tidal amplitude

the variations in the height of tides caused by the lunar cycle, elevation above sea level, the barometric pressure, tidal restrictions and the seasons

tidal creeks

streams in the tidal marsh that are less than 100 meters wide at mean low water and whose main source of water is dominated by tidal action

tidal flats

areas that are irregularly exposed and are devoid of emergent vegetation, also called mud flats or unconsolidated bottom

transition zone

area surrounding a wetland where conditions gradually change from wetland biota to upland biota

turbidity

the clarity of the water column as determined by the presence of suspended particles making the water cloudy

upland islands

areas of upland soils and vegetation located within a tidal marsh

vegetated tidal marsh

marshes dominated by emergent vegetation and influenced by the tides

watershed wetlands

the area from which all water including precipitation, streams and rivers drain to a single point those areas that are inundated or saturated by surface or ground water, support a prevalence of vegetation adapted to life in saturated conditions (i.e., hydrophytes), and are characterized by hydric soils; these include bogs, marshes, swamps, wet meadows, and similar areas

Zone of Influence

area surrounding a wetland in which the activities that take place have an impact on the wetland; the Maine Citizens Tidal Marsh Guide considers a 1/2 mile Zone of Influence, with particular focus on activities within the 250 foot shoreland Zone