Freshwater and marine coast ecology 93foraging and animal dispersal are most important in urban-region planning,
since these strongly depend on the sizes and arrangements of habitats.
Freshwater and marine coast ecology
Wenow turn to diverse types of water bodies, their aquatic ecosystems,
and their immediately surrounding land. The first big topic,freshwater,includes
hydrology, groundwater, wetlands, streams, rivers, lakes, and urban-region
effects. The other complex topic,marine coasts,includes rocky shores, sandy beach
strips, coastal wetlands, estuarine bays, various saltwater ecosystems, dynamic
forces, and urban-region effects.
Freshwater
Thehydrologic cycle,describing the accumulations and flows of water on
Earth, is a simple way to begin (Ahrens 1991 , Moran and Morgan1994,Smith
1996,Wetzel2001,Odum and Barrett2005). Water accumulates as water vapor in
theatmosphere, as liquid inwaterbodies(i.e., groundwater, lakes, streams/rivers,
and seas), and as ice in mountain and polar glaciers. Cooling the water vapor
produces precipitation (rain and snow) which falls on land and water. Some
rainwater soaks into the ground and some moves across the land in streams and
rivers to the sea.Evapotranspirationfrom the land and plants, plus evaporation
from water bodies, sends water vapor back to the atmosphere, completing the
cycle.
Deep groundwater is normally in anaquifer,i.e., a porous rock or sandy area
full of water, suggestive ofanundergroundlake(Gibertet al.1994). Except in
limestone areas, water at the upper surface of an aquifer moves very slowly,
often only tens of meters or a few hundred meters a year, so pollutants reaching
an aquifer tend to accumulate.Shallow groundwaterwithin meters of the ground
surface saturates earth and soil spaces, with thewatertablebeing the top of
thesaturated zone. Shallow groundwater flows through the ground into, and
commonly helps maintain, surface water bodies such as streams and lakes. It
also sustains plant roots and vegetation.
Wetlandshave water at or above the ground surface for prolonged periods
most years, with marshes (dominated by herbaceous plants, such as grasses and
sedges) having the longest inundation period, peatlands (often dominated by
shrubs and peat moss) commonly intermediate, and swamps (dominated by trees)
shorter inundation seasons (Salvesen1994,Smith1996,Keddy2000,Mitschand
Gosselink2000,Parsonset al.2002). The seasonal rises and falls of water level,
plus microhabitat heterogeneity, are important wetland characteristics. In most