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ECOSYSTEMS
Environments
printable pageValue of Groundwater Ecosystems
Groundwater ecosystems provide important services in the environment. Water is purified through microbial processes that remove pathogens and eliminate chemical contaminants. These ecosystems recycle organic matter transported by water and redistribute energy and matter over areas ranging from a few millimeters to meters. Groundwater also contributes to the sustainability of surface ecosystems. (Danielopol et al., 2003)
Three environments associated with groundwater are discussed here: aquifers (completely subterranean), caves (habitats formed by groundwater), and surface ecosystems (habitats sustained by groundwater).
Aquifer
Organisms living underground within the aquifer are subject to extremely uniform conditions compared with surface life. There is very little diversity of habitat type, conditions such as temperature vary only slightly, and darkness is permanent. Species living in groundwaters need special adaptations to survive. Many have elongate body forms to facilitate movement through small openings. The lack of eyes and body pigment is common, as is the increased development of other sensory organs such as antennae. Groundwater organisms are more commonly found near the surface, where oxygen and food are more abundant. This is especially true in the hyporheic zone ? the area under and to the sides of rivers. (Scarsbrook et al., 2000)
Caves
Caves are natural openings in rock that are large enough for humans to enter (Gunn, 2004). Organisms that live exclusively in caves are subject to some of the same conditions as those that live within the aquifer, although there is slightly more variation in temperature and habitat type in caves. Because caves are usually larger than most pore spaces within an aquifer, macro-organisms are more common in caves than in the aquifer. Because caves are open to the surface, their faunas are often similar to that of surface ecosystems.
Surface Ecosystems
In many areas groundwater is responsible for maintaining the hydrologic balance of surface streams, springs, lakes, wetlands, and marshes. While rainfall on these areas may be seasonal, groundwater can provide a year-round source of water and prevent the damage that would result from a drought otherwise. Due to the seasonal nature of rainfall in some areas, surface ecosystems may draw groundwater during the dry season and contribute recharge to the aquifer during the wet season. (Fetter, 2004)
Groundwater ecosystems provide important services in the environment. Water is purified through microbial processes that remove pathogens and eliminate chemical contaminants. These ecosystems recycle organic matter transported by water and redistribute energy and matter over areas ranging from a few millimeters to meters. Groundwater also contributes to the sustainability of surface ecosystems. (Danielopol et al., 2003)
 Macro-organisms (body size >2mm) include vertebrates and crayfish. Meio-organisms (body size 0.02-2mm) are mainly small crustaceans and worms. Micro-organisms (body size <0.02mm) include bacteria, protozoans, and fungi. Modified from Danielopol et al. (2003). |
Aquifer
Organisms living underground within the aquifer are subject to extremely uniform conditions compared with surface life. There is very little diversity of habitat type, conditions such as temperature vary only slightly, and darkness is permanent. Species living in groundwaters need special adaptations to survive. Many have elongate body forms to facilitate movement through small openings. The lack of eyes and body pigment is common, as is the increased development of other sensory organs such as antennae. Groundwater organisms are more commonly found near the surface, where oxygen and food are more abundant. This is especially true in the hyporheic zone ? the area under and to the sides of rivers. (Scarsbrook et al., 2000)
Caves
Caves are natural openings in rock that are large enough for humans to enter (Gunn, 2004). Organisms that live exclusively in caves are subject to some of the same conditions as those that live within the aquifer, although there is slightly more variation in temperature and habitat type in caves. Because caves are usually larger than most pore spaces within an aquifer, macro-organisms are more common in caves than in the aquifer. Because caves are open to the surface, their faunas are often similar to that of surface ecosystems.
Surface Ecosystems
In many areas groundwater is responsible for maintaining the hydrologic balance of surface streams, springs, lakes, wetlands, and marshes. While rainfall on these areas may be seasonal, groundwater can provide a year-round source of water and prevent the damage that would result from a drought otherwise. Due to the seasonal nature of rainfall in some areas, surface ecosystems may draw groundwater during the dry season and contribute recharge to the aquifer during the wet season. (Fetter, 2004)
