Sand-Jensen, K., and Borum, J., 1991. Interactions among phytoplankton, periphyton, and macrophytes in temperate freshwaters
and estuaries. Aquatic Botany, 41, 137–175.
Seitzinger, S. P., Pilling, I. E., and Dekorsey, R., 1993. Eutrophication and nutrient loading in Barnegat Bay: N or P limitation of
primary production. Final Report to the New Jersey. Trenton,
NJ: Department of Environmental Protection.
Seitzinger, S. P., Styles, R. M., and Pilling, I. E., 2001. Benthic
microalgal and phytoplankton production in Barnegat Bay,
New Jersey (USA): microcosm experiments and data synthesis.
Journal of Coastal Research, SI32, 144–162.
Vaughan, A. E., 1982. Production Ecology of Eelgrass (Zostera
marina) and its Epiphytes in Little Egg Harbor, New Jersey.
PhD thesis, New Brunswick, NJ, Rutgers University.
EVAPORATION AND TRANSPIRATION
Vic Semeniuk
V & C Semeniuk Research Group, Warwick,
WA, Australia
Definition
Evaporation. The physical process whereby water as
liquid or moisture is converted to vapor.
Transpiration. The process whereby water is evaporated
from the leaves, stems, and flowers of a plant.
Description
Evaporation and transpiration result in the export of water
as vapor from estuaries and their coastal environments and
tidal flats, causing water loss, desiccation, salinization,
and physiological stress of biota. The effect of evaporation
on estuaries and their peripheral tidally exposed environments can be substantial in regions with high solarinduced evaporation and those with strong coastal winds.
In tropical arid climates, high evaporation (e.g.,
3,000 mm/pa) and strong coastal winds (>20–30 km/h)
commonly occur together.
Estuarine water bodies, their coastal zones, and tidal
flats are subject to the evaporative effects of solar radiation
and wind. Evaporation of a shallow estuarine water body
over a year (or years), if there is little recharge from rivers
and microtidal conditions, will concentrate salt. At
extremes, evaporation results in periodic hypersalinity in
the upper estuary (an inverse estuary).
Evaporation in coastal habitats and tidal flats will result
in salinization of sediments and physiological stress of biota
(by direct desiccation and by salinization). This is particularly so for tidal flats as they tend to be relatively wide with
laterally extensive surfaces exposed to sun and wind, providing large surface areas for moisture loss. During low
tide, water under exposed tidal flats occurs as a shallow
water table (the top of a phreatic zone that is contiguous
with and tidally oscillating with open estuarine waters)
and as pore water (a vadose zone in the sediment above
the water table) – evaporation causes their salinity to
increase. With a low-gradient sloping surface, tidal flats
are graded with respect to inundation, and salinity thus
increases upslope because of the progressively longer exposure to evaporative processes, where groundwater and pore
water salinity may reach 100–150 ppt. This gradient of
salinity underpins the biological zoning on the tidal flat as
each species responds to the various levels of inundation
and salinity. Evaporation directly desiccates tidal flat
biota, physiologically stressing them, and this process also
determines biological occurrence and zonation. Increase in
salinity of groundwater and pore water, in addition, may
progress to the point that minerals such as calcite and gypsum precipitate in sediments as crystals, layers, or nodules.
For transpiration, since most of the plants that transpire
are tidal (samphires, reeds, rushes, sedges, or mangroves),
the most marked water vapor loss by this process is on
vegetated tidal flats. Transpiration draws on pore water
and shallow groundwater, thus concentrating salt and
augmenting the salinization of tidal flat induced by sun
and wind. The rates of transpiration for saltmarsh and
mangroves are variable across species and related to the
size and density of plants, season (generally higher in
the dry season than the wet), time of day, and salinity
of the tidal flat. For plants of the saltmarsh, transpiration
can vary from $1 to 6 mmol m
À2
s
À1 ; for mangroves,
they vary from 0.5 to 7.0 mmol m
À2
s
À1 (and generally
2–4 mmol m
À2 s
À1
) (Adam, 1990; Kathiresan and
Bingham, 2001; Saenger, 2002). As such, transpiration
can be a significant factor in moisture loss in vegetated
peripheral estuarine environments.
Bibliography
Adam, P., 1990. Saltmarsh Ecology. Cambridge: Cambridge
University Press.
Kathiresan, K., and Bingham, B. L., 2001. Biology of mangroves
and mangrove ecosystems. Advances in Marine Biology, 40,
81–251.
Saenger, P., 2002. Mangrove Ecology, Silviculture and Conservation. Dordrecht: Kluwer Academic.
Cross-references
Mangroves
Saltmarshes
Tidal Flat
Tidal Flat Salinity Gradient
EXOTIC SPECIES
Francisco Barros
Laboratório de Ecologia Bentônica,
Instituto de Biologia, Universidade Federal da Bahia,
Salvador, Bahia, Brazil
Synonyms
Alien species; Introduced species; Non-native species
EXOTIC SPECIES
311
and estuaries. Aquatic Botany, 41, 137–175.
Seitzinger, S. P., Pilling, I. E., and Dekorsey, R., 1993. Eutrophication and nutrient loading in Barnegat Bay: N or P limitation of
primary production. Final Report to the New Jersey. Trenton,
NJ: Department of Environmental Protection.
Seitzinger, S. P., Styles, R. M., and Pilling, I. E., 2001. Benthic
microalgal and phytoplankton production in Barnegat Bay,
New Jersey (USA): microcosm experiments and data synthesis.
Journal of Coastal Research, SI32, 144–162.
Vaughan, A. E., 1982. Production Ecology of Eelgrass (Zostera
marina) and its Epiphytes in Little Egg Harbor, New Jersey.
PhD thesis, New Brunswick, NJ, Rutgers University.
EVAPORATION AND TRANSPIRATION
Vic Semeniuk
V & C Semeniuk Research Group, Warwick,
WA, Australia
Definition
Evaporation. The physical process whereby water as
liquid or moisture is converted to vapor.
Transpiration. The process whereby water is evaporated
from the leaves, stems, and flowers of a plant.
Description
Evaporation and transpiration result in the export of water
as vapor from estuaries and their coastal environments and
tidal flats, causing water loss, desiccation, salinization,
and physiological stress of biota. The effect of evaporation
on estuaries and their peripheral tidally exposed environments can be substantial in regions with high solarinduced evaporation and those with strong coastal winds.
In tropical arid climates, high evaporation (e.g.,
3,000 mm/pa) and strong coastal winds (>20–30 km/h)
commonly occur together.
Estuarine water bodies, their coastal zones, and tidal
flats are subject to the evaporative effects of solar radiation
and wind. Evaporation of a shallow estuarine water body
over a year (or years), if there is little recharge from rivers
and microtidal conditions, will concentrate salt. At
extremes, evaporation results in periodic hypersalinity in
the upper estuary (an inverse estuary).
Evaporation in coastal habitats and tidal flats will result
in salinization of sediments and physiological stress of biota
(by direct desiccation and by salinization). This is particularly so for tidal flats as they tend to be relatively wide with
laterally extensive surfaces exposed to sun and wind, providing large surface areas for moisture loss. During low
tide, water under exposed tidal flats occurs as a shallow
water table (the top of a phreatic zone that is contiguous
with and tidally oscillating with open estuarine waters)
and as pore water (a vadose zone in the sediment above
the water table) – evaporation causes their salinity to
increase. With a low-gradient sloping surface, tidal flats
are graded with respect to inundation, and salinity thus
increases upslope because of the progressively longer exposure to evaporative processes, where groundwater and pore
water salinity may reach 100–150 ppt. This gradient of
salinity underpins the biological zoning on the tidal flat as
each species responds to the various levels of inundation
and salinity. Evaporation directly desiccates tidal flat
biota, physiologically stressing them, and this process also
determines biological occurrence and zonation. Increase in
salinity of groundwater and pore water, in addition, may
progress to the point that minerals such as calcite and gypsum precipitate in sediments as crystals, layers, or nodules.
For transpiration, since most of the plants that transpire
are tidal (samphires, reeds, rushes, sedges, or mangroves),
the most marked water vapor loss by this process is on
vegetated tidal flats. Transpiration draws on pore water
and shallow groundwater, thus concentrating salt and
augmenting the salinization of tidal flat induced by sun
and wind. The rates of transpiration for saltmarsh and
mangroves are variable across species and related to the
size and density of plants, season (generally higher in
the dry season than the wet), time of day, and salinity
of the tidal flat. For plants of the saltmarsh, transpiration
can vary from $1 to 6 mmol m
À2
s
À1 ; for mangroves,
they vary from 0.5 to 7.0 mmol m
À2
s
À1 (and generally
2–4 mmol m
À2 s
À1
) (Adam, 1990; Kathiresan and
Bingham, 2001; Saenger, 2002). As such, transpiration
can be a significant factor in moisture loss in vegetated
peripheral estuarine environments.
Bibliography
Adam, P., 1990. Saltmarsh Ecology. Cambridge: Cambridge
University Press.
Kathiresan, K., and Bingham, B. L., 2001. Biology of mangroves
and mangrove ecosystems. Advances in Marine Biology, 40,
81–251.
Saenger, P., 2002. Mangrove Ecology, Silviculture and Conservation. Dordrecht: Kluwer Academic.
Cross-references
Mangroves
Saltmarshes
Tidal Flat
Tidal Flat Salinity Gradient
EXOTIC SPECIES
Francisco Barros
Laboratório de Ecologia Bentônica,
Instituto de Biologia, Universidade Federal da Bahia,
Salvador, Bahia, Brazil
Synonyms
Alien species; Introduced species; Non-native species
EXOTIC SPECIES
311