current levels due to the retention of water in ice sheets
that covered parts of North America, northern Europe,
and other regions on earth.
Cross-references
Climate Change
MEIOFAUNA
Rolando Bastida-Zavala and Carmen Méndez-Trejo
Laboratorio de Sistemática de Invertebrados Marinos,
Universidad del Mar Campus Puerto Angel, Puerto Angel,
Oaxaca, Mexico
Definition
Meiofauna are defined by Guiere (2009) as small mobile
and sometimes sessile benthic organisms ranging in size
between that of the microfauna and macrofauna. They
include benthic organisms that pass through a sieve mesh
size of 500 mm (or 1,000 mm) as the upper limit, and are
retained on a sieve mesh size of 44 mm (or 63 mm) as the
lower limit. Meiofauna are often found moving between
sediment interstices, but also occur on hard surfaces,
algae, coral rubble, or other surfaces. There are both temporary and permanent members of meiofaunal communities in estuarine environments. Although the meiofauna
are diminuitive forms, they can play a role in the bioturbation of bottom sediments. Important groups of meiofauna
found in estuaries include the rotifers, gastrotrichs, nematodes, polychaetes, tartigrades, copepods, turbellarians, and
ostracods.
Bibliography
Guiere, O., 2009. Meiobenthology: The microscopic motile fauna of
aquatic sediments, 2nd edn. Heidelberg: Springer.
Cross-references
Benthic Ecology
Infauna
Macrofauna
Microfauna
Soft Sediment Communities
MICROBIAL DEGRADATION
Monia El Bour
Marine Microbiology Unit, Department of Marine
Biotechnology and Biodiversity, National Institute of
Sea Sciences and Technologies (INSTM), Tunis, Tunisia
Synonyms
Biodegradation; Mineralization
Definition
Microbial degradation refers to microbial action that
drives biogeochemical cycles, notably with respect to
major elements (carbon, nitrogen, sulfur, phosphorus,
iron), as well as the breakdown of contaminants that can
be used as a microbial food source or substrate.
Description
In marine ecosystems, dissolved organic matter (DOM)
constitutes the largest amount of biologically reactive
organic carbon equal to the amount of carbon dioxide
(CO2) in the earth’s atmosphere and other sources
(terrestrial or marine). Cycling of dissolved organic
carbon significantly influences the global carbon cycle
(Kirchman et al., 2009). A large amount of DOC derives
from phytoplankton primary production (Khodse and
Bhosle, 2011).
Biodegradation or microbial mineralization is an
important process for the removal of riverine DOC in estuarine and coastal marine waters, where the biologically
reactive fraction of the riverine organic matter may be
partially or completely mineralized. Thus, many estuaries
may be considered net heterotrophic systems, with respiration exceeding primary production (He et al., 2010). In
many estuaries worldwide, a net loss of riverine particulate organic carbon (POC) has been reported, while the
DOC often exhibits an apparent conservative behavior
(Servais and Garnier, 2006).
In estuaries, biodegradation by heterotrophic bacteria
can change rapidly along the estuarine gradient, showing
a selective removal of carbohydrates and amino acids
within the DOC pool in the upper reach and mixing zone
and an autotrophic source of particulate carbohydrates
(PCHO) in the lower estuary. These differences provide
insight into the DOC process in estuaries (He et al.,
2010).
Bibliography
He, B., Dai, M., Zhai, W., Wang, L., Wang, K., Chen, J., Lin, J.,
Han, A., and Xu, Y., 2010. Distribution, degradation and
dynamics of dissolved organic carbon and its major compound
classes in the Pearl River estuary, China. Marine Chemistry,
119, 52–64.
Kirchman, D. L., Moran, X. A. G., and Ducklow, H., 2009.
Microbial growth in the polar oceans-role of temperature and
potential impact of climate change. Nature Reviews Microbiology, 7, 451–459.
Khodse, V. B., and Bhosle, N. B., 2011. Bacterial utilization of
size fractionated dissolved organic matter. Aquatic Microbial
Ecology, 64, 299–309.
Servais, P., and Garnier, J., 2006. Organic carbon and bacterial
heterotrophic activity in the maximum turbidity zone of the
Seine estuary (France). Aquatic Sciences, 68, 78–85.
Cross-references
Bioremediation
Carbon Sequestration
Microbial Survivability
MICROBIAL DEGRADATION
433
that covered parts of North America, northern Europe,
and other regions on earth.
Cross-references
Climate Change
MEIOFAUNA
Rolando Bastida-Zavala and Carmen Méndez-Trejo
Laboratorio de Sistemática de Invertebrados Marinos,
Universidad del Mar Campus Puerto Angel, Puerto Angel,
Oaxaca, Mexico
Definition
Meiofauna are defined by Guiere (2009) as small mobile
and sometimes sessile benthic organisms ranging in size
between that of the microfauna and macrofauna. They
include benthic organisms that pass through a sieve mesh
size of 500 mm (or 1,000 mm) as the upper limit, and are
retained on a sieve mesh size of 44 mm (or 63 mm) as the
lower limit. Meiofauna are often found moving between
sediment interstices, but also occur on hard surfaces,
algae, coral rubble, or other surfaces. There are both temporary and permanent members of meiofaunal communities in estuarine environments. Although the meiofauna
are diminuitive forms, they can play a role in the bioturbation of bottom sediments. Important groups of meiofauna
found in estuaries include the rotifers, gastrotrichs, nematodes, polychaetes, tartigrades, copepods, turbellarians, and
ostracods.
Bibliography
Guiere, O., 2009. Meiobenthology: The microscopic motile fauna of
aquatic sediments, 2nd edn. Heidelberg: Springer.
Cross-references
Benthic Ecology
Infauna
Macrofauna
Microfauna
Soft Sediment Communities
MICROBIAL DEGRADATION
Monia El Bour
Marine Microbiology Unit, Department of Marine
Biotechnology and Biodiversity, National Institute of
Sea Sciences and Technologies (INSTM), Tunis, Tunisia
Synonyms
Biodegradation; Mineralization
Definition
Microbial degradation refers to microbial action that
drives biogeochemical cycles, notably with respect to
major elements (carbon, nitrogen, sulfur, phosphorus,
iron), as well as the breakdown of contaminants that can
be used as a microbial food source or substrate.
Description
In marine ecosystems, dissolved organic matter (DOM)
constitutes the largest amount of biologically reactive
organic carbon equal to the amount of carbon dioxide
(CO2) in the earth’s atmosphere and other sources
(terrestrial or marine). Cycling of dissolved organic
carbon significantly influences the global carbon cycle
(Kirchman et al., 2009). A large amount of DOC derives
from phytoplankton primary production (Khodse and
Bhosle, 2011).
Biodegradation or microbial mineralization is an
important process for the removal of riverine DOC in estuarine and coastal marine waters, where the biologically
reactive fraction of the riverine organic matter may be
partially or completely mineralized. Thus, many estuaries
may be considered net heterotrophic systems, with respiration exceeding primary production (He et al., 2010). In
many estuaries worldwide, a net loss of riverine particulate organic carbon (POC) has been reported, while the
DOC often exhibits an apparent conservative behavior
(Servais and Garnier, 2006).
In estuaries, biodegradation by heterotrophic bacteria
can change rapidly along the estuarine gradient, showing
a selective removal of carbohydrates and amino acids
within the DOC pool in the upper reach and mixing zone
and an autotrophic source of particulate carbohydrates
(PCHO) in the lower estuary. These differences provide
insight into the DOC process in estuaries (He et al.,
2010).
Bibliography
He, B., Dai, M., Zhai, W., Wang, L., Wang, K., Chen, J., Lin, J.,
Han, A., and Xu, Y., 2010. Distribution, degradation and
dynamics of dissolved organic carbon and its major compound
classes in the Pearl River estuary, China. Marine Chemistry,
119, 52–64.
Kirchman, D. L., Moran, X. A. G., and Ducklow, H., 2009.
Microbial growth in the polar oceans-role of temperature and
potential impact of climate change. Nature Reviews Microbiology, 7, 451–459.
Khodse, V. B., and Bhosle, N. B., 2011. Bacterial utilization of
size fractionated dissolved organic matter. Aquatic Microbial
Ecology, 64, 299–309.
Servais, P., and Garnier, J., 2006. Organic carbon and bacterial
heterotrophic activity in the maximum turbidity zone of the
Seine estuary (France). Aquatic Sciences, 68, 78–85.
Cross-references
Bioremediation
Carbon Sequestration
Microbial Survivability
MICROBIAL DEGRADATION
433