Falkowski, P. G., and Raven, J. A., 2007. Aquatic Photosynthesis.
Princeton: Princeton University Press.
Stumm, W., and Morgan, J. J., 1996. Aquatic Chemistry: Chemical
Equilibria, and Rates in Natural Waters, 3rd edn. New York:
John Wiley & Sons.
Cross-references
Estuarine Circulation
Nutrient Limitation
Phytoplankton
MICROPHYTOBENTHOS
Lawrence Cahoon
Department of Biology & Marine Biology, University of
North Carolina Wilmington, Wilmington, NC, USA
Synonyms
Benthic microalgae
Definition
The microphytobenthos are microscopic autotrophs associated with benthic substrates. They are usually found as
single cells but may also occur as filamentous or colonial
forms. Some species are firmly attached to substrates,
e.g., most monoraphic and biraphic diatoms, while others
are loosely attached or not at all, or even motile, as with
benthic dinoflagellates. “Epipsammic” forms are associated with sandy substrates, “epipelic” forms with muddy
substrates, “epilithic” forms with rocky or other hard substrates, and “epiphytic” and “epizooic” forms with
macroflora and macrofauna, respectively.
Taxonomy
The microphytobenthos are usually dominated by pennate
diatoms (Bacillariophyceae, Pennales), but not exclusively so. Some centric diatoms (Centrales) are also predominantly benthic in life mode. Other autotroph taxa
frequently found in microphytobenthos assemblages
include dinoflagellates, cyanobacteria, chlorophytes,
and euglenoids. Superior resistance of siliceous diatom
frustules to damage during sampling and laboratory examination may bias taxonomic assessments of the
microphytobenthos.
Ecological significance
The microphytobenthos are frequently important in estuarine ecosystems in terms of biomass, production, and trophic significance and also participate in nutrient cycling
and the consolidation of sediments. Comprehensive
reviews of the importance of microphytobenthos in estuarine ecosystems have been published by MacIntyre
et al. (1996), Miller et al. (1996), and Underwood and
Kromkamp (1999).
Bibliography
MacIntyre, H. L., Geider, R. J., and Miller, D. C., 1996. Microphytobenthos: the ecological role of the “Secret Garden” of
unvegetated, shallow-water marine habitats. I. Distribution,
abundance, and primary production. Estuaries, 19, 186–201.
Miller, D. C., Geider, R. J., and MacIntyre, H. L., 1996. Microphytobenthos: the ecological role of the “Secret Garden” of
unvegetated, shallow-water marine habitats. II. Role in sediment
stability and shallow-water food webs. Estuaries, 19, 202–212.
Underwood, G. J. C., and Kromkamp, J., 1999. Primary production
by phytoplankton and microphytobenthos in estuaries. Advances
in Ecological Research, 29, 93–153.
Cross-references
Autotrophic
Benthic Ecology
Cyanobacteria
MINERALIZATION
Vic Semeniuk
V & C Semeniuk Research Group, Warwick, WA,
Australia
Synonyms
Conversion of organic compounds
Definition
Mineralization, as it relates to estuaries, refers to the
conversion of organic compounds, and those organic
compounds with N, P, S, or C, to free inorganic radicals
and ions available for biotic uptake, the formation of inorganic mineral or mineral/organic inclusions and structures
in plants and animals, the biomediated precipitation of
minerals, the inorganic precipitation from aqueous solution of mineral substances, and the (diagenetic) inorganic
transformation of one mineral to another. All of the above
processes can occur in estuarine environments.
Types of mineralization
Mineralization has different meanings depending on the
scientific discipline or subdiscipline where the term is
being applied, and to separate them, specific adjectives
or suffixes are used herein. Ecologists, biologists, and
biochemists view mineralization as the conversion via
biochemical breakdown, often facilitated by microbes, of
organic compounds and organic compounds with molecular attachments (attached radicals, or functional groups or
substituents, or ligands), such as NH 4 , NO 3 , SO 4 , PO 4 ,
and CO 3 , to inorganic molecules and ions and the transformation of organic compounds to free C-bearing ions or
C-bearing molecules. Effectively, this is the process of
converting organic compounds to inorganic compounds
and ions. The inorganic ions are then available for plant
uptake by macrophytes in tidal and aquatic environments,
by benthic diatoms and phytoplankton, or further
438
MICROPHYTOBENTHOS
Princeton: Princeton University Press.
Stumm, W., and Morgan, J. J., 1996. Aquatic Chemistry: Chemical
Equilibria, and Rates in Natural Waters, 3rd edn. New York:
John Wiley & Sons.
Cross-references
Estuarine Circulation
Nutrient Limitation
Phytoplankton
MICROPHYTOBENTHOS
Lawrence Cahoon
Department of Biology & Marine Biology, University of
North Carolina Wilmington, Wilmington, NC, USA
Synonyms
Benthic microalgae
Definition
The microphytobenthos are microscopic autotrophs associated with benthic substrates. They are usually found as
single cells but may also occur as filamentous or colonial
forms. Some species are firmly attached to substrates,
e.g., most monoraphic and biraphic diatoms, while others
are loosely attached or not at all, or even motile, as with
benthic dinoflagellates. “Epipsammic” forms are associated with sandy substrates, “epipelic” forms with muddy
substrates, “epilithic” forms with rocky or other hard substrates, and “epiphytic” and “epizooic” forms with
macroflora and macrofauna, respectively.
Taxonomy
The microphytobenthos are usually dominated by pennate
diatoms (Bacillariophyceae, Pennales), but not exclusively so. Some centric diatoms (Centrales) are also predominantly benthic in life mode. Other autotroph taxa
frequently found in microphytobenthos assemblages
include dinoflagellates, cyanobacteria, chlorophytes,
and euglenoids. Superior resistance of siliceous diatom
frustules to damage during sampling and laboratory examination may bias taxonomic assessments of the
microphytobenthos.
Ecological significance
The microphytobenthos are frequently important in estuarine ecosystems in terms of biomass, production, and trophic significance and also participate in nutrient cycling
and the consolidation of sediments. Comprehensive
reviews of the importance of microphytobenthos in estuarine ecosystems have been published by MacIntyre
et al. (1996), Miller et al. (1996), and Underwood and
Kromkamp (1999).
Bibliography
MacIntyre, H. L., Geider, R. J., and Miller, D. C., 1996. Microphytobenthos: the ecological role of the “Secret Garden” of
unvegetated, shallow-water marine habitats. I. Distribution,
abundance, and primary production. Estuaries, 19, 186–201.
Miller, D. C., Geider, R. J., and MacIntyre, H. L., 1996. Microphytobenthos: the ecological role of the “Secret Garden” of
unvegetated, shallow-water marine habitats. II. Role in sediment
stability and shallow-water food webs. Estuaries, 19, 202–212.
Underwood, G. J. C., and Kromkamp, J., 1999. Primary production
by phytoplankton and microphytobenthos in estuaries. Advances
in Ecological Research, 29, 93–153.
Cross-references
Autotrophic
Benthic Ecology
Cyanobacteria
MINERALIZATION
Vic Semeniuk
V & C Semeniuk Research Group, Warwick, WA,
Australia
Synonyms
Conversion of organic compounds
Definition
Mineralization, as it relates to estuaries, refers to the
conversion of organic compounds, and those organic
compounds with N, P, S, or C, to free inorganic radicals
and ions available for biotic uptake, the formation of inorganic mineral or mineral/organic inclusions and structures
in plants and animals, the biomediated precipitation of
minerals, the inorganic precipitation from aqueous solution of mineral substances, and the (diagenetic) inorganic
transformation of one mineral to another. All of the above
processes can occur in estuarine environments.
Types of mineralization
Mineralization has different meanings depending on the
scientific discipline or subdiscipline where the term is
being applied, and to separate them, specific adjectives
or suffixes are used herein. Ecologists, biologists, and
biochemists view mineralization as the conversion via
biochemical breakdown, often facilitated by microbes, of
organic compounds and organic compounds with molecular attachments (attached radicals, or functional groups or
substituents, or ligands), such as NH 4 , NO 3 , SO 4 , PO 4 ,
and CO 3 , to inorganic molecules and ions and the transformation of organic compounds to free C-bearing ions or
C-bearing molecules. Effectively, this is the process of
converting organic compounds to inorganic compounds
and ions. The inorganic ions are then available for plant
uptake by macrophytes in tidal and aquatic environments,
by benthic diatoms and phytoplankton, or further
438
MICROPHYTOBENTHOS