M
MACROALGAE
Michael J. Kennish
Department of Marine and Coastal Sciences,
School of Environmental and Biological Sciences,
Rutgers University, New Brunswick, NJ, USA
Synonyms
Seaweeds
Definition
Macroalgae, commonly termed seaweeds, are
multicellular, macroscopic benthic algae belonging to
green (phylum Chlorophyta), red (phylum Rhodophyta),
and brown (phylum Phaeophyta) taxonomic groups. They
are found in estuaries throughout the world attached to
substrates or drifting in the water column. Benthic
macroalgae generally attain highest abundance in shallow
estuaries and coastal lagoons where the estuarine floor lies
within the photic zone.
Characteristics
Macroalgae exhibit a range of body types, including filamentous, leafy, sheetlike, tubular, branching, and feathery
forms. They can reproduce sexually or asexually. In shallow estuaries and coastal lagoons, macroalgae often attain
high diversity; for example, more than 100 species of
macroalgae have been recorded in Barnegat Bay-Little
Egg Harbor, a coastal lagoon in New Jersey (USA)
(Kennish, 2001). In addition, they often generate high
biomass, particularly during bloom events, when they typically form thick mats covering extensive areas of the estuarine floor or wetland surface (McGlathery et al., 2007). In
nutrient enriched waters, macroalgal populations may
reach a peak biomass of more than 0.5 kg m
À2
, with
canopy heights exceeding 0.5 m (McGlathery, 2001).
Temperature, light, nutrients, and grazing pressure are
mechanisms that control the rates of net production
in macroalgae (Valiela et al., 1997), which are important
habitat formers for many estuarine organisms. While
some macroalgae inhabiting estuaries belong to a drift
community unattached to any substrate, others attach to
rocks, bulkheads, piers, and other hard substrates by
root-like holdfasts or basal disks. On mudflats, epipelic,
epipsammic, or drift populations typically predominate.
In estuaries, macroalgae disperse as free-floating forms
or as microscopic propagules (spores, gamete, and
zygotes), and hence currents play a significant role in their
distribution. Macroalgae frequently display a distinct
zonation in intertidal zones, notably on rocky shores. This
distribution is largely controlled by tidal variation, competition for light, desiccation (emersion), and grazing.
Common macroalgal taxa in estuaries include the
following: Cladophora, Enteromorpha, and Ulva
(Chlorophyta); Ascophyllum, Fucus, and Sphacelaria
(Phaeophyta); and Ceramium, Gracilaria, and
Polysiphonia (Rhodophyta).
Bibliography
Kennish, M. J., 2001. Benthic communities of the Barnegat
Bay-Little Egg Harbor Estuary. Journal of Coastal Research,
SI 32, 167–177.
McGlathery, K. J., 2001. Macroalgal blooms contribute to the
decline of seagrass in nutrient enriched coastal waters. Journal
of Phycology, 37, 453–456.
McGlathery, K. J., Sundbäck, K., and Anderson, I. C., 2007. Eutrophication in shallow coastal bays and lagoons: the role of plants
in the coastal filter. Marine Ecology Progress Series, 348, 1–18.
Valiela, I., McClelland, J., Hauxwell, J., Behr, P. J., Hersh, D., and
Foreman, K., 1997. Macroalgal blooms in shallow estuaries:
controls and ecophysiological and ecosystem consequences.
Limnology and Oceanography, 42, 1105–1118.
M.J. Kennish (ed.), Encyclopedia of Estuaries, DOI 10.1007/978-94-017-8801-4,
© Springer Science+Business Media Dordrecht 2016
MACROALGAE
Michael J. Kennish
Department of Marine and Coastal Sciences,
School of Environmental and Biological Sciences,
Rutgers University, New Brunswick, NJ, USA
Synonyms
Seaweeds
Definition
Macroalgae, commonly termed seaweeds, are
multicellular, macroscopic benthic algae belonging to
green (phylum Chlorophyta), red (phylum Rhodophyta),
and brown (phylum Phaeophyta) taxonomic groups. They
are found in estuaries throughout the world attached to
substrates or drifting in the water column. Benthic
macroalgae generally attain highest abundance in shallow
estuaries and coastal lagoons where the estuarine floor lies
within the photic zone.
Characteristics
Macroalgae exhibit a range of body types, including filamentous, leafy, sheetlike, tubular, branching, and feathery
forms. They can reproduce sexually or asexually. In shallow estuaries and coastal lagoons, macroalgae often attain
high diversity; for example, more than 100 species of
macroalgae have been recorded in Barnegat Bay-Little
Egg Harbor, a coastal lagoon in New Jersey (USA)
(Kennish, 2001). In addition, they often generate high
biomass, particularly during bloom events, when they typically form thick mats covering extensive areas of the estuarine floor or wetland surface (McGlathery et al., 2007). In
nutrient enriched waters, macroalgal populations may
reach a peak biomass of more than 0.5 kg m
À2
, with
canopy heights exceeding 0.5 m (McGlathery, 2001).
Temperature, light, nutrients, and grazing pressure are
mechanisms that control the rates of net production
in macroalgae (Valiela et al., 1997), which are important
habitat formers for many estuarine organisms. While
some macroalgae inhabiting estuaries belong to a drift
community unattached to any substrate, others attach to
rocks, bulkheads, piers, and other hard substrates by
root-like holdfasts or basal disks. On mudflats, epipelic,
epipsammic, or drift populations typically predominate.
In estuaries, macroalgae disperse as free-floating forms
or as microscopic propagules (spores, gamete, and
zygotes), and hence currents play a significant role in their
distribution. Macroalgae frequently display a distinct
zonation in intertidal zones, notably on rocky shores. This
distribution is largely controlled by tidal variation, competition for light, desiccation (emersion), and grazing.
Common macroalgal taxa in estuaries include the
following: Cladophora, Enteromorpha, and Ulva
(Chlorophyta); Ascophyllum, Fucus, and Sphacelaria
(Phaeophyta); and Ceramium, Gracilaria, and
Polysiphonia (Rhodophyta).
Bibliography
Kennish, M. J., 2001. Benthic communities of the Barnegat
Bay-Little Egg Harbor Estuary. Journal of Coastal Research,
SI 32, 167–177.
McGlathery, K. J., 2001. Macroalgal blooms contribute to the
decline of seagrass in nutrient enriched coastal waters. Journal
of Phycology, 37, 453–456.
McGlathery, K. J., Sundbäck, K., and Anderson, I. C., 2007. Eutrophication in shallow coastal bays and lagoons: the role of plants
in the coastal filter. Marine Ecology Progress Series, 348, 1–18.
Valiela, I., McClelland, J., Hauxwell, J., Behr, P. J., Hersh, D., and
Foreman, K., 1997. Macroalgal blooms in shallow estuaries:
controls and ecophysiological and ecosystem consequences.
Limnology and Oceanography, 42, 1105–1118.
M.J. Kennish (ed.), Encyclopedia of Estuaries, DOI 10.1007/978-94-017-8801-4,
© Springer Science+Business Media Dordrecht 2016