Childers, D. L., Day, J. W., Jr., and McKellar, H. N., Jr., 2000.
Twenty more years of marsh and estuarine flux studies: revisiting
Nixon (1980). In Weinstein, M. P., and Kreeger, D. A. (eds.),
Concepts and Controversies in Tidal Marsh Ecology. Dordrecht:
Kluwer, pp. 391–423.
Crump, B. C., Ducklow, H. W., and Hobbie, J. E., 2012. Estuarine
microbial food webs. In Day, J. W., Jr., Crump, B. C., Kemp,
W. M., and Yáñez-Arancibia, A. (eds.), Estuarine Ecology,
2nd edn. Hoboken: Wiley-Blackwell, pp. 263–284.
Darnell, R. M., 1967. The organic detritus problem. In Lauff,
G. (ed.), Estuaries. American Association for the Advancement
of Science, Publication, Vol. 83, pp. 374–375.
Day, J. W., Jr., Crump, B. C., Kemp, W. M., and Yáñez-Arancibia,
A. (eds.), 2012. Estuarine Ecology, 2nd edn. Hoboken: WileyBlackwell.
Deegan, L. A., and Garritt, R. H., 1997. Evidence for spatial variability in estuarine food webs. Marine Ecology Progress Series,
147, 31–47.
Hardy, A. C., 1924. The Herring in Relation to its Animal Environment I. The food and feeding habits of the herring with special
reference to the east coast of England. Fishery Investigations
London Series 2, Vol. 7, pp. 1–53.
Huxel, G. R., and McCann, K., 1998. The influence of trophic flows
across habitats. The American Naturalist, 152, 460–469.
Mann, K. H., 1988. Production and use of detritus in various freshwater, estuarine, and coastal marine ecosystems. Limnology and
Oceanography, 33, 910–930.
Newell, R. C., and Field, J. G., 1983. The contribution of bacteria
and detritus to carbon and nitrogen flow in a benthic community.
Marine Biology Letters, 4, 23–36.
Odum, W. E., 1984. Dual-gradient concept of detritus transport and
processing in estuaries. Bulletin of Marine Science, 35,
510–521.
Peterson, B., and Howarth, R., 1987. Sulfur, carbon, and nitrogen
isotopes used to trace the flow of organic matter in the salt-marsh
estuaries of Sapelo Island, Georgia. Limnology and Oceanography, 32, 1195–1213.
Peterson, B., Howarth, R., and Garritt, R., 1985. Multiple stable isotopes used to trace the flow of organic matter in estuarine food
webs. Science, 227, 1361–1363.
Polis, G. A., Anderson, W. B., and Holt, R. E., 1997. Toward an
integration of landscape and food web ecology: the dynamics
of spatially subsidized food webs. Annual Review of Ecology
and Systematics, 28, 289–316.
Pomeroy, L. R., 1974. The ocean’s food web, a changing paradigm.
Bioscience, 24, 499–504.
Power, M. E., 1992. Top-down and bottom-up forces in food webs:
do plants have primacy? Ecology, 73, 733–746.
Raffaelli, D., and Hall, S. J., 1992. Compartments and predation in
an estuarine food web. Journal of Animal Ecology, 61, 551–560.
Savoye, N., David, V., Morisseau, F., Etcheber, H., Abril, G., Billy, I.,
Charlier, K., Oggian, G., Deriennic, H., and Sautour, B., 2012.
Origin and composition of particulate organic matter in
a macrotidal estuary: the Gironde Estuary, France. Estuarine,
Coastal and Shelf Science, 108, 16–28.
Summerhayes, V. S., and Elton, C. S., 1923. Contributions to the
ecology of Spitsbergen and Bear Island. Journal of Ecology,
11, 214–287.
Winemiller, K. O., and Polis, G. A., 1996. Food webs: what can they
tell us about the world? In Polis, G. A., and Winemiller, K. O.
(eds.), Food Webs: Integration of Patterns and Dynamics. New
York: Chapman & Hall, pp. 1–22.
Cross-references
Food Chain
Food Web/Trophic Dynamics
DIAGENESIS
Steven Colbert
Department of Marine Science, University of Hawai’i at
Hilo, Hilo, HI, USA
Definition
The chemical and biological environment within sediments
is very different from the overlying water column from
which the particles settled. During burial, particles undergo
diagenesis: the transformation of sediment and organic matter by physical, biological, and chemical processes. Early
diagenesis refers to the transformations that occur while
sediments are submerged, temperatures do not exceed
140
C, and burial is less than a few 100 m (Berner, 1980).
Description
Physical processes alter sediments after deposition. Sediments are compacted by the weight of overlying sediments, which decreases the ratio of interstitial water to
sediment. If oxygen is present in overlying water, benthic
macrofauna will mix sediments. Bioturbation is most
intense near the sediment-water interface and decreases
with depth. In specific settings, soft sediments deformation structures can form, including dewatering structures,
slumped beds, and load structures.
The chemical and biological environments change with
distance from the sediment-water interface. Exchange
between interstitial water and overlying water is restricted,
allowing for the composition of interstitial water to differ
from overlying water. Moving deeper into sediments,
interstitial water becomes more reducing as oxidants are
consumed during respiration (Froelich et al., 1979). Respiration also increases the acidity of interstitial water,
reducing the pH. The composition of interstitial water is
further influenced by uptake and release of compounds
in biotic and abiotic reactions. These changes to interstitial
water chemistry allow for different transformations of
organic matter and sediments to occur.
Most organic matter deposited in sediments is removed
by respiration of benthic organisms. However, some organic
matter is transformed from characterized compounds, such
as lipids, carbohydrates, and amino acids, into
uncharacterized humic substances. This likely occurs biologically through the selective utilization of more reactive
components of organic matter, with some contribution of
abiotic recombination of smaller molecules (Burdige,
2007). Humic substances tend to be refractory, persisting
for long periods in the sediment. The diagenesis of organic
matter depends on the redox conditions, with greater preservation of humic substances under more reducing conditions.
Inorganic sediments also undergo diagenesis from
a variety of mechanisms. Sediments may be transformed
as they pass through the gut of detritus feeders. Mineral
dissolution of carbonates and silica may occur. In anoxic
sediments, oxidized minerals, such as Fe 2 O 3 and MnO 4 ,
can be removed by microbial respiration. Further, the loss
DIAGENESIS
199
Twenty more years of marsh and estuarine flux studies: revisiting
Nixon (1980). In Weinstein, M. P., and Kreeger, D. A. (eds.),
Concepts and Controversies in Tidal Marsh Ecology. Dordrecht:
Kluwer, pp. 391–423.
Crump, B. C., Ducklow, H. W., and Hobbie, J. E., 2012. Estuarine
microbial food webs. In Day, J. W., Jr., Crump, B. C., Kemp,
W. M., and Yáñez-Arancibia, A. (eds.), Estuarine Ecology,
2nd edn. Hoboken: Wiley-Blackwell, pp. 263–284.
Darnell, R. M., 1967. The organic detritus problem. In Lauff,
G. (ed.), Estuaries. American Association for the Advancement
of Science, Publication, Vol. 83, pp. 374–375.
Day, J. W., Jr., Crump, B. C., Kemp, W. M., and Yáñez-Arancibia,
A. (eds.), 2012. Estuarine Ecology, 2nd edn. Hoboken: WileyBlackwell.
Deegan, L. A., and Garritt, R. H., 1997. Evidence for spatial variability in estuarine food webs. Marine Ecology Progress Series,
147, 31–47.
Hardy, A. C., 1924. The Herring in Relation to its Animal Environment I. The food and feeding habits of the herring with special
reference to the east coast of England. Fishery Investigations
London Series 2, Vol. 7, pp. 1–53.
Huxel, G. R., and McCann, K., 1998. The influence of trophic flows
across habitats. The American Naturalist, 152, 460–469.
Mann, K. H., 1988. Production and use of detritus in various freshwater, estuarine, and coastal marine ecosystems. Limnology and
Oceanography, 33, 910–930.
Newell, R. C., and Field, J. G., 1983. The contribution of bacteria
and detritus to carbon and nitrogen flow in a benthic community.
Marine Biology Letters, 4, 23–36.
Odum, W. E., 1984. Dual-gradient concept of detritus transport and
processing in estuaries. Bulletin of Marine Science, 35,
510–521.
Peterson, B., and Howarth, R., 1987. Sulfur, carbon, and nitrogen
isotopes used to trace the flow of organic matter in the salt-marsh
estuaries of Sapelo Island, Georgia. Limnology and Oceanography, 32, 1195–1213.
Peterson, B., Howarth, R., and Garritt, R., 1985. Multiple stable isotopes used to trace the flow of organic matter in estuarine food
webs. Science, 227, 1361–1363.
Polis, G. A., Anderson, W. B., and Holt, R. E., 1997. Toward an
integration of landscape and food web ecology: the dynamics
of spatially subsidized food webs. Annual Review of Ecology
and Systematics, 28, 289–316.
Pomeroy, L. R., 1974. The ocean’s food web, a changing paradigm.
Bioscience, 24, 499–504.
Power, M. E., 1992. Top-down and bottom-up forces in food webs:
do plants have primacy? Ecology, 73, 733–746.
Raffaelli, D., and Hall, S. J., 1992. Compartments and predation in
an estuarine food web. Journal of Animal Ecology, 61, 551–560.
Savoye, N., David, V., Morisseau, F., Etcheber, H., Abril, G., Billy, I.,
Charlier, K., Oggian, G., Deriennic, H., and Sautour, B., 2012.
Origin and composition of particulate organic matter in
a macrotidal estuary: the Gironde Estuary, France. Estuarine,
Coastal and Shelf Science, 108, 16–28.
Summerhayes, V. S., and Elton, C. S., 1923. Contributions to the
ecology of Spitsbergen and Bear Island. Journal of Ecology,
11, 214–287.
Winemiller, K. O., and Polis, G. A., 1996. Food webs: what can they
tell us about the world? In Polis, G. A., and Winemiller, K. O.
(eds.), Food Webs: Integration of Patterns and Dynamics. New
York: Chapman & Hall, pp. 1–22.
Cross-references
Food Chain
Food Web/Trophic Dynamics
DIAGENESIS
Steven Colbert
Department of Marine Science, University of Hawai’i at
Hilo, Hilo, HI, USA
Definition
The chemical and biological environment within sediments
is very different from the overlying water column from
which the particles settled. During burial, particles undergo
diagenesis: the transformation of sediment and organic matter by physical, biological, and chemical processes. Early
diagenesis refers to the transformations that occur while
sediments are submerged, temperatures do not exceed
140
C, and burial is less than a few 100 m (Berner, 1980).
Description
Physical processes alter sediments after deposition. Sediments are compacted by the weight of overlying sediments, which decreases the ratio of interstitial water to
sediment. If oxygen is present in overlying water, benthic
macrofauna will mix sediments. Bioturbation is most
intense near the sediment-water interface and decreases
with depth. In specific settings, soft sediments deformation structures can form, including dewatering structures,
slumped beds, and load structures.
The chemical and biological environments change with
distance from the sediment-water interface. Exchange
between interstitial water and overlying water is restricted,
allowing for the composition of interstitial water to differ
from overlying water. Moving deeper into sediments,
interstitial water becomes more reducing as oxidants are
consumed during respiration (Froelich et al., 1979). Respiration also increases the acidity of interstitial water,
reducing the pH. The composition of interstitial water is
further influenced by uptake and release of compounds
in biotic and abiotic reactions. These changes to interstitial
water chemistry allow for different transformations of
organic matter and sediments to occur.
Most organic matter deposited in sediments is removed
by respiration of benthic organisms. However, some organic
matter is transformed from characterized compounds, such
as lipids, carbohydrates, and amino acids, into
uncharacterized humic substances. This likely occurs biologically through the selective utilization of more reactive
components of organic matter, with some contribution of
abiotic recombination of smaller molecules (Burdige,
2007). Humic substances tend to be refractory, persisting
for long periods in the sediment. The diagenesis of organic
matter depends on the redox conditions, with greater preservation of humic substances under more reducing conditions.
Inorganic sediments also undergo diagenesis from
a variety of mechanisms. Sediments may be transformed
as they pass through the gut of detritus feeders. Mineral
dissolution of carbonates and silica may occur. In anoxic
sediments, oxidized minerals, such as Fe 2 O 3 and MnO 4 ,
can be removed by microbial respiration. Further, the loss
DIAGENESIS
199