instantaneous pulse in a limited portion of the estuary)
(Hagy et al., 2000).
Bibliography
Dettmann, E. H., 2001. Effect of water residence time on annual
export and denitrification of nitrogen in estuaries: a model analysis. Estuaries, 24, 481–490.
Dettmann, E. H., 2008. Turnover time. In Jørgensen, S. E., and Fath,
B. D. (eds.), Ecological Indicators, Encyclopedia of Ecology.
Oxford: Elsevier, Vol. 5, pp. 3639–3644.
Hagy, J. D., Sanford, L. P., and Boynton, W. R., 2000. Estimation of
net physical transport and hydraulic residence times for a coastal
plain estuary using box models. Estuaries, 23, 328–340.
Pilson, M. E. Q., 1985. On the residence time of water in Narragansett Bay. Estuaries, 8, 2–14.
FOOD CHAIN
Mónica Lara Uc, Rafael Riosmena-Rodríguez and
Juan M. Rodríguez-Baron
Programa de Investigación en Botãnica Marina,
Departamento Académico de Biología Marina,
Universidad Autónoma de Baja California Sur, La Paz,
Baja California Sur, Mexico
Synonyms
Trophic levels
Definition
Food chain refers to the transfer of energy (linear sequence
of links) from the base to the top of a food web. The number of trophic levels is often called the food-chain length.
Description
Food-chain length is a central characteristic of estuarine
ecosystems. It reflects the organization of trophic interactions in biotic communities (Pace et al., 1999; Persson,
1999; Oksanen and Oksanen, 2000); key ecosystem
functions, such as nutrient cycling, primary productivity,
and atmospheric carbon (C) exchange (Pace et al.,
1999); and the bioconcentration of contaminants in top
predators, including many fish that humans consume
(Spencer and Warren, 1996; Kidd et al., 1998). Conventional wisdom holds that food-chain length is determined either by the dynamic stability of food webs or
by the availability of limiting food resources (often
represented as energy). Some recent studies strongly
challenge this conventional wisdom (Post et al., 2000),
whereas others reframe the question to accommodate
functional definitions of food-chain length (Oksanen
et al., 1996). These and other studies suggest a complex
relationship between food-chain length and ecological
processes, such as the history of community
organization, resource availability, habitat stability, and
ecosystem size.
Different hypotheses predict food-chain length to
be determined by productivity alone (productivity
hypothesis) (Diehl and Feissel, 2001), ecosystem size
alone (ecosystem-size hypothesis) (Kitching, 2000], or a
combination of productivity and ecosystem size
(productive-space hypothesis). The productivity and
productive-space hypotheses propose that food-chain
length should increase with increasing resource availability; however, the productivity hypothesis does not include
ecosystem size as a determinant of resource availability.
The ecosystem-size hypothesis is based on the relationship between ecosystem size and species diversity,
habitat availability, and habitat heterogeneity (Menge
and Sutherland, 1987).
Bibliography
Diehl, S., and Feissel, M., 2001. Intraguild prey suffer from enrichment of their resources: a microcosm experiment with ciliates.
Ecology, 82, 2977–2983.
Kidd, K. A., et al., 1998. Effects of trophic position and lipid on
organochlorine concentrations in fishes from subarctic lakes in
Yukon Territory. Canadian Journal of Fisheries and Aquatic
Sciences, 55, 869–881.
Kitching, R. L., 2000. Food Webs and Container Habitats.
Cambridge: Cambridge University Press.
Kitching, R. L., 2001. Food webs in phytotelmata: ‘bottom-up’ and
‘top-down’ explanations for community structure. Annual
Review of Entomology, 46, 729–760.
Menge, B. A., and Sutherland, J. P., 1987. Community regulation:
variation in disturbance, competition, and predation in relation
to environmental stress and recruitment. American Naturalist,
130, 730–757.
Moore, J. C., et al., 1993. Influence of productivity on the stability
of real and model ecosystems. Science, 261, 906–908.
Oksanen, L., and Oksanen, T., 2000. The logic and realism of the
hypothesis of exploitation ecosystems. American Naturalist,
155, 703–723.
Oksanen, L., et al., 1996. Structure and dynamics of arctic–
subarctic grazing webs in relation to primary production.
In Polis, G. A., and Winemiller, K. O. (eds.), Food Webs: Integration of Pattern and Process. London: Chapman & Hall,
pp. 231–244.
Pace, M. L., et al., 1999. Trophic cascades revealed in diverse ecosystems. Trends of Ecology and Evolution, 14, 483–488.
Persson, L., 1999. Trophic cascades: abiding heterogeneity and
the trophic level concept at the end of the road. Oikos, 85,
385–397.
Persson, L., et al., 1996. Productivity and consumer regulation –
concepts, patterns, and mechanisms. In Polis, G. A., and
Winemiller, K. O. (eds.), Food Webs: Integration of Pattern
and Process. London: Chapman & Hall, pp. 396–434.
Pimm, S. L., 1982. Food Webs. London: Chapman & Hall.
Post, D. M., et al., 2000. Ecosystem size determines food-chain
length in lakes. Nature, 405, 1047–1049.
Power, M. E., et al., 1996. Disturbance and food chain length in
rivers. In Polis, G. A., and Winemiller, K. O. (eds.), Food Webs:
Integration of Pattern and Process. London: Chapman & Hall,
pp. 286–297.
330
FOOD CHAIN
(Hagy et al., 2000).
Bibliography
Dettmann, E. H., 2001. Effect of water residence time on annual
export and denitrification of nitrogen in estuaries: a model analysis. Estuaries, 24, 481–490.
Dettmann, E. H., 2008. Turnover time. In Jørgensen, S. E., and Fath,
B. D. (eds.), Ecological Indicators, Encyclopedia of Ecology.
Oxford: Elsevier, Vol. 5, pp. 3639–3644.
Hagy, J. D., Sanford, L. P., and Boynton, W. R., 2000. Estimation of
net physical transport and hydraulic residence times for a coastal
plain estuary using box models. Estuaries, 23, 328–340.
Pilson, M. E. Q., 1985. On the residence time of water in Narragansett Bay. Estuaries, 8, 2–14.
FOOD CHAIN
Mónica Lara Uc, Rafael Riosmena-Rodríguez and
Juan M. Rodríguez-Baron
Programa de Investigación en Botãnica Marina,
Departamento Académico de Biología Marina,
Universidad Autónoma de Baja California Sur, La Paz,
Baja California Sur, Mexico
Synonyms
Trophic levels
Definition
Food chain refers to the transfer of energy (linear sequence
of links) from the base to the top of a food web. The number of trophic levels is often called the food-chain length.
Description
Food-chain length is a central characteristic of estuarine
ecosystems. It reflects the organization of trophic interactions in biotic communities (Pace et al., 1999; Persson,
1999; Oksanen and Oksanen, 2000); key ecosystem
functions, such as nutrient cycling, primary productivity,
and atmospheric carbon (C) exchange (Pace et al.,
1999); and the bioconcentration of contaminants in top
predators, including many fish that humans consume
(Spencer and Warren, 1996; Kidd et al., 1998). Conventional wisdom holds that food-chain length is determined either by the dynamic stability of food webs or
by the availability of limiting food resources (often
represented as energy). Some recent studies strongly
challenge this conventional wisdom (Post et al., 2000),
whereas others reframe the question to accommodate
functional definitions of food-chain length (Oksanen
et al., 1996). These and other studies suggest a complex
relationship between food-chain length and ecological
processes, such as the history of community
organization, resource availability, habitat stability, and
ecosystem size.
Different hypotheses predict food-chain length to
be determined by productivity alone (productivity
hypothesis) (Diehl and Feissel, 2001), ecosystem size
alone (ecosystem-size hypothesis) (Kitching, 2000], or a
combination of productivity and ecosystem size
(productive-space hypothesis). The productivity and
productive-space hypotheses propose that food-chain
length should increase with increasing resource availability; however, the productivity hypothesis does not include
ecosystem size as a determinant of resource availability.
The ecosystem-size hypothesis is based on the relationship between ecosystem size and species diversity,
habitat availability, and habitat heterogeneity (Menge
and Sutherland, 1987).
Bibliography
Diehl, S., and Feissel, M., 2001. Intraguild prey suffer from enrichment of their resources: a microcosm experiment with ciliates.
Ecology, 82, 2977–2983.
Kidd, K. A., et al., 1998. Effects of trophic position and lipid on
organochlorine concentrations in fishes from subarctic lakes in
Yukon Territory. Canadian Journal of Fisheries and Aquatic
Sciences, 55, 869–881.
Kitching, R. L., 2000. Food Webs and Container Habitats.
Cambridge: Cambridge University Press.
Kitching, R. L., 2001. Food webs in phytotelmata: ‘bottom-up’ and
‘top-down’ explanations for community structure. Annual
Review of Entomology, 46, 729–760.
Menge, B. A., and Sutherland, J. P., 1987. Community regulation:
variation in disturbance, competition, and predation in relation
to environmental stress and recruitment. American Naturalist,
130, 730–757.
Moore, J. C., et al., 1993. Influence of productivity on the stability
of real and model ecosystems. Science, 261, 906–908.
Oksanen, L., and Oksanen, T., 2000. The logic and realism of the
hypothesis of exploitation ecosystems. American Naturalist,
155, 703–723.
Oksanen, L., et al., 1996. Structure and dynamics of arctic–
subarctic grazing webs in relation to primary production.
In Polis, G. A., and Winemiller, K. O. (eds.), Food Webs: Integration of Pattern and Process. London: Chapman & Hall,
pp. 231–244.
Pace, M. L., et al., 1999. Trophic cascades revealed in diverse ecosystems. Trends of Ecology and Evolution, 14, 483–488.
Persson, L., 1999. Trophic cascades: abiding heterogeneity and
the trophic level concept at the end of the road. Oikos, 85,
385–397.
Persson, L., et al., 1996. Productivity and consumer regulation –
concepts, patterns, and mechanisms. In Polis, G. A., and
Winemiller, K. O. (eds.), Food Webs: Integration of Pattern
and Process. London: Chapman & Hall, pp. 396–434.
Pimm, S. L., 1982. Food Webs. London: Chapman & Hall.
Post, D. M., et al., 2000. Ecosystem size determines food-chain
length in lakes. Nature, 405, 1047–1049.
Power, M. E., et al., 1996. Disturbance and food chain length in
rivers. In Polis, G. A., and Winemiller, K. O. (eds.), Food Webs:
Integration of Pattern and Process. London: Chapman & Hall,
pp. 286–297.
330
FOOD CHAIN