Habitat connectivity and ecosystem productivity: implications from a simple model.

American Naturalist



The import of resources (food, nutrients) sustains biological production and food webs in resource-limited habitats. Resource export from donor habitats subsidizes production in recipient habitats, but the ecosystem-scale consequences of resource translocation are generally unknown. Here, I use a nutrient-phytoplankton-zooplankton model to show how dispersive connectivity between a shallow autotrophic habitat and a deep heterotrophic pelagic habitat can amplify overall system production in metazoan food webs. This result derives from the finite capacity of suspension feeders to capture and assimilate food particles: excess primary production in closed autotrophic habitats cannot be assimilated by consumers; however, if excess phytoplankton production is exported to food-limited heterotrophic habitats, it can be assimilated by zooplankton to support additional secondary production. Transport of regenerated nutrients from heterotrophic to autotrophic habitats sustains higher system primary production. These simulation results imply that the ecosystem-scale efficiency of nutrient transformation into metazoan biomass can be constrained by the rate of resource exchange across habitats and that it is optimized when the transport rate matches the growth rate of primary producers. Slower transport (i.e., reduced connectivity) leads to nutrient limitation of primary production in autotrophic habitats and food limitation of secondary production in heterotrophic habitats. Habitat fragmentation can therefore impose energetic constraints on the carrying capacity of aquatic ecosystems. The outcomes of ecosystem restoration through habitat creation will be determined by both functions provided by newly created aquatic habitats and the rates of hydraulic connectivity between them.

Publication type Article
Publication Subtype Journal Article
Title Habitat connectivity and ecosystem productivity: implications from a simple model.
Series title American Naturalist
DOI 10.1086/510258
Volume 169
Issue 1
Year Published 2007
Language English
Contributing office(s) San Francisco Bay-Delta, Toxic Substances Hydrology Program, Pacific Regional Director's Office
Description 13 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title American Naturalist
First page E22
Last page E33
Online Only (Y/N) N
Additional Online Files (Y/N) N
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