Aquatic-terrestrial subsidies | Wikipedia audio article


Energy and nutrients derived from aquatic
ecosystems and transferred to terrestrial ecosystems are termed aquatic-terrestrial
subsidies or, more simply, aquatic subsidies. The most common examples of aquatic subsidies
involve organisms that move across habitat boundaries and deposit their nutrients as
they decompose in terrestrial habitats or are consumed by terrestrial predators, such
as spiders, lizards, birds, and bats. This phenomenon is exemplified by aquatic
insects that develop within streams and lakes before emerging as winged adults and moving
to terrestrial habitats. Fish removed from aquatic ecosystems by terrestrial
predators are another important example. Conversely, the flow of energy and nutrients
from terrestrial ecosystems to aquatic ecosystems are considered terrestrial subsidies; both
aquatic subsidies and terrestrial subsidies are types of cross-boundary subsidies.==Ecological importance of aquatic subsidies
==While the magnitude of aquatic subsidies to
terrestrial ecosystems is low compared to those moving in the reverse direction (from
terrestrial to aquatic habitats), aquatic subsidies are generally of higher nutritional
quality because they come from animal, rather than plant-based or detrital, sources. In addition to their nutritional value, however,
aquatic subsidies are increasingly recognized as important sources of environmental contaminants
to terrestrial food webs. In this way, aquatic animals can accumulate
pollutants in their tissues and exoskeletons (such as metals and polychlorinated biphenyls)
and move them to riparian and terrestrial systems as they emerge or are consumed by
terrestrial predators.==Measuring aquatic-terrestrial connections
==Researchers use several tools to assess how
terrestrial and aquatic food webs are connected. Stable isotopes, particularly of carbon, nitrogen,
hydrogen, and oxygen, can be used to determine what resources consumers are eating . Other
compounds, such as fatty acids, can also be used to trace food web connections between
aquatic and terrestrial ecosystems .==
See also==Ecology portal
Environment portal

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