The sustainability of aquatic ecosystems can best be
ensured with a variable flow regime, adequate sediment
and organic matter inputs, natural fluctuations in heat
and light, clean water, and a naturally diverse biotic
community. Failure to provide for these natural requirements
results in loss of species and ecosystem
services in wetlands, rivers, and lakes. Aquatic ecosystems
can be protected or restored by recognizing
the following:
1) Aquatic ecosystems are connected strongly to terrestrial
environments, rather than isolated bodies
or conduits. Further, aquatic ecosystems are connected
to each other.
2) Dynamic patterns of flow that are maintained
within the historical range of variation will promote
the integrity and sustainability of freshwater
aquatic systems.
3) Aquatic ecosystems additionally require sediments,
thermal and light properties, chemical and
nutrient inputs, and biotic populations to fluctuate
within natural ranges, neither experiencing excessive
excursions from their historical ranges,
nor being held at constant, and therefore unnatural,
levels.
It is one thing to state the requirements for maintaining
aquatic-ecosystem integrity. It is another to enact
these concepts in the context of today’s complicated
society. U.S. water policy currently supports increased
exploitation of water supplies in order to meet demand,
and maintenance of water quality and flow primarily
as they relate to human health (Gleick 1998). But the
age of ever-increasing exploitation is over. We must
redefine water use based on a finite supply and inclusion
of freshwater ecosystem needs (Postel 2000). For
these reasons we offer the following recommendations
for how water is viewed and managed:
1. Incorporate freshwater ecosystem needs, particularly
variable flow regimes, into national and regional
water management policies, along with water quality
and quantity.—The dialog that will bring about a
change in water policies can succeed if conducted in
a nonconfrontational manner. It must be based on mutual
The sustainability of aquatic ecosystems can best beensured with a variable flow regime, adequate sedimentand organic matter inputs, natural fluctuations in heatand light, clean water, and a naturally diverse bioticcommunity. Failure to provide for these natural requirementsresults in loss of species and ecosystemservices in wetlands, rivers, and lakes. Aquatic ecosystemscan be protected or restored by recognizingthe following:1) Aquatic ecosystems are connected strongly to terrestrialenvironments, rather than isolated bodiesor conduits. Further, aquatic ecosystems are connectedto each other.2) Dynamic patterns of flow that are maintainedwithin the historical range of variation will promotethe integrity and sustainability of freshwateraquatic systems.3) Aquatic ecosystems additionally require sediments,thermal and light properties, chemical andnutrient inputs, and biotic populations to fluctuatewithin natural ranges, neither experiencing excessiveexcursions from their historical ranges,nor being held at constant, and therefore unnatural,levels.It is one thing to state the requirements for maintainingaquatic-ecosystem integrity. It is another to enactthese concepts in the context of today’s complicatedsociety. U.S. water policy currently supports increasedexploitation of water supplies in order to meet demand,and maintenance of water quality and flow primarilyas they relate to human health (Gleick 1998). But theage of ever-increasing exploitation is over. We mustredefine water use based on a finite supply and inclusionof freshwater ecosystem needs (Postel 2000). Forthese reasons we offer the following recommendationsfor how water is viewed and managed:1. Incorporate freshwater ecosystem needs, particularlyvariable flow regimes, into national and regionalwater management policies, along with water qualityand quantity.—The dialog that will bring about achange in water policies can succeed if conducted ina nonconfrontational manner. It must be based on mutual
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