7923

• UCREFRP Catalog Number: 7923
• Author: Carter, J. G. and V. A. Lamarra.
• Title: An Ecosystem Approach To Environmental Management, Chapter 17.
• USFW Year: n.d.
• USFW - Doc Type: 261-287
• Copyright Material: YES

(heterotrophy) and low photosynthesis (autotrophy).
However, if autotrophy (high primary production) is
greater than heterotrophy, then the ratio will be greater
than 1. Thus, continuous monitoring of production and
respiration rates through the seasons will allow a direct
determination of the balance between primary production
and consumption of organic material. It is this balance
which will be a measure of the relative health of the
system from which departures may be identified and related
to the system structural components. This mechanism of
classifying the White River system is of great importance
in determinimg potential structural or functional changes
in the biotic component in a timely manner.

RATIONALE OF THE ECOSYSTEM APPROACH

Ecosystem resolution can be carried from the most
gross features (macrostructure/function) to the most
miniscule (microstructure/function). What must be kept in
mind with the management/monitoring program, therefore is
a reasonable perspective based on logic, economics,
regulatory requirements, ecosystem knowledge and the
expected pathway or mechanism of effects.

Based on the previous view of the aquatic ecosystem,
we can begin, for example, at the macro-level by
establishing relationships between primary production and
environmental physical factors such as light, temperature,
water chemistry and so forth. For the invertebrate or
consumer populations we can establish relationships
between environmental factors, terrestrial organic input,
primary production, and production of the consumers. At
the decomposer level we can measure indices of microbial
community dynamics such as enzymatic activities coupled to
community metabolism and relate this to stream physical
environment, organic matter and water chemistry.
Overlaying all these subsystems we can determine
production/respiration (P/R) ?nd decomposition rates as
related to environmental factors through the year to
arrive at a temporal, quantitative picture of gross
community behavior.

By considering an ecosystem in terms of energy or
carbon flow, measuring production and consumption between
each subsystem and for the overall system, and calculating
mass balances, we will arrive at a quantitative
description of the ecosystem. This quantitative
description then becomes a statistically based valid
reference with which to compare future system behavior for
determination of departures from normality. If the
relationships under consideration are valid, departures

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