WMOD00423

• Title: Currents…Developing Technology for Tomorrow's Challenges
• Date: 1/1/1993
• Weather Modification - Doc Type: Report

Humans have used other living organ-
isms for many years to monitor life support
systems. One of the best known examples,
the caged canary in the mine, served as an
advance warning of trouble to miners. An

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Bioassays, using single species test or-
ganisms, are also used to detect effects of
toxicants which may exist in the water.
Standard toxicity test methodologies exist
for Daphnids (water fleas) such as

Biosurveys and
Bioassays -
Sentinels of the
Environment

S. MARK NELSON and RICHARD A. ROLlNE
Applied Sciences Branch

extreme sensitivity to toxic gases caused
the canary to experience distress sooner
than its human companions.
Reclamation presently uses biological
data in much the same way to monitor con-
ditions in some of its water resources.
Biomonitoring of waters can include both
field and laboratory studies-biosurveys
and bioassays. During a biosurvey, organ-
isms are collected (usually aquatic macro-
invertebrates, but sometimes fishes) from
the environment. Analyzing these biologi-
cal communities allows for detection of
environmental impairment. Recent devel-
opments by the EP A (Environmental
Protection Agency) in this area have
allowed for greater ease in the presentation
of these types of data. Rather than report a
confusing list of scientific names, new
techniques now summarize this informa-
tion into a single number which cor-
responds to a stream condition.

C eriodaphnia dubia and the fathead min-
now Pimephales promelas. Test end points
range from mortality in acute tests
(~ days in length) to number of young
produced and growth in chronic tests
(>4 days in length).
Biosurveys and bioassays are used to
detect impairment and toxicity, respec-
tively. They do not, however, provide
direct information on the cause of impair-
ment or toxicity. This additional infor-
mation requires physical habitat measure-
ments and chemical sampling. In the case
of toxicants, chemical sampling cannot be
relied on solely because only living organ-
isms integrate the dynamics of the
chemical, physical, and biological world
that they inhabit. In many cases in the past,
chemical water quality standards have
underprotected the environment. This
underprotection occurred because the
standards did not account for the effects of
combinations of toxicants or the effects of
the environment (e.g., pH, buffering capac-
ity, and dissolved oxygen shifts) on the
toxicants.