Mysids (Crustacea : Mysidacea) are ubiquitous members of the permanent,
endemic hyperbenthic fauna of estuarine and other coastal ecosystems. They
often occur in high numbers and their ecological importance, particularly
their role in food chains as a link between the benthic and pelagic systems,
is becoming increasingly apparent. In general, mysids are omnivores, feeding
on detritus, zooplankton and phytoplankton, and they contribute up to
40% of the standing stock of omnivores in some systems. In estuaries,
specific mysid faunas often occur in discrete zones, usually as a result of
different salinity tolerances, although responses to turbidity and water flow
also determine mysid distributions. Many mysids are particularly sensitive to
chemical contaminants as illustrated by their relatively low 96-h
LC50 values. Due to this sensitivity, the United States
Environmental Protection Agency promotes the use of
Americamysis ( Mysidopsis) bahia for laboratory toxicity
testing; however, there is growing interest in the use of local, endemic
species rather than the standard American mysid. At Plymouth, novel and
sensitive techniques are being developed for assessing sublethal responses to
toxicants by use of the northern European estuarine mysid
Neomysis integer. This paper summarizes the ecological
role of mysids in estuaries and describes their potential for use for
estuarine environmental monitoring.