Indicator Species

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TAXON
LATIN NAME / Feature
Kingdom Animalia (Animal, Plant or Fungi - this is an animal)
Phylum Arthropoda (meaning "joint-legged," are invertebrates)
Class
Insecta (insects, 6 jointed legs, head, thorax and abdomen)
Order
Ephemeroptera (mayfly, ephemeral meaning short-lived)
Family Ephemerellidae
Genus Ephemerella
Species Ephemerlla inermis
Freshwater benthic macroinvertebrates comprise only three of the many animal phyla –
Arthopoda, Annelida, and Mollusca. There is a fourth Phylum, Platyhelminthes that has
the Class Turbellaria (flatworms) which we are not addressing here. Almost all of the
freshwater benthic macroinvertebrates you will encounter fall within the taxnomic groups
below.
PHYLUM
Annelida
Arthropoda(crustaceans, insects,
(segmented
spiders, and relatives)
worms)
Mollusca (mollusks)
Malacostraca (crayfish, pill
bugs, shrimp, and relatives)
Hirudinea
(leeches)
Gastropoda
(gastropods, slugs, and
freshwater snails)
Insecta (see Orders below)
Oligochaeta
(aquatic
earthworms)
Bivalvia (bivalves,
mussels and clams)
CLASS
Ephemeroptera (mayflies)
Odonata (dragonflies and
damselflies)
Plecoptera (stoneflies)
Hemiptera (true bugs)
Trichoptera (caddisflies)
Lepidoptera (butterflies and
ORDER
moths)
Coleoptera (beetles)
Megaloptera (alderflies,
dobsonflies, fishflies)
Neuroptera (spongillaflies)
Diptera (two-winged or true
flies)
Why Study the Stream-Bottom Macroinvertebrates?

Stream-bottom macroinvertebrates are an important part of the community
of life found in and around a stream.
Stream-bottom macroinvertebrates are a link in the aquatic food chain. In most
streams, the energy stored by plants is available to animal life either in the form of
leaves that fall in the water or in the form of algae that grows on the stream
bottom. The algae and leaves are eaten by macroinvertebrates. The
macroinvertebrates are a source of energy for larger animals such as fish, which in
turn, are a source of energy for birds, raccoons, watersnakes, and even fishermen.

Stream-bottom macroinvertebrates differ in their sensitivity to water
pollution.
Some stream-bottom macroinvertebrates cannot survive in polluted water. Others
can survive or even thrive in polluted water. In a healthy stream, the streambottom community will include a variety of pollution-sensitive
macroinvertebrates. In an unhealthy stream, there may be only a few types of
nonsensitve macroinvertebrates present.

Stream-bottom macroinvertebrates provide information about the quality of
a stream over long periods of time.
It may be difficult to identify stream pollution with water analysis, which can only
provide information for the time of sampling. Even the presence of fish may not
provide information about a pollution problem because fish can move away to
avoid polluted water and then return when conditions improve. However, most
stream-bottom macroinvertebrates cannot move to avoid pollution. A
macroinvertebrate sample may thus provide information about pollution that is
not present at the time of sample collection.

Stream-bottom macroinvertebrates are relatively easy to collect.
Useful stream-bottom macroinvertebrate data are easy to collect without
expensive equipment. The data obtained by macroinvertebrate sampling can serve
to indicate the need for additional data collection, possibly including water
analysis and fish sampling.
Indicator Species
Biological indicator species are unique environmental indicators as they offer a signal of
the biological condition in a watershed. Using bioindicators as an early warning of
pollution or degradation in an ecosystem can help sustain critical resources. While
indicator species is a term that is often used, it is somewhat inaccurate. Indicators are
actually groups or types of biological resources that can be used to assess environmental
condition. Within each group, individual species can be used to calculate metrics such as
percent Achnanthes minutissima (a diatom species) or groups of species (e.g., EPT taxa)
or individual orders (e.g., Caddisfly larvae - Order Trichoptera) in an effort to assess
water quality conditions.
The major groups include:




Fish
Invertebrates
Periphyton
Macrophytes
Marine environments also utilize biological indicators. While this site focuses
predominately on freshwater resources, marine/tidal indicators are also quite important in
sustaining biodiversity and preserving and restoring marine and estuarine resources.
Macroinvertebrates That Are Sensitive to Pollution
Found in Good Quality Water
Stonefly
Riffle Beetle Adult
Gilled Snail
Planarian
Mayfly
Water Penny
Caddisfly
Hellgramite
Macroinvertebrates That Are Somewhat Sensitive to Pollution
Found in Good or Fair Quality Water
Crayfish
Alderfly
Crane Fly
Riffle Beetle Larva
Damselfly
Sowbug
Dragonfly
Watersnipe Fly
Scud
Whirligig Beetle Larva
Fishfly
Clam or Mussel
Macroinvertebrates That Are Tolerant of Pollution
Found in Any Quality Water
Aquatic Worm
Lunged Snail
Black Fly
Leech
Midge Fly