Guide to Pacific Northwest Macroinvertebrate Monitoring and Identification
Jeff Adams
with Mace Vaughan and Scott Hoffman Black - The Xerces Society (www.xerces.org)
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- the Minnesota Pollution Control Agency has a really nice, detailed glossary of watershed and monitoring terms: http://www.pca.state.mn.us/gloss/index.shtml
- for a more complete glossary of terms used in identification, you can purchase a ring bound glossary from Mindy Allen, a Northwest taxonomist; or go on-line to the glossary of the North Dakota aquatic insect key (http://www.waterbugkey.vcsu.edu/php/glossary.php), the Lander University glossary of Invertebrate Anatomy (http://www.lander.edu/rsfox/310glossaryLab.html), the Earthlife Web Glossary of Entomological Terminology (http://www.earthlife.net/insects/six.html), or a large multilingual site by the European Environmental Agency (http://glossary.eea.eu.int/EEAGlossary/).
anterior - toward the front end;
either in reference to part of an entire organism (anterior end of a mayfly
= head end) or to a 
particular
body part (anterior edge of head = that part of the head that is farthest
from the tails)
anal gills - fleshy, finger-like gills that at at the on the last segment of the abdomen (see image)
anal prolegs - an extra pair of legs or hooks at the end of the abdomen that act as extra appendages during the larval stages, but are absent in adults
B-IBI - the Benthic Index of Biological Integrity is an analysis tool that uses characteristics of the macroinvertebrate community that respond predictably to changes in human influence in the watershed, to develop scoring criteria for evaluating the biological condition of a waterbody; these characteristics may include total taxa richness (the number of different kinds of macros found in a sample), stonefly richness, dominance of a particular taxon, and percent of the community that is tolerant to pollution
benthic - associated with the bottom or substrate of a waterbody. To be benthic, an organisms must spend the majority of its time on or between the rocks, mud, sand, or other substrate in moving or still water. Most macros are benthic for only part of their life cycle.
biological assessment - using living things to evaluate the effects of human activities
biological condition - describes the ability of a waterbody to support a diverse and healthy biological community (fish, macroinvertebrates, algae, plants) that is similar to what the waterbody would have supported before Europeans arrived in the Northwest
biota - a single term to describe the collection of species of plants and animals that are living in a particular habitat (e.g. freshwater biota includes fish, amphibians, invertebrates, algae, and other plants)
BLM - Bureau of Land Management http://www.blm.gov/nhp/index.htm; a division of the Department of the Interior and an important Northwest land manager, particularly in Oregon
CA DFG - CAlifornia Department
of Fish and Game http://www.dfg.ca.gov/;
the department generally in charge of biological assessment efforts in
California
cerci - the segmented "tails" of mayflies and stoneflies (see images); two helpful rules - all stoneflies have two cerci, and if the insect has 3 cerci, it must be a mayfly even though some common mayflies only have 2; beetles, dragon and damselflies, and other insects may also have cerci, but they aren't as prominent as in the mayflies and stoneflies
denticle - bumps or teeth that are sometimes found on various macroinvertebrate body parts
detritus - pieces of organic material or debris in the water column or accumulated on the substrate
dorsal
- top (left side of image, the right side is a lateral view); on most
animals it's the part of the animal that we would call the "back"
dorsoventrally - top to bottom, usually in reference to being flattened from top to bottom, like a flatheaded mayfly, a sowbug, or a water penny (see image)
ecoregion - areas where the geology, vegetation, land use, and topography are similar, and where similar groups of organisms might be expected to live
elytra - the hard top wings of adult beetles
eutrophic - waterbody with high nutrient content and high plant productivity; usually further characterized by low oxygen at certain times of year
family
- a group of related genera and species; e.g., The family Rhyacophilidae
includes only two genera, but dozens of species.
femora (or femur) - usually the largest segment of the leg (see images); typically the first noticeable segment from the body, but as with caddisflies (image on right) other segments near the body may be well developed and the femur will be the third segment (but still the largest)
filamentous
- thin and threadlike; usually in reference to fine algae that is made
of of long strings of cells (see image, to the right of the nematode)
genus - a group of related species of plants and animals; generally, the second most detailed level; usually, the macroinvertebrate species in a genus look very similar, and can sometimes be difficult to tell apart. Many of the standard levels of identification stop at the genus level.
gradient - also known as slope; the steepness of a streambed that influences water velocity and substrate size
hard bottomed - a water body that has a rocky or hard substrate (usually gravel, cobbles, boulders, or bedrock) for macroinvertebrates to cling to or crawl over
HBI - the Hilsenhof Biotic Index is an index of a macroinvertebrate's sensitivity to organic enrichment that typically occurs as a result of excessive nutrient inputs. Index values for individual taxa range from 1 to 10. Low scores indicate high sensitivity (found only in waters with low organic enrichment). High scores indicate low sensitivity (tolerant of waters with high organic enrichment). HBI index values for each taxa are listed in the taxa list for Oregon streams in Appendix F of the Oregon Plan's Water Quality Monitoring Guidebook.
ID DEQ - Idaho Department of Environmental Quality; generally referring to the biological components of the water quality program http://www2.state.id.us/deq/water/water1.htm
labrum - the "lip" at the front of insect's head (see images)
lacinia
- insect mouthpart that is the end of the maxillae and, along with the
mandibles, is helpful in the identification of some insects, particularly
the stonefly family Perlodidae
larva (larvae) - the immature stage of most invertebrates that is distinctly different than the egg that it hatched from and the adult that it will eventually become
lateral
- referring to the side (see right side of image, left side is dorsal
view); equivalent in humans is our profile
lentic - having to do with lakes or standing water
lotic - having to do with streams or rivers; moving water
macroinvertebrate - describes "large"
animals without backbones. Freshwater macroinvertebrates includes all
aquatic insect larvae (with a few pupae and adults) and other aquatic
invertebrates (worms, snails, clams, leeches, crayfish, etc.) that are
larger than 500 micrometers (µm) = only 1/2 millimeter (mm) = about
half the thickness of a dime. The largest of the freshwater macroinvertebrates
in North America are the mussels and crayfish, but even those are not
much larger than your hand. Among aquatic invertebrates, however, even
the 500 µm size macroinvertebrates are large when compared to the
vast world of microcrustaceans and other meiofauna that rarely grow larger
than a 
couple
hundred micrometers in length(that's about the thickness of a human hair!).
mandible - the chewing mouthpart of many insects (see images); particularly prominent in predators
maxillae - major mouthparts of the head that are behind the mandibles; sometimes very prominent as in many stoneflies (see lacinia above; the entire mouthpart that the lacinia is attached to is called the maxillae)
maxillary palps - 
a
finger-like appendage on the maxillae; important in the identification
of some mayflies
mesonotum - the top of the middle (of three) thoracic segment (see image)
metanotum - the top of the last (of three) thoracic segment (see image), the segment furthest from the head
metric - a characteristic of an assemblage of organisms (in this case macroinvertebrates) that responds predictably to changes in human disturbance
multimetric index - an analysis tool that uses graphical interpretation of predictable biological responses to human disturbance to evaluate the level of human impact on a particular habitat (see also B-IBI)
multivariate model - a statistical model that allows you to analyze and interpret complex data sets, which include many independent and possible dependent variables that correlate to each other to varying degrees (see also WOWSA)
Northwest (Pacific Northwest, NW) - the region covered by this Guide is called the Northwest or Pacific Northwest and abbreviated NW throughout the Guide; the region includes the states of Washington, Oregon, and Idaho in their entirety and includes western Montana, southern British Columbia, and Northern California; much of the material may also apply to northern Utah and Nevada, and western Wyoming.
nymph - describes the larvae of several aquatic insect orders that don't have a pupal stage during their metamorphosis; the best known include mayflies, stoneflies, and dragonflies
oligotrophic
- a water body that is nutrient poor, oxygen rich, and has only modest
algal and plant communities
operculate - describes something that covers other things; e.g., operculate gills (see image) are large gills that cover the remaining gills
operculum
- plate or lid that covers other body parts; fish have an operculum covering
their gills; some beetles have one covering their hind end; and many snails
have an operculum that covers their opening when they withdraw into their
shell (see image)
order - a group of related families, genera, and species
OR DEQ - ORegon Department of Environmental Quality; generally refers to the biological division of the water quality program http://www.deq.state.or.us/wq/
Oregon Plan Guidebook - refers to the Oregon Plan for Salmon and Watersheds Water Quality Monitoring Guidebook
Pacific Northwest (Northwest, NW) - the region covered by this Guide is called the Northwest or Pacific Northwest and abbreviated NW throughout the Guide. The region includes the states of Washington, Oregon, and Idaho in their entirety and includes western Montana, southern British Columbia, and Northern California; much of the material may also apply to northern Utah and Nevada, and western Wyoming.
percent impervious area - the percentage of a watershed that rain can't soak into. You can also think of it as the portion of the watershed that is covered with roads, rooftops, and parking lots. Percent impervious area can be used as a rough estimate of human influence in developing B-IBI's for urban and urbanizing watersheds.
posterior
- toward the rear end; either in reference to part of an entire organism
(posterior end of a mayfly = tail end) or to a particular body part (posterior
edge of abdomen = the part of the abdomen farthest from the head)
prementum - the grabbing part of the modified labium of dragon and damselflies (see image)
pronotum
- the top of the first (of three) thoracic segment in aquatic insects;
top of the the segment closest to the head (see images)
reference conditions - the chemical, physical, and biological characteristics that you could expect a stream to be have in the absence of human influences in the watershed. Since no watershed is completely lacking in human influence, reference conditions are usually represented by the least disturbed streams in an area.
reference sites - streams with watersheds that are the most similar to a pre-European state and have been the least affected by human activities.
richness - the number of different kinds of things (typically in reference to richness of macroinvertebrate taxa
riffles - sections of streams where the stream is steeper and narrower; the water is shallower and rougher (often with white bubbles); and the substrate is larger (typically gravel and cobble, sometimes with boulders)
sclerotized - hardened; most aquatic insects have some sclerotization; riffle beetle larvae, for example, are almost entirely sclerotized, while midges only have a sclerotized head capsule (see images)
scutellum
- small triangular plate between the front edges of the hard top
wings (elytra) of many beetles (see image)
species - the lowest level of identification; the name given to the group of organisms that can produce viable offspring. Subspecies, breeds, and varieties are often used as even lower levels of identification, but the different subspecies can usually create offspring - think of dogs, they're all one species and can interbreed, but they can look dramatically different, so we call the different kinds breeds
stenotherm - requires a limited range of water temperatures to survive; for example, a cold water stenotherm will only be found regularly in cold, often spring or groundwater fed streams and rivers
substrate - the mineral (e.g. rocks and silt) and organic (e.g. woody debris and leaves) materials that comprise the stream bottom and provide habitat for benthic macroinvertebrates
tarsus - (plural = tarsi) the outer segment of an insects leg just before the claw
taxon - (plural = taxa) generic term used to describe a group of organisms that share characteristics that make them similar on some level. The taxon with the broadest similarities is the species (e.g., Zapada oregonensis); other examples of a taxon include genus (Zapada), family (Nemouridae), and order (Plecoptera).
taxonomy
- the science of identifying organisms; assigning names and relationships
related to the hierarchy of all life
tubercles - bumps or spikes on the exoskeleton; particularly prevalent in the mayfly family Ephemerellidae (see images to right)
USDA FS - the Forest Service http://www.fs.fed.us/; a division of the US Department of Agriculture and an important land manager in the Northwest
US FWS - the United States Fish and Wildlife Service http://www.fws.gov; a division of the US Department of the Interior; the agency responsible for managing freshwater and terrestrial endangered species and a number of National Wildlife Refuges across the Northwest
ventral
- bottom or underside; equivalent in humans would be our stomach
ventral apotome - the plate on the underside of a caddisfly's head that separates the two major sides of the head capsule and is can be very helpful in identifying many caddisflies. The ventral apotome may separate the two sides entirely or it may only be present as a small wedge at the top or the bottom of the line where the two sides meet (see images).
voltinism - the number of life cycles completed by a taxon in a 12 month period; for example, if an egg is laid in January then hatches, grows, emerges as an adult, and lays eggs and dies in the following January, then the taxon has gone through 1 generation in a year and is considered univoltine; bivoltine = 2 generations/year; multivoltine = more than 2 generations/year (used in this Guide to describe more than 1 generation/year); and semivoltine = more than 1 year /generation (additional voltinism information).
WA DOE - WAshington State Department Of Ecology's stream biological monitoring division http://www.ecy.wa.gov/programs/eap/fw_benth/fwb_intr.html
WOWSA - the Western Oregon and Washington Stream Assessment model has been developed by faculty and students at Utah State University. WOWSA is a multivariate model that uses a large database of reference streams in the western Pacific Northwest to predict what macroinvertebrates would be expected in any stream with an identified set of physical habitat characteristics. The output includes, a number that reflects what was observed in the test stream relative to what was expected by the model; other output includes lists of macroinvertebrates that were expected but not seen and those that were seen but not expected.
mesosternal Y - a Y-shaped characteristic between the legs on the underside of the middle thoracic segment of many stoneflies; particularly helpful in identifying Perlodidae stoneflies, but is often not very clear in immature or damaged specimens
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