Rare Aquatic Insects, Or How Valuable Are Bugs? Richard W

Great Basin Naturalist Memoirs Volume 3 The Endangered Species: A Symposium Article 8 12-1-1979 Rare aquatic insects, or how valuable are bugs? Richard W. Baumann Monte L. Bean Life Science Museum and Department of Zoology, Brigham Young University, Provo, Utah 84602 Follow this and additional works at: https://scholarsarchive.byu.edu/gbnm Recommended Citation Baumann, Richard W. (1979) "Rare aquatic insects, or how valuable are bugs?," Great Basin Naturalist Memoirs: Vol. 3 , Article 8. Available at: https://scholarsarchive.byu.edu/gbnm/vol3/iss1/8 This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist Memoirs by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. RARE AQUATIC INSECTS, OR HOW VALUABLE ARE BUGS? Richard W. Bauinann' Abstract.— Insects are an important element in the analysis of aquatic ecosystems, (1) because the limited dispersal abilities of many aquatic species means that they must make a living under existing conditions, and (2) because they are often sensitive to slight changes in water and stream quality, thus making excellent indicators of the physical and chemical conditions in a system. Examples of rare, ecologically sensitive species are presented from the Plecoptera, Ephemeroptera, and Trichoptera. Detailed studies of rare aquatic insect species should produce important information on critical habitats that will be useful in the protection of endangered and threatened species in other groups of animals and plants. I use the term rare instead of endangered the distribution patterns of certain species fit or threatened, because no aquatic insects are nicely with a model of island biogeography. presently on the United States hst of endan- Many stoneflies (Plecoptera) are mostly re- gered fauna. The term is still relative, stricted to pristine habitats characterized by though, because my experience indicates that cold, clean continuously flowing streams at nearly every species can be plentiful if high elevations or in special spring-fed habi- sought at the right place at the right time. tats. It thus follows that if the particular hab- Aquatic insects are useful to anyone study- itat in which they occur is threatened, then ing aquatic habitats because they usually they almost automatically become rare and meet two criteria that are essential in assess- may become extinct. Such species popu- ing aquatic systems. First, they often have lations are often considered relicts of faunas very limited dispersal abilities, which means that were once more prevalent when more that they must stay and make a living under ideal conditions occurred. existing conditions. Second, they are often Studies on the stonefly genus Amphine- sensitive to slight changes in water quality, so mura (Baumann and Gaufin 1972, Bauman their presence or absence tells something 1976) showed that it was a Palearctic genus about the physical and chemical conditions in that had extended into the Neotropical the system. Realm and was still present in western North Because the conditions present in a given America in limited relictual populations. Al- habitat determine which species can live though four species showed fairly wide distri- there, these organisms become living in- bution patterns in the United States and Mex- dicators of water quality in aquatic ecosys- ico, three species were restricted to a single tems. If these organisms are invertebrates mountain range. Amphinemura apache oc- which exist at low levels in the food web, this curred in the Chiricahua Mountains of Ari- is an advantage. Invertebrates are easier to zona, A. reinerti, was limited to Sierra Potosi, study than are larger animals, because they Mexico, and A. piiehhi was found in a moun- are more abundant and usually do not carry tain drainage near Veracruz, Mexico. the emotional stigma associated with large These A7nphinemiira species are poor fliers vertebrates. They can also indicate adverse and almost need a water connection for dis- habitat problems sooner, so that adjustments persal. They live only in small streams that can be made in water or stream quality be- flow all year around and are of high quality. fore the top carnivores are severely affected. Their distribution patterns closely follow the During my studies of aquatic insects in spruce-fir and high pine forests in the south- western North America, I have found that western United States and Mexico. They are 'Monte L. Bean Life Science Museum and Department of Zoology, Brigham Young University, Prove, Utah 84602. 65 66 Great Basin Naturalist Memoirs No. 3 thus good indicators of a special aquatic habi- esting examples and their special habitat re- tat in western North America. quirements are: Goriella baiimanni, organic Another example of restricted distribution ooze in spring seeps; Psychronia costalis, in the stoneflies is Capnia lacustra Jewett, small meadow streams above 8,000 feet; Des- which only occurs in Lake Tahoe. It carries mona bethida, small spring streams. on its entire life cycle under water at depths The number of rare aquatic insects is quite of 100-400 feet (Jewett 1963, 1965). Only large because of the number of different one other similar stonefly is known, and that aquatic habitats available and the ability of is the genus Baikaloperia (Zapekina-Dulkeit insects to fit into relatively small niches with- and Zhiltzova 1973), in Lake Baikal, Siberia. in those habitats. This is actually a positive It is also wingless and possesses similar mor- value, however, because it allows the re- phological and ecological traits. It is not sur- searcher to more closely understand the eco- prising that these two deep, ancient lakes system since it can be divided into smaller contain similar rare species which evolved parts. under specialized conditions and will be lost Two final examples of rare insects that if their habitat is destroyed. have very specific habitat requirements are Much attention has been given to several the met-winged midges and the water penny fish species that occur in the Colorado River beetles. drainage such as the Humpback Chub, Ra- Net-winged midges are flies which have zorback Sucker, and Colorado River Squaw- become adapted to living in torrenticolus fish. These fish developed through time in habitats. The larvae are greatly modified into another type of specialized habitat that ex- chitonlike organisms that attach themselves cluded the salmonids and allowed other taxa to the substrate by sucking discs. They live to radiate into the open niches. Invertebrate only in clean, cold, well-aerated waters species have also developed imder similar which have a stable, smooth-grained sub- conditions and several forms also occur in the strate. Thus they can be excellent indicators Colorado River drainage. Edmunds (1976) of these habitat conditions that occur at falls lists several mayfly species which are rare and quick-flowing mountain torrents. Hogue and restricted to the Colorado River drainage (1973) lists several Blephariceridae species and similar large warm rivers in western that are presently known only from a single North America. locality or mountain range. This is not simply The following are a few examples of rare an artifact of incomplete collecting, but a re- mayfly species and an indication of where sult of poor adult dispersal ability plus the they occur in the United States: Analetris very specialized habitat requirements of the eximia. Green River; Lachlonia saskotchewa- larvae noted earlier. nensis. Green, Colorado, and White Rivers; Water penny beetles have an adult stage Anepeorus rusticus. Green River; Home- tliat looks like a terrestrial beetle but a larval oneuria sp. Escalante and Colorado Rivers. stage that is highly modifed for life on the These invertebrate species provide additional bottom of streams. The larva is greatly flat- evidence that our large, warm, western rivers tened so that the head and appendages are contain animal species that have adapted to completely hidden under the thoracic and special conditions critical for their survival. abdominal sclerites. The single eastern spe- Caddisflies or the Trichoptera are inter- cies Psephenus herricki is rather widely dis- esting insects that occur in a wide variety of tributed, but the five known western species aquatic habitats. Most are good fliers and dis- have very restricted distributions (Brown and tribute freely, but many species are restricted Murvosh 1974). Two species, P. montanus to a certain habitat because of the larval re- (White Mountains, Arizona) and P. arizo- quirements. nensis (Chiricahua Mountains, Arizona) have Wiggins (1977) published an outstanding very limited areas of occurrence. An inter- distri- work that makes it possible for any trained esting note is that this type of limited biologist to classify caddisfly larvae to genus. bution pattern is also exhibited by several Thus it provides another tool for evaluating species in the Plecoptera, Trichoptera, and habitats using aquatic insects. A few inter- Ephemeroptera. 1979 The Endangered Species: A Symposium 67 Many more examples of "rare" aquatic in- should place renewed emphasis on studies of sects could be given which probably fit into them. We must, however, be aware of the the endangered or threatened categories as fact that people in general do not imderstand presently understood. They are exciting to the scientific value of insects and might react me for pure scientific studies of zoogeo- poorly to "bugs" being used to justify the graphy and phylogeny. However, I feel that preservation and conservation of special eco- the real value is not simply to say "I found systems. However, scientific investigations of another rare creature," but instead to make high quality must utilize all possible avenues us more sensitive about the critical habitat of investigation if problems are to be solved conditions which produced these rare species. with a minimum expenditure of time, effort, Insects tend to be more abundant and are and resources.

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