Ephemeroptera: Baetidae of Gunnison County, ColoradoIntroduction to Baetis
Small Minnow Mayflies, Blue-winged Olive, BWO, Dark Blue QuillLeach 1815
Updated 21 July 2008
Provisional Species List
Introduction
The Baetis nymphs on the right were living in the Gunnison River near McCabe Lane in March of 2007.
Baetis nymphs earn the name "small minnow mayflies" because they swim like a small fish. They are streamlined for agility swimming and drifting in a current. Most are dark brown or black colored as nymphs. Some have white or reddish colors that help identify them as larvae or adults. The adults have blue or clear wings. They are small and delicate relative to other mayflies such as the Flat-headed (Heptageniidae) or Spiny Crawler (Ephemerellidae) at all ages. The photo below is of a recently emerged Baetis subimago photographed in the Cement Creek drainage in July of 2008. You can see the nymphal exuvia or shuck to the right of the subimago.
Notes
The common species; Baetis bicaudatus, Baetis flavistriga, and Baetis tricaudatus were named in the early part of the 20th century. The less common species were named in last 20 years of the century. Baetis taxonomy changed a lot in the 1990s. Many animals are very difficult to identify even with a microscope. More work on various cryptic or high altitude species is continuing today, driven by interest from many top notch taxonomists and the use of genetic analyses. See references and the other species below. You need adults or mature larvae with brown or black colored wing pads to tell these species apart.
Links
On this website:
Key to Baetis larvae
Baetidae Introduction
These species used to be included in Baetis, but have been assigned to different genera recently: Acentrella insignificans,
Diphetor hageni,
Plauditus virilis
Other websites:
References
Allan,JD 1987 Macroinvertebrate drift in a Rocky Mountain stream. Hydrobiologia 144, 261-268.
Based at the Rocky Mountain Biological Lab in Gothic, the author studied Cement Creek in Gunnison County during the spring, summer and fall of 1975-1978. He found that drift densities (number of animals per 100 m³) were 10 times higher at night. 24 hour totals approached 2000 animals/m³ in mid-summer down to 500 animals/m³ in the fall. Quote from the abstract: "Ephemeroptera, especially Baetis, dominated the drift." He found that benthic density (number of animals/m² from streambed samples) was the best predictor of 24hr drift rate for Baetis bicaudatus. Adding discharge to the calculation (a stepwise regression) helped predict the number of B. bicaudatus in the drift.
Cain,DJ; Luoma,SN; Wallace,WG 2004 Linking metal bioaccumulation of aquatic insects to their distribution patterns in a mining-impacted river. Environmental Toxicology and Chemistry 23, 1463-1473.
Ball,SL; Hebert,PDN; Burian,SK; Webb,JM 2005 Biological identification of mayflies (Ephemeroptera) using DNA barcodes. Journal of the North American Benthological Society 24 3, 508-524.
Clements,WH; Kiffney,PM 1994b Integrated laboratory and field approach for assessing impacts of heavy metals at the Arkansas River, Colorado. Environmental Toxicology and Chemistry 13, 397-404. Abstract
In contrast to Clements research on the Clinch River in Virginia, this study of the Arkansas River near Leadville, Colorado found no change in the total numbers of aquatic insects above and below the Superfund site California Gulch. They did however note a shift in community structure as metal tolerant taxa (Orthocladiinae midges) replaced intolerant taxa (mayflies). "Benthic communities [below California Gulch] were were dominated by Orthocladiinae chironomids."
They ran chronic toxicity tests with Ceriodaphnia dubia and found significantly lower reproduction in water from the site 6 kilometers below California Gulch in the spring. In the fall the sites above California Gulch and the recovery site 45 km below had significantly worse reproduction.
Studying the concentrations of a few heavy metals in water from the Arkansas River they found: "Considerable seasonal variation in metal concentrations was observed at stations downstream from California Gulch. Levels of Cd, Cu and Zn were 7 to 9 times higher at [the station below California Gulch] in spring than in fall and remained elevated at [the recovery station 45 km below] in spring."
They also looked at bioaccumulation of Cadmium (Cd) Copper (Cu) and Zinc (Zn) in algae and the aquatic macroinvertebrates Baetis spp, Arctopsyche grandis and Rhyacophila in fall and spring. They found lots of variation as always but Baetis metal concentrations were usually higher than the other taxa studied. "Levels of Cd, Cu and Zn in periphyton and benthic macroinvertebrates were significantly elevated at stations downstream from California Gulch in both seasons. "
Courtney,LA and Clements,WH 2000 Sensitivity to acidic pH in benthic invertebrate assemblages with different histories of exposure to metals. Journal of the North American Benthological Society 19 (1) 112–127.Abstract
Dodds,GS 1923 Mayflies from Colorado: descriptions of certain species and notes on others. Transactions of American Entomological Society 69, 93-116.
Dodds described Baetis bicaudatus and Baetis tricaudatus, among other mayfly species in this publication. Quote from page 109 regarding the genus Baetis: "This genus is a difficult one with which to deal. The insects are small and the species hard to distinguish. Characteristics based on coloration seem to be of no use whatever where alcoholic specimens must be used. Other characteristics must be relied upon, preferably structural differences large enough to be readily seen and not subject to great variation. Accordingly in the following notes there are described only a few points, for the imago, chief among them, size, peculiarities of hind wing and male forceps. The nymph is equally difficult, with the added uncertainty of change due to age and phase of molting cycle. Here, the characters that seem to give most useful distinctive characters are size of mature nymph, number and length of cerci, size and form of gill lamellae. The color pattern persists fairly well for a while in alcohol (i.e. arrangement of light and dark areas) and has given confirming evidence. In case of both nymphs and imagos, however, there is no high degree of certainty as to the accuracy of specific lines - the group one calls a species may include more than one species or he may have divided a species by the use of variable characters."
Durfee,R; Kondratieff,BC 1993 Description of adults of Baetis magnus (Ephemeroptera: Baetidae). Entomological News 104 5, 227-232.
Hughes,JM; Mather,PB; Hillyer,M; Cleary,C; Peckarsky,B 2003 Genetic structure in a montane mayfly Baetis bicaudatus (Ephemeroptera: Baetidae), from the Rocky Mountains, Colorado. Freshwater Biology 48, 2149-2162.
Jacob,U 2003 Baetis Leach 1815, sensu stricto or sensu lato. A contribution to the genus concept based on species groups with identification keys. Lauterbornia 47: 59-129. [In German, English summary]
Kiffney,PM; Clements,WH 1993 Bioaccumulation of heavy metals by benthic invertebrates at the Arkansas River, Colorado. Environmental Toxicology and Chemistry 12, 1507-1517.
Leach WE. 1815 Entomology. Brewster's Edinburgh Encyclopaedia 9:57-172.
Describes the genus Baetis for the first time.
Lugo-Ortiz,CR; McCafferty,WP 1998 A new North American genus of Baetidae (Ephemeroptera) and key to Baetis complex genera. Entomological News 109 5, 345-353.
McCafferty,WP 1997 Name adjustments and a new synonym for North American Ephemeroptera species. Entomological News 108 4, 318, 320.
McCafferty,WP; Durfee,RS; Kondratieff,BC 1993 Colorado mayflies (Ephemeroptera): an annotated inventory. Southwestern Naturalist 38 3, 252-274.
McCafferty,WP; Waltz,RD 1990 Revisionary synopsis of the Baetidae (Ephemeroptera) of North and Central America. Transactions of American Entomological Society 116, 769-799.
McIntosh,AR; Peckarsky,BL and Taylor,BW 2004. Predator-induced resource heterogeneity in a stream food web. Ecology 85(8) 2279–2290. Abstract
Meyer,MD; McCafferty,WP 2001 Hagen's small minnow mayfly (Ephemeroptera: Baetidae) in North America. Entomological News 112 4, 255-263.
Monaghan, Michael T. , Spaak, Piet , Robinson, Christopher T. & Ward, J. V. 2001 Genetic differentiation of Baetis alpinus Pictet (Ephemeroptera: Baetidae) in fragmented alpine streams. Heredity 86 (4),395-403. doi: 10.1046/ j.1365-2540.2001.00843.x http://www.blackwell-synergy.com/links/doi/10.1046/j.1365-2540.2001.00843.x/abs/
Morihara,DK; McCafferty,WP 1979a The Baetis larvae of North America (Ephemeroptera:Baetidae). Transactions of American Entomological Society 105, 139-221.
Morihara,DK; McCafferty,WP 1979b Systematics of the propinquus group of Baetis species (Ephemeroptera: Baetidae). Annals of the Entomological Society of America 72, 130-135.
Peckarsky,BL; Hughes,JM; Mather,PB; Hillyer,M; Encalada,AC 2005 Are populations of mayflies living in adjacent fish and fishless streams genetically differentiated? Freshwater Biology 50(1), 42-51. doi: 10.1111/j.1365-2427.2004.01292.x Abstract
Pennack,RW; Ward,JV 1986 Interstital faunal communities of the hyporheic and adjacent groundwater biotopes of a Colorado mountain stream. Archiv für Hydrobiologie Suppl. 74 3, 356-396.
They found Baetis sp. nymphs in the hyporheic zone of the South Platte river in the Front Range of Colorado at 1863 meters elevation.
Poff,NL; Olden,JD; Viera,NKM; Finn,DS; Simmons,MP; Kondratieff,BC 2006 Functional trait niches of American lotic insects: traits-based ecological applications in light of phylogenetic relationships. Journal of the North American Benthological Society 25 4, 730-755.
Here are the traits for this species from the Appendix:
| Life History |
Voltinism |
Bi or multivoltine - more than 1 generation/yr |
| Development |
Fast Seasonal |
| Synchronization of emergence |
Poorly synchronized |
| Adult life span |
Less than 1 week |
| Adult ability to exit |
Absent |
| Ability to survive dessication |
Absent |
| Mobility |
Female dispersal |
Less than 1km flight before laying eggs |
| Adult flying strength |
Weak - cannot fly into light breeze |
| Occurance in drift |
Abundant (dominant in drift samples) |
| Maximum crawling rate |
Very low - less than 10cm/hour |
| Swimming ability |
Strong |
| Morphology |
Attachment |
None (free ranging) |
| Armoring |
None (soft -bodied forms) |
| Shape |
Streamlined - fusiform |
| Respiration |
Gills |
| Size at maturity |
Small (less than 9mm) |
| Ecology |
Rheophily |
Depositional and erosional |
| Thermal preference |
Cool/Warm eurythermal |
| Habit |
Swim |
| Trophic habit |
Collector-gatherer |
The United States Geological Survey (USGS) National Water Quality Assessment Data Warehouse (NAWQA) shows this genus present in Gunnison County. Data as of 1Sep2005
Waltz RD; McCafferty WP. 1987. New genera of Baetidae for some Nearctic species previously in Baetis Leach (Ephemeroptera). Annals of the Entomological Society of America 80:667-670.
Wang,TQ; McCafferty,WP 1996 New diagnostic characters for the mayfly family Baetidae (Ephemeroptera). Entomological News 107 2, 207-212.
Wiersema,NA; Nelson,CR; Kuehnl,KF 2004 A new small minnow mayfly (Ephemeroptera: Baetidae) from Utah, USA. Entomological News 115 3, 139-145.
They provide a key for Baetis larvae to species. Abstract: "Baetis moqui, new species, is described from larvae collected from the Escalante Canyon Region of Garfield County in south-central Utah. The new species is unique among North American Baetis in having gill number one highly reduced or absent. Labial morphology and overall setation characteristics indicate a close relationship between B. moqui and the northern California species Baetis alius and the eastern North American species Baetis pluto. An updated key to the North American Baetis larvae is provided. "
Wipfli,MS, Hudson,J and Caouette,J 1998 Influence of salmon carcasses on stream productivity: response of biofilm and benthic macroinvertebrates in southeastern Alaska, U.S.A. Can. J. Fish. Aquat. Sci. 55(6): 1503-1511 Abstract
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