Skip to Main Content
Three responses to small changes in stream temperature by autumn-emerging aquatic insectsAuthor(s): Judith L. Li; Sherri L. Johnson; Janel Banks Sobota
Source: North American Benthological Society. 30(2): 474-484
Publication Series: Scientific Journal (JRNL)
Station: Pacific Northwest Research Station
PDF: Download Publication (893.3 KB)
DescriptionIn this experimental study, conducted in coastal Oregon USA, we examined how small increases in summer water temperatures affected aquatic insect growth and autumn emergence. We maintained naturally fluctuating temperatures from 2 nearby streams and a 3rd regime, naturally fluctuating temperatures warmed by 3-5°C, in flow-through troughs from mid-summer until autumn. We added selected abundant Ephemeroptera, Plecoptera, and Trichoptera species to the 3 treatments in late July and observed emergence until early December. We described the taxon-specific responses of the caddisfly Psychoglypha bella and the mayfly Paraleptophlebia bicornuta, both of which survived well in the troughs (67-86%), and the stonefly Mesocapnia projecta, which we did not collect in mid-summer but had colonized all experimental troughs by October. We observed primarily phenological rather than morphological responses to higher water temperatures. The most synchronous emergence of male and female P. bella and P. bicornuta occurred in the trough with the coolest temperatures. Only P. bella emerged asynchronously from the trough with the warmest temperatures. The decreases in synchrony were largely the result of earlier emergence of males. Paraleptophlebia bicornuta were larger and tended towards asynchrony in the trough with water (and temperatures) from their natal stream. Individuals in the trough with the warmest temperature were smaller than individuals in other troughs, but did not emerge earlier. Mesocapnia projecta showed greater synchrony in emergence, which occurred over a shorter interval, than the other species. When exposed to increased water temperatures, autumn-emergent taxa may be most vulnerable to trade-offs between asynchronous emergence and the probabilities for finding mates in unpredictable weather conditions.
- Visit PNW's Publication Request Page to request a hard copy of this publication.
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationLi, Judith L.; Johnson, Sherri L.; Sobota, Janel Banks. 2011. Three responses to small changes in stream temperature by autumn-emerging aquatic insects. North American Benthological Society. 30(2): 474-484.
Keywordsemergence, stream temperature, phenology, Paraleptophlebia, Psychoglypha, Mesocapnia, hyporheos
- A tale of two springs: using recent climate anomalies to characterize the sensitivity of temperate forest phenology to climate change
- Descriptors of natural thermal regimes in streams and their responsiveness to change in the Pacific Northwest of North America
- Life cycle and production of Skwala parallela (Frison) (Plecoptera: Perlodidae) in a Colorado montane stream
XML: View XML