Distribution and abundance of the alkali fly (Ephydra hians) Say at Mono Lake, California (USA) in relation to physical habitat
- 96 Downloads
The distribution and abundance of larval, pupal, and adult stages of the alkali fly Ephydra hians Say were examined in relation to location, benthic substrate type, and shoreline features at Mono Lake. Generation time was calculated as a degree-day model for development time at different temperatures, and compared to the thermal environment of the lake at different depths.
Larvae and pupae have a contagious distribution and occur in greatest abundance in benthic habitats containing tufa (a porous limestone deposit), and in least abundance on sand or sand/mud substrates. Numbers increase with increasing area of tufa present in a sample, but not on other rocky substrates (alluvial gravel/cobble or cemented sand). Standing stock densities are greatest at locations around the lake containing a mixture of tufa deposits, detrital mud sediments, and submerged vegetation. Shoreline adult abundance is also greatest in areas adjacent to tufa. The shore fly (ephydrid) community varies in composition among different shoreline habitats and shows a zonation with distance from shore.
The duration of pupation (from pupa formation to adult eclosion) becomes shorter as temperature increases. The temperature dependence of pupa development time is not linear and results in prolonged time requirements to complete development at temperatures below 20 °C. About 700 to 1000 degree-days are required to complete a generation. Degree-days of time available in nature declines by 10 to 50% at depths of 5 and 10 metres relative to surface waters (depending on the extent of mixing), resulting in fewer possible generations. Essentially no growth would be expected at 15 m, where temperature seldom exceeds the developmental minimum. It is concluded that reduced substrate availability and low temperatures may limit productivity of the alkali fly at increasing depths in Mono Lake.
Key wordsEphydra life cycle development distribution Mono Lake substrate
Unable to display preview. Download preview PDF.
- Aldrich, J. M., 1912. The biology of some western species of the dipterous genus Ephydra. J. N.Y. Ent. Soc. 20: 77–99.Google Scholar
- Barnby, M. A., 1987. Osmotic and ionic regulation of two brine fly species (Diptera: Ephydridae) from a saline hot spring. Physiol. Zool. 60: 327–338.Google Scholar
- Burch, J. B., J. Robbins & T. Wainwright, 1977. Botany. In D. W. Winkler (ed.), An ecological study of Mono Lake, California. University of California at Davis, Institute of Ecology, Publ. no. 12: 114–142.Google Scholar
- Collins, N. C., 1980a. Population ecology of Ephydra cinerea Jones (Diptera: Ephydridae), the only benthic metazoan of the Great Salt Lake, USA, Hydrobiologia 68: 99–112.Google Scholar
- Collins, N. C., 1980b. Developmental responses to food limitation as indicators of environmental conditions for Ephydra cinerea Jones (Diptera). Ecology 61: 650–661.Google Scholar
- Dunn, R. C., 1953. The origin of the deposits of tufa at Mono Lake. J. Sed. Petrol. 23: 18–23.Google Scholar
- Elliot, J. M., 1977. Some methods for the statistical analysis of samples of benthic invertebrates. 2ne edition. Freshwater Biological Association Scientific Publication No. 25, Ambleside, England. 160 pp.Google Scholar
- Essig, E. O., 1926. Insects of western North America. The Macmillan Co. New York, 1050 pp.Google Scholar
- Herbst, D. B., 1986. Comparative studies of the population ecology and life history patterns of an alkaline salt lake insect: Ephydra (Hydropyrus) hians (Diptera: Ephydridae). PhD thesis, Oregon State University, Corvallis. 206 pp.Google Scholar
- Herbst, D. B., 1988. Comparative population ecology of Ephydra hians Say (Diptera: Ephydridae) at Mono Lake (California) and Abert Lake (Oregon). Hydrobiologia 158: 145–166.Google Scholar
- Herbst, D. B., F. P. Conte & V. J. Brookes, 1988. Osmoregulation in an alkaline salt lake insect, Ephydra (Hydropyrus) hians Say (Diptera: Ephydridae), in relation to water chemistry. J. Insect Physiol. 34: 903–909.Google Scholar
- Merritt, R. W. & K. W. Cummins (eds), 1984. An introduction to the aquatic insects of North America. 2nd edition. Kendall/Hunt Publishing Co., Dubuque, IA. 722 pp.Google Scholar
- National Academy of Sciences, 1987. The Mono Basin ecosystem: effects of changing lake level. National Academy press, Washington, D.C.: 272 pp.Google Scholar
- Nemenz, H., 1960. On the osmotic regulation of the larvae of Ephydra cinerea. J. Insect Physiol. 4: 38–44.Google Scholar
- Say, T., 1830. Descriptions of North American dipterous insects. J. Acad. Nat. Sci. Philadelphia. 6: 183–188.Google Scholar
- Simpson, K. W., 1976. The mature larvae and puparia of Ephydra (Halephydra) cinerea Jones and Ephydra (Hydropyrus) hians Say (Diptera: Ephydridae). Proc. Ent. Soc. Wash. 78: 263–269.Google Scholar
- Stine, S., 1988. Geomorphic and geohydrographic aspects of the Mono Lake controversy. In D. B. Botkin et al. (eds), The future of Mono Lake. University of California Water Resources Center, Riverside. Report No. 68. Appendix D: 1–135.Google Scholar
- Sweeney, B. W., 1984. Factors influencing life history patterns of aquatic insects. In Resh, V. H. & D. M. Rosenberg (eds), The ecology of aquatic insects. Praeger Publishers, N.Y.: 56–100.Google Scholar
- Wirth, W. W., 1971. The brine flies of the genus Ephydra in North America (Diptera: Ephydridae). Ann. ent. Soc. Am. 64:357–377.Google Scholar
- Wirth, W. W., 1975. A revision of the brine flies of the genus Ephydra of the Old World (Diptera: Ephydridae). Ent. Scand. 6: 11–44.Google Scholar
- Wirth, W. W. & W. N. Mathis, 1979. A review of the Ephydridae (Diptera) living in thermal springs. In D. L. Doenier (ed.), First symposium on the systematics and ecology of Ephydridae (Diptera). North American Benthological Society publ. Lawrence (KS): 21–45.Google Scholar