, Volume 105, Issue 1, pp 27–43

Seasonal variation of nutrients, organic carbon, ATP, and microbial standing crops in a vertical profile of Pyramid Lake, Nevada

  • K. Hamilton-Galat
  • D. L. Galat

DOI: 10.1007/BF00025174

Cite this article as:
Hamilton-Galat, K. & Galat, D.L. Hydrobiologia (1983) 105: 27. doi:10.1007/BF00025174


Previous studies of Pyramid Lake, Nevada, led to the hypothesis that detritus could be an important food source for zooplankton because abundance of palatable algal species did not seem to be enough to support the zooplankton community throughout the year. Furthermore, a large portion of the annual primary productivity was attributed to a nonpalatable blue-green alga, Nodularia spumigena. We felt this alga became important to the Pyramid Lake aquatic community upon death, as edible detritus and a source of new nitrogen. Changes in pelagic detritus concentrations and microbial standing crops were monitored to determine the availability of these potential foods. Epilimnetic particulate organic carbon (POC) was primarily living phytoplankton. During holomixis and following spring primary production, hypolimnetic POC was 60–97% detrital, but these profundal POC concentrations were low (ca 650 µg l-1). Detritus-bacteria aggregates were observed only following the September cyanophyte bloom.

Although pelagic detritus availability for zooplankton was low, bacterial populations were sufficient to be at least a supplemental food source. Bacteria numbers ranged from 0.50 106 to 24.7 106 ml-1 and increased in response to photosynthetic peaks. Microbial diversity, contribution to POC, and particle association were notable after July. The percentage of living carbon (assessed with ATP measurements) attributable to bacteria was highest in late summer and fall hypolimnetic samples.

Patterns of change in organic phosphorus and nitrogen, the presence of a nitrogen-fixing cyanophyte, the N:P ratio, and results of other research demonstrated that non-nitrogen-fixing algae of Pyramid Lake are limited by inorganic nitrogen. The importance of N. spumigena to the aquatic community appeared to be as a source of new nitrogen, rather than as a forage; its mineralization is critical for the growth of palatable diatoms and green algae following winter mixing.


saline lakesATPbacterianutrientscarbonPyramid Lake

Copyright information

© Dr W. Junk Publishers 1983

Authors and Affiliations

  • K. Hamilton-Galat
    • 1
  • D. L. Galat
    • 1
  1. 1.Colorado Cooperative Fishery Research UnitColorado State UniversityFort CollinsU.S.A.