EFFECTS OF NITROGEN AND PHOSPHORUS ON THE ENDOSYMBIONT LOAD OF RHOPALODIA GIBBA AND EPITHEMIA TURGIDA (BACILLARIOPHYCEAE)

Hudson R. DeYoe, Rex L. Lowe, Jane C. Marks

Research output: Contribution to journalArticle

51 Scopus citations

Abstract

Diatoms of the family Epithemiaceae possess a unicellular nitrogen‐fixing cyanobacterial endosymbiont. We investigated the potential of extracellular nitrogen and phosphorus concentrations to affect the endosymbiont load of Rhopalodia gibba O. Müll, and Epithemia turgida Ehr. in field and culture populations. In a growth chamber experiment, monoclonal cultures of R. gibba were exposed to three levels of nitrate‐nitrogen. Nutrient‐diffusing substrates were used in a lake environment to create nine microhabitats of varying nitrogen and phosphorus ratios for natural populations of R. gibba and E. turgida. The number of endosymbionts per diatom increased as ambient nitrogen became limiting; mean endosymbiont volume increased as nitrogen increased. The mean endosymbiont surface area: volume ratio decreased with increasing nitrogen. Total endosymbiont volume per diatom (the product of the number of endosymbionts per diatom and their individual biovolumes) did not have a simple response to increasing nitrogen. Phosphorus limitation uncoupled the relationship between endosymbiont load and nitrogen. We suspect that flexibility of the endosymbiont load can reduce the metabolic cost to the diatom if the endosymbionts are dependent on the diatom for a resource.

Original languageEnglish (US)
Pages (from-to)773-777
Number of pages5
JournalJournal of Phycology
Volume28
Issue number6
DOIs
StatePublished - Dec 1992
Externally publishedYes

Keywords

  • Bacillariophyceae
  • Cyanobacteria
  • Epithemia turgida
  • Rhopalodia gibba
  • endosymbiosis
  • nitrogen
  • nitrogen fixation
  • nutrient limitation
  • phosphorus

ASJC Scopus subject areas

  • Aquatic Science
  • Plant Science

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