TEMPERATURE‐GROWTH RESPONSES OF ALGAL ISOLATES FROM ANTARCTIC OASES1

Publisher Website
Google Scholar
Abstract
Thirty‐five taxa (128 clonal cultures) of Antarctic algae isolated from various habitats were assayed for growth over a range of 2–34°C. Isolates, all unialgal and two axenic, varied markedly in their temperature‐growth responses. Only four taxa belonging to either the Chlamydomonadaceae or Ulotrichaceae were obligately cold‐adapted and incapable of growth at ≥20°C. All isolates grew at temperatures ranging from 7.5 to 18°C, and a few were incapable of growth at ≤5°C. Over one‐third of the isolates grew at 30°C, but none grew at 34°C.Percentages of cold‐adapted clones correlated well with the more stable low temperature habitats. Four chlamydomonad isolates displayed optimum temperatures for growth near their maximum temperatures for growth, both temperatures being well above those of the native habitats. This temperature‐growth response suggests a closer relationship to algae from more moderate thermal regions than one might have supposed. However, the ability to grow at low temperatures and the inability to grow at 34°C suggest that these Antarctic algae are cold temperature adapted. Growth capability at low in situ temperatures is considered more useful ecologically than physiologically‐defined categories for algae based on their maximum temperature for growth.