New Zealand Journal of Marine and Freshwater Research abstracts

---

Cyanobacterial dominance: the role of buoyancy regulation in dynamic lake environments

COLIN S. REYNOLDS¹

ROD L. OLIVER²

ANTHONY E. WALSBY³

¹Freshwater Biological Association Windermere Laboratory, Ambleside United Kingdom (GB-) LA22 OLP

²Murray-Darling Freshwater Research Centre P. O. Box 921, Albury NSW, Australia 2640

³Department of Botany University of Bristol, Bristol United Kingdom (GB-) BS8 1UG

Abstract The interactions of size, shape, and density of cyanobacteria result in a 5-order of magnitude difference in flotation or sinking rates which, in turn, influence the extent of their dispersion in turbulent water masses. Active mixing through resource-replete waters of high clarity favours fast-growing, small-celled species. Where photosyn-thetically active radiation is severely attenuated through the wind-mixed layer, species may rely on turbulent entrainment but must be adapted toward efficient light harvesting (morphological attenuation, enhanced pigmentation). In both strongly segregated waters (light- and nutrient-rich layers separated vertically) and waters experiencing high-frequency fluctuations in vertical mixing and optical depth, emphasis is placed on the ability to make rapid, buoyancy-adjusted vertical movements, favoured by large size. The cyanobacterial life-forms respectively typical of these contrasted limnologi-cal systems - unicellular coccoids (e.g., Synecho-coccus), solitary filaments (e.g., Oscillatoria) and colonial forms (e.g., Microcystis) - illustrate the diversity of evolutionary adaptations to be discerned among the planktonic cyanobacteria and which contributes to their reputation as a prominent and successful group of organisms.

Keywords blue-green algae; buoyancy; carbohydrate; cell size; colony; cyanobacteria; flotation; gas vacuoles; mixing; phytoplankton; sedimentation; sinking

New Zealand Journal of Marine and Freshwater Research, 1987, Vol. 21: 379-390 0028-8330/87/2103-0379$2.50/0 © Crown copyright 1987 Received 19 February 1987; accepted 11 May 1987

PDF file of entire paper: medium quality (1225K); (scanned from paper original: notes about this process)

---

This year's abstracts | Journal home page | All abstracts | Publishing home page