New Zealand Journal of Marine and Freshwater Research abstracts

---

Spatial heterogeneity of the dominant cyanobacteria in the surface waters of Lake Rotongaio

ALEXANDER J. HORNE¹

MARCIE L. COMMINS²

¹Department of Civil Engineering, and Sanitary Engineering and Environmental Health Research Laboratory, University of California, Berkeley California 94720, U.S.A.

²Department of Zoology University of California Davis, California 95616, U.S.A.

Abstract Spatial heterogeneity (patchiness) was measured at 30 stations in Lake Rotongaio over a short period in the austral summer of 1987. The winds before collection at 1000 to 1100 hours were low, 1.0-1.7 ms"¹, and a slight surface dusting indicated visible surface scums of cyanobacteria. Counts of phytoplankton samples from throughout the lake indicated that the small (3-5 um diameter) single-filaments of an Anabaena species dominated the surface waters. Heterocysts were present in about half of the filaments and nitrogenase activity was high (x = 1.10 nmol C2H4I-¹ h~'). Nutrients (PO₄, NH₄, NO₃), particulate N and P, temperature, chlorophyll, heterocyst numbers, algal biomass, nitrogenase activity, photosynthesis, dissolved organic N and P, and the zooplankton abundance and species composition were measured at all 30 sites. Within- and between-patch variance was investigated by sampling in triplicate at each station for nitrogenase activity and chlorophyll a, and at one station for zooplankton. Within-sample variation of nitrogenase activity was estimated by a separate series of replicated measurements on ali-quots of the same sample.

New Zealand Journal of Marine and Freshwater Research, 1987, Vol. 21: 527. 0028-8330/87/2103-0527$2.50/0 © Crown copyright 1987 Received 13 March 1987; accepted 29 May 1987

PDF file of entire paper: medium quality (71K); (scanned from paper original: notes about this process)

---

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