![Sample our Environment & Agriculture journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5934/TOC-Subject-Sample-2021-Environment-Agriculture.jpg"})
Abstract
The species composition of the Lake Okaro (New Zealand) phytoplankton community was described as part of a detailed study of the lake ecosystem during 1979/80. The dimensions of each species were measured to estimate cell biovolume and to define the morphometric characteristics of each population. The algal dominants (> 50% of community biomass) were bloom‐forming cyano‐phytes in summer through to early winter (Microcystis aeruginosa Kütz., Anabaena flos‐aquae (Lyng.) Bréb., A. spiroides Kleb.), centric diatoms in autumn and winter (Melosira granulata (Ehr.) Ralfs, M. granulata var. angustissima Mull.), and colonial chlorococcaleans in spring (Coelastrum microporum Naegeli, Micractinium pusillum Fre‐senius, Oocystis parva West and West, Actinastrum hantzschii Lagerh.). These algal communities were different to the communities recorded in Lake Okaro 10 years earlier. M. granulata dominated the winter plankton in 1980 but not 1970. Colonial chlorococcaleans were more important constituents throughout the year than during 1970, and a previously unrecorded, non N2‐fixing blue‐green alga (M. aeruginosa) produced water blooms from December 1979 to June 1980. The chlorococcalean and cyanophyte shifts suggest that further enrichment of this eutrophic water body has occurred over the decade 1970–80.
