New Zealand Journal of Marine and Freshwater Research abstracts
Short communication
Phytoplankton assemblages in North Island lakes of New Zealand: is trophic state,
mixing, or light climate more important?
E. F. Ryan
I. C. Duggan
D. P. Hamilton
D. F. Burger
Centre for Biodiversity and Ecology Research
University of Waikato
Private Bag 3105
Hamilton, New Zealand
email: dburger@waikato.ac.nz
Abstract Relationships between phytoplankton assemblages and
lake trophic state, mixing regime and light climate were investigated in 40
North Island, New Zealand, lakes. We tested the hypothesis that mixing regime
is more important than trophic state or light climate in determining the community
composition of phytoplankton assemblages which were represented as presence/absence
of cyanobacteria and diatom genera. Mixing regime, characterised as a function
of lake size, more accurately predicted summer phytoplankton composition than
indices related to trophic state or light regime. Analysis of similarities
indicated distinct differences in phytoplankton assemblages between
mixed lakes and those that intermittently or periodically stratify. In mixed
lakes, a greater variety of cyanobacteria genera than diatom genera were recorded
compared with lakes that stratify stably in summer. Conversely, relatively
high numbers of diatom to cyanobacteria genera were found in lakes that stratify
compared with mixed lakes. Lakes with different trophic states but similar
mixing regimes shared very similar summer phytoplankton assemblages. None of
the three variables tested was a good predictor of winter phytoplankton composition.
Although phytoplankton biomass may be regulated to a large extent by nutrient
status, this study shows that mixing regime plays a more important role in
regulating phytoplankton composition than either nutrient status or light climate.
Keywords cyanobacteria; diatoms; summer; winter; phytoplankton
assemblages; community; composition
New Zealand Journal of Marine and Freshwater Research, 2006, Vol. 40:
389–398
0028–8330/06/4003–0389 © The Royal Society
of New Zealand 2006
M05050; Online publication date 7 July 2006. Received 10 August 2005;
accepted 23 January 2006
PDF file of entire paper: Print-quality (371K) |
screen-quality (245K)
This year's abstracts |
Journal home page |
All abstracts |
Publishing home page
