The figure below is from Bartell, et al. Phycologia 17 (1), 1978, Figure 1.
The figure below is from Bartell, et al. Phycologia
17 (1), 1978, Figure 1.
Lake Wingra, Wisconsin.
Weekly phytoplankton samples were fully identified to
species, and the similarities in composition among weeks were subjected
to multifactorial, statistical analysis. Two principal components
of variation were identified, which in combination corresponded well to
seasons. The numbers beside each point on the graph are the week
of the study. Sample points are connected by a line to emphasize
the temporal sequence of changes. Environmental measurements made
along with the phytoplankton samples were compared for "loading" on these
algal principal components. Those that were significantly correlated
with the principal components are listed beside each axis.
Points in winter clustered together, and points in early and late summer also clustered, meaning that phytoplankton composition remained similar for those weeks. In spring and fall, the community changed strongly from week to week as the lake warmed and stratified or cooled and mixed.
Trends in similarity All nine environmental facotrs were significantly related to one or both of the components. Spring-fall (Y-axis) contrasts related to rapid changes in total phosphorus, temperature and solar radiation. Seven of the nine environmental factors (not irradiance or total phosphorus) correlated with changes along the summer-winter (X-) axis.
Last revised September 25, 2003.