Publication Abstract

Multivariate trends in groups of phytoplankton species in the North Sea

M.D. Nicholson, R. Fryer and D. Maxwell

When assessing trends among a group of variables. there may be a joint underlying trend not evident from direct plots of the individual variables against time. To provide a simple summary of this underlying trend. linear projections Of' multiple time series are constructed to maximize the variance explained by a fitted smoother. A number of tests for assessing the significance of the fitted trend are given. The method is applied to densities of phytoplankton groups observed over a 13-month period and used to contrast the tends observed in two different areas within the southern North Sea.

Reference:

M.D. Nicholson, R. Fryer and D. Maxwell, 1998. Multivariate trends in groups of phytoplankton species in the North Sea. ICES Journal of Marine Science. 55: 581-586