Matrix models for algal life history stages

Matnx models based on size and stage, corresponding to the monophasic, biphasic and triphasic life histones of algae have been constructed. Similarities and differences of these models with the Leslie matnx model, as well as with other extensions and modif~cations of it, are discussed. Two examples are given to show the utility of these models: one based on field data for Sargassum siliquosurn J. Ag. and a second, based on data for Laminaria longicruris Pyle., taken from the literature. Stable size distribution, reproductive values, sensitivity and elasticity of these models are analyzed. Many algae show discrete episodes of growth, reproduction, die back and regeneration. Hence, discrete matrix models appear to realistically describe the life history processes of these algae.