ORGANIZATION AND DISTRIBUTION OF PHYTOPLANKTON COMMUNITIES.
Final technical rept.,
INSTITUTO DE INVESTIGACIONES PESQUERAS BARCELONA (SPAIN)
Pagination or Media Count:
The different measurements of environmental factors or of phytoplankton populations, obtained in different points of a volume of water, can never be considered as random samples of an uniform statistical universe. It is more appropriate to study distributions as dependent of position in space and, as manifestations of an organization. The density of one given species in a small volume of water is not only a function of local environmental properties, but also depends on the concentration of the same species in some neighboring area. Diffusivity and water turbulence is very important, as are the gradients and generated flows. Patches of strongly stratified water, poor in nutrients is another unit of reference. A careful consideration of the distribution of phytoplankton advises a change in the order of importance given to the different factors. Salinity and temperature have been often considered as very important factors in plankton distribution, but from recent evidence turbulence and nutrient contents are, besides light, the chief factors in explaining phytoplankton populations. It was discovered that not only total amount of plant pigments, but also relative concentration of pigments could be meaningful. Pigment ratios could be substituted, in the practice, by ratios between absorbancies at given wavelengths of the pigment extracts. Thus, progress in plant physiology emphasizes the idea that the diversity of pigments is an expression of properties of the photosynthetizing apparatus, and that the said pigment ratios, besides any taxonomical interpretation, have implications of true ecological relevance concerning the degree of evolution or the stage of succession.
- Biological Oceanography