ABSTRACT

Plankton samples collected in coastal and offshore areas around Japan were analyzed for sodium, potassium, calcium, magnesium, phosphorus and silicon. Zooplankton samples of single or mixed species were used in the experiment, while phytoplankton samples were only of mixed species. Species composition of mixed samples were determined under a microscope. Generally, phytoplankton are much higher in potassium and silicon contents than zooplankton, while zooplankton are higher in sodium and phosphorus contents than phytoplankton. Magnesium and calcium are relatively abundant in the samples of phytoplankton. A correlation was seen between potassium and sodium contents, calcium and magnesium contents and phosphorus and silicon contents of zooplankton and of phytoplankton. The K/Na ratio of phytoplankton is exceedingly higher than that of zooplankton or seaweeds, while the P/Si ratio of phytoplankton is particularly lower than that of zooplankton or seaweed. On the other hand, the values of Ca/Mg ratio of zooplankton, phytoplankton and seaweeds are very close to each other.