The Distribution of Trace Elements in Some Species of Phytoplankton Grown in Culture

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Abstract
INTRODUCTIONIn common with other plants, marine phytoplankton will only thrive if they are able to obtain essential trace elements. There is some evidence that shortages of available iron and manganese may occasionally restrict the growth of these organisms (Harvey, 1939, 1947). However, other essential trace metals are present in the sea at concentrations which, although very low, appear to be adequate to sustain abundant growth. The concentrations of trace elements necessary for optimum growth differ considerably from species to species (see e.g. Harvey, 1947; Goldberg, 1952). Krauss & Porter (1954) have demonstrated that manganese, iron and zinc are taken up by the freshwater alga Chlorella pyrenoidosa in proportion to their concentrations in the medium. However, this is not true for all elements, at least so far as the larger algae are concerned (Young & Langille, 1958). The concentrations of trace elements present in phytoplankton grown in culture may also depend on the age and density of the culture. Thus, Hayward (1969) has shown that although iron and zinc were initially rapidly taken up by Phaeodactylum tricornutum from a medium rich in chelated forms of these metals, their concentrations in the cells decreased as their numbers increased. The uptake of trace elements is not confined to those which have a definitely established physiological function.