Production of intracellular and extracellular algal hpid classes was examlned over a range of rates of supply of Inorganic nitrogen The marine dlatom Phaeodactylum tncornutum was studied using 2 new techniques Cage culture turb~dostdts wt rl used for growing the phytoplankton These are continuous cultunng systems which provldc-a h~g h l y controlled algal environment The Chromarod-Iatroscan TLC/FID system was used for llpid class separat~on and quantification This permitted the resoluhon and detechon of as many as 10 algdl lipid classes plus an lnternal standard for accurate quanhflcauon Up to 3 cultunng units were supplled wlth medium of known nutrient content simultaneously, and particulate intracellular hplds together wlth d~ssolved hplds in the effluent media were monitored Intracellular synthesis of a storage class, triglycende, was clearly triggered by nltrogen stress, whlle synthesis of membrane-assoc~ated polar lipid cIasses was reduced under these conditions Partlculate tnglycerlde yield was higher at lower levels of nitrogen supply despite lower growth rates Different amounts and different types of dissolved extracellular lipid classes were produced under nitrogen-stressed and nitrogen-replete condltlons

Production of intracellular and extracellular lipid classes by Chaetoceros gracilis was studied over a wide range of supply rates of inorganic phosphorus and silicon. The cage culture turbidostat, a continuous culture technique providing closely controlled nutrient concentrations and population densities, was used for growing the diatom. Nutrient, intracellular lipid and chlorophyll a analyses were performed over the whole range of nutrients used, but dissolved lipid production was measured only at the extremes of the ranges of nutrient concentrations. The production of triglycerides, a storage class of lipids, was triggered by nutrient stress with either phosphorus or silicon, as had earlier been demonstrated with nitrogen. The synthesis of phospholipids was reduced under phosphorus stress, while the synthesis of chlorophyll a was increased by silicon stress. The increase in chlorophyll a per cell under silicon stress brings into question the use of this pigment as a measure of biomass. Particulate lipid y e l d was highest in intermediate concentrations of both nutrients.

Organic materials able to complex ionic copper were extracted from seawater by a technique involving the saturation of complexing sites by the addition of excess ionic copper, followed by adsorption on a Sep-Pak C 18 column. Application of this technique to samples from a series of cruises on the Scotian Shelf covering 3 seasons demonstrated a correlation between biological activity, and particularly phytoplankton productivity, and ligand production. The complexing sites were associated with the polar fraction of organic materials, as determined by compound class separations using the Chromarod-Iatroscan technique.

Copper-complexing organic ligands were produced by actively-growing phytoplankton during spring blooms in the Bedford Basin and the Northwest Arm, Halifax. Nova Scotia. Iatroscan TLC/ FID and TLC/AAS analysis showed the naturally occurring ligands to be qualitatively similar to those produced by phytoplankton grown in batch and continuous culture. The Bedford Basin bloom was interrupted by an extremely heavy rainfall, resulting in a large contribution of material, including organic ligands, from terrestrial sources. The ligand contributed from this source could be shown to be qualitatively different from that produced in situ by bloom organisms.

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