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SUMMARYThe ultrastructure and carbohydrate chemistry of Glaucosphaera vacuolata Korsh. were studied to clarify the uncertain taxonomic position of this alga. Serial thin sections reveal that the double membrane bounded photosynthetic apparatus of Glaucosphaera, described by previous investigators to consist of many chromatophores or cyanelles, is a single, highly lobed chloroplast without a pyrenoid. Thylakoids are single and bear phycobilisomes. The single nucleus is centrally located and surrounded by Golgi bodies. Starch granules are located outside the chloroplast and are not menabrane bounded. Chemical analysis of the solubilized starch granules by butanol precipitation, iodine staining, and enzymatic digestion indicates the presence of both amylose and amylopectin. It is concluded that Glaucosphaera is a red alga and should be assigned to the order Porphyridiales.

S U M M A R Y Previous reports, based on studies involving approximately 10 genera of the higher red algae, have concluded that floridean starch is composed of arnylopectin only. Our investigations on seven members of the Porphyridiales and a member of the Bangiales (Erythrocludiu) have demonstrated conclusively the presence of amylose in red algal starch.

A laboratory investigation was conducted to study the extent and efficiency of cadmium bioaccumulation in Scenedesmus obliquus by subjecting this alga to varied sublethal Cd concentrations. The influence of cell population age on Cd bioaccumulation was also studied. Under the experimental conditions employed, growth was not significantly affected by Cd concentrations ranging from 0.01 ppm to 1.00 ppm. At concentrations above 1.00 ppm, however, growth was inhibited markedly. Increases in external Cd concentration caused an increase in total bioaccumulation over the entire range of concentrations, which did not significantly affect growth. Efficiency of Cd bioaccumulation was also concentration dependent, but maximum accumulation efficiency occurred in a medium with a Cd concentration lower than that medium in which maximum total bioaccumulation occurred. Age of the cell population influenced the extent of Cd bioaccumulation. Rapidly growing, young cultures accumulated less Cd than older cultures approaching stationary growth phase.

A laboratory study was conducted, to examine and compare the sensitivity of vegetative cells and zygospores of Chlamydomonas moewusii Gerloff to 20 different herbicides. Under the culture conditions employed, both vegetative growth and zygospore germination were affected by certain herbicides and not by others. Over a concentration range from 1.0–80.0 μM, growth was inhibited to various degrees by herbicides containing ametryne, paraquat, endothall, diquat, diuron, linuron, propanil, dinoseb, ioxynil, atrzine, prometon, and alachlor. Zygospore germination was inhibited significantly by herbicides containing dinoseb, endothall, parquet, diquat, propanil, linuron, ioxynil, ametryne, fenac and picloram at 80.0 μM concentrations. Comparisons of the results obtained indicate that concentrations of herbicides which affect growth may or may not effect zygospore germination and vice versa. Zygospores may be more resistant than vegetative cells to some but not all herbicides.