Effects of hydrazine and other toxicants on early life stages of California brown algae

Abstract

Toxicity of hydrazine to early life stages of several species of California brown algae was demonstrated to occur at environmentally relevant concentrations. Effects of hydrazine on benthic organisms had not been previously studied. Preliminary studies evaluated toxicity of boric acid, chlorine (as hypochlorite), lithium ion, tributyltin chloride and Zn(II). A reliable bioassay technique was developed using digital image analysis to measure vegetative growth inhibition of brown algal gametophytes. Hydrazine toxicity threshold of Macrocystis pyrifera gametophytes was almost constant in 10 96-hour experiments, ranging from 3 - 5 ppb (96-160 nM). Differences in resistance to short-term hydrazine exposures were observed among three algal families of the order Laminariales. Two of three tested members of the family Alariaceae, Pterygophora californica and Eisenia arborea were among the most resistant species tested. The three tested species in the family Lessoniaceae, Macrocystis pyrifera, Nereocystis luetkeana and Pelagophycus porra, all fast-growing canopy-formers, were among the most sensitive tested species. Tested representatives of the family Laminariaceae varied in resistance. Laminaria farlowii was resistant. Laminaria dentigera and Laminaria ephemera were fairly sensitive. Hydrazine autoxidation rates varied by an order of magnitude in seawater sampled from different locations. Rates showed strong temperature dependence. Autoxidation at 10°C and below was much slower and indicated a higher activation energy than autoxidation at 20°C and above. Undiluted trace hydrazine powerplant emissions from a time period when algal community composition changed in the vicinity of an outfall were compared to growth inhibition results from multivariate hydrazine toxicity experiments on Macrocystis gametophytes. Results indicated that several trace hydrazine discharges were of sufficient duration and concentration to have inhibited algal microscopic stages.