Bioassay methods for evaluating the toxicity of heavy metals, biocides and sewage effluent using microscopic stages of giant kelp Macrocystis pyrifera (Agardh): A preliminary report

Abstract

Methods for using early life stages of giant kelp Macrocystis pyrifera in toxicity tests intended for evaluating the toxicity of municipal sewage effluents are given. Included are methods for both a short-term (48-h) toxicity test, and a long-term (16-day) toxicity test. Preliminary results of experiments with zinc sulfate, sodium pentachlorophenate, and a primary-treated sewage effluent showed that early life stages of Macrocystis have a variable sensitivity to these toxicants. No Observed Effect Concentrations (NOECs) for effects of zinc sulfate on germination of Macrocystis zoospores ranged from 1730 μg/liter to 5500 μg/liter in 3 separate 48-h experiments. The NOECs for zinc effects on the growth of Macrocystis zoospore germination tubes ranged from 550 to 1090 μg/liter in three 48-h experiments. The NOEC for zinc effects on sporophyte production by Macrocystis was 1070 μg/liter in a 16-day experiment. The fungicide and herbicide sodium pentachlorophenate significantly inhibited Macrocystis zoospore germination, and gametophyte reproduction at concentrations of 32 μg/liter and greater (NOEC < 32 μg/liter for both tests), and was more toxic to kelp than zinc. Primary-treated-sewage effluent significantly inhibited zoospore germination at concentrations greater than 1% effluent (NOEC = 0·56% effluent). The results of these preliminary experiments indicate that early life stages of Macrocystis pyrifera are amenable to evaluating the toxicity of a variety of toxicants, including sewage effluents, and that Macrocystis has a variable sensitivity to toxicants depending on the nature of the toxicant and the endpoint being tested.