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Natural plankton assemblages were incubated with a small piece of silicone. Tygon or latex rubber tubing in 200 m1 of culture to determine potential long-term toxic effects of the tubing. Drastic decreases in cell numbers and chlorophyll fluorescence indicated that over 95 "h of the phytoplankton were killed by the latex rubber tubing in 4 d. Even a 1 mm piece of latex tubing lulled -90 % of the phytoplankton. The most resistant specles were Thalassjosira spp. and pennate diatoms. Growth of heterotrophic bodonid flagellates was unaffected by small amounts of latex tubing (1 mm) and larger pieces decreased growth only marginally. Bacterial numbers decreased ~nit~ally, but resistant forms began to grow at the end of the experiment. New unwashed Tygon tubing significantly decreased phytoplankton growth rates, but much less than latex tubing. Washing Tygon tubing, by pouring as little as 200 m1 of seawater through a 1 m piece of 0.6 cm diameter tubing, removed this toxlc effect. No inhibitory effects were found with silicone tubing. Short-term effects of the presence of tubing in the culture medium were documented by measuring phytoplankton photosynthetic rates (14C uptake) and 3 H -t h y m i ~n e incorporation into bacteria. Latex and unwashed Tygon tubing significantly decreased these metabolic rate processes. Tubing effects on zooplankton survival, fecundity and egg viability were tested for the copepod Acartia clausii. Latex tubing had the largest effect on these parameters followed by Tygon tubing. Silicone tubing exerted no significant effect.
Price et al. (Wed,) studied this question.