TOXIC EFFECTS OF COPPER ON ATTACHMENT AND GROWTH OF BUGULA NERITINA

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Abstract
The effect of Cu on attachment and growth of B. neritina was detd. by laboratory expts. using various Cu paints and sea-water solns. of graded Cu conc. Cu paint surfaces prevent the establishment of this bryozoan both by repelling attachment of larvae and by inhibiting growth and metamorphosis of ancestrulae. Paints with leaching rates (rate of loss of toxic from the surface) less than 10 [gamma] Cu/cm2/day permit large numbers of larvae to attach and develop, while those with higher Cu leaching rates usually allow only a small % of larvae to attach and completely inhibit their subsequent growth. The presence of a slime film is not prerequisite to affixation of Bugula larvae and has no consistent effect on their attachment. Growth of ancestrulae is inversely proportional to Cu conc. up to a limit of approx. 0.3 rag./liter. Higher concs. completely inhibit growth and kill larvae. Cu concs. greater than 0.2 mg./liter prevent polypide formation, but lesser concs. only retard their development. No acceleration of growth by Cu was observed, although an oligodynamic stimulation of larval attachment is suggested. Bugula ancestrulae can recover and develop after long and intermittent exposures to sublethal dosages of Cu. Length of exposure has little apparent effect on degree of recovery from Cu poisoning. A gradient of toxicity extending outward a few mm. from an effective Cu paint surface is demonstrated.