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Biol Bull 90: 122-140. (April 1946)
© 1946 Marine Biological Laboratory
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TOXIC EFFECTS OF COPPER ON ATTACHMENT AND GROWTH OF BUGULA NERITINA

MILTON A. MILLER 1

1 Division of Zoology, University of California, Davis

Copper paint surfaces prevent the establishment of Bugula neritina (1) by repelling or killing the larvae and (2) by inhibiting growth and metamorphosis of attached larvae.

Copper paints with leaching rates less than 10 micrograms of copper per square centimeter per day permit the larvae to attach in large numbers and to grow and differentiate. Paints with leaching rates greater than 15 micrograms per square centimeter per day allow only a small percentage of larvae to attach and completely inhibit their growth. Large percentages of larvae occasionally attach. to paint surfaces with leaching rates between 10 and 15 micrograms per square centimeter per day, but these do not develop colonies.

No consistent effect of slime film on larval attachment was noted. Its presence is not prerequisite to attachment.

Precise relationships between copper concentration and growth of Bugula ancestrulae are demonstrated. Growth in sea-water solutions of copper is inversely proportional to the concentration up to 0.3 mg. per liter. Higher concentrations completely inhibit growth.

The critical copper concentrations affecting various stages of the early life cycle of Bugula are as follows: (1) Concentrations greater than 0.3 mg. per liter kill larvae and completely inhibit growth of attached forms, (2) concentrations between 0.2 and 0.3 mg. per liter retard growth and prevent polypide formation, and (3) concentrations less than 0.2 mg. per liter retard growth and polypide development.

No stimulation of growth by copper solutions was observed. There was some evidence that small concentrations of copper stimulated attachment of larvae.

Bugula ancestrulae can recover and develop almost normally after seven days exposure to sublethal concentrations of copper. They can recover after repeated immersions in copper solutions that practically prevent growth. Length of exposure has relatively little effect on their ability to recover from copper poisoning.

A gradient of toxicity extending outward a few millimeters from a copper paint surface is demonstrated.






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Copyright © 1946 by the Marine Biological Laboratory.