Effects of calcium oxide (quicklime) on non-target organisms in mussel beds

Three experimental tanks (area 1.2 x 0.9 m), set up to simulate conditions in a natural mussel bed, were stocked with mussels Mytilus edulis, bloodworms Glycera dibranchiata, sandworms Nereis virens, periwinkles Littorina littorea, juvenile lobsters Homarus americanus, and starfish Asterias vulgaris. To avoid predation, the worms were confined to mudfilled basins within each tank. After 1 week acclimation, quicklime (1.5 kg per tank) was applied by hand to the surface waters of each tank. All starfish died within 12 h, but no detrimental effects were detected in the other species. Histological examination, conducted 1 week after quicklime application, revealed no abnormalities in lobster gills, worm parapoidia or mussel gills, and all animals except starfish were still surviving 6 months after the experiment ended. These results indicated that the use of quicklime to control starfish predation in natural mussel beds would not adversely affect other species likely to be present.