Bull. Environ. Contam. Toxicol. (1988) 40:503-509 9 1988 Springer-Verlag New York Inc. Environmental Contamination iand Toxicology Effects of Calcium Oxide (Quicklime) on Non-target Organisms in Mussel Beds Sandra E. Shumway, 1 Donald Card, 1 Rodman Getchell, 1 and Carter Newell 2 1Department of Marine Resources, West Boothbay Harbor, Maine 04575 and 2Great Eastern Mussel Farms, Inc., Tenants Harbor, Maine 04860 The use of quicklime (calcium oxide) as a deterrent to starfish predation is a longstanding practice amongst marlculturlsts and was first suggested by Wood (1908). Quicklime is a strong alkali that reacts with and immediately destroys the unprotected starfish tissues. It is a fairly inexpensive technique and has been reported by the National Oceanic and Atmospheric Administration (NOAA) to be nonharmful to oysters, other molluscs or fish. Since quicklime rapidly combines with water to form calcium carbonate, it does not introduce any long-lasting poison into the environment (North 1969). Bottom culture of mussels (Mytilus edulis) has become a multi-million dollar industry in Maine. For periods of bottom grow-out longer than one year, starfish predation can account for considerable mortality. In one instance, starfish predation caused a loss of 6000 bushels of mussels (36,000 Ibs; 7.92 x 10 ~ kg) over a 15 acre (4047 m 2) lease section which amounted to 50% of the crop (Newell, unpublished). On August 29, 1979, the U.S. Environmental Protection Agency deleted quicklime from their list of hazardous substances (Anonymous 1979). In spite of this acceptance and existence of data which indicate that quicklime is not detrimental to oyster beds (see discussion), controversy still exists regarding the use of large quantities of quicklime to control starfish populations on 'wild' shellfish beds. There have been few studies in which the possible effects of quicklime on other organisms of the treated areas have been instigated and the present study was undertaken to determine whether or not there would be any adverse effects of quicklime on mussel beds. MATERIALS AND METHODS Three experimental tanks were set up under identical conditions designed to resemble as closely as possible the conditions on a natural mussel bed. Each tank contained I0 cm of crushed gravel covered by a 5 cm deep layer of mud. The tanks were supplied with Send reprint requests to S.E. Shumway at the above address. 503