TEMPERATURE AND SALINITY EFFECTS ON CALCIFICATION RATE IN MYTILUS EDULIS AND ITS PALEOECOLOGICAL IMPLICATONS1

Abstract

Radioisotopic tracer experiments utilizing ⁴⁵Ca reveal that calcification in the bivalve Mytilus edulis occurs over the range of 5–23.5C at 32.0‰ salinity. Specimens deposited shell over the salinity range of 20–37% at 18.5C. No upper temperature or salinity thresholds were found. Calcification rate varies directly with temperature and salinity and among individuals grown at a single temperature over the 24‐hr period of these experiments, probably because of the discontinuous nature of the calcification process. Paleo‐temperature and paleosalinity determinations, such as by oxygen isotopic composition, of the total M. edulis skeleton would yield results higher than the mean temperature and salinity for the growth locality. Measuring growth in fossil M. edulis shells might be used to determine paleotemperatures and paleosalinities. Determining the number of days in a year in the geologic past on the basis of molluscan skeletal structure is probably not possible.