Individual growth rates of salps in three populations

One of the fastest growing planktonic species, the salp Thalia democratica , was analysed for growth rate in three different oceanic blooms in winter, summer and spring. Each bloom was marked by a pair of drogues, and sequentially sampled to obtain a sesies of length frequencies in each population through time. The length frequencies were analysed by an improved method of modal analysis. Length-specific growth rate was calculated from the progression through time of the resulting series of modes. The blooms showed average growth per individual of 10.4, 14.7 and 19.8% in length per hour in winter, summer and spring respectively. These growth rates in the field are compared with growth rates obtained previously in the laboratory, and the reasons for the varying estimates of growth rate in the literature are examined.