How Salinity Changes in an Intertidal Zone May Affect Population Dynamics of Littorina scabra (Linaeus 1758) in Northern Coasts of Persian Gulf

摘要

The effects of salinity on the growth rate and survival of juvenile Littorina scabra gastropods reared in the laboratory from the young of young females collected in estuarine, intermediate, and marine habitats were studied. The optimum growth conditions of juveniles were dependent on the salinity regime in their original habitat. The young group of females from the marine site showed maximum survival at a salinity of 40 parts per thousand, the value corresponding to the normal salinity in their native habitat during the breeding period, while at 30 parts per thousand, the growth of juveniles from this population was strongly suppressed. Juveniles originating from the estuarine habitat were able to maintain equally high growth rates at 40 and 30 parts per thousand; however, at 30 parts per thousand, they grew significantly faster than juveniles from the marine site. The progeny of females from the intermediate habitat showed intermediate growth rates at 30 parts per thousand. Fluctuating salinity (40-10-40 parts per thousand) had an adverse effect on the growth of juvenile Littorina, irrespective of the parental habitat. The differences in survival, size, and growth rates of the progeny of L. scabra in habitats with different salinity regimes are discussed in relation to their potential adaptive significance to life in estuaries