Consejo Superior de Investigaciones Científicas, Scientia Marina, S1(73), p. 59-72, 2009
DOI: 10.3989/scimar.2009.73s1059
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seelig platz 1, 24118 Kiel, germany. ³ institute of sea Fisheries, Johann heinrich von thünen-institut, Federal research institute for rural areas, Forestry and Fisheries, palmaille 9, 22767 hamburg, germany. suMarY: the small pelagic sprat (Sprattus sprattus) is a key ecologic player in the Baltic sea. however, there is long-term variability in recruitment which is thought to be influenced by fluctuations in abiotic and biotic conditions experienced during the early life stages. this study concentrates on the influence of different ambient salinities on sprat egg development, egg buoyancy and survival as well as early yolk sac larval morphometric traits. egg buoyancy significantly decreased with increasing salinity experienced during fertilization and/or incubation experiments. Field egg buoyancy measurements in 2007 and 2008 exhibited annual and seasonal differences in specific gravity, potentially associated with changes in adult sprat vertical distribution. neither egg development time nor the duration of the yolk sac phase differed among salinity treatments. at eye pigmentation, larval standard length exhibited high variance among individuals but did not differ among treatments. the largest ecological impact of salinity experienced during spawning was the modification the buoyancy of eggs and yolk sac larvae, which determines their vertical habitat in the Baltic sea. there are strong thermo-and oxyclines in the Baltic sea, and thus salinity can indirectly impact the survival of these early life stages by modifying the ambient temperatures and oxygen conditions experienced.