Experimental assessment of the influence of certain aspects of baltic herring spawning on the model species of cladocerans
- DOI
- 10.5922/vestniknat-2026-2-5
- Pages
- 79-94
Abstract
Experiments were conducted to investigate the influence of gametes and water collected from spawning aggregations of the Baltic herring Clupea harengus membras in the Vistula Lagoon on the survival, growth, molting frequency, number of eggs in the brood chamber, and offspring production of the model planktonic crustacean species Daphnia magna. In the first series of experiments, a fixed volume of a suspension of gametes from male and female Baltic herring (gonads at stage V of maturity) was added to the experimental containers and compared with the control. In the second series of experiments, daphnids were acclimated to brackish water (up to 3 PSU), after which they were used in the control and experimental groups to assess the effect of water collected from Baltic herring spawning grounds in the lagoon area. In media containing Baltic herring gametes, the fecundity of daphnids was significantly lower than the control values. The growth of daphnids was stimulated by the addition of female gonads (average molting frequency 114 %), whereas the addition of male gonads inhibited growth (54 %) relative to the control (84 %). Water collected from the Baltic herring spawning grounds did not exert a significant effect on the growth or molting frequency of daphnids, but it significantly stimulated the production of parthenogenetic eggs in the brood chamber of daphnids (control: 7.7; experiment: 13.0 eggs/female/day). A hypothesis is proposed that Baltic herring gametes, as well as biologically active compounds entering the waters of the Vistula Lagoon during spawning, may influence the growth and fecundity of natural populations of cladoceran crustaceans.