The scyphomedusa Aurelia aurita consumes large amounts of yolk-sac herring larvae in Kiel Fjord. The decline of the larval herring population in late spring coincides with a major population growth of the jellyfish. The size of the larval herring population seems to be more significantly affected by the size of the predator stock than by the size of the parental herring stock.
In brackish water the variety of marine and freshwater parasite species is considerably reduced. The distribution in brackish water of most marine endoparasites is restricted by the salinity tolerance of their hosts, most of the parasite species are more tolerant than their hosts. The influence of salinity and temperature on nine species has been examined; first stage larvae of Contracaecum aduncum develop in 0-32%, salinity; CryptocotyZe lingua proved to be infective at salinities down to 4%,. The greatest resistance was found in Anisakis larvae from herring Clupea harengus, which survived for more than half a year. Parasites in the fish intestines appear to be unaffected by changing water salinities, as the osmolarity in the intestines stays nearly constant. Marine ectoparasites (Acanrhochondria depressa, Lepeophtheirus pectoralis) survive about three times longer than freshwater species (Piscicola geometru, Argulus foliuceus) when salinity is 16%,. High temperature increases the effects of adverse salinities on parasites. There is evidence that none of these ectoparasitic species can develop within the range of 7-20%, salinity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.