An increase in temperature in water bodies can lead to a noticeable change in the life cycle of parasites, according to the research of scientists from the A.N. Severtsov Institute of Ecology and Evolution RAS. Due to global warming, it is possible to change the “parasite-host” chains, which will lead to a restructuring of the entire appearance of freshwater ecosystems.
In recent years, there has been growing interest among scientists in how temperature affects the risk of transmission of infections in ecosystems, or, in other words, the interaction of parasites and their hosts. To find out, scientists from the IEE RAS studied how temperature affects the separation of the dispersal stages (larvae/cercariae) of two closely related species of parasitic flatworms (trematodes): Rhipidocotyle campanula and R. fennica. The first intermediate host in these species of trematodes is the mollusk - common toothless (Anodonta anatina), the second roach. And only the final owners - predatory fish - differ.
To conduct the experiment, scientists collected mollusks from rivers and distributed them in flow tanks with three temperature regimes. The average temperature in these tanks was 18°C (range 7-24°C), 15°C (7-20°C) and 13°C (6-18°C). The design of the experiment did not assume a constant temperature of the molluscs. On the contrary, it had to fluctuate in accordance with seasonal changes, as in natural ecosystems, to emulate the real world in terms of global warming.
The experiment lasted five months. Every two weeks, the scientists checked whether the molluscs secreted parasitic larvae (cercariae) and, if so, how many.