Nitrification of the lake led to the zombie epidemic among shrimp

Nitrification of the lake led to the zombie epidemic among shrimp

Increasing the availability of nutrients in the ecosystem leads to prosperity parasites — such conclusion was made by the American environmentalists, pass the salt marshy lakes in Massachusetts.

Scientists artificially increased the nitrogen in one of the lakes for 11 years and showed that together with an overall increase in biomass in the lake, the rate of infection with parasitic flat worms in local populations of crustaceans has increased 13 times. A study published in the journal Ecosphere.

The reproduction of biomass in enriched ecosystems is described in the ecological theory of bottom-up (bottom-up). For example, in the lake, the inflow of biogenic elements — phosphorus and nitrogen leads to the growth of microscopic algae. The increase in the mass of phytoplankton leads to the growth of crustaceans, which are food for fish. Thus, the eutrophication of water bodies, that is the enrichment necessary for living organisms, elements, leads to an increase in the number of participants at all levels of the food chain.

Interactions within ecosystems are not limited to model “predator-prey”, they also include parasitism. The authors decided to find out how the influx of nutrients into the lake will affect the number of parasites on the example of flatworms Levinseniella byrdi who “brainwash” their hosts — crustacean Orchestia grillus.

Crustaceans Orchestia are intermediate hosts in the complex cycle of reproduction of the parasite. In order to get to its main owner — the bird — worms it is necessary that the infected shrimp ate it. Infected shrimp instead of hiding in the vegetation, prefer to spend time in the open areas. In addition, the carapace of infected shrimps from green to bright orange. Changes in behavior and bright coloration of the shrimp is convenient not only birds, but researchers, as the infected crustaceans are easy to count.

A testing ground for the study of parasites has served a system of marshy salt lakes area of 60 thousand square meters, where for 11 years, the researchers added nitrogen in the form of nitrate to study the effects of eutrophication of the reservoir (the main results of this work have been published in other articles, including the journal Nature).