Seasonal dynamics of phenolic substances from the macrophyte Myriophyllum aquaticum and their allelopathic effects on the growth and reproduction of Plationus patulus (Rotifera: Brachionidae)

We studied temporal variations in phenolic compounds from the hydrophyte Myriophyllum aquaticum collected from a shallow lake. The effects of macrophyte-conditioned medium containing phenols with other compounds and phenols only as well as plant tissue extracts were tested on the survival and reproduction of the rotifer Plationus patulus. Apical tissue of the hydrophyte had the highest levels of total phenols. Rotifers in controls, and those exposed to phenols from the macrophyte-conditioned medium grew rapidly within two weeks, but cultures exposed to phenols extracted from the apical region took longer. Age-specific survival of P. patulus showed a rapid decline within one week when exposed to plant extracts compared to conditioned medium. The average lifespan of P. patulus was longer in the macrophyte-conditioned medium as compared to the controls, but shorter in the aqueous plant extract. Gross and net reproductive rates showed similar trends, wherein the controls had significantly higher values than those exposed to plant extracts, but increased with the conditioned medium only at the two lower concentrations tested. The demographic response of rotifers exposed to phenols only from the macrophyte-conditioned medium differed from those of the macrophyte-conditioned medium containing both phenolic and non-phenolic compounds. Macrophyte phenolic compounds influenced the survival and reproduction of P. patulus but depended on the other chemicals released into the medium.

Automated summary

In this study, we investigated the effects of phenolic compounds from hydrophytes on the survival and reproduction of rotifers. The results showed that these compounds influenced the age-specific survival, lifespan, and reproductive rates of the rotifers, but their effects depended on other chemicals released into the medium.