Climate Warming and Eutrophication Exert Synergistic Effects on Zooplankton Predator–Prey Interactions

Warming mesocosms facility (Image by IHB)

The research group led by Prof. XU Jun from the Institute of Hydrobiology (IHB) of the Chinese Academy of Sciences revealed that climate warming and eutrophication exert synergistic effects on zooplankton predator–prey interactions and lead to a decline in abundance of herbivory zooplankton in shallow lakes. The study was published in Global Change Biology. 

A growing body of literature suggests that climate change and other co-occurring large-scale environment changes such as eutrophication, can have a considerable impact on aquatic communities and trophic interactions. However, the interactions of these environmental changes on trophic interactions among zooplankton remain largely unknown.

In this study, the researchers conducted a long-term mesocosm experiments in which they evaluated the individual and interactive of climate warming and eutrophication on the recruitment and abundance of zooplankton from a natural community. 

Warming and eutrophication treatments were set based on the future levels predicted regionally for these variables and temperature was regulated automatically by computer systems.

They found that eutrophication alone weakened the top-down effects exerted by the predator cyclopoid copepods on their rotifer prey.

Then, the researchers analyzed the recruitment and abundance of the couple of predator and prey and evaluated the abundance of the larvae stage of the predator (nauplii).

The results showed that warming not only advanced the recruitment and reproduction of the predator cyclopoid copepods, but also increased the reproduction, imposing a stronger feeding pressure on their rotifer prey. Therefore, warming strengthened the top-down effects of the predator cyclopoid copepods on their prey.

By analyzing the effect size and interactive effect, the researchers found striking synergistic effects of eutrophication and warming on this couple of predator and prey. Thus, in a future climate warming and eutrophication scenario, the predator likely benefitted more from the combination of phosphorus addition and warming, the rotifer prey, on the other hand, will likely suffer from an even higher predation pressure.

The findings suggested that the potential interactive effects of temperature and eutrophication on predator–prey interaction in zooplankton might increase phytoplankton blooms through trophic cascading effects.

This study is crucial for lake management and restoration given future challenges caused by climate warming and eutrophication.