New MAISRC research shows invasive common carp more damaging to biodiversity than human development
New, first-of-its-kind research from MAISRC is adding to the evidence that biological invaders – such as zebra mussels, rusty crayfish, and Asian carp – are threatening to be the main driver of biodiversity and ecosystem function loss in lakes in the 21st century.
Because many of these invasions are relatively new, their impacts are not always readily apparent. The impacts can also be confounded with those caused by other stressors. That is why this team of researchers – led by Dr. Przemek Bajer – focused on the century-old invasion of common carp to illustrate the potential consequences of introducing non-native ecosystem engineers to lakes worldwide.
They found that when common carp were prolific, plant cover was reduced to less than 10% and species biodiversity was halved. By teasing out the impacts of other human-caused stressors, this research also revealed that carp had a greater impact on aquatic plant biodiversity than human watershed development did.
"Understanding the importance of biological invasions relative to other stressors is highly important to ecologists, policymakers, and lake managers," said Dr. Bajer. "By showing that invasive species are such an important driver of ecosystem change, this research demonstrates the value of curbing introductions of these and other non-native species."
For the study, researchers analyzed data from over 2,000 Minnesota lakes, covering our three major ecoregions of Great Plains, Eastern Temperate Forests, and Northern Forests. They also conducted whole lake experiments in six lakes in which they established what the current carp populations were, surveyed plant cover, and identified species richness both before and after removing carp. All four study lakes (two served as controls) showed that removing common carp increased plant cover, species richness, and water clarity. To evaluate the contributions from human development, the team used the proportion of land used by humans for urban developments and agriculture within the watersheds. They then used statistical models to determine which variable caused the most impact.
Common carp are known for increasing water turbidity and uprooting aquatic plants while searching for food in the sediment. The associated loss of plant cover and biodiversity can have a cascading effect on the abundance and diversity of waterfowl, insects, and amphibians and can hinder fundamental ecosystem functions such as maintaining water clarity, reducing erosion, and sequestering nutrients. Learn more about common carp here.
