Female signal crayfish. Credit: Astacoides/CC BY-SA 3.0/ Wikimedia
A new study shows that certain non-native invasive species can cause lake disruptions to the point where they lead to rapid ecosystem collapse. This could result in water contamination for aquaculture, drinking and recreation.
Climate change and human activity are both causing non-native invasive species to rapidly spread across the globe. Researchers discovered that some invasive species can cause lake ecosystems to shift rapidly from healthy to unhealthy. This is hard to reverse.
Asian silver carp Hypophthalmichthys Molitrix and crustaceans Pacifastacus Leniusculus, which are invasive fish, have been shown to reduce water quality and increase the abundance of important organisms in lakes. These findings were published in the journal Global Change Biology today and offer guidance on how to best manage waterbodies.
Two types of shallow lakes can exist naturally: healthy with clear water and abundant vegetation or unhealthy with cloudy, algae-dominated water. Algae can eat up all nutrients in the lake and block sunlight from the surface, which prevents the growth of aquatic vegetation. This is a bad state for ecosystem recovery.
Alga-dominated freshwater ecosystems can also pose a threat to the water security and health of humans. The toxins produced by cyanobacteria blooms, also known as "blue-green alga", can contaminate food webs or poison water supplies.
"Algal Blooms are one of the greatest threats to the security and availability of Earth's surface freshwaters. It is not possible to reverse the events that led to a tipping point. The road to recovery is long and difficult," stated Dr. Sam Reynolds, first author of this report.
Although invasive species pose a threat to biodiversity worldwide, they may not have a negative impact on ecosystem services. Invasive molluscs such as the Dreissena polymorpha zebra mussel, have been shown to cause the opposite of the expected biological and environmental responses. They delay ecosystem collapse and can help in the recovery and maintenance of lake ecosystems.
Professor David Aldridge, senior author, said that managers of drinking water reservoirs may be able avoid dealing with blooms. He suggested that they remove invasive crayfish, but allow non-native zebra mustels to remain as biological filters.
He said, "Early detection should be our first line attack. Rapid response plans should also be our first choice." In situations where intruders are already established and cannot be eradicated, however, it might be wise to accept their positive effects.
Although the research was limited to shallow lakes ecosystems, it is possible to apply their framework to other critical ecosystems such as desert shrublands, coral reefs, and kelp forests.
Learn more. Clear lakes around the world are being threatened by attached algal blooms
Reynolds, S. A. for more information. Aldridge, D. C. : Global impacts of invasive species upon the tipping points for shallow lakes. Global Change Biology, October 2021. DOI: 10.1111/gcb.15893 Journal Information: Global Change Biology Reynolds S. A. & Aldridge D. C.: Global effects of invasive species upon the tipping point of shallow lakes. October 2021. DOI: 10.1111/gcb.15893
