Crayfish and carp “among invasive species pushing lakes to ecosystem collapse”


Crayfish and carp are among the invasive species that are pushing lakes towards ecosystem collapse, researchers have found.

Researchers say some non-native invasive species can quickly disrupt the lake environment – contaminating water for consumption, aquaculture and recreation.

Climate change and human activity are causing these animals to spread rapidly around the world.

Researchers suggest that some invasive species can push lake ecosystems past a critical tipping point, causing a sudden shift from healthy to degraded conditions that are difficult to reverse.

The study found that invasive fish such as Asian silver carp, Hypophthalmichthys molitrix, and crustaceans such as American crayfish, Pacifastacus leniusculus, significantly reduced the abundance of other important organisms in the lakes and degraded the quality of water. ‘water.

The document also provides advice on how to manage water bodies.

Shallow lakes naturally exist in one of two alternate stable states.

They are either healthy – with clear water with abundant vegetation, or degraded – with cloudy water dominated by algae.

When a lake is in the latter state, the algae use up all the nutrients in the water and block sunlight, preventing the growth of aquatic vegetation that would aid ecosystem recovery.

Such conditions also threaten the health and water safety of human populations, scientists say.

Blooms of cyanobacteria, known as “blue-green algae,” can produce toxins that contaminate food webs and poison water supplies.

Dr Sam Reynolds of the Department of Zoology at the University of Cambridge is the first author of the report.

He said: “Algal blooms represent one of the most significant threats to the security of the Earth’s surface freshwater.

“Simply reversing the circumstances that triggered a tipping point will not restore the ecosystem – the road to recovery is slow and steep.”

However, while invasive species are recognized as a significant threat to global biodiversity, researchers say their impacts on ecosystem services may not all be negative.

Invasive molluscs, including the zebra mussel Dreissena polymorpha, have been shown to engineer the opposite biological and environmental response.

They delay ecosystem collapse and could potentially help reestablish degraded lake ecosystems.

Professor David Aldridge, lead author of the report, said: “Managers of drinking water reservoirs, for example, can avoid the costs associated with harmful algal blooms, by eliminating invasive crayfish but allowing zebra mussels to remain unaffected. established natives remain and act as biological filters.

He added: “Early detection and rapid response plans should always be our first line of attack.

“But in situations where the invaders have already established themselves and can no longer be eradicated, it may be appropriate to embrace their positive effects.”

Researchers systematically compiled data from 418 observations in 101 studies.

They focused on shallow lake ecosystems, but say their framework could be applied to other critical ecosystems that are experiencing catastrophic tipping points – such as coral reefs, kelp forests and desert scrub.

Funded by the Biotechnology and Biological Sciences Research Council (BBSRC), the research is published in the journal Global Change Biology.

Press Association


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