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18th November 2023 (10 Topics)

Extreme weather events driving replacement of native species with exotic ones

Context:

As per the recent analysis, it shows higher reproduction, competitiveness and plasticity may be helping non-native species.

Data Source: The findings were recently published in the journal Nature Ecology & Evolution.

Extreme weather events:

  • Extreme weather events are affecting land, marine and freshwater ecosystems by influencing the displacement of native species with non-native ones.
  • The increasing frequency of extreme weather events such as heatwaves, cold waves, droughts and floods due to climate change is influencing ecosystems, said researchers at Chinese Academy of Sciences in Beijing, China.

Impact on Native Species:

  • Biodiversity: The scientists looked at 443 studies and analysed 1,852 native and 187 non-native species residing in land, marine and freshwater habitats and their responses to extreme weather events.
  • Marine Biodiversity: Marine animals overall remained insensitive to extreme weather events, irrespective of whether they were native or non-native, the analysis said. However, native molluscs, corals and anemones showed negative effects due to heatwaves. 
  • Heatwaves and storms: Heatwaves and storms affected non-native species in terrestrial and freshwater habitats, respectively. Native animals responded adversely to heatwaves, droughts and cold spells in terrestrial ecosystems and displayed more vulnerability to extreme weather events. 
  • Non-Native Species: On average, non-native species were less abundant in terrestrial ecosystems and their body conditions and life history traits were affected in freshwater systems.
    • Non-native species had 8 per cent positive, 31.8 per cent negative and 43.4 per cent neutral responses (confidence intervals crossing zero) to extreme weather events.
    • Non-native terrestrial animals were affected only by heatwaves, while their counterparts in freshwater animals showed susceptibility to only storms.
    • Non-native marine animals remained largely unaffected by most disturbances.
  • Native Species: But native animals indicated declines in body conditions, life history traits, abundance, distribution and recovery in terrestrial ecosystems and community structure in freshwater ecosystems.
    • Native species had 7 per cent positive, 20.5 per cent negative and 66.8 per cent neutral responses to extreme weather events.
    • Native terrestrial animals were affected harder by heatwaves, cold spells and drought.
    • Native freshwater species, on the other hand, were vulnerable to most events except cold spells.

High sensitivity of Native animals and low sensitivity of Non-native animals:

  • Severe drought vents: It deceased native invertebrates and fishes by increasing water salinity, facilitating the establishment of non-native salt-tolerant counterparts
  • High growth rate of Invasive species: The non-native or invasive species have higher growth rates, higher phenotypic plasticity, stronger competitive abilities, quicker recovery and proliferation and broader tolerance of disturbance compared to the native species.

Case Study: Rio Minho estuary, Portugal:

  • The abundance of most native fish in the Rio Minho estuary, Portugal declined, but the abundance of non-native fish increased after extreme droughts and floods, and thus the fish assemblage there was dominated by a few invasive fish species after extreme weather events.
  • Non-native mesozooplankton species exhibit higher flexibility to marine heatwaves than native species in the Sevastopol Bay
  •  Case Study: South American tomato pinworm
  • The abundance of the invasive South American tomato pinworm was tolerant of acute and chronic temperature stress because of high thermal plasticity in invaded ranges

 

What is Plasticity?

Plasticity is the capacity of an individual organism to alter its behavior, physiology / gene expression, and / or morphology in direct response to changing environmental conditions.

Way Forward:

Invasive species has both positive an negative impacts on any region, but extreme weather events like storm, droughts, floods, heat waves are making conditions worse for native species where invasive species are able to thrive in the new changing environment. Thus, it is important to understand the biology of native species and collaboration is needed to make a combined effort to save native species for maintaining diverse biodiversity for future.

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