Get to know the invasive alien species that affect biodiversity

Published December 6, 2022, 7:28 PM

by Alexa Basa

  • Water hyacinth, softshell turtle, squirrel are some of the ‘invasive alien species’ that are in the country.
  • They are thriving in places not their natural habitats and are outcompeting native species. When unaddressed, these species will affect have a negative effect on our biodiversity.
  • Many introductions of these species have been made for horticulture, food production, reforestation, and recreation purposes, according to National Invasive Species Strategy and Action Plan (2016-2026).
  • These invasions have been observed in the country’s wetlands, agricultural areas, protected areas, and production and protection forests.

Have you seen a water hyacinth, an aquatic plant with a spongy and inflated leafstalk and purple flower, floating in waterways?

How about a Chinese softshell turtle that appeared in central and southern parts of Luzon or a Finlayson’s squirrel around Metro Manila?

These are some of the invasive alien species found in the Philippines, thriving in places not their natural habitats and outcompeting our native species. When unaddressed, these species will affect our biodiversity negatively.

CHINESE SOFTSHELL turtle is an invasive alien species prevalent in Metro Manila, especially in places with extensive vegetation or crops. (Photo by Department of Environment and Natural Resources)

Invasive alien species, as defined by the Department of Environment and Natural Resources (DENR), are “species introduced deliberately or unintentionally outside their natural habitats where they have the ability to establish themselves, invade, outcompete native species, and take over the new environment.”

According to Convention on Biological Diversity, the invasion of alien species can happen to various taxonomic groups like plants, animals, fungi, and microorganisms, and affect ecosystems.

Invasive alien species are characterized by “rapid reproduction and growth, high dispersal ability, phenotypic plasticity (ability to adapt physiologically to new conditions), and ability to survive on various food types and in a wide range of environmental conditions.”

It added that alien species invasions are likely to occur in native ecosystems disturbed by humans since there is less competition from native species.

Many previous and present introductions of these species have been made for horticulture, food production, reforestation, and recreation purposes, according to National Invasive Species Strategy and Action Plan (2016-2026).

Alien species invasions in the country were a result of the “transport of organisms to a new habitat – this could be between islands within a country or between countries; establishment and propagation of the alien species in the new habitat–either in natural or manmade habitats, such as enclosures, lakes, reforestation areas, and gardens; and uncontrolled spread from [the] initial population over [a] large area–either through deliberate release or accidental escape.”

These invasions have been observed in the country’s wetlands, agricultural areas, protected areas, and production and protection forests; however, the majority of the reports is only anecdotal and has not been scientifically studied.

In addition, there is only a very limited understanding of the effects of invasive alien species on the Philippine native biota.

Some invasive alien species in the country are Finlayson’s squirrels, Chinese softshell turtles, and water hyacinths.

Finlayson’s squirrels, with the scientific name Callosciurus finlaysonii, are rodents native to Southeast Asian countries such as Vietnam, Cambodia, Lao PDR, Myanmar, and Thailand. They have become prevalent in Metro Manila, especially in places with extensive tree vegetation or crops.

These squirrels eat fruits like banana, lanzones, durian, santol, duhat, and mango; vegetables like patola and patani; and young coconut shoots. They were also observed to attack eggs and hatchlings of birds, destroy properties, and are linked to pathogenic microorganisms that could affect human and animal health.

Chinese softshell turtles, scientifically known as Pelodiscus sinensis, have been found in specific wetlands and other places in the country, including those used for aquaculture. They have large populations in Pampanga and are likely to grow in Bulacan, Laguna, Mindoro, Nueva Ecija, and Rizal.

WATER HYACINTH, an aquatic plant with spongy leafstalk and purple flower, is an invasive alien species native to tropical South America. (Photo by Stefan Schweihofer via Pixabay)

Overpopulation of these turtles potentially threatens endemic and indigenous fishes in the country, including local fishponds and fishery operations.

Water hyacinths, or Eichhornia crassipes, are floating aquatic plants native to tropical South America. They were introduced in the country as ornamentals but became a problem to the country over the years.

Some of their impacts are obstruction of waterways, restriction of boat traffic, navigation and recreational activities, severe damage to fish pens and cages, and blocking sunlight and oxygen from reaching water columns and underwater plants.

DENR Sec. Maria Antonia Yulo-Loyzaga, Secretary of the Department of Environment and Natural recently called lawmakers to include invasive alien species and other threats to biodiversity in strengthening the Wildlife Resources Conservation and Protection Act or Republic Act No. 9147.

“It is high time to address the threats to biodiversity such as the proliferation of invasive alien species, destruction of natural habitats, unsustainable utilization of resources, illegal wildlife trade, and environmental pollution,” Loyzaga said.

Senate Bill No. 125, filed by Sen. Cynthia Villar in July 2022, included control and management mechanisms of invasive alien species in the bill, which sought to amend the 21-year-old law.

 
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