Many Things Can Spread With Unintended Consequences
December 8, 2020 at 9:09 p.m.
By Max [email protected]
There have been a number of other examples that do not include viruses. There have been aquatic species like the Nile perch that exterminated orchid populations in Lake Victoria and caused deforestation. Lionfish are feeding voraciously on reel fish and altering the biological community structure.
Other examples include the Asian Carp – introduced to the U.S. from southeast Asia. These fish are fast-growing, aggressive and adaptable, allowing them to outcompete native fish for food and habitat space. They were originally imported to the U.S. in the 1970s to filter pond water and quickly spread throughout the country both commercially and on their own.
The Zebra Mussel – originally from Eastern Europe – have found their way to the Great Lakes in the 1980s through ballast waters of ocean-going ships. They spread quickly, outcompeting native species for food and habitats. By the start of the 1990s, they populated all of the Great Lakes. In addition to challenging native ecosystems, they also promote the growth and spread of harmful algal blooms.
The European Green Crabs made their way to the San Francisco Bay beginning in 1989 and now outcompete native species for food and habitat and eat lots of native shellfish, threatening commercial fisheries.
Cane toads became pests after being introduced into Australia to control destructive beetles in Queensland’s sugarcane crops. Cane toads are capable of poisoning predators that try to eat them and they continue to spread across Australia. There is no broadscale way to control this pest but scientists are developing a better understanding of the impacts they have on the environment and the ways in which assets, such as rare and vulnerable wildlife, can be protected.
Insects
Insects have also led to serious consequences. Africanized honey bees are one example, they escaped from Brazil and are changing pollenization patterns of tropical rain forests trees while expanding to North America.
Plants
Plant species that have caused devastation include the Water hyacinth. It originated in South America, and made its way to the U.S. as an ornamental. The plant grows quickly and forms dense mats at the water’s surface, reducing available sunlight for submerged plants and aquatic organisms. It also crowds out native plants and clogs waterways and pipes. One of the more interesting species is kudzu a vine-like plant found in the southeastern United States. Time magazine recently called kudzu’s introduction one of the hundred worst ideas of the twentieth century, along with Prohibition, telemarketing, DDT, and the Jerry Springer Show.
Animals
Rats are a prime example and these species have overwhelmed New Zealand. The new arrivals suddenly found wide-open terrain for them to exploit. Rats including Ship, Norway and kiore have a major impact in New Zealand because they are omnivores – eating birds, seeds, snails, lizards, fruit, weta, eggs, chicks, larvae and flowers.
The varied diet of rats also makes them competitors with native wildlife for food sources. Ship rats are found in many different habitats around New Zealand and are widespread in lowland podocarp-broadleaf forests. They are good climbers, so they can access many bird nests high in trees. On offshore islands, Norway rats are large enough to kill burrow-nesting adult seabirds and eat their eggs and chicks.
European wild rabbits are invasive, feral pests throughout much of Australia. They cause considerable damage to the natural environment and to primary production. Rabbits were introduced to Australia in the 1800s by European settlers. Free from diseases and facing relatively few predators in a modified environment, the wild populations grew rapidly. They soon became a problem for colonists trying to establish vegetable gardens and, after the 1860s, quickly spread across two thirds of Australia with devastating impact.
Domesticated European rabbits arrived in Australia with the first fleet. They were introduced for food and wild rabbits were later brought in for hunting. A colony of feral rabbits was reported in Tasmania in 1827 and wild European rabbits were released in Victoria in 1859, and in South Australia shortly after. By 1886 they were found throughout that Victoria and New South Wales – even extending to the Northern Territory by the 1900s. By 1910 feral rabbits were found throughout most of their current range. By 1920 it is thought there were 10 billion rabbits in Australia. The population is currently estimated to be 200 million. Molecular analysis of current populations reveals a patchwork of varying genetics in rabbits with six main regional groupings across the country, further supporting a history of multiple introductions, followed by regional dispersal.
Environmental damage is now the biggest problem caused by feral rabbits in Australia. Feral rabbits compete for feed and shelter with native animals, but most environmental harm comes from how they graze, and because they help maintain feral predators. Rabbits have clearly contributed to the decline or loss of the greater bilby, yellow-footed rock-wallaby, southern and northern hairy-nosed wombats, the malleefowl and the plains-wanderer.
Final Thoughts
In terms of evolutionary biology, the species mentioned have had what is known as an “ecological release.” This refers to the expansion of range and the population explosion that occurs when a species is freed from constraints it previously faced.
Max Sherman is a medical writer and pharmacist retired from the medical device industry. His new book “Science Snippets” is available from Amazon and other book sellers. It contains a number of previously published columns. He can be reached by email at [email protected].
There have been a number of other examples that do not include viruses. There have been aquatic species like the Nile perch that exterminated orchid populations in Lake Victoria and caused deforestation. Lionfish are feeding voraciously on reel fish and altering the biological community structure.
Other examples include the Asian Carp – introduced to the U.S. from southeast Asia. These fish are fast-growing, aggressive and adaptable, allowing them to outcompete native fish for food and habitat space. They were originally imported to the U.S. in the 1970s to filter pond water and quickly spread throughout the country both commercially and on their own.
The Zebra Mussel – originally from Eastern Europe – have found their way to the Great Lakes in the 1980s through ballast waters of ocean-going ships. They spread quickly, outcompeting native species for food and habitats. By the start of the 1990s, they populated all of the Great Lakes. In addition to challenging native ecosystems, they also promote the growth and spread of harmful algal blooms.
The European Green Crabs made their way to the San Francisco Bay beginning in 1989 and now outcompete native species for food and habitat and eat lots of native shellfish, threatening commercial fisheries.
Cane toads became pests after being introduced into Australia to control destructive beetles in Queensland’s sugarcane crops. Cane toads are capable of poisoning predators that try to eat them and they continue to spread across Australia. There is no broadscale way to control this pest but scientists are developing a better understanding of the impacts they have on the environment and the ways in which assets, such as rare and vulnerable wildlife, can be protected.
Insects
Insects have also led to serious consequences. Africanized honey bees are one example, they escaped from Brazil and are changing pollenization patterns of tropical rain forests trees while expanding to North America.
Plants
Plant species that have caused devastation include the Water hyacinth. It originated in South America, and made its way to the U.S. as an ornamental. The plant grows quickly and forms dense mats at the water’s surface, reducing available sunlight for submerged plants and aquatic organisms. It also crowds out native plants and clogs waterways and pipes. One of the more interesting species is kudzu a vine-like plant found in the southeastern United States. Time magazine recently called kudzu’s introduction one of the hundred worst ideas of the twentieth century, along with Prohibition, telemarketing, DDT, and the Jerry Springer Show.
Animals
Rats are a prime example and these species have overwhelmed New Zealand. The new arrivals suddenly found wide-open terrain for them to exploit. Rats including Ship, Norway and kiore have a major impact in New Zealand because they are omnivores – eating birds, seeds, snails, lizards, fruit, weta, eggs, chicks, larvae and flowers.
The varied diet of rats also makes them competitors with native wildlife for food sources. Ship rats are found in many different habitats around New Zealand and are widespread in lowland podocarp-broadleaf forests. They are good climbers, so they can access many bird nests high in trees. On offshore islands, Norway rats are large enough to kill burrow-nesting adult seabirds and eat their eggs and chicks.
European wild rabbits are invasive, feral pests throughout much of Australia. They cause considerable damage to the natural environment and to primary production. Rabbits were introduced to Australia in the 1800s by European settlers. Free from diseases and facing relatively few predators in a modified environment, the wild populations grew rapidly. They soon became a problem for colonists trying to establish vegetable gardens and, after the 1860s, quickly spread across two thirds of Australia with devastating impact.
Domesticated European rabbits arrived in Australia with the first fleet. They were introduced for food and wild rabbits were later brought in for hunting. A colony of feral rabbits was reported in Tasmania in 1827 and wild European rabbits were released in Victoria in 1859, and in South Australia shortly after. By 1886 they were found throughout that Victoria and New South Wales – even extending to the Northern Territory by the 1900s. By 1910 feral rabbits were found throughout most of their current range. By 1920 it is thought there were 10 billion rabbits in Australia. The population is currently estimated to be 200 million. Molecular analysis of current populations reveals a patchwork of varying genetics in rabbits with six main regional groupings across the country, further supporting a history of multiple introductions, followed by regional dispersal.
Environmental damage is now the biggest problem caused by feral rabbits in Australia. Feral rabbits compete for feed and shelter with native animals, but most environmental harm comes from how they graze, and because they help maintain feral predators. Rabbits have clearly contributed to the decline or loss of the greater bilby, yellow-footed rock-wallaby, southern and northern hairy-nosed wombats, the malleefowl and the plains-wanderer.
Final Thoughts
In terms of evolutionary biology, the species mentioned have had what is known as an “ecological release.” This refers to the expansion of range and the population explosion that occurs when a species is freed from constraints it previously faced.
Max Sherman is a medical writer and pharmacist retired from the medical device industry. His new book “Science Snippets” is available from Amazon and other book sellers. It contains a number of previously published columns. He can be reached by email at [email protected].
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