Biological Invasions
Many kinds of marine organisms in coastal waters are transferred from one region to another around the world in the ballast water of ships. Ballast water is seawater pumped into the tanks and cargo holds of ships to give them better stability. Ballast water is usually taken on when a ship has delivered cargo to a port and is leaving with less cargo or no cargo. It is released at the next port where the ship picks up more cargo. Thousands of marine species are carried around the world in ballast water every day.
Typically, very few of these foreign invaders will survive in their new surroundings. However, some encounter conditions that allow them to become well established and sometimes overwhelm the natural marine community in the area. This may be because the invader lacks the natural predators. pathogens, or parasites in its new location that would normally keep its numbers in check. Or it may encounter an unusually abundant food supply or be able to out compete native species for available food and habitat space.Examples of introduced marine organisms are myriad and include seaweeds. jellyfish. sea stars, and many others.
The introduction of a jellyfish-like animal, a species of comb jelly.Mnemiopsis leidyi. from the coastal waters of North America into the Black Sea in ballast water in the 1980s illustrates very well the devastation that can be caused by marine invaders. This animal quickly multiplied to plaque numbers in the predator-free environment of the Black Sea, voraciously consuming the natural zooplankton in the sea, including the eggs and juvenile stages of fish. Fish stocks collapsed by the early 1990s, causing great economic loss to the region, and dolphins, which fed on these fish.disappeared. Interestingly, it took the invasion of another exotic species of comb jelly, Beroeovata, also in ballast water, to alleviate this ecological disaster in the Black Sea. Around 1997, this species began to thrive in the Black Sea, feeding heavily on the first foreign invader, causing a steep reduction in its numbers. The Beroeovata population then collapsed as it exhausted its food supply.Since then, fish stocks have begun to recover and dolphins have returned.
Once well established, many foreign invaders are impossible to eradicate. Attempts have been made to control the spread of the Japanese sea star, Asterias amurensis-which has eliminated many native bottom-dwelling organisms in Australian ports since its introduction in the mid-1990s-by recruiting divers to remove the animals by hand, and also by trapping or dredging the sea stars.They have also been commercially harvested and converted into fertilizer. But none of this has had much success in restoring the natural marine system of the area. Efforts are now focused on limiting the spread of the species through an education campaign that encourages reporting of local sightings, which is followed up by a rapid eradication program. There is fear that the species could spread to New Zealand. and legislation has been passed in that country preventing the discharge in New Zealand ports of ballast water that has been taken from ports in Australia where this sea star is now found. This is to reduce the chance of introduction of the species into New Zealand in its larval form.
International efforts are now being made to limit the spread of exotic marine species in ballast water. Ships are now meant to empty and then refill their ballast tanks in the open ocean before arriving at a port. The reasoning behind this is that the ballast-water hitchhikers taken up in port will be released into the open ocean, where they cannot survive, and the planktonic organisms taken up in the open ocean will be released into the coastal waters of the next port, where conditions will not be suitable for their survival Unfortunately, not all ships follow this procedure, and ballast water cannot be safely exchanged in the open ocean during rough weather. Thus, some port authorities are considering developing procedures to sterilize a ship’s ballast water before it is pumped out or to pass the ballast water through a treatment facility on shore before its discharge into the natural environment.
1
Many kinds of marine organisms in coastal waters are transferred from one region to another around the world in the ballast water of ships. Ballast water is seawater pumped into the tanks and cargo holds of ships to give them better stability. Ballast water is usually taken on when a ship has delivered cargo to a port and is leaving with less cargo or no cargo. It is released at the next port where the ship picks up more cargo. Thousands of marine species are carried around the world in ballast water every day.
According to paragraph 1, which of the following is NOT true of ballast water?
AIt is used as a means of transporting marine cargo, such as live fish.
BIt is responsible for transferring thousands of marine animals around the world.
CIt is used to stabilize ships, especially when they are empty or partially empty.
DIt is typically taken on in one port and discharged in another.
2
Typically, very few of these foreign invaders will survive in their new surroundings. However, some encounter conditions that allow them to become well established and sometimes overwhelm the natural marine community in the area. This may be because the invader lacks the natural predators. pathogens, or parasites in its new location that would normally keep its numbers in check. Or it may encounter an unusually abundant food supply or be able to out compete native species for available food and habitat space.Examples of introduced marine organisms are myriad and include seaweeds. jellyfish. sea stars, and many others.
In stating that examples of introduced organisms “are myriad,” the author means that the examples
Ashare certain characteristics
Bare great in number
Care well known
Dcan be identified easily
3
The introduction of a jellyfish-like animal, a species of comb jelly.Mnemiopsis leidyi. from the coastal waters of North America into the Black Sea in ballast water in the 1980s illustrates very well the devastation that can be caused by marine invaders.
Which of the sentences below best expresses the essential information in the highlighted sentence in the passage?Incorrect choices change the meaning in important ways or leave out essential information.
AIn the 1980s, a jellyfish-like animal called a comb jelly was introduced into the coastal waters of the Black Sea
BA species of comb jelly, Mnemiopsis leidyi , caused devastation from the coastal waters of North America to the Black Sea.
CIn the 1980s, the population of the comb jelly Mnemiopsis leidyi was devastated by marine invaders from North America.
DMarine invaders can be devastating, as shown by the introduction of the comb jelly Mnemiopsis leidyi to the Black Sea.
4
The introduction of a jellyfish-like animal, a species of comb jelly.Mnemiopsis leidyi. from the coastal waters of North America into the Black Sea in ballast water in the 1980s illustrates very well the devastation that can be caused by marine invaders. This animal quickly multiplied to plaque numbers in the predator-free environment of the Black Sea, voraciously consuming the natural zooplankton in the sea, including the eggs and juvenile stages of fish. Fish stocks collapsed by the early 1990s, causing great economic loss to the region, and dolphins, which fed on these fish.disappeared. Interestingly, it took the invasion of another exotic species of comb jelly, Beroeovata, also in ballast water, to alleviate this ecological disaster in the Black Sea. Around 1997, this species began to thrive in the Black Sea, feeding heavily on the first foreign invader, causing a steep reduction in its numbers. The Beroeovata population then collapsed as it exhausted its food supply.Since then, fish stocks have begun to recover and dolphins have returned.
According to paragraph 3, what happened after the comb jelly Beroe ovata was introduced to the Black Sea?
AIt became permanently established in the region.
BIt eliminated a more problematic foreign invader.
CIt caused an ecological disaster.
DIts population growth was controlled by dolphins and local fish.
5
Once well established, many foreign invaders are impossible to eradicate. Attempts have been made to control the spread of the Japanese sea star, Asterias amurensis-which has eliminated many native bottom-dwelling organisms in Australian ports since its introduction in the mid-1990s-by recruiting divers to remove the animals by hand, and also by trapping or dredging the sea stars.They have also been commercially harvested and converted into fertilizer. But none of this has had much success in restoring the natural marine system of the area. Efforts are now focused on limiting the spread of the species through an education campaign that encourages reporting of local sightings, which is followed up by a rapid eradication program. There is fear that the species could spread to New Zealand. and legislation has been passed in that country preventing the discharge in New Zealand ports of ballast water that has been taken from ports in Australia where this sea star is now found. This is to reduce the chance of introduction of the species into New Zealand in its larval form.
Why does the author provide the information that the Japanese sea star. Asterias amurensis has been “commercially harvested and converted into fertilizer?
ATo argue that invasive species do not always have negative effects on a region’s economy
BTo provide an example of one of the many uses for this species of sea star
CTo explain what happens to sea stars after they are collected by diving or dredging
DTo provide an example of an attempt to control invaders that has not been successful
6
Once well established, many foreign invaders are impossible to eradicate. Attempts have been made to control the spread of the Japanese sea star, Asterias amurensis-which has eliminated many native bottom-dwelling organisms in Australian ports since its introduction in the mid-1990s-by recruiting divers to remove the animals by hand, and also by trapping or dredging the sea stars.They have also been commercially harvested and converted into fertilizer. But none of this has had much success in restoring the natural marine system of the area. Efforts are now focused on limiting the spread of the species through an education campaign that encourages reporting of local sightings, which is followed up by a rapid eradication program. There is fear that the species could spread to New Zealand. and legislation has been passed in that country preventing the discharge in New Zealand ports of ballast water that has been taken from ports in Australia where this sea star is now found. This is to reduce the chance of introduction of the species into New Zealand in its larval form.
According to paragraph 4, what measures have been taken in New Zealand to prevent the spread of Japanese sea stars to its ports?
AAn education campaign has been implemented to encourage reporting of local sightings.
BA rapid-elimination program has been implemented to remove any early signs of the sea stars.
CA law has been passed forbidding the release of ballast water from ports infested with sea stars.
DA test has been developed to detect whether or not the larval form of the species is present in ballast water
7
International efforts are now being made to limit the spread of exotic marine species in ballast water. Ships are now meant to empty and then refill their ballast tanks in the open ocean before arriving at a port. The reasoning behind this is that the ballast-water hitchhikers taken up in port will be released into the open ocean, where they cannot survive, and the planktonic organisms taken up in the open ocean will be released into the coastal waters of the next port, where conditions will not be suitable for their survival Unfortunately, not all ships follow this procedure, and ballast water cannot be safely exchanged in the open ocean during rough weather. Thus, some port authorities are considering developing procedures to sterilize a ship’s ballast water before it is pumped out or to pass the ballast water through a treatment facility on shore before its discharge into the natural environment.
The word “exotic’ in the passage is closest in meaning to
AForeign
Baggressive
Cdangerous
Dcompetitive
8
International efforts are now being made to limit the spread of exotic marine species in ballast water. Ships are now meant to empty and then refill their ballast tanks in the open ocean before arriving at a port. The reasoning behind this is that the ballast-water hitchhikers taken up in port will be released into the open ocean, where they cannot survive, and the planktonic organisms taken up in the open ocean will be released into the coastal waters of the next port, where conditions will not be suitable for their survival Unfortunately, not all ships follow this procedure, and ballast water cannot be safely exchanged in the open ocean during rough weather. Thus, some port authorities are considering developing procedures to sterilize a ship’s ballast water before it is pumped out or to pass the ballast water through a treatment facility on shore before its discharge into the natural environment.
What does paragraph 5 suggest is the reason why ballast water from the open ocean is preferred to water from another port?
AOrganisms taken up in the open ocean and locked in ballast tanks lack the food they need to survive until they reach a coastal area.
BPlanktonic organisms in the open ocean are generally the same species as planktonic organisms in nearby ports.
CThe environments of the open ocean and coastal ports differ so much that organisms from one environment are unable to survive when they are transported to the other
DOrganisms collected in the open ocean near a port do not have time to reproduce in the ballast tanks and thus are less likely to become a problem.
9
The introduction of a jellyfish-like animal, a species of comb jelly.Mnemiopsis leidyi. from the coastal waters of North America into the Black Sea in ballast water in the 1980s illustrates very well the devastation that can be caused by marine invaders. This animal quickly multiplied to plaque numbers in the predator-free environment of the Black Sea, voraciously consuming the natural zooplankton in the sea, including the eggs and juvenile stages of fish. Fish stocks collapsed by the early 1990s, causing great economic loss to the region, and dolphins, which fed on these fish.disappeared. Interestingly, it took the invasion of another exotic species of comb jelly, Beroeovata, also in ballast water, to alleviate this ecological disaster in the Black Sea. Around 1997, this species began to thrive in the Black Sea, feeding heavily on the first foreign invader, causing a steep reduction in its numbers. The Beroeovata population then collapsed as it exhausted its food supply.[■] Since then, fish stocks have begun to recover and dolphins have returned.
[■] Once well established, many foreign invaders are impossible to eradicate.[■] Attempts have been made to control the spread of the Japanese sea star, Asterias amurensis-which has eliminated many native bottom-dwelling organisms in Australian ports since its introduction in the mid-1990s-by recruiting divers to remove the animals by hand, and also by trapping or dredging the sea stars.[■] They have also been commercially harvested and converted into fertilizer. But none of this has had much success in restoring the natural marine system of the area. Efforts are now focused on limiting the spread of the species through an education campaign that encourages reporting of local sightings, which is followed up by a rapid eradication program. There is fear that the species could spread to New Zealand. and legislation has been passed in that country preventing the discharge in New Zealand ports of ballast water that has been taken from ports in Australia where this sea star is now found. This is to reduce the chance of introduction of the species into New Zealand in its larval form.
Look at the four squaresthat indicate where the following sentence could be added to the passage
Such a fortunate outcome, however, is very unusual.
Where would the sentence best fit？Click on a square sentence to the passage.
10
Thousands of marine species, including seaweeds, jellyfish, sea stars, and many others are carried around the world in ballast water.
AIf a coastal invader encounters plentiful food and a habitat without predators or pathogens, its population may explode, destroying much of the local marine community.
BTo limit the spread of invasive marine animals, ships are supposed to empty and refill their ballast tanks in the open ocean, and in the future may sterilize or treat ballast water before its release
Clntroduced species are sometimes harmless or even beneficial to the local marine community, as was the case with the Mnemiopsis leidyi.which provided needed food for zooplankton and dolphins
DAlthough rare, established invaders can be extremely harmful economically as well as biologically, and efforts to eliminate them are.often ineffective, despite being labor-intensive and expensive.
EA common strategy to deal with invasive species is to deliberately introduce a natural predator of the invader, as was done to eliminate a plague of Beroe ovata comb jellies in the Black Sea.
FJapanese sea stars have spread across New Zealand’s coasts, and there is fear that they may reach other ports in Australia if legislation to contain them is not passed.
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