Temporary Pools

Temporary pools are freshwater habitats that retain water for only three to four months of the year or even shorter periods: typically for some eight or nine months they are dry basins without surface water.At the latitude of Canada’s southern Ontario,for example,the basin of a typical temporary pool fills with water when snow melts in March and April.Because temporary pools (by definition)have neither a surface inlet nor outlet,the water steadily recedes through evaporation and seepage into the surrounding soil, disappearing altogether from the surface in June or July.Most of the animal residents one sees in temporary pools are aquatic insects such as caddis flies,whose larvae (wingless,immature insects)are sometimes the most conspicuous animals in these communities.

At least two advantages to living in this type of habitat can be recognized.One involves predation.Fish are major predators of aquatic insects and other small freshwater creatures;however fish, at least in temperate regions over much of North America,are unable to survive the dry phase,and hence are eliminated from temporary pools.Predatory insects such as aquatic beetles and bugs and dragonfly nymphs do live in temporary pools,but there are far fewer species,and therefore a less efficient predator population than in permanent waters.Moreover,populations of the invertebrate predators in temporary pools have to develop anew every year from colonizing adults or from drought-resistant eggs.All of this means that the impact of predation is reduced for aquatic animals that have adaptations to survive the dry phase of temporary pools.

A second advantage is concerned with nutrition and growth. Temporary pools,especially in wooded sites,are fuelled primarily by the energy and nutrients stored in fallen leaves and other decomposing plant detritus (nonliving matter that originates from plants).Furthermore,the dry phase of temporary pools usually supports a community of specialized herbaceous plants that can tolerate springtime flooding but grow rapidly in the moist, organically enriched soil after surface water disappears.These plants contribute to the detrital base every year.Although the food web is based mainly on detritus,the processes of decomposition in temporary pools are somewhat different from those in the detritus- based communities of streams and the shore zones of lakes. Detritus decomposes faster when exposed to air during dry periods and has a higher protein content upon flooding in spring than when submerged continuously in permanent water.The reason for this difference is that the terrestrial fungi causing the decomposition of plant detritus in the absence of surface water flourish where oxygen is not limited.In permanent waters,where detrital materials are covered by water,oxygen is not plentiful and decomposition is brought about by aquatic fungi and bacteria,which do not grow as abundantly as terrestrial fungi.Colonizing terrestrial fungi contribute much of the protein of decomposing plant materials,and in feeding experiments limnephilid caddis fly larvae of temporary pools showed a preference for decaying leaves with higher protein levels. Consequently,rapid development,which is so important to animals in transient waters,would be enhanced by the protein-rich detritus as well as by the higher summer temperatures of small bodies of water.

These principles have led to some practical applications.An increase in productivity following a dry phase underlies the practice in wetland management of alternately draining and flooding wetlands.Aquatic birds such as ducks feed on larval caddis flies and other aquatic invertebrates and also on plants;the increased nutrient levels resulting from exposure of more of the bottom detritus to air and terrestrial fungi enhance productivity throughout the food web.By the seventeenth century,fish farmers in Europe had learned that periodically leaving ponds dry and empty of fish yielded higher productivity in controlled ponds of carp fish than did constant water levels.Through manipulation of water levels,the ponds were wintered as dry basins and periodically over a full year as well-practices that led to increased production of fish.In retrospect then,it appears that after centuries of experimentation to increase productivity in marshes and fish ponds,humans succeeded in duplicating the natural cycle of temporary pools.

 

 

1

Temporary pools are freshwater habitats that retain water for only three to four months of the year or even shorter periods: typically for some eight or nine months they are dry basins without surface water.At the latitude of Canada’s southern Ontario,for example,the basin of a typical temporary pool fills with water when snow melts in March and April.Because temporary pools (by definition)have neither a surface inlet nor outlet,the water steadily recedes through evaporation and seepage into the surrounding soil, disappearing altogether from the surface in June or July.Most of the animal residents one sees in temporary pools are aquatic insects such as caddis flies,whose larvae (wingless,immature insects)are sometimes the most conspicuous animals in these communities.

The word“conspicuous”in the passage is closest in meaning to

Aactive

Bdestructive

Clong-lived

Dnoticeable

 

2

At least two advantages to living in this type of habitat can be recognized.One involves predation.Fish are major predators of aquatic insects and other small freshwater creatures;however fish, at least in temperate regions over much of North America,are unable to survive the dry phase,and hence are eliminated from temporary pools.Predatory insects such as aquatic beetles and bugs and dragonfly nymphs do live in temporary pools,but there are far fewer species,and therefore a less efficient predator population than in permanent waters.Moreover,populations of the invertebrate predators in temporary pools have to develop anew every year from colonizing adults or from drought-resistant eggs.All of this means that the impact of predation is reduced for aquatic animals that have adaptations to survive the dry phase of temporary pools.

Why does the author mention that fish“are unable to survive the dry phase”in temporary pools over much of North America?

ATo explain why predatory insects such as aquatic beetles and bugs and dragonfly nymphs are attracted to temporary pools

BTo make the point that temporary ponds are more advantageous for predatory insects than for fish

CTo explain why the population of fish in temporary pools must be replaced each year

DTo give one reason why small creatures in temporary pools experience relatively little predation

 

3

At least two advantages to living in this type of habitat can be recognized.One involves predation.Fish are major predators of aquatic insects and other small freshwater creatures;however fish, at least in temperate regions over much of North America,are unable to survive the dry phase,and hence are eliminated from temporary pools.Predatory insects such as aquatic beetles and bugs and dragonfly nymphs do live in temporary pools,but there are far fewer species,and therefore a less efficient predator population than in permanent waters.Moreover,populations of the invertebrate predators in temporary pools have to develop anew every year from colonizing adults or from drought-resistant eggs.All of this means that the impact of predation is reduced for aquatic animals that have adaptations to survive the dry phase of temporary pools.

Paragraph 2 suggests that predatory insects in permanent waters are likely to

Alive mainly in temperate regions in North America

Bbe more numerous and efficient than predatory insects in temporary pools

Csend groups of colonizing adults to new areas each year

Dhave adaptations that prevent aquatic animals from eating them

 

4

A second advantage is concerned with nutrition and growth. Temporary pools,especially in wooded sites,are fuelled primarily by the energy and nutrients stored in fallen leaves and other decomposing plant detritus (nonliving matter that originates from plants).Furthermore,the dry phase of temporary pools usually supports a community of specialized herbaceous plants that can tolerate springtime flooding but grow rapidly in the moist, organically enriched soil after surface water disappears.These plants contribute to the detrital base every year.Although the food web is based mainly on detritus,the processes of decomposition in temporary pools are somewhat different from those in the detritus- based communities of streams and the shore zones of lakes. Detritus decomposes faster when exposed to air during dry periods and has a higher protein content upon flooding in spring than when submerged continuously in permanent water.The reason for this difference is that the terrestrial fungi causing the decomposition of plant detritus in the absence of surface water flourish where oxygen is not limited.In permanent waters,where detrital materials are covered by water,oxygen is not plentiful and decomposition is brought about by aquatic fungi and bacteria,which do not grow as abundantly as terrestrial fungi.Colonizing terrestrial fungi contribute much of the protein of decomposing plant materials,and in feeding experiments limnephilid caddis fly larvae of temporary pools showed a preference for decaying leaves with higher protein levels. Consequently,rapid development,which is so important to animals in transient waters,would be enhanced by the protein-rich detritus as well as by the higher summer temperatures of small bodies of water.

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.

AAs a result,protein-rich detritus develops rapidly in the high summer temperatures of smaller bodies of water,helping transient animals.

BAs a result,the rapid development of protein-rich detritus improves animals’ability to survive the higher summer temperatures of small bodies of water.

CAs a result,in smaller pools of water,where faster development is important,higher temperatures and protein-rich detritus help animals to develop quickly.

DAs a result,the rapid development of animals in transient waters would enhance the protein-rich detritus of these smaller bodies of water.

 

5

A second advantage is concerned with nutrition and growth. Temporary pools,especially in wooded sites,are fuelled primarily by the energy and nutrients stored in fallen leaves and other decomposing plant detritus (nonliving matter that originates from plants).Furthermore,the dry phase of temporary pools usually supports a community of specialized herbaceous plants that can tolerate springtime flooding but grow rapidly in the moist, organically enriched soil after surface water disappears.These plants contribute to the detrital base every year.Although the food web is based mainly on detritus,the processes of decomposition in temporary pools are somewhat different from those in the detritus- based communities of streams and the shore zones of lakes. Detritus decomposes faster when exposed to air during dry periods and has a higher protein content upon flooding in spring than when submerged continuously in permanent water.The reason for this difference is that the terrestrial fungi causing the decomposition of plant detritus in the absence of surface water flourish where oxygen is not limited.In permanent waters,where detrital materials are covered by water,oxygen is not plentiful and decomposition is brought about by aquatic fungi and bacteria,which do not grow as abundantly as terrestrial fungi.Colonizing terrestrial fungi contribute much of the protein of decomposing plant materials,and in feeding experiments limnephilid caddis fly larvae of temporary pools showed a preference for decaying leaves with higher protein levels. Consequently,rapid development,which is so important to animals in transient waters,would be enhanced by the protein-rich detritus as well as by the higher summer temperatures of small bodies of water.

Paragraph 3 suggests that decomposition happens faster in temporary pools than in permanent water because

Athe specialized plants in temporary pools are easier for fungi to process

Bthe high protein content of detritus in temporary pools attracts fungi

Cthe higher oxygen levels of dry temporary pools allow more fungi to grow

Dthe detrital materials covered by permanent water cannot support fungi

 

6

A second advantage is concerned with nutrition and growth. Temporary pools,especially in wooded sites,are fuelled primarily by the energy and nutrients stored in fallen leaves and other decomposing plant detritus (nonliving matter that originates from plants).Furthermore,the dry phase of temporary pools usually supports a community of specialized herbaceous plants that can tolerate springtime flooding but grow rapidly in the moist, organically enriched soil after surface water disappears.These plants contribute to the detrital base every year.Although the food web is based mainly on detritus,the processes of decomposition in temporary pools are somewhat different from those in the detritus- based communities of streams and the shore zones of lakes. Detritus decomposes faster when exposed to air during dry periods and has a higher protein content upon flooding in spring than when submerged continuously in permanent water.The reason for this difference is that the terrestrial fungi causing the decomposition of plant detritus in the absence of surface water flourish where oxygen is not limited.In permanent waters,where detrital materials are covered by water,oxygen is not plentiful and decomposition is brought about by aquatic fungi and bacteria,which do not grow as abundantly as terrestrial fungi.Colonizing terrestrial fungi contribute much of the protein of decomposing plant materials,and in feeding experiments limnephilid caddis fly larvae of temporary pools showed a preference for decaying leaves with higher protein levels. Consequently,rapid development,which is so important to animals in transient waters,would be enhanced by the protein-rich detritus as well as by the higher summer temperatures of small bodies of water.

According to paragraph 3,which of the following environments would provide the best food for limnephilid caddis fly larvae?

AStreams and the shore zones of lakes

BPermanent waters with aquatic fungi and bacteria

CWater containing detritus decomposed by terrestrial fungi

DSmaller bodies of water with low oxygen levels

 

7

These principles have led to some practical applications.An increase in productivity following a dry phase underlies the practice in wetland management of alternately draining and flooding wetlands.Aquatic birds such as ducks feed on larval caddis flies and other aquatic invertebrates and also on plants;the increased nutrient levels resulting from exposure of more of the bottom detritus to air and terrestrial fungi enhance productivity throughout the food web.By the seventeenth century,fish farmers in Europe had learned that periodically leaving ponds dry and empty of fish yielded higher productivity in controlled ponds of carp fish than did constant water levels.Through manipulation of water levels,the ponds were wintered as dry basins and periodically over a full year as well-practices that led to increased production of fish.In retrospect then,it appears that after centuries of experimentation to increase productivity in marshes and fish ponds,humans succeeded in duplicating the natural cycle of temporary pools.

The word“periodically”in the passage is closest in meaning to

Aoccasionally

Bcompletely

Cintentionally

Dbriefly

 

8

These principles have led to some practical applications.An increase in productivity following a dry phase underlies the practice in wetland management of alternately draining and flooding wetlands.Aquatic birds such as ducks feed on larval caddis flies and other aquatic invertebrates and also on plants;the increased nutrient levels resulting from exposure of more of the bottom detritus to air and terrestrial fungi enhance productivity throughout the food web.By the seventeenth century,fish farmers in Europe had learned that periodically leaving ponds dry and empty of fish yielded higher productivity in controlled ponds of carp fish than did constant water levels.Through manipulation of water levels,the ponds were wintered as dry basins and periodically over a full year as well-practices that led to increased production of fish.In retrospect then,it appears that after centuries of experimentation to increase productivity in marshes and fish ponds,humans succeeded in duplicating the natural cycle of temporary pools.

According to paragraph 4,why are wetlands alternately drained and flooded in wetland management?

ATo limit the dry phases that interrupt and delay productivity

BTo control the number of harmful insects located in such wetlands

CTo increase the ability of farms to produce large crops of plants

DTo provide more nutrition for the animals in such wetlands

 

9

Look at the four squaresthat indicate where the following sentence could be added to the passage

Alternate draining and flooding has also been used in aquatic farming.

Where would the sentence best fit？Click on a square  sentence to the passage.

10

Temporary pools are freshwater habitats that typically hold water for only part of the year.

AThe larvae of many aquatic insects prefer the more dependable supply of low-level protein provided by terrestrial fungi in temporary pools to the high-level protein provided by aquatic fungi and bacteria.

BBecause of their abundant terrestrial fungi and higher oxygen levels during dry times,temporary pools provide their inhabitants with better nutrition than permanent waters do.

CEvery year,colonizing adults and drought-resistant eggs present during early flooding are more vulnerable to predators than aquatic animals that survive the dry phase of temporary pools.

DSmall aquatic animals in temporary pools face relatively little predation because fish cannot survive dry periods there and fewer predatory insects are adapted to live in such places.

EDecomposition takes longer in temporary pools than in permanent waters but often produces significant amounts of nutritious,high- protein detritus.

FBy observing nature,people have learned the value of alternately draining and flooding areas and have applied this lesson to places where it does not occur naturally.

 

 

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