5. The following data shows the number of water bodies in Bengaluru city from 1973
to 2007. Observe the data and answer the following questions: (4*1 = 4 marks)
60
51
50
38
40
30
25
20
17
10
0
1973
1992
2002
2007
Number of water bodies
Source: Indian Institute of Science
a) Explain the trend in the number of water bodies from 1973 to 2007
b) What could be the possible reason behind this trend?
c) Many water bodies in cities like Bengaluru are eutrophied due to algal growth. What
causes alga to grow so rapidly in water bodies?
d) Explain how eutrophication impacts aquatic animals.
Answers
The following data shows the number of water bodies in Bengaluru city from 1973
to 2007. Observe the data and answer the following questions: (4*1 = 4 marks)
60
51
50
38
40
30
25
20
17
10
0
1973
1992
2002
2007
Number of water bodies
Source: Indian Institute of Science
a) Explain the trend in the number of water bodies from 1973 to 2007
b) What could be the possible reason behind this trend?
c) Many water bodies in cities like Bengaluru are eutrophied due to algal growth. What
causes alga to grow so rapidly in water bodies?
d) Explain how eutrophication impacts aquatic animals.
Eutrophication leads to changes in the availability of light and certain nutrients to an ecosystem. This causes shifts in the species composition so that only the more tolerant species survive and new competitive species invade and out-compete original inhabitants.