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Climate in the past
In
Sindh from 9,000 to 4,000 years ago, was warm and wet period which
continue up till 3,800 years ago. Temperature were 2 - 3 °C higher
than 1975, causing more rainfall, in winter. While 2,000 - 500 BC was
cold period with low rainfall. Warm period with more rainfall from 400
to 650 AD and cold period with low rainfall continued 900 AD. From
1550 - 1850 AD it was cold period in Sindh and is known as Little Ice
Age.
Effect of climatic change
When ever climate become warm, the ultraviolet radiation increases,
which decreases the population of phyto-plankton. Which is the source
of food for aquatic animals especially fishes. The population of fresh
water fishes and marine water fishes are reduced (see at the back).
Sea
anemone, sea urchin, sea horse, lobster, crab, sea cucumber and
molluscs also reduce simultaneously.
Due to more ultraviolet radiation the sea-weeds
photosynthesis reduced, as a results in the sea-weeds level of Iodine
and potassium sulphate reduces. This means the food of aquatic fauna
become deficient in Iodine and potassium sulphate. |
