Essay on Temperature Fluctuations in Different Environments !
Environmental temperatures fluctuate both daily and seasonally. The temperature of any one area will vary from sunlight to shade and from daylight to dark. The surface temperature of soil may be 30°C higher in the sunlight than in the shade and upto 17°C higher during the day than during the night.
On the desert this spread may be as high as 40°C. The Thar Desert of South Rajasthan (India) shows a diurnal change of 20—30°C for all seasons differences in latitudes often causes variation in the annual temperature cycles.
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With the increased altitude for every 150 meters, the decrease in temperature of 1°C takes place. Further, different environments such as fresh-water, marine and terrestrial environments, are subjected to varied, responses to fluctuating temperature. Temperature fluctuations are comparatively less in the aquatic environment than in the terrestrial environment.
The increase in depth of aquatic medium often increases the temperature fluctuations. There exists a distinct difference in the response of living organisms of the fresh-water and sea to temperature fluctuations because of the presence of dissolved salts in sea water.
The minimum temperature in the sea is —3°C, while in fresh water pond it never goes below 0°C. The maximum temperature of ocean generally goes upto 36°C, but in shallow paols of fresh-water and tide of pool’s littoral zone, temperature may go higher.
In deeper bodies of water, heating and cooling are restricted to the surface strata. But the deeper layers get a lot of heat as a result of what is usually termed vertical circulation, where in, due to circulatory movement of water, surface waters are brought to the deeper regions, and vice versa.
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Studies on the vertical changes of temperature have led to the hypothetical classification of the freshwater media into three strata. The superficial layer of freshwater is constantly stirred by wind and is called epilimnion (Fig. 11.11).
It is the layer of warmer water and its temperature may raise upto 27 C during summers. The stagnant water of the bottom constitutes the hypolimnion. The hypolimnion has temperature of 5°C only.
In between epilimnion and hypolimnion occurs an intermediate zone called thermocline or metalimnion, which has rapid vertical temperature changes. During winter, the temperature of epilimnion of a fresh-water lake becomes 0°C and the lake becomes ice covered. The process of differentiation of fresh-water habitat into these three strata is called thermal stratification.
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In the terrestrial environment fluctuations in temperature arc varied and marked. The lowest temperature recorded for any land mass is —70°C (Siberia in 1947). Higher temperatures may likewise go often 85°C as in certain deserts at noon. However, the water in hot springs and geysers may approach 100’C, and even higher temperatures occur sporadically in the very special situation presented by volcanic areas. In Rajasthan the highest temperature exceeds 50°C.
The differential responses of land and sea to temperature, bestow upon the terrestrial and aquatic organisms certain special adaptations to withstand the rapid changes of temperature. Because of, narrow range of temperature fluctuations in the aquatic media, the relative stability of the aquatic media has led to the adaptation of aquatic animals to a more or less constant temperature.
But this constancy in temperature of aquatic media has its certain own drawbacks as a slight alteration in temperature often brings about mass killings. For example, torrential insects’ habitually inhabiting waters with temperature range of 2—4°C at altitudes of 1000 -1400 meters are adversely affected by even a slight increase in the temperature of water (Mani, 1968 a).
