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Loading ...can any one tell me how Daphnia Respond to Temperature?
I busy reseaching about Daphnia(Water fleas), how the react on change of water temperature and at which temperature that they can’t respond to the stimule that eventual lead to dead?
thanks for the answers
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Let me begin by relating real world experience. I have collected many millions of zooplanktors in my career. You see very definite seasonal changes. When water starts to warm certain copepods begin to appear. Then as the water heats further, the numbers and species varieties increase. At one point the numbers become so vast zooplanktors change the way light penetrates water. This population peak is different for species, but generally last a couple months. As the water begins to chill, the numbers decline. Once winter has set in, very few zooplankters of any species will be found.
There is a lot of work research in which Daphnia are focus. This is rightly so. Dapnia are a key indicator species. Also, form a major part of the food chain for very young fish.
"In conclusion, as the external temperature of the Daphnia increased, its heart rate increased"
http://mason.gmu.edu/~nqureshi/biology/Daphnia.htm
Biology and life cycle of Daphnia
http://www.fao.org/DOCREP/003/W3732E/w3732e0x.htm
Effect of Temperature on the Heartbeat of Daphnia
http://www.umanitoba.ca/faculties/science/biological_sciences/BIOL1030/Lab2/biolab2_4.html
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Daphnia are cold blooded so they do not thermo regulate. As the temperatures go up, the heart rate increases. Usually, the higher the temperature, the more they proliferate as they are resistant to a wide range of temperatures, however, the temperature CAN be too high for them (40 degrees C). Better explained:
The chemical reactions that occur in the cells of Daphnia are dependent on certain enzymes, or proteins, to help the reactions proceed. As you increased the temperature of the water, the metabolism of the Daphnia increased as well, because chemical reactions occur faster at higher temperatures. This means that the heart rate will speed up in order to provide oxygen to the cells as the metabolism increases. However at 40 degrees Celsius, the enzymes break down, and the chemical reactions can no longer occur, so metabolism stops and the Daphnia dies. In its natural environment, Daphnia does not ever experience temperatures of 40 degrees, so this is unlikely to occur. However, they do experience changes in temperature in their natural environment, and their metabolism does increase or decrease as the temperature changes.
http://www.madsci.org/posts/archives/1999-02/918216625.Gb.r.html
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