Preliminary Research On Adaptability To Temperature, Growth And Behavior Of Antarctic Krill Based On Aquarium Experiment

Now the research of Antarctic krill has been a key point and hotpot with many countries valuing the strategic position of Antarctic Ocean and increasing input scientific research. Recently, due to the effects of global climate change and human activities such as commercial fishing of Antarctic krill in great quantities, the abundance of Antarctic krill in the Antarctic Peninsula has significantly reduced. In order to establish proper maintenance and management measures to improve the accuracy of evaluation of the Antarctic krill resource, it is essential to make the research on the basic biology of the Antarctic krill, especially with the global climate change, environmental factors influence on the growth of the Antarctic krill and behavior becomes more important. For the journey faraway and bad conditions, it is hard to study on the basis of Antarctic krill biology in the field. Thus, long-term observation and study of the basic biology of Antarctic krill in laboratory aquarium has gradually become an effective way to solve this problem. Since Baker noted difficulties associated with maintaining live krill in the laboratory, a number of short notes has been published on the shipboard maintenance of krill, their transport to shore-based laboratories, and their subsequent care in laboratory aquarium. Scholars has studied series of behaviors of Antarctic krill, such as schooling, feeding, swimming and avoidance behavior and effect of temperature on the growth, maturation and molting of the Antarctic krill. However, time of our participation in exploitation of Antarctic krill is shorter, experience on the basis research of the Antarctic krill biology is lacking, moreover it is too far from our country to the Antarctic Ocean, land-based laboratory research on the living Antarctic krill is unrealistic, so actively explore how to maintain living Antarctic krill on board in the sea is particularly important.To actively develop the Antarctic krill flume experiments, preliminarily inquiry effect of environment change on growth and behavior of the Antarctic krill, promote the understanding of the Antarctic krill basic biology, this study based on the project of agriculture ministry, " Exploitation and Utilization of Antarctic Organic resources ", carried in the large trawls vessel, named “Kai li”, of Shanghai Kaichuang companies from February to June in 2014, preliminary on three aspects:(1) adaptability to temperature of Antarctic krill;(2) effect of temperature and acidification changes on the growth and molting of Antarctic krill;(3) An experimental aquarium for observing the schooling,feeding and avoidance behavior of Antarctic krill. The results indicate:(1) The fit critical temperature and critical temperature of Antarctic krill is 7℃ and(2) 14℃. In addition, when the temperature changes within 0 ~ 6 ℃, regardless of temperature changes happen suddenly or gradually, Antarctic krill mature individuals can quickly adapt to the changed temperature, which shows that when the temperature is below the critical temperature, Antarctic krill has strong ability to adapt to changes in temperature. When the temperature changes within 7 ~ 14 ℃, the conditions of Antarctic krill will change faster, but tend to stable for a long time, that shows Antarctic krill mature individual have a certain tolerance to a slightly higher temperature changes; When reach above the critical temperature, the Antarctic krill mature individual experiencing discomfort status change dramatically in a short time, the condition of critical temperature is the limit temperature that Antarctic krill can withstand.(3) The growth rate and molt period of Antarctic krill will change with the variation of temperature and p H. By the comparison of each experimental group, it shows that the rise of temperature has effect on the growth and molt of the Antarctic krill, and within an appropriate temperature range the growth rate of the Antarctic krill will increase with temperature, molt period will be shorten; Lower p H can reduce the growth rate of the Antarctic krill, and make molt period longer.(4) In the experiment of observation schooling, feeding and avoidance behavior of Antarctic krill under the laboratory conditions, we found schooling behavior has a relationship with the density of the Antarctic krill and sea water in the tank; Antarctic krill have certain photo-taxis, when light intensity bigger, schooling frequency of Antarctic krill is higher. Sudden changes of light intensity can cause the schooling reaction of Antarctic krill. By using real predators and different size, color simulation of predators to threat the Antarctic krill, we found: Antarctic krill escape behavior associated with the size and color of predators. In the tank, the distance between individuals in the school is 5 ~ 10 cm, about 1-2 times the body length; when put a block of sea ice in the tank, we can see krill assemble under the ice which is consistent with the phenomenon of field observations, indicating that Antarctic krill have tendency to sea ice. In addition, when the food is rich in water, feeding individual swims slower; when food is deficient, feeding individual will filter more water for food by swimming faster.