Study On Environmental Tolerance Of Antarctic Krill Based On Water Tank Test

With the declining global fishery resources,more and more countries are increasingly concerned about the Antarctic krill resources,Antarctic krill fishing industry gradually expanded.At the same time,the increasingly visible global climate change,including sea ice retreat,ocean warming,ocean acidification and enhanced UV radiation has a significant impact on the hatching habitat of krill and the feeding of zooplankton.In order to make a sustainable development of Antarctic krill biological resources,as a key species in the South Ocean ecosystem,in the current climate change caused by changes in the marine environment factors,the study of Antarctic krill tolerance to the environment or adapt ability is particularly important for krill habitat and life history.The marine environment in the Southern Ocean is complex,and some scholars had studied the changes of habitat to a large extent affected the abundance and temporal and spatial distribution of krill,but it is difficult to understand its living habits and behaviors so far.Domestic and foreign scholars have rarely research about the environmental behavior of Antarctic krill.As the Antarctic continent is far away,the land-based experiment is difficult to achieve.Therefore,it is feasible to observe and study the environmental factors on the tolerance of Antarctic krill by field tank experiment.In order to actively explore the environmental tolerance of Antarctic krill,to further understand the behavioral ecology of Antarctic krill.This study is based on the project "Antarctic marine biological resources development and utilization" of the Ministry of Agriculture,the author carries out experimental aquarium of Antarctic krill through simulation the natural state of the sea,and then observes and analyzes the behavior of Antarctic krill by adopting two methods of gradual and blast type during February2015 to September 2015,December 2015 to May 2016 in Large scale krill factory trawler “Long Da” to the Antarctic waters.The results show that the environmental factors can be used to observe and analyze the Antarctic krill from three aspects:(1)Antarctic krill on salinity adaptability;(2)Tolerance of seawater acidification on Antarctic krill;(3)Research on individual differences in environmental tolerance of Antarctic krill.The experimental results show that:(1)The behavioral status of Antarctic krill was observed and recorded by the two different salinity experimental groups,and the salinity tolerance of Antarctic krill was analyzed.The results showed that the suitable critical salinity of Antarctic krill was about 26 and the limit critical salinity was about 16 under low salinity environment condition.The suitable critical salinity is about 43,and the limit critical salinity is about 55 under high salinity environment condition.(2)In this study,the behavioral status of Antarctic krill was observed and recorded by two different pH experiments.The results show that the tolerable acidity of Antarctic krill was 7.3 ± 0.1,and the limit resistance of Antarctic krill was 6.7 ± 0.1 under different pH environment condition.(3)In the Antarctic sea water tank test,author observed,compared and analyzed the four behavioral states of six groups of Antarctic krill by the adjustment of temperature,salinity and acidification of sea water under different environmental factors.The results show that L1 group first krill appear discomfort phenomenon at 5 ?,15 ? in the last died,while the L6 group appeared at 7 ? krill discomfort phenomenon,but all died at 14 ?.The experimental results show that in the process of temperature change,the body length of krill is sensitive to the change of temperature,and the tolerance is strong.In general,krill were slow to temperature change and weak tolerance.The analysis on different body length of Antarctic krill in the salinity gradient showed that under salinity 26 environment,all krill group began to appear intermittent lying phenomenon;in salinity 17,L1 group and L2 group the krill appear earlier all died,then in salinity 16,L3 group and L4 group appeared krill all died.L5 group and L6 group had all died of krill under salinity 15 environment condition at last.Along with the salinity gradient in the process,when krill began to appear intermittent decumbence,different krill body length were same tolerance.When krill appeared the phenomenon of death,small individual krill resistance is weak,death comes first,Large krill resistance is strong,the last death.The analysis on different body length of Antarctic krill in the pH gradient showed that when the pH is 7.3,small individual krill appear intermittent lying phenomenon,then when the pH is 7.2,the individual krill group appeared intermittent lying phenomenon;when the pH is 6.9,small individual krill first death phenomenon.Then large individual krill appeared death phenomenon in pH 6.6-6.8.The results showed that the Antarctic waters under the acidification was being affected by the fluctuation of the environment,small individual krill resistance is weak,death comes first,Large krill resistance is strong,the last death.