Primary Study On Growth,Behavior And Circadian Rhythm Of Abalone Under Different Light Conditions

Abalone is one of the most important economic shellfish in China.It usually remain under refuges,and light effect growth,behavior and physiology of abalone.Previous studies indicate that darkness condition can promote growth rate and survival rate of abalone in different development stage.Because of different ecological niche of abalone species,their reaction to the changes of light is distinct.So it is significant to study circadian rhythms of abalone,as well as growth,behavior,physiology and photoresponse of abalone under different light condition.And what we research may provide scientific reference for abalone cultivation.1.Effect of constant darkness on growth trait,physiology and behavior of abalone Haliotis discus hannai and HybridNatural light condition and darkness condition were adopted to study growth trait,physiology and behavior of two abalone species(DD:Haliotis discus hannai,H.hannai ?× H.fulgens(?):DF)with two different ages(one year old and two years old).The result indicate that SGR increase of one year old DF which under constant darkness condition is significantly higher than natural light condition.FI of abalone under constant condition is significantly lower compared to natural light condition,but FCR is significantly higher than natural light condition.So lower FI may induce higher FCR under constant darkness condition.The result of behavior research indicate that motion time of abalone under natural light condition is significant more than constant darkness condition.But to feeding time,distance travelled,maximum velocity and mean velocity,there is not significant difference between two light condition.But time span of feeding time and motion time under constant condition is larger than natural light condition.It is the same as the diurnal variation of digestive enzyme and metabolic activities.Digestive enzyme activities are significantly different between natural light condition and constant darkness.a-Amylase activity under natural light condition is significant higher than constant darkness condition,but pepsin activity is significantly lower than darkness condition.So it is speculated that a-amylase activity may induce higher FI under natural light condition and pepsin activity may induce higher FCR under constant darkness condition.Metabolic enzyme activities are also significantly different between natural light and constant darkness.The result indicate that Pyruvate kinase activity under natural light condition is significantly higher than constant darkness condition,specially during daytime(06:00-18:00),so the activity of this period may mainly contribute high activity of Pyruvate kinase.And Lactate Dehydrogenase activity is not significantly different between these two light condition except one year old DD.But to NAD-malate dehydrogenase,there is significant difference between two light condition.The activity under natural condition is higher than constant darkness condition not only during daytime(06:00-18:00),but also nighttime(18:00-00:00).In a word,the energy metabolism level under natural light condition is higher than constant darkness condition.The motion time and energy metabolism level under constant darkness is lower than natural light condition,it is help to improve SGR and FCR of abalone,so darkness is beneficial to the cultivation of abalone.2.Preliminary study of circadian rhythm of abalone Haliotis discus hannaiMacro analysis based on combined cosine method with activity rhythm was adopted to study circadian rhythm of abalone.The result indicate that group abalones as well as individual abalones still perform circadian rhythm under constant darkness.Eyes were remove to research location of circadian center.The result indicate that two eyes removed abalone still perform circadian rhythm under simulation light condition.So it reveal that eyes is not the only organ which sense light to induce circadian rhythm of abalone,there are other photoreception organs to do it in abalone.And the circadian rhythm of two eyes removed abalones become disorder under constant darkness,its circadian period even reach at 33.2h.In addition,the circadian rhythm of only left eye or right eye removed abalone were also study.The result indicate that left eye removed abalone also become disorder.And right eye removed abalone still perform steady circadian rhythm.So the circadian center of abalone main locate on its left eye.3.The reaction of different abalone species to light changesThe big size abalone Haliotis discus hannai(length is about 6 cm,DD)and small size abalone H.discus hannai(length is about 3 cm,DD-3)were adopted to research the reaction of two different abalone sizes to light change.And Haliotis discus hannai(DD),H.fulgens(FF),H.hannai ?×H.fulgens(?)(DF),H.gigantean(GG),H.gigantea?×H.discus hannai(?)(GD)were adopted to study the reaction of different abalone specie.01x,601x,1001x,1401x,1801x,2201x,6001x were set to study reaction of abalone under different light intensity,and 601x,1001x,1801x were set to study reaction of abalone under different light quality.The result show that behavior of DD became significantly different at 1001x,and DD-S became significantly different at 1401x.So the photoresponse ability of DD is higher than DD-S.Behavior of DD became significantly different under different light quality condition at 601x,and DD-S became significantly different at 1801x.So the color recognition ability of DD is higher than DD-S.Behavior of five abalone species all became significantly different compared to darkness condition at 1001x.But the heart rate changes(HRC)of FF became significantly different at 601x;HRC of GG became significantly different at 1401x;HRC of DD became significantly different at 2201x;But two hybrid,the HRC of DF and GD didn't became significantly different,and behavior of GD is more active than DF.So the photoresponse ability of abalone species arrange in order from high to low:FF>SS>DD>SD>DF.The reaction mode to different light quality of GD is similar to DD,their behavior became significantly different under different light quality at 601x;The reaction mode to different light quality of DF is similar to FF,their behavior became significantly different under different light quality at 1001x;But behavior of GG didn't become significantly different at all three light intensity level.And HRC of all five abalone species didn't become significantly different.So color recognition ability of abalone species arrange in order from high to low:DD = SD>FF = DF>SS.In addition,color recognition ability of two hybrids is the same as male parent and distinctly different with female parent.