Effects Of Important Environmental Factors On The Movement Behavior Of Stichopus Herrmanni

Stichopus herrmanni is a representative sea cucumber around the tropical coral reef sea of southern China.The technology of artificial breeding and seedling culture has been successfully popularized in Hainan Island,which has a broad prospect of development and application.Now,the bottom enhancement of S.herrmanni around Wuzhizhou Island sea area,Sanya,is on process.During the process of sea cucumber sowing and breeding,there would be some problems such as unsuitable seedling placement,missing of sea cucumber after placement or low recapture rate.The behavioral ecology of sea cucumber may contribute to solve these circumstances.Therefore,it is of great significance to find out the influence of environmental factors on the movement behavior of S.herrmanni for the cultivation on the ocean floor and large-scale cultivation of S.herrmanni.In this paper,from the perspective of behavioral ecology,based on the indoor laboratory behavioral research platform,infrared camera technology and behavioral analysis software are used to quantitatively study the behavioral characteristics of S.herrmanni under the influence of different temperature,flow rate and light cycle.The main research contents and results are as follows:1.The influence of temperature on movement behavior of S.herrmanniThe movement state of S.herrmanni under 22 ℃ 、 25 ℃ 、 28 ℃ and 31 ℃ temperature conditions and the circadian rhythm changes of its movement and feeding were studied.The results showed that the movement of S.herrmanni was significantly affected by temperature.The most active state of movement was observed at 31 ℃.Under different temperature gradients,the total movement distance of S.herrmanni at night was significantly greater than that during the day(P < 0.05).The peak of the movement of S.herrmanni appears in the evening and the low in the daytime.The highest distance of movement was between 00:00-02:00 at 31 ℃,which was70.5±20.38 cm,and the lowest distance was between 12:00-14:00 at 25 ℃,which was0.5±0.68 cm.At 18:00,there was a turning point.After that,the feeding ratio of S.herrmanni increased obviously at different temperatures.The highest feeding peak appeared in the evening,and the lowest in the daytime except 22 ℃.The highest feeding peak was at 00:00-02:00 at 31 ℃,and the lowest was at 08:00-10:00 at25 ℃.2.The influence of velocity on the motion behavior of S.herrmanniThe movement state and tendency of the sea cucumber under 0cm/s、4.7±1.2cm/s、10.5±1.7cm/s and 20.8±3.4cm/s water velocity conditions were studied.The results show that the movement state of the sea cucumber is significantly affected by the flow rate.The sea cucumber has the strongest movement ability in still water and the maximum average movement speed as well as the shortest accumulated residence time.With the increase of flow velocity,the movement ability of sea cucumber gradually weakened.But in the range of 0-10.5 ± 1.7cm/s flow velocity,the average movement speed of sea cucumber kept a relatively stable state.The average movement speed range was 3.86-4.75cm/min.When the flow velocity reached 20.8 ±3.4cm/s,the average movement speed of sea cucumber decreased to only0.65±0.61cm/min.In different velocity conditions,S.herrmanni showed the tendency of downstream movement.At high velocity of 20.8 ± 3.4cm/s,the tendency of downstream movement was the most obvious.3.The influence of light cycle on the motion behavior of S.herrmanniThe movement state and tendency of the sea cucumber under full light(24L:0D)、half light(12L:12D)and full dark(0L:24D)light cycle conditions were studied.The results showed that the motion state of S.herrmanni was significantly affected by the light cycle,and the motion distance and feeding ratio of S.herrmanni under half light and full dark conditions were significantly greater than that under full light conditions.S.herrmanni showed the weakest motor ability and the lowest feeding ratio under full light.Under the conditions of full light and full dark,S.herrmanni did not show the characteristics of sleeping,sleeping and nocturnal behavior in the natural state,so it can be seen that exogenous environmental factors are the key factors to determine the behavior rhythm of S.herrmanni.