| in order to explore the ecological status and energy transfer efficiency of zooplankton in the marine food web,this study analyzed the community composition of zooplankton in the Muping marine ranch in 2017,and further compared the shallow water type ? and type ? plankton nets for various the effectiveness of zooplankton capture,to determine the appropriate collection network type for each zooplankton.In addition,due to the small size of copepods and fast feeding speed,it was difficult to directly observe their feeding behavior and analyze their feeding types.In this paper,the high-speed camera method was used to study two dominant copepod species in natural environment,Calanus sinicus and Centropages dorsispinatus,and preliminarily discussed the feeding selectivity of the two species with different size range of baits The results can provide a more accurate basis for calculating the energy flow efficiency and carbon sink pattern of copepods in the food web.Main results were as follows:1.49 species of zooplankton were identified from March to November 2017 in the Muping marine ranch,of which zooplankton suitable for shallow water type ? net high-efficient collection included large copepods such as Calanus sinicus,Labidocera euchaeta,and small jellyfish,Sagitta,etc.;And suitable for shallow water type ? net high-efficient collection included small copepods such as Paracalanus parvus,Oithona similis,Centropages abdominalis,Centropages dorsispinatus,Oikopleura dioica,Cladocera(Penilia avirostris,Evadne tergestina)and planktonic larvae.The abundance of Mysidacea and some Planktonic larvae(such as Alima larvae,Brachyura zoea,Brachyura megalopa)in shallow water type ? and type ? nets were all in within the same order of magnitude,both network types were applicable2.The seasonal variation of zooplankton abundance in the Muping marine ranch was mainly manifested as the highest in summer,autumn came next and the lowest in spring.The spatial distribution of the total abundance of zooplankton was mainly concentrated in the central and western seas,while the high total abundance area in August was only located in the eastern coastal waters3.The dominant species of zooplankton in the Muping marine ranch included 16 species.Calanus sinicus,Labidocera euchaeta were common dominant species in the shallow water type ? net.Paracalanus parvus,Oithona similis were the predominant species of shallow water type ? nets throughout the year.Calanus sinicus,Mvsidacea,Brachyura zoea and Penilia avirostris were the predominant species peculiar to the shallow water type ? plankton net.Corycaeus affinis was the exclusive dominant species of shallow water type ? net.4.The diversity index of shallow water type ? network from May to September was higher than that of ? network.Whether it was shallow water type ? network or ?network,the trend of uniformity was similar with the diversity index5.The feeding modes of Calanus sinicus and Centropages dorsispinatus were of the feeding-current type,which is mainly manifested as intermittent sinking and repeated movement after constantly swinging the appendages.In the process of feeding,the appendage(mainly the second antenna,the big jaws,etc.)was constantly swinging to generate feeding water,and the baits were carried to the area that can be detected by itself.6.The swing frequency of the appendage of Calanus sinicus was above 250 ?m>100-250 ?m>10-20 um>50-100 ?m>0.7-10 ?m>20-50 ?m.Based on this,we speculated that Calanus sinicus preferred the bait with the size range of above 250 ?m most,and then preferred the bait size of 100-250 ?m and 10-20 ?m,but the swing frequency difference of two size ranges was not significant.At the same time,the results of feeding duration of the three feed grains showed that the feeding duration of 100-250?m and 10-20 ?m was the longest,with no significant difference,and the feeding duration of 250 ?m was shorter than that of the first two.It was speculated that the feeding time was related to the feed composition.Below 250 ?m,phytoplankton feed was mainly used,and the feeding time was long;above 250 ?m,protozoan feed was mainly used,and the energy was relatively sufficient.The results further showed that the bait of>250 ?m was the type most inclined to feed,and the second type was 100-250 ?m and 10-20 ?m.7.Centropages dorsispinatus appendages oscillation frequency from high to low was 100-250 ?m,50-100 ?m,20-50 ?m 10-20 ?m,250 ?m above,0.7-10 ?m,in addition,the fluctuation frequencies of appendages in the first three particle size ranges were not significantly different,so it was speculated that 20-250 ?m was the particle size range that the appendages tended to feed on.At the same time,the results of the continuous feeding duration of Centropages dorsispinatus indicated that the feeding duration of Centropages dorsispinatus for the three particle size ranges between 20 ?m and 250?m were not significantly different,which further indicated the feeding tendency of Centropages dorsispinatus for the 20-250 ?m bait.8.By comparing the feeding micro-behaviors of the two copepods in the same bait size range,we found that in the bait size range of 10-250 ?m,the appendage swing frequency of Centropages dorsispinatus was significantly higher than that of Calanus sinicus(P<0.05),while the continuous feeding time was shorter than that of Calanus sinicus(P<0.05).It is speculated that Calanus sinicus and Centropages dorsispinatus had different feeding niches.Calanus sinicus preferred a size of more than 250 ?m bait,and its appendage had a low swinging frequency and a long feeding time in the range of 10-250 ?m bait,while Centropages dorsispinatus was the opposite9.By comparing the feeding micro-behaviors of the two copepods,it was found that there was no significant difference in the frequency and duration of Calanus sinicus appendage swing between the female body and the male body under the same particle size,while there was a significant difference in the frequency and duration of Centropages dorsispinatus appendage swing between the female body and the male body under the same particle size. |
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