摘要
【目的】松江鲈(Trachidermus fasciatus)是国家二级保护动物,属于广盐性的洄游性鱼类。研究松江鲈增殖放流前适宜的淡化模式。【方法】采用组织切片技术对急性淡水胁迫、不同淡化速度(每次降低5个盐度,并每12、24、48 h降低1次,记为A、B、C组),以及不同淡化幅度(每24 h降低1次,并每次降低2、3、5个盐度,记为D、E、B组)下松江鲈幼鱼鳃的显微结构变化进行研究。【结果】将处于盐度25的松江鲈幼鱼直接放入淡水中进行急性淡水胁迫,1 h时,鳃组织结构形态正常;12 h时,鳃丝出现表皮轻微脱落;24 h时,血细胞出现吸水胀破现象;3 d时,鳃丝和鳃小片的空泡数量显著增多;7 d时,鳃丝和鳃小片表皮脱落最为严重,鳃小片长度增加而宽度减少、末端弯曲,出现细胞溶解现象,形状不规则,空泡除在鳃小片基部出现外、位置也有所上升,血细胞数量减少,线粒体丰富细胞数量增多。盐度25时,A~C组鳃组织结构无明显变化。盐度降至15时,A组鳃丝结构破损现象较其他两组明显。盐度达淡水时,A组鳃组织结构破损严重,鳃小片长度增加但宽度减少,结构不完整,线粒体丰富细胞数量增多,血细胞数量较盐度15时减少;A组鳃丝和鳃小片结构较B、C组有明显差异,不完整程度更严重,B组和C组之间差异不明显,鳃组织结构破损程度相近。起始盐度25,淡水驯化1 h时,D、E组和B组之间的鳃组织结构差异不明显;12 h时,3组鳃组织中空泡数量增多;24 h时,B组和D组鳃中的空泡数量比E组多;3 d时,B组鳃组织较其他两组脱落区域更多;7 d时,E组线粒体丰富细胞及血细胞数量比B、D组多;B组鳃组织结构的不完整程度比D、E组更严重。【结论】随淡水驯化时间增加,松江鲈通过增加鳃小片长度,控制血细胞、线粒体丰富细胞数量等提高自身渗透能力,减少胁迫对鳃的危害。此外,降低淡化速度和幅度有助于松江鲈更好地适应盐度变化,建议选择每日降低2个盐度的淡化模式,以减轻淡水驯化对松江鲈鳃组织结构的损害。
【Objective】Trachidermus fasciatus is a nation’s second-class protected species,belonging to a migratory fish with eurysalinity.The study aims to explore a suitable desalination pattern for T.fasciatus before the proliferation and release of the fish.【Method】The microstructural changes of the gills of juvenile T.fasciatus under acute freshwater stress,different desalination speeds(the salinity was reduced by 5 concentrations each time,and reduced every 12,24,48 h,recorded as A,B,C groups)and different desalination amplitudes(the salinity was reduced once every 24 h,and 2,3 and 5 salinity concentrations were reduced each time,recorded as D,E and B groups)were investigated by tissue sectioning techniques.【Result】The results showed that,when the juvenile T.fasciatus at salinity of 25 was directly put into freshwater for acute freshwater stress,the morphology of gill tissue structure was normal at 1 h;at 12 h,the gill filaments showed a slight epidermal detachment;at 24 h,the hemocytes appeared to be absorbed and swollen;at 3 d,the number of gill filaments and gill lamellae with vacuoles increased significantly;at 7 d,the gill filaments and gill lamellae showed the most serious epidermal detachment,and the length of gill lamellae was increased while the width was decreased,with bent ends,cytolysis and irregular shape.Vacuoles appeared at the base of the branchial lamella and their positions also increased.The number of blood cells decreased and the number of mitochondria-rich cells increased.At salinity of 25,the gill tissues of group A-C did not change significantly.When salinity was reduced to 15,the structural breakage of gill filaments was more obvious in group A than that in groups B and C;when salinity reached freshwater,the gill tissue structure of group A was severely broken,the length of gill lamellae was increased but the width was reduced,the structure was incomplete,the number of mitochondria-rich cells was increased,and the number of hemocytes was reduced compared with that at salinity of 15;the structures of gill filaments and gill lamellae of group A were significantly different than those of groups B and C,with the degree of incompleteness being more serious,and the difference between groups B and C was not obvious.The differences between groups B and C were not obvious,and the gill tissue structure was broken to a similar extent.When the initial salinity was 25 under freshwater acclimation for 1 h,the differences in gill tissue structure were not obvious among group D,group E and group B;at 12 h,the number of vacuoles in gill tissues of the three groups increased;at 24 h,the number of vacuoles in the gills of group B and group D was more than that of group E;at 3 d,the gill tissues of group B had more detachments compared with the other two groups;at 7 d,the number of mitochondria-rich cells and blood cells was more than that of groups B and D.The degree of incompleteness of gill tissue structure was more serious in group B than that in groups D and E.【Conclusion】With the increase of freshwater acclimation time,T.fasciatus improves its osmotic capacity by increasing the length of gill lamellae and controlling the number of hemocytes and mitochondria-rich cells to reduce the harm of stress on gills.In addition,lowering the desalination rate and amplitude will help T.fasciatus to better adapt to the salinity change,and it is recommended to choose the desalination pattern with the salinity decreasing by 2 per day to reduce the damage of freshwater acclimation on the gill tissues and structures of T.fasciatus.
作者
徐建
胡望娇
冯广朋
季强
郑跃平
XU Jian;HU Wangjiao;FENG Guangpeng;JI Qiang;ZHENG Yueping(East China Sea Fisheries Research institute,Chinese Academy of Fishery Sciences/Shanghai Engineering Research Center of Fisheries Stock Enhancement and Habitat Restoration of the Yangtze Estuary,Shanghai 200090,China;Shanghai Songjiang District Aquatic Technology Promotion Station,Shanghai 201669,China;Shanghai Aquatic Wildlife Conservation and Research Center,Shanghai 202162,China)
出处
《广东农业科学》
CAS
2024年第8期115-124,共10页
Guangdong Agricultural Sciences
基金
国家重点研发计划项目(2020YFD0900805)
农业农村部物种资源保护专项(17210163)
上海市水生生物(濒危珍稀物种)增殖放流效果评估项目(2021)。
关键词
松江鲈
淡水驯化
盐度
鳃
组织结构
淡化速度
淡化幅度
Trachidermus fasciatus
freshwater acclimation
salinity
gill
tissue structure
desalination rate
desalination amplitude
作者简介
徐建(1998—),男,在读硕士生,研究方向为水生动物生理生态学,E-mail:xj905173508@163.com;通信作者:冯广朋(1977—),男,博士,研究员,研究方向为水生生物资源养护与开发利用,E-mail:coolwindfgp@163.com。
