CO_2驱动海洋酸化对三疣梭子蟹(Portunus trituberculatus)幼蟹甲壳结构和组成成分的影响

OCEAN ACIDIFICATION AFFECTS CARAPACE OF CRAB PORTUNUS TRITUBERCULATUS:AN EXPERIMENT

大气中过量的CO_2溶解到海水中造成海洋酸化,破坏了海水原有的酸碱平衡和碳酸盐溶解平衡。甲壳类动物甲壳的形成过程依赖于海水正常的酸碱平衡和碳酸钙溶解平衡。本研究以三疣梭子蟹幼蟹为研究对象,采用CO_2与空气的混合气体对自然海水进行曝气,模拟在现有CO_2排放速度下,本世纪末和下世纪末海洋酸化的程度(表层海水p CO_2分别为750μatm,1500μatm),研究不同海洋酸化程度对三疣梭子蟹幼蟹甲壳结构和组成成分的影响。结果发现,海洋酸化导致:(1)三疣梭子蟹幼蟹甲壳上表皮的外表面微刺排列趋于简单化,由2—3个微刺为主要排列形式逐渐变为单个微刺排列的形式;(2)甲壳厚度变薄,甲壳厚度从正常海水对照组(pH 8.13±0.02)90.20±4.85μm,变薄到OA1组(pH 7.98±0.02)84.53±13.71μm,再到OA2组(pH 7.75±0.03)61.94±13.43μm,并且有随海洋酸化程度加重厚度变得更薄的趋势;(3)随着酸化程度的加深,甲壳中甲壳素含量显著上升,从对照组(13.10±0.07)%上升到OA1组(14.22±0.04)%,再到OA2组(14.30±0.06)%(P=0.000**);(4)甲壳中钙、镁元素含量及钙镁比没有明显变化。结果表明海洋酸化对三疣梭子蟹幼蟹甲壳的结构和甲壳素含量产生了较大影响。

Excess CO2 in the atmosphere causes ocean acidification（OA）,under which the formation of crustacean carapace would be affected.We conducted an experimental study with mixed gas of CO2 and natural air to simulate the OA at sea surface in the ends of 21 st and 22 nd centuries in p CO2 at 750（OA1） and 1500μatm（OA2）,respectively,on carapace structure of juvenile swimming crab Portunus trituberculatus,against the control,the modern seawater value of 483μatm.Results show that OA affected：（a） The arrangement of spinules on the epicuticle of the external surface.The carapace became simpler from 2—3-spinule pattern to a single one.（b） The carapace thickness of OA condition was reduced 90.20±4.85μm for the control,84.53±13.71μm for OA1,and 61.94±13.43μm for OA2,and would be thinner as OA intensified.（c） The chitin content of OA groups increased significantly：（13.10±0.07）% for the control,（14.22±0.04）% for OA1,and（14.30±0.06）% for OA2.（d） The contents of calcium and magnesium in carapace in OA groups increased,but did not show significant difference,and Ca/Mg ratio remained unchanged.Therefore,OA did have some effects on the structure and the chitin content of juvenile swimming crab carapace.