黄、东海春季海水胞外酶活性水平分布特征研究

海水胞外酶活性可以指示有机物的分布特征以及微生物的营养状况。我们测定了2017年3月25日至4月15日黄海和东海44个大面站以及2018年4月28日至29日胶州湾湾口附近海域10个站位表层海水中的8种胞外酶活性并研究了其分布特征。2017年春季黄、东海表层海水中碱性磷酸酶和脂肪酶活性较高，高值区出现在苏北沿岸和南黄海中部，碱性磷酸酶与磷酸盐浓度之间呈正相关。其余6种酶(肽酶、几丁质酶、纤维素酶、α-D-葡萄糖苷酶、β-D-半乳糖苷酶、木糖苷酶)活性高值区出现在长江口以东的外海，东海的β-D-半乳糖苷酶、木糖苷酶平均酶活性显著高于黄海。8种酶活性平均值排列顺序由大到小为:碱性磷酸酶、脂肪酶、肽酶、几丁质酶、α-D-葡萄糖苷酶、β-D-半乳糖苷酶、纤维素酶、木糖苷酶，其中α-D-葡萄糖苷酶和β-D-半乳糖苷酶的活性基本一致。2018年春季胶州湾附近海域海水中碱性磷酸酶、脂肪酶、木糖苷酶活性分布为近岸高于远岸，几丁质酶活性为近岸低于远岸。8种酶活性平均值排列顺序由大到小为:碱性磷酸酶、脂肪酶、肽酶、木糖苷酶、α-D-葡萄糖苷酶、β-D-半乳糖苷酶、几丁质酶、纤维素酶，其中几丁质酶和纤维素酶的活性基本一致。黄海的碱性磷酸酶和脂肪酶平均酶活性均显著高于东海和胶州湾附近海域。糖类水解酶(几丁质酶、纤维素酶、α-D-葡萄糖苷酶、β-D-半乳糖苷酶、木糖苷酶)平均酶活性在黄海最低。本文的结果对于理解中国近海海水有机碳的分布、浮游植物及异养细菌对有机碳的降解具有重要意义。

Horizontal distribution of extracellular enzyme activities in the Yellow Sea and the East China Sea in spring

The extracellular enzyme activity of seawater can indicate the distribution characteristics of organic and the nutritional status of microorganisms. Activities of eight extracellular enzymes, including alkaline phosphatase, lipase, leucine aminopeptidase, chitinase, cellulose, xylosidase, α-D-glucosidase and β-D-galactosidase, were measured in the surface seawaters collected from 44 stations of the Yellow Sea and the East China Sea from March 25 to April 15, 2017 and from 10 stations of the Jiaozhou Bay nearby waters from April 28 to 29, 2018. In the spring of 2017, the high-value areas of alkaline phosphatase and lipase appeared in the northern coast of Jiangsu and the middle of the Yellow Sea, alkaline phosphatase activity and phosphate concentration were positively correlated. High activity areas of the other six enzymes (leucine aminopeptidase, chitinase, cellulose, xylosidase, α-D-glucosidase and β-D-galactosidase) appeared in the open sea outside the east of the Changjiang River Estuary. The average activities of β-D-galactosidase and xylosidase were significantly higher in the East China Sea than in the Yellow Sea. The decreasing order of average enzyme activities of the eight enzymes was as follows: alkaline phosphatase, lipase, leucine aminopeptidase, chitinase, α-D-glucosidase, β-D-galactosidase, cellulose, xylosidase, the values of α-D-glucosidase and β-D-galactosidase are proximate. The activities of alkaline phosphates, lipase and xylosidase in the Jiaozhou Bay nearby waters in spring 2018 decreased from nearshore to far shore. The decreasing order of the average enzyme activity of the eight enzymes was as follows: alkaline phosphatase, lipase, leucine aminopeptidase, xylosidase, α-D-glucosidase, β-D-galactosidase, cellulose, chitinase, the values of cellulose and chitinase are proximate. The alkaline phosphatase and lipase activities in the Yellow Sea were significantly higher than those in the East China Sea and Jiaozhou Bay. The average enzymatic activities of polysaccharide hydrolases (chitinase, cellulose, α-D-glucosidase, β-D-galactosidase and xylosidase) were the lowest in the Yellow Sea compared with those in the East China Sea and Jiaozhou Bay nearby waters. Our results are beneficial to understand the degradation of organic carbon by plankton and heterotrophic bacteria and the distribution of marine organic carbon in the coastal water of China.