浙江近海大型有害水母的监测及其与环境关系初探

Monitoring of Large Jellyfish and Its Relationship with the Environment in the Costal Areas of Zhejiang Province

以2009-2014年对浙江沿岸张网和近海帆张网的监测为依据,初步阐述了浙江近海水域水母的种类、分布及高密度分布区的温盐特征。结果表明：（1）浙江沿岸出现大面积分布的有害水母种类主要是口冠水母和霞水母,口冠水母主要分布在浙江中北部水域,而霞水母在浙江近海从南到北都有分布;（2）口冠水母在张网区出现的时间一般是3~4个月（6-9月）,旺发年份持续出现4~5个月,霞水母一般为2~3个月（5-7月）,其出现的时间早于口冠水母,2010年为近6年水母出现数量最多的一年,2011-2014年水母数量逐年减少,2014年为数量最少的一年;（3）2011年在浙江北部近海水母高密度分布区比2009-2010年偏里偏南,2012-2013年水母分布稍偏南。浙江北部近海水母高密度分布区的夏季水温分布值在25~26℃之间,高密度分布区出现在东海暖水与黄海冷水交汇区锋面偏暖水一侧,当水温下降至23℃以下时,水母在该海域基本消失,高密度分布区的表层盐度为28~31,当盐度大于32时,水母消失。

Based on the data of monitoring findings collected from Set net in the costal areas and sail stow net in the offshore of Zhejiang province during 2009 to 2014, the species composition, quantitative distribution of the large jellyfish and the thermohaline structure in the large jellyfish high density areas were analyzed. The results indicated： First, the most important dominant species were Stomolophus meleagris and Cyanea sp. which distributed widely in the costal areas of Zhejiang province. The former mainly distributed in the northern cen- tral costal areas, while the latter distributed from south to north in the costal areas. Second, the occurrence time of the S. meleagris in the Set net area was about three to four months and there were around four to fivemonths of occurrence in the booming year. By contrast, the occurrence of the Cyanea sp. was three to four months, which was earlier than that of the S. meleagris. Besides, the largest amount of jellyfish in the past six years appeared in 2010, the number of the jellyfish decreased year by year during 2011 to 2014, and the smallest amount was in 2014. Third, The jellyfish high density areas of Zhejiang northern offshore in 2011 was further south and west than in 2009 to 2010. It is slightly further south in 2012 to 2013. The summer water temperature in these high density areas was from 25 ℃ to 26℃, and these areas appeared more in the warm side of the intersection of the warm water from the East Sea and the cold water form the Yellow Sea. When the temperature was lower than 23℃, the jellyfish disappeared and when the salinity was higher than 32, they completely disappeared .