海南岛近岸海域赤潮的时空与生物特征

Specific spatial-temporal and biological features of red tide in coastal waters around Hainan Island

为探究海南岛近岸海域赤潮的时空分布规律及赤潮引发种的生态特征,统计分析了2010-2017年海南岛近岸海域赤潮基础数据。结果表明,海南岛近岸海域赤潮多发于1-3月,呈现南部少北部多的空间特征,海口湾及附近海域是赤潮暴发最为频繁的区域;海南岛近岸海域赤潮的发生频率明显呈上升趋势,且多为甲藻赤潮;夜光藻(Noctiluca scintillans)是引发海南岛近岸海域赤潮的主要赤潮生物,有毒赤潮生物为赤潮异弯藻(Heterosigma akashiwo)和米氏凯伦藻(Karenia mikimotoi)。海南岛近岸海域赤潮大多暴发于降水量少且温度适宜的季节,水动力条件较弱、水体富营养化日益严重是赤潮暴发的重要因素。

This paper is devoted to an analysis of the spatialtemporal dynamics of the red tide and the ecological succession of such tide causative organisms based on the historical statistics of the tides in the coastal areas around Hainan Island during the period from 2010 to 2017.As is well known,in the coastal areas around the island,human activities have ever been intensified and thus aggravated the pollutant discharge to the nearshore waters,hence leading to serious eutrophication and the growth of the harmful algal blooms.The results of the increased pollution have eventually caused 14 red-tide accidents that have ever been recorded in the coastal areas around the island from 2010 to2017,and almost occurred in spring and winter,when the insufficient rainfall and the suitable water temperature.The frequentrise of water temperature has led to the consequent rise of the red tide since 2015,especially the dinoflagellate red tides.Temperature and nutrient levels were crucial to both the red tide formation and the ecological succession of the red tide causative species.The red tides tend to be focused more frequently in the northern areas of the island than in the southern ones near Haikou,for example,7 times of red tide have been recorded in Haikou Bay,where always in the state of serious eutrophication and has become the most frequent red-tide hitting spot.What is worse,red tide organisms in the coastal areas around the island have been phytoplankton,with 9 red tide causative species including 5 dinoflagellate species,2 diatom species,1 species of Chrysophyta,and 1 of Xanthophyta.Apart from it,Noctiluca scintillans has become the most causative species that frequently hit the area.To be exact,5 times of red tide hit the island,followed by 3 times of Phaeocystis globosa,and twice of both Scrippsiella trochoidea and Prorocentrum sigmoides,and bad enough,2 toxic species,neurotoxins producing species Heterosigma akashiwo,and hemolytic and ichthyotoxic substances producing species Karenia mikimotoi,hit Haikou Bay in 2015 and 2017,respectively.All this may suggest that,the red tide outbreak in the coastal areas around Hainan Island is the seasons with less precipitation and suitable temperature,relatively weak hydrodynamic conditions and increasingly serious eutrophication.