基于GIS的中国近岸海域1950—2020年赤潮时空变异格局

GIS-based temporal and spatial patterns of red tides in the coastal waters of China from 1950 to 2020

基于1950—2020年的赤潮公报等数据,采用GIS方法分析了中国近岸海域赤潮的时空分布规律与赤潮优势种演变.结果表明,过去70年中国近岸海域赤潮事件共发生1701次,累计赤潮面积超过25万km^(2),整体呈先增后减的趋势.赤潮高发期主要在4—8月,其中5月赤潮发生次数最多,累计面积最大.赤潮发生月份由南到北呈季节性变化趋势,南部海域赤潮发生月份要早于北方.赤潮事件主要以180 km^(2)以内的小面积赤潮为主,大部分在11 d以内.赤潮高发区集中在河口、海湾、港湾及污染排放量较大的海域.诱发赤潮次数较多的赤潮优势种包括夜光藻、中肋骨条藻、东海原甲藻和米氏凯伦藻等.其中,夜光藻、中肋骨条藻和米氏凯伦藻在中国近岸海域均有分布,而东海原甲藻均发生在东海海域.夜光藻和中肋骨条藻一年四季均具备生长条件,米氏凯伦藻和东海原甲藻则在5—6月最为频繁.海水水质状况分析表明,中国近岸海域赤潮发生次数与海水水质污染程度密切相关;赤潮优势种的发生月份也与温度和盐度相关,赤潮优势种的季节性生长和空间分布可直接影响中国近岸海域的赤潮发生规模.

Based on the red tide bulletin and other data from 1950 to 2020,the temporal and spatial distribution of red tide and the evolution of dominant species of tide organisms in the coastal waters of China were analyzed using the Geographic Information System(GIS)method.The results show that there have been 1701 red tide events in the coastal waters of China in the past 70 years,and the accumulated red tide area has exceeded 250000 km^(2),showing a trend of first increasing but then decreasing.The high incidence periods of red tide are mainly from April to August,in which May has the largest number of red tides and the largest cumulative area.The red tides show a seasonal trend from south to north,and they occur earlier in the south than that in the north.The red tide events are mainly occured within 180 km^(2),lasting from one to ninty-nine days,most of which are within 11 days.The high frequency areas of red tides are concentrated in estuaries,bays,harbors and sea areas with large pollution emissions.The dominant species that induce more red tide events include Noctiluca scintillans,Skeletonema costatum,Prorocentrum donghaiense and Karenia mikimotoi.Among them,Noctiluca scintillans,Skeletonema costatum and Karenia mikimotoi are distributed in all the coastal waters of China,while Prorocentrum donghaiense occurs in the East China Sea.Noctiluca scintillans and Skeletonema costatum are able to grow in all seasons of the year,while Karenia mikimotoi and Prorocentrum donghaiense grow most frequently in May and June.The sea water quality analysis in different sea areas shows that the number of red tides in the coastal waters of China is closely related to the degree of sea water pollution.The months in which the dominant species of red tides occur are also related to temperature and salinity.The seasonal growth and distribution pattern of the dominant species of red tides can directly affect the spatiotemporal scale of red tides in the coastal waters of China.