海南岛近海砗磲(Tridacninae)资源时空变化--以蜈支洲岛为例

TEMPORAL AND SPATIAL VARIATION OF GIANT CLAMS(TRIDACNINAE)RESOURCES IN COASTAL WATERS OF HAINAN:A CASE STUDY OF WUZHIZHOU ISLAND

为了解海南近岸砗磲资源动态变化,于蜈支洲岛周边海域选取5个代表性站位,自2017-2020年采用断面调查的方法,开展了砗磲资源评估、种群数量变化以及其环境相关性分析等,结果显示:(1)各站位砗磲密度为0-30.00×10^(-2) ind./m^(2),且主要分布于3 m水深,在该水深区域,站位3和站位11砗磲密度最高,站位4次之,站位9和站位13最低,统计学分析表明砗磲密度与站位呈显著相关性(P<0.05)。(2)2017年,蜈支洲岛海域四种规格砗磲(壳长<5 cm、5-10 cm、10-15 cm和≥15 cm)均有分布,2018-2020年,未发现壳长≥15 cm的大规格个体。(3)尽管温度及各水质因子均与砗磲密度相关性不显著(P>0.05),水体硝酸盐NO_(3)^(-)浓度与砗磲密度相关系数最高(0.29)。(4)砗磲主要分布于活珊瑚底质(66.67%),其次为礁石(24.24%),砂石底质最低(9.09%)。(5)砗磲外套膜RGB颜色参数值与周边底质颜色存在相关性,空间上,站位3的砗磲外套膜RGB颜色参数值与周边底质颜色相关性高于站位11;时间上,2020年砗磲外套膜颜色与周边底质B值相关系数R高于2017年(0.899 vs.0.712)。研究首次开展了海南岛近岸海域砗磲资源时空动态变化及影响因素研究,其结果可为砗磲资源保护提供数据支持。

To study the dynamic changes of giant clam in coastal waters of Hainan,a 4-year survey from 2017 to 2020 in five stations was conducted in the Wuzhizhou Island on the resource assessment,population changes,and its environmental correlation analysis of giant clams around the island using field cross-sectional survey method.The results show that the density of giant clams surrounding Wuzhizhou Island was 0-30.00×10^(-2) ind./m^(2),and mainly distributed at 3 m water depth.Significant differences were observed among sites(P<0.05).Four sizes of giant clams(shell length<5 cm,5-10 cm,10-15 cm and≥15 cm)were found in 2017,but the≥15 cm ones were missing in 2018,2019 and 2020 surveys.The correlation coefficient between concentration of nitrate NO_(3)^(-) in seawater and giant clam density was the highest(0.29),no significant differences were observed between giant clam density with temperature and water quality factors.The favorite substrate of giant clams was the bottom of living corals(66.67%),followed by rock(24.24%),and sand(9.09%).There was a significant correlation in RGB color parameter value between giant clam mantle and surrounding substrate,in which the correlation coefficients of RGB values in station 3 were higher than those in station 11 in space,and the correlation coefficient of B value in 2020 was higher than that in 2017(0.899 vs.0.712).The temporal and spatial variation of giant clam resources in the area and its impact factors were studied for the first time,which will contribute to the conservation of giant clam.