基于幼体生境的北部湾中国鲎高种群密度形成机制研究

鲎自4.45亿年前出现在地球上，现今只剩4种，分布于北美东部和亚洲东及东南部狭窄海域，是典型的活化石动物。中国鲎是现今地球上个体和经济价值最大的鲎，现已为濒危动物，在北部湾具有世界最高的种群密度。为什么北部湾具有世界上最高的中国鲎种群密度？是温度造成的？还是北部湾大面积滨海湿地（如红树林、海草场等）造就？是人们迫切想知道的。种群密度主要由死亡率和出生率共同决定。中国鲎产卵量大、孵化率高，幼体补充快速，在产卵成体鲎数量相差不大的情况下，种群密度的大小，主要由幼体存活率决定。本项目在走访调查，收集本底资料的基础上，找出现今仍有相当高中国鲎（幼体）种群密度的海域和相对应的低种群密度海域，然后通过对高密度海域和低密度海域的生境的比较研究，及生境因子对幼体存活和生长发育影响的实验室研究，找出中国鲎幼体生长发育的最适生境，再结合北部湾独有的生境特点，阐明北部湾中国鲎高种群密度形成机制。

Horseshoe crabs, which is considered as a kind of typical living fossil of animals, appeared on the earth 445 million years ago, but there only exist four species in narrow sea area of eastern North America and East and Southeast Asia at present. Tachypleus tridentatus, now listed as endangered animals, is one of the largest horseshoe crabs with high economic value on earth and has the highest population density of the world in the Beibu Gulf. Why Tachypleus tridentatus enjoys the highest population density in the Beibu Gulf? Is it because the tempreture or the large-scale coastal wetland (such as mangroves and seagrass field)? People want to find the answer urgently. Population density is mainly determined by mortality rates and birth rates.Tachypleus tridentatus has high egg laying amount, strong hatchability, so its larvals can add quickly, therefore there is no big difference in terms of birthrate between Tachypleus tridentatus living in various sea areas. Consequantly,the population density is chiefly determined by its larval survival rates. On the basis of investigation and collecting data, researchers of this project identify the sea areas with high population density of Tachypleus tridentatus (larvae) and the low ones. Next, through the comparative study of the conditions of habitat between the high and low density sea areas and the laboratory research of effects of habitat factors on the survival and growth of larvae, they find out the most suitable habitat for the development of Tachypleus tridentatus larvae, and then coupled with the unique habitat characteristics of the Beibu Gulf, expound the formation mechanism of the high population density of Tachypleus tridentatus in the Beibu Gulf.