长江口及其邻近海域春季无脊椎动物群落时空变化

为了研究长江口及其邻近海域无脊椎动物群落结构和多样性的时空变化特征, 我们于1999-2012年春季在长江口及其邻近海域采用定点底层双拖网调查方式进行无脊椎动物调查。结果表明: (1)1999-2012年长江口水域共记录无脊椎动物41种, 隶属6纲10目23科, 其中甲壳动物种类最多(26种), 其次为软体动物(13种)。不同年份种类数量呈先下降后上升的趋势。(2)优势种主要包括日本枪乌贼(Loligo japonica)、三疣梭子蟹(Portunus trituberculatus)、葛氏长臂虾(Palaemon gravieri)和鹰爪虾(Trachypenaeus curvirostris)等, 其在年间存在剧烈变动, 但日本枪乌贼几乎每年都是优势种。(3)长江口无脊椎动物丰度、种类丰富度和多样性在年间均存在显著差异, 1999年和2001年最高, 2004年后呈先下降后恢复上升的趋势。(4)长江口水域的无脊椎动物在每个航次调查中都存在2-3个群聚类型, 并有不同的指示种类。(5)1999-2012年长江口无脊椎动物群落的时间变化可划分为3个阶段: 1999-2001年多样性程度最高, 2004-2007年下降至最低水平, 2009-2012年多样性显著回升, 但尚未恢复到1999-2001年的水平。与20世纪80年代相比, 蟹类减少导致长江口无脊椎动物生物量整体水平下降, 高营养级生物资源衰退带来了无脊椎动物中低营养级生物种群的迅速发展。

Spatial and temporal variations of invertebrate community in the Yangtze River Estuary and its adjacent waters

In order to study the spatial and temporal variations of invertebrate community structure and diversity in the Yangtze River Estuary and its adjacent waters, we investigated invertebrate populations using fixed double bottom trawling during the springs of 1999-2012. Results show that: (1) there were 41 invertebrate species recorded, belonging to 6 classes, 10 orders, and 23 families. Crustaceans were the most recorded species (26 species), followed by mollusks (13 species). The number of recorded species decreased over the sampling period; (2) dominant invertebrates included Loligo japonica, Portunus trituberculatus, Palaemon gravieri, and Trachypenaeus curvirostris. There was significant inter-annual variation but Loligo japonica was the most dominant species across the sampling period; (3) there was significant inter-annual variation in invertebrate abundance, species richness and diversity in the estuary. Abundance, species richness and diversity peaked in 1999 and 2001, and increased after 2004; (4) there were 2 or 3 species assemblages in the estuary, which had different indicator species; (5) the temporal variation in the invertebrate community can be divided into three distinct periods. 1999-2001 featured high species diversity, 2004-2007 saw a decrease to the lowest species diversity, and by 2009-2012 diversity had recovered but was still below the level of 1999-2001. A decline in crab populations has resulted in the decline of overall invertebrate biomass, while deficiencies at high trophic levels has promoted a diversification of invertebrate diet.