莱州湾春季鱼类群落关键种的长期变化

Long-term Changes in Keystone Species in Fish Community in Spring in Laizhou Bay

中文关键词: 莱州湾  鱼类群落  食物网拓扑结构  网络分析法  关键种

英文关键词: Laizhou Bay  Fish community  Food-web topological structure  Network analysis  Keystone species

中文摘要:

      关键种对生态系统结构和功能发挥了重要作用，其变化可以引起群落结构振荡和演替，导致生态系统功能紊乱乃至崩溃，因此，了解生态关键种的长期变化有助于解析整个生态系统演替过程。本研究基于莱州湾1959年、1982年、1993年、2003年和2015年春季(5月)底拖网渔业资源调查数据，构建了莱州湾春季鱼类群落食物网拓扑结构，分析了其关键种的长期变化。1959~2015年莱州湾鱼类食物网包含物种21~46个，摄食关系范围70~296个，食物网拓扑结构密度范围为0.155~0.300，种间关联度0.140~0.182，符合自然条件下群落种间摄食关系。1959~2015年莱州湾鱼类群落关键种如下：1959年为六丝矛尾虾虎鱼(Amblychaeturichthys hexanema)、花鲈(Lateolabrax japonicus)、蓝点马鲛(Scomberomorus niphonius)和黄(Lophius litulon)，1982年为鳀(Engraulis japonicus)、黄和小黄鱼(Larimichthys polyactis)，1993年为带鱼(Trichiurus lepturus)、鳀和蓝点马鲛，2003年为细纹狮子鱼(Liparis tanakae)、鳀和黄，2015年为细纹狮子鱼、大泷六线鱼(Hexagrammos otakii)和六丝矛尾虾虎鱼；关键种由经济价值较高的花鲈、小黄鱼和蓝点马鲛等演变为细纹狮子鱼、鳀和六丝矛尾虾虎鱼等经济价值较低的种类；同时，关键种的栖息环境也由中上层与底层生境(蓝点马鲛、花鲈、鳀等)演变为底层单一生境(细纹狮子鱼、大泷六线鱼和六丝矛尾虾虎鱼)；关键种的这种更替导致食物网拓扑结构向简单化发展，在某种程度上也增加了鱼类群落结构脆弱性。

英文摘要:

      Keystone species play an important role in the structure and function of an ecosystem. Changes in keystone species can cause oscillations in community structure and ecological succession, or even result in the dysfunction and collapse of ecosystems. Therefore, understanding long-term changes in keystone species of an ecosystem provides insights into the processes of ecological succession. We built a food-web topological structure for the fish community in Laizhou Bay for each of five years, based on the spring bottom trawl survey data for Laizhou Bay during 1959, 1982, 1993, 2003, and 2015, and then, conducted network analysis to evaluate long-term changes in keystone fish species from 1959 to 2015. The constructed food webs included 21~46 different fish species and 70~296 prey-predator relationships. The structural density of these food webs ranged from 0.155 to 0.300, and interspecific connectivity ranged between 0.140 and 0.182, which matched the ecology of fish communities under natural conditions. The keystone fish species in Laizhou Bay changed from Amblychaeturichthys hexanema, Lateolabrax japonicus, Scomberomorus niphonius, and Lophius litulon in 1959 to Engraulis japonicus, L. litulon, and Larimichthys polyactis in 1982, and then, to Trichiurus lepturus, E. japonicus, and S. niphonius in 1993. After ten years, Liparis tanakae, E. japonicus, and L. litulon became the new keystone fish species, which were replaced by L. tanakae, Hexagrammos otakii, and A. hexanema in 2015. Conclusively, the keystone fish species in Laizhou Bay gradually changed from economically valuable species (e.g., L. japonicas, L. polyactis, and S. niphonius) to those of less economic value (e.g., A. hexanema and L. tanakae). Meanwhile, the diversity of the keystone fish species reduced from different pelagic or groundfishes (e.g., L. japonicus and S. niphonius) to those inhabiting only the bottom. These changes have simplified the topological structure of food webs in Laizhou Bay, which to some extent, has reduced the functional stability of the fish community.