灯光诱集对中小型浮游动物群落的生态学效应

2014年5月21—23日和27日在南沙群岛中部海域开展灯光罩网作业的同时,开展诱集前后中小型浮游动物群落变化的初步实验,研究浮游动物群落对灯光反应的敏感性,灯光对群落产生了较为明显的生态学效应。诱集前后共出现浮游动物178种,隶属16个类群。诱集后种类数增加,种类组成的更替率为41%。各类群中,除枝角类外其余15个类群在诱集前后出现的种类均发生变化;除原生动物在诱集后种类数下降外,其他类群的种类数均呈增加的趋势。浮游动物绝大部分类群对灯光诱集较为敏感,趋光性有正有负。诱集前后浮游动物优势种组成发生一定的变化,更替率为50%。诱集前优势种以桡足类为主,而诱集后有尾类的优势地位明显增强。诱集后浮游动物优势种优势度和出现频率均呈明显降低的趋势。南沙群岛海域中小型浮游动物优势种诱集前后均呈聚集分布,各优势种对灯光反应敏感,不同种类对灯光的适应性有所差异。住囊虫等大部分种类对灯光的适应性较强,诱集后聚集强度明显增加;而驼背大眼水蚤和活泼大眼剑水蚤诱集后聚集强度明显下降。桡足类幼虫和小纺锤水蚤等诱集后,聚集强度明显上升,之后又大幅下降。浮游动物生物量和栖息密度在诱集后总体呈明显的增加趋势,以诱集初期增幅最大,之后数量虽有所降低,但仍高于诱集前。灯光可使浮游动物物种丰富度和多样性水平明显提高,但尚未改变浮游动物的群落结构。浮游动物对人造光反应的种间和类群间差异,是由生物自身的生理特征和不同的摄食策略决定的。诱集后游泳生物摄食强度提高,导致了诱集后期浮游动物数量下降。

Effects of light trap on meso-and micro-zooplankton communities in the waters of Nansha Islands, South China Sea

From May 21 to 23 and on May 27, 2014, during light falling net fishing operations in the central Nansha Islands waters, the samples of meso-and micro-zooplankton were collected and analyzed to investigate their changes before and after the light trap. The results showed that zooplankton were sensitive to artificial light at night; the community of zooplankton was affected by artificial nighttime light. A total of 178 zooplankton species belonging to 16 groups were recorded before and after the traps. The results show that the number of species increased after traps. The succession rate of species compositions was estimated at 41%, except Cladocera, all the 15 groups of zooplankton showed significant changes in species composition. Except for the Protozoa which showed a decline in species number, all groups showed a tendency of increased species number after traps. The results also indicated that most of the zooplankton species are sensitive to light traps, either positive or negative, and the occurring frequency of dominant species decreased obviously after light traps. The dominant species composition was changed after light traps (replacement rate was 50%). Before light traps, the Copepoda was the main dominant species. The dominant degree of Appendiculata was dramatically enhanced after light traps. The dominant species of meso-and micro-zooplankton in Nansha Islands trended towards cumulative distribution. All dominant species were sensitive to artificial light. The adaptation to light was different between species. Most dominant species had high adaptation to light; their aggregation intensity was enhanced after light traps, such as Oikopleuridae. The aggregation intensity of Farranula gibbula and Corycaeus agilis was reduced after light traps. At first, the aggregation intensity of Copepoda larvae and Acartia negligens was enhanced, but then the intensity was significantly reduced. Biomass and density of zooplankton were significantly increased in the overall trend, with the largest increase occurring during the initial trap, then declined, but still remaining higher than before the trap. As increase in nekton feeding intensity led to the fall of zooplankton. Although the species richness and diversity were significantly improved by the light trap, the structure of the zooplankton community did not change. Zooplankton species react to artificial light, and the difference between groups is determined by the biological and physiological characteristics of different feeding strategies. Artificial light pollution is a global environmental issue, the ecological impacts of which are only now beginning to be examined in detail. Current knowledge of these impacts in marine ecosystems is insufficient. Although the light trap increases production, but it is important to pay attention to and strengthen the ecological effects of science, and strictly limit the intensity of light trapping with appropriate restrictions on the development of light trap fisheries.