红沿河海域常见水母的食物组成分析——基于稳定同位素和脂肪酸标记法

为了探究不同种类水母对浮游食物网的摄食影响,采用碳氮稳定同位素和脂肪酸标记法,研究分析了渤海红沿河海域常见的4种小型水母(伞径直径5 cm:卡玛拉水母Malagazzia carolinae、球形侧腕水母Pleurobrachia globosa、帽铃水母Tiaricodon coeruleus、半球美螅水母Clytia hemisphaerica和3种大型水母(伞径10—200cm:沙海蜇Nemopilema nomurai、海月水母Aurelia aurita)和白色霞水母Cyanea nozakii)的食物组成。结果表明,不同种类水母的食物组成存在差异。其中卡玛拉水母、球形侧腕水母、帽铃水母、半球美螅水母和白色霞水母均偏肉食食性,食物组成中动物性食物所占比例更高,高于海月水母与沙海蜇。在食物粒径谱上,帽铃水母和半球美螅水母较大粒径的食物比例均高于小粒径的悬浮有机物(POM)比例。卡玛拉水母和球形侧腕水母各个粒径食物比例接近。大型水母中,白色霞水母的食物中大粒径的浮游动物的比例高于海月水母,更高于沙海蜇。由此看来,小型水母和大型的白色霞水母的暴发会直接影响大中型浮游动物数量,海月水母的暴发对不同大小的浮游生物均会产生一定的影响。而沙海蜇的暴发会大量摄食1 mm的小型浮游生物和POM,对大中型浮游动物以及更高营养层生物(鱼类等)的影响可能是通过蜇伤以及饵料竞争导致的。因此,不同种类水母暴发对浮游生物的影响存在差异。本研究从摄食角度初步探究了水母对海洋生态系统物质循环和能量流动的影响,为水母暴发的灾害防治提供了数据支持。

FOOD COMPOSITION OF COMMON JELLYFISH SPECIES IN HONGYANHE AREA REVEALED BY FATTY ACID BIOMARKERS AND STABLE CARBON AND NITROGEN ISOTOPES

To explore the feeding effects of different jellyfish species on plankton food webs, the food composition of 4 species of small-sized jellyfish (umbrella diameter:<5 cm:Malagazzia carolinae, Pleurobrachia globosa, Tiaricodon coeruleus, Clytia hemisphaerica) and 3 species of large-sized jellyfish (10-200 cm:Nemopilema nomurai, Aurelia aurita and Cyanea nozakii) commonly seen in the Hongyanhe coastal area of the Bohai Sea, Liaoning, China were analyzed using stable carbon and nitrogen isotopes and fatty acid biomarkers. Results show that the food compositions of different jellyfish species were different. M. carolinae, P. globosa, T. coeruleus, C. hemisphaerica, and C. nozakii were mostly carnivorous, and the proportion of animal food in food composition was higher than A. aurita and N. nomurai. In the food particle size spectrum, T. coeruleus and C. hemisphaerica had higher proportion of finer suspended organic matter (POM). M. carolinae and P. globosa had similar proportions of food in different particle sizes. Among the large-sized jellyfish, C. nozakii had a higher proportion of large-sized zooplankton than A. aurita and N. nomurai. Therefore, the blooms of small-sized jellyfish and large-sized C. nozakii could directly affect the biomass of large- and medium-sized zooplankton, and the bloom of A. aurita would have a certain impact on plankton of different sizes. However, the bloom of N. nomurai would consume a large number of fine-grained (<1 mm) plankton and POM. The impact on large- and medium-sized zooplankton and higher trophic organisms (such as fish) might be caused by stinging and food competition. Therefore, the impact of different species of jellyfish bloom on plankton was different. By studying the effects of jellyfish on the material cycle and energy flow of marine ecosystem from the perspective of feeding, supportive data to the prevention and control of jellyfish blooms are presented in this paper.