基于稳定同位素技术的天津大神堂海域人工鱼礁区食物网结构研究

Study of the Food-Web Structure in the Dashentang Artificial Reef Area in Tianjin Using a Stable Isotope Technique

本研究对2016年6月在天津大神堂3个礁区(2010年建成的鱼礁区;2012年建成的鱼礁区;2014年建成的鱼礁区)和对照区域采集的生物消费者及其食物源样品的碳、氮稳定同位素组成进行了分析,通过Iso Source模型计算不同区域生物的食物网基础,并利用氮稳定同位素数据计算消费者的营养级。结果显示,根据δ13C值可以将其食物源分为浮游植物、悬浮颗粒有机物(POM)和沉积相颗粒有机物(SOM)三类;浮游植物对消费者的碳源贡献率(67.2%~81.5%)最大,是大神堂海域的生物食物网的基础。不同区域同一食物源的δ13C和δ15N值没有显著性差异;礁区内滤食性贝类毛蚶(Arca subcrenata)、菲律宾蛤仔(Ruditapes philippinarum)和长牡蛎(Crassostrea gigas)的δ13C值显著高于对照区,作为潜在碳源的浮游植物对其的贡献率显著增加。消费者的δ15N值则介于7.70‰~14.34‰之间,消费者的营养级介于2.0~3.95级之间。游泳生物食性生物的δ15N和营养级在礁区内有所提高,礁区建成的年份越长,其营养级与对照区域的差别越显著。稳定同位素研究表明,人工鱼礁建设可能导致鱼礁区内滤食性生物的食物来源组成改变,并提高游泳生物食性生物的营养级。

The present study aimed to quantitatively evaluate the ecological effects of artificial reefs from the perspective of the food-web structure and provide reference material for marine ecological restoration and conservation research. A stable isotope technique was applied to analyze consumers and their potential carbon sources. Samples were collected from the reef areas built in 2010, 2012, and 2014 and the control area in Dashentang during June 2016. An IsoSource model was used to construct the food web. Stable isotopes were used to calculate the trophic levels of the consumers. The results showed that food sources can be categorized into three categories based on the δ13C values of phytoplankton, particulate organic matter, and soil organic matter. Phytoplankton represented the largest source of carbon for consumers(67.2%~81.5%). The findings from the IsoSource mix model revealed that phytoplankton were the main contributors to the food web in the studied areas. There were no significant differences in the δ13C or δ15N values of the same food sources from different areas. The δ13C values of suspensionfeeding bivalves, including Arca subcrenata, Ruditapes philippinarum, and Crassostrea gigas, were significantly higher in the reef areas than in the control area. The proportion of phytoplankton in the carbon sources for suspension-feeding bivalves was significantly higher in the reef areas than in the control area. The δ15N values of consumer species ranged from 7.70‰ to 14.34‰, and the trophic levels ranged from 2.0 to 3.95. The δ15N values or trophic levels of piscivorous consumers were higher in the reef areas than in the control area, and the level of significance increased with the duration of the reefs. The findings indicate that artificial reefs might induce an abundance of organisms in reef areas, leading to changes in the composition of the food sources of suspension-feeding bivalves and an increase in the trophic levels of piscivorous consumers.