台风“梅花”对潮滩大型底栖动物群落的影响研究

Study on the influence of Typhoon“Muifa”on the macrobenthic community of tidal flat

台风会对潮滩生态系统造成严重影响,特别是对大型底栖动物群落组成及分布影响显著。台风期间现场资料匮乏,导致人们对台风如何影响生态系统的认识仍十分有限。为此,本研究选取长江口崇明东滩盐沼-光滩断面于2022年9月台风“梅花”前、中、后进行水动力观测和大型底栖动物同步采样。研究发现:(1)台风“梅花”期间,盐沼中有效波高是正常天气下的2~4倍,浪流联合剪切应力是正常天气下的10倍;(2)台风“梅花”过后1周内,盐沼中底栖动物的物种数、丰度、生物量分别是台风前的1.9倍、3.8倍、3.0倍,优势种种类(谭氏泥蟹(Ilyoplax deschampsi)、拟沼螺(Assiminea sp.)、堇拟沼螺(Assiminea violacea)、河蚬(Corbicula fluminea))比台风过境前(拟沼螺、谭氏泥蟹、河蚬)增加了一种(堇拟沼螺),第一优势种由拟沼螺变为谭氏泥蟹;(3)台风“梅花”过后1周内,盐沼中大型底栖动物的物种数、丰度和生物量均增加,而盐沼前缘光滩上大型底栖动物的丰度降低,原因是盐沼前缘光滩上的底栖动物(谭氏泥蟹、拟沼螺、河蚬)在台风导致的强水动力胁迫下,迅速迁移至水动力相对弱的盐沼中;(4)台风“梅花”过后2周,盐沼中大型底栖动物的丰度恢复。本研究结果表明盐沼植被不仅具有消浪缓流、保滩护岸等生态服务功能,还可在台风期间为底栖动物提供避难所。

Typhoons can have serious impacts on tidal flat ecosystems,particularly on the composition and distribution of macrobenthic communities.However,there is a lack of field data during typhoons,and the understanding of how typhoons affect the ecosystem is still limited.Therefore,this study conducted hydrodynamic observations and synchronous sampling of macrobenthic organisms before,during,and after Typhoon“Muifa”in September 2022,along the salt marsh-mudflat transect in the Chongming Dongtan area of the Changjiang River estuary.The study found:(1)During Typhoon“Muifa”,the effective wave height in the salt marshes was 2−4 times that of normal weather,and the combined wave-current shear stress was 10 times higher.(2)Within a week after Typhoon“Muifa”,the species number,abundance,and biomass of macrobenthic organisms in the salt marshes were 1.9,3.8,and 3.0 times higher than before the typhoon,respectively.The dominant species of the salt marsh(Ilyoplax deschampsi,Assiminea sp.,Assiminea violacea,Corbicula fluminea)increased by one(Assiminea violacea)compared with that before the typhoon(Assiminea sp.,Ilyoplax deschampsi,Corbicula fluminea),and the primary dominant species shifting from Assiminea sp.to Ilyoplax deschampsi.(3)Within a week after Typhoon“Muifa”,the indicators of species number,abundance,and biomass of macrobenthos in the salt marsh increased,while the abundance of macrobenthic organisms on the mudflats at the forefront of the salt marsh decreased.This is attributed to the macrobenthic organisms(Ilyoplax deschampsi,Assiminea sp.,Corbicula fluminea)on the mudflats migrating rapidly to the relatively less hydrodynamically stressed salt marshes during the strong hydrodynamic stress caused by the typhoon.(4)Two weeks after Typhoon“Muifa”,the abundance of macrobenthos in salt marshes recovered.The results of this study indicate that salt marsh vegetation not only provides ecological services such as wave attenuation,flow reduction,and shoreline protection,but also serves as a refuge for macrobenthic organisms during typhoons.