三亚大东海砂质潮间带小型底栖生物的时空分布及影响因素

于2015年和2016年对三亚大东海砂质潮间带进行了季节性的调查,对小型底栖生物及其所处的沉积环境进行了研究,探讨了小型底栖生物的丰度、生物量和群落的时空变化及其与环境变量的关系。共鉴定小型底栖生物类群11个,优势类群为海洋线虫类与桡足类(二者占总丰度83.13%);小型底栖生物年平均丰度为(595.77±442.72)ind·10cm~(–2),小型底栖生物2015年12月的平均丰度为(768.70±533.22) ind·10cm~(–2), 2016年6月平均丰度为(422.85±236.42) ind·10cm~(–2)。丰度分布呈现明显的季节和潮区差异。相关分析结果表明pH、偏态系数与小型底栖生物的丰度呈极显著的负相关,分选系数、中值粒径与之呈极显著的正相关性。小型底栖生物的丰度随季节变化趋势为冬季夏季。食物丰度、溶氧量升高与沉积物粒径的变化是冬季桡足类丰度的大幅增加的主要原因。TWO-WAY ANOVA与ANOSIM结果显示,潮带对小型底栖生物丰度和群落结构的影响在冬季显著。SIMPER分析结果显示,此差异主要来源为桡足类和线虫类。BIOENV分析结果显示,溶氧量和分选系数的组合最能解释这种差异。这一结果可能是由于高、中潮带的人为干扰与砂滩的清理作用导致。夏季潮带间丰度与群落结构差异不显著,pH、盐度、叶绿素含量是影响其分布的主要原因。研究结果可为砂质滩小型底栖生物的研究提供基础数据,也可为全球气候变化背景下砂质潮间带的保护、开发和利用提供科学依据。     

渤海小型底栖动物生物量的初步研究

主要以线虫、桡足类、双壳类、多毛类和动吻5个类群对渤海小型底栖动物的生物量进行了估算,并对其水平分布进行了研究.结果表明,3个航次平均,渤海小型底栖动物年生物量为(干重)0.404g/(m2·a);1998年9～10月和1999年4～5月2个航次中小型底栖动物生物量的水平分布主要表现为渤海中东部和海峡口站位的生物量明显高于其他站位,但在1999年航次,海峡口靠近海岸的站位生物量下降,位于莱洲湾B1站位生物量明显上升.依据小型底栖动物的年生产力P=9B,估算渤海小型底栖动物的年平均生产力为(干重)3.636g/(m2·a).还对渤海小型底栖动物生物量与世界其他海域的进行了比较,认为渤海小型底栖动物生物量的数值与其他海域生物量的数值接近,但略偏低.就不同学者研究所得的线虫平均个体干重进行了比较研究.     

广西北海金海湾红树林湿地海洋线虫群落研究初探

2019年夏季在广西北海市金海湾红树林湿地,设置7个断面,分别采集红树林和光滩小型底栖动物沉积物样品,进行海洋线虫群落结构的研究。分析结果共鉴定出7个小型底栖动物类群,分别为自由生活海洋线虫、桡足类、多毛类、寡毛类、双壳类、有孔虫以及少许未鉴定类群,其中海洋线虫是优势类群,占总丰度的91.79%。小型底栖动物的丰度介于(6.07±1.23)—(200.25±31.75)ind./10cm2之间,海洋线虫的丰度介于(4.16±1.7)—(195.23±30.80)ind./10cm2之间。各个断面,红树林区小型底栖动物的数量都大于相同断面光滩上的。共鉴定出6个海洋线虫优势属,分别为Terschellingia、 Promonhystera、 Paralongicyatholaimus、 Dorylaimopsis、 Halichoanolaimus和Metachromadora,其中Terschellingia为最优势属,优势度为19.35%,在各个断面广泛分布。文中比较分析了该属出现的3个相近种的尾长、化感器直径和化感器距体前端的距离等形态学特征。     

利用小型底栖动物对沉积物重金属污染的评估

采用Hakanson的生态风险指数法和自由生活海洋线虫与底栖桡足类数量之比(N/C比值)的变动对长江口及其邻近海域沉积环境重金属污染状况进行评估.结果表明,研究海域沉积物受到重金属元素Cr,Cu,Zn和As不同程度的污染,近岸站位受测各污染物均呈现中度污染,离岸站位为轻度污染,其中Zn累积最严重.单个污染物潜在生态危害参数表明,受测污染物对海洋生态系统的潜在生态危害非常轻微,其中As和Cu是最主要的生态风险贡献因子.小型底栖动物群落丰度及分布验证了此结果,对As和Cu累积具有明显的生态响应.N/C比值法对研究海域沉积物重金属的污染评估结果与Hakanson的生态风险指数评估结果基本一致,特别是对Cu和As元素的污染评估.结合生物群落分析,利用小型底栖动物两大类群数量之比(N/C)是一个简易可行的沉积环境监测方法.     

Studies on the community structures of meiofauna and marine nematode at six stations in the Southern Yellow Sea,China

1Introduction As part of a comprehensive investigation of ecosys-tem dynamics in the Yellow Sea and East China Sea,astudy has been made of meiofauna,defined here asmetazoans passing a0.5mm sieve but retained by a0.031mm sieve.Meiofauna is an important energeticgroup in benthic small food web due to their smallsize,high abundance and fast turnover rates.Theproduction of meiofauna is equal to or higher than thatof macrofauna in estuaries,shallow waters and deepseas(Gerlach,1971;Platt and Warw…     

小型底栖动物生物量估算方法回顾与思考

小型底栖动物是海洋生态系统的重要组成部分,其生物量估算的准确性影响着海洋生物资源分析和生态系统动力学的研究.对常用的小型底栖动物生物量估算方法进行了介绍,并指出了我国在使用体积估算法时存在的一些问题.在此基础上,对小型底栖动物生物量估算模型研究提出了几条建议.     

Field experiments on the role of epibenthic predators in determining prey densities in an estuarine mudflat

A series of caging experiments was performed on an estuarine mudflat at three seasons of the year, in which Carcinus maenas L. and Pomatoschistus microps (Kroyer) were either excluded from, or allowed to prey upon, the benthos in order to determine to what extent infaunal abundance and mortality was a result of predation by epibenthic predators.The difficulties of conducting and interpreting the results of such experiments are recognized. The benthic macrofauna of this mudflat is dominated numerically by small annelids and there is evidence that adult C. maenas can cause significant increases in the oligochaete component of this assemblage, probably as a result of disturbance caused by its burrowing activity. Juvenile C. maenas on the other hand significantly reduced the abundance of small annelids, particularly the dominant polychaete Manayunkia aestuarina (Bourne) and could be responsible for year-to-year variations in abundance of this species. The role of fish predators (in this case P. microps) is more problematical but it is suggested that in the densities at which they occur naturally on the mudflat they have little direct effect on the abundance of prey species. There is no evidence that seasonal mortality of small annelids is reduced in the absence of predation and this is taken to indicate that not all mortality is due to epibenthic predation. Certain changes in relative abundance of the component species of the harpacticoid copepod community were discerned but it is suggested that the plasticity of their reproductive potential is such that the effect of predation on the group as a whole is usually masked.     

Balance Between Autotrophic and Heterotrophic Components and Processes in Microbenthic Communities of Sandy Sediments: A Field Study

The microscopic community of a microtidal sandy sediment on the Swedish west coast was studiedin situat two depths (0·5 and 4 m) on four occasions (January, April, August and October). Biomass of microalgae, bacteria, ciliates and meiofauna, as well as primary and bacterial productivity, were quantified. Meiofaunal grazing on algae and bacteria was measured simultaneously by radiolabelling intact sediment cores. Autotrophic biomass dominated the microbial community at both depths and on all sampling occasions, accounting for 47–87% of the microbial biomass. Meiofauna contributed 10–47%, while bacteria and ciliates together made up less than 6%. The microflora was dominated by attached (epipsammic) diatoms, but occasional ‘ blooms ’ of motile species occurred. Vital cells of planktonic diatoms contributed to benthic algal biomass in spring. Primary productivity exceeded bacterial productivity in April and August at both depths, while the balance was reversed in October and January. Meiofauna grazed between 2 and 12% of the algal biomass per day, and between 0·3 and 37% of the bacterial biomass. Almost an order of magnitude more algal (17–138 mg C m⁻²) than bacterial (0·1–33 mg C m⁻²) carbon was grazed daily. At the shallow site, primary productivity always exceeded grazing rates on algae, whereas at the deeper site, grazing exceeded primary productivity in October and January. Bacterial productivity exceeded grazing at both depths on all four occasions. Thus, meiofaunal grazing seasonally controlled microalgal, but not bacterial, biomass. These results suggest that, during summer, only a minor fraction (<10%) of the daily microbenthic primary production appears to enter the ‘ small food web ’ through meiofauna. During spring and autumn, however, a much larger fraction (≈30–60%) of primary production may pass through meiofauna. During winter, meiofaunal grazing is a less important link in the shallow zone, but at sublittoral depths, algal productivity may be limiting, and meiofauna depend on other food sources, such as bacteria and detritus.     

Estimates of autumntime benthic secondary production in Laizhou Bay and adjacent Bohai Sea waters

The whole metazoan community inhabiting Laizhou Bay and adjacent Bohai Sea waters were sampled in late autumn,2006.Secondary production estimates for macrofauna and meiofauna were made separately.Total benthic secondary production was as high as 8.38 ± 4.08 g ash-free dry weight(AFDW) m-2 a-1,which represented the autumn production level.In general,macrofaunal secondary production in Laizhou Bay was much lower than that in adjacent Bohai Sea areas.In contrast,meiofaunal secondary production in Laizhou Bay was higher than that in adjacent Bohai Sea areas.Macrofauna contributed 61% to benthic secondary production(5.09 ± 3.26 g AFDW m-2 a-1),lower than the value in previous studies in Bohai Sea.Sediment granulometric characteristics and bottom-water salinity could explain the substantial variability in the macrofauna biomass and production.Meiofaunal production was an important component of benthic production and exceeded macrofauna production under exceptional conditions,e.g.in Laizhou Bay,where macrofauna was restricted.Chlorophyll pigments(Chl-a) concentrations in sediment explained the general meiofaunal biomass and production distribution here.     

胶州湾大沽河口小型底栖动物分布的季节变动

Sediment samples were collected in the intertidal zone of the Dagu River Estuary, Jiaozhou Bay, China in April,July and October 2010 and February 2011 for examining seasonal dynamics of meiofaunal distribution and their relationship with environmental variables. A total of ten meiofaunal taxa were identified, including free-living marine nematodes, benthic copepods, polychaetes, oligochaetes, bivalves, ostracods, cnidarians, turbellarians,tardigrades and other animals. Free-living marine nematodes were the most dominant group in both abundance and biomass. The abundances of marine nematodes were higher in winter and spring than those in summer and autumn. Most of the meiofauna distributed in the 0–2 cm sediment layer. The abundance of meiofauna in hightidal zone was lower than those in low-tidal and mid-tidal zones. Results of correlation analysis showed that Chlorophyll a was the most important factor to influence the seasonal dynamics of the abundance, biomass of meiofauna and abundances of nematodes and copepods. CLUSTER analysis divided the meiofaunal assemblages into three groups and BIOENV results indicated that salinity, concentration of organic matter, sediment sorting coefficient and sediment median diameter were the main environmental factors influencing the meiofaunal assemblages.