The marine polychaete Arenicola marina: its unusual arsenic compound pattern and its uptake of arsenate from seawater.

Arsenic compounds in the marine polychaete Arenicola marina collected from Odense Fjord, Denmark were determined by HPLC-ICPMS. In contrast to most other marine animals, A. marina contained most of its water soluble arsenic as inorganic forms, arsenite (58%) and arsenate (16%), and arsenobetaine was present as a minor constituent (6%) only. Other arsenic compounds detected in A. marina were dimethylarsinate (4%), two arsenosugars (1 and 3%), tetramethylarsonium ion (1.5%), and arsenocholine (<1%). A new arsenobetaine -trimethylarsoniopropionate-previously only reported in fish, was also present at trace levels (<1%), and an unknown anionic arsenical (approximately 10%) remains unidentified. When A. marina was exposed in laboratory experiments to different concentrations of arsenate in seawater (10, 50. 100, 500 and 1000 microg As 1(-1)) the polychaetes accumulated arsenic in a dose dependent. non-linear manner. Most of the accumulated arsenic was biotransformed to arsenite and dimethylarsinate. with the remainder being accumulated as unchanged arsenate. None of the other arsenic compounds naturally present in A. marina increased in concentration following arsenate exposure.     

Effects of mud sedimentation on lugworm ecosystem engineering

Benthic ecosystem engineering organisms attenuate hydrodynamic or biogeochemical stress to ameliorate living conditions. Bioturbating infauna, like the lugworm Arenicola marina, determine intertidal process dynamics by maintaining the sediment oxygenated and sandy. Maintaining the permeability of the surrounding sediment enables them to pump water through the interstitial spaces, greatly increasing the oxygen availability. In a field experiment, both lugworm presence and siltation regime were manipulated to investigate to what extent lugworms are able to cope with sedimentation of increasing mud percentage and how this would affect its ecosystem engineering. Fluorescent tracers were added to experimentally deposited mud to visualise bioturbation effects on fine sediment fractions. Lugworm densities were not affected by an increasing mud percentage in experimentally deposited sediment. Negative effects are expected to occur under deposition with significantly higher mud percentages. Surface chlorophyll a content was a function of experimental mud percentage, with no effect of lugworm bioturbation. Surface roughness and sediment permeability clearly increased by lugworm presence, whereas sediment erosion threshold was not significantly affected by lugworms. The general idea that A. marina removes fine sediment fractions from the bed could not be confirmed. Rather, the main ecosystem engineering effect of A. marina is hydraulic destabilisation of the sediment matrix.     

Impact of lugworms (Arenicola marina) on mobilization and transport of fine particles and organic matter in marine sediments

We investigated the impact of sediment reworking fauna and hydrodynamics on mobilization and transport of organic matter and fine particles in marine sediments. Experiments were conducted in an annular flume using lugworms (Arenicola marina) as model organisms. The impact of lugworms on sediment characteristics and particle transport was followed through time in sediments experimentally enriched with fine particles (< 63 μm) and organic matter. Parallel experiments were run at low and high water current velocity (11 and 25 cm s^− 1) to evaluate the importance of sediment erosion at the sediment–water interface. There was no impact of fauna on sediment composition and particle transport at current velocity below the sediment erosion threshold. At current velocity above the erosion threshold, sediment reworking by lugworms resulted in dramatic particle transport (12 kg dry matter m^− 2) to an adjacent particle trap within 56 days. The transported matter was enriched 6–8 times in fine particles and organic matter when compared to the initial sediment. This study suggests that sediment reworking fauna is an important controlling factor for the particle composition of marine sediments. A. marina mediated sediment reworking greatly increases the sediment volume exposed to hydrodynamic forcing at the sediment–water interface, and through sediment resuspension control the content of fine particles and organic matter in the entire reworked sediment layer (> 20 cm depth).     

Chemical diversity of scleractinian corals revealed by untargeted metabolomics and molecular networking

The chemical diversity of scleractinian corals is closely related to their physiological, ecological, and evolutionary status, and can be influenced by both genetic background and environmental variables. To investigate intraspecific variation in the metabolites of these corals, the metabolomes of four species(Pocillopora meandrina,Seriatopora hystrix, Acropora formosa, and Fungia fungites) from the South China Sea were analyzed using untargeted mass spectrometry-based metabolomics. The results ...     

Microbial diversity in Huguangyan Maar Lake of China revealed by high-throughput sequencing

Huguangyan Maar Lake is a typical maar lake in the southeast of China. It is well preserved and not disturbed by anthropogenic activities. In this study, microbial community structures in sediment and water samples from Huguangyan Maar Lake were investigated using a high-throughput sequencing method. We found significant differences between the microbial community compositions of the water and the sediment. The sediment samples contained more diverse Bacteria and Archaea than did the water samples. Actinobacteria, Betaproteobacteria, Cyanobacteria, and Deltaproteobacteria predominated in the water samples while Deltaproteobacteria, Anaerolineae, Nitrospira, and Dehalococcoidia were the major bacterial groups in the sediment. As for Archaea, Woesearchaeota (DHVEG-6), unclassified Archaea, and Deep Sea Euryarchaeotic Group were detected at higher abundances in the water, whereas the Miscellaneous Crenarchaeotic Group, Thermoplasmata, and Methanomicrobia were significantly more abundant in the sediment. Interactions between Bacteria and Archaea were common in both the water column and the sediment. The concentrations of major nutrients (NO^3-, PO4^3-, SiO3^2- and NH4^+) shaped the microbial population structures in the water. At the higher phylogenetic levels including phylum and class, many of the dominant groups were those that were also abundant in other lakes;however, novel microbial populations (unclassified) were often seen at the lower phylogenetic levels. Our study lays a foundation for examining microbial biogeochemical cycling in sequestered lakes or reservoirs.     

Effects of diesel oil on the polychaete Annelida in model benthic ecosystem

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我国不同纬度白骨壤种群遗传多样性和遗传分化的研究

红树林是生长在热带、亚热带潮间带的一种常绿木本植物群落,分布于我国的海南、广西、广东、福建和台湾5省区的沿海地带,它具有胎生、抗盐及富含单宁等特性,这使得它与其他陆生植物群落存在着很大差别.虽然科学家已对红树植物在生理、生态、能量生态和污染生态方面开展了较为详尽的研究工作[1,2],但对其遗传结构研究较少.     

基于mtDNA ND1基因序列研究不同地理群体波纹唇鱼的遗传多样性和遗传分化

以海南陵水、马来西亚、西沙、南沙4个海域共101尾波纹唇鱼(Cheilinus undulatus)作为研究对象,利用线粒体DNA ND1基因序列对波纹唇鱼进行了遗传多样性分析。通过PCR扩增、克隆与序列测定技术,获得ND1基因序列长度为975 bp,其多态性遗传参数统计显示,101个个体存在13个变异位点,14个单倍型,总群体单倍型多样性(Hd)为0.292,平均核苷酸差异数(K)为0.335,核苷酸多样性指数(Pi)为0.000 35,表现出遗传多样性处于较低水平。Tajima′s D中性检验结果为-1.768 09(P=0.031)表明波纹唇鱼在历史上经历过近期群体扩张或瓶颈效应。分子方差分析(AMOVA)表明遗传变异来自群体内。该结果可为今后波纹唇鱼的种质资源保护工作提供必要的科学依据。     

Influence of environmental disturbances and reproductive strategy on genetic diversity and differentiation of Zostera marina populations on the southern coast of Korea

The genetic diversity and differentiation of four Zostera marina populations along the southern coast of Korea were estimated using random amplified polymorphic DNA (RAPD) markers to determine the effects of natural and anthropogenic stresses and reproductive strategy on within‐population genetic diversity. The mean number of alleles and gene diversities, indicating population genetic diversity, was highest in the Z. marina population that was exposed to repeated environmental disturbances, and lowest in the most undisturbed population. The higher genetic diversity in the disturbed population was associated with a higher contribution of sexual reproduction to population persistence. This suggests that both the level of disturbances and the reproductive strategy for population persistence contributed significantly to population genetic diversity at the study sites. According to the analysis of molecular variance (AMOVA), 76% genetic variation was attributable to differences among individuals within populations. The observed genetic differentiation (F_ST = 0.241) among Z. marina populations at the study sites appeared to result from reduced meadow size, increased genetic drift, and a high incidence of asexual reproduction. Increased population genetic diversity can enhance resistance and resilience to environmental disturbances; thus, this investigation of seagrass population genetics provides valuable new insights for the conservation, management, and restoration of seagrass habitats.     

翡翠贻贝3个野生种群遗传多样性分析

采用表型性状、RAPD和ISSR分子标记对取自广西北海、广东湛江和汕尾的3个翡翠贻贝Perna viridis种群进行遗传多样性分析。翡翠贻贝种群间表型性状(壳长、壳高、壳宽、软体部重、体重和肥满度指数)存在显著的差异(p<0.05)。11个RAPD引物共扩增出114条带,扩增片断大小为237—2099 bp,种群的多态性位点比例和遗传多样性指数分别为57.14%—60.78%和0.174 8—0.190 1。10个ISSR引物共扩增出134条带,扩增片断大小为218—2 695 bp,种群的多态性位点比例和遗传多样性指数分别为72.48%—75.22%和0.245 7—0.253 4。RAPD和ISSR分析都表明汕尾与北海翡翠贻贝种群间的遗传距离最大。结果表明,(1)翡翠贻贝种群具有较高的遗传多样性;(2)RAPD与ISSR标记适合于翡翠贻贝遗传多样性分析,但ISSR比RAPD能检测到种群间更高的遗传变异。     

Effects of taxonomic uncertainty on species diversity indices

As a result of taxonomic uncertainty, generic and higher taxonomic ranks (family, order, class or phylum) are often treated as units in calculating diversity indices, instead of species. In this paper, the errors introduced by such practices are examined for various diversity indices (Shannon - Wiener Index, Maximum Information Index, Evenness, Margalef's Species Richness Index and Hurlbert's Probability of Interspecific Encounter). The use of higher taxonomic ranks may invalidate comparison of diversity indices. In a single study, substantial error and erroneous conclusion may arise, even if consistent practices are adopted.     

海上油田功能型聚合物调驱的实验研究

渤海油田油层非均质性严重、油水流度差异大、吸水剖面不均衡,比较适宜采取深部调驱的方式来提高采收率。通过岩心模拟实验对一种新的功能型聚合物GN-1的黏度-浓度关系、流动性能进行了测定,对该聚合物的流体转向能力和调驱效果进行了评价,结果表明其具有良好的调驱能力。使用高浓度的普通聚合物0．1PV＋GN-1聚合物0．15PV组合驱替能有效的动用中低渗透层,大幅度提高采出程度。     

Effects of the pharmaceutical fluoxetine in spiked-sediments on feeding activity and growth of the polychaete Capitella teleta

The marine–estuarine polychaete Capitella is an indicator of organic pollution and plays important roles in sewage waste cycling. The antidepressant fluoxetine can be accumulated in streams and sewage effluents and it could pose a hazard to infauna. Effects of fluoxetine on feeding and growth of Capitella teleta were investigated through the exposure to 0, 0.001, 0.03, 0.3 and 3.3 μg/g dry weight sediment-spiked fluoxetine during 18 days. No effects of fluoxetine concentrations were observed on egestion rates, body weight and size-specific egestion rates. Fluoxetine favoured the occurrence of males with abnormal genital spines. This suggests that fluoxetine can have important reproductive implications. Further studies are recommended to assess potential detrimental effects on benthic infauna inhabiting close to sewage treatment plants.     

舟山近海条石鲷野生群体与人工放流群体遗传多样性的AFLP 分析

利用AFLP技术对舟山近海条石鲷(Oplegnathus fasciatus)野生和放流群体的遗传多样性进行比较分析,旨在为条石鲷的人工增殖及其种质资源的保护和利用提供遗传学的基础资料.采用8对引物组合在2个群体中共扩增得到位点316个,多态性位点为162个,多态性比例为51.67％.野生群体和放流群体的多态性位点比例(P),Nei's基因多样性指数(H)和Shannon's多样性指数(I)分别为46.75％和44.67％,0.097和0.089,0.16和0.15.野生群体的遗传多样性水平略高于放流群体,但差异并不显著(P＞0.05).两群体间的遗传相似系数(S)和遗传距离(D)分别为0.99和0.0073;基因分化系数(Gst)为0.036,群体间无显著遗传分化(P＞0.05).分子方差(AMOVA)分析表明96.82％的遗传变异来源于群体内的个体间,群体间无显著的遗传差异(P＞0.05).以上研究结果表明条石鲷的放流群体与野生群体间无明显的遗传分化,放流群体的遗传多样性水平尚处于一个合理状态.但为了避免放流群体对野生群体产生负面的遗传效应,应当增加放流群体繁育亲本的数量,并对放流群体的遗传变异水平进行持续监测.     

Effects of the invasive polychaete Marenzelleria spp. on benthic processes and meiobenthos of a species-poor brackish system

The effects of the invasive polychaete Marenzelleria spp. on sediment processes and meiobenthos with an emphasis on free-living nematodes of the Vistula Lagoon (southern Baltic Sea) were investigated in a laboratory microcosm experiment. Marenzelleria occupies an open niche and its deep burying behaviour and feeding strategy represent a new function in the study area. Halos of oxidized sediment along Marenzelleria burrow walls indicated oxygen penetration into the burrows but the polychaete had no significant effect on porewater nutrient concentrations. The results showed, however, the density dependent effects of Marenzelleria on ammonium transport. An enhanced ammonium efflux was recorded at high polychaete densities (2000 ind. m^− 2) but not at low polychaete densities (300 ind. m^− 2).There was no observable impact of the polychaete on total meiobenthic numbers. There was, therefore, no indication that Marenzelleria caused meiofauna mortality. On the contrary, the polychaete significantly affected vertical distribution of meiofauna facilitating the colonization of deeper sediment depths and thus extending the habitat to be used by meiobenthos. In addition, Marenzelleria had a positive impact on the survival of turbellarians.Nevertheless, there was no effect of Marenzelleria on nematode assemblage structure and diversity, indicating that neither the physical presence nor the biological activity of the worm affected the nematode community. This suggests either 1. the limited impact of Marenzelleria on nematodes, resulting from the creation of simple, narrow and un-branched burrows, 2. poor response of nematode community resulting from their low abundance and diversity in the study area, or 3. the overriding role of the harsh chemical environment typical of sediments of the Vistula Lagoon, masking the effect of the bioturbator.     

The effect of the dominant polychaete Scolelepis squamata on nematode colonisation in sandy beach sediments: An experimental approach

The effect of an abundant sandy beach polychaete, Scolelepis squamata, on the colonisation of defaunated sediments by marine nematodes indicates that sandy beach fauna can be partially controlled by biological interactions within and across size groups. Experimental cores, equipped with windows allowing infaunal colonisation, were filled with defaunated sandy beach sediment containing two different treatments with and without S. squamata. These cores were inserted into microcosms filled with sediment with indigenous meiofauna collected from the field. The treatments were incubated in the laboratory at ambient temperature and salinity for 2, 7, 14 and 21 days, in order to follow the colonisation process of the defaunated sediments by the indigenous nematode fauna over time. Nematodes initially colonised both treatments, with abundances of up to 10% of the densities in the control; after 2 weeks, nematode densities in the cores without S. squamata surpassed the control densities. Nematode assemblages in both treatments were not species rich, and also differed in composition from the natural assemblages. The most successful colonising species, Enoplolaimus litoralis, was rare in the surrounding sediment, suggesting that colonisation was determined by species-specific characteristics such as body size, motility and feeding strategy. Initially the presence of macrofauna did not affect the nematode community composition, but after 2 weeks of the experiment, the presence of the polychaete seemed to facilitate the earlier establishment of non-opportunistic species.     

Effects of barium and cadmium on the population development of the marine nematode Rhabditis (Pellioditis) marina

Offshore oil and gas drilling often involves the use of fluids containing barium and traces of other heavy metals. These may affect the environment, but information on their toxicity to benthic biota remains scant. Here, we present results of a 10-day bioassay with the marine nematode Rhabditis (Pellioditis) marina at different loads of barium (0-10 ,000 ppm nominal concentrations) and cadmium (0-12 ppm) in the range of concentrations reported from drilling-impacted sediments. Barium did not affect the fitness and population development of R. (P.) marina at concentrations up to 300 ppm, but did cause a decrease in population abundance and an increase in development time from concentrations of 400-2000 ppm onwards. Increased mortality occurred at 4800 ppm Ba. For cadmium, LOEC and EC?? values for total population abundance were 2.95 and 8.82 ppm, respectively. Cd concentrations as low as 2.40 to 2.68 caused a decrease in the abundance of adult nematodes, indicating that assays covering more generations would likely demonstrate yet more pronounced population-level effects. Our results indicate that oil and gas drilling activities may potentially have important implications for the meiobenthos through the toxicity of barium and associated metals like cadmium.     

Effects of iron and humic acid on competition between Microcystis aeruginosa and Scenedesmus obliquus revealed by HPLC analysis of pigments

Iron is a vital micronutrient for growth of bloom-forming Microcystis aeruginosa and competition with other algae, and its availability is affected by humic aci...