Biodiversity patterns of free-living marine nematodes in a tropical bay: Cienfuegos, Caribbean Sea

Spatial and temporal biodiversity patterns of free-living marine nematodes were studied in Cienfuegos Bay, a tropical semi-enclosed basin in the Caribbean Sea. Taxonomic (to species level) and functional (biological trait) approaches were applied for describing the assemblage structure and relating it to abiotic environment based on a sampling scheme in six subtidal stations and three months. Biological trait approach added relevant information to species pattern regarding relationships between diversity patterns and the abiotic environment. The most common morphotypes were deposit feeding nematodes, with colonising abilities of 2–3 (in a scale from 1 to 5), tail conical cylindrical or filiforme and body slender; and their abundance were correlated with depth, organic matter and silt/clay fraction. In spite of a high turnover of species, functional diversity of assemblages did not change notably in space and time. A result probably due to sampling of the habitat pool of species and to low heterogeneity of the studied muddy bottoms. Chemical pollution (organic enrichment and heavy metals) and hydrodynamic regime possibly drove the biodiversity patterns. Spatial distribution of assemblages support the existence of two well differentiated basins inside the bay, the northern basin more polluted than the southern one. The low hydrodynamic regime would determine a poor dispersion of nematodes resulting in high spatial variance in the assemblage structure; and also the associated hypoxic conditions and pollutants in sediments can explain the dominance of tolerant nematode species such as Daptonema oxycerca, Sabatieria pulchra, Terschellingia gourbaultae, and Terschellingia longicaudata. A comparison of spatial–temporal patterns of biodiversity between Cienfuegos Bay and other semi-enclosed bays in temperate regions suggests several similarities: nematode assemblages are strongly influenced by anthropogenic disturbance, temporal trends are weak or overridden by spatial ones, and few cosmopolitan genera/species tolerant to pollution and hypoxic conditions are dominant.     

Does suspended matter drained from the Isahaya freshwater reservoir cause organic enrichment in the northern Ariake Bay?

The inner part of Isahaya Bay was converted to a freshwater reservoir following the closure of the land claim dike in 1997. Turbid water drains into Isahaya Bay when water levels increase. We investigated whether particulate organic matter (POM) from the reservoir in Isahaya Bay has caused bottom organic enrichment in the northern part of Ariake Bay. Using potential end-members from before to after the rainy seasons, during which a frequent discharge from the reservoir was expected, stable isotope analyses were performed on sediments collected from Isahaya Bay and northern Ariake Bay. Each end-member was isotopically differentiated by δ¹³C and δ¹⁵N (riverine POM: ?28.5 to ?27.2‰ and 3.3–4.6‰; reservoir POM: ?25.7 to ?25.3‰ and 7.4–8.4‰; marine POM: ?21.8 to ?19.7‰ and 6.7–7.6‰; microphytobenthos estimated from consumers: ?16.1 to ?15.9‰ and 5.2–6.1‰, respectively). Sediment isotopic signatures fell within the mixing space defined by the signatures of the end-members. Marine POM contributed greatly to bottom sediments in both seasons in Isahaya Bay and Ariake Bay, ranging from ca. 60–70 and 40–60%, respectively. Reservoir POM contributed around 10% to bottom sediments. This percentage slightly increased in the sediment of Isahaya Bay after the rainy season, but decreased in the sediment of Ariake Bay. Thus, most of the POM discharged from the reservoir would not reach the northern part of Ariake Bay and would not be a major contributor to organic enrichment. This study is the first to quantitatively describe the contribution of drained reservoir POM outside Isahaya Bay.     

Meiofauna in a cold-seep community off Hatsushima,central Japan

The community structure of the bathyal meiofauna of a cold-seep community found off Hatsushima in Sagami Bay, central Japan, was compared with the community composition outside the influence of the seep, using sediments collected during dives 226 and 227 of the deep-sea submersibleShinkai 2000. The sediment from the Hatsushima seep site (HSS) was very coarse, black in color, and with an odor of hydrogen sulfide, suggesting reduced thiobiotic conditions. The sediment from the control area was well-oxygenated, fine silt. Despite the differences in the characteristics of the sediments, the abundance of meiofauna in the HSS was not very different from that in the control area. However, its composition even at the major taxonomic group level was distinct; for example, a high nematode/copepod ratio occurred in one of the samples collected at the HSS. At the species level, nematodes were less diverse at the HSS than at the control area. The composition of the nematode fauna at the HSS showed stronger affinity with that collected at the adjacent control area than with a community sampled from other deep-sea environments or another seep community in shallow water. This emphasizes that the adaptation of nematodes to the thiobiotic condition is controlled by local conditions.     

Chemical speciation of arsenic in different marine organisms: Importance in monitoring studies

Arsenic is a widely distributed element in the marine environment. Inorganic and organic compounds have extremely different toxicological effects, and their characterization is thus of great utility when monitoring and assessing the impact of arsenic pollution. In this study both the levels of total arsenic and its chemical speciation were analyzed in several marine organisms collected from Cienfuegos Bay (Cuba) following an episode of acute As-contamination. Fish from the more impacted site were characterized by elevated concentrations of arsenic (up to 500 microg/g d.w.) and inorganic species represented the predominant forms in muscle tissues of these organisms.     

Composition and distribution of meiobenthos in amursky bay (peter the great bay, the east sea)

Qualitative and quantitative composition of meiobenthos was studied in Amursky Bay (Peter the Great Bay, the East Sea). Ten taxonomic groups were found, where nematodes were dominant. Density of meiobenthos in ground sediments of the Bay were not uniform, and the average density was measured at 126.4±62.3 ind. m^-2. 56 species of nematodes were detected, and dominant species wereSabatieria palmaris, Paracanthonchus macrodon, Sphaerolaimus limosus, S. gracilis andOncholaimium ramosum. Five taxocenes of nematodes were allocated based on the results of cluster analysis and species domination according to density. Low diversity in species composition of nematodes was noted in the northwestern part of the Bay, which is a zone of desalination, and in the eastern part, which is exposed to household drains.     

应用有机碳同位素技术研究湛江湾生态环境的变化过程

随着工业化进程的加快,湛江湾的生态环境承载力受到了极大的考验。为了解湛江湾生态环境的变化过程,文中利用湛江湾表层柱状沉积物样品中总有机碳含量(TOC)及其稳定同位素、总氮含量(TN)和C/N值的测定,结合端元混合模型,分析了湛江湾沉积物中有机质的来源,探讨了沉积物有机碳同位素的主要影响因素。结果表明,湛江湾沉积物中有机质主要来源为自生藻类,同时也受一定程度陆源输入的影响。沉积序列的元素地球化学参数表明,沉积物δ13C值呈现短暂的负偏随后长期正偏的趋势。底部的负偏可能与大气CO2浓度增加有关,随后δ13C主体正偏的趋势主要受控于气候转暖、生产力增加以及富营养化程度增加的共同影响,暗示了人类活动对湛江湾的生态环境的影响逐渐加剧。其中,人类活动相关的工业、农业有机污染物排放可能是不断加剧海水富营养化的主要原因。     

用海洋线虫监测潮间带有机质污染的调查研究

本文是1990年6月至12月,在青岛湾东侧的泥质—粉砂质潮间带,对小型底栖生物所进行的定量研究。小型动物的丰度,随季节变化很大,从9月的909ind/10cm~2至6月的9850ind/10cm~2。自由生活海洋线虫占整个小型动物数量的99.8％。线虫的最低值出现在严重污染区的S_4站。6月在污染区的S_2站观察到。线虫的最高值21427ind/10cm~2。SCI指数随远离排污口而增加。沿有机质污染的梯度,海洋线虫的丰度和SCI指数所显示的趋势,与本研究及以前所获得的大型多毛类动物(主要是小头虫)的研究结果相吻合。将海洋线虫的丰度、百分比组成和SCI指数,做为一种可行的方法,可用来监测受到有机质污染的沉积物。     

福建省兴化湾、九龙江河口和东山湾潮间带沉积物岩心碘研究

用碱熔法处理样品,水沥取,用分光光度法测量了采集自福建省兴化湾、九龙江河口和东山湾3个海湾潮间带沉积物岩心的碘分布。兴化湾、九龙江河口和东山湾3岩心中的碘含量分别为2.5~43.7,17.3~39.6和11.3~29.1 mg/kg。3个沉积物岩心中的碘含量稍高于福建省的土壤的碘含量,与我国海域的沉积物碘含量在同一水平,但明显低于文献报道的开阔海域沉积物的碘含量。兴化湾和东山湾沉积物中的碘与有机碳含量有较好的相关性;在九龙江河口采集的岩心中的碘与有机物碳含量的相关性较差。推测海洋源的沉积物碘与有机碳含量相关性较好,而陆源沉积物的碘与有机碳含量相关性较差。     

Geochemistry of muds from a shallow restricted estuary,Australia

Sediments from a shallow, restricted estuary in southeast Australia were analysed for Ti, V, Cr, Mn, Fe, Co, Cu, Ni, Zn, P₂O₅ and organic carbon. Subjective interpretation of factor analysis on a geochemical basis, indicates that the dominant controls on the distribution and concentration of these metals and P₂O₅ in the mud sediments are the mineralogy of land-derived detritus and the chemical conditions of the environment in which the sediments are deposited. None of the transition-metal contents of the sediments, apart from Cr and possibly Cu, can be directly attributed to enrichment over that due to areal variation in detrital mineralogy. Chromium may be precipitated from the water column as a hydroxide in reducing environments, and Cu may be supplied to some extent by organic matter. Phosphate is enriched in the sediment through its association with organic matter. Manganese concentrations are depleted from the surface sediments of reducing environments. Iron sulphide and associated Ni and Zn sulphides are probably formed largely through early diagenetic reactions involving the mobilization of these metals from detrital mineral phases into authigenic phases. Evidence for the presence of these authigenic phases is found in sediments from areas where reducing conditions are likely to be most prevalent.     

Meiobenthos under mariculture conditions of the brown seaweed <Emphasis Type="Italic">Saccharina japonica</Emphasis> in Rifovaya Bay,Peter the Great Gulf,Sea of Japan

The qualitative and quantitative compositions of free-living marine nematodes were studied in Rifovaya Bay (Peter the Great Gulf, Sea of Japan). It was found that the density distribution of nematode populations in bottom sediments of Rifovaya Bay is nonuniform. In total, 72 nematode species were found, including Oncholaimium paraolium, Viscosia epapilosa, and Monoposthia latiannulata on all types of substrates. The dominant trophic group comprised “predators” (2B) and “scrapers” (2A). It was shown that the species composition of nematodes in Rifovaya Bay is very similar to the species composition of nematodes in the other areas of Peter the Great Gulf.     

乳山湾外低氧海域沉积物中有机碳、氮、磷及其形态特征分析

根据2009年8月在乳山湾及其毗邻海域的综合调查,分析了该海域表层沉积物中有机碳、氮、磷含量及其组成形态的变化,初步探讨了影响底质理化参数变化的原因及对乳山湾外近岸底层低氧形成的影响.结果表明,乳山湾外近海为粉砂质岸滩,以细颗粒为主;底质中有机碳含量介于0.49％ ～0.93％,平均值为0.69％;总氮含量介于382～1020 mg/kg,平均值为671 mg/kg;可溶性总氮含量介于23.0 ～ 60.0 mg/kg,平均值为44.0mg/kg,其中可溶性有机氮和氨氮分别占可溶性总氮的58.8％和38.8％;总磷含量介于138～769 mg/kg,平均值为356 mg/kg,有机磷是占有绝对优势的磷形态(62.5％).研究区域沉积物中总氮和湾内相当,有机碳、总磷含量普遍低于乳山湾内,但均明显高于南黄海区域,且呈还原性状态.调查区域内沉积物中相对较高的有机碳、氮、磷可能是在潮流作用下乳山湾与外海的物质交换所致,其耗氧过程是导致底层溶解氧亏损的重要原因,值得进一步关注.     

Distribution and sources of heavy metals in the sediment of Xiangshan Bay

Heavy metals in the surface sediments and sediment core from the Xiangshan Bay, a mariculture base on the coast of the East China Sea, were determined by inductively coupled plasma mass spectrometry(ICP–MS) in order to evaluate their levels and sources. The results showed that the levels of Cu, Pb, Zn, and Cr in the sediments of the bay have been generally influenced by anthropogenic inputs since the founding of the People's Republic of China. In particular, Cu and Zn were polluted to some extent, as evidenced by high enrichment factors. Organic matter, grain size, wastewater discharge, and low energy hydrodynamic environment played dominant roles in the heavy metal enrichment in the sediments. The ratio of terrigenous source to marine biogenic deposit of trace metals in the sediments was calculated, revealing that terrigenous inputs were the main source of Cu, Pb, and Zn, while biological pellets contributed much more to the enrichment of Cr and Cd. Considering the influence of biological sources on the enrichment of Cd and Cr, and the fact that the sediment has been polluted by Cu and Zn, the development of mariculture and discharge of wastewater into the Bay should be restricted.     

胶州湾潮间带沉积物主要污染来源及分布特征

系统地在胶州湾潮间带获取表层沉积物样品,对沉积物中有机污染物(有机质、石油类),重金属(Hg,Cu,Pb,Zn,Cd,Cr,As)及硫化物进行了定量测定;对潮间带中各物质的主要污染来源和空间分布特征进行了分析。结果表明:胶州湾潮间带沉积物中主要污染分别来源于工业排污和生活污水的排放,交通污染的降水、降尘等。调查区重金属对该海域的生态危害程度从大到小为HgAsCuCdPbCrZn,与其他海域相比较,胶州湾潮间带中Hg和Cu的污染尤为突出。     

大亚湾表层沉积物中重金属分布特征

为了解大亚湾沉积物中重金属分布及污染状况,于2016年8月对大亚湾海域表层沉积物中重金属元素（As、Cd、Cr、Pb、Zn和Cu）展开调查,并将获得的各元素含量与粒度、Fe、Mn和总有机碳（TOC）等相关理化要素进行相关性分析。结果表明：大亚湾沉积物中重金属受陆源输入影响较大,含量基本呈现为沿岸高、湾内低的趋势,总体质量较好,基本符合第一类海洋沉积物质量标准要求;澳头湾和范和港附近海域人类活动密集,重金属含量较高。通过相关性分析结果发现,大亚湾重金属主要来源为岩石的风化和侵蚀、工业污水排放和渔业养殖等;Cu与铁锰氧化物结合性弱于其他元素,在还原性环境中被沉积物吸附形成金属Cu硫化物可能是喜洲岛附近海域Cu元素含量异常高值的原因;作为湾内有机质主要来源的水生浮游生物的生长状态对Cr、Zn和Pb含量影响较大;Cr、As和Pb与粉砂结合为主,Zn与粘土结合为主。     

Meiobenthos in estuary part of ha long bay (gulf of tonkin, south china sea, vietnam)

The distribution of the taxonomical composition and the density of meiobenthos depending on some factors of environment has been studied in bottom sediments of the northern estuary part of Ha Long Bay (Cua Luc estuary). The basic factor of influence on meiobenthic community structure was the granulometric composition of sediment. The greatest taxonomic diversity is noted in the silted sands, lowest — in the silty sediments. The density of meiobenthic community was higher in the silty sediments. Slightly expressed correlation between the density of nematodes and the percentage of silty particles in the sediments is detected (Spearman rank correlation coefficient was 0.49±0.21, p=0.035). The nematodes were dominant at all stations. In total, representatives of 66 species of nematodes belonging to 17 families and 52 genera were identified.     

海南岛近海表层沉积物分散元素的富集特征与污染评价

对海南岛周边海域表层沉积物中7种分散元素镓(Ga)、锗(Ge)、铷(Rb)、铊(Tl)、镉(Cd)、碲(Te)和硒(Se)的分布与富集特征,及其与沉积物粒度、总有机碳和有机氮的相关性进行了较系统的分析,并分别利用内梅罗综合指数法和污染负荷指数法对这些元素的污染情况进行了初步评价。结果表明,分散元素的富集与沉积物粒度、有机碳和有机氮的含量有密切关系,除Te外,其它6种分散元素均表现出在粉砂或黏土质,以及有机碳和有机氮含量高的沉积物中趋于富集;沉积物的分散元素污染总体上呈轻微程度,但在局部海域(如海南岛西北部、西部、东南部近海海域以及陵水和三亚段海域)接近中等污染程度,说明这些区域受人类活动的影响较大,应引起海洋环境保护主管部门的重视。     

Historical contamination of PAHs, PCBs, DDTs, and heavy metals in Mississippi River Delta, Galveston Bay and Tampa Bay sediment cores

Profiles of trace contaminant concentrations in sediment columns can be a natural archive from which pollutant inputs into coastal areas can be reconstructed. Reconstruction of historical inputs of anthropogenic chemicals is important for improving management strategies and evaluating the success of recent pollution controls measures. Here we report a reconstruction of historical contamination into three coastal sites along the US Gulf Coast: Mississippi River Delta, Galveston Bay and Tampa Bay. Within the watersheds of these areas are extensive agricultural lands as well as more than 50% of the chemical and refinery capacity of the USA. Despite this pollution potential, relatively low concentrations of trace metals and trace organic contaminants were found in one core from each of the three sites. Concentrations and fluxes of most trace metals found in surface sediments at these three sites, when normalized to Al, are typical for uncontaminated Gulf Coast sediments. Hydrophobic trace organic contaminants that are anthropogenic (polycyclic aromatic hydrocarbons, DDTs, and polychlorinated biphenyls) are found in sediments from all locations. The presence in surface sediments from the Mississippi River Delta of low level trace contaminants such as DDTs, which were banned in the early 1970's, indicate that they are still washed out from cultivated soils. It appears that the DDTs profile in that sediment core was produced by a combination of erosion processes of riverine and other sedimentary deposits during floods. Most of the pollutant profiles indicate that present-day conditions have improved from the more contaminated conditions in the 1950-1970's, before the advent of the Clean Water Act.     

Oxygen and Sulfides in Bottom Sediments of the Coastal Sevastopol Region of Crimea

Spatial variations in the distribution and fluxes of dissolved oxygen and sulfide in bottom sediments of Omega and Sevastopol bays have been studied. The results of analysis reveal that the distribution of dissolved oxygen and sulfide in pore water depends mostly on seasonal variations in the oxygen concentration in bottom water, grain size, the organic carbon content in bottom sediments, and, additionally for Sevastopol Bay, the iron content. The oxygen flux at the bottom of Sevastopol Bay is 20 times larger in winter–spring compared to that of Omega Bay. Anaerobic conditions in Sevastopol Bay sediments are observed much closer to the surface, with their subsequent development in bottom water.     

渤海湾氮、磷营养盐在水体和沉积物中的分布特征及其相互关系

近岸海域水体和沉积物是营养盐迁移转化的重要场所。2016年8月对渤海湾水体和沉积物进行采样监测,分析了渤海湾水体和沉积物中不同形态氮、磷的含量,并研究了营养盐在水体和沉积物中的分布特征及其相互关系。结果表明:渤海湾水体中的营养盐在西部近岸地区含量较高,而在离海岸线较远的开阔海域含量较低,表现出一个明显的质量浓度梯度。说明人类活动对近岸海域水体中营养盐含量的贡献较为明显。水体中营养盐主要是以无机态为主,无机氮和无机磷分别占到总氮和总磷的76.65%和76.46%。沉积物中氮、磷营养盐表现出和水体中营养盐含量类似的空间分布特征,但形态主要以有机氮为主,无机磷的含量也仅占到30.42%。这说明夏季渤海湾水体中氮、磷营养盐主要由水中有机体通过同化作用将无机态营养盐合成为有机态营养盐进入沉积物,渤海湾西北海域的富营养化过程是水体中营养盐向沉积物迁移的一个主要驱动力。     

Contrasting mercury and manganese deposition in a mangrove-dominated estuary (Guaratuba Bay, Brazil)

Sediment cores were taken at seven sites along the mangrove-bound Guaratuba Bay estuary (southern Brazil), with the purpose of assessing conditions controlling Hg deposition along a horizontal estuarine sediment gradient. The data suggest contrasting depositional patterns for Hg and Mn in this relatively pristine setting. Total Hg contents of bulk sediments ranged from 12 to 36 ng/g along the estuary, the highest values being found in muddier organic-rich sediments of the upper estuary (the corresponding mud gradient is 12 to 42 wt.%, and the organic matter gradient 4 to 10 wt.%). Thus, the deposition of fine sediments relatively enriched in mercury occurs primarily in closer proximity to the freshwater source. The data also indicate a reverse gradient in reactive Mn contents, ranging from 29 to 81 μg/g, and increasing seaward. This implies that reactive Mn is mobilized from fine-grained reducing mangrove forest sediments in the upper estuary, and deposited downstream in sandier, oxygen-rich nearshore sediments. These results suggest that mangrove-surrounded estuaries may act as barriers to mercury transport to coastal waters, but as a source of manganese. The present findings also imply that reactive Mn may be used as an indication of Hg depositional patterns in other similar coastal sedimentary settings.