Seasonal and areal features of the lagoonal environment in Lake Nakanoumi,a shallow coastal lagoon in Japan

Lake Nakanoumi is a shallow coastal lagoon connected with the Japan Sea by a narrow channel. Over the past decade, land reclamation resulted in a 33% reduction of the lagoon's surface area. The remaining water basin of Lake Nakanoumi is scheduled to be artificially freshened to supply irrigation water for the newly reclaimed lands. This paper deals with the seasonal and areal features of the lagoonal environment prior to the beginning of the artificial desalinization.     

Ecological restoration in coastal areas in the Netherlands: concepts,dilemmas and some examples

This chapter gives an overview of attempts in the Netherlands to restore coastal ecosystems and habitats, and explains how scientific and non-scientific information has been used to meet the goals. Indications for successes and failures of management measures taken so far, as well as dilemmas to cope with, are given. Up to now only small scale restoration projects have been executed, while large scale projects generally are not further then the thinking or planning phase. A special type of `restoration projects' are the large civil engineering works, particularly in the south-west of the Netherlands. Although these works were not planned and executed as restoration projects, but designed for safety against flooding from the sea, they have led to significant changes in the boundary conditions of the systems concerned. For restoration projects yet to be executed one can learn very much from these developments, particularly regarding the sensitivity of coastal systems for changes in boundary conditions and about the (im)possibilities to `steer' ecological developments. Physical, chemical and biological processes form the basis of restoration measures of coastal habitats, and this means that a thorough knowledge of these processes is essential. Coastal ecosystems are the result of complex interactions of large-scale and small-scale processes, implying a holistic approach in scientific investigations. Consequently, restoration of these systems primarily has to be realised by influencing the basic processes. This is the only way to preserve or regain in a sustainable way ecological values, such as species composition. Focusing only at one particular species (e.g. breeding terns) or a specific habitat (e.g. a salt marsh) may easily ignore the underlying processes. In general, coastal restoration should focus on the redirection of processes towards a desired status by stimulating certain process parameters. Monitoring of the results and, if necessary, gradual readjustment of the governing factors, is an essential part of this approach.     

Cave Fauna of Bermuda

Sea-level pools are found in most of Bermuda's known caves. Although the terrestrial fauna of the caves is sparse, a rich aquatic fauna inhabits the pools. While many of the marine cave animals are more or less regular immigrants from open littoral habitats, a number of new species have been discovered, including blind and probably subterranean ones. Zoogeographical connections exist between Bermuda's cave fauna and those of the West Indies and the Mediterranean.     

盐分对河口淡水、微咸水沼泽湿地土壤甲烷产生潜力的影响

海平面上升导致河口区盐水入侵现象日益明显,深刻影响着河口潮汐淡水、微咸水湿地生物地球化学循环。采集闽江河口区淡水、微咸水短叶茳芏潮汐沼泽湿地表层土样,室内添加盐度为5,10,15,21 g/L的人造海水、Na Cl溶液及盐度为0的去离子水,通过室内泥浆厌氧培养试验,对比研究海水和Na Cl溶液对淡水、微咸水沼泽湿地土壤甲烷产生潜力的影响。与对照相比,1—12 d培养期内4个盐度的海水处理均显著抑制河口淡水、微咸水沼泽湿地甲烷产生潜力,抑制率在93%以上,盐度10—21 g/L的3个海水处理对于河口淡水、微咸水沼泽湿地甲烷产生潜力的抑制效应无显著差异。Na Cl溶液只有在盐度达到15和21 g/L才显著抑制淡水、微咸水沼泽湿地甲烷产生潜力,且抑制率最多为80.9%,盐度为5、10 g/L的Na Cl溶液对淡水、微咸水沼泽湿地甲烷产生潜力的抑制作用不显著,抑制率多小于30%。伴随着盐水入侵而发生的硫酸盐还原作用及离子胁迫作用对河口淡水、微咸水沼泽湿地甲烷产生具有显著的抑制效应。     

Copepods of the Genus Oithona Baird, 1843 from mangrove areas of Central and South America

The distribution of the cyclopoid Genus Oithona in waters bordered by mangroves along the coast of Central and South America was studied. Of the ten species previously registered only O. hebes Giesbrecht, O. oswaldocruzi Oliveira, O. alvarezi Lindberg and O. fonsecae Ferrari & Bowman remain valid. O. hebes and O. oswaldocruzi are redescribed and their synonymies extensively discussed. No representatives of O. alvarezi and O. fonsecae were examined.Integumental pore signature patterns of oithonid females are described for the first time. The importance of the pore signature of the cephalosomic flaps of the males as a taxonomic character is discussed.     

Adaptation to sea level rise: does local adaptation influence the demography of coastal fish populations?

This study compared the growth of two western mosquitofish Gambusia affinis populations that were previously demonstrated to have genetic adaptations that increased survival under lethal salinity exposures. The objective was to evaluate how genetic adaptations to lethal salinity stress affect population demography when exposed to sublethal salinity stress. Results indicate that chronic salinity exposure had a generally negative impact on population size, but fish originating from one of the two populations established with fish from a brackish site exhibited an increase in population size. Saltwater intrusion seems to result in reduced population size for most populations. Some populations inhabiting more saline sites, however, may develop localized adaptations, mitigating the consequences of increased salinity on population productivity.     

Eutrophication and Restoration Measures in the Darß-Zingst Bodden Chain

The Darß-Zingst Bodden chain, part of the brackish inner coastal waters of Mecklenburg-Vorpommern, Germany, is supplied by large amounts of phosphorus and nitrogen from the catchment area. Due to the shallowness an additional nutrient input is realized via sediment-water interactions. The results are highly eutrophicated water bodies. But in contrast to other systems the actual nutrient concentrations are mainly influenced by hydrographical features and don't reflect the loading situation. Possible rehabilitation methods are discussed for the Bodden chain handling, especially the sediment problem.     

稳定碳同位素在滨海湿地碳生物地球化学循环中的应用

碳作为滨海湿地中重要的生命元素,其生物地球化学循环过程是滨海湿地研究的核心内容之一.稳定同位素技术越来越多地被应用到滨海湿地碳生物地球化学循环过程的研究中,提高了其研究水平,并推动了其研究的进程.本文从有机物质生产、土壤有机质来源、食物链传递、温室气体排放以及可溶性有机碳输出5个方面,综述了滨海湿地碳生物地球化学循环过程的稳定同位素研究进展.通过植物及土壤δ13C值的测定进行有机质的生产机理研究及外源追溯,通过对比各生物种群的δ13C值分析碳在生态系统中的流动过程,通过湿地排放温室气体及可溶性有机碳δ13C值的测定揭示影响碳输出的环境因子.最后,文章总结了当前研究中存在的问题,并对其研究前景进行了展望.     

Small Players, Large Role: Microbial Influence on Biogeochemical Processes in Pelagic Aquatic Ecosystems

Although prokaryotes are small in size, they are a significant biomass component in aquatic planktonic ecosystems and play a major role in biogeochemical processes. A review of the recent literature shows that the relative importance of prokaryotes to material and energy fluxes is maximized in low-productivity (oligotrophic) ecosystems and decreases in high-productivity (eutrophic) ecosystems. We conclude that competition with eukaryotic autotrophs for dissolved nutrients and competition with phagotrophic heterotrophs and physical processes (sinking, photooxidation) for organic carbon (C) play important roles in determining the relative abundance and impact of prokaryotes in aquatic systems. Oligotrophic systems have low nutrient concentrations, with high proportions of dissolved nutrients in organic form, which favors prokaryotic heterotrophs over phytoplankton. Furthermore, a high proportion of the available organic C is dissolved rather than particulate, which favors prokaryotic heterotrophs over phagotrophic heterotrophs. In eutrophic systems, increased relative concentrations and loading of inorganic nutrients and increased relative concentrations of particulate organic C select for phytoplankton and phagotrophic heterotrophs over prokaryotic heterotrophs. Increased particle sinking fluxes and/or decreased excretion of organic carbon (EOC) may also decrease the relative importance of prokaryotic heterotrophs in eutrophic systems. In oligotrophic systems, interactions between autotrophs and heterotrophs are tightly coupled because the dominant heterotrophs are similar in size and growth rates, as well as having similar nutrient composition to the dominant autotrophs, small phytoplankton. In eutrophic systems, increased productivity passes through zooplankton that are larger and have slower growth rates than the autotrophs, leading to a greater potential for decoupled auto- and heterotrophic production and increased export production. Received 18 July 2000; Accepted 13 September 2001.     

Effects of sand bar openings on some limnological variables in a hypertrophic tropical coastal lagoon of Brazil

This study describes the spatial and temporal dynamics of several physical, chemical and biological variables in the Grussai lagoon, and their relationship to ephemeral sand bar openings and to a constant in natura waste water input. The spatial variation in pH, dissolved oxygen, electrical conductivity, total alkalinity and nutrients (e.g. soluble reactive silicate, soluble reactive phosphate and ammonium) was associated to the anoxic and nutrient rich groundwater discharge, the development of aquatic macrophytes, the biological activities of phytoplanktonic community and the marine influence. During the period when the sand bar was closed (isolated), the lagoon water was supersaturated with dissolved oxygen and exhibited high values of pH (8–10), total alkalinity (3.000–5.000 μeq l^-1), and chlorophyll a contents (60-300 μg l^-1), and had low values of dissolved nutrients (nearly undetectable). These suggest a biological processes dominance. When the sand bar was opened, there was an enrichment with dissolved inorganic nutrients (e.g. ammonium and soluble reactive phosphorus up to 120 and 5 μM, respectively) and a decrease in pH (below 8), total alkalinity (below 3.000 μeq l^-1) and dissolved oxygen during the initial second to eight days. Subsequently there was a period when the physical and chemical characteristics of seawater prevailed. The lagoon returned chemical to the pre-opening water conditions in a few days (∼ 10–20). This quick return implies highly efficient biological mechanisms. The high levels of chlorophyll a, total nitrogen and phosphorus in the water column indicate a high eutrophication stage in the Grussai lagoon during the sand bar closed periods. This revised version was published online in July 2006 with corrections to the Cover Date.     

Metagenomic mining for microbiologists

Microbial ecologists can now start digging into the accumulating mountains of metagenomic data to uncover the occurrence of functional genes and their correlations to microbial community members. Limitations and biases in DNA extraction and sequencing technologies impact sequence distributions, and therefore, have to be considered. However, when comparing metagenomes from widely differing environments, these fluctuations have a relatively minor role in microbial community discrimination. As a consequence, any functional gene or species distribution pattern can be compared among metagenomes originating from various environments and projects. In particular, global comparisons would help to define ecosystem specificities, such as involvement and response to climate change (for example, carbon and nitrogen cycle), human health risks (eg, presence of pathogen species, toxin genes and viruses) and biodegradation capacities. Although not all scientists have easy access to high-throughput sequencing technologies, they do have access to the sequences that have been deposited in databases, and therefore, can begin to intensively mine these metagenomic data to generate hypotheses that can be validated experimentally. Information about metabolic functions and microbial species compositions can already be compared among metagenomes from different ecosystems. These comparisons add to our understanding about microbial adaptation and the role of specific microbes in different ecosystems. Concurrent with the rapid growth of sequencing technologies, we have entered a new age of microbial ecology, which will enable researchers to experimentally confirm putative relationships between microbial functions and community structures.