Pyrithiones as antifoulants: Environmental fate and loss of toxicity

The environmental fate and the loss of toxicity of two important antifouling actives, zinc pyrithione (ZnPT) and copper pyrithione (CuPT), were investigated using a bioassay study and an outdoor microcosm study. The bioassay used inhibition of the growth of a marine diatom (Amphora coffeaeformis) to measure the toxicity of ZnPT and CuPT over time in sterile, natural, and sediment-supplemented seawater. In natural seawater and sediment-supplemented seawater in the dark and in sterile seawater exposed to light, growth inhibition was reduced at rates corresponding to the rapid degradation rates for ZnPT and CuPT measured in previous aquatic metabolism, die-away, and photolysis studies. Similarly, the bioassay results from sterile seawater in the dark were consistent with the slower degradation rates measured in abiotic hydrolysis studies. In addition to corroborating the rapid degradation of pyrithione upon exposure to light or sediment, the loss of toxicity indicated that the degradation products were not toxic at the concentrations produced from the dose, which was much higher than predicted environmental concentrations. To supplement environmental fate studies designed to elucidate single-pathway transformations, a microcosm study was conducted to integrate all of the degradation pathways. The study used two sediment and water systems, one of which was dosed during the day and the other at night. The pyrithione degraded rapidly in the water phase, with very little accumulation in the sediment. 2-Pyridine sulfonic acid (PSA) and carbon dioxide were the only detectable degradation products 30 d after dosing. Aquatic toxicity studies with PSA showed no observable effect at concentrations at least three orders of magnitude higher than those for either ZnPT or CuPT. As a result, the worst-case environmental concentration of PSA is expected to be far below the no observable effect concentration.     

The environmental fate and behaviour of antifouling paint booster biocides: A review

Antifouling paint booster biocides are a group of organic compounds added to antifouling paints to improve their efficacy. They have become prevalent since the requirement for alternative antifouling paints formulations for small boats (< 25 m). This need followed a ban on the use of triorganotin biocides in antifouling paints for small boats, in the late 1980's. Worldwide, around eighteen compounds are currently used as antifouling biocides, viz. benzmethylamide, chlorothalonil, copper pyrithione, dichlofluanid, diuron, fluorofolpet, Irgarol 1051, Sea‐Nine 211, Mancozeb, Polyphase, pyridine‐triphenyl‐borane, TCMS (2,3,5,6‐tetrachloro‐4‐methylsulfonyl) pyridine, TCMTB [2‐(thiocyanomethylthio)benzothia‐zole], Thiram, tolyfluanid, zinc pyrithione (ZPT), ziram and Zineb. Any booster biocide released into the environment is subjected to a complex set of processes. These processes include transport mechanisms, transformation, degradation, cross media partitioning, and bioaccumulation. This paper reviews the fate and behaviour data currently available in the public domain concerning antifouling paint booster biocides.     

Pyrithiones as antifoulants: Environmental chemistry and preliminary risk assessment

Pyrithiones are widely used as bactericides, fungicides, or algicides in a variety of products such as shampoos, metal working fluids, adhesives, sealants, and coatings. This broad antimicrobial activity, along with low water solubility and favorable environmental chemistry, makes zinc pyrithione and copper pyrithione potentially ideal replacements for TBT in marine antifouling paints. Several studies on the toxicity and environ- ? mental fate of these pyrithiones have been conducted in freshwater and saltwater systems. Environmental fate studies show that pyrithiones rapidly degrade in the water column to less toxic compounds. Sediment accumulation is also prevented by the facile reduction of a critical functional group under anaerobic conditions. Modeling programs were used to calculate the predicted environmental concentration (PEC) for pyrithione. Comparison of PECs calculated for more persistent antifoulants with actual measured concentrations provided a measure of the bias inherent to the models. The results indicate a pyrithione risk quotient (PEC/PNEC) < 1. The findings are consistent with the absence of ecological effects during the long history of the use of zinc pyrithione as an antidandruff agent.     

Pyrithiones as antifoulants: environmental fate and loss of toxicity

The environmental fate and the loss of toxicity of two important antifouling actives, zinc pyrithione (ZnPT) and copper pyrithione (CuPT), were investigated using a bioassay study and an outdoor microcosm study. The bioassay used inhibition of the growth of a marine diatom (Amphora coffeaeformis) to measure the toxicity of ZnPT and CuPT over time in sterile, natural, and sediment-supplemented seawater. In natural seawater and sediment-supplemented seawater in the dark and in sterile seawater exposed to light, growth inhibition was reduced at rates corresponding to the rapid degradation rates for ZnPT and CuPT measured in previous aquatic metabolism, die-away, and photolysis studies. Similarly, the bioassay results from sterile seawater in the dark were consistent with the slower degradation rates measured in abiotic hydrolysis studies. In addition to corroborating the rapid degradation of pyrithione upon exposure to light or sediment, the loss of toxicity indicated that the degradation products were not toxic at the concentrations produced from the dose, which was much higher than predicted environmental concentrations. To supplement environmental fate studies designed to elucidate single-pathway transformations, a microcosm study was conducted to integrate all of the degradation pathways. The study used two sediment and water systems, one of which was dosed during the day and the other at night. The pyrithione degraded rapidly in the water phase, with very little accumulation in the sediment. 2-Pyridine sulfonic acid (PSA) and carbon dioxide were the only detectable degradation products 30 d after dosing. Aquatic toxicity studies with PSA showed no observable effect at concentrations at least three orders of magnitude higher than those for either ZnPT or CuPT. As a result, the worst-case environmental concentration of PSA is expected to be far below the no observable effect concentration.     

The influence of mesh size in environmental quality assessment of estuarine macrobenthic communities

The Water Framework Directive (WFD) strengthened the need for environmental quality assessment with rapid and accurate results. Studies of estuarine benthic macrofauna communities often use 0.5-mm mesh sieves in samples processing. However, this represents a considerable increase in sampling and identification effort compared to the use of 1-mm mesh sieves. Therefore, it is relevant to determine if mesh size matters in environmental quality assessments.The objectives of this study were as follows: (i) to test whether sieves with different mesh sizes provided different environmental status assessments in transitional systems, (ii) to compare the performance of different ecological indicators based on data from 0.5- and 1-mm mesh sieves and (iii) to compare the costs involved in using these two mesh sizes.Data were collected in the fall of 2007 and winter of 2008 at four sampling stations located in the Mondego Estuary, Portugal. The relative performance of Margalef and Shannon–Wiener indices, AMBI—AZTI Marine Biotic Index, Pielou, Eco-Exergy and Specific Eco-Exergy indices was analysed. Additionally, the multimetric Benthic Assessment Tool (BAT) was applied. The samples from the 1-mm mesh sieve were processed 2.9 times faster than the samples from the 0.5-mm mesh sieves. As expected, the density, biomass and number of species retained in the 0.5-mm mesh sieve were significantly higher in both seasons than the density, biomass and number of species retained in the 1-mm mesh sieve. All indicators were significantly different for the two mesh sizes in at least one season. The Pielou index was significantly different for the two mesh sizes in both seasons. Most indices showed that the 0.5-mm mesh sieve captured more information from the study system. The first BAT analysis provided different Ecological Quality Status (EQS) assessments for the two mesh sizes. To use the EQS obtained from the 1-mm mesh sieve as a proxy for the EQS for the 0.5-mm mesh sieve, further modifications were done in terms of reference conditions and class boundary thresholds. Regarding the Mondego Estuary, the use of a 1-mm mesh sieve appeared to be advantageous on routine environmental quality assessment, giving unbiased results with relatively less effort. Nevertheless, the methodology needs further validation and additional tests.     

Comparison of Four Species Sensitivity Distribution Methods to Calculate Predicted No Effect Concentrations for Bisphenol A

Bisphenol A (BPA, CAS RN 80-05-7) is a high production volume chemical used as an intermediate in the production of polycarbonate plastic and epoxy resins. During its manufacture and use, some emissions to surface waters are anticipated. Chronic predicted no effect concentrations (PNECs) for aquatic systems are used to support the assessment of potential risks to aquatic organisms in receiving waters. PNECs for a compound are considered protective of populations, communities, and ecosystems. Traditionally, PNECs are derived by taking the lowest no-observed effect concentration (NOEC) from a set of toxicity studies and dividing by an assessment factor (e.g., 10 to 1000). This traditional approach is appropriate for substances with few data, but may not be necessary for substances with many valid studies. For well-studied substances, statistical approaches (i.e., development of Species Sensitivity Distribution or SSD methods) can be used to calculate a PNEC that makes use of the full distribution of available NOEC values. Bisphenol A has an extensive set of aquatic toxicity studies covering diverse taxa including algae, hydra, rotifers, mollusks, crustaceans (both benthic and pelagic), insects, annelids, fish, and amphibians. The full chronic data set was used to calculate PNEC values using four SSD methods: (1) the Hazard Concentration (HC5) approach developed by The Netherlands National Institute of Public Health and the Environment (RIVM), (2) the U.S. Environmental Protection Agency's water quality criteria procedure, (3) SigmaPlot (Systat 2000) commercial software that calculates percentile values, and (4) a distributional method consistent with that used by Environment Canada. Using these approaches, PNEC values for BPA range from 11 to 71 μ g/L. Literature studies suggest that application of an additional assessment factor is unwarranted if an SSD-based PNEC is based on chronic data. SSD-derived PNEC values and the traditionally derived PNEC value of 1.6 μ g/L are then compared to concentrations of BPA that have been measured in North American and European surface waters. Adverse risks to aquatic organisms are not anticipated from measured concentrations of BPA in North American and European surface waters.     

The influence of antifouling practices on marine invasions

Vessel hull-fouling is increasingly recognised as one of the major vectors for the transfer of marine non-indigenous species. For hundreds of years, copper (Cu) has been used as a primary biocide to prevent the establishment of fouling assemblages on ships' hulls. Some non-indigenous fouling taxa continue to be transferred via hull-fouling despite the presence of Cu antifouling biocides. In addition, several of these species appear to enjoy a competitive advantage over similar native taxa within metal-polluted environments. This metal tolerance may further assist their establishment and spread in new habitats. This review synthesises existing research on the links between Cu and the invasion of fouling species, and shows that, with respect to the vector of hull-fouling, tolerance to Cu has the potential to play a role in the transfer of non-indigenous fouling organisms. Also highlighted are the future directions for research into this important nexus between industry, ecology and environmental management.     

Improved estimates of environmental copper release rates from antifouling products

The US Navy Dome method for measuring copper release rates from antifouling paint in-service on ships' hulls can be considered to be the most reliable indicator of environmental release rates. In this paper, the relationship between the apparent copper release rate and the environmental release rate is established for a number of antifouling coating types using data from a variety of available laboratory, field and calculation methods. Apart from a modified Dome method using panels, all laboratory, field and calculation methods significantly overestimate the environmental release rate of copper from antifouling coatings. The difference is greatest for self-polishing copolymer antifoulings (SPCs) and smallest for certain erodible/ablative antifoulings, where the ASTM/ISO standard and the CEPE calculation method are seen to typically overestimate environmental release rates by factors of about 10 and 4, respectively. Where ASTM/ISO or CEPE copper release rate data are used for environmental risk assessment or regulatory purposes, it is proposed that the release rate values should be divided by a correction factor to enable more reliable generic environmental risk assessments to be made. Using a conservative approach based on a realistic worst case and accounting for experimental uncertainty in the data that are currently available, proposed default correction factors for use with all paint types are 5.4 for the ASTM/ISO method and 2.9 for the CEPE calculation method. Further work is required to expand this data-set and refine the correction factors through correlation of laboratory measured and calculated copper release rates with the direct in situ environmental release rate for different antifouling paints under a range of environmental conditions.     

Inhibition of acetylcholinesterase by metabolites of copper pyrithione (CuPT) and its possible involvement in vertebral deformity of a CuPT-exposed marine teleostean fish

In a previous study, we demonstrated that exposure to an antifouling biocide, copper pyrithione (CuPT), early during life induced vertebral deformity in the larvae of a marine fish, the mummichog (Fundulus heteroclitus). Skeletal deformities may be caused by inhibition by of acetylcholiensterase (AChE) activity, and to elucidate the mechanism underlying the CuPT-associated vertebral deformity, we first examined whether CuPT, zinc pyrithione (ZnPT), and their degradation products could inhibit AChE activity in the fish. Two of the degradation products, 2,2′-dipyridyldisulfide [(PS)₂] and 2,2′-dithiobispyridine-N-oxide [(PT)₂], but neither CuPT nor ZnPT, exhibited prominent AChE-inhibiting activity. Secondly, thin-layer chromatography revealed that mummichog hepatic microsomes metabolized CuPT to produce (PS)₂ in a microsome-dependent manner. The AChE inhibition induced in CuPT-exposed fish is likely due to (PS)₂ that was produced through metabolism of acquired CuPT. (PS)₂ may cause therefore skeletal deformity in CuPT-exposed fish by means of its neuromuscular blocking properties, through a mechanism similar to that proposed for animals exposed to organophosphorous pesticides.     

Do fish larvae have advantages over adults and other components for assessing estuarine ecological quality?

Using a novel approach to the assessment of ecological quality status of estuarine ecosystems, this study hypothesizes that compared to adult fishes and other components, the younger fish stages will be more sensitive and act as an early warning and will reflect more effectively the ecological status of estuaries. Larval stages of fishes were used to assess the ecological quality status (EQS) of four NW Portuguese estuaries, with different types and magnitudes of human pressures. The larval fish assemblages, together with water column characteristics and pollution indicators (faecal contamination and nutrient load) were sampled in the Lima, Cávado, Ave and Douro estuaries, during spring and autumn 2009. The four estuaries were classified in terms of human pressures by a global pressure index that identified the Cávado estuary as the least impacted estuary, followed by the Ave and Lima, both classified as moderately impacted system, while the Douro was classified as a highly impacted system. The Ave emerged as the most polluted system, carrying the highest nutrient load and sewage contamination. Larval fish assemblages included estuarine species, marine migrants, marine stragglers and the larger estuaries had higher species richness. Compared to adult fishes, three multimetric fish-based indices classified the Cávado, Ave and Douro estuaries with a lower ecological status when fish larvae were used. Similarly, the EQS assessed by macroinvertebrates were equal or higher when compared with fish larvae results. The EQS assessed by fish larvae was negatively correlated with sewage contamination and nitrogen nutrients, but did not reflect other anthropogenic pressures expressed by the global pressure index, which was only detected by adult fish. Fish larvae assessments were able to detect short-time events of hydrological manipulations observed in the Cávado estuary, as well as a seasonal decrease of water quality especially evident in the Ave estuary. The indices used denoted some limitations to the use of fish larvae data, thus emphasising the need for new indices to test the observed tendency for lower EQS given by fish larvae. The advantages and disadvantages of using fish larvae as more sensitive and accurate bioindicators of ecosystem integrity is also discussed as a means of providing strategically important information for improved estuarine management.     

Environmental Impacts of Wild Caught Cod and Farmed Salmon - A Comparison with Chicken (7 pp)

Goal, Scope and Background The objective of this study was to assess environmental impacts of Norwegian cod fishing and salmon farming and compare these with chicken farming in order to find reference levels for environmental performance and identify problem areas and potentials for improvements. Methods A Life Cycle Screening following the production of 0.2 kg fillets as a functional unit through the respective food chains is performed for all 3 products. The analysis is partly quantitative and qualitative focusing on energy use, antifouling and land use impacts. Case studies are performed to investigate potentials for improvements within the fisheries and aquaculture industry. Results and Conclusions It can be concluded that the fishing phase for the cod and the feeding phase for both salmon and chicken dominate for all environmental impacts considered. Chicken is most energy effective followed by salmon and cod, which are almost on the same level. The area of sea floor affected by bottom trawling is around 100 times larger than the land area needed to produce the chicken feed for production of the 0.2 kg fillet. - The case studies show potentials for improvement of environmental performance, both for salmon farming and cod fishing, especially when it comes to energy use. The environmental impacts on the sea floor imposed by bottom trawling are not fully explored, but based on the precautionary principle a reasonable conclusion is that bottom trawls with less impact on the sea floor should be developed. Recommendation and Perspective LCA methods have initially been developed for land based industrial applications. More effort should be given to adapt these to fishing applications in order to obtain more accurate assessment of environmental impacts from seafood products. It is recommended to put more emphasis in finding improved indicators for impacts imposed by over-fishing, fuel emission from combustion at sea, use of antifouling and seafloor ecosystem disturbance.     

Rating species sensitivity throughout gradient systems – a consistent approach for the Baltic Sea

Evaluating the state of benthic communities has played an important role in water quality assessments. Indices incorporating species sensitivities, richness and densities are commonly applied. In Europe, the importance of benthic indices has increased in the last years with the implementation of the European Marine Strategy Framework Directive (MSFD) which at the same time demands the applicability of an index across regional scales. To date, environmental variability is rarely considered in benthic indices and most sensitivity rankings have the disadvantages of static values (i.e. the same value in all areas), expert judgement and a limited geographical range.This study presents species sensitivity values calculated along environmental gradients for the Baltic Sea. Sensitivities were calculated according to the procedure of the Benthic Quality Index (BQI). We created a matrix of subregions, classes of salinity, depth and gear to identify comparable subsets for data analysis. Altogether, 19 subsets were defined within the Baltic Sea basins. Sensitivity values were calculated for 329 species out of a total of 678 species that were recorded in this study. Sensitivity values of taxa vary between subsets as it was expected for different environmental conditions. Most sensitivity values can be assigned to species occurring in euhaline and polyhaline waters. Distribution of species with high and low sensitivity values differed along the salinity gradient. In euhaline waters more species with high sensitivity values occurred than species with low sensitivity values, while in mesohaline waters the ratio of high and low sensitivity values among species was almost equal. In oligohaline waters more species with lower sensitivity values were present.For the first time, sensitivity values were calculated for a large number of species using the same method for the entire Baltic Sea. This results in a Baltic-wide comprehensive set of sensitivity values based on a dataset across subregional borders, and divided along environmental gradients and gear type. The same principles can be applied to transient waters from rivers to coastal lagoons as well as to other environments with gradients of, e.g. hydrodynamic characteristics. Publicly available sensitivity values will increase transparency and support the improvement of state assessments under the MSFD.     

Spectroscopic characterization of extracellular polymeric substances from Escherichia coli and Serratia marcescens: suppression using sub-inhibitory concentrations of bismuth thiols

Free and bound (or capsular) EPS produced by suspended cultures of Escherichia coli and Serratia marcescens were characterized in detail using colorimetric analysis of total proteins and polysaccharides, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and Auger electron spectroscopy (AES) in the presence and absence of bismuth-based antifouling agents. Subtle differences in the chemical composition of free and bound EPS were observed for both bacteria in the absence of bismuth. Total polysaccharides and proteins in free and bound EPS decreased upon treatment with subinhibitory concentrations of lipophilic bismuth thiols (bismuth dimercaptopropanol, BisBAL; bismuth ethanedithiol, BisEDT; and bismuth pyrithione, BisPYR), with BisBAL being most effective. Bismuth thiols also influenced acetylation and carboxylation of polysaccharides in EPS from S. marcescens. Extensive homology between EPS samples in the presence and absence of bismuth was observed with proteins, polysaccharides, and nucleic acids varying predominantly only in the total amount produced. Second derivative analysis of the amide I region of FTIR spectra revealed decreases in protein secondary structures in the presence of bismuth thiols. Hence, antifouling properties of bismuth thiols appear to originate in their ability to suppress O-acetylation and protein secondary structure formation in addition to free and bound EPS secretion.     

Considerations for metabarcoding‐based port biological baseline surveys aimed at marine nonindigenous species monitoring and risk assessments

1. Monitoring introduction and spread of nonindigenous species via maritime transport and performing risk assessments require port biological baseline surveys. Yet, the comprehensiveness of these surveys is often compromised by the large number of habitats present in a port, the seasonal variability, and the time‐consuming morphological approach used for taxonomic identification. Metabarcoding represents a promising alternative for rapid comprehensive port biological baseline surveys, but its application in this context requires further assessments.
2. We applied metabarcoding (based on barcodes of the cytochrome c oxidase subunit I and of the 18S ribosomal RNA gene) to 192 port samples collected (a) from diverse habitats (water column—including environmental DNA and zooplankton, sediment, and fouling structures), (b) at different sites (from inner to outer estuary), and iii) during the four seasons of the year.
3. By comparing the biodiversity metrics derived from each sample group, we show that each sampling method resulted in a distinct community profile and that environmental DNA alone cannot substitute for organismal sampling, and that, although sampling at different seasons and locations resulted in higher observed biodiversity, operational results can be obtained by sampling selected locations and seasons.
4. By assessing the taxonomic composition of the samples, we show that metabarcoding data allowed the detection of previously recorded nonindigenous species as well as to reveal presence of new ones, even if in low abundance.
5. Synthesis and application. Our comprehensive assessment of metabarcoding for port biological baseline surveys sets the basics for cost‐effective, standardized, and comprehensive monitoring of nonindigenous species and for performing risk assessments in ports. This development will contribute to the implementation of the recently entered into force International Convention for the Control and Management of Ships' Ballast Water and Sediments.

     

Neuroendocrine epithelial cells in the broncho-parabronchial transition of embryonic, immature and mature quail (Coturnix coturnix)

The main objective of this integrated light microscopic, transmission and scanning electron microscopic study was to describe in greater detail the structural pattern and developmental stages of pulmonary neuroendocrine epithelial cells (PNECs) in the broncho-parabronchial transition (BPT) of both developing and mature quail. In mature quail the BPT appeared as a diaphragm opening into the parabronchial vestibulum. Perpendicular sections revealed two bilayered crest-like entrance folds invested by a uniform population of granular cells with lamellar bodies and a brush border of blunt microvilli. Solitary PNECs were found interlaced between the granular cells on both sides of the BPT. In addition, PNECs with small dense-cored vesicles (DCVs) were found subepithelially in the lamina propria mucosae of the parabronchial compartment of the BPT, which was surrounded by a capsule of granular cells. Furthermore, clusters of PNECs devoid of any epithelial capsule, but with large DCVs were located in the tunica propria mucosae. The first signs of the developing BPT could be identified as early as embryonic day (ED) 13. By ED 17, the area of the future BPT was seen to be invested by a uniform population of granular cells but the entrance fold proper did not appear until after hatching. Solitary or clustered PNECs were demonstrated in parabronchial buds growing into the mesenchyme on ED 12 and 13: either type I PNECs with small DCVs measuring about 80-120 nm or type II PNECs with large dense granules measuring approximately 150-280 nm. Both types of PNECs represented a temporary cell population in the prehatching period. In the parabronchus no PNECs or neuroendocrine epithelial bodies could be demonstrated in mature and immature quail beyond the BPT.     

Non-toxic antifouling activity of polymeric 3-alkylpyridinium salts from the Mediterranean sponge Reniera sarai (Pulitzer-Finali)

The antifouling activity and toxicity of polymeric 3-alkylpyridinium salts (poly-APS) isolated from the Mediterranean sponge Reniera sarai were studied. The activity of these natural products was compared to that of zinc and copper complexes of pyrithione, two non-persistent booster biocides successfully used in current antifouling coatings. Larvae of Balanus amphitrite (cyprids and nauplii) were used to monitor settlement inhibition and the extent to which inhibition was due to toxicity. The microalga Tetraselmis suecica and larvae of the mussel Mytilus galloprovincialis were used in toxicity bioassays. Compared to the booster biocides, poly-APS were less effective at inhibiting cyprid settlement, but their effects were non toxic and reversible, with very low toxicity against the organisms used in the toxicity bioassays. Although encouraging, these results are not enough to warrant the use of poly-APS as a potential commercial antifoulant. They however justify possible future efforts to chemically synthesize poly-APS analogues for further tests.     

稀有种处理对RDA排序结果影响的比较研究

为了解稀有种对RDA排序结果的影响,该研究以北京东灵山华北落叶松林调查数据为例,在RDA排序的基础上,对比分析了未处理稀有种RDA与剔除频度5%、盖度5%的稀有种后RDA排序结果的差异,并用蒙特-卡罗拟合检验分析了二者物种变量和环境变量之间的相关关系,以及用Spearman秩相关系数检验了对应排序轴的相关性。结果表明:(1)蒙特-卡罗拟合检验结果显示未处理稀有种RDA与剔除稀有种RDA各自对应的物种变量和环境变量之间均呈极显著相关关系;(2)从排序轴特征值对物种数据方差以及物种—环境关系解释量来看,剔除稀有种RDA前两排序轴与前四排序轴均有较高的物种-环境关系累积解释量;(3)剔除稀有种前后对应排序轴的Spearman秩相关分析结果表明,尽管未处理稀有种RDA和剔除稀有种RDA在第三轴和第四轴间存在一定的交叉,但二者对应的前四排序轴均呈极显著的一一对应关系(P0.001),相似性极高。总之,结合物种-环境关系的累积解释量及对应排序轴的相关性可知,在环境因子个数较少、研究尺度较小时,使用RDA排序揭示植物种、植物群落和环境因子之间相互作用的生态关系时,剔除稀有种前后RDA排序具有较高吻合性,只是对环境因子的解释趋势稍有差异。     

Innervation of pulmonary neuroendocrine cells and neuroepithelial bodies in developing rabbit lung.

We investigated the development of innervation of the pulmonary neuroendocrine cell (PNEC) system composed of single cells and organoid cell clusters, neuroepithelial bodies (NEB) in rabbit fetal and neonatal lungs. To visualize the nerve fibers and their contacts with PNECs/NEBs, we used confocal microscopy and multilabel immunohistochemistry (IHC) with pan-neural marker, synaptic vesicle protein 2 (SV2), and serotonin (5-HT) as markers for PNECs/NEBs, and smooth muscle actin or cytokeratin to identify airway landmarks. The numbers and distribution of PNEC/NEB at different stages of lung development (E16, 18, 21, 26, and P2) and the density of innervation were quantified. First PNECs immunoreactive for 5-HT were identified in primitive airway epithelium at E18 as single cells or as small cell clusters with or without early nerve contacts. At E21 a significant increase in the number of PNECs with formation of early innervated NEB corpuscules was observed. The overall numbers of PNECs/NEBs and the density of mucosal, submucosal, and intercorpuscular innervation increased with progressing gestation and peaked postnatally (P2). At term, the majority of NEBs and single PNECs within airway mucosa possessed neural contacts. Such an extensive and complex innervation of the PNEC system indicates a multifunctional role in developing lung and during neonatal adaptation.     

Mismatches between ecosystem services supply and demand in urban areas: A quantitative assessment in five European cities

Assessing mismatches between ecosystem service (ES) supply and demand can provide relevant insights for enhancing human well-being in urban areas. This paper provides a novel methodological approach to assess regulating ES mismatches on the basis of environmental quality standards and policy goals. Environmental quality standards (EQS) indicate the relationship between environmental quality and human well-being. Thus, they can be used as a common minimum threshold value to determine whether the difference between ES supply and demand is problematic for human well-being. The methodological approach includes three main steps: (1) selection of EQS, (2) definition and quantification of ES supply and demand indicators, and (3) identification and assessment of ES mismatches on the basis of EQS considering certain additional criteria. While ES supply indicators estimate the flow of an ES actually used or delivered, ES demand indicators express the amount of regulation needed in relation to the standard. The approach is applied to a case study consisting of five European cities: Barcelona, Berlin, Stockholm, Rotterdam and Salzburg, considering three regulating ES which are relevant in urban areas: air purification, global climate regulation and urban temperature regulation. The results show that levels of ES supply and demand are highly heterogeneous across the five studied cities and across the EQS considered. The assessment shows that ES supply contributes very moderately in relation to the compliance with the EQS in most part of the identified mismatches. Therefore, this research suggests that regulating ES supplied by urban green infrastructure are expected to play only a minor or complementary role to other urban policies intended to abate air pollution and greenhouse gas emissions at the city scale. The approach has revealed to be appropriate for the regulating ES air purification and global climate regulation, for which well-established standards or targets are available at the city level. Yet, its applicability to the ES urban temperature regulation has proved more problematic due to scale and user dependent constraints.     

揭示群落结构及其环境响应的联合物种分布模型的研究进展

物种分布模型通常用于基础生态和应用生态研究,用来确定影响生物分布和物种丰富度的因素,量化物种与非生物条件的关系,预测物种对土地利用和气候变化的反应,并确定潜在的保护区.在传统的物种分布模型中,生物的相互作用很少被纳入,而联合物种分布模型(JSDMs)作为近年提出的一种新的可行方法,可以同时考虑环境因素和生物交互作用,因而成为分析生物群落结构和种间相互作用过程的有力工具.JSDMs以物种分布模型(SDMs)为基础,通常采用广义线性回归模型建立物种对环境变量的多变量响应,以随机效应的形式获取物种间的关联,同时结合隐变量模型(LVMs),并基于Laplace近似和马尔科夫蒙脱卡罗模拟的最大似然估计或贝叶斯方法来估算模型参数.本文对JSDMs的产生及理论基础进行归纳总结,重点介绍了不同类型JSDMs的特点及其在现代生态学中的应用,阐述了JSDMs的应用前景、使用过程中存在的问题及发展方向.随着对环境因素与多物种种间关系研究的深入,JSDMs将是今后物种分布模型研究的重点.