Complex Aquatic Environments Research Articles

Remote sensing of phytoplankton functional types in the coastal ocean from the HyspIRI Preparatory Flight Campaign

The 2013–2015 Hyperspectral Infrared Imager (HyspIRI) Preparatory Flight Campaign, using the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and MODIS/ASTER Airborne Simulator (MASTER), seeks to demonstrate appropriate sensor signal, spatial and spectral resolution, and orbital pass geometry for a global mission to reveal ecological and climatic gradients expressed in the selected California, USA study area. One of the awarded projects focused on the flight transects covering the coastal ocean to demonstrate that the AVIRIS data can be used to infer phytoplankton functional types at the land–sea interface. Specifically, this project directly assesses whether HyspIRI can provide adequate signal in the complex aquatic environment of the coastal zone to address questions of algal bloom dynamics, water quality, transient responses to human disturbance, river runoff, and red tides. Phytoplankton functional type (PFT), or biodiversity, can be determined from ocean color using the Phytoplankton Detection with Optics (PHYDOTax) algorithm and this information can be used to detect and monitor for harmful algal blooms. PHYDOTax is sensitive to spectral shape and accurate retrievals of ocean color across the visible spectral range is needed. The specific goal of this paper is to address the challenges of sensor capabilities and atmospheric correction in coastal environments by assessing two atmospheric correction methods using AVIRIS data for the retrieval of ocean color for use in derived products of chlorophyll-a and phytoplankton functional type. The atmospheric correction algorithms Atmospheric Removal (ATREM) and Tafkaa were applied to AVIRIS imagery of Monterey Bay, CA collected on 10 April 2013 and 31 October 2013. Data products from the imagery were compared with shipboard measurements including chlorophyll-a from whole-water samples and phytoplankton community structure estimated from diagnostic pigment markers using CHEMical TAXonomy (CHEMTAX). Using ATREM and Tafkaa and a selected set of input parameters for the scenes, we were unable to produce accurate retrievals of ocean color for the determination of chlorophyll-a and phytoplankton diversity. A modified ATREM correction produced science-quality data in which chlorophyll-a was accurately estimated using the Ocean Color 3 (OC3) chlorophyll-a algorithm, but biodiversity using PHYDOTax was not accurately estimated. Improvements in sensor calibration, sensitivity, and atmospheric correction of the HyspIRI imagery data set is needed in order to adequately estimate biogeochemically meaningful data products for the ocean such as chlorophyll-a, inherent optical properties, or PFTs. The HyspIRI Science Team is seeking improvements so the HyspIRI Airborne Campaign data set can be used for algorithm development to understand biodiversity and ecosystem function of coastal habitats that are facing increasing threats of human impact and climate change.

Application of the Hyperspectral Imager for the Coastal Ocean to Phytoplankton Ecology Studies in Monterey Bay, CA, USA

As a demonstrator for technologies for the next generation of ocean color sensors, the Hyperspectral Imager for the Coastal Ocean (HICO) provides enhanced spatial and spectral resolution that is required to understand optically complex aquatic environments. In this study we apply HICO, along with satellite remote sensing and in situ observations, to studies of phytoplankton ecology in a dynamic coastal upwelling environment—Monterey Bay, CA, USA. From a spring 2011 study, we examine HICO-detected spatial patterns in phytoplankton optical properties along an environmental gradient defined by upwelling flow patterns and along a temporal gradient of upwelling intensification. From a fall 2011 study, we use HICO’s enhanced spatial and spectral resolution to distinguish a small-scale “red tide” bloom, and we examine bloom expansion and its supporting processes using other remote sensing and in situ data. From a spectacular HICO image of the Monterey Bay region acquired during fall of 2012, we present a suite of algorithm results for characterization of phytoplankton, and we examine the strengths, limitations, and distinctions of each algorithm in the context of the enhanced spatial and spectral resolution.

农田土壤自养微生物的CO2同化功能及同化碳转化的分子生态学机制

PDF HTML阅读 XML下载 导出引用 引用提醒 自养微生物同化CO2的分子生态研究及同化碳在土壤中的转化 DOI: 10.5846/stxb201211051538 作者: 作者单位: 中国科学院亚热带农业生态研究所,湖南农业大学生物科技学院,中国科学院亚热带农业生态研究所,中国科学院亚热带农业生态研究所,中国科学院亚热带农业生态研究所,中国科学院亚热带农业生态研究所,湖南农业大学生物科技学院,中国科学院亚热带农业生态研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目（41271279；41090283）；湖南省自然科学基金资助项目（11JJ4030）；中国科学院青年创新促进会会员资助项目（2012-2015）；中国科学院亚热带农业生态过程重点实验室开放基金资助项目（2010-2012） Molecular mechanism on carbon dioxide assimilation of autotrophic microorganism and carbon translocation in agricultural soils Author: Affiliation: Key Laboratory of Agro-Ecological Processes in Subtropical Region,Institute of Subtropical Agriculture,Chinese Academy of Sciences,College of Bioscience and Biotechnology,Hunan Agricultural University,Key Laboratory of Agro-Ecological Processes in Subtropical Region,Institute of Subtropical Agriculture,Chinese Academy of Sciences,Key Laboratory of Agro-Ecological Processes in Subtropical Region,Institute of Subtropical Agriculture,Chinese Academy of Sciences,Key Laboratory of Agro-Ecological Processes in Subtropical Region,Institute of Subtropical Agriculture,Chinese Academy of Sciences,Key Laboratory of Agro-Ecological Processes in Subtropical Region,Institute of Subtropical Agriculture,Chinese Academy of Sciences,College of Bioscience and Biotechnology,Hunan Agricultural University,Key Laboratory of Agro-Ecological Processes in Subtropical Region,Institute of Subtropical Agriculture,Chinese Academy of Sciences Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:大气中CO2浓度持续升高和全球气候变暖是亟待解决的重大环境问题。自养微生物在环境中广泛分布，能直接参与CO2的同化，因此研究自养微生物同化CO2的分子生态学机制具有重大的科学意义。以往对自养微生物的研究多针对基因组DNA，从DNA水平揭示了不同生态系统中碳同化自养微生物的种群结构和多样性，但这些微生物在生态系统中的具体功能有待进一步的研究。近年来，随着转录组学研究技术和稳定同位素探针技术（SIP）的发展，自养微生物同化CO2的生态机理研究不断深入，这些研究明确揭示了碳同化自养微生物是河流、湖泊和海洋生态系统中CO2固定作用的驱动者，并新发现了一些具有CO2同化功能的微生物群落。基于国内外有关研究进展，从DNA和RNA水平上对自养微生物同化CO2的分子机理以及稳定同位素探针技术（SIP）在碳同化微生物研究中的应用进行了分析 和总结，初步展望了RNA-SIP技术在陆地生态系统碳同化微生物分子生态学研究中的前景。同时，探讨了陆地生态系统同化碳的转化和稳定性机理，以期为深入了解生态系统碳循环过程和应对气候变化提供理论依据。 Abstract:The increase in atmospheric carbon dioxide (CO2) concentration and global climate change are the most important environmental challenges we faced. Autotrophic bacteria, with the capability of CO2 assimilation, are widespread in diverse environments, thus studies on molecular mechanisms of autotrophic bacteria CO2 fixation are of great scientific importance. Previous researches were mainly based on genomic DNA, revealing the diversity and composition of CO2 fixation microorganism in diverse ecological systems. However, the functional implication of these autotrophies is still unknown. Transcriptomics technique and stable isotope probe technique (SIP) are successfully employed in recent studies concerning the ecological function of CO2 fixation microorganism, providing unequivocal evidence for CO2 assimilation by autotrophic microorganisms in complex aquatic environments and identifying new autotrophic bacteria capable of CO2 assimilation. Therefore, the microbial mechanisms of CO2 fixation by autotrophic mciroorganism based on SIP are summarized and the methodological considerations of RNA-SIP for molecular ecology of carbon fixation in agricultural ecosystems are presented. The translocation and stability of assimilated carbon were also discussed. This paper will offer the theoretical basis of terrestrial ecosystem carbon cycle and response to climate change. 参考文献 相似文献 引证文献

Surface Charge Controls the Fate of Au Nanorods in Saline Estuaries

This work reports the distribution of negatively charged, gold core nanoparticles in a model marine estuary as a function of time. A single dose of purified polystyrene sulfonate (PSS)-coated gold nanorods was added to a series of three replicate estuarine mesocosms to emulate an abrupt nanoparticle release event to a tidal creek of a Spartina -dominated estuary. The mesocosms contained several phases that were monitored: seawater, natural sediments, mature cordgrass, juvenile northern quahog clam, mud snails, and grass shrimp. Aqueous nanorod concentrations rose rapidly upon initial dosing and then fell to stable levels over the course of approximately 50 h, after which they remained stable for the remainder of the experiment (41 days total). The concentration of nanorods rose in all other phases during the initial phase of the experiment; however, some organisms demonstrated depuration over extended periods of time (100+ h) before removal from the dosed tanks. Clams and biofilm samples were also removed from the contaminated tanks post-exposure to monitor their depuration in pristine seawater. The highest net uptake of gold (mass normalized) occurred in the biofilm phase during the first 24 h, after which it was stable (to the 95% level of confidence) throughout the remainder of the exposure experiment. The results are compared against a previous study of positively charged nanoparticles of the same size to parameterize the role of surface charge in determining nanoparticle fate in complex aquatic environments.

Assessment of in vivo fluorescence method for chlorophyll-a estimation in optically complex waters (Curuai floodplain, Pará - Brazil)

AIM: This paper describes an experiment carried out to evaluate in vivo fluorescence (IVF) as an alternative method for chlorophyll-a estimation in optically complex aquatic environment (Amazon floodplain lakes) METHODS: The experiment consisted of collecting in situ measurements at 26 sampling stations distributed throughout Curuai floodplain lakes. For each sampling station the following parameters were measured: temperature, turbidity, depth, Secchi depth, chlorophyll-a (Chl-a) concentration, total suspended solids (TSS) and dissolved organic carbon (DOC), concurrently with several transects of IVF. Two methods were tested for quantifying the fluorescence measurement to be used as input for the chlorophyll-a estimates: instantaneous IFV and average IVF. Global and regional models were tested and assessed by analyzing optically active components (Chl-a, DOC and TSS) of the water. RESULTS: Regardless of fluorescence estimating method, the results indicate that it was not possible to fit a global model for estimating Chl-a from IVF for all the lakes in the Curuai floodplain. Regional models provided contrasting results according to the concentration of optically active components. The best results were observed for aquatic systems with a single dominant component homogenously distributed throughout the lake. The results highlight the influence of the ratios Chl-a/TSS, Chl-a/DOC and Phaephytin/Chl-a in the relationship between IVF and chlorophyll concentration. CONCLUSIONS: It was not possible to develop a global model to account for the entire region of Curuai floodplain. The search for regional models provided insights on the main factors affecting the relationship between IVF and Chl-a concentration. Nevertheless this work reinforces the great potential of fluorometry technique, since even with a small number of samples it was possible to set a good model in the main lake of the Curuai floodplain. In spite the fact that this is not an accurate method, it is very useful for assessing the chlorophyll spatial distribution with relatively low cost. These possibilities are very interesting in the execution of field missions in the Amazon region.

Evolution of the brain and sensory organs in Sphenisciformes: new data from the stem penguin Paraptenodytes antarcticus

Penguins have undergone dramatic changes associated with the evolution of underwater flight and subsequent loss of aerial flight, which are manifest and well documented in the musculoskeletal system and integument. Significant modification of neurosensory systems and endocranial spaces may also be expected along this locomotor transition. However, no investigations of the brain and sensory organs of extinct stem lineage Sphenisciformes have been carried out, and few data exist even for extant species of Spheniscidae. In order to explore neuroanatomical evolution in penguins, we generated virtual endocasts for the early Miocene stem penguin Paraptenodytes antarcticus, three extant penguin species (Pygoscelis antarctica, Aptenodytes patagonicus, Spheniscus magellanicus), and two outgroup species (the common loon Gavia immer and the Laysan albatross Phoebastria immutabilis). These endocasts yield new anatomical data and phylogenetically informative characters from the brain, carotid arteries, pneumatic recesses, and semicircular canal system. Despite having undergone over 60 million years of evolution since the loss of flight, penguins retain many attributes traditionally linked to flight. Features associated with visual acuity and proprioception, such as the sagittal eminence and flocculus, show a similar degree of development to those of volant birds in the three extant penguins and Paraptenodytes antarcticus. These features, although clearly not flight-related in penguins, are consistent with the neurological demands associated with rapid manoeuvring in complex aquatic environments. Semicircular canal orientation in penguins is similar to volant birds. Interestingly, canal radius is grossly enlarged in the fossil taxon Pa. antarcticus compared to living penguins and outgroups. In contrast to all other living birds, the contralateral anterior tympanic recesses of extant penguins do not communicate. An interaural pathway connecting these recesses is retained in Pa. antarcticus, suggesting that stem penguins may still have employed this connection, potentially to enhance directional localization of sound. Paedomorphosis, already identified as a potential factor in crown clade penguin skeletal morphology, may also be implicated in the failure of an interaural pathway to form during ontogeny in extant penguins.

The structure and origin of dissolved organic matter studied by UV-vis spectroscopy and fluorescence spectroscopy in lake in arid and semi-arid region

To develop a proper indicator which could predict water quality and trace pollution sources is critically important for the management of sustainable aquatic ecosystem. In our study, seven water samples collected from Wuliangsuhai Lake in Inner Mongolia were used. UV-visible spectra and synchronous fluorescence spectra were applied to investigate the humification degree and aromatic structure of dissolved organic matter (DOM) extracted from water samples. The results showed that both samples from W1 site and W3 site display lower humification degree and less aromatic structure, where industrial wastewater and domestic sewage, and reclaimed water of farmland irrigation, were accepted respectively. After computing the values of SUVA254, A280, A250/365, A253/203 and A226–400, we reached the conclusion that they have a consistent trend (W4> W6> W5> W2> W7> W1> W3). Fluorescence index (f450/500) was always utilised to interpret the origin of organic matter in a complex aquatic environment system. Values of f450/500 are closer to 1.60, indicating that humic substances derived from terrestrial sources and biological sources. Our study demonstrated that reclaimed water of farmland irrigation, industrial wastewater and domestic sewage will definitely influence the humification degree and amount of the aromatic structure of DOM.

The use of polycyclic aromatic hydrocarbons as a particulate tracer in the water column of Gaoping (Kaoping) Submarine Canyon

Time-series samples of settling particles were collected in the water column of Gaoping (formerly spelled Kaoping) Submarine Canyon (KPSC) with two sediment traps on taut-line moorings deployed at two different depths (60 and 280 m) between May 26 and June 27, 2004. Average total polycyclic aromatic hydrocarbon (PAH) concentrations of upper and lower trap array samples were 310 ± 61 ng g − 1 dw (range: 200–440) and 240 ± 36 ng g − 1 dw (range: 180–290), respectively. Principal component analysis results suggest that PAH sources in the trap-collected particles included diesel vehicle/coal burning, diagenetic sources, and petroleum release. PAH downward fluxes based on settling particles were estimated to be 12–44 μg m − 2 d − 1 . These values are higher than those reported in the literature for most coastal areas. During the sampling period, both traps were significantly tilted by tidal current and fluctuated vertically. The upper traps experienced greater vertical movements, thus their particle characteristics (e.g., POC, particle mass, and fine particle fraction) varied more than those of the lower traps. Hourly depth variations of the tilted sediment trap array were echoed by the corresponding total PAH concentrations. Moreover, the PAH composition of the collected particles was related to the flow direction and speed. These observations suggest that PAHs can be used as an effective chemical tracer for the transport of terrestrial and marine particulates in a complex aquatic environment like Gaoping (Kaoping) Submarine Canyon.

Detection of Virulence Genes in Vibrio cholerae Isolated from Aquatic Environment in Kerala, Southern India

Vibrio cholerae is the etiologic agent of cholera. It is an autochthonous inhabitant of all aquatic environments. The virulence of V. cholerae is maintained by the CTX genetic element and tcpA gene. In the present investigation, environmental strains of V. cholerae isolated from different aquatic biotopes in Kerala were identified and serotyped. The antibiotic resistance pattern and presence of virulence and regulatory genes were examined. We found the presence of toxigenic non-O1/non-O139 strains harboring the CTX genetic element, heat-stable enterotoxin, rtxA gene, El Tor hemolysin, and Vibrio pathogenicity island (VPI). The strains also produced the cholera toxin (CT) as determined by monosialoganglioside enzyme-linked immunosorbent assay. A few strains belonging to the O1 serogroup but lacking the CTX genetic element were also observed. The majority of the environmental strains belonged to non-O1/non-O139 serogroup with many possessing toxR, ompU, heat-stable enterotoxin, and rtxA gene. The toxigenic non-O1/non-O139 strains exhibited resistance to trimethoprim, ampicillin, and polymixin B and intermediate resistance to co-trimoxazole. However, all other environmental strains were found resistant to ampicillin and polymixin B. Our findings demonstrate that the virulence genes are dispersed among the environmental strains of V. cholerae and a complex aquatic environment can give rise to pathogenic V. cholerae.

Water Quality in Mangueira Bay: Anthropic and Natural Contamination

Mangueira Bay is located south of Patos Lagoon. It receives poorly treated official and clandestine household and industrial effluents from the city of Rio Grande. This study analyzes parameters that characterize the water quality of Mangueira Bay at various sites influenced by effluent discharge from different activities carried out in the surrounding area. These data are also useful for water-quality models. Water was sampled under various salinity conditions in October 2002 (spring), June 2003 (winter), December 2003 (summer) and April 2004 (fall). Because sewage discharge is relatively constant, water contamination is highly dependent on the association between industrial activity and hydrodynamics. The simultaneous combination of nitrogenous and phosphatic nutrient inputs causes serious eutrophication problems and an excessive increase in vegetal biomass in Mangueira Bay. An assessment of bacteria, greases and oils indicates that the water contamination near the city of Rio Grande comes not only from domestic sources but also from wastewater from fish plants and a local petroleum refinery. In order for Mangueira Bay to meet the requirements based on its water classification under federal law and enforced by environmental agencies, the discharge of clandestine domestic and industrial effluents with no or insufficient treatment must be avoided because the survival of artisanal fishing and natural species depends on the proper preservation of this complex aquatic environment.

Incompatibility of sulphate compounds and soluble bicarbonate salts in the Rio Cruces: reply to Harding et al. (2007)

Regarding the fate of Egeria densa in the Rio Cruces estuary, we consider that no new data has been put forward by Harding et al. (2007, available at: www.int-res.com/articles/esep/2007/E72.pdf) on the real issue of the Ramsar site, Carlos Andwandter Sanctuary, its collapse. However, we answer the criticisms raised by Harding et al. (2007) below. The major contribution to the issue by Harding et al. (2007) is their statement: ‘This does not preclude the possibility that effluent from the CELCO pulp mill may have caused adverse effects in the sanctuary.’ Harding et al. (2007) propose that potassium may have caused the effect observed in the microcosm experiments of Mulsow & Grandjean (2006). This possibility will be tested and published in due course under similar but more precise measurements of the photorespiration of Egeria densa if funds are available. The arguments of Harding et al. (2007) with respect to the field data of Mulsow & Grandjean (2006) neglect the fact that we are working in a complex aquatic environment, in which residence time and hydraulic and tidal regimes dominate the scenario where all the reactions take place. Mulsow & Grandjean (2006) mentioned that pH and temperature are also major contributors to anion–cation exchange conditions and dominance of CO2 or HCO3 in the water. Harding et al. (2007) fail to comment on the historical evidence of change in HCO3 at Rucaco station (DGA [1993], Station Code 10134800-8). Before the pulp mill began producing cellulose, Rucaco station, approximately 1 km downstream from the pulp mill, had 0.6 mg l–1 of sulphate, compared to present values of more than 4 mg l–1. We insist that this is not a coincidence: this is not a river, it is a sanctuary located in an estuary; this is not distilled water chemistry, a deep water body, or a simple ecosystem. If the discharge water is as clean as the pulp mill says it is, then why don’t they discharge it upstream of the water intake supplying the cellulose plant? This would decrease the impact, if any, to a minimum, with no need to discharge to the nearby sea.

Aquatic invertebrate responses to fish presence and vegetation complexity in Western Boreal wetlands, with implications for Waterbird productivity

Aquatic invertebrates are essential to wetland function, serving as the key trophic link between primary producers, fish, and waterfowl in boreal wetlands. We studied how both aquatic vegetation complexity and prevalence, and fish presence, could be used to predict the distribution of invertebrate biomass in 24 wetlands of the Western Boreal Forest (WBF). The percent volume occupied by aquatic plants was significantly positively associated with overall invertebrate biomass per liter (P = 0.009). Particular invertebrate functional feeding groups were correlated with types of aquatic macrophyte architecture; herbivorous invertebrate biomass (mg/L) was greater in more complex aquatic environments, and predatory invertebrate biomass was greater in environments with simple plant architecture. Wetlands inhabited by Brook Stickleback (Culaea inconstans) had reduced invertebrate biomass of the predatory, non-predatory (excluding omnivores), and gatherer/collector functional feeding groups. Gatherer/collector, predator, shredder, and piercer invertebrate groups were negatively correlated with dissected leaved plant dominance in those wetlands without fish. These invertebrate groups comprise the bulk of invertebrate protein available to nesting hen mallards and their ducklings. We suggest that the presence of stickleback and/or dominance of dissected leaved plants in the wetlands of the WBF results in decreased food supply for hatchling waterfowl.

Potential impacts of water injection dredging on water quality and ecotoxicity in Limehouse Basin, River Thames, SE England, UK

The use of water injection dredging (WID) is increasing in the UK’s inland waterways and marinas. Jets of water are injected under low pressure directly into bottom sediment creating a turbulent water-sediment mixture that flows under the influence of gravity. Many of these sediments are highly contaminated and little is known of the effects of contaminant release on water quality or the risk to biota living in both the sediment and the water column. Sediment cores were collected from Limehouse Basin, a proposed WID site in SE England and current sediment toxicity was assessed using a number of techniques. Comparison of metal data to US sediment quality guidelines indicated intermediate levels of toxicity while, calculation of acid volatile sulphide to simultaneously extracted metal ratios underestimated the potential toxicity to sediment dwelling organisms. In contrast, porewater ammonia concentrations were in excess of all published ecotoxicological guidelines and indicate serious risk to biota. Re-suspension experiments were used to mimic the effects of WID on overlying water quality and ecotoxicity tests were carried out on elutriates using Daphnia magna to examine the impacts on biota. Concentrations of a range of metals in the elutriates predict that adverse biological effects would be observed during WID, however only 10% of the elutriate samples caused an adverse effect on Daphnia. Limehouse Basin is a complex aquatic environment receiving predominantly fresh waters while the sediments have high porewater chloride concentrations reminiscent of previous tidal inputs to the basin, making the choice of test organism problematic.

Hydrodynamic stability of swimming in ostraciid fishes: role of the carapace in the smooth trunkfish Lactophrys triqueter (Teleostei: Ostraciidae).

The hydrodynamic bases for the stability of locomotory motions in fishes are poorly understood, even for those fishes, such as the rigid-bodied smooth trunkfish Lactophrys triqueter, that exhibit unusually small amplitude recoil movements during rectilinear swimming. We have studied the role played by the bony carapace of the smooth trunkfish in generating trimming forces that self-correct for instabilities. The flow patterns, forces and moments on and around anatomically exact, smooth trunkfish models positioned at both pitching and yawing angles of attack were investigated using three methods: digital particle image velocimetry (DPIV), pressure distribution measurements, and force balance measurements. Models positioned at various pitching angles of attack within a flow tunnel produced well-developed counter-rotating vortices along the ventro-lateral keels. The vortices developed first at the anterior edges of the ventro-lateral keels, grew posteriorly along the carapace, and reached maximum circulation at the posterior edge of the carapace. The vortical flow increased in strength as pitching angles of attack deviated from 0 degrees, and was located above the keels at positive angles of attack and below them at negative angles of attack. Variation of yawing angles of attack resulted in prominent dorsal and ventral vortices developing at far-field locations of the carapace; far-field vortices intensified posteriorly and as angles of attack deviated from 0 degrees. Pressure distribution results were consistent with the DPIV findings, with areas of low pressure correlating well with regions of attached, concentrated vorticity. Lift coefficients of boxfish models were similar to lift coefficients of delta wings, devices that also generate lift through vortex generation. Furthermore, nose-down and nose-up pitching moments about the center of mass were detected at positive and negative pitching angles of attack, respectively. The three complementary experimental approaches all indicate that the carapace of the smooth trunkfish effectively generates self-correcting forces for pitching and yawing motions--a characteristic that is advantageous for the highly variable velocity fields experienced by trunkfish in their complex aquatic environment. All important morphological features of the carapace contribute to producing the hydrodynamic stability of swimming trajectories in this species.

Phytochelatin production in freshwater algae Stigeoclonium in response to heavy metals contained in mining water; effects of some environmental factors

Production of phytochelatins (PC) in two freshwater, filamentous green algae of the genus Stigeoclonium, in response to heavy metals contained in mining water was studied. Stigeoclonium sp. grown abundantly in ditches with the mining water (southern Poland) accumulated high amounts of heavy metals. The other studied alga Stigeoclonium tenue Kütz. was isolated from unpolluted lake water in the Netherlands. Both algae exposed to the heavy metal mixture (17 μM; mainly zinc) contained in the hard, alkaline (pH 8.2) mining water produced similar amounts of phytochelatins (PC 2 and PC 3): 500–600 nmol SH g −1 dry weight. After water acidification to pH 6.8, a >2-fold increase of the total phytochelatin level as well as the appearance of longer chain peptide PC 4 in the cells of both algae was observed. The concentration of labile forms of zinc in the acidified mining water was four times as high as that in the alkaline water. The heavy metal mixture (17 μM) in non-complexing solution of pH 6.8 caused a comparable phytochelatin production in both Stigeoclonium strains as the same mixture present in the acidified mining water. However, in the non-complexing solution of pH 8.2, the metal mixture induced in algae more PCs than at pH 6.8. A positive effect of bicarbonate enrichment in the solution on the PC production in S. tenue was also observed. Stigeoclonium sp. exposed to high concentrations (10 μM) of individual metals (Zn, Pb and Cd available as free cations) synthesised much higher amounts of phytochelatins (PC 2–PC 4) than in response to the metal mixture contained in the mining water. The order of PC induction by the studied metals in the Stigeoclonium sp. was Cd>Pb>Zn. Addition of suspended solid matter to the heavy metal solution resulted in essential quantitative changes in phytochelatins in algal cells; a considerable decrease of PC 2, PC 3 and PC 4 levels was observed. The PC production in algae of the genus Stigeoclonium exposed to the heavy metal mixture is discussed in the context of various metal bioavailability and the algal adaptation to complex aquatic environment.

Pollution Remediation Planning In Developing Countries

Increasing water scarcity in many developing countries is forcing investments into remediation of water quality at the basin or sub-basin scale in order to increase water availability. Remediation decisions involving complex aquatic environments are often made in data-poor and knowledge-poor situations. Remediation objectives are often poorly articulated, raise unrealistic expectations, and cannot be evaluated in cost-benefit terms. Mathematical modelling, as a means of determining remediation options, is the usual method of choice in data-rich developed countries and requires substantial investment in reliable data, scientific capacity and a sophisticated management culture that generally are not found in developing countries. Modelling is expensive, has numerous other technical problems in developing countries, requires a high degree of input by foreign experts, and rarely leaves residual capacity in the developing country. In contrast, new techniques in knowledge-based (K-B) prediction focus on use of local and domain knowledge to establish meaningful program objectives. K-B-based decision support systems (DSS) allow the client to game with alternative remediation options with outputs expressed in degree of uncertainty in the assumptions and analytical processes included in the DSS system. The K-B approach builds local capacity and, by providing access to domain knowledge, reliance on foreign experts diminishes as local experts assume similar tasks elsewhere in the country.

Chlorophyll and carotenoid pigments in solar saltern microbial mats

The distributions of carotenoids, chlorophylls, and their degradation products have been studied in two microbial mat systems developed in the calcite and calcite/gypsum evaporite domains of a solar saltern system. Phormidium valderianum and Microcoleus chthonoplastes are the dominant cyanobacterial species, respectively, and large amounts of Chloroflexus-like bacteria occur in the carbonate/gypsum mat. In both systems, the major pigments are chlorophyll a, zeaxanthin, β-carotene and myxoxanthophyll, which originate from these mat-building cyanobacteria. This common feature contrasts with differences in other pigments that are specific for each mat community. Thus, chlorophyll c and fucoxanthin, reflecting diatom inputs, are only found in the calcite mat, whereas the calcite/gypsum mat contains high concentrations of bacteriochlorophylls c produced by the multicellular green filamentous bacteria. In both cases, the depth concentration profiles (0–30 and 0–40 mm) show a relatively good preservation of the cyanobacterial carotenoids, zeaxanthin, β-carotene, myxoxanthophyll, and echinenone. This contrasts with the extensive biodegradation of cyanobacterial remains observed microscopically. Fucoxanthin in the calcite mat is also transformed at a faster rate than the cyanobacterial carotenoids. Chlorophyll a, the major pigment in both mats, exhibits different transformation pathways. In the calcite/gypsum mat, it is transformed via C-13 2 carbomethoxy defunctionalization prior to loss of the phytyl chain, leading to the formation of pyrophaeophytin a and, subsequently, pyrophaeophorbide a. On the other hand, the occurrence of the enzyme chlorophyllase, attributed to diatoms in the calcite mat, gives rise to extensive phytyl hydrolysis, with the formation of chlorophyllide a, pyrophaeophorbide a and, in minor proportion, phaeophorbide a. Studies of the sources of the photosynthetic pigments and of their transformation pathways in such simplified ecosystems provide a basis for the understanding of the distribution patterns of these compounds in more complex aquatic environments.

Effects of Egg Size on Success of Larval Salamanders in Complex Aquatic Environments

Effects of egg size on growth, survival, and metamorphosis of larval salamanders (Ambystoma talpoideum) were examined in varying environments. Pond drying regime and presence vs. absence and an interspecific competitor were manipulated in factorial experimental using artificial ponds to measure the responses of larvae. Females that were 4 yr old produced larger eggs and hatchlings than 1—yr—old females. Differences in body size at hatching persisted through day 49 of the experiment but disappeared by day 129. Drying regime also affected body size at day 49 but not at day 129. Larvae from large eggs, and larvae in constant water level ponds, had higher survival to day 129 than larvae from small eggs, and in drying ponds. There was also a significant interaction between egg size and drying regime. Larvae from large eggs survived better than larvae from small eggs in the constant water level ponds, but not in drying ponds. Interspecific competitors did not affect growth or survival to day 129. More individuals metamorphosed from drying ponds than from constant water level ponds. The growth advantages conferred by larger body size at hatching are transient and may disappear during compensatory growth later in the larval period. Body size advantages early in the larval period, however, probably account for increased survival through size—specific mechanisms at a time when newly hatched larvae are most vulnerable.