Institute of Hydrobiology, Chinese Academy Of Sciences
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Application of multivariate statistical analysis and water quality index in health risk assessment by domestic use of river water. Case study of Tana River in Kenya
No full textTana River basin covers approximately 21 % of Kenya's total land area. The basin produces about 33.5 % of the country's surface water and 23.8 % of ground water that supports about seven million people. To assess metal and nutrient concentration of Tana River surface water, 57 and 53 water samples were collected in wet (May) and dry (August) seasons of 2018, respectively. Cadmium, chromium, nickel, lead, mercury, arsenic, manganese, zinc, copper, aluminum, boron, selenium, fluoride, chloride, total phosphorus and nitrate were analyzed. Water quality index (WQI) was used to classify water quality into four categories based on pollution level while hazard quotient (HQ) and hazard index (HI) were used to assess non-carcinogenic risk posed to human health since majority of people in the lower reach use Tana River water without any form of treatment. Multivariate statistical analysis was applied to deduce associations and identify pollution sources. Arsenic, cadmium, lead, nickel, selenium and mercury were not detected while manganese, chloride and aluminum were the principal pollutants in the two seasons. 26.3 % of all studied sites recorded HQ> 1 due to high Mn contamination. WQI was noted to be unreliable risk assessment tool since it did not correlate well with HQ and HI besides portraying all sampling sites as bearing suitable water for drinking. Tana River is at risk of eutrophication since total phosphorus concentration detected exceeded recommended threshold. Leached fertilizer from encroached riparian zone, fuel from leaking irrigation pumps and cleaning of motor bikes on water ways was the main source of anthropogenic pollution. Pollution processes and practices observed can be remedied to curb detrimental effects on human health. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved
An OLCI-based algorithm for semi-empirically partitioning absorption coefficient and estimating chlorophyll a concentration in various turbid case-2 waters
No full textAccurate remote assessment of phytoplankton chlorophyll-a (Chla) concentration in turbid case-2 waters is a challenge, owing largely to terrestrial substances (such as minerals and humus) that are optically significant but do not co-vary with phytoplankton. Here, we propose an improved Quasi-Analytical Algorithm (QAA) (denoted as TC2) for retrieving Chla concentrations from remote sensing reflectance (R-rs(lambda)) which can be applied to Sentinel-3 Ocean and Land Colour Instrument (OLCI) images in turbid case-2 waters. TC2 has two main extensions when compared with QAA. First, TC2 makes an additional assumption to separate the total non-water absorption at 665 nm (a(nw)(665)) into phytoplankton absorption (a(ph)(665)) and yellow matter (a(ym)(665)), which is the sum of colored dissolved matter (CDOM) and detritus. Second, for selecting the position of the near-infrared (NIR) band which is used to estimate the signal of total backscattering coefficient (b(b)(lambda(0))) at QAA reference band (lambda(0)), we take into account the assumption that the absorption of pure water should be dominant at this band, as well as the impact of the signal-to-noise ratio (SNR) in the NIR band on the Chla concentration estimating model. When applied to in situ R-rs(lambda) and OLCI match-up R-rs(lambda) data in this study, TC2 provided more accurate Chla estimation than previous Cha concentration retrieval algorithms for turbid case-2 waters. TC2 has the potential for use as a simple and effective algorithm for monitoring Chla concentrations in the turbid case-2 waters at a global scale from space
Integration of taxonomic distinctness indices into the assessment of headwater streams with a high altitude gradient and low species richness along the upper Han River, China
No full textThe multimetric index of biotic integrity (IBI) based on fish assemblages has been widely used to monitor aquatic ecosystem status in headwater streams. However, the application of the IBI has generally been biased by the low number of species and natural altitudinal gradients in these systems. To overcome these limitations, taxonomic distinctness and size-weight-based indices were integrated into our candidate metric pool, and calibration was performed to reduce the effects of the altitudinal gradient on the metrics in our study. Eighty-two sites in six headwater streams along a typical high altitude gradient and with low species richness were sampled. Eighty-three candidate metrics were selected to develop our IBI (IBI-Han) based on the systematic screening method. Six metrics based on taxonomic distinctness, habitat, tolerance guild, reproductive guild and trophic guild were finally retained in the IBI-Han: average taxonomic distinctness, percent rheophilic species, percent tolerant species, percent biomass of water column species, percent lithophilic species, and percent carnivorous species. The IBI-Han performed well in discriminating anthropogenic disturbances not only at training sites but also at testing sites, which suggests that our method could provide a reliable evaluation of the condition of headwater stream ecosystems. Among the six rivers, the Jinshui River showed relatively healthy ecosystem status, while the other five streams were disturbed by various human activities. Our work highlights that taxonomic distinctness indices are robust biomonitoring indices that can be combined with other functional indices to assess high altitude gradient streams in the upper Han River. We believe that the process of developing the IBI-Han could be regarded as a reference for managing headwater streams in other regions of China or in other states
Igf2bp3 maintains maternal RNA stability and ensures early embryo development in zebrafish
No full textEarly embryogenesis relies on maternally inherited mRNAs. Although the mechanism of maternal mRNA degradation during maternal-to-zygotic transition (MZT) has been extensively studied in vertebrates, how the embryos maintain maternal mRNA stability remains unclear. Here, we identify Igf2bp3 as an important regulator of maternal mRNA stability in zebrafish. Depletion of maternal igf2bp3 destabilizes maternal mRNAs prior to MZT and leads to severe developmental defects, including abnormal cytoskeleton organization and cell division. However, the process of oogenesis and the expression levels of maternal mRNAs in unfertilized eggs are normal in maternal igf2bp3 mutants. Gene ontology analysis revealed that these functions are largely mediated by Igf2bp3-bound mRNAs. Indeed, Igf2bp3 depletion destabilizes while its overexpression enhances its targeting maternal mRNAs. Interestingly, igf2bp3 overexpression in wild-type embryos also causes a developmental delay. Altogether, these findings highlight an important function of Igf2bp3 in controlling early zebrafish embryogenesis by binding and regulating the stability of maternal mRNAs.
In early embryogenesis, maternal mRNAs are degraded at the maternal-to-zygotic transition (MZT). Mei et al find that the stability of maternal mRNAs before MZT is maintained by the mRNA binding protein Igf2bp3, which is also required for normal zebrafish development
A novel integrative performance evaluation of constructed wetland on removal of viable bacterial cells and related pathogenic, virulent and multi-drug resistant genes from wastewater systems
No full textIntegrative performance evaluation of constructed wetland in removal different aspects of bacteria under specific local environmental conditions needs to be explored in detail to ensure selection of appropriate and highly efficient macrophytes candidates. To achieve this, integrative purification performance evaluation approach that holistically considers all the aspects of pathogenic bacterial biology (colony numbers, functional gene, species, virulent, pathogenicity and resistant genes) needs to be adopted rather than the commonly known unidimensional approaches that take into account a single bacterial aspect. This study experimentally evaluated the individual performance of three native and one exotic winter tolerant submerged macrophytes combined with a single emergent macrophyte in eradicating faecal related bacterial species and pathotypes across horizontal surface flow constructed wetland. It involved the new multi-dimensional approach that integrated the faecal bacterial colony numbers, functional gene copies, species survival, virulent and pathogenicity as well as antimicrobial resistant in constructed wetland purification evaluation. The results showed Elodea nuttallii and Myriophyllum spicatum as the best candidate partners to Typha latifolia for the highest Purification Efficiency (P < 0.05), of above 97% for removal of faecal bacteria colonies and functional genes, and more than 75% for removal of faecal bacterial strains, pathotypes, virulent and well as resistant genes. However, M. spicatum being a Chinese native species should be much preferred to the invasive E. nuttallii. Therefore, the study recommends the application of local macrophytes such as M. spicatum as the best candidates and the decision should emanate from such a multidimensional/intergrative purification-based evaluation approach.</p
A novel Mg(OH)(2) binding layer-based DGT technique for measuring phosphorus in water and sediment
No full textDiffusive gradients in thin films (DGT) have gained wide attention for in situ measurement of reactive phosphorus species (PO4) in natural water, sediments and potentially soils. In this study, a novel Mg(OH)(2) binding gel was formed using magnesium hydroxide obtained by in situ hydration of calcined magnesium oxide. Laboratory scale experiments showed that the novel Mg(OH)(2) gel had a homogeneous dispersion of fine particles of Mg(OH)(2) with a particle size of 2-5 mu m. With 10 mL of 2.0 mol L-1 NaOH as the eluting agent, the optimal elution efficiency of PO4 on the Mg(OH)(2) gel was 72 +/- 5%. There were linear relationships between the accumulated PO4 mass and the applied PO4 concentration (0.1 to 20 mg P per L), time (0 to 24 h) and temperature (22 to 40 degrees C). The capacity of the Mg(OH)(2) binding layer was determined to be 99.5 mu g P per disc. Tests in synthetic seawater, Chaohu Lake and Yihai Pond confirmed that Mg(OH)(2)-DGT was able to accurately measure phosphorus up to 10 days. This was indicated by the good agreements between the concentrations measured by DGT (C-DGT) technology and by an ex situ chemical method in solution (C-soln), with a C-DGT/C-soln ratio between 0.91 and 1.09
The complete chloroplast genome of Myriophyllum spicatum reveals a 4-kb inversion and new insights regarding plastome evolution in Haloragaceae
No full textMyriophyllum, among the most species-rich genera of aquatic angiosperms with ca. 68 species, is an extensively distributed hydrophyte lineage in the cosmopolitan family Haloragaceae. The chloroplast (cp) genome is useful in the study of genetic evolution, phylogenetic analysis, and molecular dating of controversial taxa. Here, we sequenced and assembled the whole chloroplast genome of Myriophyllum spicatum L. and compared it to other species in the order Saxifragales. The complete chloroplast genome sequence of M. spicatum is 158,858 bp long and displays a quadripartite structure with two inverted repeats (IR) separating the large single copy (LSC) region from the small single copy (SSC) region. Based on sequence identification and the phylogenetic analysis, a 4-kb phylogenetically informative inversion between trnE-trnC in Myriophyllum was determined, and we have placed this inversion on a lineage specific to Myriophyllum and its close relatives. The divergence time estimation suggested that the trnE-trnC inversion possibly occurred between the upper Cretaceous (72.54 MYA) and middle Eocene (47.28 MYA) before the divergence of Myriophyllum from its most recent common ancestor. The unique 4-kb inversion might be caused by an occurrence of nonrandom recombination associated with climate changes around the K-Pg boundary, making it interesting for future evolutionary investigations
Effects of benthivorous fish disturbance and snail herbivory on water quality and two submersed macrophytes
No full textBenthivorous fish disturbance and snail herbivory are two important factors that determine the community structure of submersed macrophytes. We conducted an outdoor mesocosm experiment to examine the separate and combined effects of these two factors on water quality and the growth of two mixed-cultivation submersed macrophytes, Vallisneria natans and Hydrilla verdcillata, with different growth forms. The experiment involved two levels of fish (Misgurnus anguillicaudatus) disturbance crossed with two levels of snail (Radix swinhoei) intensity. The results revealed that fish activity rather than snail activity significantly increased the overlying water concentrations of total suspended solids (TSS), total nitrogen (TN), ammonia nitrogen (N-NH4), total phosphorus (TP) and phosphate phosphorus (P-PO4). However, no differences among treatments were observed for chlorophyll a (chl a) concentrations. Fish disturbance or snail herbivory alone did not affect the relative growth rate (RGR) of H. verticillata, but their combined effects significantly decreased the RGR of H. verticillata. Although snail herbivory alone did not affect the RGR of V. natans, fish disturbance alone and the combined effects of these factors drastically reduced its RGR. Both species exhibited increased free amino acid (FAA) contents and decreased ramet numbers, soluble carbohydrate (SC) contents and starch contents in the presence of the fish. Moreover, compared to H. verticillata, V. natans showed exceedingly low ramet numbers and starch contents in the presence of the fish. H. verticillata had a higher RGR and summed dominance ratio (SDR2) than V. natans in all treatments: H. verticillata also displayed a larger competitive advantage in the presence of fish disturbance. The present study suggests that (1) fish disturbance rather than snail activity increases water nutrient concentrations, (2) low snail density may be harmful to submersed macrophyte growth when the plants are under other abiotic stress conditions and (3) the competitive advantage of H. vertidllata over V. natans is more preponderant in a turbid environment. (C) 2020 Elsevier B.V. All rights reserved
Phytotoxicity, Bioaccumulation, and Degradation of Nonylphenol in Different Microalgal Species without Bacterial Influences
No full textNonylphenol (NP) is a contaminant that has negative impacts on aquatic organisms. To investigate its phytotoxicity, bioaccumulation, and degradation in algae without associated bacteria, six freshwater microalgae-Ankistrodesmus acicularis, Chlorella vulgaris, Chroococcus minutus, Scenedesmus obliquus, Scenedesmus quadricauda, and Selenastrum bibraianum-in bacteria-free cultures were studied. When exposed to 0.5-3.0 mg L-1 NP for 4 days, cell growth and photosynthesis, including maximal photochemistry (Fv/Fm), were suppressed progressively. The antioxidant responses of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) showed species differences. While the antioxidant enzymes in C. vulgaris and S. obliquus were more active with the increase of NP (0-3 mg L-1), they dropped in the other four algae at concentrations of 1 and 1.5 mg L-1. Therefore, C. vulgaris and S. obliquus were designated as NP-tolerant species and showed more conspicuous and faster changes of antioxidant reactions compared with the four NP-sensitive species. All six species degraded NP, but A. acicularis was more reactive at low NP concentrations (<1 mg L-1), suggesting its possible application in sewage treatment for its potential for effective NP removal from water bodies in a suitable scope. Therefore, the conclusion is that biodegradation of NP by algae is species specific
Phylogenetic relationships of three Kudoa spp. with morphologically similar myxospores (K. iwatai, K. lutjanus, and K. bora), with the redescription of K. uncinata and K. petala and description of a new species (K. fujitai n. sp.) in fishes in the South China Sea
No full textMembers of the myxozoan genus Kudoa (Myxosporea: Multivalvulida: Kudoidae) are characterized as having four or more shell valves in a myxospore, with a corresponding number of polar capsules. Certain Kudoa spp. are critical pathogens in fish, causing postmortem myoliquefaction, unmarketable fish musculature due to unsightly macroscopic cysts, and reduced aquaculture production due to the outbreaks of neurological symptoms or cardiac diseases. Molecular genetic techniques have enabled the differentiation of Kudoa spp. with morphologically similar myxospores. In the present study, we employed integrated taxonomic approaches on five Kudoa spp. forming cysts between the trunk muscle myofibers (K. bora from Osteomugil perusii and K. lutjanus from Acanthopagrus latus), or cysts in the gallbladder wall (K. petala from Sillago sihama), and pseudocysts in the trunk muscle myofibers (K. uncinata from Nuchequula nuchalis and K. fujitai n. sp. from O. perusii). These four host fishes, which originated in the South China Sea, were purchased in the wet markets in Zhanjiang City, Guangdong Province, China, between August 2016 and April 2018. We have redescribed the four Kudoa spp. (K. bora, K. lutjanus, K. petala, and K. uncinata) on which little data are available after their original descriptions. Particularly, genetic characterization of K. bora and K. lutjanus, which are known to have myxospores morphologically similar to those of K. iwatai, was performed based on the nuclear ribosomal RNA gene and partial mitochondrial DNA genes such as cytochrome c oxidase subunit I and small and large ribosomal genes, demonstrating the validity and independence of these three kudoid species. We also provide description of a new species-K. fujitai n. sp.-in the present study. Application of integrated taxonomic approaches to known species characterized solely based on morphological criteria, as well as unknown species (e.g., K. fujitai n. sp. in the present study), contributes to better understanding of the biodiversity of Kudoa and multivalvulid myxosporeans