Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 444
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Mar Pollut Bull ; 145: 105-117, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31590766

RESUMO

The Beagle Channel is a remote subantarctic environment where mussel aquaculture initiatives have existed since the early 1990s. Here we analyze phytoplankton biomass and composition, and the occurrence of harmful microalgae species and their toxins at three sites during the period 2015-2016. The occurrence of potentially harmful algae was observed throughout the study period, including toxigenic dinoflagellates such as Alexandrium catenella (Group I of the A. tamarense complex), A. ostenfeldii, Dinophysis acuminata, Gonyaulax spinifera, Azadinium sp., and the diatoms Pseudo-nitzschia australis and P. fraudulenta. Toxic dinoflagellates were detected in low densities whereas a Pseudo-nitzschia bloom was observed in late February. Isolates of A. catenella and P. delicatissima sensu stricto were phylogenetically characterized. The toxin profile of A. catenella was dominated by GTX4, while P. delicatissima sensu stricto showed no production of the neurotoxin domoic acid in culture conditions. The results provide base-line information for the management of harmful algal blooms in this little explored subantarctic area.


Assuntos
Aquicultura , Diatomáceas/química , Dinoflagelados/química , Toxinas Marinhas/análise , Fitoplâncton/química , Animais , Biomassa , Diatomáceas/classificação , Diatomáceas/crescimento & desenvolvimento , Dinoflagelados/classificação , Dinoflagelados/crescimento & desenvolvimento , Proliferação Nociva de Algas , Microalgas/química , Microalgas/classificação , Microalgas/crescimento & desenvolvimento , Fitoplâncton/classificação , Fitoplâncton/crescimento & desenvolvimento , América do Sul
2.
Chemosphere ; 237: 124430, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31369904

RESUMO

Coastal environment are often stress from petroleum-derived hydrocarbon pollution. However, petroleum-derived hydrocarbon is persistent organic pollutants and their biodegradation by phytoplankton is little known. Five species of marine phytoplankton, including Dunaliella salina, Chlorella sp., Conticribra weissflogii, Phaeodactylum tricornutum Bohlin, and Prorocentrum donghaiense, have been used to test their tolerance to petroleum hydrocarbon contamination. D.salina and Chlorella sp can survive in high levels of No. 0 diesel oils water-soluble fractions (WSFs, 5.0 mg L-1), furthermore, petroleum hydrocarbon could be biodegraded effectively by them (Fig. 2). The content of ß-carotene in these two species of phytoplankton has significant correlation with degradation rate of WSFs concentrations (Fig. 4), petroleum hydrocarbons could be biodegraded effectively by algae. Meanwhile, the ·OH in seawater can be removed by ß-carotene effectively so that algal cells could be protected by the ß-carotene for its strong antioxidant capacity. Therefore, ß-carotene as a coin has two sides on the degradation of WSFs. Here we explore the relationship between plankton-based ß-carotene and biodegradable adaptabllity to petroleum-derived hydrocarbon, which offers a green technology for petroleum-derived hydrocarbon treatment.


Assuntos
Biodegradação Ambiental , Hidrocarbonetos/metabolismo , Fitoplâncton/química , beta Caroteno/análise , Petróleo , Poluição por Petróleo/prevenção & controle , Plâncton/química , Plâncton/metabolismo , Água do Mar/química , Solubilidade
3.
Ecol Lett ; 22(9): 1462-1471, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31270952

RESUMO

In subtropical oceans phytoplankton carbon: phosphorus (C : P) ratios are high, and these ratios are predicted to increase further with rising ocean temperatures and stratification. Prey stoichiometry may pose a problem for copepod zooplankton nauplii, which have high phosphorus demands due to rapid growth. We hypothesised that nauplii meet this demand by consuming bacteria. Naupliar bacterial and phytoplankton carbon and phosphorus ingestion, assimilation and incorporation were traced using 33 P and 14 C radioisotopes. Bacterial carbon was incorporated four times less efficiently into biomass than phytoplankton carbon. In contrast, bacterial and phytoplankton phosphorus were incorporated at similar efficiencies, and bacteria could meet a substantial amount of naupliar phosphorus requirements. As parts of the ocean become more oligotrophic, bacteria could help sustain naupliar growth and survival under suboptimal stoichiometric conditions. Thus, nauplii may be a shortcut for phosphorus from the microbial loop to the classical food web.


Assuntos
Bactérias/química , Copépodes/metabolismo , Cadeia Alimentar , Fósforo/metabolismo , Animais , Carbono/metabolismo , Radioisótopos de Carbono/análise , Oceanos e Mares , Radioisótopos de Fósforo/análise , Fitoplâncton/química
4.
Isotopes Environ Health Stud ; 55(4): 366-384, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31185743

RESUMO

Benthic invertebrates are a crucial trophic link in Arctic marine food webs. However, estimates of the contribution of different primary production sources sustaining these organisms are not well characterised. We measured the stable carbon isotope values (δ13C) of essential amino acids (EAAs) in muscle tissue from two common bivalve genera (Macoma spp. and Astarte spp.) collected in Hanna Shoal in the northeastern Chukchi Sea. Mixing models comparing the δ13CEAA fingerprints of the bivalves to a suite of primary production endmembers revealed relatively high contributions of EAAs from phytoplankton and bacteria in both species. We also examined whether δ13CEAA fingerprints could be produced from the EAAs preserved in bivalve shells, which could allow primary production sources to be estimated from ancient bivalve shells. The δ13CEAA fingerprints from a suite of paired modern bivalve shells and muscle from Macoma calcarea from across the Chukchi Sea revealed a correspondence between the estimates of the dominant primary production source of EAAs derived from analyses of these two tissue types. Our findings indicate that δ13CEAA fingerprinting of marine bivalves can be used to examine dominant organic matter sources in the Arctic marine benthos in recent years as well as in deeper time.


Assuntos
Aminoácidos Essenciais/metabolismo , Bivalves/metabolismo , Isótopos de Carbono/análise , Cadeia Alimentar , Aminoácidos Essenciais/química , Exoesqueleto/química , Animais , Regiões Árticas , Bivalves/química , Monitoramento Ambiental/métodos , Modelos Biológicos , Músculos/química , Músculos/metabolismo , Fitoplâncton/química , Fitoplâncton/metabolismo , Alga Marinha/química , Alga Marinha/metabolismo
5.
Environ Sci Pollut Res Int ; 26(20): 20428-20438, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31102221

RESUMO

The content of trace metals (Pb, Zn, Cd, Cu) was examined in water-in the suspended and dissolved forms, in the suspended material and organisms of the food chain-phytoplankton-filter-feeding bivalves (Kunashiria coptzevi, Corbicula japonica) in fresh- and brackish-water lakes of the coast of the Sea of Japan. It was demonstrated that the fresh-water lakes were no different from the brackish-water ones in concentrations of metals in organisms and water. The anthropogenically altered Vaskovskoye Lake is distinguished among the fresh lakes by the elevated concentrations of Pb and Zn in the ecosystem components. Trace metals do not accumulate in the phytoplankton-mollusks food chain: content of Pb decreases while concentrations of Zn, Cd, and Cu do not change practically. This is associated with the low content of heavy metals in water, suspended matter, and suspended organic carbon controlling the filtration rate of organisms.


Assuntos
Bivalves/química , Metais/análise , Fitoplâncton/química , Poluentes Químicos da Água/análise , Animais , Organismos Aquáticos , Bivalves/metabolismo , Monitoramento Ambiental/métodos , Cadeia Alimentar , Água Doce , Sedimentos Geológicos/análise , Lagos , Metais/farmacocinética , Federação Russa , Oligoelementos/análise , Poluentes Químicos da Água/farmacocinética
6.
Environ Sci Pollut Res Int ; 26(17): 17512-17519, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31025277

RESUMO

Phytoplankton assemblages were investigated in 2015 along the seasonal changes of the Genhe River in the Greater Hinggan Mountains. The survey was performed in June (spring), August (summer), and October (autumn) at nine sampling stations to study the community composition, abundance, and biodiversity. The results showed that 61 species belonging to 16 genera were identified, including Bacillariophyta of 31 species, Dinophyta 2 species, Cyanophyta 2 species, Chlorophyta 20 species, Chrysophyta 2 species, and Cryptophyta 1 species; Besides, Bacillariophyta are dominant species. Shannon-Wiener (H') and Pielou (J') indices indicated that phytoplankton community was stable. And these two indices were significantly lower in summer than in spring and autumn. Phytoplankton abundance and biomass show significant differences in each season. The total phytoplankton abundance (1122.3 × 104 ind/L) and biomass (6.5709 mg/L) in summer are much higher than that in spring and autumn. There were few species and low abundance and biomass in the upper reaches of Genhe River; this fact can be explained by the cold climate in the Greater Higgnan Mountains region. Canonical correspondence analysis (CCA) was used to analyze the data. It revealed that Fe3+, Cu2+, pH, and water temperature (WT) were responsible for most of the variation in space in the phytoplankton community. These environmental parameters play an essential role in the community structure variation of phytoplankton in the upper reaches of Genhe River, the strong association between phytoplankton community structure and ecological factors is varied in each season.


Assuntos
Clorófitas/química , Cianobactérias/química , Diatomáceas/classificação , Dinoflagelados/química , Fitoplâncton/classificação , Rios/química , Biodiversidade , Biomassa , China , Diatomáceas/química , Ecologia , Fitoplâncton/química , Estações do Ano , Temperatura Ambiente , Qualidade da Água
7.
Mar Pollut Bull ; 141: 462-471, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30955757

RESUMO

Ocean acidification (OA) has potential to affect marine phytoplankton in ways that are partly understood, but there is less knowledge about how it may alter the coupling to secondary producers. We investigated the effects of OA on phytoplankton primary production, and its trophic transfer to zooplankton in a subtropical eutrophic water (Wuyuan Bay, China) under present day (400 µatm) and projected end-of-century (1000 µatm) pCO2 levels. Net primary production was unaffected, although OA did lead to small decreases in growth rates. OA had no measurable effect on micro-/mesozooplankton grazing rates. Elevated pCO2 had no effect on phytoplankton fatty acid (FA) concentrations during exponential phase, but saturated FAs increased relative to the control during declining phase. FA profiles of mesozooplankton were unaffected. Our findings show that short-term exposure of plankton communities in eutrophic subtropical waters to projected end-of-century OA conditions has little effect on primary productivity and trophic linkage to mesozooplankton.


Assuntos
Monitoramento Ambiental/métodos , Fitoplâncton/crescimento & desenvolvimento , Água do Mar/química , Zooplâncton/crescimento & desenvolvimento , Animais , Ciclo do Carbono , Dióxido de Carbono/análise , China , Eutrofização , Ácidos Graxos/análise , Concentração de Íons de Hidrogênio , Oceanos e Mares , Fitoplâncton/química , Zooplâncton/química
8.
ScientificWorldJournal ; 2019: 8456371, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30992695

RESUMO

The importance of phytoplankton is high in transformation of substances in aquatic ecosystems and in formation of suspension's material structure. Its main functions are consumption of the dissolved biogenic components and chemical elements and their conversion to a firm phase. The article is devoted to the bioaccumulation of microelements by phytoplankton in the ecosystem of the Azov Sea. The fact that the algal biomass during the periods of blooming in the sea reaches 1,400 g/l makes this study especially urgent. The authors define the rates of biogeochemical cycle and the intensity of chemical elements' consumption and also investigate the role of phytoplankton in the formation chemical peculiarities of bottom deposits and its involvement in sedimentogenesis in the Azov Sea. The cause of the reduced trace element content in bottom deposits relatively to suspended material is established. It is noted that the amount of some elements annually consumed by algae of the Azov Sea is up to 75% from their maximum delivery by terrigenous material.


Assuntos
Fitoplâncton/fisiologia , Ecossistema , Metais/metabolismo , Oceanos e Mares , Fitoplâncton/química , Fitoplâncton/metabolismo , Federação Russa , Espectrofotometria Atômica
9.
Environ Sci Pollut Res Int ; 26(13): 12881-12893, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30887454

RESUMO

Camorim is a small, eutrophic reservoir in Rio de Janeiro, Brazil, with a phytoplankton community dominated most of the year by the filamentous diatom Aulacoseira spp. and the toxic cyanobacterium Cylindrospermopsis raciborskii. As filamentous species can be a poor food for grazers, we hypothesize that phytoplankton from this reservoir would constrain cladoceran fitness due to nutritional limitation and/or toxicity when animals fed mixtures of cultured green algae and natural seston. Clones of different cladoceran species were exposed either to seston from Camorim reservoir sampled in different seasons or to a C. raciborskii strain (CYLCAM-2) isolated from the reservoir. In short-term assays, cladocerans were exposed to either 100% seston or mixtures of 50% seston added to green algae (200 µg C L-1), and their survivorship and somatic growth were measured for 4 days. In life table assays, neonates were exposed to the same seston treatments over 14 days and age at first reproduction, survivorship, fecundity, total offspring, and the intrinsic rate of natural increase (r) were assessed. In general, seston negatively affected cladoceran survivorship and fitness (r), but this response was seasonally and species specific. Stronger effects of CYLCAM-2 than those caused by seston on survivorship, somatic growth, and r were found for all cladoceran species, especially when the proportion of CYLCAM-2 was higher than 50% in relation to green algae in a fixed total food concentration. Our results suggest that both nutritional (C/P and morphology) and toxicity factors can act to impair cladoceran fitness and help explain the absence of cladocerans in Camorim reservoir.


Assuntos
Cladóceros/efeitos dos fármacos , Cianobactérias/química , Daphnia/efeitos dos fármacos , Fitoplâncton/química , Animais , Bioensaio , Brasil , Clorófitas , Cylindrospermopsis , Daphnia/química , Alimentos
10.
Nature ; 566(7743): 205-211, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30760914

RESUMO

Uncertainty in the global patterns of marine nitrogen fixation limits our understanding of the response of the ocean's nitrogen and carbon cycles to environmental change. The geographical distribution of and ecological controls on nitrogen fixation are difficult to constrain with limited in situ measurements. Here we present convergent estimates of nitrogen fixation from an inverse biogeochemical and a prognostic ocean model. Our results demonstrate strong spatial variability in the nitrogen-to-phosphorus ratio of exported organic matter that greatly increases the global nitrogen-fixation rate (because phytoplankton manage with less phosphorus when it is in short supply). We find that the input of newly fixed nitrogen from microbial fixation and external inputs (atmospheric deposition and river fluxes) accounts for up to 50 per cent of carbon export in subtropical gyres. We also find that nitrogen fixation and denitrification are spatially decoupled but that nevertheless nitrogen sources and sinks appear to be balanced over the past few decades. Moreover, we propose a role for top-down zooplankton grazing control in shaping the global patterns of nitrogen fixation. Our findings suggest that biological carbon export in the ocean is higher than expected and that stabilizing nitrogen-cycle feedbacks are weaker than previously thought.


Assuntos
Organismos Aquáticos/metabolismo , Fixação de Nitrogênio , Nitrogênio/metabolismo , Fitoplâncton/metabolismo , Zooplâncton/metabolismo , Animais , Organismos Aquáticos/química , Atmosfera/química , Carbono/metabolismo , Sequestro de Carbono , Retroalimentação , Mapeamento Geográfico , Nitrogênio/análise , Oceanos e Mares , Fósforo/análise , Fósforo/metabolismo , Fitoplâncton/química , Rios/química , Zooplâncton/química
11.
Appl Spectrosc ; 73(1): 104-114, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30012006

RESUMO

The use of rotating filter wheels is common in photometric applications. Traditional filter wheel designs typically exhibit a number of filter openings spaced evenly about the circumference of the wheel. In this work we examine a number of shortcomings of this traditional filter design in measurements of phytoplankton fluorescence made with our fluorescence imaging photometer (FIP). We present an alternative asymmetric wheel design that offers a number of advantages over the traditional design as well as a new processing algorithm designed to accommodate convolution of signals from adjacent channels inherent in measurements collected with the asymmetric design. This approach eliminates the need for a separate signal to establish timing and wheel position, unambiguously establishes filter order even when the direction of rotation is unknown, allows for better estimates of signal baseline, and is more resilient to effects of vibration and other dynamic processes that could occur on the time scale of wheel rotation. We demonstrate performance improvements for phytoplankton fluorescence measurements associated with the new wheel design and algorithm compared with previously published methods using the FIP. Both the improved image processing algorithm and filter wheel design were found to reduce noise in our measurements significantly.


Assuntos
Algoritmos , Processamento de Imagem Assistida por Computador/métodos , Imagem Óptica/métodos , Fitoplâncton , Desenho de Equipamento , Microscopia de Fluorescência/instrumentação , Microscopia de Fluorescência/métodos , Imagem Óptica/instrumentação , Fotometria/instrumentação , Fotometria/métodos , Fitoplâncton/química , Fitoplâncton/citologia
12.
Appl Spectrosc ; 73(3): 304-312, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30345799

RESUMO

Phytoplankton play a vital role as primary producers in aquatic ecosystems. One common approach to classifying phytoplankton is fluorescence excitation spectroscopy, which leverages the variation in types and concentrations of pigments among different phytoplankton taxonomic groups. Here, we used a fluorescence imaging photometer to measure excitation ratios ("signatures") of single cells and bulk cultures of seven differently pigmented phytoplankton species as they progressed from nitrogen N-replete to N-depleted conditions. Our objective was to determine whether N depletion alters the fluorescence excitation signature of each species and, if so, how quickly they recover when N (as nitrate) was resupplied, because these factors affect our ability to classify the species correctly. Of the seven species studied, only Proteomonas sulcata, a marine cryptophyte, showed measurable changes in single-cell fluorescence excitation ratios and bulk fluorescence excitation spectra. These changes were likely due to decreases in the cellular concentration of phycoerythrin, a N-rich pigment, as N became scarce. Within 3 h of resupply of N, fluorescence signatures began returning to pre-depletion values and were indistinguishable from N-replete cells by 80 h after resupply. These data suggest that our classification approach is robust for non-PE containing phytoplankton. PE-containing phytoplankton might exhibit systematic changes in their signatures depending on their level of N depletion, but this could be detected and the phytoplankton re-classified following a few hours of incubation in N replete conditions.


Assuntos
Fluorescência , Nitrogênio/metabolismo , Fitoplâncton/química , Análise de Célula Única , Espectrometria de Fluorescência/métodos
13.
Spectrochim Acta A Mol Biomol Spectrosc ; 210: 405-411, 2019 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-30530100

RESUMO

In view of the adverse effects of CDOM (chromophoric or colored dissolved organic matter) on in vivo algal pigment concentration measurements in natural water bodies, a CDOM influence correction method for algal concentration measurements based on three-dimensional fluorescence spectra is investigated. The three-dimensional fluorescence spectra of five common species of algae belonging to five categories, HA (humic acid), and natural water sampled from the Dongpu reservoir, Hefei were analyzed, and the spectral similarity of endogenous/exogenous CDOM in the algal fluorescence spectra region was compared. HA was selected to represent the CDOM spectrum group. The CDOM modified algal pigment concentration measurement method was developed using three-dimensional fluorescence spectra coupled with non-negative weighted least squares linear regression analysis. The results show that under the presence of CDOM interference factors, the recognition accuracy rate of Pyrrophyta, Bacillariophyta, Cyanophyta, and Chlorophyta increased 100%, 100%, 40%, and 40%, respectively. The average recovery rate of Cryptomonas, Pyrrophyta, Bacillariophyta, and Chlorophyta increased 162.7%, 50.3%, 106.4%, and 19.1%, respectively. In addition, the classification accuracy of Pyrrophyta, Bacillariophyta, Cyanophyta, Chlorophyta increased 83.9%, 100%, 38.2%, and 48%, respectively. This was concluded by comparing these results with the results of the algal pigment concentration measurement method without the CDOM modification. This study provides an experimental basis for the development of accurate phytoplankton fluorescence classification monitoring technology.


Assuntos
Clorófitas , Cianobactérias , Diatomáceas , Espectrometria de Fluorescência/métodos , Clorofila A/análise , Dinoflagelados , Monitoramento Ambiental/métodos , Fluorescência , Substâncias Húmicas , Imagem Tridimensional , Análise dos Mínimos Quadrados , Fitoplâncton/química , Espectrometria de Fluorescência/estatística & dados numéricos
14.
PLoS One ; 13(12): e0208010, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30550568

RESUMO

Trichodesmium, a filamentous bloom-forming marine cyanobacterium, plays a key role in the biogeochemistry of oligotrophic ocean regions because of the ability to fix nitrogen. Naturally occurring in the Great Barrier Reef (GBR), the contribution of Trichodesmium to the nutrient budget may be of the same order as that entering the system via catchment runoff. However, the cyclicity of Trichodesmium in the GBR is poorly understood and sparsely documented because of the lack of sufficient observations. This study provides the first systematic analysis of Trichodesmium spatial and temporal occurrences in the GBR over the decade-long MERIS ocean color mission (2002-2012). Trichodesmium surface expressions were detected using the Maximum Chlorophyll Index (MCI) applied to MERIS satellite imagery of the GBR lagoonal waters. The MCI performed well (76%), albeit tested on a limited set of images (N = 25) coincident with field measurements. A north (Cape York) to south (Fitzroy) increase in the extent, frequency and timing of the surface expressions characterized the GBR, with surface expressions extending over several hundreds of kilometers. The two southernmost subregions Mackay and Fitzroy accounted for the most (70%) bloom events. The bloom timing of Trichodesmium varied from May in the north to November in the south, with wet season conditions less favorable to Trichodesmium aggregations. MODIS-Aqua Sea Surface Temperature (SST) datasets, wind speed and field measurements of nutrient concentrations were used in combination with MCI positive instances to assess the blooms' driving factors. Low wind speed (<6 m.s-1) and SST > 24°C were associated with the largest surface aggregations. Generalized additive models (GAM) indicated an increase in bloom occurrences over the 10-year period with seasonal bloom patterns regionally distinct. Interannual variability in SST partially (14%) explained bloom occurrences, and other drivers, such as the subregion and the nutrient budget, likely regulate Trichodesmium surface aggregations in the GBR.


Assuntos
Recifes de Corais , Eutrofização , Fitoplâncton/fisiologia , Estações do Ano , Trichodesmium/fisiologia , Austrália , Clorofila/análise , Conjuntos de Dados como Assunto , Monitoramento Ambiental/métodos , Monitoramento Ambiental/estatística & dados numéricos , Fitoplâncton/química , Temperatura Ambiente , Trichodesmium/química , Vento
15.
Mar Drugs ; 16(11)2018 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-30441860

RESUMO

Cyclic imine toxins are neurotoxic, macrocyclic compounds produced by marine dinoflagellates. Mass spectrometric screenings of extracts from natural plankton assemblages revealed a high chemical diversity among this toxin class, yet only few toxins are structurally known. Here we report the structural characterization of four novel cyclic-imine toxins (two gymnodimines (GYMs) and two spirolides (SPXs)) from cultures of Alexandrium ostenfeldii. A GYM with m/z 510 (1) was identified as 16-desmethylGYM D. A GYM with m/z 526 was identified as the hydroxylated degradation product of (1) with an exocyclic methylene at C-17 and an allylic hydroxyl group at C-18. This compound was named GYM E (2). We further identified a SPX with m/z 694 as 20-hydroxy-13,19-didesmethylSPX C (10) and a SPX with m/z 696 as 20-hydroxy-13,19-didesmethylSPX D (11). This is the first report of GYMs without a methyl group at ring D and SPXs with hydroxyl groups at position C-20. These compounds can be conceived as derivatives of the same nascent polyketide chain, supporting the hypothesis that GYMs and SPXs are produced through common biosynthetic genes. Both novel GYMs 1 and 2 were detected in significant amounts in extracts from natural plankton assemblages (1: 447 pg; 2: 1250 pg; 11: 40 pg per mL filtered seawater respectively).


Assuntos
Dinoflagelados/química , Compostos Heterocíclicos com 3 Anéis/química , Hidrocarbonetos Cíclicos/química , Iminas/química , Toxinas Marinhas/química , Fitoplâncton/química , Compostos de Espiro/química , Compostos Heterocíclicos com 3 Anéis/isolamento & purificação , Hidrocarbonetos Cíclicos/isolamento & purificação , Iminas/isolamento & purificação , Toxinas Marinhas/isolamento & purificação , Estrutura Molecular , Compostos de Espiro/isolamento & purificação
16.
Sci Rep ; 8(1): 16285, 2018 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-30390006

RESUMO

Diatoms can represent the major component of phytoplankton and contribute massively to global primary production in the oceans. Over tens of millions of years they developed an intricate porous silica shell, the frustule, which ensures mechanical protection, sorting of nutrients from harmful agents, and optimization of light harvesting. Several groups of microalgae evolved different strategies of protection towards ultraviolet radiation (UVR), which is harmful for all living organisms mainly through the formation of dimeric photoproducts between adjacent pyrimidines in DNA. Even in presence of low concentrations of UV-absorbing compounds, several diatoms exhibit significant UVR tolerance. We here investigated the mechanisms involved in UVR screening by diatom silica investments focusing on single frustules of a planktonic centric diatom, Coscinodiscus wailesii, analyzing absorption by the silica matrix, diffraction by frustule ultrastructure and also UV conversion into photosynthetically active radiation exerted by nanostructured silica photoluminescence. We identified the defects and organic residuals incorporated in frustule silica matrix which mainly contribute to absorption; simulated and measured the spatial distribution of UVR transmitted by a single valve, finding that it is confined far away from the diatom valve itself; furthermore, we showed how UV-to-blue radiation conversion (which is particularly significant for photosynthetic productivity) is more efficient than other emission transitions in the visible spectral range.


Assuntos
Parede Celular/química , Diatomáceas/fisiologia , Nanoestruturas/química , Fitoplâncton/fisiologia , Raios Ultravioleta/efeitos adversos , Aclimatação/fisiologia , Parede Celular/efeitos da radiação , Diatomáceas/química , Diatomáceas/efeitos da radiação , Nanoestruturas/efeitos da radiação , Oceanos e Mares , Fitoplâncton/química , Fitoplâncton/efeitos da radiação , Porosidade , Dióxido de Silício/química
17.
Mar Pollut Bull ; 135: 1198-1204, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30301019

RESUMO

The North Yellow Sea is a major aquaculture production area for the scallop Patinopecten yessoensis. In this study, the temporal and spatial variation of phycotoxins in scallops, phytoplankton, and their cysts were analyzed during a survey conducted from June 2011 to April 2012 around Zhangzi Island. The study area is a semi-enclosed epicontinental sea surrounded by the Shandong Peninsula, the Liaodong Peninsula and the Korean Peninsula. The three main results of the study were as follows: (1) The saxitoxin-group toxins, okadaic acid and analogues, and pectenotoxins were the major phycotoxin residues found in scallops; (2) Six kinds of toxic microalgae were identified, Protoperidinium spp., Gonyaulax spp., and Alexandrium spp. were the dominant taxa; Seven types of potential marine toxin-producing dinoflagellates, A. tamarense, A. catenella, Dinophysis fortii, G. catenatum, Gambierdiscus toxicus, Azadinium poporum, and Pseudo-nitzschia pungen were identified as the primary source of phycotoxins and were present at relatively high density from June to October; and (3) azaspiracids and domoic acid might be new potential sources of toxin pollution. This study represents the first assessment to phycotoxins around Zhangzi Island in the North Yellow Sea.


Assuntos
Contaminação de Alimentos/análise , Toxinas Marinhas/análise , Pectinidae/química , Fitoplâncton , Frutos do Mar/análise , Animais , Aquicultura/métodos , China , Diatomáceas , Dinoflagelados , Microalgas , Oceanos e Mares , Fitoplâncton/química , Saxitoxina/análise , Estações do Ano , Análise Espaço-Temporal , Compostos de Espiro/análise
18.
Sci Data ; 5: 180226, 2018 10 23.
Artigo em Inglês | MEDLINE | ID: mdl-30351308

RESUMO

Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent problem resulting from nutrient pollution and climate-change induced stressors, like poor transparency, increased water temperature and enhanced stratification. Consistency in data collection and analysis methods is necessary to achieve fully comparable datasets and for statistical validity, avoiding issues linked to disparate data sources. The European Multi Lake Survey (EMLS) in summer 2015 was an initiative among scientists from 27 countries to collect and analyse lake physical, chemical and biological variables in a fully standardized manner. This database includes in-situ lake variables along with nutrient, pigment and cyanotoxin data of 369 lakes in Europe, which were centrally analysed in dedicated laboratories. Publishing the EMLS methods and dataset might inspire similar initiatives to study across large geographic areas that will contribute to better understanding lake responses in a changing environment.


Assuntos
Cianobactérias/química , Monitoramento Ambiental , Lagos , Mudança Climática , Europa (Continente) , Fitoplâncton/química , Pigmentos Biológicos
19.
Opt Express ; 26(15): 18863-18877, 2018 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-30114147

RESUMO

A multi-excitation fluorometer (MFL, JFE Advantech Co., Ltd.), originally designed to discriminate between phytoplankton species present within a population, has been redirected for use in fluorescence quantum yield (FQY) determination. While this calibration for apparent FQY requires no modification of the MFL, it is necessary to have an independent measurement of the spectral absorption coefficient of the subject fluid. Two different approaches to calibration were implemented. The primary method made use of reference fluorescent dye solutions of known quantum yield. The second method made use of acrylic fluorescent plaques and films. The two methods yielded consistent results, except in the 570 and 590 nm LED channels of the MFL. Application of the MFL in FQY determination is illustrated with an in situ Southern Ocean sample.


Assuntos
Clorofila/análise , Fluorescência , Fluorofotometria/instrumentação , Fitoplâncton/química , Calibragem , Clorofila A , Monitoramento Ambiental
20.
J Microbiol Methods ; 152: 109-118, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30077695

RESUMO

The maintenance of pH homeostasis is critical for a variety of cellular metabolic processes. Although ocean acidification is likely to influence cellular metabolism and energy balance, the degree to which intracellular pH in phytoplankton differs from the external environment under varying environmental pH levels is not well characterized. While there are numerous existing methods for the determination of intracellular pH in the form of single peak emission (e.g., BCECF) and radioisotopic (e.g., 14C-DMO) indicators for use with phytoplankton, the fluorescent pH indicator seminaphtharhodafluor (SNARF) has not been established as a robust method for measuring in vivo pH in phytoplankton. SNARF has superior accuracy and sensitivity since it exhibits dual emission peaks from a single excitation wavelength and the ratio of the two are related to pH. The use of a ratio limiting variations in fluorescence due to dye loading, photobleaching, and instrument variation; moreover, like other fluorescence-based assays, it does not require the specialized equipment and permits that radioisotopic methods do. As a first step, we tested the performance of SNARF for measuring intracellular pH in vivo in a number of phytoplankton taxa. SNARF detection was accomplished using fluorescence spectroscopy (FS) and laser scanning microscopy (LSM). Since SNARF fluorescence is activated by cleavage of an ester group from the core fluorophore by non-specific esterases, we measured esterase activity using fluorescein diacetate (FDA) to characterize variability in esterase activity among phytoplankton taxa, with a view towards its influence on assay performance. Esterase activity cell volume; however, there was no indication that enzyme specificity and differences in individual esterase profiles adversely affected SNARF performance in phytoplankton. Assays of intracellular pH using SNARF were comparable to those made with 14C-labeled DMO, an accepted standard method. Thus, SNARF provides robust measurements of intracellular pH in phytoplankton, constituting a useful tool in investigations of the effects of ocean acidification and fluctuations in environmental pH on cellular physiology.


Assuntos
Benzopiranos , Citoplasma/química , Corantes Fluorescentes , Fitoplâncton/química , Espectrometria de Fluorescência/métodos , Calibragem , Citoplasma/enzimologia , Técnicas de Diagnóstico por Radioisótopos , Ensaios Enzimáticos/métodos , Esterases/metabolismo , Fluoresceínas , Fluorescência , Corantes Fluorescentes/análise , Homeostase , Concentração de Íons de Hidrogênio , Microscopia Confocal/métodos , Fitoplâncton/enzimologia , Salinidade , Sensibilidade e Especificidade , Espectrometria de Fluorescência/normas
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA