Afef Fathalli, Mohamed S. Romdhane, Vitor Vasconcelos, Amel Ben Rejeb Jenhani; Biodiversity of cyanobacteria in Tunisian freshwater reservoirs: occurrence and potent toxicity — a review. In spite of the great environmental and sanitary importance of cyanobacteria, their biodiversity is little known in Tunisia. In this work, a review was carried out, based on literature data, of potentially toxic cyanobacteria occurrence in Tunisia.

Microcystis, one of the most widely distributed toxic bloom-forming cyanobacteria genera, was represented by Microcytis wesenbergii, found only in Lebna water reservoir, and Microcytis aeruginosa recorded in different water bodies.

The invasive potentially toxic cyanobacterium Cylindrospermopsis raciborskiireported for the first time in Tunisia in Octoberwas observed in the semi-arid to arid areas.

The harmful genus Planktothrix was represented in Tunisian freshwater by the green-pigmented species P. The filamentous cyanobacteria dominance is increasingly reported in Tunisia in eutrophic water bodies. This dominance increases especially during the summer—autumn period.

Recently, potentially toxic cyanobacteria blooms have been reported in some reservoirs in the north east of the country. These blooms were generated by the potentially toxic Chroococcale Microcystis aeruginosa. Harmful cyanobacteria tend to spatio-temporal expansion in the Tunisian inland waters. The toxicological potential evaluated by several methods showed that none of the Tunisian strains were proved to be cylindrospermopsin nor saxitoxin producers.

However, the majority of Microcystis were able to synthesize microcystin. Cyanobacteria are a major group of prokaryotes that occur throughout the world WHO They are the Earth's oldest known oxygen-producing organisms, with fossil remains dating back million years Schopf The tragic deaths of 70 of patients exposed to the hepatotoxins microcystins MC through renal dialysis in Brazil are the only well known substantiated human fatalities due to cyanotoxins Jochimsen et al.

Nevertheless, some illnesses reported previously were life-threatening Ressom et al. The most common cyanobacterial genera known for their potential ability to produce toxins include Anabaena, Aphanizomenon, Cylindrospermopsis, Lyngbya, Microcystis, Nodularia, Nostoc and Planktothrix. In fact, Ballot et al. Kosten et al. They found that the percentage contribution of cyanobacteria in total phytoplankton biomass increases significantly with temperature.

These authors noted also that the rise in temperature can reduce the levels of nutrient uptake that cause the initiation and maintenance of blooms. The warm Mediterranean climate favors the occurrence and extended duration of the cyanobacterial blooms in eutrophic freshwaters, which may start in spring and persist until December, or in hypertrophic lakes, may even be continuous throughout the year Moustaka-Gouni et al.

Although toxic and non-toxic strains usually co-exist in a water body, distinguishing toxic strains from non-toxic strains is impossible under a microscope.E Corresponding author.

Email: buzunov uni-sofia. This paper describes the first use of aerial observations by a drone as an additional means for choosing sampling points during field studies of cyanobacterial harmful algal blooms CyanoHABs in selected Bulgarian waterbodies and the use of HPLC analysis of marker pigments for the fast determination of phytoplankton composition and biomass.

The finding of cylindrospermopsin is the first in Bulgaria, the detection of saxitoxins is the first for Durankulak Lake and the microcystins records are the first for Sinyata Reka Reservoir. Considering the high total number of wetlands in Bulgaria, many of which are lowland, small and shallow and therefore vulnerable to CyanoHABs, we recommend further use of drones and HPLC in monitoring, which should speed up detection and reduce sampling efforts while enabling valuable information to be gathered.

Additional keywords: cyanobacteria, cyanoprokaryotes, cyanotoxins, cylindrospermopsin, microcystins, phytoplankton, saxitoxins. Advances in the aquatic sciences.

first observation of microcystins in tunisian inland waters: a

Shopping Cart: empty. Search our journals. Previous Next Contents Vol 71 5. Abstract This paper describes the first use of aerial observations by a drone as an additional means for choosing sampling points during field studies of cyanobacterial harmful algal blooms CyanoHABs in selected Bulgarian waterbodies and the use of HPLC analysis of marker pigments for the fast determination of phytoplankton composition and biomass.

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Hepatotoxic Seafood Poisoning (HSP) Due to Microcystins: A Threat from the Ocean?

Microcystins MCs produced by cyanobacteria pose a serious threat to public health. Intelligence on MCs distributions in freshwater is therefore critical for environmental agencies, water authorities, and public health organizations. We developed and validated an empirical model to quantify MCs in Lake Taihu during cyanobacterial bloom periods using the atmospherically Rayleigh-corrected moderate resolution imaging spectroradiometer MODIS-Aqua R rc products and in situ data by means of chlorophyll a concentrations Chl a.

Then, a regional algorithm to analyze MCs in Lake Taihu was constructed by combining the two relationships. MCs in the lake were markedly variable both spatially and temporally. Cyanobacterial bloom scums, temperature, wind, and light conditions probably affected the temporal and spatial distribution of MCs in Lake Taihu.

The findings demonstrate that remote sensing reconnaissance in conjunction with in situ monitoring can greatly aid MCs assessment in freshwater. Distributions of sampling sites.

ESA Echoes in Space - Hazard: Flood mapping with Sentinel-1

List of the testing spectral indices for deriving Chl a information. The American Chemical Society holds a copyright ownership interest in any copyrightable Supporting Information.

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Article Views Altmetric. Citations Supporting Information. Cited By. This article is cited by 58 publications. Giesy, and Hongxia Yu. A machine learning approach to estimate chlorophyll-a from Landsat-8 measurements in inland lakes. Remote Sensing of Environment, Properties of CaO2 for H2O2 release and phosphate removal and its feasibility in controlling Microcystis blooms. Thackeray, Stephanie E.

The case for research integration, from genomics to remote sensing, to understand biodiversity change and functional dynamics in the world's lakes. Global Change Biology26 6 Cyanobacterial bloom expansion caused by typhoon disturbance in Lake Taihu China. Quantifying the dependence of cyanobacterial growth to nutrient for the eutrophication management of temperate-subtropical shallow lakes.

Bio-optical Modeling and Remote Sensing of Inland Waters

Water Research, In-situ, high-resolution evidence from water-sediment interface for significant role of iron bound phosphorus in eutrophic lake.An experimental study was performed in to investigate the polluting effect of eutrophic inland waters communicating with the sea coast.

The study was planned after a heavy and long-lasting Planktothrix rubescens bloom occurred in the Lake Occhito, an artificial reservoir. The waters of the reservoir flow into the southern Adriatic Sea, near several marine breeding of Mytilus galloprovincialis mussels, a typical seafood from the Apulia region Southern Italy. A monitoring study of water and mussels from the sea coast of northern Apulia region and on the Occhito reservoir was carried out over twelve months, to get more information regarding the contamination by cyanobacteria and related cyanotoxins.

Elisa immunoassay analyses estimated total microcystin amounts from 1. Analyses of some samples of free-living marine clams as well as of marine and freshwater fish proved microcystin contamination. Our study describes for the first time the direct relationship between environmental pollution and food safety, caused by seafood contamination from freshwater toxic blooms. Most poisoning risks from cyanobacteria blooms are due to microcystins MCa group of cyclic heptapeptides causing acute and chronic effects derived from their endocellular activity and protein phosphatase inhibition.

Microcystins are hepatotoxins [ 1 — 6 ] acting as specific inhibitors of protein phosphatases 1, 2A [ 4 ], 3 MC-LA [ 7 ], 4 and 5 [ 8 ], and to a minor extent PP 2B [ 9 ].

They dephosphorylate serine and threonine residues in animals and plants. The inhibition of PP1 and PP2A increases the phosphorylation of proteins in liver cells, affecting several processes like metabolism, cell contractility, membrane transport, secretion, cell division, and gene transcription and translation. MCs are responsible for liver failure and death in humans [ 310 ], wild animals, livestock, and aquatic life [ 1112 ].

Hepatotoxic [ 34 ] endocrine disrupting [ 13 — 17 ] and oncogene activating [ 18 ] effects have been described for these toxins, classified as 2B compounds in the IARC oncogenic scale [ 19 ]. Indirect evidence supporting tumour promotion of human cancer from exposure to MCs is derived from the studies of Yu [ 20 ], Ueno et al. MCs have synergic effects too, well documented in experimental studies on mice [ 25 ]. In these studies, daily subacute doses of MCs, administered intranasally to mice for 7-day periods, caused pathologic effects two times stronger than those produced by the sum of the MCs administered as a single dose.

Bioaccumulation has been proposed to be responsible for this effect [ 26 ]. Several large scale fish death outbreaks have been associated to massive occurrence of cyanobacteria in water bodies [ 27 — 29 ]. Studies on fish contaminations showed species-specific sensitivities to microcystins; the uptake of these cyanotoxins in fish results primarily from oral ingestion and to a minor extent from absorption via the gill epithelium [ 30 ].

The toxicity of microcystins in fish depends on the balance between accumulation and metabolism [ 31 ], and the observed species-specific sensitivities have been interpreted as the result of anatomical, physiological, and behavioural differences and detoxification capacities via the glutathione-S-transferase pathway among the various fish orders [ 32 — 34 ].

first observation of microcystins in tunisian inland waters: a

In the past, health risks for consumers from gutted fish were traditionally considered negligible, because liver was considered the main target for bioaccumulation of microcystins. Recent studies, however, detected significant concentrations of microcystins in the muscle of wild and farmed fish, at The most studied cyanobacterial toxins belong to a family of cyclic heptapeptide hepatotoxins, called microcystins.

The microcystins are stable hydrophilic cyclic heptapeptides with a potential to cause cell damage following cellular uptake via organic anion-transporting proteins OATP. Their intracellular biologic effects presumably involve inhibition of catalytic subunits of protein phosphatases PP1 and PP2A and glutathione depletion.

The microcystins produced by cyanobacteria pose a serious problem to human health, if they contaminate drinking water or food. These toxins are collectively responsible for human fatalities, as well as continued and widespread poisoning of wild and domestic animals. Although intoxications of aquatic organisms by microcystins have been widely documented for freshwater ecosystems, such poisonings in marine environments have only occasionally been reported.

Moreover, these poisonings have been attributed to freshwater cyanobacterial species invading seas of lower salinity e. However, recent data suggest that microcystins are also being produced in the oceans by a number of cosmopolitan marine species, so that Hepatotoxic Seafood Poisoning HSP is increasingly recognized as a major health risk that follows consumption of contaminated seafood.

Cyanobacterial toxins cyanotoxins belong to diverse chemical classes and can cause cell-specific toxic events, such as neurotoxicity by anatoxin-a, anatoxin-a.

Following the drinking of contaminated water, livestock poisoning and adverse human health effects have been reported. The World Health Organization WHO has published both a guideline value for the most prevalent cyanotoxin in drinking water and a procedural guideline for recreational waters [ 5 ]. Among cyanotoxins, the cyclic hepatotoxins, nodularins Nods and microcystins MCsare the most common natural toxins [ 36 ]. Nodularins are produced only by strains of the genus, Nodularia, and thus, any reported poisoning due to Nods can be confidently attributed to this genus [ 78 ].

This is not the case for MCs, by far the most prevalent of the cyanobacterial toxins, which are produced by strains of distantly related genera, such as MicrocystisAnabaenaPlanktothrix and, more rarely, AnabaenopsisHapalosiphon and Nostoc [ 6910 ].

Microcystins are synthesized non-ribosomally by the thiotemplate functions of large multifunctional enzyme complexes containing both non-ribosomal peptide synthetase PS and polyketide synthase PKS [ 11 ].

The microcystin biosynthesis gene cluster mcyS has been sequenced and partially characterized in several cyanobacterial freshwater species [ 121314 ]. In Microcystis aeruginosathe microcystin biosynthesis gene cluster mcyS spans 55 kb, comprises 10 genes arranged in two divergently transcribed operons mcyA—C and mcyD—J and includes genes encoding peptide synthetases mcyAmcyB and mcyCpolyketide synthases mcyDhybrid PS—PKS enzymes mcyEmcyG and enzymes putatively involved in the tailoring mcyJmcyF and mcyI and transporting mcyH of the toxin [ 12 ].

Comparison of mcyS gene clusters from different genera revealed differences both in gene arrangements and nucleotide sequences. Comparison of microcystin synthetase genes G and polypeptides P from different cyanobacteria species or strains with those sequenced from Anabaena strain Percentages in parentheses referred to query coverage.

References for the sequences: Anabaena sp. Based on these sequence differences, Rantala and collaborators developed genus specific primer sets in order to identify putative toxic cyanobacterial genera in mixed freshwater cyanobacterial populations [ 18 ]. Microcystin production in toxic cyanobacteria is thought to be influenced by a number of different physical and environmental parameters, such as nitrogen, phosphorus, trace metals, temperature, light and pH [ 19202122 ].

Nevertheless, although the above mentioned environmental factors are associated with toxin production, no models exist that can predict toxin concentrations in natural ecosystems [ 10 ]. At the molecular level, high light intensities and red light were found to increase transcription of the mcyS gene cluster, while blue light led to reduced transcript levels [ 23 ]. Recently, it was found that NtcA, a transcription factor that has been characterized for a variety of cyanobacterial species, binds to the mcyS promoter from M.

While NtcA is produced at a basal level in the presence of ammonium and the level is elevated under nitrogen stress conditions [ 25262728 ], it has been suggested that the regulation of microcystin synthetase gene transcription is responsive to nitrogen.

The letters X and Y represent positions that are occupied by variable l -amino acids.Bio-optical Modeling and Remote Sensing of Inland Waters presents the latest developments, state-of-the-art, and future perspectives of bio-optical modeling for each optically active component of inland waters, providing a broad range of applications of water quality monitoring using remote sensing.

Rather than discussing optical radiometry theories, the authors explore the applications of these theories to inland aquatic environments. The book not only covers applications, but also discusses new possibilities, making the bio-optical theories operational, a concept that is of great interest to both government and private sector organizations.

In addition, it addresses not only the physical theory that makes bio-optical modeling possible, but also the implementation and applications of bio-optical modeling in inland waters. Early chapters introduce the concepts of bio-optical modeling and the classification of bio-optical models and satellite capabilities both in existence and in development.

Later chapters target specific optically active components OACs for inland waters and present the current status and future direction of bio-optical modeling for the OACs. Concluding sections provide an overview of a governance strategy for global monitoring of inland waters based on earth observation and bio-optical modeling. Upper-Level undergraduate and graduate level students, researchers and professors in aquatic sciences, ecology, remote sensing, and environmental science.

Chapter 1. Mishra and Anatoly A. Chapter 3. Chapter 4. Kallio, Tonio Fincke and Birgot Paavel. Chapter 5. Chapter 6. Chapter 7. Chapter 9. His research on radiative transfer model and water column correction procedure to map underwater coral reef habitats from space have been citied in numerous journal articles and replicated by many researchers and resource managers. His research on predicting toxic algal growth cyanobacteria and phytoplankton in inland waters has attracted attention of agencies such as GA Power, EPA, and Center for Disease Control.

Geographer by degree and limnologist by heart Ogashawara found through remote sensing the opportunity to connect these two areas. Since high school he learned about tropical limnology while researching at the International Institute of Ecology, Brazil.

During college he worked on relating weather types and cyanobacteria blooms and as an MSc student at the Brazilian National Institute for Space Research, he attempted to use bio-optical modeling to monitor water quality in tropical hydroelectric reservoirs. Currently he is a PhD student at Indiana University — Purdue University at Indianapolis, working with bio-optical modeling to identify and predict cyanobacteria in inland waters.

first observation of microcystins in tunisian inland waters: a

His research on radiative transfer in terrestrial vegetation and water resulted in development models for estimating water constituent concentrations and pigment contents in vegetation. They have been citied in numerous journal articles and used widely around the world. Gitelson serves on the Editorial board of several journals, Remote Sensing of Environment and Remote Sensing are among them.

We are always looking for ways to improve customer experience on Elsevier. We would like to ask you for a moment of your time to fill in a short questionnaire, at the end of your visit. If you decide to participate, a new browser tab will open so you can complete the survey after you have completed your visit to this website.He is clearly quarterback Tom Savage's favorite target and should see no fewer than double-digit passes thrown his way.

Hopkins will face a San Francisco 49ers team that ranks just 26th out of 32 NFL teams against No. They also allow 7. Fuller's calling card is catching the deep ball (he averages 19. In fairness, few players can match Watson's ability to hit his receivers deep, but Savage should still favor Hopkins in this game.

On the opposite sideline, look for San Francisco 49ers wide receiver Marquise Goodwin to have a breakout performance. Over the past four weeks, it seems as though the former Texas Longhorn has been knocking on the door of a monster day after a slow start to the season.

During that time span, Goodwin has caught 15 passes for 328 yards and one 83-yard touchdown in which he beat stout New York Giants cornerback Janoris Jenkins. Furthermore, Goodwin hauled in all eight of his targets for 99 yards in Jimmy Garoppolo's first start with the team. That performance came against the Chicago Bears in Soldier Field. Although the Bears are 3-9, the Vic-Fangio-led defense has been impressive this season: Football Outsiders ranks them in the top half of the league against the run and pass.

The fact that Goodwin was able to go a perfect eight for eight on his targets against an above-average defense on the road with a new starting quarterback is a good sign for future success. Goodwin has an easier matchup this Sunday in Houston's NRG Stadium (which has a retractable roof). Not only will the 49ers be shielded from elements (which can't be said for other wideouts this week), they will also have one of the best matchups on paper.

For the season, the Texans have allowed 7. Houston is missing numerous key pieces on defense (namely defensive end J. Watt and linebacker Whitney Mercilus), and that has clearly hindered its ability to stop teams. Houston has also allowed some big games to opposing wideouts, namely 171 yards and two touchdowns to the Los Angeles Rams' Robert Woods and 175 yards and two scores to the Indianapolis Colts' T.

first observation of microcystins in tunisian inland waters: a

The guess here is that Goodwin adds his name to that list this Sunday. By continuing to use our website, you are agreeing to our use of cookies. You can change your cookie settings at any time. Above what is generally considered acceptable, especially for a price. Offer a bet with odds unfavourable to the other better. Cohen herself acknowledges the odds against her.


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