Occurrence of the First Toxic Microcystis Bloom in a Recent Moroccan Reservoir

Hammou, H. Ait; Latour, Delphine; Samoudi, S.; Mouhri, Khadija; Douma, Mountasser; Robin, Joël; Loudiki, M.

doi:10.1134/s0097807818030028

Cited by 16 publications

(7 citation statements)

References 33 publications

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“…Their metabolism is dominated by the autotrophic lifestyle based on photosynthesis [4]. A possible imbalance of intrinsic and/or extrinsic origin due to the control of nutrient resources can affect water quality and lead to a modification of the structure of biological community dependent on these hydrosystems, favouring the proliferation of certain algal species known as efflorescence [5]. These blooms can have many economic, ecological and even health consequences, because the massive growth of some phytoplankton populations can pose a risk to fish and therefore to consuming populations [6].…”

Section: Introductionmentioning

confidence: 99%

Phytoplankton Dynamics of Mokolo and Mopa Ponds in Bertoua City (East-Cameroon)

Tenkeu¹,

Kamdem²,

Tchatcho³

et al. 2020

OJE

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This study aims to improve the understanding of algal community's dynamics in response to different environmental factors in two dam ponds (Mokolo and Mopa) in the city of Bertoua (East-Cameroon). Physicochemical and biological analyzes were carried out monthly by direct sampling at the surface and using Van Dorn bottle at 1 m depth. The organisms were collected using transparent glass vials of about 500 ml and fixed with 2.5 ml of a lugol solution, then analyzed using the Utermôhl method. Physicochemical analyzes show low transparency (<75 cm) of the ponds despite their shallow depth (≤150 cm), high levels of dissolved oxygen (>60%), BOD 5 (>30 mg/L) and chlorophyll "a" (>30 µg/L). These data made it possible to categorize the Mokolo and Mopa ponds as hypereutrophic with nitrogen as the limiting factor for eutrophication. Biological data show quite diversified ponds with 138 species identified in Mokolo Pond and strongly dominated by Diatoms with 2951 ind. representing 46% of the total abundance. In Mopa Pond, 147 species were identified, mainly represented by Chlorophyceae with 3629 ind. representing 52% of the total abundance. Azpeitia africana (Mokolo) and Eresmophaera gigas (Mopa) were the most represented taxa during the study. This study will have deduced that the structure and dynamics of algal communities are under the control of different factors or processes that interact simultaneously, namely ascending factors or bottom-up corresponding to nutrient resources and sunlight and descending factors or top-down that are exerted by grazing and active physiological substances produced by other algae that are known to influence phytoplankton.

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Section: Introductionmentioning

confidence: 99%

Phytoplankton Dynamics of Mokolo and Mopa Ponds in Bertoua City (East-Cameroon)

Tenkeu¹,

Kamdem²,

Tchatcho³

et al. 2020

OJE

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“…Concerning nutrients, there is a high loss of nitrogenand high denitrification during the stratification period. The anoxic conditions at the bottom of the lake facilitate the reduction of nitrates [18]and the increase of ammonium by denitrification [10].The same phenomenon has been underlined by several authors at the levels of other Moroccan dams [19][20][21].These ammonium values are higher than those found during a study carried out on the same site more than twenty years ago [22]. Nitrates are rapidly consumed at the surface and decrease throughout the water column, while ammonium ions and total phosphorus are consumed at the surface and released by sediments on the lake bottom.…”

Section: Discussionmentioning

confidence: 63%

Impact of drought on water quality in the Youssef Ben Tachafine dam (Souss-Massa region, Morocco)

et al. 2020

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The Massa catchment area has been experiencing an acute rainfall deficit for several years, which has had direct effects on the filling level of the Youssef Ben Tachafine dam. The objective of this work is to study the impact of the drought on the physicochemical quality and the biological balance of this aquatic ecosystem. A monitoring and bi-monthly analyses of the physicochemical and biological parameters (temperature, dissolved oxygen, pH, conductivity, transparency, manganese, iron, nitrate, ammonium, silica, phosphorus, and chlorophyll-a) were carried out from January to December 2019. The considerable drop in the level of the reservoir has had a major impact on the degradation of the water quality of the lake and its trophic status. The analysis of the results showed that the trophic state of the Youssef Ben Tachafine dam is between mesotrophic and hypereutrophic.

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“…Therefore, we proposed to evaluate the anti‐cyanobacterial activity of macrophytes growing wild in Moroccan water bodies and to identify their potential bioactive substances. In this study, ethyl acetate extracts of three macrophytes ( Nasturtium officinale , Potamogeton natans and Ranunculus aquatilis ) were used in experiments to demonstrate their inhibitory effects against M. aeruginosa, a predominant cyanobacteria in reservoirs of Marrakesh area (Oudra et al, 2001; Douma et al ., 2010; Ait Hammou et al ., 2014, 2018; Lahrouni et al, 2016; Samoudi et al ., 2016). We showed that the growth of M. aeruginosa was effectively inhibited by increasing concentrations of ethyl acetate extracts, with inhibition rates reaching 97.09%, 99.01% and 96.68 % for R. aquatilis , N. officinale and P. natans , respectively.…”

Section: Discussionmentioning

confidence: 99%

Inhibitory effect and mechanism of three macrophytes extract on Microcystis aeruginosa growth and physiology

Tazart

Caldeira

Douma

et al. 2020

Water & Environment J

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Macrophytes are a promising source of bioactive compounds with potential applications in the biocontrol of harmful cyanobacteria blooms. In this study, we investigated the inhibitory effects of extracts from three macrophytes (Nasturtium officinale, Potamogeton natans and Ranunculus aquatilis) on Microcystis aeruginosa. We assessed physiological indicators of inhibition on M. aeruginosa, including lipid peroxidation, protein content, superoxide dismutase activity, catalase activity and growth. The chemical composition of the macrophyte extracts and their specific allelochemicals were analysed using high‐performance liquid chromatography (HPLC). Results showed that M. aeruginosa growth was significantly inhibited after 8 days of exposure, with inhibitory rate varying from 96.98% to 99.01%. The macrophyte extracts caused cyanobacterial cell membrane and antioxidant defence system damage. Thirteen different compounds were identified as allelochemical compounds that could be responsible for M. aeruginosa growth inhibition and oxidative stress. Our findings suggest that allelopathic compounds from macrophytes may be used to effectively control cyanobacteria blooms and promote the restoration of aquatic ecosystems.

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Occurrence of the First Toxic Microcystis Bloom in a Recent Moroccan Reservoir

Cited by 16 publications

References 33 publications

Phytoplankton Dynamics of Mokolo and Mopa Ponds in Bertoua City (East-Cameroon)

Phytoplankton Dynamics of Mokolo and Mopa Ponds in Bertoua City (East-Cameroon)

Impact of drought on water quality in the Youssef Ben Tachafine dam (Souss-Massa region, Morocco)

Inhibitory effect and mechanism of three macrophytes extract on Microcystis aeruginosa growth and physiology

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