cyanobacteria and potentially toxin-producing species in lake … · 2019-02-20 · cyanobacteria...
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CyanoCost Action ES1105
Armenia as a near neighbour country
Cyanobacteria and potentially toxin-
producing species in Lake Yerevan (Armenia)
Dr. Arevik Minasyan
UNESCO Chair in Life Sciences
International Post-graduate
Educational Center, Armenia
19-21-th February, 2015, Seville, Spain
Lake Sevan
Lake Sevan –
River Hrazdan –
Lake Yerevan
Cascade
(1965-1968)
40°9′35.04″N and 44°28′36.54″E
Physico-chemical and hydrological characteristics of Lake Yerevan basin
• with typical low mixing, stratified with thermal column formation
• a surface elevation of 908 m
• water level manipulation up to the point of a surface elevation of 895 m (max)
• initial reservoir volume 0.005 km3
• present-day reservoir volume 0.004 km3
• bottom sediments volume about 25% of the initial volume
• shoreline = 6.3 km
• a surface area is 0.65 km2
• a maximal depth of 22 m
• T°C = +1 +2°C - +27 +28°C
• transparency 0.5 - 2 m
• pH = 8.09 – 8.37
(some data were provided by the HAYJRNAKHAGITS INSTITUTE CJSC)
Proportional cyanobacterial biovolume in epilimnion
of Lake Yerevan (May-October, 2012/2013 – X 1 and
X 2 stations; May-October, 2014, X 1 – X 7 stations).
Biovolume calculation was performed with the method after Hillebrand et
al., 1999
Total abundance of cyanobacterial cells in epilimnion of Lake Yerevan
Total abundance of CB in in-shore waters (X 1 – left bank, X 2 – right bank) of Lake Yerevan (cells ml-1) (May-October, 2012/2013/2014)
Total density of CB in photic zone of Lake Yerevan in May-October of 2014 (cells ml-1) (entry – X
3, center – X 4, near-shores – X 6 – left bank, and X 7 – right bank, and exit X 5 (cells ml-1)Sampling stations of Lake Yerevan
Nostoc linckia
Nutrients? or/and Temperature?
less sunny area,
cold and wet,
subdominating by
Aphanothece/
Aphanocapsa
sunny area, hot,
dry dominating
by Microcystis/
Anabaena
intermediate,
transitional area
subdominating by
Planktothrix
Higher NO3- N level shifts the advantage
to Microcystis (Lehman et al. 2009).
10 x NH 4 -N > NO 3 -N > N 2
(Tandeau de Marsac and Houmard 1993)
Microcystis is a phosphate
storage specialist
(Kilham & Hecky 1988)
Microcystis ki = 0.8 h.
(Kromkamp et al. 1989)
“TN/TP rule” > 17 (mol: > 38)
TP = 15 - 100 μg/L
mesotrophic - eutrophic
TN = 401 - 1500 μg/L
meso=-eutrophic
Euphotic zone of Lake Yerevan
is phosphorus-limited
water level
± 13 m ≈ 0.5˚C
Anabaena sp. N:P ratios from 1,000:1 to 10:1
(Nalewajko and Murphy 2001)
Planktothrix agardhii -
high TP and low light
availability conditions.
There are more than 50 morphospecies of Microcystis described, with 20 in temperate regions
and at least 11 in Europe (Komárek & Anagnostidis 1998; Komárek & Komárková 2002).
The main morphospecies of Microcystis in Europe: M. ichthyoblabe (icht) , M. fl os-aquae (f-a), M. aeruginosa (aer), M. Novacekii (nov),
M. viridis (vir), M. wesenbergii (wes); p (plankton), b (benthic). (Photos by Dr. Lenka Šejnohová, in: Ecology of Cyanobacteria II. Their
Diversity in Space and Time. Editor: Prof. Dr. Brian Whitton)
Saxitoxins are classifiedas Scheduled Chemical
Weapons(Metcalf and Codd 2009)
A potential risk assessment
Three Microcystis genera based on oligopeptides spectrum:
• M. aeruginosa with microcystins and aeruginosins,
• M. ichthyoblabe with anabaenopeptins and microginins (Šejnohová et al. 2011);
• M. wesenbergii with cyanopeptolins and unknown peptides (Fastner et al. 2001).
For Anabaena genera based on toxins (Codd et al. 2005)
•microcystins
•anatoxin-a and homoanatoxin-a
•saxitoxins
•cylindrospermopsins
For Planktothrix genera based on toxins (Codd et al. 2005)
•microcystins
•saxitoxins
Internet photos by unknown author photo by A. Minasyan
Microcystis
aeruginosa
Planktothrix
agardhiiAnabaena
planktonica
Anabaena
flos-aquae
Anabaena
circilanis
Water Sports?
Drinking?
Fishing?
Wildlife
conservation?
Irrigation?
Rest
zone?
Microcystins chemically stable molecules
survive extended boiling
(half-life, about 24 h)
and pH = 1 - 10 (Codd and Bell 1996).
Boiling of acidic solutions of saxitoxins induce
more toxic variants (Etheridge 2010).
The Lake Yerevan shoreline
The Hrazdan Gorge
Sewage discharge
Gorge with spring
World Health Organization (WHO, 2003)
for recreational waters
5000 cyanobacterial cells/ml
mild irritative effect
20000 cyanobacterial cells/ml
2– 4 µg microcystin/litre may be expected
up to 10 µg/litre being possible with highly toxic
blooms.
100000 cyanobacterial cells/ml
20 µg microcystin/litre
Microcystis has an average toxin content of
0.2 pg/cell.
Low Risk - < 10 ppb
Moderate Risk - 10-20 ppb
High Risk - > 20 ppb
Guidelines For Cyanobacteria in
Freshwater Recreational
Water Bodies
• Massachusetts Department of Public
Health (MDPH)
• Canadian Guideline
• Australian Guideline
• Oregon Health Authority (OHA)
Actual and/or
potential risk!!!
Clean Waterfor Everybody =
= towards the World’s Better Future
The methods to mitigate water cyanobacterial bloom:
Hypolimnetic aeration to reduce the number of benthic
Microcystis colonies.
Water artificial mixing - specifically to prevent Microcystis
blooms (Chen et al. 2009)
Controlled strategy combining P reduction with the
transport of hypolimnetic water rich in free CO2 to the
epilimnion
Aeration accompanied by light-shading
Recovery of greenzone (especially the shoreline
macrophytic layer)
Hydrogen peroxide for selective suppression of harmful
cyanobacteria (Matthijs, H. & Visser, P., 2012)
Chlorination and ozonation (US EPA)
Mechanical cleaning
Cyanotoxins degradation:
Photocatalytic treatment (TiO2, light absorbtion) (L.Lawton
et al.)
Bacterial degradation of cyanotoxins (the bacterial
species/strains of Sphingomonas, Sphingocinicella,
Arthrobacter, Brevibacterium, Rhodococcus and
Burkholderia (Kato et al. 2009)
TOXIC
CYANOS
Thank you very much
Acknowledgments:
Prof. Dr. Herwig StiborProf. Dr. Linda Lawton
Dr. Triantafyllos Kaloudis