Satellite detection of Trichodesmium
blooms in the Southwestern Pacific
and the Tonga trench [2]. This area coincides with high nitrogen fixation rates
[3]. There are numerous correlations
between the observations of surface
mats in the ocean and high reflectance
In the oceans, a large portion of the sub- tortum [1]. Observations of Trichodes- on the MODIS satellite, as for example at
Contact Cecile.dupouy@ird.fr
tropical and tropical pelagic areas are mium accumulations (termed mats) the East of New Caledonia in 2002 (Fig.
dominated by oligotrophic
conditions. Thearound
merchant
(Fig. 1b,
Aknowledgement:
FrenchNew
NavyCaledonia
and the by
Aeronaval
Basis 1a)
of and
New2004
Caledonia
is Fig. 1c ,Fig 1 d)
The cyanobacterial
diazotrophfor
commuships,
Navy, R/Vprogram
Alis and with
volunand inand
January
2017 (Fig. 1e). In sumacknowledged
participation
in French
the observation
R/V Batral
R/V Jacques
nity, composed Cartier,
of unicellular,
filamentary
observers
of positive
2003,
at the peak
as well as
Captain and
crew
from theare
IRDthe
R/Vresult
Alis ship.
The MODISmer
image
was provided
by of a moderate
Norman Kuring, NASA.
tous, and diatoms-symbiotic
(DDAs, cell buoyancy which brings together tri- 2001-2003 El Niño, a Trichodesmium
diatom-diazotroph associations) forms chomes and colonies at the sea surface spp maximum of 4,500 trichomes L-1
Figure
captions are every summer [2]. Trichodesmium is was observed in the Loyalty Channel, a
is dominant. Major
species
1True
color
images of the
areaobserved
off New Caledonia
showing
mats in white
around themuch
islands.
Trichodesmium erythraeum Ehrenberg
mainly
around New
Caledonia
concentration
lower than in New
White crosses: Visual observations from the French Navy and corresponding microphotographies
and T. thiebautii Gomont, two species of and Vanuatu and a Katagnymene form Caledonia lagoon surface accumulaof Trichodesmium in formaline samples : a) in November 2002, b) in January and February 2004 c),
Katagnymene (K. pelagica and K. spiralis was observed between Niue Island and tions which can reach 20,000 trichomes
Fi 1d: surface trichodesmium mats from the French Navy ship La Glorieuse
in January 2004.
Lemmerman), and
Richelia
intracelluTonga in
[2].
L-1 [4].
blooms may
Different
forms
of Trichodesmium
areDecember
observed, 2002
T. Erythraeum,
T. Thiebautii,
and Trichodesmium
Katagnymene
laris as components
of
DDAs
[1].
Weak
In
the
southwest
tropical
Pacific,
satspread
to
cover
enormous
sea surface
spiralis mixed.
winds (< 4 m s-1) andFig.
calm
conditions
ellite
and
aerial
observations
showed
areas.
In
December
2014,
a
huge sur1d. A picture of a mat from the Gardian flight in January 2017 (courtesy J. Aucan)
are independent factors
allow image
the ofpresence
of 3000 km
long
sur- Vanuatu
face bloom
detected
by MODIS coincidFig. 2.which
The MODIS
the Trichodesmium
bloom
between
Islands
and New
in December
with
the microscopic
observation
of Trichodesmium
colonies inof Trichodesmium
accumulations ofCaledonia
Trichodesmium
on the 2014
face
blooms
of Trichodesmium,
mainly
ed with observations
surface
samples at
the SPOT station
withofthe
R/VMelanesian
Alis ship ar- mats (Fig. 2a,b) during a SPOT cruise
surface of the sea,
in particular
T. erytharoundvisited
islands
the
http://earthobservatory.nasa.gov/IOTD/view.php?id=85073
raeum, which has a stronger
positive chipelago, i.e. Vanuatu, New Caledonia, on board R/V Alis [5] and was followed
buoyancy than T. thiebautii and T. con- and as far east as the Fijian archipelago until March [6]. Mat observations are
X
X
X
X
Fig. 1a-c) True color MODIS images off New Caledonia showing mats as high reflectance in white around the islands. White crosses: Visual
observations corresponding to microscope micrographs of Trichodesmium in formalin fixed samples collected by the French Navy in: November
2002 (a); January 2004 (b); February 2004 (c). d-f): A mixture of different forms of Trichodesmium observed: T. erythraeum, T. thiebautii, and
Katagnymene spiralis found in observations on satellite images indicated by a cross. g) Surface Trichodesmium mats (from the French Navy
ship La Glorieuse in January 2004). h) Picture of a mat captured during a New Caledonia Gardian airflight in January 2017 (courtesy Jérôme
Aucan).
HARMFUL ALGAE NEWS NO. 57 / 2017
9
Harmful Algae News An IOC Newsletter on Toxic Algae and Algal Blooms No. 57 - June 2017 www.ioc-unesco.org/hab Unusual fish killing blooms of Tripos furca in Van Phong Bay, South Viet Nam In the beginning of November 2016, a phytoplankton bloom was observed by fisherman in Van Phong Bay, Viet Nam
Fig. 2. Chl-a distribution in coastal waters of Khanh Hoa province during 14th October to 25th November 2016 (sources: MODIS-Aqua Level 2 images, NASA). Clear skies were observed on 14th October, and 11th, 13th, 15th, 22nd, 25th November, while the other days were very cloudy. High chl-a concentrati
vung-sim-2461816/ 3. Nguyen VN et al 2014. In: Kim HG et al (eds) Harmful Algae 2012. Proc15th ICHA (ISSHA) pp 48-51 4. Hodgkiss IJ & Lu S 2004. In: Asian Pacific Phycology in the 21st Century: Prospects and Challenges, pp 215-229 5. Machida M et al 1999. Nippon Suisan Gakk 65: 755756 6. Mat
Mortality of Chilean farmed salmon in wellboats in transit through a Karenia bloom Fig. 1. Geographic distribution of the stations sampled near the Gulf of Penas, Chile, between 31st January and 1st February 2017. A mass mortality of around 170,000 salmon, worth US$ 390,000, was recorded on wellbo
Fig. 3. Density (cells L-1) of Karenia spp. in water samples of the vicinity of the Gulf of Penas. nels, composed mainly of diatoms. Most Karenia (ex Gymnodinum) species produce toxins that can kill fish and other marine organisms when they bloom. In addition to toxicity, some Karenia blooms cause
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ble are toxic harmful dinoflagellates that produce a suite of toxins, including Alexandrium catenella and Gymnodinium catenatum (saxitoxins), Dinophysis caudata (okadaic acid congeners), and benthic HAB (Ostreopsis cf ovata, palytoxins, and Prorocentrum lima, okadaic acid). These toxins can directly
Satellite detection of Trichodesmium blooms in the Southwestern Pacific and the Tonga trench [2]. This area coincides with high nitrogen fixation rates [3]. There are numerous correlations between the observations of surface mats in the ocean and high reflectance In the oceans, a large portion of t
Fig. 2a) MODIS image of the Trichodesmium bloom with white and green mats between Vanuatu Islands and New Caledonia in December 2014; with Landsat 8 zooms on mats superimposed and the microscopic observation of Trichodesmium colonies in surface samples at the SPOT station visited with R/V Alis; b) P
Plankton Planet in New Zealand Plankton Planet is the first citizen science programme designed for biological oceanography. It is a co-operation between scientists and volunteers from the sailing community based on mass sequencing of DNA barcodes from the extracts of plankton communities collected w
Molluscan Shellfish Safety Conference in Ireland Over 230 international delegates from 27 countries participated in the 11th International Conference on Molluscan Shellfish Safety (ICMSS) from Sunday 14 to Thursday 18 May 2017 at the National University of Ireland, Galway. Convened by Irelands Marin
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IV INTERNATIONAL SYMPOSIUM, June 4-8, Washington DC Organized by ICES, PICES, IOC and NOAA Fisheries The 4th International Symposium will bring together experts from around the world to better understand climate impacts on ocean ecosystems and how to respond. The Symposium will Highlight the latest