ifremer (*ler/pc l’houmeau, **ler/fbn concarneau) doccuments/cm-2010/n/n2010.pdf · departments...

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Pseudo-nitzschiaaustralis(1)

Pseudo-nitzschia

australis

occurrence and A.S.P. toxicity

in Pertuis Charentais (France) after

Xynthia

storm

(28 feb. 2010)M. Ryckaert*, E. Nézan**, N. Chomérat**, D. Le Gal**, A. Terre-Terrillon**, S. Genauzeau*, A. Derrien*,

A. Schmitt*, A. Fillon*, J. L. Gaignon*

Ifremer (*LER/PC L’Houmeau, **LER/FBN Concarneau)

ICES CM 2010 : N 20

P. BRETON

0,0E+00

5,0E+05

1,0E+06

1,5E+06

JAN FEB MAR APR MAY JUN JUL AUG

P. MAUMUSSON

0,0E+00

5,0E+05

1,0E+06

1,5E+06

JAN FEB MAR APR MAY JUN JUL AUG

P. ANTIOCHE

0,0E+00

5,0E+05

1,0E+06

1,5E+06

JAN FEB MAR APR MAY JUN JUL AUG

Toxicity (Amnesia Shellfish Poisoning -

ASP) within oysters and mussels has been squaring with the development of P. Australis

algae (fig.3a and 3b). Domoic

Acid (DA) health threshold of 20 mg.kg-1

was exceeded for one to two weeks in reared shellfish (fig.4). For the first time since the setting up of REPHY network in relation with the ASP toxin,

administrative authorities of Vendée

and Charente-Maritime departments were thus led to ban harvesting and selling shellfish (and crustacea

as well, tab.2) for one to three weeks in March within all Pertuis

and later in May for one to two weeks in Pertuis

Breton.

Contamination in scallops (Pecten

maximus

tab.1) is longer-

lasted. Their commercial exploitation, scheduled from

October to December, will be decided upon after some new tests are made. But we might worry considering the kinetics of contamination and depuration of these shellfish.

>x5

Fig. 4 ASP accumulation in reared

shellfish

march

march

may

Pseudo-nitzschia

occurrence: maximum monthly quantity

According to the historical data (1998-

2009) from Ifremer

REPHY (Réseau

Phytoplancton

et Phycotoxines) network, the monthly highest quantities of Pseudo-

nitzschia

spp

occur in summer with a

gradient increasing from the north to the south of the Pertuis. During 2010 spring, this gradient has reversed and the highest concentrations were up to 106 cells per liter during the 2nd

fortnight of March (fig.2). The species was identified as

P.australis

(1). It is not a matter of mono-

specific bloom, the development (started before the storm) of the Skeletonema

costatum

diatom is continuing in the same way as the P.australis

development to

reach almost 107 cells per liter.Area location

Among Xynthia

impacts, two of them contributed to enrich coastal waters with nutrients: sea sediments replaced in suspension by agitation, and the flowing back of the

water after having swept through the land. If the coastal waters don’t suffer a poor nutrient level in spring (due to numerous rivers

input), the arrival of unusual substances, mainly organic, as well as a disequilibrium between nutrients by the submersion due to Xynthia, have likely contributed to the appearance of P.australis. The S-N gradient of abundance of this species can be related to the area of submerged land (about 30.000 ha) more important to the north of the study area (fig.1). P.australis

can use organic or mineral nitrogen indifferently, the first one increasing its toxicity

(2).

Many authors (in 3) put forward a recognized connection between anthropic

eutrophisation

and increase in toxic algae bloom. The event here-described corresponds to a sudden short and huge eutrophication.

The Xynthia

storm

can

be

compared

(at smaller scale) with

Hurricane Katrina

(August 2005), particularly

through

the flooding

effect, which

has been followed

by a lengthy

period

of ASP toxicity

in numerous marine animals (4).

Tab.1 Other

shellfish

:

0,E+00

2,E+05

4,E+05

6,E+05

w6 w8w10

w12w14 w16

w18w20

Time (weeks 2010)

Pse

ud

o-N

cel

ls.L

-1

0

50

100

150

200

DA

mg

.kg

-1

Xynthia

20

0,E+00

2,E+05

4,E+05

6,E+05

w6 w8w10 w12 w14 w16 w18 w20

Time (weeks 2010)

Pse

ud

o-N

cel

ls.L

-1

0

50

100

150

200

DA

mg

.kg

-1

Xynthia

20

Fig.3a P. australis

occurrence (histogramm) and mussels

toxicity

(Domoïc

Acid

level

) in Pertuis Breton

since

Feb

8 (w6) to May 27 (w21) 2010.

Fig. 3b

P. australis

occurrence (histogramm) and oysters

toxicity

(Domoïc

Acid

level

) in Pertuis de Maumusson

since

Feb

8 (w6) to May 27 (w21) 2010.

march

x1-x5

<x1

Site Taxa (1 ind.)

Organ D.A. (mg.kg-1)

NO Oléron Isle Cancer pagurus 1 DG 5.3

M <0.15

NO Oléron Isle Cancer pagurus 2 DG 17.1

M <0.15

NO Oléron Isle Necora puber 1 DG 56.2

M <0.15

NO Oléron Isle Necora puber 2 DG 222.4

M 1.4

NO Oléron Isle Necora puber 3 DG 6.8

M <0.15

Sampling date : 29/03/2010 DG = digestive gland, M = muscle

Tab.2 Crustacea

:

References

:1. Nézan

E. et al

2010, Harmful

Algae

News, 41: 1-22. Cochlan

W.P. et al

2008, Harmful

Algae

8: 111-1183. Heisler

J. et al

2008, Harmful

Algae

8: 3-134. Vail

V. (2005), in

Lampl

L.L. and Ayres

D. 2006 (p. 8), Harmful

Algal Research

and Response

: a human

dimensions strategy

(Bauer M. ed), 72 p

Acknowledgements

: We

thank

our

colleagues

J. Grizon, J.L. Seugnet, J.C. Piquet, C. Lecadet, M. Noyer, D. Morin, O. Courtois, P. Geairon, S. Robert and C. Arnaud for providing

field

samples. We

thank

Europ (Feder) and Poitou-

Charentes Region

for financial

contribution.

1

= health

threshold(20 mg.kg-1

Domoïc

Acid)

Legend

may

may

Two

examples

of P. australis

occurrence and tocicity

in reared

shellfish

Fig.2 Pseudo-nitzschia

occurrences in Pertuis Charentais. Maximum monthly

quantity

(MMQ) 2010 compared

with

maximum monthly

quantity

1998-2009Fig.1 Pertuis Charentais and flooding

after

Xynthia

storm

MMQ 1998-

2009

MMQ 2010

Zone inondée le 2 mars 2010

Zone inondée le 4 mars 2010

Carte produite le 5 mars 2010 par le SERTIT

©

SERTIT 2010

Zone inondée le 2 mars 2010

Zone inondée le 4 mars 2010

Zone inondée le 2 mars 2010

Carte produite le 5 mars 2010 par le SERTIT

©

SERTIT 2010

Zone inondée le 4 mars 2010

Zone inondée le 2 mars 2010

Carte produite le 5 mars 2010 par le SERTIT

©

SERTIT 2010

Zone inondée le 4 mars 2010

Zone inondée le 2 mars 2010

Carte produite le 6 mars 2010 par le SERTIT

©

SERTIT 2010

Surface en eau

Terrain fortement humide

Pertuis Breton

Pertuis d’Antioche

Pertuis de Maumusson

Site Taxa (min 10 ind.)

Sampling date

D.A. (mg.kg-1)

Pertuis Breton Pecten maximus 18/02/2010* <0.15

Pertuis Breton Pecten maximus 22/04/2010 162.8

Pertuis d’Antioche Pecten maximus 22/04/2010 208.7

Pertuis Breton Chlamys varia 17/02/2010* <0.15

Pertuis Breton Chlamys varia 22/04/2010 <0.15

Pertuis Breton Chlamys opercularis 22/04/2010 15.9

Pertuis d’Antioche Chlamys opercularis 22/04/2010 27.2 * Before P. australis occurrence

In homage

to Patrick Gentien, colleague

and friend, died

in may

2010

ICES Annual

Science Conference, Nantes (France) 20-24 september

2010