e
CM.19921N:6 - Ref.E
Marine Mammals Committee
25
22.5
•
20
~ 17.5
.....
15
12.5
•
Do older cetaceans die from merc1UY contamination1
....
CR. Joiris *, L. HolsbHk *, I. Jansegers **, JM. Bouquegneau **,
U. Siebert * and M. Bossicart *
...
...
a
- l.3b..,raA,IYfi,r Ea,t<Jxkl.,k>gy. ErN (lnip~rsityoIlJru$$t?/s (VlmJ
PJ~i.tJ1aao ~ B-Jt150lJru$$t?Js., Bt9Jgium.
" S~rpk(l 01o..WOI,Jogy,. ll.DiJ'ersity I,f lJeg~ Bt91gium.
In the frame of an interdisciplinary study of seabirds and marine
mammals tound dead (stranded and bycaught) ineluding veterinarian
(anato-pathology, microbiology, parasitology) and ecotoxicologica1 aspects,
we determined the eoneentraion ot stable pollutants - organochlorine
pestlcides, PCBs, heavy metals - in eetaeeans eollected in the North sea, the
Kattegat and the Preneh Attantlc coast. Tbe sampling eoneerned different
t.lssues (musele, liver, kldney and blubber) from 30 eommon dolphins
DeJp1JiJ:tus Mlphis., 17 harbour porpoises PIJ~J18 pIJI?t.~O~ 7 bottle-nose
dolphins Tursiops truocatlJs.. 2 striped dolphins st4o~Da l-~ruJM1J1u.. 1
sperm whale PbySlPtiJr D1aa~p1Ja1us., as well as 6 Norwegian minke wbales
1JaJa~ol'Pt4ra
10 h
..
.!i
"
fi,jris ~t aJ 1
5
2.5
0
0
I
••
•
I
•
3
2
5
4
6
7
9
6
age
10
Figure 1: Relatlonship between total Hg concentratlon in muscle and age
o! harbour porpoises PIJI'>I.';(>(/oa plJl'>I.':l.'>eO.1 trom the North sea and
Kattegat areas.
acuAv(JStrata.
Tbe study ot mercury concentratlons showed an important increase of
total Hg With age (when age data are not yet avallable, the differenee in
concentratlon between juveniles and adults 15 highly significant)(fig. 1);
organie (methyl) Hg was increasing as well, but at a much lower rate. As a
consequenee, the ratlo MeHg to LHg O.e. IMeHg) was strongly decreasing
With increasing LHg level, and thus With age (fig. 2), providing a
confirmatlon of the existenee ot a slow mineralization process in small
cetaeeans (Koeman ,pt aJ.., 1973; !hibaud and Duguy, 1973; capelli ~t aJ..•
1989; Joir15 ~t aJ., 1991, 1992).
!his resulted, for older adults, in very high coneentratlons of inorganic Hg
in the liver and 4 tlmes higher liver to muscle and liver to kldney ratlos for
adults than tor juveniles. In the cast ot the harbour porpoise, the level ot
detoxiticatlon was also det.ermined: about 501 of the inorganie Hg in the
liver ot the adults were not bound to metallotbioneins nor to selenium. and
were thus potentlally tome.
PCB levels were relatlvely high, as expected, and indicatlons were
collected, retlecting the possible existence ot problems ot high Cd
concentrations, whUe tlle other heavy metals did not seem to retlect the
exlstence of any harmtull ettect (table 1).
10
7.5
120
100
,
!
60
~
60
~
40
'1i
20
emuscle.
~M
Oliver.
~
akldney,
~
k
P
It
~
•
L.
...
~
0
0
&0
•
100
0
0
200
0 0 0
0
300
lIllal Hg
400
500
600
700
Figure 2: Ptrcentage of Methyl mercury (~MeHg) in muscle, liver and
kldney ot eommon dolphins ,D"Jp1l/.Dus d,pJp1Jis strandtd on the French
Atlantle coast, as a tunctlon ot total mercury contaminatlon ijJ.g1 g dry
weight).
Table 1: Synopsis of the data on heavy metals and organochlorlnes levels In harbour porpoises
P!la:ven~ plJaxJen~ from the North Sea lind Kllttegllt arBllS (\.lg / g riw); melln (std dev); n 21.
2
Tissue
muscle
melln
r PCBs
ODE
!Hg
MeHg
~ MeHg
Zn
Pb
Cd
Fe
Cr
Cu
Tl
stdd!v
7.41
0.02
8./8
5.6
6.04
79.3
70.\
0.9
0.23
1105
0.32
6.63
1.55
6
3.39
liver
melln
stdd!v
004
37./
/.55
022
596
03/
3.2
6. 7/
71.66
5.87
44.5
140.7
1.13
0.31
2026
0.29
45.56
0
/44.9
3.69
78.4
2./8
024
1/62
025
73.96
0
kidney
melln
stdd!v
2.98
0
2.64
0
8.96
3.84
60
92.8
0.97
1.81
1061
0.42
15.5
0
8.3/
/8.6
/./7
2. 75
362
0.25
4.74
0.0/
Pinnipeds and cetaceans present the exceptional phenomenon that their
health status, more espectally their reproduction potential, could be actually
!ffected by pollution in nature, like it was the case for raptors in the sixties.
It is generally recognized that the main tllreat is due to high PCBs
concentrations. These effects of PCBs could be at the origin of viral mass
mortalities of marine mammals, by repressing their immunologica1 defense
mechanisms, or on the contrary be a consequence of physiologca1 stress, such
as viral infection or starvation. In tJle frame of both interpretations, PCBs
might anyway hinder the recovery of populations after the occurence of
mass mortallties.
In the frame of a broader study of stable pollutants, ho~ver, it appears
that one should take into account the levels of other residues as ~Il. In our
results, this seems to be the case for Hg and, possibly, for Cd.
Mercury contamination of small cetaceans and its evolution in time could
be interpreted as foUows: they are contaminated by methyl mercury, the
main form of mercury in their food. Most of the mercury is present as MeHg
in juveniles where it is accumulating in lipids. Later on, it is than sloWly
mineralized and remobilized (or first remobilized, as it seems to be the case
for two dolphins from the Tyrrhenian sea (Carlini and Fabbri, 1969), and
then mineratized), and is accumulatlng as inorganic Hg in the liver, where it
reaches very high levels. A detailed study of the speciation of this inorganic
Hg is necessary, in order to detect which proportion is detoxified by
meta11othioneins or selenium, or remains potential1y tonc. So that it does not
seem excluded that not only PCBs, but also inorganic Hg might influence the
health status of older animals.
References.
Andre, J., A. Boudou, F. Ribeyre and M. Bernhard. 1991. Comparative study of
mercury accumulation in dolphins i:rt.mel13 t':t?eruJe..wb4) from French
Atlantic and Mediterranean coasts. Sä. Tt,t31.EtJJ"irt'I1.. 104: 191-209.
Alzieu, C. et R. Duguy. 1979. Teneurs en composes organochlores chez les
cetaces et pinnipedes frequentant les cotes fran~ses. (~~t?/t'. At~t~.
107-120.
capelli, R., R. oe PeUegrini, V. Mingani and R. Pogg!. 1989. Prellminary results
on the prestnce of inorganic, organic mercury and selenium in do1phins
m~.n~1Ja t':l.~.ruJAwlu) from the Ugurian sea. Eurt?p. .Res. Ctft.!tt':tfMS., 3:
19-21.
Carlini, R. and F. Fabbri. 1989. Mercury, methylmercury and se1enium in
Italian stranded odontocetes. EUrt'p. Hes. Ct9t3t'WU1~ 3: 25-28.
Joiris, CR., L. Ho1sbeek, ]M. Bouquegneau and M. Bossicart. 1991. Mercury
contamination of the harbour porpoise PlJt't':t?e03 plJt't':t~J1" and other
cetaceans from the North Sea and tht Kattegat. Wate:. AU, & Siw A'>J1ut...
56: 283-293JolriS, CR., L. Ho1sbeek, U. SIebett, JM. Bouquegneau, M. Bossicart, R. Duguy
and M. Simmonds. 1992. Heavy metals and organochlorines in common
do1phins ~lplJi.lJus d~1plJjs stranded on the French Atlantic coasl Eurt?p.
.Res. Cet~w~ 6. In press.
Koeman, JR., W.SM. Peeters, CRM. Koudstaal-Hol, P.S. Tfioe and lJM. de
Goeij. 1973- NatlJrtf" 245: 365.
Law, RJ., BR. Jones, JR. Baker, S. Ktnnedy, R. MUne and RJ. Morris. 1992. Trac.
metals in the llvers of marine mamma1s from the We1sh coast and the
Irish sea. Mar. A'1Jut.l1U11~t... 24: 163-191.
Thibaud, Y. and R. Duguy. 1973. Teneur en mercure chtz les cetac&s des cot.es
de Franc•. lCES' CM 1973/ N:2. 6 ps.
Wagemann, R. and D.G.C. Mutr. 1964. Concentrations of heavy metals and
organochlorines in marine mammals of northern wat&rs: overview and
evaluation. C.1O. T~:;hJ1. Hep. Fjsh Aquat. .~~.. 1279: 97 pps.