ZOOPLANKTON AS A POLLUTION MONITOR IN A COASTAL MARINE ENVIRONMENT
(TOULON BAY, FRANCE)
Radin F.
1 *
, Richard S.
2
, Jamet J.L.
2
and B. Pavoni
1
1
Dipartimento di Scienze Ambientali, Università Cà Foscari di Venezia, Venezia, Italia
2
Université de Toulon et du Var, Equipe de Biologie des Milieux Aquatiques EBMA, Laboratoire PROTEE, La Garde, France
Abstract
Polychlorinated Biphenyls (PCBs), Organochlorine Pesticides and Polycyclic Aromatic Hydrocarbons (PAHs), were measured in samples
of zooplankton collected in spring-summer 2002 in two separate areas of Toulon Bay, Petite Rade and Grande Rade. Abundance and
diversity of zooplankton community were also evaluated. Zooplankton samples from the more polluted Petite Rade, had significantly
higher PCB concentrations than those of Grande Rade. Moreover, compared to Grande Rade, Petite Rade had lower diversity and evenness
indices, and higher dominance index due to a single species (Oithona nana). PCB pollution can be regarded as a probable factor causing
stress to the Petite Rade’s zooplankton organisms.
Key words: zooplankton, bioaccumulation, PAH, PCB, organochlorine pesticides, biodiversity
Rapp. Comm. int. Mer Médit., 37,2004
540
In zooplankton samples collected between May and July 2002in
the Toulon Bay the concentrations of Polychlorinated Biphenyls,
Organochlorine Pesticides (HCB, DDT, DDD, DDE and HCH) and
Polycyclic Aromatic Hydrocarbons were determined.
The semivolatile, chemically-stable and lipofilic nature of organo-
chlorine compounds combined to their resistance to biodegradation
and photolysis and the low water solubility and hydrophobic pro-
perties of PAHs, cause these compounds to be accumulated in the ma-
rine organism’s lipid rich tissues. All these compounds are included in
the list of persistent organic pollutants and are of great concern be-
cause of their toxicity and suspected or manifest carcinogenic activity.
Zooplankton and particulate matter represent the organic
contaminants’main route for entering the living matter cycle and the
food webs in the marine environments. Organic compounds adsorb
onto particulate matter and are taken up by smaller organisms because
of their high lipid content and relatively higher biomass in the smaller
sizes (1). Therefore, zooplankton can be used as a monitor of recent
pollutionbecause of its short life-cycle.
Moreover, abundance and diversity of zooplankton communities
can be affected by long term disturbancesdue to anthropogenic
inputs. Arfiet al.(2) reported that some species tend to cluster in
facies characteristic of polluted environments and affected by a low
diversity index. They emphasized that the copepods Acartia clausii,
Oithona nanaand the appendicularian genus of Oikopleuridae were
the most abundant organisms in perturbed ecosystems, because of
their euriecious and tolerant nature.
In this study, chemical and ecological analyses of the zooplancton
community were coupled in order to evaluate interactions between
pollutants’body burden and community structure modifications.
An artificial breakwater divides the Toulon Bay into two different
basins, Petite Rade and Grande Rade, contaminated by different
pollutants’loads.
Zooplankton samples were collected every 1-2 weeks at four
stations, in both Petite Rade (S1, S2), heavily polluted, and Grande
Rade (S3, S4), less affected by human inputs.
The highest abundance of zooplankton was found in Petite Rade,
where human activity is more intense because of the commercial and
military port. The copepod Oithona nanawas the most abundant
species of the overall community in S1 (53-78%) and S2 (11-71%) for
the entire period. Petite Rade had low diversity and evenness indices
and high dominance index due to the single species Oithona nana.
Grande Rade, on the other hand, had low zooplankton abundance
and higher diversity and evenness indices. Dominance index was on
average lower than in Petite Rade and Oithona nanawas not the
dominant species, until the beginning of July, when it represented
72% of the community. This situation was probably due to strong
N/W winds that made waters of the two basins mix together.
Differences in zooplankton communty structure between Petite
Rade and Grande Rade were also described by Jamet et al.(3) and
Richard and Jamet (4).
Chemical analyses were performed on lyophilised plankton
samples using solvent extraction (n-hexane, dichloromethane) clean
up and separation with column chromatography (alumina and silica
gel) and HRGC-LRMS determinations (5).
Results showed no temporal trends for the concentrations of
pollutants.
A significant difference was found between PCBs concentrations in
Grande Rade and Petite Rade where PCBs were significantly higher.
On the other hand, Pesticides and PAHs in zooplankton of Petite Rade
and Grande Rade were not significantly different.
In Petite Rade, PCBs concentrations could be ten times higher in
zooplankton than in sediments (6), whereas concentrations in Grande
Rade’s zooplancton and sediments were similar.
The concentrations of the parent compounds o,p’- and p,p’-DDT in
zooplankton were in most samples below the detection limits, while
the metabolite, p,p’-DDD, was at relatively high levels. A DDT/DDE
ratio lower than 1 and the p,p’-DDD high concentration are probably
the result of a past DDT contamination. Total pesticides
concentrations were much more abundant in zooplankton than in
sediments (6).
PAHs were quite abundant in zooplancton, and concentrations were
similar to those in sediments. Despite the zooplankton ability to
metabolise and excrete PAHs (7), concentrations of these compouds
remained quite high in all cases suggesting a continuous input of these
contaminants into the bay.
Considering that Pesticides and PAHs did not show different
concentrations in Petite Rade and Grande Rade, they were thought to
be hardly responsible for the differences in zooplankton community
structure between the two basins.
Therefore, only the correlation between PCBs concentrations in
zooplankton and some ecological indices was investigated. A negative
correlation between richness, evenness and diversity indices was
found. A positive correlation resulted between dominance index and
PCBs concentrations.
These preliminary results indicate that PCB pollution can be
reasonably considered as a probable factor causing stress to the Petite
Rade’s zooplankton organisms, which suffered a reduced diversity in
response to perturbed environmental conditions (8).
References
1-Hargrave B.T., G.C. Harding, W.P. Vass, P.E. Erickson, B.R. Fowler, V.
Scott, 1992. Organochlorine Pesticides and Polychlorinated Biphenyls in
the Arctic Ocean Food Web. Archives of Environmental Contamination
and Toxicology,22: 41-54.
2-ArfiR., G. Champalbert, G. Patriti, 1981. Système planctonique et
pollution urbaine: un aspect des population zooplanctoniques. Marine
Biology, 61: 133-141.
3-Jamet J.L., G. Bogè, S. Richard, C. Geneys, D. Jamet, 2001. The
zooplankton community in bays of Toulon area (Northwest Mediterranean
Sea, France). Hydrobiologia,457: 155-165.
4-Richard S. and Jamet J.L., 2001. An unusual distribution of Oithona
nanaGiesbrecht (1892) (crustacea: cyclopoida) in a bay: the case of
Toulon bay (France, Mediterranean Sea). Journal of Coastal Research,
17(4) : 957-963.
5-Pavoni B., Caliceti M., Sperni L., Sfriso A. Organic micropollutants
(PAHs, PCBs, Pesticides) in seaweeds of the lagoon of Venice. Oceanol.
Acta(in press).
6-RNO 1998. Surveillance du Milieu Marin. Travaux du RNO. Edition
1998. Ifremer et Ministère de l’Aménagement du Territoire et de
l’Environnement.
7-Neff J.M., 1979. Polycyclic Aromatic Hyrocarbons in the Aquatic
Enironment. Sources, Fates and Biological Effects. Applied Science
Publishers Ltd.
8-Odum E.P., 1983. Basic Ecology. CBS College Publishing.
