International Journal of Mediterranean Ecology - Ecologia ...

SIDI MOHAMMED GHOMARI, GHALEM SELSELET-ATTOU, FRANCISCO HONTORIA, MOHAMMED MONCEF, FRANCISCO AMAT
30
During the last decades great efforts have been
made in this regard, especially in countries such
as Algeria, Morocco and Tunisia, where we have
verified the existence of a pattern of biodiversity
similar to that described in the European
Western Mediterranean, represented mainly by
three common forms: the sexual species Artemia
salina (Leach 1758) and the two parthenogenetic
strains (A. parthenogenetica Barigozzi,
1980): diploid and tetraploid. Furthermore, the
exclusive use of cysts of the species from America
A. franciscana (Kellogg 1906) in marine
aquaculture and its commercial generalization,
has conducted to the introduction of this exotic
species in the Mediterranean basin, taking the
profile of an invasive species, and leading to the
elimination of native strains by a simple competition
phenomenon. This potential threat on
the diversity of the genus can also affect the
North African countries today, where we have
verified the presence of some populations of
the American species in Morocco, and in Tunisia.
Abridged english version
The great diversity of climatic, geological and
hydrological conditions present in the northern
part of the African continent has allowed
the identification of a wide range of hypersaline
ecosystems of the type Sebkha and
Chott (Glossaire in Davis & Gasse 1988).
They show a high productivity, but low biodiversity,
with ecosystems composed mainly of
aquatic invertebrate populations with the presence
of populations of the crustacean Artemia
characteristic of hypersaline environments.
It is well known that the crustacean Artemia
(Branchiopoda, Anostraca) has evolved in
very specific habitats, namely the hypersaline
environments. It is very useful as a source of
food, as live prey for larvae of marine species.
Consequently, it has a high commercial interest
for aquaculture. The genus Artemia is cosmopolitan
and their species show a wide geographical
distribution. It is represented by
sexual species and parthenogenetic strains
spread throughout the world except Antarctica
(Persoone & Sorgeloos 1980; Vanhaecke
et al. 1987; Triantaphyllidis et al. 1998; Van
Stappen 2002; Muñoz 2009). Artemia populations
were reported for the first time in
North Africa by Blanchard and Richard
(1890) by Gauthier (1928) in Algeria (see
Samraoui et al. 2006) and by Gauthier (1929)
and Stella (1933) in Morocco (see Thiery
1989). However, reports on systematic geographical
distribution of Artemia populations
have their origins in the work of Persoone and
Sorgeloos (1980). These authors identified a
list of sites in North Africa, where they mention
the presence of populations of this crustacean,
but no assessment of the species found
was included. Subsequently Vanhaecke et al.
(1987) and Triantaphyllidis et al. (1998) presented
a new distribution, identifying additional
new sites. In this distribution appears
the first initiative to make a distinction
between the sexual populations (Artemia
salina) and the parthenogenetic forms.
During the last decade, great interest has been
focused on global biogeography of Artemia.
Van Stappen (2002), Kaiser et al. (2006) and
Muñoz (2009) have reported new sites for the
countries of North Africa, but in most cases
the distribution is dominated by the sexual
species A. salina.
Populations from Algeria, Morocco and
Tunisia compared to those from the Mediterranean
studied by Hontoria & Amat (1992),
Amat et al. (1995), and Amat et al. (2007)
show a pattern biodiversity similar to that
described in the Western Mediterranean, represented
mainly by three common forms: the
sexual species Artemia salina and the two
parthenogenetic strains (A. parthenogenetica):
diploid and tetraploid. Therefore, we can consider
that the biodiversity of populations of
Artemia in these countries is similar to that
found in the rest of the Western Mediterranean
countries. In Tunisia the presence of a
tetraploid parthenogenetic population in the
Tunisian saline Tunisian of Sijoumi is surprising,
since it has not been cited in previous
studies, as those by Ben Naceur et al. (2009).
They only mention in this saltern the exclusive
presence of the sexual species (Table 1).
It has been also shown that there is a frequent
co-occurrence of A. salina and parthenogenetic
diploid populations in different salt
marshes, with a well marked seasonal alternation.
Sexual species show a preference for
low temperature and dominate during the
winter and early spring, but the parthenogenetic
diploid strains increase their populations
during the spring and summer (Amat
1981). This situation has been confirmed for
the populations from Northern Africa.
The distribution of tetraploid parthenogenetic
populations is particular. In the Iberian Peninsula,
they are distributed mainly in the inland
habitats as they are not usually present in the
coastal salt marshes and salterns. The data
obtained in our case do not coincide with this
pattern.
ecologia mediterranea – Vol. 38 (1) – 2012