Tab.3 Parasite biodiversity of fish hosts studied in the Red Sea
Parasite
taxa
Acanthoceph
ala
Copepo
da
Digenea
Monogenea
Nematoda
Tot N
of
speci
es
Siganus
rivulatus
Sclerocollum
rubrimaris
-
Hexangium
sigani
Glyphidohap
tor
plectocirra
-
4
Polylabris
mamaevi
Siganus
luridus
-
-
Gyliauchen
volubilis
Glyphidohap
tor
plectocirra
Procamallan
us elatensis
4
Polylabris
mamaevi
Fistularia
commerso
nii
Sclerocollum
sp.
Caligus
fistularia
e
Allolepidapedon
petimba
-
-
4
Neoallolepidape
don hawaiiense
Etrumeus
golanii
0
0
0
0
0
0
Discussion and conclusions
The parasite diversity in the exotic-parasite fish models revealed the non-uniformity of
the infection parameters of host species examined. These results would suggest that
Lessepsian migration affected native fish hosts by potentially altering the dynamics of
native and invasive parasite-host interactions. In addition, the lower infection levels in
the invasive fish may result in a competitive advantage over native fish hosts (enemy
release hypothesis). Comparison of herbivores fish Digenea indicate that spill-back and
spill-over of parasites are long processes.
The decrease in genetic diversity of the Mediterranean populations of both Siganidae
and the absence of bottlenecks could explain the successful introduction of Monogenea
and reflect a common history of high propagule pressure during initial colonization.
However, the F. commersonii results strongly contradicted the enemy release
hypothesis.
This study identified at least 18 co-introduced exotic parasites associated to invasive
hosts in the Mediterranean Sea. Differences among the studied species suggested that
the history of introduction of invasive parasites into the Mediterranean does not follow a
general pattern and probably depends on the introduced host invasion history as well as
other ecological, physiological and behavioral parameters that influence introduction
success. Indeed, after its initial dispersal, naturally or by introduction, a parasite must
colonize the host population in the new habitat by establishing new infestations.
However, colonization is only possible if the requirements for biotic and abiotic factors
are present. Abiotic factors may include, for example, salinity (Poulin et al., 2011a) or
pH (Marcogliese & Cone, 1996), i.e., factors that can directly affect living stages and
ectoparasites. Another important biotic factor, in addition to suitable host fish, is the
presence of intermediate or final hosts required for a specific parasite to complete its life
cycle. In more global context, the study of parasite communities of exotic fishes has
highlighted the non-uniformity of infestation parameters observed during invasions
2nd Mediterranean Symposium on the Non-Indigenous Species (Genoa, Italy, 22-23 September 2022)
27
Parasite
taxa
Acanthoceph
ala
Copepo
da
Digenea
Monogenea
Nematoda
Tot N
of
speci
es
Siganus
rivulatus
Sclerocollum
rubrimaris
-
Hexangium
sigani
Glyphidohap
tor
plectocirra
-
4
Polylabris
mamaevi
Siganus
luridus
-
-
Gyliauchen
volubilis
Glyphidohap
tor
plectocirra
Procamallan
us elatensis
4
Polylabris
mamaevi
Fistularia
commerso
nii
Sclerocollum
sp.
Caligus
fistularia
e
Allolepidapedon
petimba
-
-
4
Neoallolepidape
don hawaiiense
Etrumeus
golanii
0
0
0
0
0
0
Discussion and conclusions
The parasite diversity in the exotic-parasite fish models revealed the non-uniformity of
the infection parameters of host species examined. These results would suggest that
Lessepsian migration affected native fish hosts by potentially altering the dynamics of
native and invasive parasite-host interactions. In addition, the lower infection levels in
the invasive fish may result in a competitive advantage over native fish hosts (enemy
release hypothesis). Comparison of herbivores fish Digenea indicate that spill-back and
spill-over of parasites are long processes.
The decrease in genetic diversity of the Mediterranean populations of both Siganidae
and the absence of bottlenecks could explain the successful introduction of Monogenea
and reflect a common history of high propagule pressure during initial colonization.
However, the F. commersonii results strongly contradicted the enemy release
hypothesis.
This study identified at least 18 co-introduced exotic parasites associated to invasive
hosts in the Mediterranean Sea. Differences among the studied species suggested that
the history of introduction of invasive parasites into the Mediterranean does not follow a
general pattern and probably depends on the introduced host invasion history as well as
other ecological, physiological and behavioral parameters that influence introduction
success. Indeed, after its initial dispersal, naturally or by introduction, a parasite must
colonize the host population in the new habitat by establishing new infestations.
However, colonization is only possible if the requirements for biotic and abiotic factors
are present. Abiotic factors may include, for example, salinity (Poulin et al., 2011a) or
pH (Marcogliese & Cone, 1996), i.e., factors that can directly affect living stages and
ectoparasites. Another important biotic factor, in addition to suitable host fish, is the
presence of intermediate or final hosts required for a specific parasite to complete its life
cycle. In more global context, the study of parasite communities of exotic fishes has
highlighted the non-uniformity of infestation parameters observed during invasions
2nd Mediterranean Symposium on the Non-Indigenous Species (Genoa, Italy, 22-23 September 2022)
27