Wiem BOUSSELLAA, Hela DERBEL, NEIFAR L.
Laboratoire de Biodiversité et Ecosystèmes Aquatiques, Département des Sciences de la
vie, Faculté des Sciences de Sfax, BP 1171, 3000 Sfax, Tunisie.
E-mail: wiem.boussellaa@hotmail.com
LESSEPSIAN MIGRATION AND PARASITISM: ATYPICAL
HISTORY OF INTRODUCTION
Abstract
Parasites can play various roles in the invasion of species, but these are still understudied in
marine ecosystems. In this study, we investigated the role of Lessepsian fish parasites in the
Mediterranean Sea. Prevalence, intensity and richness of parasite communities of exotic
(Siganus rivulatus, S. luridus, Sphyraena chrysotaenia, Fistularia commersonii, Etrumeus
golanii) and native fish (Sarpa salpa, Sparisoma cretense, Sphyraena sphyraena) were
compared taking into account both, Mediterranean and Red Sea populations. Comparative
approaches using GLM and multivariate analyses were used. The parasite examination of
Sphyraenidae revealed the loss of two parasites, the co-introduction of three parasites and the
acquisition of six parasites after the introduction. Parasite richness, prevalence and intensity
were overall much lower in the invasive fish compared to the native ones. The parasite study of
herbivorous fish, two exotic (S. rivulatus and S. luridus) and two native (S. cretense and S.
salpa), revealed the absence of Digenea switching. The parasite investigation of S. rivulatus
and S. luridus in the Mediterranean and Red Sea suggested the loss of 20 parasites in both fish,
three parasites were co-introduced by S. rivulatus and five by S. luridus and four parasites were
acquired by the two fish after their introduction in the Mediterranean Sea. A similarity of
infecti.on levels in native and introduced ranges was found. Parasite diversity of F.
commersonii in Mediterranean and Red Sea showed the loss of at least four parasites, the cointroduction of six parasites and the acquisition of nineteen native parasites. However, parasite
richness, prevalence and intensity were overall much higher in the introduced range compared
to the native one. Finally, for Etrumeus golanii the occurrence of three parasites was
documented. Overall, these results illustrate the co-introduction history of invasive fish and
their parasites into the Mediterranean is not typical but depends on the host invasion history.
Key-words: Lessepsian migration, fish, parasite spillover/spillback, Mediterranean Sea
Introduction
Parasites can play various roles in the invasion of non-native species, but these are still
understudied in marine ecosystems. This also applies to Red Sea species that enter the
Mediterranean Sea via the Suez Canal, the so-called Lessepsian immigrants. In this
study, we investigated the parasites of a number of Lessepsian fishes. The objective of
this work is to provide new information on the parasitofauna of these species and
contribute to the understanding of host-parasite interactions and their ecological and
evolutionary implications in marine ecosystems. More specifically, this research aimed
to test the following three hypotheses: (i) loss of parasites during the process of
introduction of exotic fish in the Mediterranean ("Enemy Release Hypothesis "); (ii)
increased parasitism in native fish populations, through the introduction of exotic
parasites ("spill-over" hypothesis) or the amplification of local parasites ("spill-back"
hypothesis).
2nd Mediterranean Symposium on the Non-Indigenous Species (Genoa, Italy, 22-23 September 2022)
23
Laboratoire de Biodiversité et Ecosystèmes Aquatiques, Département des Sciences de la
vie, Faculté des Sciences de Sfax, BP 1171, 3000 Sfax, Tunisie.
E-mail: wiem.boussellaa@hotmail.com
LESSEPSIAN MIGRATION AND PARASITISM: ATYPICAL
HISTORY OF INTRODUCTION
Abstract
Parasites can play various roles in the invasion of species, but these are still understudied in
marine ecosystems. In this study, we investigated the role of Lessepsian fish parasites in the
Mediterranean Sea. Prevalence, intensity and richness of parasite communities of exotic
(Siganus rivulatus, S. luridus, Sphyraena chrysotaenia, Fistularia commersonii, Etrumeus
golanii) and native fish (Sarpa salpa, Sparisoma cretense, Sphyraena sphyraena) were
compared taking into account both, Mediterranean and Red Sea populations. Comparative
approaches using GLM and multivariate analyses were used. The parasite examination of
Sphyraenidae revealed the loss of two parasites, the co-introduction of three parasites and the
acquisition of six parasites after the introduction. Parasite richness, prevalence and intensity
were overall much lower in the invasive fish compared to the native ones. The parasite study of
herbivorous fish, two exotic (S. rivulatus and S. luridus) and two native (S. cretense and S.
salpa), revealed the absence of Digenea switching. The parasite investigation of S. rivulatus
and S. luridus in the Mediterranean and Red Sea suggested the loss of 20 parasites in both fish,
three parasites were co-introduced by S. rivulatus and five by S. luridus and four parasites were
acquired by the two fish after their introduction in the Mediterranean Sea. A similarity of
infecti.on levels in native and introduced ranges was found. Parasite diversity of F.
commersonii in Mediterranean and Red Sea showed the loss of at least four parasites, the cointroduction of six parasites and the acquisition of nineteen native parasites. However, parasite
richness, prevalence and intensity were overall much higher in the introduced range compared
to the native one. Finally, for Etrumeus golanii the occurrence of three parasites was
documented. Overall, these results illustrate the co-introduction history of invasive fish and
their parasites into the Mediterranean is not typical but depends on the host invasion history.
Key-words: Lessepsian migration, fish, parasite spillover/spillback, Mediterranean Sea
Introduction
Parasites can play various roles in the invasion of non-native species, but these are still
understudied in marine ecosystems. This also applies to Red Sea species that enter the
Mediterranean Sea via the Suez Canal, the so-called Lessepsian immigrants. In this
study, we investigated the parasites of a number of Lessepsian fishes. The objective of
this work is to provide new information on the parasitofauna of these species and
contribute to the understanding of host-parasite interactions and their ecological and
evolutionary implications in marine ecosystems. More specifically, this research aimed
to test the following three hypotheses: (i) loss of parasites during the process of
introduction of exotic fish in the Mediterranean ("Enemy Release Hypothesis "); (ii)
increased parasitism in native fish populations, through the introduction of exotic
parasites ("spill-over" hypothesis) or the amplification of local parasites ("spill-back"
hypothesis).
2nd Mediterranean Symposium on the Non-Indigenous Species (Genoa, Italy, 22-23 September 2022)
23