First record of the Indo-Pacific cardinal fish Apogon fasciatus ( White , 1790 ) in the Mediterranean Sea

To date, three alien species of the cardinal fish genus Apogon (Lacépède, 1801) have been reported from the Mediterranean Sea. Here we report the first record of a fourth Indo-Pacific species, A. fasciatus, from the Mediterranean coast of Israel. The invasion, within three years, of three alien cardinal fish species of Indo-Pacific origin of the soft bottom infralittoral in the eastern Mediterranean is discussed.

The Indo-Pacific cardinal fish, Apogon fasciatus (White, 1790), is the fourth species of the genus to have joined the ichthyofauna of the Levantine Sea, eastern Mediterranean.The first alien cardinal fish in the Mediterranean, A. pharaonis Bellotti, 1874, was reported in 1947 (Haas and Steinitz 1947).For nearly six decades, this species remained the sole alien cardinal fish in the Mediterranean.Recently, two additional species were reported: A. queketti Gilchrist, 1903and A. smithi (Kotthaus, 1970), in 2006and 2008 respectively (Eryilmaz and Dalyan, 2006;Golani et al. 2008;Goren et al. 2008).The three newcomers represent an ecologically distinct group of cardinal fishes.Unlike the native Mediterranean A. imberbis (Linaeus, 1758)which inhabits rocky reefs and sea-grass habitats, and A. pharaonis -which inhabits sea grass and algae meadows, as well as soft bottom habitats (Goren et al. 2008), the three newcomer species all occur on bare muddy silt bottoms.
The taxonomic status of A. fasciatus is yet unsettled.Gon and Randall (2003:23) considered A. quadrifasciatus Cuvier, 1828, a valid species, since "live fasciatus differ from quadrifasciatus in having 3 dark stripes on the body".Fraser (2005), who studied numerous specimens, considered A. quadrifasciatus a junior synonym of A. fasciatus.That judgement was accepted by Eschmeyer (2008).We follow the recent nomenclature and use here the name A. fasciatus.
Abbreviations: TAU -fish collection of Tel Aviv University; TL -total length.A brief description of the specimens: An Apogon species with two dark brown stripes on body.The lower stripe runs from snout along mid-body to end of caudal fin.Dark pigmentation on caudal fin.The upper stripe, narrower, runs from above post-temporal bone backward to below posterior end of second dorsal fin, where it become less visible, and continues to the upper origin of caudal fin.A whitish along the base of anal and both dorsal fins.In fully erected second dorsal and anal fins, a reddish stripe with tiny black spots is visible above the bright stripe.Above this, the fin is pinkish-orange with tiny black spots.Pelvic fins bright, with reddish color on membrane between third and fifth rays.Lateral line with pored scales 25-26 and 1-2 scales without pores on base of caudal fin.Median predorsal scales 5, the posterior one enlarged with median notch.First dorsal fin with 7 spines; first spine is very short, its length about one quarter of second spine, which is about one third length of third spine.Third spine is longest in first dorsal fin and very robust.
Second dorsal fin with a spine and 9 rays.Anal fin with 2 spines and 8 rays.Pectoral fin with 15-16 rays.Sixteen developed gill rakers on first gill arch.Two to three large scales on preopercle.Three-four large scales on opercle.Preopercle margin serrated.
Selected proportions are presented in Table 1.Remarks: Apogon fasciatus is distinguished from all other Apogon species in the Mediterranean by its unique color pattern: it lacks any vertical bar on its body and/or black spot proximally on the dorsal and anal fins.In addition, it differs from A. imberbis in having 7 spines on first dorsal fin rather than 6.
Distribution: Indo-West Pacific Ocean, from Fiji and New Caledonia, to the Persian Gulf and the Red Sea (Fraser, 2005).
The finding of three recently arrived cardinal fish species in the eastern Mediterranean is remarkable since, unlike the native A. imberbis and the veteran alien A. pharaonis, which mostly inhabit rocky reefs and sea-grass habitats (Goren et al. 2008), the newcomers have been collected on bare muddy-silt bottoms.This raises the question of the possible ecological impact of these species.Cardinal fish are nocturnal planktivorous predators (Kume 2003;Gon and Randall 2003;Barnett 2006).However, we have yet to determine whether A. fasciatus and the other two cardinal fish feed in the Mediterranean on zooplankton or, rather, have reverted to feeding on zoobenthos, as some other alien planktivores have done (Ogorok 1999;unpublished data).
Although the recent appearance of the three cardinal species in this habitat might be considered a coincidence, we suggest it is more likely that their almost simultaneous appearance is indicative of ecological changes that may be attributed either to a rise in water temperature in the region (EEA 2007) or to unknown biotic and/or anthropogenic factors.We suggest that a possible combination of water warming and massive trawling, together with the increased accessibility of the Mediterranean to Red Sea biota, due to the enlargement of the Suez Canal, constitute a kind of intermediate disturbance (sensu Connell 1978;Dial and Roughgarden 1998) that has led to increased biodiversity in the eastern Mediterranean.