DIET COMPOSITION OF RED BANDFISH , CEPOLA MACROPHTHALMA ( ACTINOPTERY-GII : PERCIFORMES : CEPOLIDAE ) , FROM THE AEGEAN SEA OF TURKEY

Background. The red bandfi sh, Cepola macrophthalma (Linnaeus, 1758), is a benthic fi sh usually not exceeding 450 cm in length. It occurs in the eastern Atlantic from the British Isles to the north of Senegal and is also common throughout the Mediterranean Sea. The red bandfi sh has no commercial value and is often represented in the discarded catch. The knowledge of the feeding ecology, of non-commercial as well as commercial species, is essential for implementing a multispecies approach to fi shery management. Studies on red bandfi sh feeding biology have been rather scarce and the majority of them lacked taxonomical approach. The presently reported study constitutes the fi rst report on the diet of Cepola macrophthalma from two bays on the Turkish coast. Material and methods. The study was based on the specimens of Cepola macrophthalma collected in İzmir Bay and Sığacık Bay from May 2005 to June 2006. The following basic parameters were calculated, based on the data collected during the analysis of red bandfi sh diet: relative number of food items in the gut content, frequency of occurrence, and relative weight of total gut content. Principal food items were determined using the index of relative importance (%IRI). The differences in the diet composition were tested for length groups and seasons by using the Bray–Curtis similarity index for both areas studied. Results. A total of 380 stomachs were examined in two bays. According to the analyses a total of 18 different prey species belonging to nine major systematic groups were found, i.e., Anthomedusae, Siphonophora, Polychaeta, Crustacea, Mollusca, Chaetognatha, Appendicularia, Thaliacea, and Actinopterygii. Concerning overall diet composition, crustaceans (especially copepods) were the most important prey in terms of %IRI, %N, %F, and %W in all seasons. In this study, a total of 80 taxa were found and identifi ed. According to the Bray–Curtis similarity index, the diet of the red bandfi sh was similar within all seasons for both areas. Conclusion. Stomach content analysis of red bandfi sh showed that it is a zooplanktophagous species. In addition to bottom species it feeds also on pelagic organisms. This fact indicates ontogenetically based food preferences of the species.


INTRODUCTION
The red bandfi sh, Cepola macrophthalma (Linnaeus, 1758), is a zooplanktophagous benthic species found solitary or in small groups at depths ranging from 10 to 450 m, with an "optimal depth window" between 60 and 120 m (Stergiou 1993).It occurs in both temperate and subtropical waters and is known to be distributed in the eastern Atlantic from the British Isles to the north of Senegal (Bauchot 1987).It is also common throughout the Mediterranean Sea, as well as in Turkish seas, but not in the Black Sea (Tortonese 1986, Bauchot 1987).The red bandfi sh has economical importance in Spain and Italy (Tortonese 1986, Bauchot 1987), but no commercial value in Turkey (Düzbastılar 2014).
Although biological aspects of the red bandfi sh have been studied by several authors (Atkinson 1976, Martín and Sabatés 1991, Stergiou et al. 1992, 1996, Stergiou 1993, 1999, Stergiou and Papaconstantinou 1993, Vallisneri et al. 2006, Dulčić et al. 2008, Giacalone et al. 2010) in the Mediterranean Sea, a few of them are related to the feeding of red bandfi sh.In the above-mentioned studies prey items were generally not evaluated in relation to the exact specifi c identity or the sampling season.Even though the species is distributed in all Turkish seas except the Black Sea, the relevant studies were scarce and there have only been two reports on its age and growth properties (Kaya et al. 2001, Leblebici unpublished ** ).
The purpose of the presently reported study was to improve the knowledge on the feeding habits of the red bandfi sh by analysing the qualitative and quantitative variations of the food items in the stomach contents according to length groups and according to seasons in two bays of the Aegean Sea.

MATERIAL AND METHODS
Specimens of the red bandfi sh, Cepola macrophthalma (total lengths ranging between 11 and 42.2 cm), were collected by trawl in the İzmir Bay and Sığacık Bay, Turkish Aegean Sea from May 2005 to June 2006 (Fig. 1).The samples were collected seasonally by a research vessel-R/V Egesüf (27 m length, 373 kw) in İzmir Bay and by a commercial trawler-F/V Hapuloğlu (23 m length, 410 kw) in Sığacık Bay.The sampling depth ranged between 45 and 70 m in İzmir Bay, and 145-296 m in Sığacık Bay.The fi sh stomachs were removed immediately after capture and were stored in 4% buffered formalin solution until the contents were analysed.In the laboratory the stomach contents were assigned to groupor species level with a SZX7 Olympus stereo microscope.The identifi cation of digested copepods was done from body part by following the methods of Rose (1933) and Brodskii (1967).Once counted, the individuals of the same species were weighed together (wet weight to the nearest 0.0001 g) after excess moisture was removed by blotting prey items on tissue paper.
For a quantitative description of the diet, Hyslop (1980) equations were used; relative number of total gut content (%N), frequency of occurrence (%F), and relative weight of total gut content (%W).Main food items were determined using the index of relative importance (IRI) (Pinkas et al.1971):

RESULTS
A total of 380 stomachs of red bandfi sh, Cepola macrophthalma, were examined, including 180 from İzmir Bay and 200 from Sığacık Bay.Only 7 stomachs (1.84%)-all of them collected in winter-were empty.According to the analyses a total of 18 different prey species was found belonging to the nine major systematic groups, Anthomedusae, Siphonophora, Polychaeta, Crustacea, Mollusca, Chaetognatha, Appendicularia, Thaliacea, and Actinopterygii.Pelagic copepods (Copepoda) were found to be most important prey group (MIP) in the diet for all length groups and seasons in each bay.Secondary prey groups (SP) were determined as decapod larvae, Appendicularia, Cladocera, Cirripedia larvae, Chaetognatha, and Bivalvia and it has been found that the sequence of their abundance changed by seasons and length groups, whereas Siphonophora, Isopoda, Mysidacea, Amphipoda, and Ostracoda were rare and rated as occasional prey groups (OP) (Tables 1-5).
Considering the overall diet composition, crustaceans (especially copepods) were the most important prey items in terms of %IRI, %N, %F, and %W in all seasons and length groups for each bay The remaining portion of the diet was shared by decapod larvae, Chaetognatha, Appendicularia, Cladocera, Cirripedia larvae, Brachyura larvae, Ostracoda, Mysidacea, Bivalvia, Anthomedusae, Siphonophora, fi sh larvae and eggs, Thaliacea, Polychaeta, Amphipoda, Isopoda, and Gastropoda (Tables 1-4).In the presently reported study, covering all seasons, a total of 80 taxa were determined (Tables 1 and 2).There were 69 taxa in the fi sh from İzmir Bay 69 and 67-from Sığacık Bay.
The diet of red bandfi sh for all seasons was made up mainly of pelagic copepods for both bays as the main food item (Tables 1 and 2).The abundance of pelagic copepod species changed by seasons.In İzmir Bay, the dominant food items were: Oncaea media, Corycaeus typicus, Acartia clausi, and Clausocalanus arcuicornis (in spring); Centropages typicus and Ditrichocorycaeus brehmi (in summer); Ditrichocorycaeus brehmi, Temora stylifera, Oncaea media, and Euterpina acutifrons (in autumn); and Temora stylifera, and Paracalanus parvus (in winter).In Sığacık Bay, the dominant food items were: Corycaeus typicus and Oncaea media (in spring); Centropages typicus, Ditrichocorycaeus brehmi, Corycaeus giesbrechti (in summer); Ditrichocorycaeus brehmi, Paracalanus      parvus (in autumn); and Oncaea media, Temora stylifera, Paracalanus parvus, and Ditrichocorycaeus brehmi (in winter).In each bay, the diet of red bandfi sh for all length groups consisted of pelagic copepods as the main food item.However, the number of the decapods and teleost larvae, which are bigger prey items compared with Copepods, increased slightly along with the increasing size of the bandfi sh increased (Tables 3 and 4).
According to the Bray-Curtis similarity index, the diet composition of the red bandfi sh was similar for seasons in each bay.The similarities were found as 78.89% in summer, 75.93% in autumn, 75.02% in winter, and 70.91% in spring (Fig. 2).In respect of the stomach content analysis, red bandfi sh fed on pelagic planktonic organisms, is a zooplanktophagous species and especially its main food item group was identifi ed as copepods (Tables 1-5).
Čakelić (unpublished * ) conducted a study on the diet of red bandfi sh from Adriatic Sea and reported that the dominant food item in summer were euphausiids, followed by copepods, whereas in all the remaining seasons the principal diet item were copepods.
The presently reported results on the stomach content of red bandfi sh were consistent with the results of the fi ve research projects described above.The only major difference was that in the studies done by Vives et al. (1959), Stergiou (1993), and Čakelić (unpublished * ) copepods were the second dominant food item, whereas in our study pelagic copepods were dominant in all seasons.We believe that the presently reported shift towards copepods might be a result of the presumed abundance of zooplankton off the Turkish coast.This would be consistent with the results of Stergiou (1993), who concluded that, red bandfi sh food preference changes according to the abundance of the plankton rather than the size of planktonic organisms.According to Vives et al. (1959) and Atkinson (1977) there was a relation between the composition of zooplankton found in the stomach contents of the red bandfi sh and the depth they inhabit.
The prey organisms found in the stomach contents of red bandfi sh well refl ect the species composition present at respective depths inhabited/visited by this fi sh (Scotto di Carlo et al. 1984, Weikert andTrinkaus 1990, Sever unpublished ** , Aker unpublished *** ).Stergiou (1993) reported that red bandfi sh hides and rests in the cavities made by it, but subsequently it feeds in the pelagic zone.* Čakelić M. 2014.Sezonska prehrana i dužinsko-maseni odnos mačinca crvenog, Cepola macrophthalma (Linnaeus, 1758) na području južnog Jadrana.[Seasonal nutrition and length-weight relationship for red bandfi sh, Cepola macrophthalma (Linnaeus, 1758)  In our study, the copepods were the dominant group in the stomach content, but this group was represented by meroplanktonic and holoplanktonic organisms.This fact obviously showed that bandfi sh feed in the pelagic zone.
Prey items in the stomach contents represented different taxa, including also rarely consumed prey items, representing Isopoda, Amphipoda, Gastropoda, and Thaliacea.Copepods were the most important prey group of bandfi sh and they were dominant in terms of numbers and frequency in each season and stomach.Copepods were also reported as the dominant group in each season by zooplankton studies from various region of the Aegean Sea (Moraitou-Apostolopoulou 1972, 1976, 1985, Benli et al. 2001, Özel and Aker 2004, İşinibilir 2009, Sever unpublished * , Aker unpublished * ).Exceptionally, cladocerans were dominant group along with copepods in a seasonal and horizontal sampling study by Özel and Aker (2004).Nonetheless, frequency of Cladocera was lower in our study.This fact may be explained that Cladocera species are more abundant in surface waters than they are in the feeding areas of red bandfi sh (Moraitou-Apostolopoulou and Kiortsis 1973).
None of the previously mentioned researchers, studying feeding habits of the red bandfi sh, observed how the prey composition of this fi sh changes along with its length.Our study seems to be fi rst providing such data.We also managed to demonstrate that the red bandfi sh is a zooplanktophagous species.Even though the species lives on the bottom, it prefers to feed on pelagic organisms.This fact indicates ontogenetically based food preferences of the species.

Table 1
Diet composition of red bandfi sh, Cepola macrophthalma, in the İzmir Bay in sampling periods

Table 2
Diet composition of red bandfi sh, Cepola macrophthalma, in the Sığacık Bay in sampling periods

Table 3
Diet composition of red bandfi sh, Cepola macrophthalma, in the İzmir Bay by length groups

Table 4
Diet composition of red bandfi sh, Cepola macrophthalma, in the Sığacık Bay by length groups

Table 5
Preferred prey items of red bandfi sh, Cepola macrophthalma, according to Morato Index S -sampling site; MIS = Morato Index score; MIP = main important prey, SP = secondary prey, OP = occasional prey.