Aquaculture Research, 2006, 37, 1050^1052
doi:10.1111/j.1365-2109.2006.01508.x
SHORT COMMUNICATION Hermaphrodite thinlip mullet Liza ramada (Risso, 1810) (Teleostei: Mugilidae) from Homa Lagoon (Izmir Bay-Aegean Sea) Bahar Bayhan & Deniz Acarli Department of Hydrobiology, Faculty of Fisheries, Ege University Izmir, Turkey
Correspondence: D Acarli, Department of Fisheries, Faculty of Fisheries, Ege University, 35100 Bornova, Izmir, Turkey. E-mail: bahar.
[email protected]
Introduction Lagoons are regions to which ¢sh migrate in groups during certain periods of the year. Lagoons cover15% of the coastal regions worldwide, and the most productive ones are located in the Mediterranean region. Eighty to one-hundred active lagoons of di¡erent sizes are known to be located mostly in Italy, Turkey and Greece, but also in Spain, Morocco, Algeria and Egypt (Ravagnan1978). Catadromous ¢sh are usually found in coastal regions of tropical and subtropical zones in large herds and they are presented with 13 genera and approximately 70 species all over the seas of the world. Eight species belonging to the genera Chelon, Liza, Mugil and Oedalechilus are known to be found in the seas of Turkey (Bilecenoglu, TaSkavak, Mater & Kaya 2002). The main mullet species caught in Homa Lagoon are as follows: Thicklip grey mullet Chelon labrosus (Risso, 1827), Golden grey mullet Liza aurata (Risso, 1810),Thinlip mullet Liza ramada (Risso, 1810), Leaping mullet Liza saliens (Risso, 1810), Flathead mullet Mugil cephalus (Linnaeus, 1758) and Soiuy mullet Mugil soiuy (Basilewsky, 1855). Annual ¢sh production in our study region (Homa Lagoon) is 16585.84 kg, 85% of which is composed of mullet species. The main purpose of this study is to present an unusual observation of a hermaphrodite specimen of L. ramada, which is one of the mullet species whose £esh and caviar is consumed as a basic food in the area. Materials and methods The study area, Homa Lagoon, is located in Izmir Bay (38133 028 0 0 N^26150 042 0 0 E), which is an important
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¢shing zone of the Aegean Sea (Fig. 1). The lagoon is 7.4 km long and 3 km wide, with a total area of 1800 ha, having a depth of less than 1m. Some of the physicochemical parameters measured in the Homa Lagoon in the sampling period are as follows: dissolved oxygen: 9.0 mg L 1, salinity: 33.40%, pH: 8.45 and temperature: 23 1C. Results The measured length and weight values of thinlip mullets caught in the study ¢eld on 26 November 2005 by means of a multi£ament ¢shing net with a 32 mm mesh size were, respectively, 33.2 cm (TL), 30.2 cm (FL), 27.8 cm (SL) and 328.57 g (Fig. 2). The weight of the hermaphrodite gonad was 7.55 g (Fig.3). Discussion Homa Lagoon is a region where fresh and marine water input occurs, pollutants and domestic waste enter and where bad weather conditions are frequently seen (Emiroglu, Alpbaz, Elbek,Tolon, Saygi & Cihangir 2001). It is located both near the most important industrialization centre of the Aegean Region and the area in which arti¢cial compost and pesticide are commonly used to increase agricultural production. According to the results of research carried out in the ¢eld, it is emphasized that pesticides are not very harmful to the organisms inhabiting the Gediz delta wetland, but also stating that their use should be re-considered due to the possible effects of these compounds in the future. According to
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Aquaculture Research, 2006, 37, 1050^1052
Hermaphrodite thinlip mullet Liza ramada B Bayhan & D Acarli
Figure 1 Research area.
Figure 2 Thinlip mullet Liza ramada (Risso,1826).
Figure 3 Hermaphrodite gonad of thinlip mullet Liza ramada.
the same study, Gediz River confers a certain amount of organic material and microbiological pollution to Izmir Bay. So, the water quality of the area that is under threat of dense pollution should be monitored systematically (Anonymous 1999). Considerable amounts of chemical material pollutes the environment due to the acceleration of industrialization. Xeno-hormones or endocrine corrosives (EDCs) are the environmental hormones that have an especially destructive e¡ect on the endocrine system of the living organisms and destroy hormonal balance. They a¡ect hormonal functions, and development and reproduction of the living organisms (Arslan 2005). As a consequence of scienti¢c research, these chemicals responsible for endocrine destruction were reported to be a long-term threat for biological diversity and human beings (Alleva, Brock, Brouwe, Colborn, Fossi, Gray, Guillette, Hauser, Leatherland, Mclusky, Muti,
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Hermaphrodite thinlip mullet Liza ramada B Bayhan & D Acarli
Palanza, Porter¢eld, Santti, Stein, Vom Saal & Weiss 1995). It is also stated that when the ¢sh are exposed to environmental oestrogen, it gives rise to a decrease in fertilization or egg production, reduction in gonads (Jobling, Sheadan, Osborne, Matthiessen & Sumpter 1996; Ash¢eld, Pottinger & Sumpter 1998), decrease in sperm number of male specimens and increase in hermaphroditism (Gimeno, Komen, Jobling, Sumpter & Bowner 1998; Nimrod & Benson 1998). As mullets are taken into consideration, due to the fact that the undi¡erentiated gonad phase is long in juveniles of M. cephalus, this species is reported to possibly present a protandrique hermaphroditism in previous studies, but in research carried out in south Carolina, it is identi¢ed to be a gonochoristic species. However, it was also mentioned that hermaphroditic characteristics can be dysfunctional in di¡erentiated mature gonads (McDonough, Roumillat & Wenner 2005). Nevertheless, in the biological studies carried out in Turkish seas with respect to mullets, no hermaphroditic mullet specimen has been reported to date.
References Alleva E., Brock J., Brouwe A., Colborn T., Fossi C., Gray E., Guillette L., Hauser P., Leatherland J., McLusky N., Muti A., Palanza P., Porter¢eld S., Santti R., Stein S.A., vom Saal F. & Weiss B. (1995) Concensus Statement from the work session on environmental endocrine disrupting chemicals: neural, endocrine and behavioral e¡ects, Erice, Sicily. Anonymous. (1999) Sulak alanlar{n y˛netim projesi Gediz deltas{ sulak alan y˛netim plan{ alt projesi. Project no. 97K100020, Final raporu Cilt I, 248pp.
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Arslan C.. (2005) Nonilfenol, oktilfenol ve bisfenol’ˇn deniz kestanesi (Paracentrotus lividus) embriyo geliSimi ˇzerine etkileri. Ege niversitesi Fen Bilimleri Enstitˇsˇ, Doktora Tezi.172pp. Ash¢eld L.A., Pottinger T.G. & Sumpter J.P. (1998) Exposure of female juvenile rainbow trout to alkylphenolic compounds results in modi¢cations to growth and ovosomatic index. Environmental Toxicology and Chemistry 17, 679^686. Bilecenoglu M., TaSkavak E., Mater S. & Kaya M. (2002) Checklist of the marine ¢shes of Turkey. Zootaxa 113, 194pp. Emiroglu D., Alpbaz A., Elbek A.,Tolon T., Saygi H. & Cihangir A. (2001) Ege ve Akdeniz b˛lgesi kyØyyØsal dalyanlaryØn sosyo-ekonomik incelenmesi. Project No. YDABCAG199YO59, 56pp. Gimeno S., Komen H., Jobling S., Sumpter J. & Bowner T. (1998) Demasculasition of sexually mature male common carp, Cyprinus carpio, exposed to 4-tert pentylphenol during spermatogenesis. AquaticToxicology 43, 93^109. Jobling S., Sheadan D., Osborne J.A., Matthiessen P. & Sumpter J.P. (1996) Inhibition of testicular growth in rainbow trout (Oncorhynchus mykiss) exposed to estrogenic alkylphenolic chemicals. EnvironmentalToxicology and Chemistry 15, 194^202. McDonough J.C., Roumillat A.W. & Wenner A.C. (2005) Sexual di¡erentiation and gonad development in striped mullet (Mugil cephalus L.) in south Caroline estuaries. Fishery Bulletin 103, 601^619. Nimrod A.C. & Benson W.H. (1998) Reproduction and development of Japanese medaka folloing an early life stage exposure to xenoestrogens. AquaticToxicology 44, 141^156. Ravagnan G. (1978) Coastal Aquaculture systems for Fish and Crustacea in the Mediterranean. Unep,Vol.15^4, 51pp.
Keywords: Liza ramada, hermaphrodite, homa lagoon, Izmir bay, Aegean Sea
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