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Öğe CARTILAGINOUS FISHES AND FISHERIES IN THE AEGEAN SEA(Turkish Marine Research Foundation-Tudav, 2015) Yigin, C. Cigdem; İşmen, Ali; Onal, Umur; Arslan, Mukadder[Anstract Not Available]Öğe COMPARISON OF GAMETOGENIC CYCLES OF THE ENDEMIC EUROPEAN CARPET SHELL CLAM (RUDITAPES DECUSSATUS) AND THE INTRODUCED MANILA CLAM (RUDITAPES PHILIPPINARUM) FROM A TEMPERATE COASTAL MEDITERRANEAN LAGOON IN THE DARDANELLES, TURKEY(Natl Shellfisheries Assoc, 2015) Genez, Pinar; Onal, Umur; Gezen, Mehmet R.In this study, the gametogenic cycle of the newly introduced Manila clam Ruditapes philippinarum was described for the first time for Turkish waters and compared with that of the native European grooved carpet shell clam Ruditapes decussatus coexisting in Cardak Lagoon (Canakkale, Turkey) in the Dardanelles. A total of 480 individuals were sampled for each species between January and December 2011. Both species exhibited similar distinct seasonal changes in gonad activity and completed their gametogenic cycles. In both species, gonads advanced very fast after winter reaching ripe stage in April and May in the Manila clams and carpet shell clams, respectively. In Manila clams, spawning commenced in April and continued until October. In carpet shell clams, spawning started in May, but the main spawning event occurred in June and continued until July with a discontinuation in August and a marginal spawning taking place in September and possibly in October. Gonad index (GI) values were indicated similarities in gonad development between males and females of both species with apparent synchronism between sexes during early development, first maturation and early spawning until July. We report for the first time the reproduction of the Manila clam in Turkish waters and show that optimal conditions for gametogenesis and spawning exist for this exotic species from March until October in the Dardanelles. This information will be useful for clam fishery management especially in areas where carpet shell clam and the Manila clam are known to coexist.Öğe Comparison of predicted and measured levels of organic material input from a commercial cage farm in Western Turkey(Western Philippines Univ, 2022) Sepil, Ahmet; Onal, UmurIn this study, two different sediment trap trials were carried out to determine the deposition rate (flux) of particulate organic materials (POM) from marine cage farms. Flux predicted using a commercial software (Meramod), measured almost two-fold higher (1,355.5 g m-2 yr- 1) in 2009 compared to that in 2008 (765.0 g m-2yr-1). Predicted levels of flux were higher than measured values in all trials and ranged between 1,251.6 g m-2 yr-1 in 2008 and 1,811.9 g m-2 yr-1 in 2009. There were also considerable differences in measured and predicted rates of flux at each station. High variations of flux in repeated measures indicated the need for strict control of farm maintenance routines during long-term trap studies. Near bottom current speeds, periodic resuspension events and the presence of wild fish assemblages were considered as major factors that may have effects in predicting the accumulation rates of POM.Öğe DEMERSAL FISHES AND FISHERIES IN THE AEGEAN SEA(Turkish Marine Research Foundation-Tudav, 2015) İşmen, Ali; Tokac, Adnan; Onal, Umur[Anstract Not Available]Öğe Diet Size Preference of Zebrafish (Danio rerio) Larvae Fed on Cross-Linked Protein-Walled Capsules(Mary Ann Liebert, Inc, 2016) Onal, Umur; Langdon, ChrisTo optimize diet particle size for ingestion by zebrafish larvae, Danio rerio, a series of diet selection experiments were carried out using two different length classes: 5-day-old, first feeding larvae with a mean standard length (MLs) of 3.8mm and 15-day-old larvae with MLs of 5.2mm. For this purpose, crosslinked protein-walled capsules with five different size classes (20, 21-45, 46-75, 76-106, and 107-212m) were used in selection experiments. A particle size selection model was then developed after accounting for both rate of loss of capsules in the water column and their ingestion by larvae. Results indicated that concentration of larger particles in the water column decreased rapidly and less than 20% of capsules larger than 75m were available for the larvae after 30min. Zebrafish larvae accepted a wide range of particle sizes, but larvae preferred particles much smaller than the maximum size they could ingest. While first feeding larvae preferred 21-45m capsules, 15-day-old larvae preferred capsules in the 47-75m size range. A better understanding of the behavior of small-sized food particles in the water column and their acquisition by fish larvae is important to optimize feeding protocols in successful larvae culture.Öğe Early Weaning of Discus Symphysodon spp. Larvae: Histological and Morphological Observations(Israeli Journal Of Aquaculture-Bamidgeh, 2011) Celik, Ihsan; Onal, Umur; Cirik, Sukran; Duman, Canan; Ingin, Tuncay; Celik, PinarTo determine the optimal timing for weaning discus (Symphysodon spp.), larvae were fed a control diet of 100% Artemia, or weaned onto a micro-ground diet on day 18, 23, or 28 after hatching, until 45 days after hatching. During the first 14 days, the development of the digestive tract was studied to determine key events in the early ontogeny of discus larvae. There were significant (p<0.05) differences among treatments in the growth of the larvae. The highest weight increase was observed in the control group but good growth was also obtained when the larvae were weaned to dry feed 28 days after hatching. The specific growth rate (SGR) was 6.0 +/- 0.19 in the control group and 0.4 +/- 0.239, 2.0 +/- 0.257, and 5.2 +/- 0.382 in the 18, 23, and 28 day groups, respectively. Mean survival in all treatments was 56.25% with no significant differences among treatments.Öğe ELASMOBRANCHS OF THE SEA OF MARMARA: CATCH, BIODIVERSITY AND CONSERVATION(Turkish Marine Research Foundation-Tudav, 2016) Yigin, C. Cigdem; İşmen, Ali; Onal, Umur; Arslan Ihsanoglu, Mukadder[Anstract Not Available]Öğe Evaulation of anchovy as a feed for turbot (Psetta maeotica)(Ege Univ, 2006) Ergün, Sebahattin; Yigit, Murat; Turker, Ali; Onal, UmurIn this study, the effects of feeding young turbot (Psetta maeotica) with either dry pellet (50% crude protein and 18% crude oil), fresh anchovy (Engraulis encrasicholus; 20.8% crude protein and 9.2% crude oil) or combination of both on growth and feed efficiency rate (FCR) were investigated. A total of 90 turbot fry (15 fish per tank) with a mean of initially weight of 41 g were used. At the end of 45 day, the mean weights of fish with dry pellet (PL), fresh anchovy (HS) or combination of both (HP) were 62,30 +/- 2,22 g, 63,54 +/- 1,89 g and 62,90 +/- 0,89 g, respectively. No significant differences were observed among treatments (P > 0.05). Daily food consumption (g dry feed/g fish weight) and FCR (g dry feed/g weight gain) values for as follows: 0,77 +/- 0,01 ve 0,86 +/- 0,07for PL, 0,78 +/- 0,01 ve 0,82 +/- 0,09 for HP, and 0,75 +/- 0,02 ve 0,79 +/- 0,06 for HS. There were no differences between any treatments (P > 0.05). Our findings indiciated that of feedings turbot with HP, PL and HP had similar effects on growth and FCR. Turbot can be fed either dry pellet or fresh anchovy or combinating of both.Öğe First Record of Armina neapolitana (Delle Chiaje, 1824) (Gastropoda: Heterobranchia) in the Sea of Marmara (Turkey)(Cahiers De Biologie Marine, 2016) Tuncer, Sezginer; Artuz, M. Levent; Onal, UmurIn August 2015, three specimens of Armina neapolitana were collected from a depth of 64 m in the Sea of Marmara, Turkey. This is the first record of Armina neopolitana, a previously unknown species in Turkish waters.Öğe Histological development of digestive tract in discus, Symphysodon spp. larvae(Springer, 2010) Onal, Umur; Celik, Ihsan; Cirik, SuekranThe present study provides information on the histomorphological development of digestive system of discus, Symphyosodon spp., larvae during the first month of life. Discus larvae are altricial at hatching, with an undifferentiated digestive tract and a large yolksac, which is completely consumed within 7 days. The mouth opens 3 days after hatching (DAH) and the larvae starts feeding on AF Artemia at 4 DAH when offered. At 3 DAH the digestive tract is differentiated with distinct esophagus, stomach anlage, and mid- and hindguts. At 5 DAH, discus larvae is an active feeder, equipped with partly developed jaws and ossified gill arches and an inflated swim bladder. The liver and pancreas are present and supranuclear inclusion vacuoles (SIV) appear in the hindgut for the first time. Gastric glands in stomach were first observed 7 DAH and proliferated by 11-13 DAH. SIV were a common feature in the midgut and hindgut epithelium until 15-23 DAH. Therefore, exclusive use of artificial diets should be postponed until 2-3 weeks after hatching.Öğe Potential delivery of water-soluble protein hydrolysates to marine suspension feeders by three different microbound particle types(Elsevier Science Bv, 2009) Onal, Umur; Langdon, ChrisSpray-dried zein particles (SDZP), spray-water zein particles (SWZP) and gelatin-alginate beads (GAB) were prepared containing a defined dietary mixture and their performances were compared for delivering the soluble fraction of protein hydrolysates. Measures of performances of these three different microbound particle (MBP) types included inclusion, encapsulation, retention and delivery efficiencies in addition to T-50 (time to 50% retention) values. SDZP had higher inclusion (IE) and encapsulation efficiencies (EE) compared to those of SWZP and GAB. A maximum IE of 66.60% and EE of 10.01% were achieved for SDZP. Although elimination of water from the manufacture process resulted in significantly higher inclusion and encapsulation efficiencies for SDZP, retention efficiencies and leakage profiles of all particle types were similar and followed a biphasic pattern with an initial burst release followed by a slower phase. Delivery of hydrolysates by SDZP was greater than for other MBP types with fifty percent of the initial hydrolysate retained after 36 min suspension in water. SDZP provides a more effective delivery vehicle for soluble protein hydrolysates than the other MBP types evaluated in this study. This, in turn, may help overcome limitations in the delivery of water-soluble nutrients and formulation of artificial diets for marine fish larvae and other suspension feeders. (C) 2009 Elsevier B.V. All rights reserved.Öğe SHRIMP FISHERIES IN THE SEA OF MARMARA(Turkish Marine Research Foundation-Tudav, 2016) İşmen, Ali; Onal, Umur; Ismen, Pinar; Yigin, Cahide Cigdem; Arslan Ihsanoglu, Mukadder[Anstract Not Available]Öğe The dependence on the use of live feed organisms is a major drawback for the extensive use of microparticulate diets in the mass culture of marine fish larvae(Ege Univ, 2006) Onal, UmurThe major reason for this dependence is the lack of effective microparticulate diets that are comparable to live feed organisms. Major problems associated with artificial larval diets stem from physical characteristics such as size, color, density and hardness of the particles, the acceptability of diets by larvae and their digestibility. Water-soluble nutrients leach out of microbound particles and Cross-Linked Protein-Walled Capsules within couple of minutes. Lipid-Walled Microcapsules, on the other hand, retain water soluble nutrients such as amino acids effectively, but their physical properties are not suitable for larval feeding. The characterization of limitations and potentials of microparticulate diets may help to solve such problems and will be a major footstep towards developing novel microparticulate diets that would support the growth and survival of fish larvae.Öğe The General Profile of Aquarium Sector in Istanbul (Turkey)(Medwell Online, 2010) Celik, Ihsan; Yılmaz, Sevdan; Celik, Pinar; Saygi, Hulya; Onal, Umur; Bashan, TolgaA survey study was conducted in order to put forth the general status of aquarium sector in Istanbul (Turkey). Within the scope of this study, it is found out that 550-600 aquarium makers, 200 of which are registered to a non-governmental organization operate in Istanbul. A great amount as 50.8% of aquarium businesses in Istanbul is sole proprietorships. They work with a strategy of providing the living things (fish, plant, etc.) and materials (heater, filter, pump etc.) which they trade from domestic and foreign sources and transporting them to the customer. The members of Cyprinidae which is among the fish groups that aquarium makers in Istanbul sell at most, rank the first and Cichliade and living thing breeding groups follow them. It is observed that domestic retail sales are mostly done in winter season (90.9%). Additionally, data on issues such as educational status and work experiences of the employees in the sector, working capacities of the businesses, kinds of plant and animal types produced or imported.Öğe The performance of a small-scale, high-density, continuous system for culturing the rotifer Brachionus plicatilis(Tubitak Scientific & Technological Research Council Turkey, 2010) Onal, Umur; Celik, Ihsan; Ergün, SebahattinThe performance of a high-density continuous system was evaluated as an alternative to conventional low-density batch-culture systems for culturing the rotifer Brachionus plicatilis. Rotifer densities ranging from 1700 to 3760 individuals/mL were achieved in 4 different trials that lasted 10-18 days. Problems associated with NH3-N and pH were controlled by increasing the water exchange rate and periodic addition of ammonia remover. While NH3-N and pH values were 0-8.8 mg/L and 6.9-9.3, respectively, the most important problem was the accumulation of TSS at concentrations of up to 85 mL/L within a very short time after start-up. Further studies are required to develop simple and cost-effective filters that reduce TSS concentrations. Use of continuous systems in combination with concentrated algae is potentially an effective alternative to existing batch-culture systems.
