Deniz Teknolojileri Meslek Yüksekokulu Koleksiyonu

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https://hdl.handle.net/20.500.12428/3538

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Assessing Seferihisar-İzmir (Türkiye) geothermal energy prospects through marine seismic and field geology data modelling
(Pergamon-Elsevier Science Ltd, 2025) Kılınç, Gizem; Çifci, Günay; Okay Günaydın, Seda; Hasözbek, Altuğ; Gürçay, Savaş; Güngör, Talip; Demirkiran, Zülfü
Seferihisar (Izmir) is one of the most significant geothermal regions in the Aegean of Western Anatolia, Turkiye, due to its high geothermal gradient, extensive fault systems, and unique interaction between marine and meteoric waters that create distinct geothermal reservoirs. This study evaluates the geothermal potential and geological characteristics of the Seferihisar area by integrating marine seismic data with onshore geological observations. Specifically, this study combines: (i) geological and geochemical data from geothermal wells along the Tuzla Fault, (ii) high-resolution multichannel seismic reflection data from the Sigacik and Kusadasi Bays, and (iii) correlated onshore and offshore geological and geophysical datasets to develop a 2D conceptual cross-section and a 3D fault model. Geochemical analyses, including water geochemistry, XRF, and isotope studies, reveal that geothermal fluids in the region originate from a mix of meteoric and marine sources. Chloride concentrations in geothermal wells reach approximately ranging from 11,692 to 12,000 ppm, confirming significant seawater intrusion, while geothermometers estimate reservoir temperatures in the range of 220-280 degrees C. Isotopic data, such as He-3/He-4 ratios (similar to 0.9 Ra), suggest minor mantle involvement, and Ar-40/Ar-36 ratios ranging 301 that indicate crustal contributions to the geothermal fluids. These isotopic signatures provide critical insights into the sources and circulation dynamics of geothermal systems. Through integrated 2D conceptual cross-sections and 3D fault modeling, the study identifies the marine extension of the Tuzla Fault and its role in fluid dynamics, including up-flow and out-flow processes. The fault's continuities are linked to geothermal gradients and active fluid pathways, making the Tuzla Fault a critical target for geothermal exploration. The harmonized models suggest three potential drilling sites with high thermal gradients and fault-controlled fluid flow, optimizing the exploration strategy. Scaling and corrosion challenges in production wells are addressed through the application of inhibitors, which are integral to ensuring sustainable operation and long-term system performance. These multidisciplinary findings provide likely actionable insights into optimizing resource extraction, reducing environmental impact, and improving the long-term performance of geothermal systems. The study supports sustainable geothermal energy development in the Seferihisar region by addressing production challenges and guiding effective resource management.
Comparative study on ship wave making resistance via viscous and IBEM solvers
(Elsevier Ltd, 2021) Özdemir, Yavuz Hakan; Coşgun, Taner; Barlas, Barış
The present paper concerns the numerical modeling of the free surface flow around the Wigley hull using viscous and potential flow based solvers over a range of Froude Numbers from 0.22 to 0.48. Numerical results of the in-house iterative boundary element method (IBEM) code and unsteady Reynolds Averaged Navier-Stokes (URANS) CFD tool presented in comparison with the range and average of the experimental data from the literature. The study aims to identify the Froude number envelope in which potential and viscous solvers work well, and match the results with the physical behavior of the flow. The results reveal that both methods are capable of predicting the wave-making resistance in satisfactory agreement with the experiments at intermediate Froude Numbers. IBEM exhibits slightly better accuracy at very low operating velocities. When the ship is advancing with a forward speed at Fn > 0.4, boundary layer separation related viscous effects and enhancing turbulence in the wake region of the hull cause the IBEM to underestimate the resistance. For low Fns, the deviation from the mean of the experimental data is 5% and 17% for IBEM and URANS, respectively, while the relative errors are calculated as 7% for URANS and 23% for IBEM at the highest Fn. Similarly, when the Fn reaches up to 0.4, the URANS method predicts higher values of wave climbing near the bow region compared to those of the potential solver, while the computations of both methods are very close at lower Fn. Besides these, IBEM enables a greater saving of computational time while reaching through the lower values of Fn. The findings of the study reveal that the present IBEM approach provides quick and reliable numerical solutions till the effect of viscous stress becomes non-negligible (which is Fn < 0.4 for investigated Wigley case), and up to this range, the accuracy of the method is inversely related to the ship velocity.
Nonlinear roll damping coefficients and natural frequency estimation via augmented extended Kalman filtering for floating body
(Taylor & Francis Ltd, 2024) Özdemir, Yavuz Hakan
The nonlinear roll damping coefficients and natural frequency of a floating body are discussed in this article using an augmented Extended Kalman Filtering (EKF) method. This paper presents a non-linear model-based observer for the combined estimation of free roll decay motion states and damping coefficients. The identification framework uses an improved extended Kalman filter (EKF) to deal with model parameter variability and noisy measurement input. The estimated error was compared to the theoretical results obtained from the covariance matrix for filtering correctness. It is found that the nonlinear damping coefficients and natural frequency obtained from the EKF approach are a more realistic representation of the roll dynamics from the general estimation procedure given by the literature. The proposed method also has the built-in capability to remove random noise from the measured roll. The influence of noise levels in the measurements on the identification accuracy was investigated and discussed.
Physicochemical Characterization of Biomineralized Structures of Sea Pen Pteroeides spinosum (Ellis & Solander, 1786) (Octocorallia: Pennatulidae)
(Springer Int Publ Ag, 2025) Erdoğan, Sevil; Özalp, Hasan Barış; Taşdelen, Betül
In this study, biomineralized polyp leaf spicules and the endoskeletal axis of the coral Pteroeides spinosum were physicochemically characterized by FTIR, SEM, EDX, TGA, XRD, ICP-MS, and ICP-OES analyses. The mineralized inner axis and polyp leaf spicules of P. spinosum were also pulverized and incorporated into the polyacrylamide (PAAm) hydrogel structure. In vitro bioactivity of coral polyp leaf spicules was evaluated by using simulated body fluid. Characterization analyses identified the major crystalline phase of coral polyp leaves spicules and the inner axis as calcite. The coral's inner axis exhibits a notched and perforated surface morphology. Calcite sclerites obtained from polyp leaves exhibit a crystalline structure and smooth surface morphology. TGA results revealed the organic matter in the coral individual is higher than that of the polyp leaf spicules. It resulted the coral's inner axis was compatible with the PAAm hydrogel. Coral polyp leaf spicules did not form apatite on their surface in simulated body fluid. The calcite content of the coral P. spinosum can be evaluated as an inert additive to improve mechanical properties and thermal stability in hydrogels.
Assessment of initial investment strategies for different farm-scale scenarios with economic cost analyses in offshore salmon farming
(Walter De Gruyter Gmbh, 2024) Yiğit, Ümüt
The simulation of investment strategies with different farm-scale scenarios has been evaluated for best management plan in cage farming business for the establishment of a salmon production with either full capacity - or progressive investment. Economical revenues were analyzed with business risk assessment based on operating-and fixed costs for each of the four scenarios. In the theoretical model projected for the stimulation of best management plans, structural elements for the construction of an offshore Turkish salmon farm in the Black Sea were designed and investment costs for an annual production capacity of 4,000 tons were re-scaled by 25, 50 and 75% reduction, corresponding to 3,000, 2,000 and 1,000 tons per year, respectively. Economic variables of operational costs were comparatively evaluated with the revenues and annual profit conditions by sales of harvested fish. The break-even points for all investment strategies with different farm-scale scenarios were remarkably lower (on average 302,574.7 kg/year) than the harvest yields from the farms (on average 3,702,857.1 kg/year). Based on break-even points and margin of safety (MOS over 85%), all farms gained net profits with low risks in the first year, whether the farm received full investment, or initiated business with reduced investment expenditures for a gradual and progressive expansion plan. Findings of this study exhibit useful indications for farm management in understanding conditions of a step-wise establishment of business plans for salmon farming in offshore conditions.
Exploring ChatGPT's role in healthcare management: Opportunities, ethical considerations, and future directions
(Routledge Journals, Taylor & Francis Ltd, 2024) Atalan, Abdulkadir; Keskin, Abdulkadir; Özer, Süleyman
The ChatGPT initiative, an advanced AI application, has gained significant attention in diverse sectors, including business, technology, and research. Despite its novelty, it has been accepted across various domains, sparking discussions and shaping roadmaps. This article reviews different perspectives on ChatGPT, highlighting existing literature's prevailing lack of standardized evaluation methodologies. The study examines ChatGPT among natural language processing models, exploring its merits, drawbacks, limitations, and future expectations for its application in health quality and management. A meticulous analysis of 104 publications, covering titles, abstracts, and keywords, was independently conducted, addressing four main and seven sub-subjects. The review utilized PubMed, Scopus, Google Scholar, ScienceDirect, and preprint databases such as medRxiv, arXiv, and SSRN to select relevant articles. ChatGPT is expected to efficiently process and analyze extensive healthcare data, facilitating data-driven decision-making for healthcare organizations to enhance their services. However, it is crucial to acknowledge that ChatGPT models are incomplete substitutes for human healthcare professionals and have limitations in addressing complex medical issues. Consequently, this study underscores the imperative for full human supervision in medical services, emphasizing the essential role of humans in ensuring the quality and effective management of healthcare services.
Cheliped loss and abnormalities of the narrow-clawed crayfish, Pontastacus leptodactylus (Eschscholtz, 1823) (Crustacea: Decapoda: Astacidae)
(Soc Brasileira Carcinologia, 2024) Berber, Selçuk; Kale, Semih; Acarlı, Deniz
Heterochely is an important phenomenon in decapod crustaceans. Nevertheless, it was rarely examined in freshwater crayfish. Therefore, the aim of this study was to investigate cheliped loss and abnormalities of the narrow -clawed crayfish, Pontastacus leptodactylus. The crayfish samples were captured using 17 mm mesh -sized fyke-nets from Atikhisar Reservoir in canakkale, Turkey between July 2020 and June 2021. The cheliped loss was classified and compared between sexes and length groups. The cheliped surface was calculated for each specimen for both the right and left cheliped. Results of the study indicate that the percentages of the sampled individuals were 5.46% for the right cheliped missing group, 5.23% for the left cheliped missing group, 10.37% for both chelipeds missing group, and 78.94% for both chelipeds present group. There was a statistical difference between cheliped loss and size groups (p < 0.05). Although cheliped loss is almost non-existent in low -size groups (10.0-29.9 mm), it reaches high values in the 40.0-69.9 mm size groups. The most intense loss occurs in the 40.0-49.9 and 50.0-59.9 mm size groups. It was determined that 10.69% of the sampled individuals examined had a single cheliped (10.03% female, 11.14% male). A statistically significant difference was found between cheliped loss and sex (p < 0.05). The percentage of female and male individuals with no chelipeds is 9.83% for females and 10.73% for males, and with both chelipeds it is 80.14% for females and 78.14% for males. While the number of abnormalities observed in chelipeds was higher in males, abnormalities in both chelipeds were higher in females. Moreover, it was found that cheliped loss significantly differed according to the months of collection (p < 0.05). Cheliped losses increased in July, August, and September when feeding was comparatively intense. In conclusion, the fact that the individuals were obtained alive, was an indication that the abnormalities detected did not significantly affect their vital activities directly. However, morphological abnormalities in the appendages, especially in the chelipeds, may impair their functional use compared to a healthy cheliped. This abnormal condition is assumed to share the disadvantageous limitations experienced by the absence of a cheliped.
Length-Weight and Otolith Morphometry Relationships of Hoplostethus mediterraneus Cuvier, 1829 from the Saros Bay, Northern Aegean Sea
(Springer Int Publ Ag, 2025) İşmen, Ali; Yığın, Cahide Ciğdem; Öz, Melike İdil; Arslan İhsanoğlu, Mukadder
The relationship between total length (TL) and total weight (TW) and the morphometric relationships of the otolith between total length and otolith length (OL), total length and otolith weight (OW) and otolith length and otolith weight of Hoplostethus mediterraneus were examined in Saros Bay, North Aegean Sea, T & uuml;rkiye. The samples were collected with commercial trawls in Saros Bay from September 2006 to September 2008. A total of 970 specimens were caught at depths of 100-500 m. The average value of fish length was 11.86 +/- 0.14 cm (4.0-22.1 cm), and weight 32.2 +/- 1.0 g (0.83-148.75 g). Otolith size was measured with a minimum of 4.31 mm and a maximum of 12.88 mm. The relationships between TL and TW, OW and OL, OL and TL, OW and TL and OW and OL were determined as TW = 0.010*TL3.10 (r2 = 0.99), OW = 0.0004*OL2.64 (r2 = 0.99), OL = 0.055*TL + 0.564 (r2 = 0.98), OW = 0.0002*TL2.38 (r2 = 0.98), and OW = 0.0004*OL2.64 (r2 = 0.99). The high correlation coefficients (r(2) values) demonstrate the reliability of the established equations, offering a robust framework for estimating the size and weight of this species based on otolith measurements. This study provides crucial insights into the growth patterns and morphometric relationships of Hoplostethus mediterraneus, which can be used to enhance fishery management and conservation efforts in Saros Bay.
Distribution of the critically endangered fan mussel Pinna nobilis population in the Canakkale Strait and Marmara Sea
(Ege Univ, Fac Fisheries, 2024) Acarlı, Sefa; Acarlı, Deniz; Kale, Semih
This study was conducted with the primary objective of determining the presence of both healthy and impacted Pinna nobilis populations along the European coasts of the Sea of Marmara, followed by the identification of P. nobilis abundance and survival rates in the region encompassing the Canakkale Strait and the southern coasts of the Sea of Marmara. Underwater surveys were randomly conducted at 19 distinct stations, including 8 stations along the European coasts of the Sea of Marmara, 7 stations along the southern coasts of the Sea of Marmara, and 6 stations within the Canakkale Strait. SCUBA diving equipment was utilized to record information on habitat structure, water temperature, depth, and visibility at each station. The transect length during underwater surveys and the number of transects at each station were determined based on the condition of the seabed and the size of the area, respectively. Throughout the study period (September 2021 and October 2023), water temperature fluctuated between 17.5 degrees C and 26.6 degrees C. At the end of the study, a total of 395 individuals (147 live, 248 dead) were observed, with live individuals exhibiting total lengths ranging from 16.4 cm to 50.9 cm. This study represents the first investigation into the spatial distribution of P. nobilis along the European coast of the Marmara Sea. The study contributes significantly to enhancing our understanding of the ecology of P. nobilis populations in both the Sea of Marmara and the Canakkale Strait. Additionally, recommendations for the rehabilitation of impacted populations and the conservation of healthy populations have been provided for decision-makers and fisheries managers.
An extensive review of human health benefits from consuming farmed or wild fish with special reference to gilthead seabream (Sparus aurata)
(2024) Yiğit, Ümüt; Ergün, Sebahattin; Yiğit, Murat
In public, there is a significant concern regarding the safety and quality of farmed fish that poses problems for fish farmers in marketing. There is widespread recognition that farmed fish are less healthy than their wild equivalent, mostly attributed to unhealthy farm conditions or the ingredients used in artificial diets for aquaculture. However, the nutritional quality of farmed -or wild-caught fish may differ based on regional variation or a cultural environment's complex aspects. Whether farmed or wild fish provide better product quality is a long-standing matter for consumer preferences and marketing. Information was collected from a wide range of references through an extensive literature review, and detailed evaluations were made on the health levels of cultured fish and natural fish in human consumption. Therefore, the present study provides an extensive review to address the differences in the nutritional contribution of farmed and wild fish for human consumers. Addressing the questions arising from consumers’ concerns will undoubtedly support farmers in their challenging marketing efforts.
Monthly variation of fatty acids, lipid quality index and metal content of Pontastacus leptodactylus (Eschscholtz, 1823) in Atikhisar Dam Lake (Çanakkale, Türkiye)
(Springer, 2024) Berber, Selçuk; Acarlı, Sefa; Bayraklı, Barış; Kale, Semih; Kızılkaya, Bayram; Vural, Pervin; Acarlı, Deniz
This study aims to investigate the metal content, fatty acid composition, lipid quality, and potential health risks of Pontastacus leptodactylus crayfish inhabiting Atikhisar Dam Lake. The research covers a 12-month period and includes both male and female individuals. The study investigated the metal content of crayfish specimens. In female individuals, the metal concentrations were ranked as Fe > Zn > Al > Cu > Mn > Se > As > Hg > Cd > Pb, while in male individuals, the ranking was Fe > Al > Zn > Cu > Mn > Se > As > Hg > Pb > Cd. The results demonstrate that Atherogenicity Index (AI) values for both genders range between 0.21 and 0.31, and Thrombogenicity Index (TI) values fall within 0.14 and 0.20. This indicates that crayfish meat is composed of healthy and high-quality fatty acids. In male individuals, omega-3 values range from 25.28 ± 0.380% to 28.34 ± 0.430%, and in female individuals, they vary from 22.98 ± 0.195% to 28.73 ± 0.871%. These findings underscore the absence of significant health risks associated with mercury levels in crayfish meat. Monthly meal calculations reveal that consuming female crayfish at an average of 4.35 servings per month for adults and 2.24 servings per month for children presents no health hazards. Similarly, the consumption of crayfish meat at an average of 5.29 servings per month for adult males and 2.72 servings per month for male children is deemed safe for health. Based on these results, the lipid quality of both male and female individuals from this species is found to be beneficial, as confirmed by risk–benefit assessments.
Hydrochemical and Bacteriological Status of a High Altitude Karstic Cave Stream (Güvercinkaya Cave: Çanakkale, Turkey) with Aquatic Macroinvertebrates Findings
(Çanakkale Onsekiz Mart Üniversitesi, 2022) Odabaşı, Deniz Anıl; Odabaşı, Serpil; Deniz, Ozan; Çakır, Fikret; Elipek, Belgin; Arslan, Naime; Özbek, Onur; Özalp, H. Barış
Caves are laboratories for many disciplines that work in natural sciences including mineralogy, biology, hydrogeology, and archaeology. In this study, bi-monthly samplings were carried out from three smapling locations within and around the Güvercinkaya Cave, a high-altitude cave located in nortwestern Turkey, to evaluate the hydrochemical and microbiological properties and the aquatic macroinvertebrates of the cave stream. Some parameters of the water including pH, electrical conductivity, temperature, oxidation-reduction potential, dissolved oxygen were measured in-situ, while elemental (70 in total) and ionic composition of water were analyzed in the laboratory. Microbiological analyses of the cave stream were examined through analyses of total bacteria, total coliforms, fecal coliforms, fecal Streptococcus, and Escherichia coli. According to the Piper diagram of hydrochemical data, the cave stream had mainly Ca-Mg-HCO3 character, on the other hand, the Schoeller diagram indicated a common water source in Güvercinkaya cave due to the similar components of the main ionic components of the water. As a result of microbiological analysis, fecal contamination was determined, indicating an active wildlife in the cave. Additionally, several aquatic macroinvertebrates taxa, Rhynchelmis limosella, Dugesia sp., Gammarus uludagi which have non-troglobiont character were found in the cave stream. Rhynchelmis limosella detected in this study is the first record for the Turkish fauna.
BEM modelling of a hydrodynamic lifting surface working in ground proximity
(Elsevier Ltd, 2024) Coşgun, Taner; Özdemir, Yavuz Hakan
Present paper aims to assess the performance and limits of boundary element method for the reliable simulation of ground effect phenomena on hydrodynamic lifting surfaces. Benefitting from the ground effect, especially in extreme ground proximity, suggests a promising concept for lifting bodies. On the other hand, the more pronounced the ground effect, the more complicated flow physics it exhibits, making the problem harder to handle numerically. In this study, a potential-based boundary element method (BEM) is applied to the flow past a 3D rectangular wing within a wide range of ground clearances corresponding to out of ground effect (OGE), in ground effect (GE) and extreme ground effect (EGE) conditions. Both positive and negative angles of attack are tested to examine the lift and downforce producing cases. The potential flow around the airfoil is computed using the mixed constant-strength source and constant-strength dipole based panel method. The results show that BEM successfully predicts the lift force variation for a wing working in ground proximity (GE). However, approaching the bounds of extreme ground effect is seen to introduce a progressive decrease of the fidelity of the method. A similar tendency is observed in the downforce generating conditions, which is also an important scenario for ground vehicle aerodynamics. BEM remarkably overestimates the magnitude of the downforce when the ground clearance reaches up to the EGE conditions, still, it produces quite satisfactory results for the rest of the tested configurations. The pressure distributions are also provided to examine the flow field in the aforementioned cases. Overall, the results lead us to conclude that BEM stands as a robust and reliable prediction tool for ground effect on 3D wings but the extreme ground effect condition represents the limit of its accuracy range.
Multiple exposure to thunderstorm-sound in Nile tilapia (Oreochromis niloticus): physiological response and stress recovery
(Sciendo, 2023) Kuşku, Halit; Yiğit, Murat; Yılmaz, Sevdan; Yiğit, Ümüt; Ergün, Sebahattin
The present study investigated the impacts of multiple thunderstorm-sound exposures on growth and respiratory parameters in Nile tilapia (Oreochromis niloticus) in order to evaluate the acoustic stress response. Thunderstorm-sound exposure for 3 hours triggered respiration speed with an alarm reflex and rapid elevation of opercula beat rate (OBR) and pectoral wing rate (PWR), which increased two-fold over the control with no sound treatment, and peaked (OBR, 71.33±5.86 beat/min; PWR, 75.00±3.61 beat/min) in 10 hours after initiation of sound. Thereafter, respiration rates declined over the following days and returned to near-initial levels (45.33±4.04 beat/min OBR and 43.00±1.00 beat/min PWR) by day 3, an indication that fish recovered from thunderstorm-sound stress after 3 days of exposure. However, the same reaction course was observed each time of multiple sound exposures, repeated 20 times in a row with 4-day intervals, underlining that fish could not attune to repeated thunderstorm sound. Reduced voluntary feed intake as a result of anxiety and appetite loss was recorded in fish exposed to multiple thunderstorm sound, resulting in 50% less growth compared to those without sound treatment by the end of the 80-day experimentation. Therefore, it is advisable to monitor fish behavior during the 3-day stress period after a thunderstorm event in order to prevent waste from excess feeding, that in turn may contribute environment-friendly aquaculture for the future and sustainability of the oceans.
Analysis of the economic performance of salmon farming in submerged and surface cages in the Black Sea
(Springer Science and Business Media Deutschland GmbH, 2023) Yiğit, Umut; Yiğit, Murat; Ergün, Sebahattin; Kuşku, Halit; Ek, Hüseyin; Maita, Masashi
The production period for salmon farming in the Black Sea comprises the winter period and is limited to seven months, due to high water temperatures during the summer time. As an alternative strategy, temporary cage submersion during the summer season might be a solution for salmon grow-out throughout the year. Therefore, this study was conducted for comparative evaluation of economic performance of submerged and surface cages, by analyzing structural costs and returns for Turkish salmon farming in the Black Sea. As a result of the temporary cage submersion strategy, economic profits increased by nearly 70%, granting higher values of financial indicators with increased net profit (685,652.5 $ year−1) and margin of safety (89.6%), compared to the traditional surface cage (397,058.5 $ year−1 net profit and 88.4% margin of safety). The “What-if” analysis showed that profits from both cage systems were sensitive to variations in sale price, and the simulation by 10% reduced export market value may decrease revenues, with less financial profit loss for the submerged cage over the surface once. Hence, temporary cage submersion seems to be an alternative farm management strategy with extended production cycle and higher profits for the sustainable development of Turkish salmon farming in the Black Sea.
Temporal and spatial effects of environmental variables on crustacean communities in Çardak Lagoon (Turkish Straits System) under the influence of domestic pollution
(Springer Science and Business Media Deutschland GmbH, 2023) Ateş, Abdullah Suat; Mülayim, Ayşegül; Bakır, Ahmet Kerem; Acar, Seçil; Büyükateş, Yeşim; Dağlı, Ertan; Doğan, Alper; Uzundumlu, Sinan; Kedioğlu, Çetin
This study presents the temporal and spatial effects of domestic pollution on crustacean assemblages in a protected area, Çardak Lagoon (Turkish Straits System). The samplings were performed from sandy and mud (silt + clay) bottoms between 1 and 1.8 m depths in October 2018, February, April, and June 2019. A total of 6920 specimens and 26 species (1 Isopoda, 1 Tanaidacea, 2 Mysidacea, 3 Cumacea, 5 Decapoda, 14 Amphipoda) belonging to crustaceans was found. Highest crustacea abundances were in autumn and winter. Considering the environmental variables, NO2 + NO3 (mg L− 1) and COD (mg L− 1) levels in the water had the highest correlations with abundance for the sampling periods. According to sampling points, the highest correlation value was found between anionic detergent content in the water and the abundance. Crustacean community structure was modified by environmental variables of anthropogenic origin at a higher level. Oxygen, oxygen reduction potential, NO2 + NO3, total nitrogen, chemical oxygen demand and anionic surfactant levels in water and sediment sand content % were major environmental variables affecting the crustacean abundance in the study area temporally.
Wave field generated by finite-span hydrofoils operating beneath a free surface
(Brodarski Institute, 2021) Özdemir, Yavuz Hakan; Coşgun, Taner; Barlas, Barış
The present paper focuses on the numerical investigation of the flow around the fully submerged 2D and 3D hydrofoils operating close to a free surface. Iterative boundary element method is implemented to predict the flow field. This study aims to investigate the aspect ratio effect on the free surface interactions and hydrodynamic performance of the hydrofoils under a free surface by using potential flow theory. Three different submergence depths and aspect ratios are studied in the wide range of Froude Numbers. In 3D cases, spanwise width of the numerical wave tank model is selected both equal and wider to the foil span, to observe the sidewall effects. Wave field seems to be two dimensional at low Froude numbers. On the other hand, signs of three dimensionalities are observed on the free surface structure for higher Fn, even the predicted wave elevations are very close to 2D calculations in the midsection. Increment in the Fn give a rise to the amplitude of the generated waves first, however a further increase in Fn has a lowering effect with the beginning of waves spill in the spanwise direction in the form of Kelvin waves. Free surface proximity and resultant wave field are also seeming to be linked with the lift force on the hydrofoil. As aspect ratio of the foil increase, 3D lift values are getting closer to those of 2D calculations. However, it is seen that, 3D BEM predictions of a hydrofoil under free surface effect cannot be considered twodimensional even the aspect ratio is equal to 8.
Levels of toxic metals in edible fish species of the Tigris River (Turkey); Threat to public health
(Elsevier B.V., 2021) Töre, Yalçın; Ustaoğlu, Fikret; Tepe, Yalçın; Kalıpcı, Erkan
Tigris River has international importance as it runs through the borders of three countries. The levels and probable public health risks of heavy metals (Mn, Cd, Fe, Cu, Ni, Zn, Co, Pb, Cr, As) in 72 muscle and gill samples out of six fish species in Tigris River, Turkey were determined then compared with results of prior studies. Furthermore, human health risk levels from fish consumption were assessed using multiple approaches. The mean maximum heavy metal levels in the muscles were as follow; 175.88 > 22.34 > 10.29 > 2.81 > 2.76 > 1.68 > 0.33 > 0.25 > 0.05 = 0.05 mg kg−1 for Fe > Zn > Mn > Cu > Ni > Cr > Pb > As > Cd = Co, respectively. The highest muscle tissue levels for 8 heavy metals out of 10 measured were found in C. macrostomus species. The mean max. levels of Cu and Pb, the remaining two heavy metals, were measured in muscle tissue of L. abu species. The mean maximum concentrations of heavy metals of Cr, Cu, and Zn in all fish samples were below the maximum permissible limits (MPLs). The carcinogenic risk (CR) values for Pb, Cr, Ni and As were calculated and evaluated respectively in all of the Tigris River's fish species. While CR values calculated for Pb in all species did not pose a risk, it was found above the threshold value of 10−4 for some fish species for Cr, Ni and As. Target hazard quotients (THQs) from metal intake by consuming fish species were below 1 for all heavy metals which indicated no hazard from consumption. In addition, since the hazard index (HI) is lower than “1″, it has been concluded that the consumption of fish species will not pose a potential health risk. Considering by CR values exclusively, the results disclosed that the intake of the analyzed fish species might cause a toxicological hazard and impend to community health.
Length-weight relationships for 57 fish species of Bakircay river estuary in Candarli bay
(Parlar Scientific Publications, 2021) Babauglu, Ali Ozcan; Bayhan, Bahar; Kara, Ali; Acarlı, Deniz
Known as the fourth longest river in the Aegean sea with its 129 km length, the Bakircay River flows into candarli Bay in the north of Aegean sea. This study was conducted to measure length weight relationships (LWRs) of fishes captured with different fishing gears in the estuary of Bakircay River. This is the first study on this subject. The fishes that caught by each gear and carried in boxes to the lab were measured for total length (TL) as cm and wet weighed (W) as g. The length-weight (LW) relationships were estimated by W=aL(b). The level of statistical significance for r(2) was determined with LogW=loga +blogn. LW relationships were calculated in 57 fish species of 27 families from Bakircay River Estuary in candarli Bay. 3487 fish samples were caught with beach seines, handlines, longlines, fyke nets, scoop nets, cast net and trammel net between November 2012 and December 2015. The number of the samples ranged from 9 individuals for Gusterosteus actileants to 133 ones for Solen spiera, r(2) values varied from 0.84 to 0.99. All regressions were highly significant (p<0.01). The value h of the LW regression changed between 2.371 in Engraulis efricrasicohrs and 3.490 in Syngnathus acus with a median of 3.134 where 25-75% of the values changed from 3.010 and 3,170. Species of Sparidae. Mugilidae and Gobiidae families were captured more than others, which can be accepted as a typical feature for Mediterranean estuarine areas.
Biodiversity of freshwater macroinvertebrates on Gokceada Island (North Aegean Sea, Turkey)
(University of Gdańsk, 2021) Odabaşı, Serpil
Island ecosystems have attracted the attention of scientists since the early days of science because of their formation and biodiversity. Despite their abundant freshwater resources, data on freshwater diversity of Gökçeada are incomplete, especially for macroinvertebrates. This study was conducted in a wide range of freshwater ecosystems on Gökçeada between May 2016 and September 2018. Sampling of macroinvertebrates was performed using a hand net from 34 pre-selected sampling sites on the island. A total of 78 aquatic macroinvertebrate taxa were found, 46 of which are new records for the island. The most common species during the study were Gammarus komareki and Bythinella gokceadaensis with a frequency of 25.93%, followed by Tubifex tubifex, Gammarus sp. and Caenis sp. with a frequency of 22.22%. Endemic and invasive species on the island were assessed according to their presence and frequency values. Based on the results of the current study and previous data, it can be concluded that Gökçeada is characterized by a remarkable species diversity compared to aquatic macroinvertebrates on other Aegean islands.

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