rss_2.0Sciendo RSS Feed for Oceanological and Hydrobiological Studieshttps://sciendo.com/journal/OANDHShttps://www.sciendo.comhttps://sciendo-parsed.s3.eu-central-1.amazonaws.com/64726157215d2f6c89dc63ac/cover-image.jpghttps://sciendo.com/journal/OANDHS140216https://sciendo.com/article/10.26881/oahs-2023.2.02<abstract> <title style='display:none'>Abstract</title> <p>Manzala Lake, the largest in Egypt’s Nile Delta, has significant human activity. The Lake’s ecological condition has recently been impacted by a significant increase in agricultural, industrial, and urban wastewater discharge. A valuable tool for monitoring the water quality of Manzala Lake is the sensitivity of invertebrate species to various types of pollution, such as radioactive contamination. Activity concentrations of radionuclides Radium-226 (²²⁶Ra), Thorium-232 (²³²Th), Potassium-40 (⁴⁰K), and Caesium-137 (¹³⁷Cs) were measured in water, sediments and benthic invertebrate samples in 2020. The benthic community’s spatial distribution and the radionuclides’ bioaccumulation were evaluated to determine possible relationships. Thirty taxa of benthic invertebrates were recognised. The data illustrated that the mean activity concentration of radionuclides in water was in the order of ⁴⁰K &gt; ²³²Th &gt; ²²⁶Ra &gt; ¹³⁷Cs, which changed into ⁴⁰K &gt; ²²⁶Ra &gt; ²³²Th &gt; ¹³⁷Cs in the sediment and benthic invertebrates. Gastropoda and Ostracoda are the dominating groups of benthos in the lake and are related to the highest concentrations of radionuclides. The benthos species with shells dominated at the sites with the highest activity concentration of ²²⁶Ra, while soft-bodied organisms dominated in sites with the highest average ¹³⁷Cs activity in these samples.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.2.022023-06-28T00:00:00.000+00:00https://sciendo.com/article/10.26881/oahs-2023.2.07<abstract> <title style='display:none'>Abstract</title> <p>Morphological asymmetry was analysed in two marine fish species <italic>Acanthopagrus arabicus</italic> and <italic>Planiliza klunzingeri</italic>, in brackish and freshwater habitats in southern Iraq. For both species, specimens from the Shatt al-Arab River and Shatt al-Basrah Canal exhibited greater asymmetry values for snout length. In both locations examined, the levels of asymmetry of the physical traits increased as the fish grew. The high levels of asymmetry in the two fish species may be linked to heavy metal pollutants in the two aquatic environments studied.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.2.072023-06-28T00:00:00.000+00:00https://sciendo.com/article/10.26881/oahs-2023.2.10<abstract> <title style='display:none'>Abstract</title> <p>Biodiversity in the Mediterranean Sea has not yet been fully explored. There has been very little research on molluscs along the Libyan coast. An individual of the chromodoridid nudibranch <italic>Felimare picta</italic> (<xref ref-type="bibr" rid="j_oahs-2023.2.10_ref_035">Philippi, 1836</xref>) was encountered during scuba diving at the Lido resort near the Tobruk bay basin. The sample was carefully transported to the lab in seawater, photographed, and identified. The current study revealed that <italic>Felimare picta</italic> was recorded for the first time on the Libyan coast. Despite <italic>Felimare picta</italic> being rather common in many Mediterranean regions, records of it on the southern Mediterranean coasts are extremely rare or absent. It may be concluded that this study represents not only the southernmost record of <italic>Felimare picta</italic> in the Mediterranean but also the first record of the species in Libya.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.2.102023-06-28T00:00:00.000+00:00https://sciendo.com/article/10.26881/oahs-2023.2.04<abstract> <title style='display:none'>Abstract</title> <p>The present study is a preliminary taxonomic survey of diatom assemblages from one of the highest mountain ranges in the Western Himalayas – Ladakh. 37 samples were collected from 19 different sampling sites at altitudes ranging from 3100–4552 amsl. The diatom communities were representative of habitats such as lakes, streams, and hot springs from high altitudes. The dominant diatoms are studied using light microscopy and identified using valve morphometrics. The study enlists a total of 74 taxa belonging to 40 genera along with photomicrographic plates. Commonly-found species of high-altitude hot springs habitats were <italic>Gogorevia exilis</italic> and <italic>Denticula thermaloides</italic>. <italic>Reimeria sinuata, Fragilaria vaucheriae, Gomphonella</italic> cf. <italic>olivacea, Encyonema ventricosum, Lindavia biswashanti, Diatoma moniliformis</italic>, and <italic>Denticula valida</italic> were commonly occurring species in stream, river and lake habitats. Further analysis and putative novel species from this high-altitude environment will be described in future publications.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.2.042023-06-28T00:00:00.000+00:00https://sciendo.com/article/10.26881/oahs-2023.2.09<abstract> <title style='display:none'>Abstract</title> <p>International food and raw material security issues has gained much more importance than ever. This study examines that the following questions ‘Who depends on whom?’ and ‘What is the level of dependency?’ considering relationships between “fisheries context” (catch and aquaculture production, total fisheries export and import, fisheries export and import value, fish consumption per capita, and processed fisheries product) and human development of countries (as Human Development Index-HDI). The overall result of the study pointed that the countries located in the highest categories in terms of HDI were both export and import-dependent. The most importance levels of dependency for the Low Developed Countries (HDI &lt; 0.550) were fish consumption, and total imports; for Medium Developed Countries (0.550 ≤ HDI &lt; 0.699) were export value, exports, and catch production; for High Developed Countries (0.699 ≤ HDI &lt;0.80) was total exports; for Very High Developed Countries-I (0.80 ≤ HDI &lt; 0.900) was exports; and for Very High Developed Countries-II (HDI ≥ 0.90) was import value. To improve the human development of the countries and maintain the food security around the world, the following points could be suggested: i) to increase the aquaculture production both in inland and marine environments where possible, ii) for low and medium developed countries, instead of raw material exporting, to support increasing the production capacity of processed fisheries products that have higher global market prices.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.2.092023-06-28T00:00:00.000+00:00https://sciendo.com/article/10.26881/oahs-2023.2.01<abstract> <title style='display:none'>Abstract</title> <p>Skates and rays, which are widely encountered in the by-catch of fisheries activities from the Sea of Marmara and banned for sale by regulation, are species that are discarded if caught. For this reason, in our study, we aimed to determine the bioactive potentials of these species, considered fishing waste, by investigating the skin secretions and microbial flora. In our study, both the skin flora and mucus contents of the discarded species <italic>Dasyatis pastinaca</italic> (Linnaeus, 1758), <italic>Myliobatis aquila</italic> (Linnaeus, 1758), and <italic>Raja clavata</italic> (Linnaeus, 1758) caught in the Sea of Marmara were investigated to determine their potential antimicrobial activities. A total of 164 bacteria were isolated from the epidermal mucus of the three batoid species. Antibacterial activity was observed from three isolated bacteria against <italic>Escherichia coli</italic>, Vancomycin-resistant <italic>Enterococcus faecium, E. faecalis</italic>, and <italic>Bacillus subtilis</italic>. Additionally, the highest antibacterial activity was observed for skin mucus of <italic>R. clavata</italic>. Mouse fibroblast cell viability was challenged with mucus secretions. <italic>M. aquila</italic> and <italic>R. clavata</italic> mucus secretions exhibited no observable change after 24 and 48 hours. The assays indicated that both the isolates and the skin mucus have potential antimicrobial activity against opportunistic pathogens.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.2.012023-06-28T00:00:00.000+00:00https://sciendo.com/article/10.26881/oahs-2023.2.03<abstract> <title style='display:none'>Abstract</title> <p>A new record of Siganus sutor from inland artificial marine extension Shatt al-Basrah canal, south of Iraq, is reported. Two specimens were collected during an ichthyologic survey on 2 November 2021. The specimens are 127 and 129 mm in total length. This record from Iraqi waters represents the species’ second and northernmost appearance in the northern Indian Ocean.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.2.032023-06-28T00:00:00.000+00:00https://sciendo.com/article/10.26881/oahs-2023.2.06<abstract> <title style='display:none'>Abstract</title> <p>One hundred and twenty asterisci were obtained from 30 specimens each of <italic>Cyprinion kais</italic> and <italic>Cyprinion macrostomum</italic>. Significant relationships between otolith mass and the three fish lengths (TL, SL, and FL) were attained for <italic>C. kais</italic>. Similar associations were obtained for OL and the three fish lengths of <italic>C. macrostomum</italic>. For <italic>C</italic>. <italic>kais</italic>, the highest in the relation between otolith mass, hereafter referred to as OM, and fish fork length, henceforth known as FL (0.5894). The lowest coefficient of determination was observed between otolith width, hereafter called OW, and standard fish length, hereafter referred to as SL (0.2861). For <italic>C</italic>. <italic>macrostomum</italic>, the highest coefficient of determination was attained for the relation between OL and FL (0.7280) and the lowest for the relationship between OM and TL (0.1717). The analysis shows that evaluations of the body size of the two fish species investigated through biometric studies of otoliths are trustworthy.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.2.062023-06-28T00:00:00.000+00:00https://sciendo.com/article/10.26881/oahs-2023.2.05<abstract> <title style='display:none'>Abstract</title> <p>Although the number of studies documenting the presence of Microplastics (MP) in fish is increasing, research studies focused on its detoxification are very limited. In this study, rainbow trout (<italic>Oncorhyncus mykiss</italic>) were randomly divided into two groups after being fed with MPs (15% polypropylene [PP] +15% polyethylene [PE]) for 2 months. MP excretion without any application (PP+PE) in group I fish, and excretion of MPs with hydrogen-rich water (HRW) application (PP+PE+HRW) in group 2 were investigated under semi-static conditions for 21 days. This effect was also compared by using positive and negative control groups (Control [no treatment, free PP, PE or/and HRW] and only HRW group). In this direction, the following were determined: PP+PE chronic toxicity in aquatic organisms, the toxicity mechanism and the effect of HRW as a possible treatment method in blood tissue; with hematological indices ([RBC count [RBC], leukocyte count [WBC], hemoglobin value [Hb], hematocrit ratio [Hct], platelet count [PLT], hemoglobin count per erythrocyte [MCHC], mean hemoglobin amount per erythrocyte [MCH] and mean erythrocyte volume [MCV]) in other tissues (liver, gill and brain tissue) oxidative stress response (catalase [CAT]), glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD), glutathione (GSH), reactive oxygen products (ROS), malondialdehyde ([MDA] levels), DNA damage (8-OHdG: 8-Hydroxy-2-Deoxyguanosine), and the apoptosis (caspase 3) levels were investigated. In addition, acetylcholinesterase enzyme (AChE) activity, which is important in neurotoxicity pathways in the brain, was determined. The presence of plastics (PP/PE) in target tissues (muscle, liver, gill and gastrointestinal tract) was also obtained.</p> <p>The results showed that PP+PE caused toxicity in all three tissues. MPs showed an inhibiting effect on antioxidant enzyme activities and an inductive effect on MDA, ROS, 8-OHdG, and caspase 3 levels. HRW showed a mitigating effect on MP-mediated toxicity in <italic>O. mykiss</italic> brain, blood, gill, and liver by controlling the ROS/GSH/MDA pathway. HRW can be suggested as a costeffective and eco-friendly curative for the protection of fish from the oxidative damages produced by the ingestion of microplastics.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.2.052023-06-28T00:00:00.000+00:00https://sciendo.com/article/10.26881/oahs-2023.2.08<abstract> <title style='display:none'>Abstract</title> <p>In this study, dissolved nutrients concentrations were measured monthly at downstream points of the two regional rivers (the Berdan and Göksu rivers) flowing into the Cilician Basin of the North-eastern (NE) Mediterranean Sea. The dissolved nutrients data obtained between September 2021 and August 2022 were used to determine riverine nutrient fluxes. This study showed that spatial and temporal variations were recorded in nutrients concentrations of the two regional rivers with the maximum values consistently recorded in the Berdan River having lower volume fluxes. The annual nutrient inputs of the two regional rivers indicated that higher amounts of dissolved nutrients were carried by the Göksu River due to its higher volume flux rate. The calculated molar ratios from total nitrogen (TN) and phosphorus (TP) fluxes ranged from 13 in the Göksu River to 22 in the Berdan River. The higher TN/TP molar ratio compared to the classic Redfield Ratio of N/P in the Berdan River is very likely to modify nutrient dynamics leading to further eutrophication in the shelf waters of the NE Mediterranean Sea.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.2.082023-06-28T00:00:00.000+00:00https://sciendo.com/article/10.26881/oahs-2023.1.08<abstract> <title style='display:none'>Abstract</title> <p><italic>Ceratophyllum demersum</italic> is a submerged, rootless, free-floating macrophyte and natural aquatic phytoremediation. <italic>C. demersum</italic> has high efficiency in absorbing large amounts of nitrogen and phosphorus in the aquatic environment. In this study, the effects of a natural phytoremediation <italic>Ceratophyllum demersum</italic> meal, as a dietary supplement, on growth performance, feed utilization, and body composition of common carp (<italic>Cyprinus carpio</italic> L., 1758) were investigated. This was the first attempt to use coontail as a feed additive for common carp. Four isonitrogenous (38% crude protein), isolipidic (8% crude lipid), and isoenergetic (18 kJ g⁻¹) diets were formulated control group (0%), CM5 group (5%), CM10 group (10%) and CM15 group (15%) in feed. Each dietary treatment was administered to triplicate in groups of 15 fish (~19 g). Carp were hand-fed to apparent saturation three times a day (09.00; 12.00 and 17.00). There was no difference between the control diet and 5% CM in terms of growth (final weight, weight gain, specific growth rate) and feed utilization (feed conversion rate, feed intake, feed efficiency) (<italic>p</italic> &lt; 0.05). Increasing algae levels in diets improved protein levels in body compositions while decreasing lipid. There was no sign of appeared fish health indicators (disease or deformity) in all diet groups. This study results showed that instead of soybean meal, 5.75% and 6.07% as natural phytoremediation, <italic>C. demersum</italic> optimized the best growth and feed utilization performance in carp diets.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.1.082023-03-20T00:00:00.000+00:00https://sciendo.com/article/10.26881/oahs-2023.1.04<abstract> <title style='display:none'>Abstract</title> <p>Common dentex (<italic>Dentex dentex</italic>) is a commercial species of fish that is a highly valuable food source living naturally near Mediterranean and Atlantic Coasts. Therefore, monitoring and maintaining common dentex habitats are of high importance. A total of 53 specimens were collected from 6 natural habitats (from the Eastern Aegean and from the Antalya coast, which is the closest coast to the Western Mediterranean), and one aquaculture facility in the Eastern Aegean Sea. The mitochondrial Cytochrome Oxidase I (<italic>COI</italic>) gene was used to detect a total of 26 haplotypes. Along with the <italic>COI</italic> gene sequence, real-time PCR and high-resolution melting analyses were performed as rapid and inexpensive alternatives. Sequence analysis showed that the highest haplotype diversity was obtained from the aquaculture facility in Karaburun and Antalya Locations, Turkey. Analysis of Molecular Variance (AMOVA)based on the haplotype frequencies resulted in 92.54% genetic variation within localities and 7.46% genetic variation between/among localities. The mean fixation index (<italic>Fst</italic>) was calculated as 0.0746 (<italic>p</italic> &lt; 0.001). Genetic distances were primarily in collaboration with geographical distances and were efficiently confirmed by high resolution melting (HRM) analysis. The results will be valuable in monitoring and maintaining natural habitats as well as aquaculture facilities where common dentex are grown.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.1.042023-03-18T00:00:00.000+00:00https://sciendo.com/article/10.26881/oahs-2023.1.10<abstract> <title style='display:none'>Abstract</title> <p>The sedimentation and resuspension of various forms of nitrogen in wetlands determines the direction of the nitrogen dynamics. Mogan Lake, in the Gölbaşı Special Environmental Protection Area, is one of the most important Ramsar-nominated wetlands in Turkey. Lake management applications have been performed by the local managers since 2008, including sediment cleaning activities such as dredging. In this context, the aim was to quantitatively predict the nitrogen dynamics (ammonium and nitrate release/uptake in the positive and/or negative direction) at the sediment–water interface, which has not been addressed in the eutrophication and sediment-related studies conducted to date on the lake in question. Sediment ammonium and nitrate flux were estimated to be between −9.16 and 0.36 µg m⁻² d⁻¹ and between −67.2 and 35.16 µg m⁻² d⁻¹, respectively. The estimations for sediment nitrogen flux in Mogan Lake did not show a regular seasonal or spatial fluctuation. Our results demonstrate that low nitrogen release levels in Mogan Lake do not pose a threat to its nutrient level. In conclusion, both monitoring and reducing external loading is still the top priority for a long-term recovery of water quality in the process of freshwater ecosystems.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.1.102023-03-20T00:00:00.000+00:00https://sciendo.com/article/10.26881/oahs-2023.1.02<abstract> <title style='display:none'>Abstract</title> <p>The present work aimed to understand the physicochemical and phytoplanktonic structure of the Kienke estuary water in the urban area of Kribi town in relation to human activities and fluvial or oceanic influences. Field investigations and laboratory work were devoted to the sampling and measurement of some physicochemical and biological parameters, specific treatments and classical statistics (descriptive, multidimensional) of variables. Estuary water is characterised by an instability and spatio-temporal variations in its physicochemical parameters. The most sensitive parameters are as follows: a temperature ranging between 22.6°C and 31°C under the influence of atmospheric variations, electrical conductivity and salinity that are relatively high (0.22 &lt; C. E &lt; 49.70 mS cm⁻¹; avg =16.56 mS cm⁻¹; 0 &lt; Sal &lt; 29.32 PSU; avg = 11.51 PSU), and a pH that is overall acidic to basic (6 &lt; pH &lt; 8.86; avg = 7.75 ± 0.82). The nutrients variation (ammonium, nitrite, nitrate and orthophosphate) is very low in space and time, with a longitudinal distribution controlled by tidal flows, river flows and the biological pump. For the 64 samples collected, 167 phytoplankton taxa were identified. The most abundant (36.36%) were Chrysophyta Division, followed by Chlorophyta. Species richness is marked by brackish water taxa. According to this structure and the combination of both gradients, mineratilisation and organic matter enrichment is of a physicochemical typology, and the biotypology is hydrotypologically dependent.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.1.022023-03-18T00:00:00.000+00:00https://sciendo.com/article/10.26881/oahs-2023.1.01<abstract> <title style='display:none'>Abstract</title> <p>This study analysed the ecological deterioration and health risk in sediment samples taken from Dalyan and Poyraz Lagoons in the Karacabey floodplain of Turkey, which is under pressure from agriculture, industry and settlement activities. Multi-element analyses were performed with ICP-MS on the surface and core sediment samples from the lagoons. Total organic carbon, chlorophyll degradation products and carbonate analyses were performed to determine the transport and illuviation dynamics of the elements. While Pb and Zn showed moderate enrichment at some sampling points, no enrichment of the other elements was detected. According to ecological risk analysis data, Cd and Hg posed a moderate ecological risk at some sampling points. The modified hazard quotient data indicated very high contamination of Ni, a high level of As contamination and significant Cr contamination. A carcinogenic health risk was detected from Ni, Cr and As due to the lithological characteristics of the basin. It was concluded that the lithological characteristics, the agricultural and mining activities carried out in the Susurluk Basin – which is drained by Koca Stream – and domestic and industrial waste contributed to the higher element concentrations in the Karacabey floodplain.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.1.012023-03-18T00:00:00.000+00:00https://sciendo.com/article/10.26881/oahs-2023.1.07<abstract> <title style='display:none'>Abstract</title> <p>The aim of this study from 2020 was to identify the role of rivers, including those with low water flow and a constant inflow of bisphenol A (BPA), 4-tert-octylphenol (4-t-OP) and 4-nonylphenol (4-NP) to the marine environment. Water samples were collected from the small rivers flowing into the Gulf of Gdańsk and from the Vistula River. Final assays were performed using high-performance liquid chromatography with a fluorescence detector (HPLC-FL). The highest concentrations of phenol derivatives were found in summer, most likely due to higher consumption of products containing phenol derivatives. Another factor may be the type of development in the catchment area. The measurements did not exceed the PNEC, though this does not mean that the amounts of phenol derivatives introduced into the Gulf of Gdańsk by rivers can be ignored. Mean loads of xenobiotics introduced to the sea via rivers have been calculated as over 320 kg y⁻¹ of BPA and about 55 kg y⁻¹ of 4-t-OP and 4-NP each.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.1.072023-03-20T00:00:00.000+00:00https://sciendo.com/article/10.26881/oahs-2023.1.09<abstract> <title style='display:none'>Abstract</title> <p>Surface water samples from the area of Munzur Stream in Türkiye (a Ramsar site) were evaluated for their suitability for irrigation and drinking purposes using different water quality indices. The human health risks were assessed as well. The study was conducted over a period of 24 months from January 2019 to December 2021 by taking samples from nine stations every month in order to determine the water quality of Munzur Stream, located in Tunceli. According to the results, Munzur Stream is in good condition in terms of the quality of drinking water and irrigation water. The concentrations of heavy metals such as Cu, Ni, Fe and Hg were high, though the water quality parameter according to Türkiye Ministry of Forestry and Water Affairs Surface Water Quality Regulations (TSWQR) was significantly lower than the permitted limits. In Munzur Stream, the irrigation water for all stations was reported to be excellent, good and suitable in terms of SAR, Na% and MH, respectively. The principal component analysis data formed the four principal components, explaining 98.22% of the total variance. The sources of pollution in this area include the rock types of the basin, soil erosion, domestic waste water discharge and agricultural flow of inorganic fertilisers.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.1.092023-03-20T00:00:00.000+00:00https://sciendo.com/article/10.26881/oahs-2023.1.06<abstract> <title style='display:none'>Abstract</title> <p>Lakes İznik and Manyas located in Türkiye are important biodiversity resources in the Palearctic region. No studies to date have explored the ecological statuses of these lakes together with their water quality based on biotic indices utilizing benthic macroinvertebrates. In this study, some parameters listed in the SWQMR of Türkiye were measured to determine the ecological quality of the lakes. Biotic indices included in the WFD and bacteriological parameters in terms of human health were also evaluated for these lakes. Sampling was performed at 6 stations in 2018-2019. Results for the zoobenthic community structure indicate that Lake İznik has started to become organically polluted and Lake Manyas is more polluted. Also, the biological index results for Lake İznik also show that the lake water quality has started to decrease and that pollution conditions have occurred, pointing to class III water quality. It is clear that there is pollution pressure in Lake İznik. However, according to the results, the macrozoobenthic community structure, diversity, and water quality of Lake İznik seem to be better than those of Lake Manyas. According to the results of the water qualities in the lakes, precautions should be taken to eliminate the negative pressures seen in both lakes.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.1.062023-03-20T00:00:00.000+00:00https://sciendo.com/article/10.26881/oahs-2023.1.03<abstract> <title style='display:none'>Abstract</title> <p>In the present study, intraspecific morphometric distribution of <italic>Spicara flexuosum</italic> was investigated along the five locations on the Turkish coast based on eight morphological characters. A total of 116 samples were obtained along the Turkish coasts (Istanbul, Yalova [Armutlu], Izmir, Mersin and Antalya) by using trawlers and the handline fishing method within the period in 2014–2015. Principal component analysis and the dendrogram-based Euclidean distance method were used to evaluate different morphometric traits among five locations. The most important ratios of the morphometric loading characters were the head length to interorbital distance, head length to eye diameter, maximum body height two to head height, and head height to head length. The classification matrix based on the discriminant function analysis showed that 94.7% of original grouped were correctly classified. Principal component and cluster analysis showed the existence of two morphologically differentiated groups of <italic>S. flexuosum</italic>. First one composed of Istanbul and Yalova and the second one consisted of Izmir, Mersin and Antalya. This study is the first description of the intraspecific distribution of morphometric characters for <italic>S. flexuosum</italic> along the Turkish coast as well as the Mediterranean region for fisheries management purposes.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.1.032023-03-18T00:00:00.000+00:00https://sciendo.com/article/10.26881/oahs-2023.1.05<abstract> <title style='display:none'>Abstract</title> <p>The current study aims to calculate and assess the asymmetry of the two goatfish species, Yellowstripe goatfish <italic>Mulloidichthys</italic> <italic>flavolineatus</italic> (Lacepède 1801) and Red Sea goatfish, <italic>Parupeneus forsskali</italic> (Fourmanoir &amp; Guézé 1976) collected from Hurghada fishing harbour, Egypt. The asymmetry valuation for <italic>M</italic>. <italic>flavolineatus</italic> and <italic>P. forsskali</italic> is imperative to demonstrate the impact of asymmetry on the larvae settlement in this vital fishing ground. Asymmetry was calculated for the saccular otolith (Sagittae) biometry, namely length, width, and mass. The results showed that the otolith height had a lower asymmetry value than the otolith length for the two goatfish species inspected. No relationship between the asymmetry value of otolith length and width and total fish length was observed. Both goatfish species’ calculated otolith mass asymmetry was higher than that of many teleost fish species.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.1.052023-03-18T00:00:00.000+00:00en-us-1