rss_2.0Oceanological and Hydrobiological Studies FeedSciendo RSS Feed for Oceanological and Hydrobiological Studieshttps://sciendo.com/journal/OANDHShttps://www.sciendo.comOceanological and Hydrobiological Studies Feedhttps://sciendo-parsed.s3.eu-central-1.amazonaws.com/64726157215d2f6c89dc63ac/cover-image.jpghttps://sciendo.com/journal/OANDHS140216A biomonitoring study of : metal bioaccumulation and current status in Iskenderun Bay, eastern Mediterraneanhttps://sciendo.com/article/10.26881/oahs-2023.4.09<abstract> <title style='display:none'>Abstract</title> <p>Concentrations of aluminum, chromium, cobalt, nickel, cadmium, lead, manganese, iron and zinc were determined in sea urchin species, <italic>Diadema setosum</italic> from Iskenderun Bay in December 2022. The level of metals was determined by Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). Concentrations of the heavy metals in the examined sea urchins ranged as follows: Al 0.07-7.17 μg g<sup>-1</sup>; Cr 0.07–0.8 μg g<sup>-1</sup>; Co 0.01–0.2 μg g<sup>-1</sup>; Ni 0.2–2.9 μg g<sup>-1</sup>; Cd 0.0–0.02 μg g<sup>-1</sup>; Pb 0.4-3.5 μg g<sup>-1</sup>; Mn 0.03–0.4 μg g<sup>-1</sup>; Fe 1.2-57.2 μg g<sup>-1</sup>; Zn 0.28–2.7 μg g<sup>-1</sup>, respectively. The highest accumulation of Fe and Pb metals was determined in the tissues of the sea urchin. The present study suggests that D<italic>. setosum</italic> could be a potential biological indicator of metal pollution in the Iskenderun Bay. Furthermore, soft tissues generally had lower levels overall. For this reason, the data show that <italic>D. setosum</italic> is a very good heavy metal collector and therefore may be used successfully to monitor heavy metal levels in Iskenderun Bay.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.4.092023-12-31T00:00:00.000+00:00Morphological comparison for the dorsal fin of , and (Teleosti: Siluriformes) collected from the Lake Nasser and the River Nile, Egypthttps://sciendo.com/article/10.26881/oahs-2023.4.03<abstract> <title style='display:none'>Abstract</title> <p>The anatomy, growth, and differentiation of the dorsal fin spines of three catfish species collected from the Nile River and Lake Nasser. Egyptian waters are described, and terminology is suggested for their parts. Features of the dorsal fin spine that change with growth are also described. The results showed that in all species studied, the dorsal spine is an elongate, compressed, tapered, slightly arched, osseous structure, bearing a series of retrorse dentations along the anterior and posterior surfaces and has a sharp sagittate tip. The retrorse, anterior dentations are most pronounced in the upper third of the spine and gradually alter in form until they appear as a series of distinct notches on the basal third of the spine. The anterolateral surfaces of the dorsal spine are marked by numerous short, irregular, shallow, anastomosing, longitudinal furrows. In three species (<italic>C. auratus, S. schall, S. serratus</italic>), the posterior process is poorly developed and directed laterally in young individuals and well produced and directed posteriorly in older specimens. In <italic>S. schall</italic> and <italic>S. serratus</italic>, the posterior blocking process of the large specimens has a wavy edge, while in <italic>S. serratus</italic>, it is curved in young individuals and straight in larger specimens.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.4.032023-12-31T00:00:00.000+00:00Defense responses of the green microalgae to the vanadium pentoxide nanoparticleshttps://sciendo.com/article/10.26881/oahs-2023.4.06<abstract> <title style='display:none'>Abstract</title> <p>Although vanadium-based nanomaterials have found extensive use in industry, their influence on ecosystems and living organisms is not yet well investigated. In this study, hydrothermal methods were utilized for the synthesis of vanadium pentoxide nanoparticles (V<sub>2</sub>O<sub>5</sub> NPs). The gained NPs were characterized using XRD, FT-IR, EDS, DLS, SEM and TEM techniques. Subsequently, the toxic effects of V<sub>2</sub>O<sub>5</sub> NPs on the model green microalgae <italic>Chlorella vulgaris</italic> were evaluated. According to the obtained results, V<sub>2</sub>O<sub>5</sub> NPs caused a significant reduction in cell number and biomass production of algae in a dose and time dependent manner. Moreover, flow cytometric analysis confirmed a reduction in the quantity of living cells. Scanning electron microscopy showed plasmolysis and deformation of the cells after exposure to nanoparticles. The photosynthetic pigments and phenolics content exhibited a decrease in comparison with the control sample. Although, non-enzymatic antioxidant system in <italic>C. vulgaris</italic> displayed an average action, antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) showed a dose dependent increasing trend. These intercellular reactions designated the activation of the antioxidant defense system in response to the induced oxidative stress by V<sub>2</sub>O<sub>5</sub> NPs.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.4.062023-12-31T00:00:00.000+00:00Species diversity, abundance, and distribution of freshwater prawns along a selected perennial stream in Ngangla Gewog, Zhemgang, Southern Bhutanhttps://sciendo.com/article/10.26881/oahs-2023.4.10<abstract> <title style='display:none'>Abstract</title> <p>The study and diversity of freshwater prawns are of great importance due to growing interest in biodiversity and its relative abundance. The present study was carried out for a selected stream divided into three different habitat types: namely, pond, run, and riffle. The study was focused on the diversity and abundance of prawns. To make it more systematic, a transect was laid upon the stream and it was divided into 30 plots with 100 m intervals. <italic>Metapenaeus rosenbergii</italic>, <italic>Penaeus japonicas</italic>, and <italic>Metapenaeus insolitus</italic> were species recorded in the pond habitat type only. The <italic>Penaeus</italic> genus was the most prominent in the study area while the genus <italic>Metapenaues</italic> was the least abundant. The diversity of freshwater prawns was found to be highest in the pond rather than the run and riffle. Documented information for prawn populations in Bhutan is sparse. Therefore, there is a wide research gap regarding prawn diversity in Bhutan. This study will help to establish a baseline data for the prawn distribution in the proposed study area. The present study will serve as a reference guide for future researchers.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.4.102023-12-31T00:00:00.000+00:00Antioxidant radical scavenging capacity and total carotenoid content of narrow-clawed crayfish (, Eschscholtz, 1823) in Atikhisar Reservoir (Çanakkale, Türkiye)https://sciendo.com/article/10.26881/oahs-2023.4.08<abstract> <title style='display:none'>Abstract</title> <p>In this study, antioxidant radical scavenging capacity and total carotenoid content in the meat and shells of <italic>Pontastacus leptodactylus</italic> were investigated. Concerning the antioxidant scavenging effect, the highest IC<sub>50</sub> values were found to be 388.77 mg g<sup>-1</sup> and 155.53 mg g<sup>-1</sup> for females and males in July and March, respectively. The mean IC<sub>50</sub> values of the meat were calculated as 239.83 mg g<sup>-1</sup> and 105.21 mg g<sup>-1</sup> for females and males, respectively. The mean total carotenoid content in the meat was found to be 14.35 and 12.78 μg g<sup>-1</sup> for females and males, respectively. The results indicated that crayfish meat had antioxidant radical scavenging capacity and was rich in carotenoid content.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.4.082023-12-31T00:00:00.000+00:00Metal pollution status and health risk assessment of beach sediments along the Mersin coast, Turkeyhttps://sciendo.com/article/10.26881/oahs-2023.4.07<abstract> <title style='display:none'>Abstract</title> <p>In the present study, the ecological risk assessment of metal contamination in beach sediments along the Mersin coast was determined using the metal contents of beach sediments in Mersin, Kızkalesi, Susanoğlu and Taşucu region obtained between 2006 and 2009. Furthermore, the potential health risk assessment for ingestion and dermal contact pathways of adults and children was determined. Ecological risk assessment of heavy metals showed that there is no pollution in the beach sediments for the metals Cu, Pb and Zn for the all studied coasts. However, the high ecological risk indices calculated in this study strongly suggested an apparent Cd, Cr and Ni pollution in the studied beach sediments due to natural and anthropogenic contamination. Study findings indicated the HI values were greater than 1 for the metal Cr. The TCR values were higher than 1.00E-04 for the metals Cr and Ni calculated for adults, and for the metal Cu, Cr and Ni calculated for children, respectively. All these findings showed that there is a high carcinogenic risk for adults and children resident in the Mersin province from carcinogenic Cr and Ni whilst the studied coasts have additional health risks to children from carcinogenic Cu.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.4.072023-12-31T00:00:00.000+00:00Utilizing fluctuation asymmetry to assess the effects of U-238 radioactivity on the marine ecosystem around the Madras nuclear power plant, Indiahttps://sciendo.com/article/10.26881/oahs-2023.4.05<abstract> <title style='display:none'>Abstract</title> <p>The monitoring of marine ecosystems is crucial due to the growing threat posed by nuclear power plants and other nuclear anthropogenic emissions. In our work, we used a straightforward and low-cost biomonitoring technique called fluctuation asymmetry (FA) to examine the variation between the left and right sides (developmental instability) of organisms’ traits that were influenced by genetic and environmental variables in the early stages of ontogenesis. The specimens of fish (<italic>Leiognathus</italic> sp.) and crabs (<italic>Portunus sanguinolentus</italic>) were collected seasonally and used as bioindicators to determine the effects of Uranium-238 (U-238) radioactivity around a nuclear power plant. The obtained results revealed that FA values were not considered typical values (FA = 0) in all seasons. Moreover, FA values of <italic>Leiognathus</italic> sp. exhibited insignificant fluctuation for a particular characteristic through the different seasons, while a significant fluctuation occurred amongst the characteristics themselves throughout the same season. Inversely, FA values of the four characteristics in <italic>Portunus sanguinolentus</italic> displayed seasonal variation amongst them all. Statistically, there was a strong positive correlation (<italic>r</italic> = 0.5, <italic>p</italic> &lt; 0.05) between U-238 radioactivity in the flesh of both organisms and the fluctuation asymmetry of different traits but it is not a sign that any radioactive pollution exists.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.4.052023-12-31T00:00:00.000+00:00Annual, seasonal and spatial differences in the growth rate of Baltic cod larvae and early juveniles in relation to zooplankton biomass fluctuations in 2006-2014https://sciendo.com/article/10.26881/oahs-2023.4.02<abstract> <title style='display:none'>Abstract</title> <p>It is an acknowledged theory that a faster growth rate, determined by various environmental drivers, may boost the survival of larval and juvenile fish. In this study we examined the differences in the growth rate of larval and juvenile cod (age 2 – 136 d; SL: 4.1 – 39.2 mm) between the years 2006 and 2014, sub-areas of the Baltic Sea (Bornholm Basin, BB; Słupsk Furrow, SF; Gdansk Basin, GB), and seasons (spring and summer). The average growth rate for all specimens was 0.25 mm/d, with significantly lower values between 2012 and 2014 than between 2006 and 2011. A reduction in zooplankton biomass, especially the large zooplankton fraction, was observed after the 2006–2008 period, which was related to the prevailing temperature conditions in the surface layers. The reduction in zooplankton biomass was accompanied by changes in the structure of zooplankton: less <italic>T. longicornis</italic>, <italic>C. hamatus</italic>, and <italic>Pseudocalanus</italic> spp., and more <italic>Acartia</italic> spp. The results suggest that the inter-annual differences observed in zooplankton biomass and structure are likely responsible for the observed reduction in the growth rate of cod larvae between 2012 and 2014 compared to the years between 2006 and 2011. The growth rate reduction could be one of the reasons for the decline in the recruitment of eastern Baltic cod between the years 2013 and 2015, after the high recruitment years of the period 2011-2012.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.4.022023-12-31T00:00:00.000+00:00Estimation of zooplankton density with artificial neural networks (a new statistical approach) method, Elazığ-Türkiyehttps://sciendo.com/article/10.26881/oahs-2023.4.11<abstract> <title style='display:none'>Abstract</title> <p>This study was carried out to predict the zooplankton density in the Cip reservoir (Elazığ) with an artificial neural network, using some water quality parameters. The plankton samples were collected monthly from Cip Reservoir in 2021- 2022, using a standard plankton net from three stations. Water temperature, dissolved oxygen, pH, electrical conductivity, secchi disk, alkalinity, total nitrogen and total phosphorus were measured. The actual values of zooplankton density and results obtained from the artificial neural networks were compared. Mean absolute percent error (MAPE) values were calculated with actual values and ANNs values. ANNs values were determined to be close to the real data. MAPE percentage value at the first station was determined as 1.143 for Rotifer, 0.118 for Cladocera, and 0.141 for Copepoda. The MAPE percentage value at the second station was determined as 0.941 for Rotifer, 0.377 for Cladocera, and 0.185 for Copepoda. The MAPE percentage value at the third station was determined as 0.342 for Rotifer, 0.557 for Cladocera, and 0.301 for Copepoda. In the present study, it has been seen that artificial neural networks with a learning feature are successful in predicting zooplankton densities in an aquatic environment. It can be concluded from the study that ANNs are a powerful tool for understanding their relationships with the environment</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.4.112023-12-31T00:00:00.000+00:00Differences of water chemistry, bird assemblages and nutrient loads introduced by waterbirds into morphologically similar waterbodieshttps://sciendo.com/article/10.26881/oahs-2023.4.04<abstract> <title style='display:none'>Abstract</title> <p>The number and structure of waterbirds is affected by the size of the waterbody, the presence of islands and macrophytes, but also by their trophy status. The aims of the study were to compare nutrients in water, numbers of waterbird assemblages, and the loading of nitrogen and phosphorus introduced by waterbirds in two similar waterbodies with different rates of water discharge. This study was conducted in two eutrophic shallow waterbodies, P1 and P2 in 2016 and 2017. The median concentrations of NO<sub>2</sub><sup>-</sup>, NO<sub>3</sub><sup>-</sup> and NH<sub>4</sub><sup>+</sup> were 4.0 times, 3.2 times, and 1.7 times greater in the P1 than in the P2 location, respectively. Similar proportions of organic matter in sediments were statistically greater in P1. The number of birds was also significantly greater in P1 than in P2. The waterbirds (<italic>Anas platyrhynchos, Aythya fuligula, Fulica atra, Phalacrocorax carbo</italic> and <italic>Chroicocephalus ridibundus</italic>) excreted 5.2 times more total phosphorous and 3.3 times more total nitrogen in P1 than in P2. Significant negative correlations were also found between the concentrations of NO<sub>3</sub><sup>-</sup> and the number of waterbirds in P1.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.4.042023-12-31T00:00:00.000+00:00An ichthyofaunal amendment with the length-weight relations and condition factors of some endemic and invasive freshwater fishes from Western Anatoliahttps://sciendo.com/article/10.26881/oahs-2023.4.01<abstract> <title style='display:none'>Abstract</title> <p>In the scope of this study, fish fauna of Küçük Menderes River and its tributaries, updated with the comparison of the recent ichthyofaunal studies, as well as the length-weight relations (LWR) and condition factors (CF) were estimated for 7 freshwater fish species belonging to six families from the river basin: endemic <italic>Oxynoemacheilus eliasi</italic>, <italic>Cobitis fahireae</italic>; invasive, <italic>Carassius gibelio</italic>, <italic>Atherina boyeri</italic>, transloce <italic>Perca fluviatilis</italic> and the native <italic>Squalius fellowesii</italic>, <italic>Cyprinus carpio</italic>. The fish samples were collected with various fishnets and DC electro-fishing devices from six stations in 2018 and 2019. The LWR of the fishes was studied based on 379 specimens. The estimated values of parameter b ranged from 2.884 (<italic>A. boyeri</italic>) to 3.176 (<italic>C. fahireae</italic>). The coefficient of determination (R2) was changed between 0.792 to 0.980 for all sampling localities. In the study, Fulton’s condition factor ranged between 0.391 (<italic>S. fellowesii</italic>) to 3.080 (<italic>S. fellowesii</italic>); the relative condition factor ranged between 0.346 (<italic>O. eliasi</italic>) to 2.746 (<italic>S. fellowesii</italic>), respectively. This research is anticipated to contribute valuable insights for the conservation of the species, while also furnishing essential data to inform future fisheries management studies in the region.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.4.012023-12-31T00:00:00.000+00:00Large branchiopods in extensive carp ponds – morphometric analysis of (Bosc, 1801) and (Waga, 1842)https://sciendo.com/article/10.26881/oahs-2023.3.10<abstract> <title style='display:none'>Abstract</title> <p>Large branchiopods is a group of poorly understood crustaceans which is highly threatened by the impact of human activities. Currently, their protection is difficult due to large deficiencies in documentation of their places of occurrence and not well researched ecology. After rediscovery of <italic>Streptocephalus torvicornis</italic> in Poland by Cukier in 2019, we conducted a survey to identify the species found at the Łąki Jaktorowskie Fisheries Research Station, Poland. This study consisted of observations and measurements of animals reared from cysts which had been obtained from soil samples taken at the nursery ponds in the study area. The following species were found: <italic>Limnadia lenticularis</italic>, <italic>Triops cancriformis</italic>, and <italic>S. torvicornis</italic>. We are presenting results of the morphometric measurements of <italic>T. cancriformis</italic> and the morphometric measurements of <italic>S. torvicornis</italic> from their only known population in Poland. Males were found in the <italic>T. cancriformis</italic> population, contrary to what has been documented previously. Large branchiopods have been repeatedly found in fishponds, and this work confirms the potentially high importance of ponds in the conservation of large branchiopods. With this study, we are drawing attention to the necessity of research about the distribution of large branchiopods in Poland.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.3.102023-10-09T00:00:00.000+00:00Seasonal changes in the reproductive cycle and condition index of the surf clam (Mollusca: Bivalvia) in the Gulf of Gabes, Tunisiahttps://sciendo.com/article/10.26881/oahs-2023.3.01<abstract> <title style='display:none'>Abstract</title> <p>The reproductive biology of <italic>Mactra stultorum</italic> from the Gulf of Gabes was investigated monthly during a one-year period (2017). This study is the first study examining its reproductive biology during one-year in the south of Tunisia. The overall samples presented a balanced sex ratio, with males dominating among smaller individuals (&lt; 22 mm) and females predominating in larger size classes (&gt; 34 mm). The obtained total sex ratio (F:M) was equal to 1.03:1. The size at first maturity (SL<sub>50%</sub>) was 20.43 and 22.10 mm for males and females, respectively. The seasonal variations assessed through macro- and microscopic characteristics in the gonads of both sexes indicated a clearly defined annual reproductive cycle with a principal spawning peak during summer and a resting period during December and January. The reproduction of <italic>M. stultorum</italic> was strongly influenced by fluctuations in the seawater temperature, as reflected through the temporal variation in the gonadal cycle, condition index (CI) and tissue weight rate (TiWR). If managed properly, <italic>M. stultorum</italic> is expected to meet the domestic market demand through artisanal fishery. The adoption and implementation of rules, such as limiting the size of clams, is required to protect this new exploitable fishery resource.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.3.012023-10-09T00:00:00.000+00:00Effect of touristic activities on seabirds’ habitat selection on sandy beacheshttps://sciendo.com/article/10.26881/oahs-2023.3.03<abstract> <title style='display:none'>Abstract</title> <p>Seabirds are biological models for habitat selection studies at different spatial scales. In general, seabirds select areas with a higher availability of prey, but human disturbances can modify their spatial and temporal foraging patterns in urban coastal ecosystems. Here we tested the hypothesis that human activities prevent seabirds foraging on beach sectors that are impacted by urbanization and recreational activities. Seabirds were counted while foraging at the interface between the surf zone and foreshore in three sectors with different levels of urbanization in southeastern Brazil. Physical variables, prey abundance, and human stressors, such as the number of people and dogs, were also measured. The brown booby <italic>Sula leucogaster</italic> foraged mainly in the least impacted sector, despite the lower abundance of prey and harsher physical conditions. The number of individuals of this species was negatively related to the number of people, indicating a human-induced avoidance behaviour. In turn, the kelp gull <italic>Larus dominicanus</italic>, a synatropic species, was more abundant in the high impact sector. Our results have implications for the management and conservation of sandy beaches, especially regarding the zoning and selection of priority areas for environmental protection and nature-based ecotourism activities.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.3.032023-10-09T00:00:00.000+00:00The effects of two different net modifications on reducing discards in the trammel net fishery for prawn in Mersin Bayhttps://sciendo.com/article/10.26881/oahs-2023.3.09<abstract> <title style='display:none'>Abstract</title> <p>The discarded species caught in prawn trammel nets damage the nets and cause a serious labor loss problem for fishers. In the present study, a 15 cm high greenhouse plastic film and a greenhouse shade cloth net were fitted between the lower parts of the nets and the lead collars to reduce discards in the trammel net fishery. The modified nets were tested in Mersin Bay with twenty-one fishing operations between September and December 2021. The results showed that, compared to commercial trammel nets, the nets equipped with greenhouse plastic film and greenhouse shade cloth did not significantly reduce the catch of the target species green tiger prawn (<italic>Penaeus semisulcatus</italic>). However, the total number of discards significantly decreased. The discard rates in the commercial net, greenhouse plastic film net, and greenhouse shade cloth net were 45%, 26%, and 22%, respectively. Furthermore, when the incomes from the nets’ hauls were calculated, the net equipped with greenhouse garden film and the net equipped with greenhouse shade cloth generated 24.77% and 14.41% more profit than the commercial net, respectively.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.3.092023-10-09T00:00:00.000+00:00An overview of the distribution and ecology of the alien cyanobacteria species , and in Europehttps://sciendo.com/article/10.26881/oahs-2023.3.06<abstract> <title style='display:none'>Abstract</title> <p>Cyanobacteria can form blooms and pose a threat to the functioning of freshwater ecosystems. Cyanobacterial invasions are expected to increase due to climate change. Alien species cause a decline in biodiversity by displacing native species, lead to extinctions, affect food webs, and produce cyanotoxins which potentially impact the environment and human health. Three species, <italic>Raphidiopsis raciborskii, Sphaerospermospis aphanizomenoides</italic> and <italic>Chrysosporum bergii</italic>, are considered non-native to European waters. Recently, they have expanded their native habitats and become established in temperate lakes. In this article, we provide a detailed overview of the countries where they are distributed and the occurrence of the blooms in Europe. We discuss the biotic and abiotic environmental factors that influence their establishment, as well as the characteristics of the species that make them so adaptable in non-native habitats. Understanding the interplay of these factors will allow us to better recognise patterns of invasiveness and predict their future threats to ecosystems.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.3.062023-10-09T00:00:00.000+00:00Complicated family relationships, or about taxonomic problems in the family Pyrenomonadaceae (Cryptophyceae)https://sciendo.com/article/10.26881/oahs-2023.3.04<abstract> <title style='display:none'>Abstract</title> <p>Cryptophytes, to which the Pyrenomonadaceae family belongs, are interesting organisms that occur almost all over the world and they are an important element of trophic chains in many ecosystems. The development of research methods and techniques, including electron microscopy and molecular studies, allowed for a better understanding of taxonomic relationships in this group of organisms. The Pyrenomonadaceae family currently includes three genera: <italic>Rhodomonas</italic>, <italic>Rhinomonas</italic>, and <italic>Storeatula</italic>, but their validity is being debated in the light of the latest data. The state of knowledge and the problems faced in the taxonomic revision of this family of cryptophytes are summarized in this article.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.3.042023-10-09T00:00:00.000+00:00Single and combined effects of dimethoate and malathion on oxidative stress biomarkers in the non-target freshwater mussel https://sciendo.com/article/10.26881/oahs-2023.3.07<abstract> <title style='display:none'>Abstract</title> <p>This study evaluates the single and combined effects of dimethoate (DI) and malathion (MA) on oxidative stress biomarkers in the freshwater mussel <italic>Dreissena polymorpha</italic>, estimating the potential harm of these pesticides on aquatic ecosystems. Superoxide dismutase (SOD) and catalase (CAT) activities, and glutathione (GSH) and lipid peroxidation (TBARS) levels were determined in <italic>D. polymorpha</italic> exposed to sublethal concentrations of DI, MA and a combination of the two during 24 and 96 h periods. The results showed that the GSH levels were decreased but the TBARS levels were increased in all the exposure groups after 24 and 96 h compared to the control. It was observed that SOD activity decreased but CAT activity increased in all the DI exposure groups after 24 h compared to the control. At the end of 96 hours, it was observed that CAT and SOD activities increased again in some exposure groups compared to the control. Exposure time also had an effect on biomarkers in different levels. According to the results, the cytotoxicity of DI and MA combination depended on their concentrations. DI or/ and MA, in sub-lethal concentrations, induced oxidative damages in <italic>D. polymorpha.</italic> Combined exposure of the pesticides can alter their toxicity and may be evidence of increased toxicity and oxidative stress.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.3.072023-10-09T00:00:00.000+00:00Distributions of (Macri, 1778) between the Kızılırmak and the Yeşilırmak coast of the Black Sea, Türkiyehttps://sciendo.com/article/10.26881/oahs-2023.3.02<abstract> <title style='display:none'>Abstract</title> <p>This study examined the seasonal distributions of the medusa <italic>Rhizostoma pulmo</italic> along the coasts of the southern Black Sea between Kızılırmak and Yeşilırmak between April 2008 and March 2010. Monthly abundance and biomass values were determined, as well as population parameters. The effect of temperature on medusa distribution was also investigated. Results showed that medusa abundance and biomass were highest in autumn, following a period of increased temperature. In contrast, medusa was not observed during the spring season. It was possible to observe the <italic>R. pulmo</italic> individuals for five months for the first term of investigation period (2008-2009), and seven months for the second term (2009-2010). The highest abundance value was found to be 10 n/m<sup>2</sup> (November 2008 and September 2009) and the highest biomass value was 12.587,5 g/100 m<sup>3</sup> (October 2009).</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.3.022023-10-09T00:00:00.000+00:00Plant balls from a Pomeranian lake, their invertebrate and microplastic componentshttps://sciendo.com/article/10.26881/oahs-2023.3.05<abstract> <title style='display:none'>Abstract</title> <p>Two balls with similar diameters (approximately 11–12cm) were found on the bottom of Lake Białe (Kashubian Lake District) at depths of 4m and 7m. The structures were made of tightly-packed plant remains represented mainly by decaying leaves of <italic>Larix</italic> sp. The balls were colonised by invertebrates (Tubificinae, Hirudinea, Isopoda, and insect larvae). They also contained pollutants, namely microplastics in blue, white, red, and black colours with a length from 500 to 1000 μm. Four other balls had been earlier reported by another diver in the same lake. According to a report of the local press, similar balls have also been found in Lake Bobęcińskie (Bytowskie Lake District). This article aims to record the first appearance of larch balls in this area.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.26881/oahs-2023.3.052023-10-09T00:00:00.000+00:00en-us-1