International Journal of Aquatic Biology
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Sublethal effects of malathion on behavior and hepatic gene expression of HSP70 and CYP1A in Persian Sturgeon (Acipenser persicus) fingerlings
Full text linkMalathion, an organophosphate pesticide widely used in agriculture, poses significant risks to aquatic ecosystems. This study investigated the sublethal effects of malathion on hepatic HSP70 and CYP1A gene expression in fingerling Persian sturgeon (Acipenser persicus). Fish were exposed to 0.05, 0.1, and 0.2 mg L?¹ malathion (corresponding to sublethal fractions of the LC??) for 7 days. Liver samples were collected at 1, 2, 4, and 7 days post-exposure, and gene expression was quantified using real-time polymerase chain reaction (PCR). Behavioral responses and mortality were recorded. No mortality occurred in any group; however, fish exposed to 0.2 mg L?¹ malathion exhibited reduced feeding, impaired swimming balance, and decreased activity, especially toward the end of exposure. HSP70 expression peaked on day 1 at the highest concentration (15.7-fold higher than the control) and then gradually declined. CYP1A expression showed a similar dose-dependent pattern, with the highest induction (19.29-fold) observed on day 4 in the 0.2 mg/L group. Heat map visualization confirmed temporal and dose-dependent expression dynamics. A significant positive correlation (r = 0.73, P<0.0001) between the expression levels of HSP70 and CYP1A suggested a coordinated stress response to malathion exposure. These results demonstrate malathion-induced modulation of oxidative stress and detoxification genes in Persian sturgeon, underscoring the utility of these molecular biomarkers for monitoring organophosphate pollution in aquatic species
Reproductive potential of male calanoid copepod Sinodiaptomus (Rhinediaptomus) indicus Kiefer: A potential live prey for fish larvae
No full textCopepods are a morphologically, physiologically, and ecologically highly diverse group with different reproductive characteristics and have evolved structural specialties of sperm form and spermatophore structure. These reproductive peculiarities are important for their implications in applied biology. Copepods are the preferred food for finfish and shellfish larvae due to their optimal size range and nutritive value. Although many copepod species are successfully mass-cultured, limited success is still reported in commercial-level production for use in aquaculture hatcheries. Unlike rotifers and Artemia, which reproduce by parthenogenesis and attain high-density production easily, copepods reproduce sexually, involving mate selection, a copulatory process, and leading to the transfer of spermatophores and fertilization of eggs. This necessitates an understanding of the reproductive biology of cultivable copepod species to establish effective culture protocols. The freshwater calanoid copepod Sinodiaptomus (Rhinediaptomus) indicus is a promising candidate for mass culture, and this article describes the reproductive biology of the male using histological and electron microscopic studies. The ultrastructure of the spermatozoon of this species is reported for the first time. Laboratory experiments showed long lifespan and high spermatophore production (34 in 25 days) in this animal, which is a key factor in deciding male-female ratio formulation in the inoculum for mass culture. It is suggested that the S. (R.) indicus could be an ideal species for mass culture and use as live feed in fish and prawn larval rearing
New data on the parasites and parasite communities of Rutilus rutilus (Linnaeus, 1758) from the Danube River, Bulgaria
No full textThe present study aims to provide new data on the parasites and the first data on the parasite communities of the roach Rutilus rutilus (Linnaeus, 1758) from the Bulgarian section of the Danube River. The fish were caught in 2019-2021 from three biotopes (Koshava, Kudelin, and Novo Selo). Fish samples were collected during spring, summer, and autumn. A total of 152 R. rutilus specimens were examined. Nine helminth species were isolated: three species of Trematoda, two Cestoda, two Acanthocephala, and two Nematoda. The component community and infracommunity of the roach from the Danube River, Kudelin biotope, were examined. Rutilus rutilus is a new host record for six helminth species in Bulgaria
Seasonal shifts in diet composition, stomach fullness, and trophic position of Synodontis serratus in Lake Nasser, Egypt
No full textAnalysis of Synodontis serratus' feeding habits is crucial to understanding its ecological role in Lake Nasser, Egypt. This study examined seasonal variation in stomach fullness in relation to diet composition and trophic level for S. serratus throughout the year, using 361 specimens collected from March 2023 to February 2024. The results from stomach content analysis indicated that S. serratus employed an omnivorous, opportunistic feeding strategy, characterized by significant consumption of benthic and pelagic organisms, including aquatic insects, diatoms, crustaceans, nematodes, mollusks, and protozoan zooplankton. There were also seasonal changes; the importance of zooplankton decreased during the summer, while both diet diversity and feeding activity diminished in winter. Stomach fullness reached its minimal levels during late winter and early spring before peaking after summer. The trophic level analysis showed that S. serratus mainly operates as a secondary consumer (mean trophic level 3.11), with peak values in March among smaller individuals. This is counterintuitive, given expectations regarding ontogenetic diet shifts and maturity, which would lead to increased resource-use efficiency due to body-size-scaled metabolic demand relative to food resource availability. These results underscore the adaptive dietary strategies exhibited by S. serratus and their prominent functional contribution to the food web, indicating that S. serratus is a key species for ecosystem resilience. This necessitates further exploration to guide fisheries management intervention strategies planned for Lake Nasser
Tissue-specific accumulation and species-level variability of microplastics in four freshwater fish from the Dez River, Iran
No full textMicroplastics (MPs) are emerging contaminants of global concern due to their persistence, bioaccumulation potential, and implications for both aquatic ecosystems and human health. This study explored MP contamination in four economically important freshwater fish species—Carasobarbus luteus, Arabibarbus grypus, Luciobarbus barbulus, and Oreochromis niloticus—collected from the Dez River in southwestern Iran. A total of 120 specimens (30 per species) were sampled near the Dez Dam using gill nets. Edible (muscle) and inedible (skin and gastrointestinal tract) tissues were analyzed separately for MP content following alkaline digestion with 10% KOH and vacuum filtration. Visual identification under a stereomicroscope was used to quantify and categorize MPs by color. Microplastics were detected in all species and tissue types, with significant interspecific variation. Carasobarbus luteus exhibited the lowest MP burden, significantly lower than O. niloticus and L. barbulus. No significant differences were found among tissue types, suggesting widespread tissue distribution. Color composition varied across species, with black MPs being the most abundant. Notably, green MPs were only observed in O. niloticus and L. barbulus. These findings highlight the impact of ecological traits, including feeding behavior and habitat use, on the risk of MP exposure. The detection of MPs in edible tissues highlights potential food safety concerns and underscores the need for routine monitoring of freshwater fish in affected river systems. This study reports the first evidence of MP contamination in fish from the Dez River and contributes to the growing body of data on freshwater plastic pollution in understudied regions
Impact of acute salinity exposure on physiological indices and survival of Caspian roach (Rutilus caspicus)
No full textIncreased salinity, a major stressor in aquatic environments, can significantly affect the health and survival of fish. The Caspian roach (Rutilus caspicus) is an economically and ecologically valuable species of the Caspian Sea; the decline in its stocks in recent years has heightened the need to study its adaptation to adverse environmental conditions. This research was conducted to investigate the effect of different salinities on hematological, biochemical, and histological indices in Caspian roach. In this study, 480 fish with an average weight of 15±2 grams were maintained under laboratory conditions at salinities of 0 (Control), 6, 12, and 15 ppt. Blood and tissue samples were collected at 36, 72, and 108 hours after placement in the specified salinity concentrations. Hematological and biochemical indices, as well as the pathology of liver, gill, and kidney tissues, were investigated. The results showed that as salinity increased, the numbers of red blood cells (RBCs), hemoglobin, and hematocrit increased. In addition, glucose and the enzymes ALT, AST, and ALP increased significantly (P<0.05). The activity of Na+-K+-ATPase in the gills initially increased and then decreased at high salinities, indicating the fish's attempt to maintain osmotic regulation. Histological studies showed that increasing salinity induced necrosis, hyperplasia, and severe damage in the gill, liver, and kidney tissues. In total, this research showed that high salinity negatively affects the health and osmotic regulation of Caspian Roach and increases mortality in this species
Allometry and sexual dimorphism of the mangrove climbing crab Metopograpsus latifrons from Magnesia Mangrove Forest, Virac, Catanduanes Island, Philippines
Full text linkMorphological adaptations associated with life history may be explained by studies on allometry and sexual dimorphism in animals. However, little is known about these concepts among the climbing crab species. Here, we investigated the allometric growth (relative growth) and sexual dimorphism of the mangrove climbing crab Metopograpsus latifrons from Magnesia Mangrove Forest, Catanduanes Island, Philippines in 2023 (April, September, and December) and 2024 (October). The results suggest that M. latifrons is positively allometric (both males and females) in the cheliped characters and abdomen. This reflects strategies in intrasexual resource competition (food and spatial resources) and abdominal adaptations related to reproductive systems, respectively. No sexual dimorphism is detected in the body size, indicating that the arboreal strategies of the species may not favor larger individuals. Sexual dimorphism, however, is present in the cheliped, which may be an advantage among males (confrontation, grasping, or courtship display) driven by sexual selection in its mangrove-related lifestyle
Structural surface properties of perspective marine antifouling coating based on bimetallic nanoparticles in organic matrix
Full text linkThe paper presents the results of a study on the potential protective anti-fouling coating obtained through the uniform distribution of bimetallic oxide nanoparticles containing copper and iron atoms within an organic matrix. The organic matrix was formed by mixing a suspension of the nanoparticles in xylene with a styrene-acrylic resin. Data on the dynamic light scattering of the initial xylene suspensions and similar suspensions stabilized by centrifugation are provided. The suspension produced an anti-fouling coating, which was investigated using atomic force microscopy and scanning electron microscopy methods. It is demonstrated that as the mass fraction of particles in the matrix increases, noticeable agglomeration occurs. Additionally, exceeding a mass concentration of 20% leads to their uneven distribution within the organic matrix. The results of testing CuO-FeCuO nanoparticles-based antifouling coating in seawater regarding its biocidal effect on heterotrophic bacteria are presented. It is shown that the coating reduces the microfouling effect by 85% compared to an unprotected similar sample
Bioactive properties of cuttlefish, Sepia pharaonis, ink extracted with different solvents
No full textCuttlefish ink, a multifunctional marine byproduct, has attracted increasing interest due to its bioactive properties and potential applications in the food, pharmaceutical, and other industries. This study investigated the antimicrobial activity, physicochemical characteristics, and biochemical composition of Sepia pharaonis ink extracted using various solvents. The well diffusion method revealed that isopropanol-extracted (IPA) ink exhibited the highest antibacterial activity (27±0.41?mm), while distilled water showed the lowest activity. Biochemical groups in ink and ink extract were identified by FTIR spectroscopy. The ink powder showed strong absorbance peaks followed by IPA, ethanol, and methanol, respectively. Different peaks of absorbance of ink powder and ink extracted with different solvents, indicating the presence of varying absorbance value peaks of phenolic, alcohol, and amine groups. Among the solvents, IPA exhibited absorbance peaks close to those of the ink powder. The FTIR transmittance was found to be significantly lower in the ink powder (76.2±0.04%) and in the ink extracted with IPA (83.81±0.03%). Proximate analysis indicated that ink powder contained higher levels of lipid (0.21%), ash (16.27±0.05%), and crude protein (45.99±0.72%) compared to ink extracts. The DPPH radical scavenging activity assay showed significantly higher activity in ink extracted with distilled water (66.21±0.12% at the concentrate test at 12.5 mg/mL) than with IPA (52.82±0.97% at the tested concentration of 1000 mg/mL). IPA demonstrated superior extraction efficiency, achieving an average yield of 101.31±0.51%. Regarding functional properties, the water absorption index (WAI) remained stable, while the water solubility index (WSI) increased significantly with longer mixing times, reaching a maximum value of 22.09±0.40 after 24 hours. These results demonstrate the potential of S. pharaonis ink, depending on the solvent type, to have a significant impact on the effectiveness and functionality of extraction. IPA serves as an effective solvent for ink extraction, exhibiting high absorption characteristics and a significantly larger antimicrobial zone, which indicates potent bioactivity. These findings suggest that IPA-extracted ink possesses promising potential as a natural antioxidant. Ink powder and ink extract have the potential to be implemented, and their commercial viability and safety can be evaluated in the future for biomedicine applications
Evaluation of organic pollution in Shatt al-Basrah Canal, Southern Iraq
No full textGiven the environmental importance of the Shatt al-Basra Canal, the current study aimed to examine organic pollution levels in the canal waters using the Organic Pollution Index (OPI) and the Nutritional Status Index (TSI) to identify the variables influencing organic pollution during the period from January 2023 to December 2023. Water samples were collected monthly from two stations. The measured environmental factors were water temperature 16-35?, salinity 47-20.2 ppt, DO 9-5 mg/L, BOD 0.65-0.10 mg/L, light transmittance 71-18 cm, nitrate 12.24-1.19 mg/, phosphate 0.63-0.13 mg/L, and ammonium 10.48-3.1 mg/L, and chlorophyll-a 61.18-10.4 mg/L. TSI values ??in the two study stations were 55.96-48.76, and the water quality assessment was within the well-nourished classification in all stations except for the second station, which was within the average nutrition classification. The results showed clear changes in OPI values ??(95.56-22.35). The water quality of the Shatt al-Basra Canal was classified as sixth (poor) at the first station (60.13), and decreased to fourth (weak) at the second station (41.10)