Iranian Journal of Fisheries Sciences
Volume:22 Issue: 6, Nov 2023

This histological study was conducted to discover the response of Litopenaeus vannamei to various levels of aflatoxigenic fungi (Aspergillus) toxicity. For this purpose, 400 specimens of live shrimp were gathered from a shrimp culture site in Iran. According to the results of the high-pressure liquid chromatography (HPLC) analysis, Aspergillus parasiticus had a higher production capability of total aflatoxin (TAF) (1073.804 ng g-1) compared to Aspergillus flavus (292.349 ng g-1). Two experiments with different toxicities of Aspergillus were assayed. In both experiments, the shrimps in 6 experimental groups were exposed to 0, 1, 5, 10, 15, and 20 ml of fungal spore suspension (FSS) in the feed (E1) and culture medium water (E2) in triplicate in each group for 4 weeks. The histopathology results of the gill tissue in the control group were normal. However, the inflammation, hemocytic infiltration, melanization, edema, and necrosis (as the main histopathological changes in the gill tissue) were observed after 28 days of the experiment when the toxicity of both experiments reached 18 µg kg-1 total aflatoxin and 1 ml FSS in E1 and E2, respectively. Furthermore, it was recognized that the histological alterations index (HAI) of gill was higher in E2 (0-130) than in E1 (0-74).

Zebrafish (Danio rerio) early-life stages of larvae were used to investigate behavioral, genetical and neurochemical changes promoted by the aquatic toxicity associated with the widely used medicines including naproxen (NPX) and titanium dioxide (TiO2), individually or in combination. Zebrafish as a biological model system genetically very similar to human. This study was carried out with a control (C) group and six treatments including TiO2 at 2 (2T) and 4 mg/L (T4), 50 µg/L (50N) and 100 µg/L (100N) of NPX, 2 mg/L TiO2+50 µg/L NPX (2T50N) and 4 mg/L TiO2 + and 100 µg/L NPX, (4T100N). Approximately 48 hours post-fertilization (hpf), the groups exposed to 4 mg/L TiO2 individually or in combination of 100 µg/L NPX induced large suites of symptoms in zebrafish (D. rerio) early-life stage, including hatching inhibition particularly in 50 and 100 µg/L exposed groups (10.0% and 10.3%, respectively), increased mortality specially in the group 4T100N (39.6%), high heart-beat, and few morphological abnormalities. At approximately 168 hpf, severing of the yolk sac and pericardium oedema, severe swim bladder inflation, short tail with axial malformation, and small eyes were other significant occurrences in D. rerio exposed particularly to 100 µg/L NPX, which can be collectively referred to as pigeon chest deformity. The results of mRNA expression of neurogenesis- and growth-associated genes of the targeted ones presented that gfap mitigated exception for 2T group compared to the control group. For mbp, fish of all groups showed downward gene expression, except for 100N group exhibited a normal expression compared to the control as well as the situation observed for AChE, although the fish showed relatively downward gene expression compared to the control group. The brain showed apoptosis as vacuoles in 4T and 50N groups. It is concluded that TiO2 had low acute toxicity to the embryos and larvae of D. rerio compared to NPX and could be used in different industries with low-risk rate, while it was used at low concentration (2 mg/L or less). although exposure to higher concentrations (4 mg/L or more) resulted in the increase of susceptibility risk of diseases.

The Persian Gulf waters, like other tropical regions, are rich in aquatic animal fauna and demersal trawling is one of the most common and practical methods to exploit aquatic resources. In the meantime, fishing vessels equipped with trawl nets can generate large amounts of bycatch and subsequent discards. This study aimed to identify fish species and estimate catch per unit area (CPUA) in the shrimp trawl bycatch off northwestern coasts of the Persian Gulf. The data were collected during trawl hauls for one year (September 2021– September 2022) between Delwar and Helle fishing grounds at three depth layers. The bycatch samples included 75 fish species with a total CPUA of 2392.4 kg/nm2. The largest amount of the discarded bycatch (77.8%) belongs to teleost and cartilaginous fishes, of which gilded goatfish and Japanese threadfin bream accounted for the first and second places with a total CPUA of 433.9 kg/nm2 and 202.8 kg/nm2, respectively. The abundance of the identified bycatch varied at different water layers, and the highest bycatch rate was obtained in the depth water (21-30 m; 44.1%) and the lowest value was recorded in the shallow water (up to 10 m; 21.7%). Fifteen fish species had percentage of occurrence (100%) at all studied depths. According to the distribution map provided by ArcGIS software, the density of discards was increased by moving toward the western part of the Persian Gulf. The assessment of the bycatch composition of traditional shrimp trawler fisheries is not only practical to take preventive actions regarding the marine ecosystem balance but also the results can be used as an ecological model to evaluate the risk of the trawlers in the study area.

Harmful algal blooms caused by dinoflagellates have significant adverse effects on environmental and public health. This study aimed to investigate the effect of water physicochemical parameters on the annual cycle of epiphytic dinoflagellates in the northern Chabahar Bay coastal waters of the Oman Sea (Iran). The macroalgal samples with associated epiphytes were collected seasonally from 6 coastal sites in spring, summer, atumn 2019 and winter 2020. The water physicochemical parameters were measured, and the data were analyzed using a one-way ANOVA and the principal component analysis (PCA). Twelve potentially toxic dinoflagellate species from five genera were identified during the four sampling seasons. Amphidinium carterae with an average of 11.22% and A. operculatum with an average of 10.77% of the total abundance of epiphytic dinoflagellates were the dominant species, and Gambierdiscus australes showed an average of 6.48%.Based on the PCA, the abundance of certain species was found to be influenced by different environmental factors. The PCA revealed that NO2, NO3 and SiO4 values had the greatest impact at sites with high abundances of A. operculatum, Prorocentrum concavum, P. emarginatum, P. rhathymum and G. balechii. Furthermore, PO4 concentration had the greatest impact at the sites with high abundances of A. carterae, P. lima, Ostreopsis lenticularis, O. heptagona, G. balechii, G. toxicus, G. australes and Coolia monotis. The results obtained highlighted a significant impact of dissolved oxygen, pH, salinity, temperature and nutrients on the epiphytic dinoflagellate species abundances in the study area.

Naproxen (NPX) is a nonsteroidal anti-inflammatory drug (NSAID) that has been identified in aquatic environments. It has led to growing concerns about endocrine disruption in aquatic organisms exposed to its drug residues. This study aimed to evaluate the disruptive effects of NPX and the improving effects of probiotic nutrition on thyroid, and zebrafish growth. The fish were fed for 60 days by basic diet (TN, Control) basic diet with probiotics (TP, TPN) (Lactobacillus reuteri, CFU/1.5×108) and simultaneously exposed to NPX (100 μg/L) (TN, TPN). During the experiment, Triiodothyronine (T3), Thyroxine (T4), Thyroid-stimulating hormone (TSH), Iodothyronine Deiodinase-1 (DIO1), and Iodothyronine Deiodinase-2 (DIO2), in addition to growth rate factors were evaluated with ELISA and Quantitative real-time PCR assay. The results showed probiotic feeding and NPX exposure did not affect T3 levels (p>0.05), but decreased T4 (p<0.05). TSH gene transcription expression increased as a result of probiotic feeding and NPX exposure (p<0.05) while DIO1 and DIO2 gene expression decreased (p<0.05). Weight gain and growth rate were also observed as a result of probiotic feeding, while exposure to NPX decreased growth rate (p<0.05). Generally, the results showed that NPX increased the risk of thyroid dysfunction and reduced growth rate in zebrafish, while probiotic feeding improved these factors. Therefore, the use of probiotic supplements in rearing centers is recommended due to the continuous increase in the consumption and distribution of drugs. Prolonged exposure to drug concentrations causes thyroid dysfunction and consequently reduced growth in fish, which will lead to significant economic losses.

Aquaculture plays a critic role in food security and supplying healthy foods. Replacing fishmeal and soybeans with new protein ingredients such as insect- and aquatic-based dietary compounds to reduce breeding costs is one of the priorities of the aquaculture industry. These new compounds are valuable sources of proteins, amino acids, fatty acids, vitamins, and minerals that can be used in aquatic nutrition. This article systematically reviews the effects of using these compounds on the quality and sensory properties of aquaculture products. The review of sources shows that the excessive application of these ingredients in the diet of farmed aquatic animals has a significant influence on their quality and sensory characteristics. Therefore, it is necessary to conduct a systematic review of published scientific sources in order to achieve reliable results. This study also highlights the importance of using quality and sensory analysis of aquacultured products when using new nutritional sources and provides practical information for aquaculture stakeholders, especially fish nutritionists.

This study was done to find the effect of different levels of curcumin on growth performance, immune response, and hematological markers in Siberian sturgeon, Acipenser baerii. For this purpose, a total number of 120 Siberian sturgeons with an average initial weight of 55.05±0.03 g (means±SD) were distributed into 12 tanks with 10 fish per tank (4 treatments with 3 replications) and fed four diets supplemented with 0 (base group, (C0), 0.5 (C0.5), 1 (C1), and 1.5 (C1.5) g kg-1 curcumin at 2.5% of body weight three times a day for 8 weeks. The highest final body weight (83.10 g), specific growth rate (3.12% day -1), and body weight increase (51.1%) were obtained in the fish fed with 1 g kg−1 curcumin (p<0.05). The highest number of red blood cells and white blood cells were measured in C1 treatment. The immune responses were significantly influenced by different curcumin levels in the diets (p<0.05). The alternative complement pathway, lysozyme, and respiratory burst activity were significantly increased, especially in the fish fed with 1 g kg-1 curcumin. In conclusion, the results indicated that 1 g kg-1 curcumin notably enhances growth and non-specific immune responses in Siberian sturgeon.

Population dynamics of skinnycheek lanternfish, Benthosema pterotum (Alcock, 1890), were studied in the Oman Sea from January to December 2019. A total of 2893 individuals were sampled from the commercial catch of bottom trawlers in the Oman Sea. The total length (TL) ranged from 21-60 mm and the average length was 39.4±4.64 mm. More than 84% of the samples were between 33-45 mm TL. The length-weight relationship was obtained TW=0.00008 TL 2.38 and showed negative allometric growth. The asymptotic length (Loo) and growth coefficient (K) were estimated at 63 mm and 1.6 per year, respectively. In addition, tmax and t0 were calculated at 1.73 and -0.15 year,   respectively. The von Bertalanffy growth equation was calculated as Lt=63 (1 – e -1.6(t+0.15)). The coefficients of total mortality (Z), instantaneous natural mortality (M), and fishing mortality (F) rates were estimated as 6.65 per year, 2.62 per year, and 4.03 per year, respectively. Size at first capture (Lc) was estimated at 35.67 mm (TL). The current rate of exploitation (E) was given as 0.6 and therefore, the values of exploitation ratio were reasonable for the current fishing effort.

The otolith shape of the Indian halibut, Psettodes erumei, from the Persian Gulf, Hormuz Strait and the Oman Sea were studied to discriminate the fish populations in small-scale fisheries. Indian halibut is a commercially valuable flatfish species abundantly caught in the north of the Persian Gulf and Oman Sea. Identifying different stocks is one of the main issues for fishery management programs. In this study, four otolith measurements (surface area, perimeter, length, and width) and five shape indices (from factor, roundness, circularity, rectangularity, and ellipticity) were recorded. The morphological analyses showed a significant asymmetry between the eyed and blind sides of otoliths. The otolith shape was described by shape indices and then, compared using a canonical discriminant analysis (CDA). The shape indices did not display any significantly different mean values among areas. Also, the patterns derived from CDA did not show any separation among populations. The absence of a disparity in the otolith shape indices could be linked to the similar condition of environment and nutrition in the regions and to the ecological behavior of the species. The results of this study may improve the accuracy of decision-making in the fisheries monitoring and management of P. erumei in the Persian Gulf and Oman Sea.

The present study investigated the potential anti-Omycetes activity of the ethanolic extract of Iranian propolis on two Saprolegnia parasitica isolates (KMG2 and KMG3) obtained from infected rainbow trout eggs in Iran. The initial minimum inhibitory concentration (MIC) of propolis extract was determined by the hemp (Cannabis sativa L.) seed MicroPlate (HeMP) method. Then, the effect of propolis extract on hyphal radial growth and cyst germination was assessed by an agar dilution method and 48-well tissue culture plates, respectively. Also, the impact of propolis on the sporulation activity of Saprolegnia sporangia was evaluated by using Saprolegnia-colonized hemp seed in sterile distilled water (SDW). The HeMP method showed that propolis had some anti-oomycete activity on S. parasitica with a MIC value of 1000 ppm. According to the agar dilution method, complete inhibition of hyphal growth was achieved at 250 ppm for KMG2 and 500 ppm for KMG3. Cyst germination and sporulation activity were ultimately arrested at 200 and 800 ppm, respectively. In conclusion, the propolis extract can be explored as an anti-oomycete substance for treating saprolegniasis in aquaculture. However, an in vivo study is required to assess the safety and efficacy of propolis before application in aquatic animal medicine.