This study was conducted to investigate the effects of different levels of dietary vitamin C on some skin mucus immune parameters, mucus antimicrobial activity and growth performance of Caspian roach (Rutilus rutilus caspicus) fry. Six hundred sixty Caspian roach (1.4 ± 0.02 g) fry were allocated to 12 tanks (55 fish per tank), and triplicate groups were fed diets containing 0, 1,000, 1,500 and 2,000 mg kg(-1) vitamin C for 60 days. At the end of the trial, the epidermal mucus protein level, alkaline phosphatase and antimicrobial activity against two gram-positive bacteria (Streptococcus faecium and Micrococcus luteus) and gram-negative bacteria (Escherichia coli and Serratia marcescens) as well as growth performance were measured. The results demonstrated that feeding on vitamin C significantly elevated skin mucus alkaline phosphatase and protein levels compared to the control group (P < 0.05). However, lysozyme activity was undetectable in both the vitamin C-fed roach fry and the control group. Skin mucus antimicrobial activity was increased following vitamin C administration, and the bacterial growth inhibition zones were significantly elevated in vitamin C-fed roach (P < 0.05). Similar results were obtained in case of the minimum inhibitory concentration of skin mucus. Also fish fed the control diet had a significantly lower weight gain, specific growth rate and condition factor compared to the other treatments (P < 0.05). These results revealed that dietary vitamin C beneficially affects the skin mucus immune parameters and growth performance of Caspian roach fry.

This study aimed to compare histopathological effect of waterborne silver nanoparticles and silver salt (AgNO 3 ) on the gills and liver of Carassius auratus. Therefore, one hundred and five live specimens of goldfish were obtained and treated in five aquariums with 0, 0.01, 0.025, 0.05, and 0.1 ppm of AgNO 3 and 0, 0.1, 0.5, 1, and 5 ppm of Ag nanoparticles (mean particle size of 5 nm). Fish were sampled after 14 days of exposure. Results showed that the kinds of pathologies observed with Ag NPs were broadly of the same type as AgNO 3 including hyperplasia, edema and lifting of the gill epithelium, and lamellar fusion of the gills, and hemosiderosis, hemorrhage, hydropic swelling, and pyknotic nuclei of the liver. Overall, the data showed that although Ag nanoparticles and AgNO 3 pathology were similar, but Ag nanoparticles caused less injury than AgNO 3 in the gills and liver of goldfish. Therefore, it is more proper to use nanoform of Ag in industrials.

1. Overfishing, exacerbated by illegal, unreported, and unregulated (IUU) fishing, is a serious threat to the conservation of the Caspian sturgeon populations, exposing them to the brink of extinction. This indicates the importance of investigating the causes and eliminating the consequences of the occurrence of IUU fishing.2. This study aimed to determine the barriers to sturgeon conservation, and to evaluate the importance of variables involved in the occurrence of IUU fishing in the southern Caspian Sea using field-and questionnaire-based surveys of 520 Iranian fishers and 40 fishery experts.3. Modelling the data using the Logit regression model indicated that several social, economic, conservation, and fishery-related variables (including fisheries knowledge, fish price, fishing method, fishing time, catch/vessel ownership, conservation importance, and penalty awareness) significantly contributed to the occurrence of illegal fishing. Fishers with poorer fisheries knowledge who owned fishing vessels were more likely to be involved in IUU fishing. In addition, fishers who were less concerned about sturgeon conservation and who used non-standard fishing gear at night had a higher probability of committing IUU fishing. 4. Exploring the opinions of fishery experts through the analytical hierarchy process also showed that economic, social, fishing, and conservation criteria were respectively attributed the highest weights as the contributing criteria to the occurrence of IUU fishing. 5. Overall, close associations were observed between the range of determinants, with the probability of the occurrence of IUU fishing indicating that illegal fishing is a complex event that should be studied in different dimensions because of the involvement of a combination of drivers. The knowledge obtained here can assist the relevant agencies in preventing this widespread problem, and with the practical rebuilding and more efficient conservation planning of sturgeon stocks.

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The most important aquatic ecosystems are freshwater rivers, which are considered as biodiversity and drinking water. In this regard, the quantitative and qualitative study of these resources is an important pillar of sustainable development. Gorganroud is one of the most important rivers in northeastern Iran; therefore the aim of this study was to study survey of Gorgnroud River water quality in Golestan Province using Water Quality Index (WQI). For this purpose, five sampling stations were selected along the Gorgnroud River, and samples were taken from April to August of 2015 every 45 days at sampling stations. The parameters of dissolved oxygen, nitrate, nitrite and PH were measured at each turn and the data were analyzed by WQI qualitative index. The results showed that the Water Quality Index at the first station (91/22); at the second station (85/51); at the third station (89.30); at the fourth station (87/14) and fifth station (81/11). The water quality index indicates that water quality of the Gorgnroud River was in a very good quality class during the spring and summer seasons.

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This paper aims to test the suitability of some biotic indices for their application in Southeast Caspian Sea. For this purpose, the ecological quality of the Gomishan lagoon was assessed using three biotic indices (AMBI, BENTIX, BOPA) during summer and autumn 2010. The results from the application of the biotic indices do not highlight a clear distinction between the stations. The results show that two of the indices (AMBI and BENTIX) are very close in terms of diagnosis (good and high) and seem to generally perform better than BOPA. In addition, Principal Component Analysis (PCA) based on abiotic parameters showed clear spatial and temporal differences in environmental variables. However, at this shallow sites with low human pressure and high water residence times, such benthic community composition can be associated with physical stress due to salinity increase and to changes in environmental characteristics, triggered by conventional seasonal variations. Natural variability of transitional waters is a crucial factor for a correct evaluation of the ecological condition of macroinvertebrate communities across the lagoonal system. AbstrAct