International Journal of Aquatic Biology
Volume:10 Issue: 1, Feb 2022

Microplastics are threatening to public and environmental health for their potential toxicity. Thus, understanding the ecological occurrence of MPs is crucial, but research on MPs in Bangladesh has yet in its infancy. To understand the existence of MPs in aquaculture, we investigated fish flesh, commercial fish feed, and rearing water of Heteropneustes fossilis farms (n = 10). The density separation method to extract and light microscopic technique to analyze the MPs were employed. A total of 191 MPs particles were recorded, whereas 134 in rearing water ranging from 8-53 μm, 45 in fish feed ranging from 10-88 μm, and 12 in fish flesh ranging from 7-15 μm. Fiber type MPs were the most frequent, contributing 77% in water, 62% in fish feed, and 5% in fish flesh, following fragments and films. Identified MPs were obtained with various colors such as black, blue, brown, translucent, and mixed. MPs were found with the highest abundance in the fish feed (6 particles gm-1), subsequent in water and fish flesh. Identifying the sizes, shapes, colors, and types of MPs is crucial as it affects the interaction and uptake in fish. This study provides an important baseline for future research on the transfer of MPs via the food chain.

The purpose of this study was to investigate the catch trend and estimation of the optimized catch limit of the Scomberomorus guttatus (GUT) stock by collecting catch data in southern Iranian waters. In this study, two methods were used to determine the biological reference points (BRPs) of Indo-Pacific king mackerel in southern Iranian waters i.e. the Persian Gulf and Oman Sea. Catch data was collected for 23 years (1997-2019), and the optimized catch limit was estimated using a limited data approach and R Software. The average catch (Ct) for this period was 5123 tonnes (95% confidence interval 4026 -6218 tonnes), and it had significantly increased over the past two decades. The average (maximum-minimum) of carrying capacity (K), maximum sustainable yield (MSY), the biomass of maximum sustainable yield (Bmsy), current biomass (B) and fishing mortality of maximum sustainable yield (Fmsy) were obtained by the Depletion-Based Stock Reduction Analysis (DBSRA) and Catch- maximum sustainable yield (Cmsy) models. The Bmsy and K in two models showed no significant difference from the one-sample t-test at P>0.05. The results revealed that the exploitation ratio in the Indo-Pacific king mackerel stock is full fishing (full exploitation), and do not suggest an increase in exploitation ratio and fishing effort are proposed.

Sulfate-reducing bacteria (SRB) exist in anaerobic environments, such as marine sediments, and produce hydrogen sulfide, which is toxic to marine animals. However, little is known about the ecology of SRB in the gut of fish. In the present study, we used molecular techniques to analyze the predominant SRB community in the gut of pufferfish inhabiting coastal areas of Japan. The density of the dissimilatory sulfite reductase alpha gene, dsrA, derived from SRB and total count of bacteria in guts of pufferfish was 4.4×106 - 1.8×107 copies/g and 3.5×108 - 6.3×109 cells/g, respectively, in all specimens. Clones of dsrA associated with Desulfobulbus oligotrophicus, a dominant SRB species, were detected in all 12 libraries, accounting for 57.7-94.3% of clones in each library. These results strongly suggest that SRB are indigenous bacteria in the gut of pufferfish and that hydrogen sulfide produced by SRB may be a risk factor for fish health.

Many ecological studies deal with a multivariate approach in the statistical analysis of the data. Aquatic ecologists advise applying the multivariate techniques to interpret environmental data information through various techniques such as biplots plotting in PCA, RDA, and CCA to achieve this goal. This work examines the importance of the application of the preparation of raw data before performing the statistical techniques in terms of scaling and transforming data and its important impact on the results of the PCA analysis of the water quality. The results showed the effect of data processing on the outputs of the analysis. However, raw data must be presented to evaluate appropriate methods of data processing before applying analysis techniques. The results of the study showed that some data did not show a clear change when converting their raw data, while other variables had a significant and clear effect on improving the normal distribution of values after the conversion of raw data, and this was evident through the Shapiro–Wilk test which was conducted for the variables where the values increased significantly.

In an attempt to elucidate the Vibrio inhibitory activity of saline tilapia green water, we have isolated Bacillus subtilis BF12, exhibiting potent secreted antibiotic effects against Vibrio parahaemolyticus. We tested B. subtilis BF12 pathogenicity to Penaeus monodon and its efficacy to protect the shrimp against V. parahaemolyticus infection. The results indicate that B. subtilis BF12 is not pathogenic to shrimp since no mortalities was observed in all treatment groups. The feeding trial shows that shrimp in the treated group exhibited higher survival and improved growth performance. The infection challenge test with pathogenic V. parahaemolyticus administered orally indicates that the group receiving the probiotic has significantly higher survival rates. Lower counts of V. parahaemolyticus in the gut of the probiotic treated group were also recorded. Collectively our results indicate that the application of probiotic B. subtilis BF12 is an effective, practical and applicable means to prevent V. parahaemolyticus infection in P. monodon culture.

The larviculture of fish and shellfish is inevitably dependent on live food such as Artemia and one of the most important issues in rearing Artemia is the food supply. Artemia culture is mainly dependent on freshly prepared unicellular algae, which is not accessible easily. This research focused to prepare a dry feed that can support the survival and growth of Artemia and improve its resistance against pathogenic bacteria. The nauplii of Artemia were fed seven feeding treatments, including the control diet (algae + yeast) and six experimental dry feed containing different levels of probiotic bacteria. The results showed that Artemia fed a diet containing 10% algae+1.25% probiotic bacteria performed slightly better in terms of growth, but significantly higher survival and increased alkaline protease activity was detected compared to control. The lipase activity was significantly higher only in Artemia fed 5% algae + 0.625% probiotic bacteria, and the highest Amylase activity was detected in the control group. The activity of the antioxidant enzymes superoxide dismutase (SOD), Glutathione reductase (GRed), Glutathione peroxidase (GPx) and Malondialdehyde (MDA) presented a significant increase as a function of culture time and probiotic administration. The challenge with the pathogen resulted in significantly higher survival in all tested life stages of Artemia (nauplii, juvenile, and adults) in negative and positive controls compared to the control diet group. It is concluded that pathogen induces an oxidative stress response in almost all stages of Artemia growth and probiotic bacteria Bacillus coagulans and B. subtilis protects Artemia when challenged with Vibrio anguillarum by enhancing immune responses.

A revised list of Cystoseira species in Algerian coasts is established in this study. Eighteen taxa at specific and infraspecific levels accepted for Algeria are inventoried from updated literature and personal investigations. We report for the first time the presence of Cystoseira humilis var. myriophylloides (Sauvageau) J.H.Price & D.M.John on the Algerian coast.

Aquatic mcroinvertebrates are important members of freshwater ecosystems and most of them are arthropods. This study aimed to study the arthropod diversity in Shatt Al-Kufa. Samples were collected monthly from four sites in Euphrates River in Najaf city (Shatt al-Kufa) from March 2020 to April 2021. Based on results, 10 mcroinvertebrates taxa were found. Arthropoda were at their highest densities in spring, with Chironomus being a dominant species. In spring, the Shanon-Weiner diversity and Species Richness indices were recorded higher. Based on the results, the Shatt al-Kufa was moderately diverse in spring. There were significant differences between seasons and study sites in terms of the density and diversity of aquatic insects.

This study was conducted to investigate the effect of birth sequence and gender of newborns on milk production and its components in Iraqi buffaloes. A total of 210 raw milk samples were used from 70 female buffaloes at different ages, breastfeeding young of different sexes. The result showed a significant effect of the birth sequence on daily milk production, where the group of mothers with the fourth birth sequence and more was significantly had higher production. The mothers with the second birth sequence significantly outperformed the mothers with the first birth sequence. The highest daily milk production was in the fourth birth sequence group and more and the lowest in the first birth sequence group (11.14±0.165 vs. 3.74±0.198kg). The effect of the birth sequence was significant (P<0.05) on the percentage of total solids, fat percentage, and milk density. The results showed a significant effect of the newborn gender on daily milk production, total solids, and the density of milk, where the mothers of male births had the higher daily milk production (8.74±0.328 vs. 6.40±0.328kg), while the mothers of female births had a significantly higher percentage of total solids and milk density.