International Journal of Aquatic Biology

The use of different otolith-shape analyses for stock discrimination of Yellowtail Snapper Ocyurus chrysurus, (Bloch, 1791) in the coastal waters of northeastern Brazil

2023-03-07T00:23:12+00:00

In this study, the otolith morphology of yellowtail snapper (Ocyurus chrysurus) was used for stock identification based on different shape analyses viz. morphometric parameters with shape indices, Elliptical Fourier descriptors (EFD), wavelet transform (WT), and landmarks. The samples were collected from Fortaleza (Ceará) and Recife (Pernambuco) in the coastal waters of Brazil to identify stocks and determine the best method for stock discrimination of O. chrysurus. The result showed no significant difference between these two regions which was supported by the Linear Discriminant Analysis (LDA). To select the best discrimination methods a correct classification through jack-knifed and Wilks’ ? test was performed. The morphometric parameters with shape indices showed a correct classification of 25% and the landmark method's correct classi?cation was 33.1%. These two methods had a lower correct classi?cation than the otolith contouring methods (EFD = 42.3% and WT = 43.5%). Also, the Wilks’ ? test showed lower power discrimination for morphometric with shape indices and landmark method (?= 0.904 and ?= 0.808, respectively), in comparison with the two contouring methods (EFD ? = 0.688 and WT ? = 0.601). These results indicate that the most suitable methods for observing small variations in O. chrysurus otoliths can be EFD and WT.

Population structure of the European anchovy, Engraulis encrasicolus (Linnaeus, 1758) in Lake Manzala, Egypt

2023-04-12T19:02:36+00:00

The present study is to identify the population and stock characteristics of Engraulis encrasicolus in the Mediterranean lagoon “Lake Manzala” of Egypt. A total of 1536 specimens were collected seasonally by a local trammel net (El-Balla), from 2019 to 2021. The length ranged from 4.2 to 12.1 cm, where the dominance was of medium sizes. Two age groups were observed with a short longevity (t_max= 3.16 y). Parameters of Von Bertalanffy, L_?, and K, were estimated as 12.52 cm and 0.95 y^-1, respectively. The growth performance index (Ø) was estimated as 2.17, expressing liner growth and environmental suitability. The calculated length at first maturity (L_m) = 8.1 cm, compared to 6.9 cm of length at first capture (L_c), expressing high fishing effort. Mortality indices include: total mortality (Z) = 3.71 y^-1, and natural mortality (M) = 1.46 y^-1. According to biological reference points, F_opt = 0.73 y^-1 and F_limit = 0.97 y^-1, the fishing mortality (F = 2.25 y^-1) indicated overfishing of the anchovy stock in Lake Manzala. The current exploitation rate, E = 0.61 expressed the occurrence of overexploitation. Based on the results, reducing fishing efforts is vital to maintaining stock stability.

Effect of coconut (Cocos nucifera) water, and aqueous extract of Mung bean (Vigna radiata) sprouts and Moringa (Moringa oleifera) leaf on the growth and nutrition of Caulerpa racemosa

2023-10-29T23:51:31+00:00

Caulerpa racemosa, or sea grape, has a high nutritional content and offers many health benefits to humans. The problem faced in cultivating sea grapes is growth, which affects production. This study aimed to determine the effect of different times of soaking C. racemosa in (Cocos nucifera) water, and aqueous extract of Mung bean (Vigna radiata) sprouts and Moringa (Moringa oleifera) leaf on its morphology and growth performance. Fifty grams of C. racemosa was soaked in coconut water and an aqueous extract of moringa leaves and mung bean sprouts at different times and was cultivated for 30 days. This study used a complete randomized design (CRD) with four treatments and three replicates: A (without soaking), B (extracts of Mung bean sprouts and Moringa leaves soaked for 2 hours), C (crude extracts of Mung bean sprouts and Moringa leaves soaked for 4 hours), D (coconut water soaked for 40 minutes), and E (coconut water soaked for 50 minutes). The results showed that the soaking process of C. racemosa in coconut water and aqueous extract of moringa and mung bean sprouts significantly affected the growth and nutrition of C. racemosa. Caulerpa racemosa soaked in coconut water for 40 minutes showed the highest absolute growth (206.66±7.96 g), specific growth (5.45±0.10 %/day), protein (9.11±0.29%), and fiber (1.02±0.20). The morphology of C. racemosa showed that the ramulli, rhizoid, fronds, and stolon were fresh, healthy, and clean. Soaking sea grape seeds in natural PGRs can increase the growth, production, and nutritional content. Further research can be conducted, such as identifying the bioactive substance and its amount in coconut water.

The concentration of some heavy metals in different parts of reed plant Phragmites australis, along the Al-Sabeel River, Iraq

2023-12-30T21:10:41+00:00

The present study was conducted to determine the concentrations of some heavy metals of lead, cadmium, and chromium in the roots and stems of Phragmites australis collected from the Al-Sabeel River in Iraq. Samples were collected at four selected sites in three provinces of Najaf, Diwaniyah, and Samawah over a distance of 114 km, from August 2022 to January 2023. The results reveal that the concentrations of Pb, Cd, and Cr in the roots and stems of the reeds as 134.28-91.21, 189.47-180, and 190.57-97.9 mg/kg dry weight, respectively. Cr was the most accumulated element in the stem, while Cd was the most accumulated in the roots. The results also showed that the stem accumulates heavy metals more than the roots, indicating the possibility of using the reed as an indicator of heavy metal pollution.

Physiological properties of a new strain of Saccharomyces cerevisiae Dag-1 isolated from the Caspian Sea, Russia

2023-11-19T07:27:39+00:00

This study reports the isolation of the yeast Saccharomyces cerevisiae Dag-1 (OQ107063.2) from the seawater of the Caspian Sea, specifically from the coastal territory of the Samursky Reserve, Republic of Dagestan, Russia. The strain’s diagnostic and genetic characteristics are provided. Morphological features of the S. cerevisiae Dag-1 include round cells measuring 5.0×5.0 and 1.0×1.0 µkm in size. On Sabouraud’s media, it forms round, convex, opaque, creamy, glossy colonies with a diameter of 3-5 mm. The isolated strain demonstrates the ability to thrive in seawater with a salinity ranging from 12.8-13.0‰, across various temperature ranges (0 –+10, 23-28, 35-40, 30-37°C), and under different pH conditions (5.6; 8.4-8.5). Additionally, it utilizes monomeric sugars (L-glucose, D-mannose, D-sucrose, D-arabinose, D-cellobiose, and D-xylose) as a source of carbon and energy, also metabolizing alcohols such as D-sorbitol, D-mannitol, and D-inositol (vitamin B8). The strain does not absorb the amino acids lysine and ornithine, and it is catalase-, amylase-, and ?-glucosidase-positive while being urease-, oxidase-, and ?-galactosidase-negative. Moreover, the strain exhibits high sensitivity to the antibiotics of ketoconazole, nystatin, clotrimazole, fluconazole, and itraconazole. Resistance is observed against the inhibitor potassium tellurite and pathogenic bacteria Escherichia coli, Staphylococcus aurens, and Klebsiella oxitoka. These findings contribute to expanding our understanding of the ecological distribution of marine yeasts and the isolation of an S. cerevisiae strain possessing characteristics of industrial microorganisms.

Gut content, feeding behavior, and gut microbiome of Pangasius nasutus (Bleeker, 1863) in natural habitat and captivity environment: A review

2023-10-27T15:44:10+00:00

Pangasius nasutus is a freshwater fish that has become one of the major economic sources for fish farmers in Pahang River, Malaysia. Effective aquaculture and conservation P. nasutus depends on the understanding of their gut composition, feeding habits, and gut microbiome. Pangasius nasutus in their natural habitat mostly consume a variety of food sources, including zooplankton, aquatic insects, and crustaceans. The advances in metagenomic sequencing technologies have made it possible to examine gut bacteria by examining hypervariable areas of 16S rDNA for prokaryotes and 18S for eukaryotes through cloning and transferring biologically produced DNA into a bacterial host. In recent times, significant attention has been directed towards nutritional manipulation and the modification of gut microbiota to align with the requirements of aquaculture, all the while aiming to preserve the health and welfare of the host. This paper intends to review the gut content and feeding behavior of Pangasius sp. that will be contributed to the local fish farmer for their breeding and production of high-quality P. nasutus in a short period of time.

Effects of thermal treatment of some dietary feed ingredients on their digestibility and growth of common carp, Cyprinus carpio fingerlings

2024-01-05T12:39:02+00:00

The purpose of the current study was to determine the effects of thermal treatment (autoclaving) of several dietary feed ingredients, including fishmeal, soybean meal, wheat bran, yellow corn, and barley, on the apparent digestibility coefficients ADCs, as well as the growth and feed efficiency of common carp, Cyprinus carpio fingerlings. The feed ingredients were autoclaved for 10 min at 121ºC and 15 psi in a laboratory autoclave. Two experiments were conducted, the first consisted of 11 diets, reference, and 10 experimental diets (reference was mixed with each raw or autoclaved test ingredient in a ratio of 70:30) to determine the digestibility of feed ingredients. The second experiment consisted of 8 diets, a control diet of raw ingredients and seven experimental diets were formulated, five of them in which one of the raw feed ingredients was replaced with the autoclaved one, the sixth in which three raw ingredients (wheat bran, yellow corn, and barley) were replaced together with the autoclaved ones, and the seventh in which all the raw ingredients were replaced with the autoclaved ones. The results of the first experiment presented that autoclaving significantly enhanced ADCs of dry matter, protein, and energy, of all feed ingredients except fishmeal. The results of the second experiment similarly presented that the thermal treatment significantly enhanced ADCs in the diets containing autoclaved soybean meal or wheat bran, yellow corn, and barley or all ingredients compared control diet. The growth and feed efficiency were better significantly in autoclaved soybean meal or all ingredients diets compared control diet. It is advised that plant-based ingredients, especially soybean meal, be thermally-processed to improve their nutritional value and lessen their environmental impact.

Effect of Tetraselmis suecica microalgae isolated from the Persian Gulf on the expression level of AKT/mTOR genes in the liver cancer cell line, Huh7

2023-08-13T08:06:29+00:00

The medicinal and therapeutic properties of microalgae, especially their anti-cancer properties in modulating cellular mechanisms such as cytotoxicity, reducing tumor cell invasion, and increasing apoptosis, have drawn attention to their therapeutic application in cancer. However, there are few reports on the effects of Tetraselmis suecica microalgae on liver cancer. As the aim of this study, after ethanolic extracting from T. suecica, and IC50 determination, the effect of T. suecica microalgae extract on cytotoxicity and apoptosis of Huh7 cells was investigated by MTT and Annexin V/PI staining, respectively. In addition, the expression of AKT/mTOR genes was measured by real-time PCR test. Based on the results, ethanolic extract of T. suecica to the Huh7 cell line significantly decreased the expression of AKT and mTOR genes compared to the control group. The vitality of cancer cells in concentrations of 500 and 1000 µg/ml of T. suecica extract in a 48-hour culture, decreased significantly. In addition, in the 72-hour treatment, a significant decrease in cell viability was observed in the concentrations of 250, 500, and 1000 ?g/ml. According to the results, T. suecica microalgae can offer good benefits as valuable natural materials for the pharmaceutical industry, especially anticancer drugs.

Induction of precocious sex reversal in aquaculture: effects of methyltestosterone treatment on gonadal sex of yearling longtooth grouper (Epinephelus bruneus)

2023-11-23T01:55:17+00:00

Groupers, highly valued fish globally, exhibit sex change from female to male during adulthood, posing challenges in obtaining wild males for aquaculture. Inducing female-to-male sex reversal in juvenile groupers can streamline breeding efforts. This study used 17a-Methyltestosterone (MT)-loaded cholesterol pellets to treat one-year-old longtooth groupers (Epinephelus bruneus) and induce small functional males. Gonadal sexuality and male functionality were assessed after one to two months. Initial gonadal changes included efferent duct differentiation. High-dose MT-treated fish exhibited active spermatogenesis. However, no spermiation was observed. This highlights MT's potential for sex reversal but not for complete testicular function. These findings have implications for grouper aquaculture and the management of sex change. Further research should explore methods to optimize functional male induction for sustainable breeding practices.

Seasonal dynamics of heavy metal uptake in some aquatic plants of the Tigris River

2024-01-15T21:33:56+00:00

This work aimed to study the accumulation of heavy metals Cadmium, Lead, Chromium, and Nickel in different aquatic plants along the Tigris River. The research focused on the seasonal variations in heavy metal uptake by Phragmites australis, Typha domingensis, Persicaria salicifolia, Azolla filiculoides, and Ceratophyllum demersum. Samples were collected from three distinct locations along the river, each characterized by varied environmental conditions. Using Atomic Absorption Spectrophotometry, the quantified metal concentrations were measured, revealing significant differences across seasons and locations. The study provides crucial insights into the dynamics of heavy metal accumulation in riverine ecosystems, underscoring the role of environmental factors and plant species in metal uptake.

Main pathways for microplastics in freshwater systems: A review on potential sources and drivers of microplastic pollution in rivers

2022-06-17T18:04:05+00:00

Microplastics are ubiquitous in surface waters and sediments of freshwater systems. Reports of MP presence in high concentrations, even in remote regions, indicated that this emerging pollutant can be a serious problem for environmental health. Because of their diverse sources, tracking and identification of all entry routes of MPs into freshwater rivers remain unknown. Investigation of drivers of MP concentration and distribution in these systems can help reach a point of view about the potential sources of these particles. In this review, more than 100 documented papers about MP particles and their presence in surface waters and sediments of different freshwater systems (with a focus on rivers) were investigated. MP pollution in a river can be due to anthropogenic factors including point and non-point (diffuse) sources of MPs. In this regard, wastewater treatment plants are the most investigated point source of MPs. However, there is much less investigation on other point sources such as industrial wastewater. The most important diffuse sources of microplastics are urban land-use, which consists of various sources such as domestic sewage (point) and road runoff (non-point). Agricultural land-use as a diffuse and important source of MPs is also less studied in the literature. Water hydro dynamic (e.g. surface currents and stagnant water zones) and seasonal variability (e.g. rainfall) are important factors in MP distribution in rivers. Physio-chemical characteristics of MPs (including shape, size, color, and chemical composition) can serve as indicators of potential sources of particles; and are effective in MP distribution in riverine systems. It should be noted that freshwater rivers can be considered as both sink and source for MPs.

The first record of Koi fish, Cyprinus rubrofuscus, from a natural waterbody in the Hormuz basin, southern Iran

2024-01-26T16:54:13+00:00

The number of exotic freshwater ornamental fish species released from the aquarium trade in Iran has been increasing in recent years. The Koi fish has already been reported from Iran, where it occurred in the southern Caspian Sea and Namak Lake basins. This is the first documented record of Cyprinus rubrofuscus from the Hormuz basin in southern Iran, which shows the range extension of this species in Iran. It seems there is no natural predator in most of the Iranian aquatic ecosystems for large Koi specimens. Therefore, the establishment of established populations in the natural lentic habitats is probable. Hence, eradication programs need to be accompanied by a public awareness campaign to ensure that the aquarium trade and hobbyists do not release these pet fishes into natural habitats.