DHA and EPA are pivotal for fish physiological functions. This study investigated the effects of dietary DHA+EPA levels on osmoregulation, lipid utilization, and energy metabolism in juvenile black seabream (Acanthopagrus schlegelii) under low salinity environment (5 psu). Different dietary levels of DHA + EPA were formulated (D1 = 10.48, D2 = 18.53, D3 = 25.77, D4 = 31.47, D5 = 38.81 mg/g; DHA/EPA ≈ 1:1) were fed to fish (initial body weight: 15.08 ± 0.02 g) for 8 weeks. Results showed that WG and SGR were markedly higher in D5 group compared to D1. The DHA+EPA contents in liver and muscle were markedly elevated with increasing dietary levels, peaking in D5. Gill expression of osmoregulatory genes (ostf1, aqp1) was markedly downregulated in the D3 group relative to D1, indicating improved osmoregulatory adaptation. Hepatic expression of lipolysis-related genes (atgl, hsl, lpl) peaked in the D2, whereas lipogenesis-related genes (fas, accα), showed the lowest expression in D4. The D2 group also exhibited the highest mRNA levels of mitochondrial energy metabolism-related genes and an increased number of hepatic mitochondria. The D4 group significantly elevated hepatic antioxidants (T-AOC, SOD, GSH-Px, GSH), while D3 showed highest serum T-AOC and SCHR, accompanied by the lowest MDA levels in both liver and serum. Furthermore, hepatic antioxidant gene expression was markedly upregulated at dietary DHA+EPA levels of 18.53–25.77 mg/g. These findings show that moderate dietary DHA+EPA supplementation (18.53–25.77 mg/g) promotes mitochondrial function, antioxidant defense, and osmoregulatory efficiency in juvenile black seabream under low-salinity conditions.
ABSTRACT Biofloc technology (BFT), an eco‐friendly aquaculture system, was evaluated for its effects on growth performance, digestive physiology, gut microbiota, and carcass quality in juvenile common carp (Cyprinus carpio) using cane molasses as a carbon source at carbon‐to‐nitrogen (C/N) ratios of 15, 20, and 25. Compared to conventional intensive farming (control), carp reared in BFT systems (over 90 days) exhibited significantly improved growth performance, including weight gain, specific growth rate, and feed conversion ratio, particularly at C/N ratios of 20 and 25. The BFT groups also demonstrated enhanced digestive enzyme and antioxidant activity, higher proportion of beneficial lactic acid bacteria, and improved carcass composition. These findings indicate that BFT using sugarcane molasses at a C/N ratio of 20 offers a sustainable alternative to conventional carp farming. Beyond improving growth performance, BFT positively influenced fish health indicators and carcass quality.
Oğuzhan Ayaz, Yusuf Şen, İsmail Burak Daban
et al.
Bogue (Boops boops Linnaeus, 1758) is one of the most economic and common species in Türkiye. The bogue individuals were obtained monthly from the commercial catches of gillnet fisheries from May to August 2024 and purse seine fisheries from September 2024 to April 2024 around the Northern Aegean Sea and Southwest Sea of Marmara, Türkiye. The 378 total individuals consisted of 176 females, 201 males and 1 unspecified in the Aegean Sea. The 370 total individuals consisted of 214 females, 154 males and 2 individuals unspecified in the Sea of Marmara. The female:male ratio was calculated as 0.9:1.0 in the Aegean Sea and 1.4:1.0 in the Sea of Marmara. The total length and weight of individuals varied from 10.6 to 28.6 cm (17.52±0.15) and 8.1 to 236.86 g (54.20±2.43) in the Aegean Sea, respectively, and the total length was 10.8 to 28.5 cm (17.92±0.18) and the weight was 13.08 to 399.88 g (76.54±3.14) in the Sea of Marmara. The positive allometric growth was found for females, males and all sexes in both seas. The first maturity length was determined as 12.2 cm TL for females, 15.8 cm TL for males in the Aegean Sea, whereas it was 12.8 cm TL for females, 15.1 cm TL for males in the Sea of Marmara. The reproductive period is estimated between January and May in the Aegean Sea, while February to May in the Sea of Marmara. The total fecundity varied between 2770-85112 (mean:20021±2027) in the Sea of Marmara, while it was 2740-309457 (mean:42834±9194) in the Aegean Sea. As results of this study, some differences were determined in sex ratio, spawning period, and fecundity from the reproductive characteristics between the Sea of Marmara and Aegean Sea. Due to the limited scientific data on the reproductive biology of B.boops in Türkiye, the results of the present study should contribute to the strategic assessment, management, and sustainability of B.boops.
The reflection spectrum produced by a cold medium illuminated by X-ray photons is not isotropic and its shape depends on the emission angle. In the reflection spectrum of an accretion disk of a black hole, the value of the emission angle changes over the disk and, in general, is different from the value of the inclination angle of the disk because of the light bending in the strong gravitational field of the black hole. Current reflection models make some approximations, as calculating a reflection spectrum taking the correct emission angle at every point of the disk into account would be too time-consuming and make the model too slow to analyze observations. In a recent paper, we showed that these approximations are unsuitable to fit high-quality black hole spectra expected from the next generation of X-ray missions. Here, we present a reflection model with improved calculations of the emission angle that solves this problem.
Cristóbal González Díaz, Hector Carrascosa, Guillermo M. Muñoz Caro
In astrochemical exploration, infrared (IR) spectroscopy is vital for understanding the composition and structure of ice in various space environments. This article explores the impact of incident angles on IR spectroscopy, focusing on molecular components present in interstellar and circumstellar ice mantles such as CO, CO$_2$, H$_2$O, CH$_3$OH, NH$_3$, CH$_4$, H$_2$S. The experiment involves changing the angle at which the infrared beam hits the surface used for ice deposition. It is important to measure the density of the ice layer accurately, especially for experiments that involve using different angles in infrared spectroscopy. Furthermore, the experimental methodology allowed us to derive the {\it effective} refraction index values in the infrared range for each ice component. Existing corrections typically consider geometric configurations but overlook the refractive index of the ice ($n$), a factor dependent on ice composition. The study reveals that the incident angle and the refractive index, determine the pathlength of the IR beam across the ice sample. This insight challenges conventional corrections, impacting the integrated absorption values of the IR bands and column densities. In addition, for certain ice components, variations in the incidence angle affect the longitudinal (LO) and transverse (TO) optical modes of the ice, leading to observable changes in the IR band profiles that provide information on the amorphous or crystalline structure of the ice. The practical implications of this work apply to experimental setups where normal IR measurements are unfeasible. Researchers using, for example, the standard 45$^{\circ}$ angle for IR spectroscopy, will benefit from a more accurate estimation of ice column density.
Kelvin E. Vulla, Francis P. Mmanda, Baraka P. Nyangoko
et al.
ABSTRACT Inland aquaculture operations are practised all over the world, contributing about 62.6% of all farmed aquatic animals. This venture is increasing worldwide and outpacing the global market demand for fish and fishery products driven by competition with other animals, over‐population and over‐exploitation of wild capture fisheries. These operations expand globally, associated with the degradation of the culture environment due to poor aquaculture management practices and algal blooms due to nutrient influxes as well as high demand of quality fish feeds of affordable price. To overcome these challenges, sustainable, healthy and environmentally friendly alternatives including probiotics application must be adopted to achieve better production, profitability and productivity as well as a resilient culture environment. In this review, information on potential applications of probiotics in aquaculture (inland aquaculture) focused on sources, safety, approved probiotics for aquaculture, characteristics of probiotics, mode of applications and its potential use on pathogenic microbes control, fish haematological parameters, growth performance and stress responses, water quality parameter, anti‐nutritional factors and feed digestibility, limitation of using probiotics in aquaculture and lastly future perspectives on the probiotics application in aquaculture industry were reviewed and compiled for future sustainable aquaculture production and productivity and environmentally friendly. The review has also highlighted all probiotics application and their approved authority for use in farmed freshwater fish (Nile tilapia Oreochromis niloticus , Catfish Clarias gariepinus , rainbow trout Oncorhynchus mykiss and common carp Cyprinus carpio ) and their cultured environment worldwide. Therefore, the review has comprised all information on the potential benefits application of probiotics in an inland aquaculture for public documentation and also identifies gaps in the aquaculture industry that require further research and assessment.
The objective of this study is to perform an ex-ante assessment of the potential impacts of agro-environmental measures included in the post-2020 Common Agricultural Policy (CAP), by estimating farmers' responsiveness in adopting organic agricultural practices and an eco-scheme that incentivises extensive forage systems. This research is conducted by mean of an Agent-Based Model (ABM), based on Positive Mathematical Programming (PMP), implemented in GAMS. The ABM facilitate the simulation of interaction among farmers, allowing for an analysis of farm heterogeneity. The PMP methodology add a non-rational dimention to the farmers’ economic drivers. The model is calibrated using 2019 Farm Accountancy Data Network (FADN) data specific to the Emilia Romagna region in Italy. Our findings reveal significant impacts on land use, with a notable decrease in cereal cultivation in favour of protein and fodder crops. Moreover, structural shifts are observed, notably a decrease in the number of small-scale farms. We also assess environmental and economic implications, observing a modest reduction in CO2 equivalent emissions per hectare, an increase in water demand, and an overall economic stability among farms, as indicated by changes in gross margin per hectare.
Elizabeth Agyekumwaa, Sefah Joseph Debrah, K. K. Mireku
Although small‐scale fisheries and aquaculture provide opportunities to increase fish yield to supplement rural food and income, they remain undeveloped in Ghana. To contribute towards the development of the sectors, this study sought to assess the biology and ecology of Oreochromis niloticus and Sarotherodon melanotheron in the Brimsu reservoir to provide the requisite information for their management. From the results, mean temperature, dissolved oxygen, pH and transparency of the reservoir were 30.03 ± 0.27°C, 3.78 ± 0.38 mg/L, 8.30 ± 0.21 and 69.79 ± 1.76 cm, respectively. S. melanotheron had a sex ratio of 1:1.36; with mean condition factors of 2.177 ± 0.089 and 2.06 ± 0.029 (p = 0.08) for males and females, respectively. The sex ratio of O. niloticus was 1.45: 1; with mean condition factors of 2.208 ± 0.012 and 2.257 ± 0.014 (p = 0.07) for males and females, respectively. Both species exhibited positive allometric growth with no significant differences between the condition factors for males and females. In addition, there was no significant difference between the sex ratios for S. melanotheron but the number of males of O. niloticus was significantly higher than the females (p ˂ 0.05). Size at sexual maturity (Lm), form factor (a3.0), growth coefficient (K), asymptotic length (L∞) and natural mortality (M) of S. melanotheron were 18.00 cm, 0.020, 0.42 year−1, 30.32 cm and 0.64 year−1, respectively. For O. niloticus Lm, a3.0, K, L∞ and M were 18.57 cm, 0.0223, 0.26 year−1, 38.42 cm and 0.41 year−1, respectively. However, the catch per unit effort for O. niloticus was higher than that of S. melanotheron throughout the study period. The conditions of the reservoir were favourable for the growth of these cichlids. It is recommended that measures should be put in place for the sustainable management and exploitation of fish stocks.
The history of freshwater fish production and consumption in Thailand were reviewed in the late 1970s. While aquaculture had a history of more than a century in the country it had only started to expand relatively recently because of the abundance of wild fish in former times. Historical aspects of freshwater capture fisheries and freshwater aquaculture in Thailand, and the development of irrigation in Central Thailand which played an important role in facilitating the development of inland aquaculture in the country were reviewed. While dam construction led to the demise of the flood plain capture fishery, it provided a controlled water supply necessary for the subsequent development of aquaculture. The study informed the development of education and research in aquaculture at the Asian Institute of Technology (AIT). More recent developments in Thai aquaculture are outlined. Malnutrition in developing countries and fish in the Thai diet at the time of the study were also reviewed.
The rise of aquaculture has been one of the most profound changes in global food production of the past 100 years. Driven by population growth, rising demand for seafood and a levelling of production from capture fisheries, the practice of farming aquatic animals has expanded rapidly to become a major global industry. Aquaculture is now integral to the economies of many countries. It has provided employment and been a major driver of socio-economic development in poor rural and coastal communities, particularly in Asia, and has relieved pressure on the sustainability of the natural harvest from our rivers, lakes and oceans. However, the rapid growth of aquaculture has also been the source of anthropogenic change on a massive scale. Aquatic animals have been displaced from their natural environment, cultured in high density, exposed to environmental stress, provided artificial or unnatural feeds, and a prolific global trade has developed in both live aquatic animals and their products. At the same time, over-exploitation of fisheries and anthropogenic stress on aquatic ecosystems has placed pressure on wild fish populations. Not surprisingly, the consequence has been the emergence and spread of an increasing array of new diseases. This review examines the rise and characteristics of aquaculture, the major viral pathogens of fish and shrimp and their impacts, and the particular characteristics of disease emergence in an aquatic, rather than terrestrial, context. It also considers the potential for future disease emergence in aquatic animals as aquaculture continues to expand and faces the challenges presented by climate change.
In this study, four tributaries (Başpınar, Gölcük, Sukesen and Yavrucak Creeks) of Mogan lake under anthropogenic pressure and declared as a Special Environmental Protection Area were investigated with the following goals: a) Determination of the variations in potentially toxic element concentrations (Cr, Ni, Cu, Zn, As, Cd, Hg, Pb) in the creek waters between different months (December 2002, February 2023, April 2023), b) Calculation of potentially toxic elements indexes (Heavy Metal Pollution Index-HPI and Heavy Metal Evaluation Index-HEI) in terms of irrigation water quality, based on international and national values, c) Determination of the potential ecological risk (PER) status of the creeks in terms of irrigation water quality, d) Comparison of potentially toxic element concentrations with the environmental quality standard values specified in the current “Turkish Surface Water Quality Regulation”. According to the findings; a) In terms of overall potentially toxic element levels, the creeks are ranked as follows: Başpınar Creek> Sukesen Creek>Gölcük Creek>Yavrucak Creek. The heavy metal As was identified as having the highest contribution to metal pollution and the potentially toxic element concentrations in all creeks in February and April were found to be higher compared to that in December, b) The HPI value was found to be less than 15 for all months and creeks, with the highest HPI value of 13.21 calculated in Başpınar Creek in February, c) The HEI values were found to be less than 10 (ranging from 0.02 to 0.84), indicating a low level of potentially toxic element pollution according to this index, d) In terms of irrigation water quality, all creeks exhibited a low level of PER, with the highest PER value of 13.54 belonging to Başpınar Creek, e) The detected potentially toxic element concentrations in all four creeks did not exceed the maximum EQS values provided. In this context, it has been determined that the potentially toxic element levels in creek waters, due to anthropogenic activities, are not currently causing significant pollution. However, it is noted that Başpınar Creek is at a higher risk compared to other creeks. Furthermore, because of the ongoing anthropogenic activities in the basin, long-term metal monitoring studies are important in terms of the sustainability of Lake Mogan.
The Pacific oyster Crassostrea gigas is the most commonly farmed mollusks worldwide, while its production has been hindered by massive mortalities linked to high temperatures. Selective breeding focusing on thermal tolerance is an attractive option for reducing the impact of massive mortalities, but the genetic basis underlying this trait is currently unknown. Hybridization between C. gigas and C. angulata was conducted and followed by one generation of family selection for thermal tolerance. The genetic parameters for thermal resistance, summer survival and growth and selection response were investigated by using 50 full-sibling families. The mean survival of all families ranged from 30.2 to 69.5%, reflecting the large variation of thermal tolerance in the hybrid population. The estimates of heritability for thermal tolerance were low to moderate, ranging from 0.19 ± 0.03 to 0.27 ± 0.05, confirmed that there is genetic basis for thermal tolerance. The phenotypic (r = 0.537, P < 0.01) and genetic correlations (r = 0.546, P < 0.01) between thermal tolerance and summer survival were positive and significant, while the phenotypic and genetic correlations between growth and survival (including thermal tolerance and summer survival) were positive but low (P > 0.05). High response to selection (ΔG = 36.33%) was observed after one generation of selection for thermal tolerance, and there was also corresponding response (ΔG = 14.46%) for summer survival. These results demonstrated that genetic selection to improve summer survival of oyster may be facilitated by selecting highly heat-tolerant lines.
Donald Torsabo, Benedict Terkula Iber, Nurizzati Idris
et al.
This study explores the effects of phospholipid inclusions in the diet of Pangasianodon hypopthalmus young adults on growth and physiological parameters. Commercial diet was subdivided into four groups and top coated using phospholipid (food grade Soy Lecithin) at 0%, 2%, 6%, and 10%, of feed dry weight resulting in an equivalent of 5%, 7.39%, 11.93% and 15.88% total crude lipid levels in the experimental diets. After 90 days of the feeding trials, the phospholipid inclusion at 6% (total crude lipid 11%) significantly improved blood parameters, while inclusion of phospholipid at 10% resulted in a decrease in white blood cells (WBCs) and its associated components, suggesting it may have been above the optimal level required by the fish. Reproductive hormones; 11-ketotestorone and 17β-estradiol that were observed showed an increase in direct proportion following the increase of phospholipid inclusion. Fatty acids composition of the muscle, liver, and gonads show a similar trend with the dominance of C16:0, C18:1n-9, and C18:3n-3 in the tissues. Also, the hierarchy of the fatty acids in the tissues were in the order of SFA > MUFA > PUFA. However, the composition of MUFA decreased with increase in the phospholipid inclusion These findings suggest that dietary phospholipid inclusion can enhance growth and physiological parameters of P. hypopthalmus.
Abstract The Mekong, the largest river in Southeast Asia, is of fundamental cultural, ecological, and economic importance to the entire Mekong region. It supports the highest fish diversity after the Amazon and the largest inland fishery in the world and is at serious threats of intensifying environmental disaster and human activities. Mismatched the high attention worldwide, few related studies were concerning fishes in the whole basin. In this paper, 899 freshwater fish species were recorded, which could be grouped into 9 biogeographical regions based on their distribution information; each region owed its unique fauna with different dominance/or endemism at the genus level. The species richness was positively related to temperature, precipitation, and longitude, but negatively to latitude and slope. Seven migratory systems were deduced from spatial distribution information of 321 migratory species, and these systems were separate but not independent. Mekong fisheries were highly diversified with an estimation of a maximum worth of around $17 billion. Fisheries played an irreplaceable role in Cambodia, and aquaculture was of growing importance in the Delta and the Upper Mekong. Cascade dams, as well as climate change, overfishing, aquaculture, and pollution, posed threats to fish diversity and resources by habitat homogenization, migratory channel blockage, parents population decline, and diseases. Integrated management, a combination of capture and aquaculture fisheries, and collaboration among scientists, fishermen, and the public were advocated to address the issues facing Mekong fishes.