Use of multi-strain probiotics in linseed meal based diet for Labeo rohita fingerlings

Unavailability of probiotics in fish digestive system fingerlings is unable to digest and absorb their food properly. The current research was conducted to investigate the influence of probiotics added Linseed meal based (LMB) diet on hematology and carcass composition of Labeo rohita juveniles. Hematological parameters are essential diagnostics used to estimate the health status of fish. The usage of probiotics for fish health improvement is becoming common due to the higher demand for environment-friendly culture system in water. Linseed meal was used as a test ingredient to prepare six experimental test diets by adding probiotics (0, 1, 2, 3, 4 and 5 g/kg) and 1% indigestible chromic oxide for seventy days. According to their live wet weight, five percent feed was given to fingerlings twice a day. Fish blood and carcass samples (Whole body) were taken for hematological and carcass analysis at the end of the experiment. The highest carcass composition (crude protein; 18.72%, crude fat; 8.80% and gross energy; 2.31 kcal/g) was observed in fish fed with test diet II supplemented with probiotics (2 g/kg). Moreover, maximum RBCs number (2.62× 106mm-3), WBCs (7.84×103mm-3), PCV (24.61), platelets (63.85) and hemoglobin (7.87) had also been reported in the fish fingerlings fed on 2 g/kg of probiotics supplemented diet. Results indicated that probiotics supplementation has a critical role in improvement of fingerlings’ body composition and hematological indices. Present findings showed that probiotics supplementation at 2 g/kg level in linseed by-product-based diet was very useful for enhancing the overall performance of L. rohita fingerlings.

Fatty Acid Composition and Contents of Fish of Genus Salvelinus from Natural Ecosystems and Aquaculture

Fatty acids (FA) of muscle tissue of Salvelinus species and its forms, S. alpinus, S. boganidae, S. drjagini, and S. fontinalis, from six Russian lakes and two aquacultures, were analyzed. Considerable variations in FA compositions and contents were found, including contents of eicosapentaenoic and docosahexaenoic acids (EPA and DHA), which are important indicators of fish nutritive value for humans. As found, contents of EPA+DHA (mg·g−1 wet weight) in muscle tissue of Salvelinus species and forms varied more than tenfold. These differences were supposed to be primarily determined by phylogenetic factors, rather than ecological factors, including food. Two species, S. boganidae and S. drjagini, had the highest EPA+DHA contents in their biomass and thereby could be recommended as promising species for aquaculture to obtain production with especially high nutritive value. Basing on revealed differences in FA composition of wild and farmed fish, levels of 15-17-BFA (branched fatty acids), 18:2NMI (non-methylene interrupted), 20:2NMI, 20:4n-3, and 22:4n-3 fatty acids were recommended for verifying trade label information of fish products on shelves, as the biomarkers to differentiate wild and farmed charr.

Intensive production of the harpacticoid copepod Tigriopus californicus in a zero-effluent ‘green water’ bioreactor

Aquaculture is looking for substitutes for fishmeal and fish oil to maintain its continued growth. Zooplankton is the most nutritious option, but its controlled mass production has not yet been achieved. In this context, we have developed a monoalgal ‘green water’ closed-loop bioreactor with the microalgae Tetraselmis chui that continuously produced the harpacticoid copepod Tigriopus californicus. During 145 days of operation, the 2.2 m3 bioreactor produced 3.9 kg (wet weight) of Tigriopus with (dry weight) 0.79 ± 0.29% eicosapentaenoic acid (EPA), 0.82 ± 0.26% docosahexaenoic acid (DHA), 1.89 ± 0,60% 3S,3’S-astaxanthin and an essential amino acid index (EAAI) of 97% for juvenile Atlantic salmon. The reactor kept the pH stable over the operation time (pH 8.81 ± 0.40 in the algae phase and pH 8.22 ± 2.96 in the zooplankton phase), while constantly removed nitrate (322.6 mg L−1) and phosphate (20.4 mg L−1) from the water. As a result of the stable pH and nutrient removal, the bioreactor achieved zero effluent discharges. The upscaling of monoalgal, closed-loop ‘green water’ bioreactors could help standardize zooplankton mass production to supply the aquafeeds industry.

Organochlorine Compounds in Beached Plastics and Marine Organisms

Here we compare bioaccumulation factors in marine organisms to partition ratios in marine debris for dichlorodiphenyltrichloroethane and polychlorinated biphenyls. Both organochlorines are synthetic persistent organic pollutants emitted into the environment since the beginning of the last century in approximately equal amounts. Their vast use and dispersion have resulted in approximately similar median concentrations of the two organochlorines in some pelagic organisms, namely in the liver and muscle tissue of fish. Molluscs, on the other hand, show higher median uptake of PCBs (median = 2.34 ng/g) than of DDTs (median = 1.70 ng/g), probably reflecting more localized conditions. We found that the bioaccumulation factors can be several orders of magnitude higher than the partition ratios. For instance, the median concentrations of organochlorines in the different matrices of fish, birds, and mammals are between one to four orders of magnitude higher than those found in marine debris, when lipid-normalized; or up to two orders of magnitude when measured as wet-weight. But, in molluscs, bioaccumulation/partition equals unity, which agrees with previous studies using passive samplers. Future research should focus on reducing sources of uncertainty by 1) homogenization of chemical procedures; 2) better assessment of chemical partition equilibrium between water and polymers in environmental conditions; 3) use of (multi)polymer passive samplers better aimed at mimicking uptake of specific living tissues.

Variability in Carcinus maenas Fecundity Along Lagoons and Estuaries of the Portuguese Coast

Although Carcinus maenas as a species is widely studied, research focusing on fecundity is still scarce. The main objective of this study was to evaluate size-fecundity relationships across different lagoons and estuaries, along the Portuguese coast, to understand how the local environment affects reproductive patterns. Between 2019 and 2020, ovigerous females were collected from the Southern (Ria Formosa and Ria de Alvor), Central (Rio Sado) and Northern regions (Ria de Aveiro) of Portugal, and the fecundity of each female was estimated by counting and weighing eggs. Morphometric relationships (carapace width–egg counting; egg counting–egg weight; body wet weight–egg weight; carapace width–body wet weight) were inferred from 180 egg-bearing females with a carapace width between 26.96 and 61.25 mm. A positive correlation between fecundity and the morphological parameters was observed. Differences in fecundity were found among all systems, from northern to southern Portugal, varying between 22121 and 408538 eggs per female. Furthermore, a regional gradient was observed across regions, with lower temperature estuaries (Ria de Aveiro) displaying an increase in fecundity. The fecundity in Rio Sado was also affected by salinity. Fecundity differences across regions were associated with hydrodynamics, temperature, and salinity differences among systems. No statistically significant differences were observed between Carapace Width—Body Wet Weight regressions performed in each studied system, indicating that, contrary to fecundity, the somatic growth of C. maenas is not affected by latitudinal or environmental conditions.

Weight-to-weight conversion factors for benthic macrofauna: recent measurements from the Baltic and the North seas

The availability of standardised biomass data is essential for studying population dynamics, energy flows, fisheries and food web interactions. To make the estimates of biomass consistent, weight-to-weight conversion factors are often used, for example to translate more widely available measurements of wet weights into required dry weights and ash-free dry weight metrics. However, for many species and groups the widely applicable freely available conversion factors have until now remained very rough approximations with high degree of taxonomic generalisation. To close up this gap, here for the first time we publish the most detailed and statically robust list of ratios of wet weight (WW), dry weight (DW) and ash-free dry weight (AFDW). The dataset includes over 17 000 records of single measurements for 497 taxa. Along with aggregated calculations, enclosed reference information with sampling dates and geographical coordinates the dataset provides a broad opportunity for reuse and repurposing. It empowers the future user to do targeted sub-selections of data to best combine them with their own local data, instead of only having a single value of conversion factor per region. The dataset can thereby be used to quantify natural variability and uncertainty. The dataset is available via an unrestricted repository from https://doi.org/10.12754/data-2021-0002-01 (Gogina et al., 2021).

The Role of Growth Regulators in The Multiplication of Stevia Rebaudiana Bertoni Shoot and Callus Induction in Vitro

The research was conducted to investigate the effect of plant growth regulators on the vegetative multiplication of the Stevia plant shoot and the induction of callus from it. The results indicated that the interaction between 2.0 mg. L-1 BA with 0.5 mg. L -1 Kin gave the highest rate number of shoot with 6.32 branches and the highest average of leaves number Were 9.60 leaves compared to the lowest average for the number of shoot and leaves Were 1.40 shoot and 3.80 leaves respectively. As for the length of the shoot, the interaction between (1.0 mg. L-1 BA and 0.5 mg. L-1 Kin) gave the highest average shoot length 4.31 cm compared to the control which gave 2.20 cm. in connection with the callus induction, the concentration 3 mg. L-1 of NAA gave the highest percentage of callus induction from leaves 100%, and the lowest mean of days that for callus initiation was 9 days compared to the control which reached to 20 days. As for the wet and dry weights of callus tissue, the interaction between 2.0 mg. L-1 NAA and 0.5 mg. L -1BA gave the highest wet weight rate 3.68 g and the average dry weight was 0.31 g compared to the control which gave the lowest rate 0.95 g, 0.08 g respectively.

Trophic ecology of Patagonian flounder Paralichthys patagonicus (Jordan, 1889) in the Argentine-Uruguayan Coastal Ecosystem

Food habits and diet composition of Patagonian flounder Paralichthys patagonicus (Jordan, 1889) were studied on the basis of stomach content analyses from 828 specimens (512 females, 304 males, 12 unsexed) collected during 16 commercial cruises between February 2009 and April 2010 in the Argentine-Uruguayan Coastal Ecosystem (34° S-41° S). A total of 272 stomachs (32.9%) contained food (184 females and 84 males), among which 20 prey taxa were identified. The most important prey category was pelagic fish, primarily Argentine anchovy (Engraulis anchoita), followed by rough scad (Trachurus lathami). Evidence showed that females consumed a higher total wet weight of prey compared to males. Results also suggested a specialised diet over E. anchoita, across all sex and size groups. The estimated trophic level for the population of P. patagonicus was 4.16. This study suggests that P. patagonicus is a tertiary piscivorous consumer of the trophic food web in the region, and reveals changes in the prey consumption compared with previous studies.

Changes of Rat Embryon Nephrogenesis during Cadmium Salt Intoxication in Pregnant Females

The purpose of the experimental study was to determine morphogenetic disorders of embryonic and fetal kidney development in chronic intragastric exposure to cadmium salts (cadmium chloride, cadmium citrate) in pregnant females. Materials and methods. Low doses of cadmium salts were selected for the study, which can be compared with the actual concentration of cadmium in the daily diets of women, including pregnant women, in industrial regions. In the experiment, female rats with a given gestational age were divided into groups as follows: Group 1 – control (number of females – n = 16, of which 8 left the experiment on the 13th day of pregnancy, and 8 on the 20th; the number of embryos – n13 = 76; n20 = 77); Group 2 – administration of cadmium chloride at a dose of 1.0 mg/kg body weight of the female (number of females – n = 16; number of embryos – n13 = 65; n20 = 62); Group 3 – administration of cadmium citrate at a dose of 1.0 mg/kg body weight of the female (number of females – n = 16; number of embryos – n13 = 69; n20 = 70). Results and discussion. New quantitative data on the effect of cadmium salts were obtained on the thickness of the cortical and cerebral layers of the kidneys, the diameter and area of the cavity of the nephron capsule in the prenatal period of development in chronic female intoxication. On the 13th day, the effect of cadmium salts on the development of embryonic kidneys was multidirectional: the effect of cadmium chloride led to an increase in the thickness of the mesonephros and mesonephric duct, and the effect of cadmium citrate reduced the studied parameters. On the 20th day of rat embryogenesis in the group exposed to cadmium chloride, the renal weights increased, and when exposed to cadmium citrate, the weight of the kidneys decreased significantly (p˂0.05) both in comparison with control values and in the group exposed to cadmium chloride. On the 20th day of development, in order to exclude an error in estimating the dynamics of changes in the weight of embryo mass and kidney mass, the nephrofetal index was calculated, i.e. the ratio of wet kidney mass to wet weight of fixed fetus. Histological parameters of nephron diameters were also compared. Conclusion. Cadmium citrate has been shown for the first time to be less non-photoxic than cadmium chloride. Calculation of the area of the cavity of the nephron capsule by the spline contour method showed a 2.6-fold decrease in the average area of the capsule cavity in the group exposed to cadmium chloride relative to the control mean values, indicating a violation of nephrogenesis. When exposed to cadmium citrate, there was also a decrease in the area of the cavity of the nephron capsule by 1.8 times, which indicates a lower level of nephrotoxic cadmium citrate compared to cadmium chloride, despite the identity of the dose of exposure

A Multi-Species Investigation of Sponges’ Filtering Activity towards Marine Microalgae

Chronic discharge of surplus organic matter is a typical side effect of fish aquaculture, occasionally leading to coastal eutrophication and excessive phytoplankton growth. Owing to their innate filter-feeding capacity, marine sponges could mitigate environmental impact under integrated multitrophic aquaculture (IMTA) scenarios. Herein, we investigated the clearance capacity of four ubiquitous Mediterranean sponges (Agelas oroides, Axinella cannabina, Chondrosia reniformis and Sarcotragus foetidus) against three microalgal substrates with different size/motility characteristics: the nanophytoplankton Nannochloropsis sp. (~3.2 μm, nonmotile) and Isochrysis sp. (~3.8 μm, motile), as well as the diatom Phaeodactylum tricornutum (~21.7 μm, nonmotile). In vitro cleaning experiments were conducted using sponge explants in 1 L of natural seawater and applying different microalgal cell concentrations under light/dark conditions. The investigated sponges exhibited a wide range of retention efficiencies for the different phytoplankton cells, with the lowest average values found for A. cannabina (37%) and the highest for A. oroides (70%). The latter could filter up to 14.1 mL seawater per hour and gram of sponge wet weight, by retaining 100% of Isochrysis at a density of 105 cells mL−1, under darkness. Our results highlight differences in filtering capacity among sponge species and preferences for microalgal substrates with distinct size and motility traits.