Effects of the dietary supplementation of copper on growth, oxidative stress, fatty acid profile and skeletal development in gilthead seabream (Sparus aurata) larvae

The effect of dietary copper (Cu) levels on growth, oxidative stress, fatty acid profile and bone health of gilthead seabream larvae (Sparus aurata) was studied in 47 days-post-hatching fish fed 4 experimental diets containing 17, 18, 19 and 25 mg Cu/kg diet. After 21 days of feeding, larval growth and survival were not affected by the dietary Cu levels. However, larvae fed the non-supplemented diet (17 mg Cu/kg) showed clear symptoms of Cu deficiency, including increased lipid peroxidation and reduced bone mineralization. Increased peroxidation risk caused a reduction in essential fatty acids and n-3 PUFA (polyunsaturated fatty acids) contents in whole body lipids, whereas the poor vertebral body mineralization in seabream larvae was related to a marked increase in abdominal vertebrae anomalies. On the contrary, dietary Cu supplementation raised whole-body contents in DHA, EPA and n-3 PUFA and reduced MUFA, TBARS and the incidence of severe, cranial, branchiostegal rays and abdominal vertebral anomalies. Polynomial regression models applied to all these parameters suggested optimum dietary Cu levels to be 21.5–22.6 mg/kg in gilthead seabream larvae microdiets supplemented with CuSO4.5H2O. These levels (21.5–22.6 mg/kg) are in the range of the Cu contents in copepods (12–38 mg/kg) and on the verge of the dietary levels authorized by EU Commission in feeds for cultured fish species (25 mg Cu/kg diet).publishedVersio

Effect of Polystyrene Microplastics in Different Diet Combinations on Survival, Growth and Reproduction Rates of the Water Flea (Daphnia magna)

Microplastic pollution is a problem not only in the marine environment but also in freshwater ecosystems. Water flea (Daphnia magna) is one of the most common omnivorous cladocerans in freshwater ecosystems. In this study, the potential effects of microplastics (fluorescent polystyrene beads with dimensions of 6 microns) on the survival, growth and reproduction of Daphnia magna were examined during 21 days of laboratory experiments. Microplastics (MPs) were observed to be ingested alone or along with either the microalgae Chlorella vulgaris (Cv) or baker’s yeast (By). D. magna fed exclusively with microplastics showed a drastic decline in survival similar to that in the starving group. The least growth in total length or width was observed in Daphnia specimens fed only MPs and the starved groups. Daphia fed with a mixture of MPs/Cv or MPs/By produced a significantly (p < 0.05) lower number of ephippia. Our results show that high concentrations of microplastics adversely affect Daphnia magna populations

The effect of feeding with different microalgae on survival, growth, and fatty acid composition of Artemia franciscana metanauplii and on predominant bacterial species of the rearing water

Artemia franciscana metanauplii widely is being used in cultured marine species. The aim of this study was to evaluate the effect of feeding with two marine and two freshwater microalgae as feed alone or in combination on survival, growth, and fatty acid composition of A. franciscana metanauplii and on predominant bacterial species of the rearing water. Five microalgae diets were used for feeding: Amphora viridis (AV), Chlamydomonas reinhardtii (CR), Chlorella vulgaris (CV), and Dunaliella salina (DS) and a combination of four microalgae (MX diet). Artemia franciscana fed AV, DS, and MX diets showed higher survival than that fed CR and CV diets. MX group showed higher total length among groups (P < 0.05). Total n-3 fatty acid content was higher in the Artemia franciscana fed MX group, whereas total n-3 HUFA levels were found significantly higher in Artemia franciscana fed DS and AV diet (P < 0.05). The bacterial load of the rearing water was significantly decreased with the use of CV; therefore, the CV diet might be suggested to be used in Artemia franciscana grow-out for reducing bacterial proliferation. According to 16S rRNA gene sequencing results, four different bacterial species including Carnobacterium maltaromaticum, Pseudomonas stutzeri, Pseudoalteromonas sp., and Vibrio sp. species were found predominantly in the rearingwater of Artemia franciscana

Effect of different feeds on reproduction performance, nutritional components and fatty acid composition of cladocer water flea (Daphnia magna)

This research evaluated the growth, survival, proximate and fatty acid composition of water flea (Daphnia magna) fed baker's yeast (BY) and three types of microalgae diets. In this study, two freshwater microalgae; Botrycoccus braunii (BB) and Chlorella vulgaris (CV), one marine spray-dried microalgae, Nannochloropsis oculata (SDN), and baker's yeast were evaluated for herbivorous zooplankton Daphnia magna. Survival, reproduction and population density of Daphnia magna have been studied. Daphnia reproduction was enhanced by utilization of baker's yeast diet with increasing egg number, juvenile and adult female numbers among treatments during the experimental period. Daphnia fed SDN diet increased egg number only 7th day of experiment. Population density and survival was positively affected by utilization of baker's yeast at the end of the experiment. Protein levels enhanced by SDN diets while Daphnia fed Botrycoccus braunii diet showed the highest lipid and EPA content in Daphnia. Overall, each diet improved different part of nutrients in Daphnia biomass

THE EVALUATION OF THE GROWTH PERFORMANCE OF A CYANOBACTERIAL ISOLATE PHORMIDIUM LUCIDUM (KÜTZİNG EX GOMONT 1892) GROWN UNDER DIFFERENT ENVIRONMENTAL CONDITIONS AND ITS USE AS A DIETARY SOURCE FOR DAPHNIA MAGNA (STRAUS 1820)

This study presents the effect of cyanobacterium isolated from BollukLake (Konya, Türkiye) which is a saline lake on the growth performance of Daphniamagna. Isolated cyanobacteria species were identified as Phormidium lucidumaccording to its 16S rDNA sequences. The effects of different growth conditionsincluding pH (7.18, 8.15, 9.17 and 10.26), light intensity (1200, 2400, 3600 and 4800lux), temperature (10, 20, 25 and 30°C) and nitrogen concentrations (0.25, 0.5, 1.0 and1.5 g/L) on P. lucidum was studied. Effects of each environmental factor onbiochemical composition (total protein, total lipid and chlorophyll-a concentration) ofP. lucidum were also studied. The optimum growth conditions were found as pH 7.18,ambient temperature 20°C, nitrogen 0.25 g/L and light intensity 3600 lux, after a 2-week incubation period. The effects of various mixtures of the cyanobacteria andChlorella vulgaris which is a common feed for Daphniids were also evaluated for theireffects on the growth rates of D. magna. The best growth rate for D. magna wasobtained in the medium containing 100% P. lucidum at the end of the 13ᵗ ͪ day

The influence of diet on the microbiota of live-feed rotifers (Brachionus plicatilis) used in commercial fish larviculture

Live-feed is indispensable to commercial fish larviculture. However, high bacterial loads in rotifers could pose a biosecurity risk. While this may be true, live-feed associated bacteria could also be beneficial to fish larvae through improved feed utilization or pathogen inhibition following host microbiota modification. The study objective was to elucidate the largely unexplored microbiota of rotifers propagated on five different diets through bacterial community profiling by 16S rRNA gene amplicon sequencing. Investigated rotifer samples had a median observed alpha-diversity of 338 +/- 87 bacterial species. Alpha- and Gamma-Proteobacteria dominated the rotifer microbiota followed by members of classes Flavobacteriia, Cytophagia, Mollicutes, Phycisphaerae and Bacteroidia. Different diets significantly altered the bacterial communities associated with rotifers according to PERMANOVA test results and beta dispersion calculations. A common core rotifer microbiome included 31 bacterial species present in relative abundances over 0.01%. We discuss the functional role of some microbiome members. Our data suggested the presence of several known fish pathogens in stock rotifers. However, we found no evidence for increased loads of these presumptive taxa in propagated live-feed rotifers during this field trial

Effects of dietary vitamin D3 levels on survival, mineralization, and skeletal development of gilthead seabream (Sparus aurata) larvae

Vitamin D is an essential fat soluble micronutrient that helps in growth, bone development, calcium homeostasis and other metabolic process. The study on effect of vitamin D3 in marine fish larvae were very scarce irrespective of species. The present study determines the impacts of dietary vitamin D3 on growth performance, calcium absorption, mineralization, and skeletal anomalies during the development of gilthead seabream (Sparus aurata) larvae was assessed until 47 days post hatching. Diets containing four levels of vitamin D3 (0, 25, 30, 384 μg kg−1 or 11.6, 1000, 1200, 15,360 IU kg−1) were formulated to determine the effect of vitamin D3 at deficient, excess, and optimum levels. The gilthead seabream larvae in the present study fed with this wide range of vitamin D3 presented a constant growth with all the diets but presented signs of toxicity in excess level, affecting the survival, calcium uptake, and bone biomarker mechanism in larvae, which resulted in increased skeletal anomalies and mortality. An increase of dietary vitamin D3 up to 384 μg kg−1 significantly raised the whole body vitamin D3 content, calcium, and phosphorus intake and increased the incidence of skeletal anomalies, particularly cranial anomalies. The appearance of skeletal anomalies in larvae fed 384 μg kg−1 vitamin D3 was in association with the upregulation of bmp2, alp, and oc gene expression. However, larvae fed 0, 25, 30 μg kg−1 vitamin D3 showed higher survival than the group fed 384 μg kg−1 vitamin D3. Meanwhile vitamin D3 deficient diet 0 μg kg−1 presented with lower mineralization rate and increase incidence of maxillary anomaly. Thus, the current study revealed the evidence of vitamin D3 deficiency as well as toxicity in gilthead seabream larvae during the developmental process and conclude that the recommended dietary vitamin D3 level for gilthead seabream larvae may range between 25 and 30 μg kg−1 which improves larval survival, calcium and phosphate level and vertebral mineralization with reduced incidence of skeletal anomalies in gilthead seabream larva