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Biofouling constitutes one of the main obstacles in the sector of shellfish farming. Under this perspective, it is of highly importance to critically combine the updated information regarding the invasive potential of ascidian species, together with the factors contributing toward these events. The biological features of each species in relation to the gathering of the main non-indigenous species in the Mediterranean basin represent the first step toward mitigation of negative effects of the phenomenon. Further, there are limited studies investigating the physiological changes of bivalves caused by biofouling while leading to an increase in stress biomarkers. In the present review, the major ascidian species negatively affecting bivalve culture in the Mediterranean Sea are presented, alongside monitoring of ascidians from four Greek mussel farming locations as typical mussel culture cases. Among the main ascidian species, Styela plicata, Clavelina oblonga, Ciona robusta, Aplidium sp., Didemnum sp., Botryllus schlosseri, and Didemnum drachi are included, with the last three being the most harmful for this aquaculture sector. Based on the existing literature and research conducted so far, future research directions are proposed, in an effort to effectively control or efficiently manage ascidian biofouling organisms. Overall, perspectives toward the way we manage the biofouling phenomenon, such as the use of ascidian’s by-products in feedstuffs, chemical and pharmaceutical industry, or their incorporation in bivalve co-culture and integrated multi-trophic aquaculture systems represent promising alternative approaches.

Marine bivalves are exposed to several environmental stressors depending on fluctuations in abiotic factors (pollutants, salinity, and temperature) and biotic factors, including ascidian biofouling. Increased seawater temperature may lead to oxidative stress in marine animals, whereas the additional burden presented by ascidian biofouling narrows their thermal window and can cause a sharper decline in shellfish health, with subsequent effects on shellfish aquaculture. The aim of the present study was to investigate the role of seawater temperature variations in the severity of the stress caused by ascidian biofouling to Mytilus galloprovincialis cell machinery, particularly in the antioxidant defense system, and the apoptotic and autophagic pathways. Fouled and nonfouled mussels were seasonally collected, and several key indicators of the previously mentioned cellular processes were determined in their mantle and posterior adductor muscle tissues. Results indicate that ascidian biofouling increases hypoxic conditions and oxidative stress, subsequently triggering cell death pathways in mussels. Although the stress caused by ascidians may be the consequence of both reduced feeding and oxygen consumption, it affects the mussels to a greater extent than seasonality. The induced stress by biofouling, along with elevated water temperatures in summer, may severely harm mussel physiology and fitness, adversely affecting aquaculture sustainability. KEY WORDS: aquaculture. ascidians. biofouling. gene expression, climate change, stress response, INTRODUCTION Bivalve farming is considered one of the most sustainable seafood resources (Froehlich et al. 2018). Furthermore, the fact that 94% of mussel production, equivalent to a total yield of [...]

Purpose: The aim of the present study was to identify the contribution of nutrition, physical activity (PA), and total energy intake and expenditure on body weight and composition in adolescents. Methods: Body composition, PA, and dietary intakes from 904 Greek adolescents (446 boys and 458 girls; Age: 14.6 ± 1.5 yrs), were evaluated. All participants were assigned into three groups according to their age-sex adjusted Fat Mass Index: (A) Normal weight (N; N = 503), (B) Overweight (OW; N = 253), and (C) Obese (O; N = 148). Results: Significant differences were found for body weight and composition, basal metabolic rate (BMR) expressed per kg of body mass (normal weight children exhibited the highest values), physical-total energy expenditure, and energy balances between the groups ([eta] [superscript 2]: 0.138 to 0.657; p < 0.05). In contrast, no differences were found for macronutrients' and total energy intakes, food consumption and quality ([eta] [superscript 2]: 0.002 to 0.099; p > 0.05) between the three examined groups. Strong, negative correlations were observed between body weight, body fat percentage, PA, and total energy expenditure (r: -0.311 to -0.810; p < 0.001). Lower, negative correlations were found between body weight, body fat percentage, and macronutrients' daily intakes (r:-0.235 to -0.432; p < 0.05). BMR and total energy expenditure had strong, negative relative strengths for the determination of body weight and fat percentage. Conclusions: In conclusion, it seems that BMR, PA, and total daily energy expenditure expressed per body weight and not the nutritional and total energy intakes, were the primary determinant parameters of body composition and weight in adolescents.

Simple Summary: Research efforts over the past decade have uncovered new insights into functions of erythropoietin that point to new roles beyond erythropoiesis. Recent studies have demonstrated that erythropoietin is implicated in tissue protection, regeneration, and reproduction. In this context, the present study reveals for the first time that erythropoietin inhibits cell death by apoptosis and enhances the fertilizing capacity of bovine spermatozoa. Erythropoietin (EPO), a hormone secreted mainly by the kidney, exerts its biological function by binding to its cell-surface receptor (EpoR). The presence of EPO and EpoR in the male and female reproductive system has been verified. Therefore, some of the key properties of EPO, such as its antioxidant and antiapoptotic effects, could improve the fertilizing capacity of spermatozoa. In the present study, the effect of two different concentrations of EPO (10 mIU/μL and 100 mIU/μL) on bovine sperm-quality parameters was evaluated during a post-thawing 4-h incubation at 37 °C. EPO had a positive effect on sperm motility, viability, and total antioxidant capacity. Moreover, EPO inhibited apoptosis, as it reduced both BCL2-associated X apoptosis regulator (Bax)/B-cell lymphoma 2 (Bcl-2) ratio and cleaved cysteine-aspartic proteases (caspases) substrate levels in a dose-dependent manner. In addition, EPO induced sperm capacitation and acrosome reaction in spermatozoa incubated in capacitation conditioned medeia. These results establish a foundation for the physiological role of EPO in reproductive processes and hopefully will provide an incentive for further research in order to fully decipher the role of EPO in sperm physiology and reproduction. [ABSTRACT FROM AUTHOR]

In the context of evaluating the impact of environmentally friendly and sustainably produced alternative protein sources in fish feed, the present study's aim was to examine the overall physiological stress response in one of the main fish species of European freshwater aquaculture, Oncorhynchus mykiss (rainbow trout), following the partial substitution of fish meal (FM) with a Tenebrio molitor (TM) (yellow mealworm) full‐fat meal. In total, 222 rainbow trout individuals (115.2 ± 14.2 g) were allocated randomly into six tanks, three per dietary treatment, and were fed a formulated diet containing 60% yellow mealworm (TM60) compared to a control diet without insect meal (TM0). Both diets contained equal amounts of crude protein, dry matter and, lipid content, while the FM in TM60 was 100 g kg−1 corresponding to the one seventh of the TM0. Heat shock response (HSR), MAPK signalling, cell death pathways (apoptosis and autophagy), antioxidant defence mechanisms, and intermediate metabolism were evaluated. In general, HSR and MAPK signalling were activated in response to the inclusion of T. molitor. Moreover, triggering of apoptotic and autophagic processes and the onset of antioxidant defence mechanisms underlined the existence of physiological stress. Despite the apparent dietary‐induced stress, rainbow trout in the present study exhibited no mortality and no significant effects regarding growth performance parameters. Specifically, TM60 dietary inclusion resulted in no changes in final body weight, weight gain, and specific growth rate. However, feed intake depicted a statistically significant decrease in TM60 fish compared to TM0 individuals. Nevertheless, nutrient stress should be considered a limiting factor regarding the utilization of T. molitor in O. mykiss diet due to the associated risks for health and welfare. [ABSTRACT FROM AUTHOR]

The hatchery culture of bivalve mollusks depends on feeding with fresh microalgae which represent up to 50% of the production costs. We investigated the growth performance of juvenile Ostrea edulis and Ruditapes decussatus under 15% and 30% replacement of microalgae with Saccharomyces cerevisiae. Metabolic indices were measured along with weight-specific growth rate and condition index for 28 days. 15% substitution led to great results, whereas 30% yeast-fed treatments displayed poor growth and a depressed metabolism. [ABSTRACT FROM AUTHOR]

Simple Summary: Nutrition is one of the most important physiological processes for the growth and welfare of farmed animals, while interactions between the intestinal microflora and the host systems provide a key mechanism for enhancing and maintaining homeostasis. Probiotics exert a positive impact on organisms' growth and immune response, so the administration of rations enriched with probiotics is recommended. Although the physiological role of probiotics on vertebrates' growth and stress responses has been extensively studied in vertebrates, little is known regarding their effects on economically important invertebrates such as land snails. The aim of the present study was to investigate the effects of probiotic-enriched rations on the physiological responses in several tissues of the economically important farmed terrestrial snail, Cornu aspersum. Despite the absence of a direct effect on growth rate, an intense physiological response by various biomarkers was observed in all examined tissues. A large variety of microorganisms ingested with food constitute animals' intestinal microflora, enhancing and maintaining the homeostasis of the host. Rations enriched with probiotics are a method recommended to prevent undesirable conditions. To date, research has been limited to farmed animals and reared fish, creating a knowledge gap concerning the effect of probiotics on the growth rate, physiological responses, and energy metabolism of invertebrates such as the land snail Cornu aspersum. Herein, juvenile snails (26.23 ± 0.5 mm shell diameter and 8.23 ± 1.02 g body weight) were fed L. plantarum probiotic-enriched rations in two different proportions (1.25 mg and 2.5 mg), and their growth rate was monitored for three months. Additionally, the RNA/DNA and Bax/Bcl-2 ratios, HSP gene expression and protein levels, and ND2 expression, were measured in the hepatopancreas, digestive tract, and mantle. Although the snails' growth rate was not affected, the RNA/DNA ratio presented an increase in various tissues, indicating an intense physiological response. Also, probiotic administration demonstrated low levels of the Bax/Bcl-2 ratio. HSP levels were higher in the presence of probiotics, probably signaling an attempt by the animal to face potentially stressful situations. Finally, ND2 expression levels in the hepatopancreas indicate intense metabolic and antioxidant activity. [ABSTRACT FROM AUTHOR]

Mediterranean finfish aquaculture is mainly represented by the production of the gilthead sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) growing in marine cage farms. Despite the numerous benefits of fish farming, the ecological risk potentially caused by fish escapes to the wild populations is occasionally high. In the current study, an integrated review of fish escapes is presented regarding S. aurata and D. labrax escapes and their potential effect on the genetic composition of wild populations. The collected data from the literature are combined and discussed along with recorded escapes in a fish farm located in the Aegean Sea, Greece. According to these records, fish escapes present a generally stable rate, ranging between 0 and 2% in each escape event, which occur 5–8 times per year. Although for other farmed fish species worldwide, the ecological risk may be higher, this risk is probably lower in Mediterranean finfish populations, which are characterized by generally low levels of genetic differentiation. Nevertheless, the risk of genetic introgression still exists. Particularly in sea bream and sea bass farming, genetic structure and differentiation in wild populations seem to be unaffected for now. Nevertheless, suitable management measurements would be a useful strategy to avoid future negative effects of fish escapes. These strategies should be focused on further efforts towards recapture program development, reduced escapees' survival, and proper legislation. Furthermore, more data on escapees' survival percentage, their migration pathways, and the way these pathways relate to mortality, the type of escape event, and the season of release would be also valuable. [ABSTRACT FROM AUTHOR]