The green seaweed Ulva: tomorrow's "wheat of the sea" in foods, feeds, nutrition, and biomaterials.

Ulva, a genus of green macroalgae commonly known as sea lettuce, has long been recognized for its nutritional benefits for food and feed. As the demand for sustainable food and feed sources continues to grow, so does the interest in alternative, plant-based protein sources. With its abundance along coastal waters and high protein content, Ulva spp. have emerged as promising candidates. While the use of Ulva in food and feed has its challenges, the utilization of Ulva in other industries, including in biomaterials, biostimulants, and biorefineries, has been growing. This review aims to provide a comprehensive overview of the current status, challenges and opportunities associated with using Ulva in food, feed, and beyond. Drawing on the expertise of leading researchers and industry professionals, it explores the latest knowledge on Ulva's nutritional value, processing methods, and potential benefits for human nutrition, aquaculture feeds, terrestrial feeds, biomaterials, biostimulants and biorefineries. In addition, it examines the economic feasibility of incorporating Ulva into aquafeed. Through its comprehensive and insightful analysis, including a critical review of the challenges and future research needs, this review will be a valuable resource for anyone interested in sustainable aquaculture and Ulva's role in food, feed, biomaterials, biostimulants and beyond.

Using otolith and body shape to discriminate between stocks of European anchovy (Engraulidae: Engraulis encrasicolus) from the Aegean, Marmara and Black Seas.

European anchovy, a small pelagic fish, plays a significant role in the blue economy, with remarkable commercial, ecological and culinary values. In this study, the variability in the shapes of the body and sagitta otoliths was examined to identify the different anchovy stocks in the Black Sea (26.5°E-39.9°E, 38.7° N-42.1°N) and adjacent regions, i.e., the Sea of Marmara and the Aegean Sea. The body shape was assessed with geometric morphometrics, while shape indices and elliptic Fourier analysis were used to evaluate the shape of the sagitta otoliths. The data were analysed using multivariate and univariate analysis of variance, discriminant function and principal component analysis. The anchovy population could be divided into five distinct stocks based on body shape, with an overall leave-one-out cross-validated correct classification of 85.6%. The geometric morphometrics revealed significant differences in body depth, snout, lower jaw and caudal fin. The differences in sagitta otolith shape also revealed the existence of four distinct stocks with an overall leave-one-out cross-validated correct classification of 46.5%-69.3%. The elliptic Fourier analysis revealed two main stocks of anchovy from the Black Sea as the Eastern-Middle Black Sea stock and the Western Black Sea stock. Based on the elliptic Fourier analysis, the differences in the sagitta otoliths increase in magnitude with increasing geographic separation, first manifested at the otolith anterior notch, followed by changes in the otolith width. The findings affirmed the existence of distinct stocks that should have important implications for effective management of this pelagic fish in the Black Sea and adjacent regions.

Temperature, meal size and body size effects on the gastric evacuation of rainbow trout: modelling optimum and upper thermal limits.

This study examined the rate and course of gastric evacuation (GE) in rainbow trout Oncorhynchus mykiss in relation to meal size, body size and temperature. The GE experiments were performed on small (mean ± 95% C.I., 17.7 ± 0.5 cm total length), medium (22. 9 ± 0.2 cm) and large (28.3 ± 0.3 cm) rainbow trout fed meals of different sizes using commercial food pellets at water temperatures T ranging from 7.8°C to 19.2°C. Estimating the shape parameter of a general power function suggested that the square root function adequately described the GE in rainbow trout independently of meal size. The effects of total body length L and weight W on gastric evacuation rate (GER) were described by simple power functions. The square root function was further expanded by a temperature function with temperature optimum to describe the effect of temperature. The expanded square root function revealed a considerable effect of body size and temperature on the GER of rainbow trout. The GER increased exponentially with rising temperature, reached an optimum at c. 18.5°C and then declined abruptly to zero at c. 21°C. The GER of rainbow trout could thus be described by d S t d t = - 0.00152 L 0.75 e 0.08 T 1 - e 1.18 T - 20.9 S t (g h-1 ) or d S t d t = - 0.00440 W 0.26 e 0.08 T 1 - e 0.97 T - 21.1 S t (g h-1 ), where St is the current stomach content mass (g), and at post-prandial time t (h). These functions should prove useful to calculate total GE time as well as stomach fullness at different post-prandial times and therefore provide valuable information to develop optimal feeding strategies for farming of rainbow trout.

Sexual dimorphism in the otolith shape of shi drum, Umbrina cirrosa (L.), in the eastern Mediterranean Sea: Fish size-otolith size relationships.

Little is known about possible differences in sagitta otolith size and shape between sexes of the shi drum, Umbrina cirrosa, and relationships between their body and otolith size. Thus, this study aimed to fill this knowledge gap via examination of 414 sagittal otoliths from 108 male (total length 13.8-26.8 cm) and 99 female (13.5-26.7 cm) U. cirrosa caught between May 2017 and April 2018 in gillnets set at a depth of ~15 m in Mersin Bay, Eastern Mediterranean Sea. No statistical differences were observed between the shape indices of the left-sided and right-sided sagitta. However, there were significant differences in the size and shape of otoliths between males and females. The slopes of allometric power functions from otolith width × fish sizes gave significant differences between males and females (ANCOVA, P < 0.05). The relationship for length × weight of otoliths from both males and females showed isometric growth, whereas the relationship of otolith width × otolith weight showed positive allometry. Negative allometric growth was observed for the relationship otolith length × otolith width. In summary, this study revealed the presence of sexual dimorphism in the otolith shape of U. cirrosa, and the data on regression relationships of fish-otolith sizes can be used to estimate fish size from U. cirrosa otolith sizes.