Содержание метаболитов и энергетическая ценность бурой водоросли Ascophyllum nodosum (L.) Le Jolis в условиях Баренцева моря

Abstract

The brown seaweed Ascophyllum nodosum (L.) Le Jolis is a valuable producer of bioactive compounds and an important component of the Barents Sea ecosystem. Studying algal biomass and determining its energy value is relevant for assessing the overall status of the species in the ecosystem and its resource potential. To better understand the changes occurring in A. nodosum during the commercial summer–autumn harvesting period, it is important to investigate the allocation of metabolites within the thallus and the contribution of different structures to total biomass. In this study, biochemical parameters (total proteins, lipids, carbohydrates, polyphenols, chlorophyll a and c, total carotenoids and fucoxanthin) were determined using standard methods. Both in situ and laboratory‑processed biomass were measured, and, based on these data, the energy content and the energy equivalent of biomass were calculated. For the collection of A. nodosum, two nearby Barents Sea bays differing in hydrological conditions were selected—Zavalishina Bay and Korabelnaya Bay—where A. nodosum forms dense intertidal stands. It was found that biomass peaked in June in both bays, with minimal differences between sites and a mean value of 25 kg/m²; however, the energy equivalent of biomass at this time differed: in samples from Zavalishina Bay this parameter was 1,4 times higher, while ash content was 1,4 times lower. Algae from Zavalishina Bay also showed higher contents of polyphenols and fucoxanthin. The distribution of bioactive compounds was examined among functionally differentiated thallus zones (FDTZ)—receptacles, apical tips and the remaining thallus (thallus without apical tips and receptacles)—as well as in relation to reproductive phase (fertile vs. sterile thalli) and abiotic habitat conditions (a set of factors including salinity, temperature and wave exposure). Patterns of metabolite distribution in A. nodosum from the Barents Sea were identified under the influence of three factors: thallus zone, reproductive phase and habitat. The thallus zone factor had a substantial effect on the allocation of fucoxanthin, proteins, lipids, carbohydrates, chlorophyll c, chlorophyll a and total carotenoids. Habitat had a significant effect on the contents of polyphenols, proteins and fucoxanthin, as well as on the levels of carbohydrates and lipids. The reproductive phase of the algae significantly influenced the contents of proteins, polyphenols, chlorophyll c and lipids.