Development and Diversity of Epibiont Assemblages on Cultivated Sugar Kelp (Saccharina latissima) in Relation to Farming Schedules and Harvesting Techniques

Abstract

Seaweed farming in Europe is growing and may provide environmental benefits, including habitat provisioning, coastal protection, and bioremediation. Habitat provisioning by seaweed farms remains largely unquantified, with previous research focused primarily on the detrimental effects of epibionts, rather than their roles in ecological functioning and ecosystem service provision. We monitored the development and diversity of epibiont assemblages on cultivated sugar kelp (Saccharina latissima) at a farm in Cornwall, southwest UK, and compared the effects of different harvesting techniques on epibiont assemblage structure. Increases in epibiont abundance (PERMANOVA, F4,25 = 100.56, p < 0.001) and diversity (PERMANOVA, F4,25 = 27.25, p < 0.001) were found on cultivated kelps over and beyond the growing season, reaching an average abundance of >6000 individuals per kelp plant with a taxonomic richness of ~9 phyla per kelp by late summer (August). Assemblages were dominated by crustaceans (mainly amphipods), molluscs (principally bivalves) and bryozoans, which provide important ecological roles, despite reducing crop quality. Partial harvesting techniques maintained, or increased, epibiont abundance and diversity beyond the farming season; however, these kelp plants were significantly fouled and would not be commercially viable in most markets. This paper improves understanding of epibiont assemblage development at European kelp farms, which can inform sustainable, ecosystem-based approaches to aquaculture.

Home sweet home: Comparison of epibiont assemblages associated with cultivated and wild sugar kelp (Saccharina latissima), co-cultivated blue mussels (Mytilus edulis) and farm infrastructure

“…epibiont taxa present in this study were consistent with those previously recorded on kelp plants at the farm in Porthallow Bay(Corrigan et al 2023), as well as studies conducted elsewhere at comparable sites in Europe on both farmed (Bak, Mols-Mortensen, and Gregersen 2018; Bekkby et al 2023; Forbord et al 2020; Førde et al 2016; Peteiro and Freire 2013; Rolin et al 2017; Visch, Kononets, et al 2020; Visch, Nylund, et al In Norway, entire plants of both S. latissima andA. esculenta exhibited lower faunal richness and lower overall biodiversity than wild kelp plants after both three and seven months of cultivation(Bekkby et al 2023).…”

“…The differences in these ndings, and other recent understandings of how epibiont assemblages vary widely between cultivation sites, dependent on latitude and environmental factors such as temperature, ow regime and wave exposure (Boderskov et (Forbes et al 2022). For seaweed farming to provide valuable long-term habitat, innovations to maintain biodiversity beyond the harvest point are being trialled, including partial harvesting techniques (Corrigan et al 2023). Co-location with other marine industries, such as renewable energy, or longer-lived aquaculture species, such as bivalve shell sh, can also increase the longevity of habitat.…”

Integrating environmental and ecological monitoring with seaweed farming

“…Being a newly established farm, the expected diversity has not yet fully materialised. Over time, as the farm matures, a more diverse assemblage is anticipated, reflecting the patterns observed at more established sites [40].…”

The sugar kelp Saccharina latissima II: Recent Advances in farming and applications

“…Epibionts, and in particular encrusting bryozoan, grow as colonies that cover the frond surface and form a barrier inhibiting nutrient and light absorption (Andersen et al 2019) and often cause loss of biomass due to increased drag and friction and decreased flexibility (Krumhansl et al 2011). Other common epibionts on S. latissima are hydroids, crustaceans, bivalves, sponges, tunicates, snails, benthic diatoms, and filamentous algae (Krumhansl et al 2011;Forbord et al 2020a;Corrigan et al 2023) and bacterial colonies (Liu et al 2022;Burgunter-Delamare et al 2023). Biofouling makes seaweed biomass less appealing for human consumption and affects the commercial value of the yield.…”