Co-cultivation with blue mussels increases yield and biomass quality of kelp

• Published in: Aquaculture 2022-03, Vol.550, p.737832, Article 737832
• Main Authors: Hargrave, Matthew S., Nylund, Göran M., Enge, Swantje, Pavia, Henrik
• Format: Article
• Language: English
• Subjects: Biofiltration; Biofouling; Biological Sciences; Biologiska vetenskaper; biomass; brown alga; cultivation; Epiphyte; finfish; food quality; IMTA; monoculture; mussel culture; Oceanografi, hydrologi, vattenresurser; Oceanography, Hydrology, Water Resources; Pigment; Saccharina latissima; Sweden; yield response
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2021.737832

Integrated multi-trophic aquaculture (IMTA) has to date largely centred on a fed species, often finfish or shrimps, alongside which extractive species, such as bivalves or seaweeds, have been placed. In comparison, IMTA systems excluding a fed component have received little research. Here we report a field study of an IMTA cultivation of the sugar kelp, Saccharina latissima, and the blue mussel, Mytilus edulis, on the Swedish west coast. Kelp were cultivated at two depths, 1-2 m and 3-4 m, either 10 m downstream of commercial scale blue mussel farms, or at control (monoculture) sites at least 500 m from the nearest farm. Significant enhancement of kelp yields in terms of both blade length and biomass was observed in IMTA treatments compared to monoculture, with a mean increase in length of 22% and biomass of 38%. Moreover, kelps co-cultivated with mussels displayed an epiphyte reduction of more than half compared to kelps grown in monoculture, with a 15% coverage in monoculture compared to 6% in co-culture. Significant increases in pigment content were also detected, with higher levels of chlorophyll a, fucoxanthin and phaeophytin in IMTA treatment kelps in comparison to monoculture. This study provides evidence for the potential of IMTA systems containing solely extractive species and presents factors beyond nutrient enrichment as drivers for enhanced growth in these systems. •IMTA with blue mussel farms increased yields of S. latissima.•Irradiance drove kelp growth rather than nutrient enrichment.•Mussel biofiltration resulted in drastically fewer epiphytes on kelp blades.