Cultivation of a morphologically distinct strain of the sugar kelp, Saccharina latissima forma angustissima, from coastal Maine, USA, with implications for ecosystem services

Consumer interest and demand for North Atlantic sourced sea vegetables drives opportunities for aquaculture development in the northeast USA. The unique morphology and desirable culinary traits of the wild narrow-bladed kelp, Saccharina latissima forma angustissima, were successfully translated into a cultivated crop on two geographically distinct open-water farms in Maine, USA. Environmental conditions, growth, and tissue analysis were quantified. Peak meristematic growth rates for blade length occurred from March through April at 2.85 (±0.34) cm day−1. The kelp was harvested from May through June with yields of up to 17 (±4.4) kg m−1 of line and plant density of 330 plants m−1 of line at the Bristol farm and yields of 13.3 (±6.2) kg wet weight m−1 line and a plant density of 400 plants m−1 of line at the Sorrento farm. Second season yields at Sorrento were on average 24.1 (±6.3) kg m−1 of line. Both farms grew significantly narrower blades of f. angustissima than of the sugar kelp, S. latissima. Common garden experiments with the two morphotypes identified trait stability for length and width, while blade ruffles and thickness varied with the environment. Calculations estimating the nutrient bioextraction capability of the cultivated f. angustissima kelp harvested in June reveal N removal of 88.7 kg ha−1 and C removal of 1666.7 kg ha−1 (combined farm site averages). Overall, this unique kelp form has the potential as a new aquaculture crop for the Gulf of Maine while providing several coastal ecosystem services.