Improving nursery systems and clonal gametophyte seeding in Nova Scotian sugar kelp aquaculture

Abstract

Kelp aquaculture has the potential to enhance sustainable marine food production and ameliorate local climate change impacts, yet variability in nursery protocols continues to limit cost-effective scaling. This thesis investigated methods to improve sugar kelp (Saccharina latissima) growth and survivorship from the nursery phase through ocean cultivation. The effects of water motion and sporing density were examined in the nursery phase, finding that flow-through systems enhanced nutrient delivery and survivorship, while lower sporing densities produced longer sporophytes. I also tested the efficacy of clonal gametophyte-based seeding. While a six-week nursery phase produced viable outplants, 1–3-week treatments failed, underscoring the need for longer, more stable conditioning before ocean exposure. During outplanting, sporophyte density influenced morphology, revealing a manipulable trade-off between density and individual size. Collectively, these findings advance the development of reliable, efficient kelp nursery practices to build regional aquaculture and support kelp restoration efforts in a warming world.