Title: Optimising hatchery conditions for Palmaria palmata: experimental knowledge transfer study to advance seeding techniques in Tanzania

Abstract

Jamila Kalmabo's final project will be published in due time. Until then we share the abstract and a link to a poster.

Hatchery-based seaweed seeding offers a promising method for producing high-quality, disease-free seedlings and enhancing sustainability in aquaculture. However, a limited understanding of optimal environmental conditions hinders broader adoption. This study investigated seeding optimisation for Palmaria palmata in an Icelandic hatchery, with the goal of transferring knowledge to improve seeding techniques in Tanzania. Fertile tetraspores were collected from Vatnsleysuvík, Iceland, and stored at 4°C and 7°C. Clean, fertile tissue samples (1x1 cm) were placed in triplicate Petri dishes with UV-filtered seawater and incubated at 4°C under a 12:12 h light/dark cycle. After spore release, the tissue was removed, and the dishes were filled with nutrient-enriched seawater and GeO₂, and germling development was monitored weekly. Sori were incubated for 0–3, 3–6, and 6–9 days to examine the effect of incubation duration, and spores were counted microscopically. The effects of water agitation (0 vs. 3 L min⁻¹), temperature (4°C vs. 7°C), and exposure duration (1, 3, and 5 hrs) on spore yield in 50 mL seawater samples were tested. Results showed that spore release began at day 7 for sori stored at 7°C (5,000–10,000 spores gFW⁻¹) and at day 3 for those stored at 4°C (33,000 spores gFW⁻¹). Spore yield increased with longer incubation: 1,302 spores gFW⁻¹ (0–3 days), 2,627 spores gFW⁻¹ (3–6 days), and 33,019 spores gFW⁻¹ (6–9 days). While agitation slightly enhanced spore release at 4°C, calm conditions significantly improved yields at 7°C. These findings highlight the importance of incubation timing, temperature, and water movement for hatchery success. This study provides valuable insights for cold-water species and offers transferable knowledge to support seaweed hatchery development in tropical regions such as Tanzania.