Louise Kregting1,2, Emma Healy1,3 Molly Crowe1,2 and Mánus Cunningham1,2
1Queen’s Marine Laboratory, Queen’s University Belfast, 12-13 The Strand, Portaferry, BT22 1PF, Northern Ireland, UK.
2School of Natural and Built Environment, Queen’s University Belfast, Belfast, BT9 5BN, UK.
3School of Biological Sciences, Queen’s University Belfast, 19 Chlorine Gardens, Belfast, BT9 5DL, Northern Ireland, UK.
Water motion is a fundamental component of the ocean and important for the wellbeing of seaweeds in the environment as it influences factors such as nutrients and light availability. However, during cultivation in hatcheries, seaweeds are often grown with just air stones as a form of water movement. Essentially, too little motion may result in mass-transfer limitation, potentially slowing the growth rate of the seaweed in the hatchery phase. To ensure security of a reliable large-scale supply of seaweed; at a cost which is competitive with alternative food sources, time in the hatchery phase should ideally be optimised. The influence of oscillatory versus mesocosms with air stones on the growth and density of the microscopic stages of the sugar kelp Saccharina latissima, were investigated. A significantly higher sporophyte density was found when the seaweed was exposed to oscillatory motion in comparison to the mesocosms (F= 28.67, P < 0.001); however, when there was little external force acting on the blades, as in the mesocosm, a significant increase in blade length was observed (F = 42.26, P < 0.001). Providing water motion therefore did increase the density, but not growth rate. However, whether, traditional methods of cultivating seaweeds in the hatchery means there is a trade off in blade strength and therefore more susceptible to breakage when grown out in the field in more energetic environments is unknown and requires further investigation.