Seasonal growth of Laminaria solidungula in the Canadian High Arctic in relation to irradiance and dissolved nutrient concentrations

TLDR: Culture experiments showed that significant growth of L. solidungula occurs at both of these photon flux densities, and sporophytes showed no ability to utilise glucose heterotrophically in the dark.

Abstract: Seasonal growth of Laminaria solidungula was measured year-round in the Canadian High Arctic. Growth rate was most rapid in winter and early spring under thick ice cover. Seasonal growth rate was strongly correlated with the concentration of available inorganic-N and negatively correlated with light avaibility. During the ice-free period, when growth rate was lowest, there was a build-up of organic reserves which were subsequently reduced through the winter. The total light received at 8 m was 590 Em-2 yr-1. At the lower depth limit of kelp (20 m) the annual light received was calculated as 49 Em-2 yr-1. Culture experiments showed that significant growth of L. solidungula occurs at both of these photon flux densities. Sporophytes showed no ability to utilise glucose heterotrophically in the dark.