Photosynthesis, Respiration and other Factors Influencing the Growth of Laminar/a ochroleuca PYL below 50 Metres in the Straits of Messina

. The population of Laminaria ochroleuca in the current swept Straits of Messina was investigated regarding its age structure and photosynthesis. Age structure appears to be determined by sporadic recruitment and the limitation of growth due to peak currents decapitating older plants, which is corroborated by drag force resistance calculations. The calculation of a carbon budget from measurements of photosynthesis and dark respiration both in the laboratory and in situ shows that L. ochroleuca cannot satisfy its carbon demands for growth and respiration at 50 m depth and no satisfactory explanation can be given for its rapid growth between 50 and 100 m.