Proximate Constituents in the Sea‐grasses Zostera marina and Z. noltii in Ireland: Seasonal Changes and the Effect of Blade Removal

Abstract

Abstract. Zostera marina L. from the lower intertidal of Galway Bay and Dingle Harbour, Ireland, showed new blade growth in the winter and spring months, a period of high protein levels (to 22%). Soluble carbohydrates (28–49%) were highest in the rhizome in November and after blade production in May. During the period of blade production or blade removal by means of cropping, soluble carbohydrate levels decreased in the rhizome indicating a storage function. The diminutive upper intertidal species, Z. noltii (Hornem.) Reichb. from Dungarvan Harbour, Ireland, also had highest protein levels in its blades in November and May, but the level of soluble carbohydrates in its rhizome was low compared with the larger species. The study indicates that Z. marina, being a perennial with a rhizome that functions as a storage organ, shows “K” type ecological strategies compared with the smaller species.SummaryProtein as well as soluble and insoluble carbohydrate and lipid levels of the blades, rhizomes, and roots of Zostera marina collected seasonally from Galway Bay and Dingle Harbour, Ireland, were similar to published data for the species and to data of other seagrasses. Protein levels were high in the blades and highest during spring blade growth. Soluble carbohydrate was highest in the rhizome segments during the winter, decreasing during spring blade production or when the blades were cropped. In contrast, the diminutive species Z. noltii did not show a seasonal rise in soluble carbohydrate and its blades tended to have high levels of protein in both fall and spring collections. The storage of soluble carbohydrate and long‐term survival of Z. marina suggests that this species is more a “K” strategist, while Z. noltii appears to be an opportunistic species.