Seasonal nitrogen speciation in temperate seagrass Posidonia oceanica (L.) Delile

Seed nutrient content and nutritional status of Posidonia oceanica seedlings in the northwestern Mediterranean Sea

“…Results presented here indicate that the distribution of nutrients within seedling tissues was comparable with the pattern reported for adult plants (Alcoverro et al 2000, Invers et al 2002, Lepoint et al 2002, with high values of P and N in rhizomes and minimum values in roots. The decrease in the nutrient tissue concentrations observed between May and December may indicate that in this period the nutrient demands for active leaf growth exceed uptake, and part of this demand was met by the reserves accumulated in excess of growth demands during the previous winter.…”

“…Nutrient limitation in mature stands may be high from May to October, and may involve both N and P (Alcoverro et al 1997). To compensate for seasonal nutrient limitation the plant has evolved a complex strategy of nutrient conservation and recycling (Alcoverro et al 1995, 1997, Invers et al 2002, Lepoint et al 2002. Flowering and fruit production is highly variable in space and in time, with intensive synchronized flowering episodes occurring at 8 to 10 yr intervals (Balestri & Cinelli 2003, Balestri 2004, Diaz-Almela et al 2006.…”

Differential element assimilation by sea urchins Paracentrotus lividus in seagrass beds: implications for trophic interactions

“…On the one hand (and as indicated by the C:N values), most of the total carbon content in seagrasses is in the form of cellulose and other structural components (Duarte 1990) that cannot be easily utilised by animals; on the other hand, the fraction of assimilable-nitrogen components is lower in old Posidonia oceanica leaves. On average, soluble nitrogen compounds in old leaves account for only 0.7% dry weight (Invers et al 2002); hence a very important fraction of the nitrogen in old leaves available to sea urchins comprises structural refractory nitrogen. Therefore, although N concentrations are similar in both food sources, the availability of this N differs, which could explain the observed 'preferential' assimilation of epiphytic nitrogen.…”

Nitrogen dynamics in Posidonia oceanica cuttings: implications for transplantation experiments

“…Like other seagrass species, P. oceanica has a complex nitrogen budget in order to meet its nitrogen requirement (Lepoint et al, 2002b). This budget involves leaf and root N uptake, N storage strategies and N recycling (Alcoverro et al, 2000;Invers et al, 2002;Lepoint et al, 2002a,b). Moreover, Marba et al (2002) show a strong physiological integration of P. oceanica ramets, with a transfer of nitrogen from parent shoot to new shoot.…”