MEPS 204:119-130 (2000)  -  doi:10.3354/meps204119

ABSTRACT: Many seagrass species can be found in different stages of meadow formation, from recently established patches to fully developed meadows. However, little is known about how the fate of seagrass production (i.e. herbivory, decomposition, export and carbon storage), and its ecological implications, vary across meadow development. Here we examine the fate of production of the seagrass Cymodocea nodosa (Ucria) Ascherson across increasing stages of meadow formation in a Spanish Mediterranean coastal lagoon, Alfacs Bay. Differences in time elapsed since seagrass establishment explained only a modest fraction of the variability in the fate of production, with most production routes ranging over 1 order of magnitude for any given time. However, on the whole, leaf consumption by herbivores increased by 5-fold, and decomposition and export of detrital leaves by almost 2-fold from young (i.e. 0 to 2 yr since seagrass establishment) to old (i.e. 5 to 7 yr since establishment) stages of meadow formation. Below-ground decomposition also increased by almost 1 order of magnitude from young to old stages. These results indicate that longer-established C. nodosa patches transfer greater fluxes of production to consumers, and should thus support greater levels of secondary production. Moreover, seagrass biomass and detritus increased by 3-fold from young to old stages, showing that longer-established patches may act as greater sinks of organic carbon. These results suggest that generalizations about the extent of carbon storage and secondary production maintained by seagrasses must consider the stage of meadow formation typically exhibited by the species concerned.

KEY WORDS: Cymodocea nodosa · Meadow formation · Herbivory · Decomposition · Export · Biomass storage