Contrasting recolonization strategies in multi-species seagrass meadows

Abstract

This study shows that in a multi-species seagrass meadow in a shallow and clear-water site, all the former seagrass species were able to recolonize in the artificially created gaps of 0.25 m2 in size within ca. 2 yr. Extrapolation of the recolonization curves of the different species predicted a full recovery within 10 yr post-disturbance. Fitted curves for the dominant species Enhalus acoroides and Thalassia hemprichii showed contrasting strategies, the latter having a comparatively high intrinsic rate, achieving full recovery within ca. 2 yr post-disturbance. E. acoroides was the latest species to establish and the projected full-recovery time was among the longest (ca. 10 yr). The effect of timing of gap creation was generally not significant (except for Syringodium isoetifolium) neither was the temporal variation in density of most species outside the gaps. As recolonization by sexual propagules was found to be low, increasing the gap size would most probably require a much longer recovery period. A crude estimate for E. acoroides would be >10 yr for 1 m2 of gap. Further, since the densities of most seagrass species vary significantly between sites, and colonization rates depend on adjacent seagrass densities, the recovery curves would also be different across sites.