Recovery of experimentally created gaps within a tropical Zostera capricorni (Aschers.) seagrass meadow, Queensland Australia

The recovery of experimentally cleared plots in a meadow dominated by Zoste ra capricorni was monitored monthly by measurements of leaf shoot density a nd estimates of above-ground biomass from September 1995 to September 1996. The rate of recovery, relative importance of sexual and asexual reproducti on and the role of the seed bank on recovery were examined by manipulating the supply of sexual and asexual propagules. Cleared plots were mostly reco lonised by Zostera capricorni. Recolonisation occurred principally by asexu al growth from surrounding rhizomes. There was no significant recovery by s exual means, although flowering and fruiting were observed during the study period from July through to December with the highest density of sexual sh oots in early spring (109.7+/-24.4 shoots m(-2)). Seeds stored in sediments played no role in recovery. Above-ground biomass and shoot density in clea red plots where asexual regrowth was allowed recovered to the level of the uncleared controls after 12 months. Control (uncleared) plots showed distin ct seasonality in above-ground biomass, peaking in spring (71.2+/-3.4 g DW m(-2)), but not in shoot density, indicating that shoots became smaller rat her than less numerous in winter. The rate of asexual recovery slowed in au tumn corresponding to the period of biomass decline,in the control plots bu t rapidly increased in late winter and spring. (C) 1999 Elsevier Science B. V. All rights reserved.