Effects of pruning a temperate mangrove forest on the associated assemblages of macroinvertebrates

Mangrove forests around the world are being impacted by development in adjacent land and water areas. An after-control-impact study was undertaken to assess the effects of mangrove forest pruning on the associated benthic macroinvertebrate fauna. Pruning, undertaken 5 years before our sampling period, reduced the height of the forest canopy from 5 m to 1 m. Macrobenthic assemblages were sampled in September 2000 and January 2001 from two randomly selected sites within the pruned section of forest, and two sites in each of two control locations in the same forest. Assemblage composition in the pruned and undisturbed mangrove forests was not significantly different, nor were there significant differences in variability between the two areas. Similarity matrices for assemblages based on higher taxonomic groups and molluscs were highly correlated with similarity matrices for all taxa, indicating the utility of more rapid forms of assessment in this habitat. The results suggest that although short-term impacts may have occurred, no impact on macroinvertebrate assemblages was evident 5 years after the pruning.