Document: TOD-3-48-42

Effects of pre-dispersal predation by insects on recruitment of the grey mangrove Avicennia marina.

MINCHINTON, T.E.* ^1,2 and M.DALBY-BALL ¹

University of Wollongong, New South Wales, Australia. ¹
University of California at Santa Cruz, Santa Cruz, CA 95064, USA. ²

Abstract:
In temperate mangrove forests in Australia, fruit of the grey mangrove Avicennia marina undergo intense herbivory by larval insects before they fall from the trees and disperse. Surveys to quantify the incidence of pre-dispersal predation revealed that 53% of fruit had been damaged by larvae. We did two field experiments to test hypotheses that damage experienced by fruit while developing on the trees affects the subsequent establishment, survival, and growth of seedlings. The first experiment showed that the establishment of seedlings was not influenced by pre-dispersal predation. In contrast, the second experiment revealed that seedlings established from fruit that had undergone pre-dispersal predation were significantly shorter than those that had developed from undamaged fruit. It appears that the partial consumption of fruit before dispersal reduces the cotyledonary reserves available for the initial growth of seedlings. Importantly, pre-dispersal predation resulted in the elimination of the larger size classes of seedlings, and shorter seedlings exhibited reduced survival. These results demonstrate that pre-dispersal predation by insects is likely to play an important role in determining the patterns of recruitment of mangrove seedlings.

Keywords: insects, mangroves, pre-dispersal predation, recruitment

This abstract is being presented at: 2:15 PM in session:
Oral Session #18: Mangrove Ecology.