PROPAGULE PREDATORS IN KENYAN MANGROVES AND THEIR POSSIBLE EFFECT ON REGENERATION

Grapsid crabs can play a considerable role in the predation of mangrov e propagules and possibly are a threat to the regeneration of mangrove s, whether natural or artificial. Experiments consisting of artificial plantation of mangrove juveniles were set up in Gazi Bay (Kenya), Gra psid crabs, particularly Neosarmatium meinerti in the most landward fr inge and N. smithii and Sesarma guttatum in the middle fringe of the m angrove forest, were found to be a regeneration-limiting factor. Almos t 100% (n = 40) of the landward plantations were cleared. There was a slight initial preference for Rhizophora propagules lying horizontally on the mangrove floor, which simulates the position of a stranding pr opagule. In Mida Creek (Kenya) the snail Terebralia palustris was obse rved predating mangrove propagules. This study shows that crabs may af fect the regeneration potential of mangroves, and snails might also be a factor in predation. A need to actively search for ways to protect reafforestation plots from predators of mangrove tree juveniles is nec essary.