Pollinators necessary for the reproductive success of critically endangered mangrove, Sonneratia griffithii

Abstract

• The mangrove, Sonneratia griffithii, is critically endangered. • S. griffithii has inbreeding depression observed thru low reproductive output. • S. griffithii is dependent on pollinators for reproductive success. • Macroglossus minimus and Eonycteris spelaea bats visit S. griffithii flowers. • Mangrove and cave protection with corridors for pollinators is recommended. Mangrove forests provide numerous ecosystem services, yet are disappearing rapidly. One such mangrove species negatively affected by deforestation and land conversion is Sonneratia griffithii , a critically endangered but under-studied species. To understand its reproductive biology, we conducted a pollination experiment and observed flower visitors that potentially pollinate this mangrove species. All experimental treatments (open pollination, insect pollination, hand-cross pollination, hand-self pollination, and spontaneous autogamy) produced fruit set to varying degrees. Results suggest that S. griffithii is suffering from inbreeding depression, as trees set few fruits even in the hand-cross (25 %) and hand-self (18 %) pollination treatments. Results also suggest that the species is dependent on pollinators, since the open (22 %) and insect pollination (18 %) treatments set 3 times as many fruits as the spontaneous autogamy treatment (6 %). Two bat species were mist-netted near S. griffithii flowers: Macroglossus minimus and Eonycteris spelaea . To protect this mangrove species, we recommend encouraging cross pollination by bats through local area and pollinator protection, as well as creating corridors between mangrove forest patches.