Pollen Fertility Status in Coastal Plant Species of Rotuma Island

The Island of Rotuma is facing widespread destruction and degradation of its flora. This investigation was conducted to determine the pollen fertility status in thirty two species of economic and environmentally important coastal species, which are reproducing freely thus most suitable to rehabilitate coastal areas. Pollen fertility status in these species varied from as low as 38% in Canavalia cathertica to as high as 100% in Hernandia nymphaeifolia and Vigna marina. It was interesting to note that species within same genus showed wide range of pollen viability. However, most of the species investigated had high pollen viability especially in those species, which grow close to sea. It was recorded that pollen fertility was low in small fragmented populations. This showed the effect of population size on reproduction. Larger sized populations showed high percentage of pollen fertility. 1. Introduction Rotuma is a small isolated volcanic oceanic island located 465 km to the northwest of the Republic of Fiji. Because of its relative isolation from the rest of the Fiji Group and its geographical remoteness from all the other Pacific Islands (the closest being Niulakita Island in Tuvalu, which is approximately 350 km to the northeast), it has been largely neglected in the botanical studies and surveys of the Pacific Islands and Fiji. Rotuma also encounters widespread destruction and degradation of its flora. The clearing of forests for plantations and settlements has resulted in the loss of many species. For the better part of the 19th century, Dillon (1829) and Wood (1875) reported that the island was densely populated and that most of its interior was cleared for towns and settlements. Gardiner (1898) observed that the whole island, wherever practicable, was at one time tilled. There were signs of forest clearing even on the steepest slopes and food crops, such as bananas, were observed growing at the bottom of hills for a very long time (Gardiner 1998). At the arrival of European trading and whaling ships, the attraction of trade with foreigners lured the population away from the interior of the island to settle along the coast. Towards the end of 1800 (Gardiner 1898), the towns and settlements in the interior of the island were abandoned and the entire population was living along the coast (Russell 1942). The movement of population from interior to coastal areas resulted in the clearing of all coastal land suitable for agriculture and settlement and exposed the coastline to erosion during heavy rainfall and high tides. Most Rotuman coastal plant species are of very high cultural utility (Thaman, 1992). The coastal plant species are used for food, clothing, construction, carving, medicine and cultural attire, to mention a few. The frequent removal of these species together with the lack of understanding of consequences and advantages of replanting led to serious coastal degradation and to the