Mangroves in Small Island Development States in the Pacific: An Overview of a Highly Important and Seriously Threatened Resource

Mangroves are critical resources in small island developing countries in the Pacific where they provide food, a range of products and ecological services that are used by coastal communities. In many of the countries that have mangroves, between 50–80 % of commercial and subsistence fish species used by people spend some part of their life cycle in the mangroves where the detritus and the existing life forms contribute to the productivity of the coastal water that is vital for the habitation of these islands. Mangroves also protect the shorelines and are harvested for timber and non-timber products such as charcoal, dye and medicine. Ironically, this important resource is increasingly cleared in large amounts to allow for infrastructure development, agriculture, fish farming, hotel sites, industrial areas and dumps. Most small island countries in the Pacific Islands do not have any effective management plans for their mangrove forests, which are now under serious threat because of their increasing alteration to accommodate other uses. In addition, the changes in climate and sea levels and their impacts and how these are being addressed and attended to at different levels in the Pacific Islands will be discussed to show the attempts at all levels to accommodate the changing conditions. Many of these countries still cannot determine the factors that influence the sustainability of their mangroves which normally come under the responsibility of ministries or departments of forestry, fisheries, natural resources, environment and lands. It is common to have jurisdictional overlaps and conflicting sectoral policies. This overview will present the current state of mangroves and some of the issues that characterise their use in the Pacific Islands, the threats they face and the management arrangements that are in place. The chapter will also illustrate the roles of the customary and traditional owners of the resource and governments at the local, national and regional levels and the challenges that mangrove management must overcome in order to ensure the integrity and health of this habitat that is fundamental to human wellbeing

Colour differentiation in a coral reef fish throughout ontogeny: habitat background and flexibility

Colour polymorphism is widespread in animals but, in contrast to other types of polymorphism, has been little explored during ontogeny. Among coral reef fish, the surge damselfish Chrysiptera leucopoma settles in the larval stage as a yellow morph, whereas 2 colour morphs (yellow and brown) are apparent in adults at Rangiroa Atoll, French Polynesia. To understand this dimorphism, we tested, under controlled conditions, the hypotheses that: (1) environmental cues (habitat background and conspecific density) play important roles in morph differentiation during ontogeny and (2) morph colouration is reversible. Our first experiment showed that a dark habitat background induced the formation of the brown morph, while C. leucopoma larvae kept their yellow morph when placed in aquaria with a bright habitat background. Colour change from yellow to brown also occurred within the bright habitat, but only at high conspecific densities. Our second experiment showed that colour change was reversible within 15 d post-settlement, but not at the adult stage. Overall, our results highlighted that the studied polymorphism may be environmentally induced and reversible during the first post-settlement days of this coral reef fish