Colonization and shift of mollusc assemblages as a restoration indicator in planted mangroves in the Philippines

We compared the mollusc assemblages of planted mono-specific Rhizophora mangroves of known different ages. As forest age increased, there was a shift in species composition, abundance and biomass of mollusc assemblages for all faunal types (infauna, epifauna and arboreal fauna). This shift was correlated with the changes in vegetation (increasing forest cover and above-ground biomass) and sediment characteristics (increasing organic matter and decreasing sand content). Some species dominate in young plantations (\u3c10 years old; Pirenella cingulata) and in intermediate plantations (10–15 years old; Nerita polita), while other species only occur in mature plantations and natural mangrove stands (\u3e15 years; Terebralia sulcata, Nerita planospira). The two former groups of species are mostly species of infaunal and epifaunal habitats, while the latter group is mainly composed of arboreal species. The shift in mollusc species composition and dominance may serve as a useful indicator of restoration patterns in planted mangroves

A review of mangrove rehabilitation in the Philippines: successes, failures and future prospects

SEAFDEC main author. CC covered journal. Open Access Journal. Full text available.From half a million hectares at the turn of the century, Philippine mangroves have declined to only 120,000 ha while fish/shrimp culture ponds have increased to 232,000 ha. Mangrove replanting programs have thus been popular, from community initiatives (1930s-1950s) to government-sponsored projects (1970s) to large-scale international development assistance programs (1980s to present). Planting costs escalated from less than US$100 to over$500/ha, with half of the latter amount allocated to administration, supervision and project management. Despite heavy funds for massive rehabilitation of mangrove forests over the last two decades, the long-term survival rates of mangroves are generally low at 10-20%. Poor survival can be mainly traced to two factors: inappropriate species and sites selection. The favored but unsuitable Rhizophora are planted in sandy substrates of exposed coastlines instead of the natural colonizers Avicennia and Sonneratia. More significantly, planting sites are generally in the lower intertidal to subtidal zones where mangroves do not thrive rather than the optimal middle to upper intertidal levels, for a simple reason. Such ideal sites have long been converted to brackishwater fishponds whereas the former are open access areas with no ownership problems. The issue of pond ownership may be complex and difficult, but such should not outweigh ecological requirements: mangroves should be planted where fishponds are, not on seagrass beds and tidal flats where they never existed. This paper reviews eight mangrove initiatives in the Philippines and evaluates the biophysical and institutional factors behind success or failure. The authors recommend specific protocols (among them pushing for a 4:1 mangrove to pond ratio recommended for a healthy ecosystem) and wider policy directions to make mangrove rehabilitation in the country more effective.We thank Raul Roldan, Team Leader of the FRMP-Project Management Consultants and Regional Adviser for Region 4A, for contributing FRMP data;Veneracion Garcia, Charles Castro and the staff of the Department of Finance-CBRMP Project Management Office, for helping the junior author gather CBRMP data; and to Ann Melano (formerly of the Coastal Marine Management Office) for information on DENR mangrove reforestation efforts. Our appreciation also goes to Stanley Tan of MIMA, Malaysia for the invitation to the International Conference and Exhibition on Mangroves of Indian and Western Pacific Oceans held in Kuala Lumpur August 21–24, 2006, where an early version of this paper was presented

Establishing mollusk colonization and assemblage patterns in planted mangrove stands of different ages in Lingayen Gulf, Philippines

We investigated the assemblage patterns and species composition of infaunal mollusks in different ages of planted mangroves (6-, 8-, 10-, 11- and 18-year old) in Lingayen Gulf, northwestern Philippines. The study aimed to determine if the mollusk assemblage was associated with the developing forest and if such patterns could provide evidence for restoration of habitat functionality. A total of 11 mollusk species were recorded. Only two species, Cerithidea cingulata (Gmelin, 1791) and Nerita polita (Linnaeus, 1758), consistently appeared in all stands where the former had increased biomass in maturing stands and the latter peaked in intermediate age stands. Vegetation structure and biomass, and sediment characteristics changed as plantations matured. Likewise, mollusk assemblages (based on species composition and biomass) significantly varied among different age stands. Such changes in assemblage patterns were correlated with vegetation and sediment characteristics. The groupings of mollusks species in the different stands can be categorized into: decreasing (species that have initially high biomass but disappeared in older stands); no detectable change (species that did not show any change in biomass); peaking (species that initially had low biomass, peaked at intermediate stands, and then diminished in mature stands; and, increasing (species that have increasing biomass with maturing stands). In summary, this study affirmed: (1) rehabilitated mangroves with increased forest structure and biomass can be effective in facilitating infaunal colonization; and (2) mollusk assemblage patterns changed as stands grow older

Mangroves: unusual forests at the seas edge

Mangroves form distinct sea-edge forested habitat of dense, undulating canopies in both wet and arid tropic regions of the world. These highly adapted, forest wetland ecosystems have many remarkable features, making them a constant source of wonder and inquiry. This chapter introduces mangrove forests, the factors that influence them, and some of their key benefits and functions. This knowledge is considered essential for those who propose to manage them sustainably. We describe key and currently recommended strategies in an accompanying article on mangrove forest management (Schmitt and Duke 2015)

Mangrove ecosystems under climate change

This chapter assesses the response of mangrove ecosystems to possible outcomes of climate change, with regard to the following categories: (i) distribution, diversity, and community composition, (ii) physiology of flora and fauna, (iii) water budget, (iv) productivity and remineralization, (v) carbon storage in biomass and sediments, and (vi) the filter function for elements beneficial or harmful to life. These categories are then used to identify the regions most vulnerable to climate change. The four most important factors determining the response of mangrove ecosystems to climate change are sea level rise, an increase in frequency and/or intensity of storms, increases in temperature, and aridity. While these changes may be beneficial for some mangrove forests at latitudinal distribution limits, they will threaten forest structure and functions and related ecosystem services in most cases. The interaction of climate change with human interventions is discussed, as well as the effects on ecosystem services including possible adaptation and management options. The chapter closes with an outlook on knowledge gaps and priority research needed to fill these gaps