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Proceedings of the Symposium on Mangrove Responses to Relative Sea-level Rise and Other Climate Change Effects, 13 July 2006 Catchments to Coast. The Society of Wetland Scientists 27th International Conference, 9-14 July 2006
Climate Change Resilience, Biodiversity Conservation
Available Online

Gilman, Eric.

2006
Mangrove systems occur extensively on low gradient tropical shorelines, where sedimentation enables resilience during sea-level rise (SLR). Within mangroves, inundation frequencies across the intertidal slope cause zonation of different species with elevation. This tight sea-level control of the seaward margin and zones within mangroves has been demonstrated by precise EDM survey. Hence species zones in mangroves are definitive indicators of sea-level position, and pollen distributions record the locations of different zones in the sedimentary record. Pollen stratigraphic records can be used to reconstruct Holocene sea-levels and show mangrove response to change. Mangrove response to sea-level rise has been investigated in Bermuda, the Cayman Islands, Tonga and southern New Guinea. Radiocarbon dating of stratigraphy determined a sediment accretion rate of 1 mm a1for the low island locations, and up to 1.5 mm a"1 in two estuaries of southern New Guinea. The IPCC SLR projections of 9-88 cm by 2100 equate to a rate of 0.9-8.8 mm a"1. Mangrove recession events and replacement by lagoon environments are shown to occur during more rapid sea-level rise. In Bermuda rates of SLR exceed 2 mm a1and the largest mangrove area having existed for the last 2000 years lost 26% area in retreat of its seaward edge during the last century. In Tonga, a large mangrove swamp persisted 7000-5500 yr BP during SLR of 1.2 mm a1, then retreated when the rate increased. In Cayman 20 km of mangroves died back between 4080 and 3230 yr BP, during SLR of 2.8-3.3 mm a1, to become a lagoon. In extensive swamps of southern New Guinea gradual Late Holocene retreat of mangrove zones occurred with SLR of 0.67 mm a1. Hence while low island mangroves are likely to be the most sensitive to projected SLR, continental margin mangroves will also suffer disruption and retreat.
Initial recolonization of Funafuti atoll coral reefs devasted by hurricane "Bebe"
Biodiversity Conservation
Available Online

Mergner Hans

1985
On the 21st of October, 1972, hurricane "Bebe" devas- tated a large part of Funafuti atoll, Ellice Islands. Among the most spectacular geomorphological alterations caused by the hurricane was a storm beach 19 km long, 4 m high and 37 m wide. The amount of coral debris washed up from the offshore coral reefs onto the reef flat was estimated at 2.8 x 10 tons of material (Baines, Beveridge and Maragos, 1974). The oceanside reef communities of the SE and E rim of the atoll had been totally destroyed, and those of the inner reefs of the lagoon side had been heavily damaged. Eight months after the storm a quantitative analysis of the resettlement and recruitment of coral species on 7 reef sections was carried out: the destruction of the biophysiographic zones could be described as increasing from the northern border and also to the W rim of the atoll. Near the centre at Fongafale the lagoon reef flat was covered by thick carpets of the brown alga Dictyota bartaysii, possibly brought about by eutrophication effects. The resettlement of the reef flat by corals began with the recolonization of branching corals as well as regeneration of the very few surviving massive corals: about 80% of the number of new colonies belong to Acropora (mainly A. humilis and A. hyaclnthus), and about 20% to Pocillopora eydouxi, Porltes lutea (?) and some Faviidae. The percentage of the area settled by the massive coral species is, however, greater than that settled by the branching species. Nevertheless, in the long-term, branching corals are expected to have a decisive influence on the future structural and biophysiographic zonation of the reef edge and reef flat, due to their more numerous young colonies, which are evenly scattered over the reef area, and due to their rapid growth rate. Consequently, an Acropora humilis - hyacinthus-community or an Acropora - Pocillopora eydouxi-assemblage can be predicted as the future biophysiographic zone.