Forecasting land-cover change effects on waterbirds in Xiamen Bay, China: Determining prospective species winners and losers.

Waterbirds are vital to coastal wetland ecosystem, and play significant roles in global biodiversity maintenance, cultural and educational services, etc. Waterbirds are particularly vulnerable to environmental change, particularly land-cover change, which has severely degraded their ecological niches. Accordingly, this study developed a waterbird-habitat preference index to quantify waterbird dependence on Xiamen Bay's habitats and a subsidiary waterbird-specific habitat suitability index to predict potential effects of future land-cover change on waterbirds. Results showed that the waterbird-habitat preference index ranged from -9.8 to 18.71, indicating that habitat selection varied greatly among different waterbird species, where tidal flats were the most popular waterbird habitat. Additionally, most waterbird species showed a preference for more than one habitat, which could be indicative of their diverse ecological demands. Effects on waterbirds varied greatly among the three different land-cover scenarios, where positive benefits were predicted under the ecological protection scenario (EPS), while the greatest negative effects were observed under the development and utilization scenario (DUS). Effects also varied among different waterbirds species. Those under the current trend scenario (CTS) (e.g., Tringa brevipes and Calidris ruficollis) could be at risk for species abundance loss (i.e., losers) while others (i.e., Egretta garzetta and Saundersilarus saundersi) could benefit from increased abundance (i.e., winners). Generally, migratory and traveling birds were much more vulnerable than resident birds. Spatially, conservation priority should be given to the Dadeng Waters and those waters adjacent to it (i.e., Tongan Bay and Anhai Bay) because of the highest waterbird loss risk in these areas under a conflict between an urgent need to protect waterbird biodiversity and intense present and future land-cover development. The intent of this study is to provide a useful tool to explore land-cover effects on waterbirds in similar coastal regions, which can provide important information on protection and restoration strategies.

Checklist of the coral fish fauna of Xisha Islands, China.

BACKGROUND: The Xisha Islands are composed of the Yongle Islands and the Xuande Islands in Hainan Province, China. It has one of the highest species diversity in the world and is also a typical oceanic distribution area of coral reefs globally. The ichthyofauna of the Xisha Islands were recorded by underwater visual census in May 2019 and July 2020. The survey data were combined with previous records of species into the checklist of the Xisha Islands presented herein. A total of 691 species, belonging to 24 orders and 97 families, was recorded. The major families were Labridae, Pomacentridae, Serranidae, Chaetodontidae, Hexanchidae, Lutjanidae, Scaridae, Gobiidae, Scorpaenidae and Carangidae. In this study, the Coral Fish iversity Index (CFDI) of six families (Chaetodontidae, Pomacanthidae, Pomacentridae, Labridae, Scaridae and Acanthuridae) was 229, indicating 756 coral fishes. In terms of the IUCN Red List, one species is Critically Endangered (Glyphis gangeticus), six species are Endangered (Stegostoma fasciatum, Aetomylaeus maculatus, Aetomylaeus vespertilio, Epinephelus akaara, Cheilinusundulatus sp. and Xiphias gladius), 16 species are Vulnerable, and 13 species are Near Threatened in the Xisha Archipelago, so conservation should be strengthened in this area in the future. NEW INFORMATION: One species is a new record for China (Dischistodus pseudochrysopoecilus) and 23 species are newly found in the Xisha Islands.

Higher soil organic carbon sequestration potential at a rehabilitated mangrove comprised of Aegiceras corniculatum compared to Kandelia obovata.

The present study compared the ecosystem organic carbon (OC) stocks and soil OC sources between two 12-year-old monospecific mangrove sites comprised of different species (Kandelia obovata in tree form and Aegiceras corniculatum in shrub form). We tested whether the carbon sequestration performance following rehabilitation varied with plantation of species in different forms and whether mangrove vegetation sequestrate OC more rapidly than soil pool. The results showed that mangrove rehabilitation increased the ecosystem OC stock relative to that of a non-vegetated bare flat. The accumulation of soil carbon was accompanied by increased soil total nitrogen contents and decreased δ13C values of soil OC, indicating that the increases in OC and TN contents were a function of accumulation of 13C-depleted mangrove materials in the soil. The sequestrated OC over the 12 years was considerably less in soil than in biomass at each mangrove site, suggesting that mangrove vegetation contributes more rapidly than the soil to ecosystem OC sequestration following rehabilitation before the vegetation has reached maturity. Compilation of the carbon stocks from worldwide rehabilitated mangrove forests with various ages further supports this finding. The K. obovata site had an apparently higher biomass OC stock but less OC in the soil than those at the A. corniculatum site. There was a higher standing leaf litter stock on the forest floor and more mangrove materials incorporated into the top 15 cm soil at the A. corniculatum site. These results suggested that the two rehabilitated mangrove sites had different development trajectories of both biomass and soil OC sequestration. Moreover, the performance of ecosystem carbon sequestration was related to plantation of different mangrove species. These carbon sequestration feature of rehabilitated mangrove forests therefore deserve attention in future rehabilitation programs to promote carbon sequestration performance.