Dynamics of “Blue Carbon” in sub-tropical mangrove environments
“Blue carbon” refers to carbon sequestered, stored and consumed in marine habitats. With their strong ability to achieve high productivity despite the stressful environmental conditions, coastal wetlands such as saltmarshes and mangrove forests sequester large quantities of carbon from the atmosphere and turn these into biomass. The typically low-oxygen, saline condition of these habitats also retards decomposition of carbon accumulated in the sediment. Together with the complex structure offered by the plants to help trap organic matter carried by tides or river discharge, coastal wetlands are some of the most significant carbon storages among the world’s ecosystems.
Environmental sustainability of coastal megacities
This joint project under the auspices of the ENSURE (Environmental Sustainability and Resilience) collaborative scheme of CUHK and University of Exeter, UK, examines how changes in habitat quantity and quality may impact the long-term sustainability of rapidly urbanising coasts.
Trophodynamics of soft-sediment coastal habitats in Hong Kong
(Environment and Conservation Fund, Hong Kong)
Project website: https://www.ecfsoftshores.msl.sls.cuhk.edu.hk/
This project employs stable isotope analysis to elucidate the structure and function of food webs in local soft-sediment habitats and assess the trophic connectivity that underpins cross-habitat ecological sustainability. Information obtained from the field can be used to evaluate the site's capacity for the provision of ecosystem goods and services (e.g. fishery production), as well as their resilience towards future natural and anthropogenic disturbances.
Value of small mangrove patches in the Pearl River estuary to commercial fisheries
(Marine Ecology Enhancement Fund, Hong Kong)
Mangrove forests have long been hypothesized to play an important role in sustaining fisheries in tropical estuaries by supporting the larval and juvenile stages of fish. Once lined with luxuriant mangrove forests, the coastline of the Pearl River estuary (PRE) is now highly modified and strongly disturbed, with only relatively small patches of mangrove forests remaining to support the many potential ecosystem services of these productive ecosystems. This project uses 3D sensing technology and individual-based modelling (IBM) approaches to evaluate the importance of small-scale peri-urban mangrove forests in the PRE to juveniles of fish species of commercial and ecological importance.
Global Wetlands Project (GLOW)
The GLOW project coordinated by Griffith University, Australia, is a worldwide collaboration effort to inform and empower coastal conservation. The focus is on generating predictive models for the mangrove, seagrass, and saltmarsh habitats, and deriving a global coastal wetland health index to guide conservation actions.
Is there a functional microphytobenthos in tropical mangrove ecosystems?
(Research Grants Council General Research Fund 2021-23, Hong Kong)
The microphytobenthos (MPB) has traditionally been regarded as a negligible component of tropical mangrove ecosystems because of light limitation under the tree canopy. A few methodological challenges also contributed to the general lack of knowledge on the mangrove MPB community and its trophic role. MPB are difficult to characterise in mangroves due to their small size and the considerable methodological challenge in separating microalgae cells from the fine detritus-laden sediment. Contamination by mangrove detritus reduces the resolving power of stable isotope analysis, while the small cell size of MPB (mostly pennate diatoms and cyanobacteria < 50 µm) makes measurement of primary productivity difficult.
We shall employ a multi-pronged approach with the help of stable isotope tracers to (1) characterise the MPB community in tropical mangrove forests in a diverse range of environments; (2) assess their
abundance and in-situ productivity; (3) determine their significance as a carbon source to the mangrove macrobenthos and as a component of the ecosystem carbon pool; and (4) assess the role it plays in DIC dynamics and sediment CO2 emission. Our findings will fundamentally revise the current carbon budget and the trophic model of mangrove ecosystems.
Measuring sediment CO2 flux in a mangrove plantation at Matang, Malaysia – a natural sauna.
The Mai Po Marshes, a Ramsar wetland in the centre of the world’s largest megalopolis – the Greater Bay Area of 70 million people.
Periophthalmus modestus is a common species of mudskipper found in Hong Kong mangroves.
The mangal stand at Ting Kok is the fourth largest in Hong Kong, and one of the most easily accessible - it is located right next to the main road.
Measuring the effectiveness of mangrove roots in ameliorating hydraulic energy using a flume tank. Small-scale replicas of real-life mangrove roots (Rhizophora stylosa) were constructed using 3D scanning and printing. Note the difference in water level before and after the mangrove roots.
The microphytobenthos (MPB) is an assemblage of photosynthetic unicelullar microalgae and cyanobacteria that live on or near the surface of sediment.