3. Food Web Ecology of Soft Shores: A Brief Introduction
Coastal soft-bottom marine habitats such as mangrove forests, tidal flats and shallow sub-tidal sediments play a critical role in providing essential ecosystem services to coastal communities.
One of those services is to support coastal fisheries by acting as nursery grounds and feeding habitats for commercially important species. The fish supported by the productivity provided by their habitats, in turn, supply food to humans and wildlife species of high conservation values such as horseshoe crabs, birds and dolphins. The ability of these habitats to fulfil this supporting role is underpinned not only by their generally high productivity, but also their collective function as connected habitats that allow fish (hereafter including other coastal organisms such as crustaceans) to progress through various larval and juvenile stages in the life cycle, successively utilising the chain of connected habitats.
With consumption of locally generated foods, these life history stages perform a process of ‘trophic relay’ that results in effective transfer of energy from the shallow habitats progressively to support offshore fish production. This trophic connectivity is a critical component of the ecological connectivity that underpin the function and services of coastal marine habitats.
Lee SY, Primavera JH, Dahdouh-Guebas F, McKee K, Bosire JO, Cannicci S, Diele K, Fromard, F, Koedam N, Marchand C, Medelssohn I, Mukherfee N, Record S 2014. Ecological role and services of tropical mangrove ecosystems: a reassessment. Global Ecology and Biogeography 23:726-743
Food web dynamics, namely, the pattern of food production and their transfer among organisms, is a key function underpinning all ecosystems. The magnitude, direction and efficiency of energy transfer not only defines key functional elements of the ecosystems but also determines ecosystem properties such as stability and capacity for goods and services (e.g. fishery production) to mankind. As such, understanding the food web structure and dynamics are clearly vital in the conservation and management of our ecosystems.
Conventional approaches to conservation have focused on the survival of individual species, but it is now widely recognised that species survival must depend upon functional ecosystems. To this end, the International Union for the Conservation of Nature (IUCN), for example, has recently promoted a new major initiative called the Red List of Ecosystems to assess the vulnerability of ecosystems around the world.
The typical food web of Hong Kong's soft shores: