Field Manipulative Experiment
The natural abundance analysis will be complemented by enriched isotope experiments.
By artificially manipulating the abundance of the heavy isotope (13C and 15N), difference in uptake by different producers (e.g. fast uptake by microalgae but slow uptake by mangrove trees due to difference in tissue turnover rates) will result in differential labelling of the producers, thereby allowing tracking of specific food sources when the consumers are analysed some time after enrichment.
This approach can be used to assess the impact of artificial disturbance (i.e. fishing efforts of clam collectors) of the substrate on the food web dynamics.
Resilience (resistance to future disturbance) of the community can then be assessed by applying a second round of disturbance and comparing the response of previously disturbed and undisturbed areas. Disturbed areas are expected to have lower resilience.
Spraying 13C enriched isotopic compound on the surface of the sampling quadrat.
Collecting samples in the enrichment quadrat on Mai Po mudflat.
Two tired RAs each carrying 70kg of samples from 2 enrichment plots at Ting Kok.