Fig. 7.1.

Hypothetical examples of stable isotope data from a tropical estuarine food web with three main food chains, one based on mangroves, one on phytoplankton and one on seagrass. It is possible to trace material transfer through three trophic links, from primary producers (trophic level (TL) 1) to tertiary consumers (TL 4), if considering the average trophic discrimination factors of +1.1‰ for δ13C and +2.8‰ for δ15N, as appropriate for non-acid treated muscle tissue (McCutchan et al. 2003). *For the phytoplankton to zooplankton link, trophic discrimination factors of –0.2‰ for δ13C and +1.1‰ for δ15N were used, assuming zooplankton samples were acidified and analysed whole (McCutchan et al. 2003). Symbols courtesy of the Integration and Application Network, University of Maryland Center for Environmental Science (ian.umces.edu/imagelibrary/).