Dual isotope (δ¹³C, δ¹⁵N) plots of estuarine primary producers (crosses) and predicted fractionation associated with one trophic level for Tairua and Whangapoua estuaries.

<p><i>Dosinia subrosea</i> (foot muscle) from site 1 closest to the estuary mouth are presented as solid circles and from site 9 as empty circles. For comparative purposes, the isotope values of a suspension-feeding bivalve, <i>Austrovenus stutchburyi</i>, within each estuary are presented as grey triangles.