FIG 6.

Carbon stable isotope δ-¹³C composition values in Kentrophoros sp. H (this study) and published values for other shallow-water thiotrophic symbioses (5, 37–40), nonsymbiotic benthic animals (5, 60, 61), and two Mediterranean seagrass species (60–63), compared with dissolved inorganic carbon (DIC) from pore water and seawater at Elba (this study). Values for Kentrophoros and Olavius algarvensis (except the “bulk” value) are from direct protein-SIF, and others are from isotope ratio mass spectrometry (IRMS). Values for symbiont-bearing tissue (e.g., gills) are also included under “symbiont.”