Food web analysis of an eelgrass (Zostera marina L.) meadow and neighbouring sites in Mitsukuchi Bay (Seto Inland Sea, Japan) using carbon and nitrogen stable isotope ratios

The contribution of benthic microalgal production has been compared both within and outside a coastal eelgrass (Zostera marina L.) meadow. Carbon and nitrogen stable isotope ratios of suspended particulate organic matter (POM), epiphytic and epilithic organic matter (EOM), leaves of Z. marina (inside the meadow only) and two secondary consumer species (small crustaceans and fish) were measured inside and outside a meadow in Mitsukuchi Bay, Northwest Seto Inland Sea, Japan. Inside the meadow, primary producers (epiphyton) and consumers showed higher δ13C signatures than outside. Primary and secondary consumers inside the meadow were mainly dependent on epiphyton on the leaves of Z. marina, while consumer species outside the meadow were basically dependent on epilithon.