Trophic shift in young-of-the-year mullets during salt marsh colonization

This study investigated the trophic shift of young-of-the-year (YoY) thinlip grey mullets Liza ramada and golden grey mullets Liza aurata during their recruitment in a salt marsh located on the European Atlantic coast. Stable isotope signatures (δ13C and δ15N) of the fishes followed a pattern, with enrichments in 13C and 15N to increasing length: δ13C in fishes < 30 mm ranged from -19.5 to -15.0‰, whereas in fishes > 30 mm δ13C ranged from -15.8 to -12.7‰, closer to the level in salt marsh food resources. Large differences between the δ15N values of mullets and those of food sources (6.0‰ on average) showed that YoY are secondary consumers, like older individuals, when feeding in the salt marsh. YoY mullets shift from browsing on pelagic prey to grazing on benthic resources from the salt marsh before reaching 30 mm in length. The results highlight the role of European salt marshes as nurseries for juvenile mullets.