Multiple-biomarkers show the importance of blue carbon to commercially important fishery species

Coastal blue carbon ecosystems (BCE) support nearshore food webs and provide habitat for many commercially impor-tant fish and crustacean species. However, the complex links between catchment vegetation and the carbon food-base of estuarine systems are difficult to disern. We employed a multi-biomarker approach (stable isotope ratios -813C and 815N, fatty acid trophic markers - FATMs and metabolomics - central carbon metabolism metabolites) to test links be-tween estuarine vegetation and the food sources available to commercially important crabs and fish occurring within the river systems of the near-pristine eastern coastline of the Gulf of Carpentaria, Australia. Stable isotope analysis con-firmed the dietary importance of fringing macrophytes to consumer diet, but showed that this is modulated by their dominance along the riverbank. FATMs indicative of specific food sources further confirmed the differences among upper intertidal macrophytes (driven by concentrations of 16: 1co7, 18:1co9, 18:2co6, 18:3co3 & 22.0) and seagrass (driven by 18:2co6, 18:3co3). These dietary patterns were also reflected in the concentration of central carbon metab-olism metabolites. Overall, our study demonstrates the congruence of different biomarker approaches to resolve bio-chemical links between blue carbon ecosystems and important nekton species, and provides fresh insights into the pristine tropical estuaries of northern Australia.

Automated summary

A study of river systems in the eastern coastline of the Gulf of Carpentaria, Australia, reveals the importance of riparian vegetation in supporting nearshore food webs and commercially important fish and crustacean species. Through the use of stable isotope analysis and fatty acid trophic markers, the study demonstrates the links between estuarine vegetation and the dietary sources available to these species, providing new insights into the pristine tropical estuaries of northern Australia.