Comparing food web structure and trophic diversity between natural and artificial habitats: a case study in the Bohai Sea, China

Research suggests that complex habitats support greater species variety and abundance, especially for artificial reefs deployed to restore marine habitats and protect coastlines. However, it’s unclear how community trophic diversity and food web trophic structures differ between natural and artificial ecosystems. In this study, we used the Juehua Island area of China’s Bohai Sea to empirically investigate the food web structure and trophic diversity in three marine habitats: seagrass, artificial reefs, and sediment substrates. We used stable isotope analysis to compare their food web structures. We found that δ13C and δ15N of the carbon sources and consumers differed among the habitats. The seagrass trophic group’s δ13C had the largest range (–21.20‰ to − 12.51‰), but the artificial reef habitat had the largest range of mean δ15N values. Lateolabrax japonicus had the highest trophic position in the seagrass bed habitat, versus Gobiidae in the artificial reef habitat and Sebastes schlegelii in the sediment substrate habitat. Diet compositions varied widely based on the mixSIAR model output. The food web’s topological values were highest in the seagrass bed habitat, followed by the artificial reef and sediment substrate habitats. Thus, the artificial reefs promoted food web trophic complexity. The seagrass bed had the greatest trophic diversity and redundancy for the food web and most consumer trophic species. There was high isotopic niche overlap among the three food webs and consumer trophic groups, suggesting potential similarities in resource utilization. Our results will support systematic assessment of the ecological effects of artificial reefs, and deepen understanding of differences among heterogeneous habitats in their ecosystem structure and function.