Isotopic evidence for spatial heterogeneity in trophic levels within benthic food webs across typical habitats along the coast of the eastern Laizhou Bay, China.

Abstract

This study employed stable isotope analysis (δ¹³C and δ¹⁵N) to examine the trophic sources, nutritional levels of consumers, and ecological niches of macrobenthic organisms across four distinct habitats, including artificial reef area (ARA), marine protected area (MPA), bottom seeding proliferation area (BSPA), and seagrass bed (SGB) in Laizhou Bay during spring and autumn. The results indicate that in spring, the δ¹³C values of particulate organic matter (POM) (-23.44 ± 0.30) and phytoplankton (-21.50 ± 0.65) in ARA, as well as the δ¹⁵N values of zooplankton (10.20 ± 1.21) and POM (6.57 ± 1.35) in autumn, were significantly higher than those in other regions. The diet of polychaetes (the dominant functional group) in ARA shifted from phytoplankton (34.6 %) in spring to zooplankton (59.3 %) in autumn. Regarding trophic niche area (TA), BSPA exhibited the largest value in spring (TA = 43.29), whereas ARA showed the highest value in autumn (TA = 22.53), with SGB displaying the smallest TA. Specifically, in the spring, the TA content in BSPA was 5.6 times higher than that in SGB, while in the autumn, the TA content in ARA was 3.5 times higher than that in SGB respectively. Comparative analyses among habitats suggest that habitat heterogeneity and seasonal dynamics jointly regulate trophic structure through resource partitioning and consumer adaptation. Furthermore, the artificial reef demonstrated elevated trophic levels and more complex trophic linkages, confirming its role in enhancing short-term ecosystem functioning via resource diversification. These findings highlight the importance of maintaining habitat diversity in coastal management and support the strategic deployment of artificial habitats to promote rapid ecological recovery.