Food web dynamics in the mangrove ecosystem of the Pearl River Estuary surrounded by megacities

Global recognition that mangroves support coastal ecosystem services has increased; however, studies on trophic dynamics in mangrove ecosystems remain limited. We seasonally analysed the 613C and 615N of 34 consumers and 5 diets to elucidate the food web dynamics in the Pearl River Estuary (PRE). Fish had a large niche space during the monsoon summer, reflecting increased trophic roles. In contrast, the small niche space of benthos over seasons reflected consistent trophic positions. Consumers mainly utilized plant-derived organic matters in the dry season and particulate organic matters in the wet season. The present study with literature reviews revealed characteristics of the PRE food web with the depleted 613C and enriched 615N, indicating a high contribution of mangrove-derived organic carbon and sewage input, particularly in the wet season. Overall, this study confirmed the seasonal and spatial trophic dynamics in mangrove forests surrounding megacities for future sustainable mangrove ecosystem management.

Automated summary

Global recognition of the importance of mangroves in supporting coastal ecosystem services has increased, but research on trophic dynamics in mangrove ecosystems remains limited. This study analyzed stable isotopes in consumers and diets in the Pearl River Estuary to examine food web dynamics. The study found that fish had a larger niche space during the monsoon summer, indicating increased trophic roles. Benthos had a small niche space across seasons, indicating consistent trophic positions. The study also identified the use of different organic matters by consumers in different seasons. This study provides important insights into the seasonal and spatial trophic dynamics in mangrove forests, which can inform sustainable management of these ecosystems.