Meio- and macrofauna as indicators in the ecological monitoring program: Do they behave similarly?

Bivalve aquaculture and land-based pollution increasingly affect benthic ecosystems in Jiaozhou Bay along the southern Yellow Sea coast of China. Meiofauna and macrofauna are key components of benthic communities and are widely used as indicators of ecosystem health, yet their responses to aquaculture impacts and environmental gradients remain poorly understood. This study investigated meiofaunal and macrofaunal community responses to bivalve aquaculture and environmental gradients, evaluated the consistency of their relationships with environmental variables, and assessed their suitability for integrated benthic ecological assessment. During an autumn cruise in 2018, meiofaunal and macrofaunal samples were collected simultaneously at 11 stations across the bay, and community structure, diversity, and functional trait-based indices were analyzed. Meiofaunal assemblages exhibited small-scale spatial variability, reflected in feeding guilds and colonizer-persister (c-p) structures, whereas macrofaunal communities showed broader spatial patterns, with trophic composition and AMBI groups varying among areas. Contrasting ecological conditions were observed at stations J3 and J4, where clam farming (Ruditapes philippinarum) and oyster culture (Magallana gigas) occurred, respectively. Meiofauna indicated moderate to poor ecological conditions, whereas macrofauna indicated relatively better status, with discrepancies at stations J1 and J7. Overall, these results demonstrate scale-dependent and complementary responses of meio- and macrofauna, supporting their combined use in integrated benthic assessment in Jiaozhou Bay.