Integrating Taxonomic and Functional Responses of Free-Living Marine Nematodes for Coastal Pollution Assessment and Ecosystem Health Monitoring

Abstract

Free-living marine nematodes are widely used as bioindicators, yet comparative studies integrating taxonomic, functional, and multivariate community responses across pollution gradients remain limited. This study evaluated changes in nematode assemblage responses along a regional coastal disturbance gradient and investigated their applicability for ecological monitoring. Fifteen sampling stations were classified into high, intermediate, and low disturbance levels. The nematode assemblages were studied at the genus level through diversity indices, trophic guild structure, c-p strategy, and functional diversity. High-disturbance sites showed significant reduction in genus richness, Shannon diversity, and Maturity Index compared with low-disturbance reference sites. Opportunistic bacterivores and c–p 1–2 group taxa, particularly members of Xyalidae and Comesomatidae, dominated highly disturbed assemblages, while predator–omnivore taxa declined from 18% at low-disturbance sites to 4% at high disturbance sites. Functional richness and Rao’s quadratic entropy had more significant reductions than taxonomic diversity, where the functional trait space of severely disturbed sites was 23% that of reference sites. Multivariate analyses further indicated strong associations between nematode community restructuring and environmental disturbance. Overall, the findings indicated that the inclusion of functional trait metrics with the Maturity Index can enhance sensitivity and ecological interpretation of nematode-based coastal pollution assessment and monitoring of ecosystems. These results demonstrate that the functional trait-based approach provides enhanced sensitivity for determining ecological damage compared with traditional taxonomic indicators. Integrating the maturity index measurement with the functional trait approach in the monitoring strategy is thus effective and feasible in coastal pollution assessment and management.