Functional traits and community structure of marine nematodes in the seagrass beds along the eastern coast of Shandong Peninsula, China

Abstract

Seagrass beds ecosystems, which are critical yet declining blue carbon ecosystems worldwide, play crucial roles in terms of biodiversity and carbon sequestration. Free-living marine nematodes are useful biological indicators of various environmental disturbances. The functional traits and community structure of free-living marine nematodes were studied in seagrass beds (SG) and the neighboring unvegetated seabeds (SB) in three temperate bays along the eastern coast of Shandong Peninsula, China. The nematode abundance was 896.9 ± 382.0 ind./10 cm² in spring and 823.0 ± 576.8 ind./10 cm² in autumn. In total, 181 nematode species were identified, including 101 genera and 30 families. Seagrass beds had higher species richness (114 species in SG vs. 95 species in SB) and supported more ‘persister’ nematodes (longer-lived, slower-reproducing species), whereas SB favored ‘colonizer’ species (fast-reproducing, short-lived). Redundancy analysis identified temperature and chlorophyll-a as primary drivers of community structure, with sediment grain size and phaeophytin-a further explaining 64.9 % of the variation in functional traits. Seagrass rhizome systems enhanced sediment stability and organic enrichment, thus supporting epigrowth feeders. These results indicated that seagrass beds are important for maintaining coastal benthic biodiversity, decreasing environmental degradation, and, therefore, facilitating coastal management.