Distribution of free–Living marine nematodes along environmental gradients in the strait of hormuz

Understanding the drivers of nematode community structure in subtidal ecosystems is critical for assessing marine biodiversity and ecosystem health. As sensitive bioindicators of environmental change, marine nematodes provide crucial insights into ecosystem dynamics; however, their spatial distribution patterns in the Persian Gulf's subtidal zones remain poorly understood. This study investigates the spatial variability of free–living nematode communities across five distinct transects in this understudied region. A total of 2189 specimens, representing 60 different genera, were identified. Nematode density showed significant variation, ranging from 16.7 to 92.6 individuals in 10 cm², with the highest densities typically found at the shallowest stations. The average number of genera per sample ranged from 1 to 18.67. The Shannon diversity indices varied significantly, with a maximum of 2.58 and a minimum of 0, while evenness scores ranged from 0.76 to 1. Notable differences in nematode community structure were observed across the various transects and stations. The overall nematode community was dominated by genera such as Actinonema, Axonolaimus, Dorylaimopsis, Gnomoxyala, Halalaimus, Hopperia, Marylynnia, Pierrickia, Sabatieria, Subsphaerolaimus, and Terschellingia across different transects. According to DistLM analysis, depth, salinity, mean grain size, pH, and temperature together explained 22.9 % of the total variance in the nematode community, with depth accounting for 9.3 % and the other significant variables contributing an additional 13.6 %. Further research is essential to clarify the relationship between nematode communities and environmental conditions in underexplored ecosystems like this region.