Spatial and Temporal Distribution of Meiofauna and the Influencing Environmental Factors in Jiaozhou Bay

In order to study the spatial and temporal distribution patterns of meiofauna in Jiaozhou Bay and its influencing environmental factors, two field samplings were carried out in the waters inside and outside Jiaozhou Bay in January and April 2021. The taxon composition, abundance, biomass, community structure, horizontal and vertical distribution of meiofauna, and their relationship with the environmental factors were investigated. The results showed that 12 taxa of meiofauna were identified in the study area. The average abundance of meiofauna in winter and spring was (769.6±184.8) and (683.3±173.3) ind./10 cm², respectively. The average biomass of meiofauna in winter and spring was (587.0±78.0) and (426.7±67.4) μg/10 cm², respectively. Free-living marine nematode was the most dominant taxon, accounting for 87.60% and 92.36% of the total abundance of meiofauna, in winter and spring, respectively. Other important taxa included copepods, rotifers and nauplius. There were significant differences in seasonal distribution of meiofauna community structure. Results of BioEnv analysis showed that the best combination of environmental factors explaining the variation of meiofaunal community structure was water depth, bottom water temperature, sediment water content and median grain size. In terms of horizontal distribution, there were no significant differences in the community structure of meiofauna community inside and outside of Jiaozhou Bay between the two seasons, but the lowest abundance values in each season appeared in the mouth of the bay, which might be related to the sediment median grain size and bottom water temperature. The average abundance of meiofauna in the study area was lower than other areas, which was caused by the offshore human activities. The high values of N/C ratio indicated that there was organic pollution in the study area, which may be due to the bivalve bottom aquaculture in Jiaozhou Bay, resulting in the accumulation of organic matter in sediment environment.