Comparison of macrozoobenthic communities and environmental variables in the subtidal zones between a nearly closed bay and an open bay

Abstract

To compare the impact of human activities and geographical environment on macrozoobenthic communities in bays, four season surveys of macrozoobenthos and environmental variables in Kaozhou Bay (a nearly closed bay) and Honghai Bay (an open bay) were conducted. CLUSTER, non-metric multi-dimensional scaling (NMDS) and the relative importance index (IRI) showed that the macrozoobenthic communities were different between Kaozhou Bay and Honghai Bay. The top three dominant species in Kaozhou Bay are brackish species, including Dendronereis pinnaticirris, Euclymene annandalei and Neanthes glandicincta, while the top three dominant species in Honghai Bay are hyperhaline species, including Paraprionospio pinnata, Amphioplus laevis and Aglaophamus dibranchis. Two-way Analysis of Variance (ANOVA) showed that the species number, Shannon-Wiener diversity index, evenness index, richness index, AMBI, M-AMBI, water depth, salinity, and dissolved oxygen in Kaozhou Bay were significantly lower than those in Honghai Bay, while the concentrations of total nitrogen, total phosphorus, silicate, and mercury in Kaozhou Bay were significantly higher than those in Honghai Bay. Principal components analysis (PCA) showed that Kaozhou Bay was associated with higher concentration of total nitrogen, total phosphorus, and silicate, and Honghai Bay was characterized by deeper water, higher salinity, and higher concentration of dissolved oxygen. BIO-ENV analysis showed that water depth was the most important environmental factor affecting macrozoobenthic community in two bays. The above results showed that the species diversity index and richness index of Kaozhou Bay were lower than those of Honghai Bay because of the geographical environment difference between the two bays.