Effects of heavy metals and organic matter fractions on the fungal communities in mangrove sediments from Techeng Isle, South China

Abstract

Heavy metal pollution has become a serious environmental problem in mangrove ecosystems and has attracted more attention. Most of previous studies have mainly focused on the effects of heavy metals on bacterial communities in mangrove sediments. This study was the first to investigate the effects of heavy metals (e.g., As, Co, Cr, Cu, Mn, Ni, Pb, V and Zn) and organic matter fractions (including total organic carbon (TOC), total nitrogen (TN), and total sulfur (TS)) on the fungal communities in mangrove sediments from Techeng Isle, South China. The results of this study indicated that the average contents of Mn, Pb and V of 8.30–161.80 μg/g presented relatively higher pollution levels, while the concentrations of Zn, Cr, Cu and Ni of 0.80–21.93 μg/g were lower than those recorded in other mangrove ecosystems. Furthermore, the sediment fungal community structures responded differently to the nine heavy metals and three organic matter fractions. Heavy metals Cr, Pb and V displayed significant positive correlations with Eutypella (P < 0.05), whereas significant negative correlations with Cystobasidium, Lulworthia, Cladosporium, Lulwoana and Cephalotheca (P < 0.05). In addition, the effects of heavy metals and TS on many fungal genera were opposite to those of TOC and TN. Fungal genera that decreased with high TOC and TN contents may be increased with high heavy metal contents and TS, and vice versa, and the genera that increased with high TOC and TN contents may be decreased with high heavy metals and TS. Our results suggested that many heavy metals, such as Cr, Pb and V, were sensitive to several fungal genera in mangrove sediments, and heavy metals together with organic matter fractions may participate and shape the fungal communities in mangrove sediments.