Responses of Functional Traits of Macrobenthic Communities to Human Activities in Daya Bay (A Subtropical Semi-Enclosed Bay), China

Yiyong Rao,Xinwei Chen,Lizhe Cai,Honghui Huang,Xiping Zhou,Sujing Fu

doi:10.3389/fenvs.2021.766580

Abstract

The biological trait analysis (BTA) is regarded as a promising approach to unravel how ecosystem functions respond to human-induced disturbances. This study considered the four sampling locations associated with different human activities in Daya Bay, that is, the domestic and industrial sewage discharge area (SED), mariculture area (MRC), nuclear power plants thermal discharge area (NTD), and an area with relatively low human disturbance as a reference (REF). Thirty modalities of nine traits were selected in BTA. Our results showed a clear shift in the functional structure of macrobenthic communities between the sampling locations, except for the case between NTD and REF. The trait composition in the communities did not highlight any seasonal patterns. Bioturbation, longevity, tolerance, body size, feeding habit, and environmental position were the key traits to characterize the functional structure of macrobenthic communities and demonstrated predictable responses along the environmental gradients. Water depth, DO, Chl-a, NH4+, and petroleum contaminants in sediments were the main variables influencing the trait composition. In addition, the taxonomic index (H′) and functional diversity index (Rao’s Q) showed clear differences among the sampling locations. Although there were no significant differences between NTD and REF in terms of the trait composition and functional diversity, a potential function loss in NTD still can be detected through the integrated analysis with taxonomic diversity. We suggest that the traits (except for fragility, larval development, and living habits) selected and the diversity indices (H′ and Rao’s Q) could serve as promising indicators of ecological conditions in Daya Bay.

Highlights

Macrobenthic fauna are key components in marine ecosystems and drive important processes such as sediment reworking, bio-irrigation, nutrient cycling, and organic matter decomposition (Widdicombe et al, 2004; Lindqvist 2014; Bonaglia et al, 2017)
Compared with the stations in sewage discharge area (SED) and mariculture area (MRC), the stations in nuclear power plants thermal discharge area (NTD) and REF had higher values of water depth and salinity, whereas they showed a lower content of petroleum contaminants (PCs) and Hg in sediments (p < 0.05)
SED showed a higher concentration of chlorophyll a (Chl-a) than the other sampling locations (p < 0.05) and a higher content of total organic carbon (TOC) in sediments than MRC

Summary

Introduction

Macrobenthic fauna are key components in marine ecosystems and drive important processes such as sediment reworking, bio-irrigation, nutrient cycling, and organic matter decomposition (Widdicombe et al, 2004; Lindqvist 2014; Bonaglia et al, 2017). Biodiversity and how it is related with environmental change and ecosystem health have often been measured and quantified through taxonomy-based approaches, which include taxonomic diversity indices and multivariate methods, based on species richness, abundance, and biomass (Vandewalle et al, 2010; Strong et al, 2015). These approaches do not take ecosystem functions into account and ignore that different species may perform similar functional roles in communities and ecosystems (Frid et al, 2000; Dolédec and Bonada 2013). Since the beginning of this century, the trait-based approach, characterizing organisms by a suite of functional identities (functional traits), has received an increasing recognition in the marine community ecology (Bremner et al, 2003; Gagic et al, 2015; Barton et al, 2016; Beauchard et al, 2017; Degen et al, 2018)

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Discussion

Conclusion