Potential role of scallops Argopecten irradians in deposition of particulate nutrient and trace elements in a eutrophic estuary, northern China

F Wang,P Liu,P Wang,Y Zhou,S Xu

doi:10.3354/aei00258

Abstract

Anthropogenic inputs of nutrients and trace elements have globally significant impacts on coastal waters. In order to evaluate the effect of the filter-feeding bay scallop Argopecten irradians on benthic-pelagic coupling in a eutrophic estuary (Laizhou Bay), biodeposition of total suspended materials, particulate nutrient (C, N, P) and trace elements (Cu, Zn, Pb, Cr, Cd, Hg, As) were determined using modified sediment traps during autumn 2013. Results showed that biodeposition rates of the bay scallops were rather high compared with those reported for other bivalves. The allometric relationship between the biodeposition rate (BDR; g ind.(-1) d(-1)) and soft tissue dry weight (W; g ind.(-1)) was modeled (BDR = aW(b)) with the value of a being 1.24 in September and dropping to 0.96 in October. The biodeposition contributed to the enrichment of organic matter, C and N in the local sediment. Trace element concentrations in the scallop biodeposits were significantly higher than those of the natural surrounding sediments, especially during the months of October and November. A. irradians significantly increases the mass fluxes from the water column to the bottom, with estimated 1140 tonnes of total suspended material being deposited to the seabed each day in the culture zone. Results also suggest that biotransformation and biodeposition by such efficient filter-feeders may play a pivotal role in the fate and transportation of particulate nutrient and trace elements in aquatic ecosystems. In coastal waters and estuaries subject to anthropogenic inputs, suspended bivalve aquaculture could be environmentally advantageous via intense filtering and biodeposition, potentially mitigating eutrophication trace and element pressures.

Highlights

Oceans, especially their coastal waters and estuaries, have been strongly affected by numerous human activities (Halpern et al 2008), and these impacts are projected to increase over the few decades (Doney 2010)
Our results showed that the biodeposition rates of the bay scallop Argopecten irradians increased allometrically with flesh weight in temperate seasons when water temperatures ranged between 16 and 24°C
This study demonstrated that the bay scallop biodeposition rates in Laizhou Bay were rather high (1.24 g [g tissue dry weight (DW)]−1 d−1) and fall within the upper range reported previously for other filter-feeding bivalves (0.042 to 2.25 g [g tissue DW]−1 d−1; Table 9 and references therein)

Summary

Introduction

Especially their coastal waters and estuaries, have been strongly affected by numerous human activities (Halpern et al 2008), and these impacts are projected to increase over the few decades (Doney 2010). Through filtration and deposition of suspended particulate matter, intensive bivalve populations can exert a top-down control on phytoplankton biomass, resulting in alterations to the benthic environment and benthos composition (Grant et al 1995, Crawford et al 2003, Callier et al 2007). With a worldwide concern for the increase in waters impacted by eutrophication and trace element contamination, some researchers have suggested that the dramatic growth in bivalve mariculture could mitigate, or even biologically control the pollution of coastal waters (e.g. Zhou et al 2006a, Stadmark & Conley 2011, Petersen et al 2014, Nielsen et al 2016, Grizzle et al 2017, Filgueira et al 2017)

Objectives

Methods

Results

Discussion

Conclusion