Burial fluxes and source apportionment of carbon in culture areas of Sanggou Bay over the past 200 years

Abstract

In this study, we assessed the burial fluxes and source appointment of different forms of carbon in core sediments collected from culture areas in the Sanggou Bay, and preliminarily analyzed the reasons for the greater proportion of inorganic carbon burial fluxes (BF TIC ). The average content of total carbon (TC) in the Sanggou Bay was 2.14%. Total organic carbon (TOC) accounted for a small proportion in TC, more than 65% of which derived from terrigenous organic carbon (C t ), and while the proportion of marine-derived organic carbon (C a ) increased significantly since the beginning of large-scale aquaculture. Total inorganic carbon (TIC) accounted for 60%-75% of TC, an average of which was 60%, with a maximum up to 90% during flourishing periods (1880-1948) of small natural shellfish derived from seashells inorganic carbon (Shell-IC). The TC burial fluxes ranged from 31 g/(m 2 ·a) to 895 g/(m 2 ·a) with an average of 227 g/(m 2 ·a), which was dominated by TIC (about 70%). Shell-IC was the main source of TIC and even TC. As the main food of natural shellfish, biogenic silica (BSi) negatively correlated with BF TIC through affecting shellfish breeding. BF TIC of Sta. S1, influenced greatly by the Yellow Sea Coastal Current, had a certain response to Pacific Decadal Oscillation (PDO) in some specific periods.

Biogeochemical Characteristics of Sedimentary Organic Matter in Coastal Waters of a Mariculture Area: The Big Impact of Bay Scallop Farming

“…In any case, this result directly confirms the important role of large-scale scallop farming in the accumulation of SOM [4,8,36]. Similar observations were also documented by Liu et al [19] and Zhou et al [87] in Sangou Bay and Daya Bay, China. Moreover, interestingly, it was also found that the scallop culture in this study seemed to promote the burial of terrestrial OC in the sediments of core H3 (Figure 6e), which may be related to the decomposition mode of SOM, e.g., priming effect, but the specific mechanism needs further research.…”

“…In this study, the sedimentation rates in the SFA, 0.88-0.90 cm yr −1 , were at a relatively high level, significantly higher than those observed in the central Bohai Sea (0.094-0.17 cm yr −1 ) and the coastal waters of the East China Sea (<0.2 cm yr −1 ), and comparable to those observed in other Chinese aquaculture areas along the west coastline of the Yellow Sea, e.g., Sanggou Bay (0.66 cm yr −1 ) and Jiaozhou Bay (0.64-1.74 cm yr −1 ) [19,[73][74][75][76][77][78].…”

“…Generally, marine algae, terrestrial C3 plants, and shellfish biodeposits are the main sources of SOM in shellfish farming areas [8,19]. This study estimated the proportion of different sources of SOM based on a δ 13 C and δ 15 N three-end-member mixing model [20] as follows:…”

“…On one hand, metabolic activities of scallops produce a large amount of POM, i.e., feces and fake feces that are mainly composed of undecomposed phytoplankton, which potentially increases the amount of OM with lower carbon to nitrogen (C/N) ratio buried in sediments [8,19,65]. This is why the concentration of TN in the sediments of the SFA was higher than that of the NSFA (Figure 4).…”

Distinct response of total and active fungal communities and functions to seasonal changes in a semi‐enclosed bay with mariculture (Dongshan Bay, Southern China)

“…Marine aquaculture (mariculture) has rapidly expanded over the past two decades and currently provides an essential source of animal protein worldwide (Bouwman et al 2013). Intensive mariculture activities not only influence water quality and biodiversity, but also result in very high burial rates of organic matter in mariculture impacted areas (Liu et al 2015(Liu et al , 2016. Several studies demonstrated severe environmental and biological changes of coastal waters after long-term intensive mariculture activities (Duarte et al 2003;Li et al 2018a;Xu et al 2020a).…”