Ecological carrying capacity and carbon sequestration potential of bivalve shellfish in marine ranching: A case study in Bohai Bay, China

Abstract

IntroductionShellfish play an important role in ecological restoration and as carbon (C) sinks, but studies on their ecological carrying capacity (ECC) and C sequestration potential are sparse.MethodsIn this study, we selected a 57-hectare artificial oyster reef in a typical marine ranching in Bohai Bay, China, to evaluate the ECC and their C sequestration potential of bivalve shellfish, and projecting their impact on functional groups in the system, with an Ecopath with Ecosim (EwE) food web model. We conducted four biological surveys to obtain the biomass measurements, with one conducted in each of the summer, autumn, and winter of 2019 and one in the spring of 2020; and the functional groups included in the surveys comprised fish, cephalopods, crustaceans, snails, bivalve shellfish, annelids, other macrobenthos, meiobenthos, starfish, sea cucumbers, zooplankton, phytoplankton, and detritus.Results and DiscussionThe EwE model prediction results showed that the ECC of bivalve shellfish was established to be 282.66 t/km2, far more than the existing quantity of 187.76 t/km2. Therefore, at present, the ecosystem of the study marine ranching is not yet mature. Moreover, our ecological network analysis parameters indicated that the marine ranching ecosystem will be mature and stable when the bivalve shellfish population reaches its ECC. However, the increase in bivalve shellfish biomass will result in a decrease in the population sizes of species competing for food resources with bivalve shellfish, mainly gobiid fish such as Tridentiger bifasciatus, Tridentiger trigonocephalus, Tridentiger barbatus. Simultaneously, when the bivalve shellfish reach their ECC, 29.23 t of CO2 can be sequestrated by bivalve shellfish, comprising 14.32 t being removed from the ecosystem as prey and 14.91 t being stored on the seafloor through biodeposition.ConclusionTherefore, the research demonstrated that, within the scope of ECC, the increasing bivalve shellfish can improve the C sequestration capacity of the marine ranch ecosystem, and effective management of bivalve shellfish in marine ranching can improve the economic benefits and C sink service functions of marine ranching.

The Effect of Marine Pastures on Green Aquaculture in China

“…At present, the relevant research studies on marine pasture in China are gradually becoming mature, from the hard environment to the soft environment, from the site selection of marine pasture [12,13], properties of algal reef materials [14,15], and spatial layout [16,17] to modern marine pasture construction [15], ecological security assessment [18][19][20], and research on the key technologies of marine pasture [21,22]; from the emphasis on economic benefits to the consideration of both economic and ecological benefits, the analysis of potential economic benefits [23,24] to ecological benefits [25,26], and the measurement of comprehensive benefits [27,28]. In recent years, with the "two mountains theory" and the "two-carbon target" successively proposed, the academic community has focused on topics such as carbon sinks in marine pastures and fisheries [29,30], most scholars have measured the blue carbon sink with marine shellfish and algae as objects [31,32], and some scholars have also started from carbon sink pricing and incentive subsidies [33,34].…”