Assessment of Carbon Storage of Reef Fish in Shique Beach Marine Ranching Based on Grey-Markov Model

Abstract

At present, the world is still experiencing a climate warming trend, which has severe implications for Earth's sustainable development. Increasing carbon sinks mitigates climate change and improves national and social development through carbon trade. As the largest carbon pool on the planet, the ocean serves as a major carbon sink. The fishery carbon sink is an important part of the ocean carbon sink, which can increase the capacity of aquatic fishery ecosystems to absorb atmospheric CO2. Marine ranching is a typical example of a carbon sink fishery and an effective model for ensuring the sustainability of the carbon sink effect of aquatic fishery ecosystems. Despite the fact that marine ranching plays an important role in enhancing the carbon capacity of fishery carbon sinks, there have been few studies on marine ranching carbon storage. Reef fish species are the target population for marine ranching conservation and enhancement and are the most typical biological community of an artificial reef ecosystem, with substantial ecological and economic benefits. Reef fish species have an important influence on the carbon cycling, deposition, and removal processes in the ocean. It is one of the key carbon storage components of the marine ranching carbon sink. However, there are currently only a few studies on the carbon storage capacity of reef fish. Therefore, estimating and predicting the carbon storage of reef fish are useful for assessing the carbon sink potential and formulating a stock enhancement strategy for reef fish based on the carbon sink target. Based on this, we conducted research on five species of reef fish. On the one hand, we determined the carbon content of reef fish and used the standing biomass of reef fish harvested by cage nets from Shique Beach marine ranching in April 2017, January 2018, May 2019, and December 2020 to estimate the carbon capacity of reef fish in the artificial reef area and contrast areas in spring 2017, winter 2018, spring 2019, and winter 2020. On the other hand, we used the Grey-Markov model, a prediction model that we initially employed in a fishery study, to predict the carbon potential of reef fish in the artificial reef area in spring 2021, winter 2022, spring 2023, and winter 2024. The results showed that the mean carbon contents of dry reef fish samples were 42.95%~50.19% and that the mean carbon contents of fresh reef fish samples were 11.05%~13.25%. The standing biomass carbon storage of reef fish decreased on a regular basis in reef areas, whereas it fluctuated in contrast areas. The standing biomass carbon storage values of reef fish in the reef area in spring 2017, winter 2018, spring 2019, and winter 2020 were 293.46 t, 104.49 t, 119.40 t, and 48.48 t, respectively. This equates to approximately 0.73 × 104~4.40 × 104 USD carbon sink economic value. The standing biomass carbon storage values of reef fish in contrast areas in spring 2017, winter 2018, spring 2019, and winter 2020 were 21.64 t, 59.07 t, 6.73 t, and 0 t, respectively. Reef fish in reef areas had much higher standing biomass carbon storage values than those in contrast areas. The average relative error of the validation data of the Grey-Markov model was 8%, which was 12% better than the prediction accuracy of the GM(1, 1) model; therefore, we were able to fully demonstrate the superiority of the Grey-Markov model for accurate short-term prediction of the carbon storage of reef fish. The standing biomass carbon storage values of reef fish in reef areas in spring 2021, winter 2022, spring 2023, and winter 2024 were 64.84 t, 49.84 t, 25.28 t, and 19.43 t, showing a decreasing trend. In summary, reef fish species have a strong carbon storage capacity and a high ecological value, which give them an important role in fishery carbon sinks. However, the carbon storage capacity of reef fish is expected to decline in the future, which may be related to their overexploitation. Reef fish species are the primary targets of traditional fisheries. Therefore, we can take the following measures: First, we should consider the carbon storage effect of reef fish; Second, marine ranching operators can strengthen their investment in the construction of artificial reef areas and conduct active stock enhancement of reef fish, which can increase reef fish resources and subsequently reef fish carbon storage. Third, we can strengthen the environmental protection and management of marine ranching. The findings of this study not only provide a basis for assessing the carbon storage potential of reef fish but also serve as a scientific reference for establishing a strategy to develop reef fish resources in marine ranching based on fishery carbon sinks.

Keywords

• marine ranching
• reef fish
• carbon storage
• gm(1, 1) model
• grey-markov model