Assessing the Ecological Sensitivity of Coastal Marine Ecosystems: A Case Study in Xiamen Bay, China

Characterization of oil exposure parameters affecting impact, recovery, and reestablishment of mangrove forests: Lessons learned

The recovery and reestablishment times of mangrove forests exposed to oil are highly dependent on the oil type and oil-related contaminant levels in water and sediments, spill magnitude, oil exposure duration and frequency, duration of the oil contamination remaining in water and sediments, and post-spill events and clean up actions. Estimating the adverse effects of oil exposure and recovery times of mangrove forests is often done by referencing other spills in different geographical regions or locations with different coastal and environmental characteristics. As a result, these projections may not provide reliable estimates for recovery times and the success of the recovery efforts. A systematic methodology is needed to categorize the prespill conditions and oil exposure vulnerability of mangrove forests. The objectives of this review are to: 1) emphasize the need for a systematic process to document the pre- and post-spill characteristics of mangrove forests, 2) identify key factors that influence the vulnerability of mangrove forests to oil exposure, 3) highlight the differences in mangrove forest characteristics and types of spilled oil to develop effective recovery strategies, 4) emphasize the importance of developing a recovery estimation tool to project the adverse effects of oil spills and recovery times, considering geographical features, mangrove characteristics, and the nature of the spilled oil, and 5) stress the necessity for using appropriate monitoring tools for systematically tracking the recovery of mangrove forests after exposure to oil.

Simulation of mangrove suitable habitat in the Guangdong-Hong Kong-Macao Area under the background of climate change

Climate change has resulted in great influence on the geographical distribution of species. Mangrove forests are one of the most precious ecosystems on the planet, yet they are being threatened by the habitat destruction and degradation under the situation of global warming. Seeking suitable areas for planting mangroves to tackle climate change has been gradually popular in ecological restoration. In this study, we applied the Maximum Entropy algorithm to assess the contribution of environmental factors on mangrove distribution, simulated mangrove suitable habitat for present and future (scenario of SSP245-2070s), and used kernel density analysis for identifying priority of mangrove reserve construction. Results indicate that mean diurnal range and elevation made the highest contribution on mangrove distribution. At present, the mangrove habitat suitability along the western coast of the Guangdong-Hong Kong-Macao Area (GHMA) was the highest while that along the eastern coast was the lowest. By 2070s, mangrove suitable areas would show a decreasing trend under SSP245 scenario. High suitable areas (HSAs) would change fastest and shift to northeast in the same direction as dominant environmental factors. For further mangrove restoration, it is advisable to select sites with high suitability density in the future but low reclamation density at present as prior mangrove reserves, and these sites distribute along the northeastern and northwestern coast of Zhanjiang, Yangjiang and Jiangmen, the Pearl River Estuary and Honghai Bay of Shanwei. Meanwhile, regions with lower suitability density but higher reclamation density could be listed as secondary mangrove reserves.

Revealing the Effectiveness of Fisheries Policy: A Biological Observation of Species Johnius belengerii in Xiamen Bay

The rapid development of China’s economy has brought tremendous pressure to the marine ecosystem, and about 57% of marine fish populations have been overexploited or collapsed. A series of fisheries policies have been implemented successively to improve the decline of resources. Over the past decade, the fisheries sector has particularly increased focus on resource and ecosystem sustainability, which has led to the wider use of stock management policies in China. Therefore, fishery resource assessment is crucial, such as assessing the long-term changes in biological information. This study is based on biological characteristics of Johnius belengerii captured by bottom trawls in Xiamen Bay during two periods, beginning in 2006 and 2016. Length composition, length–weight relationship, growth, mortality, sexual maturation, and feeding intensity were analyzed. The changes in biological characteristics show that there is a phenomenon of improvement in the later period, of which the changes are closely related to a series of fisheries management strategies, such as setting closed fishing periods and non-fishing areas, and establishing fishery restoration marine protected areas. This result seems to reveal the effectiveness of a long-term series of fisheries policies. It can provide an important basis and visibility for management effectiveness.

A Study on Developing Marine Space Planning as a Transboundary Marine Governance Mechanism—The Case of Illegal Sand Mining

Kinmen’s coastline has gradually retreated in recently years, which has resulted in changes in coastal landforms. Research shows that possible factors are ocean currents, monsoons, tides, coastal development, and other anthropic factors such as unauthorized sand mining in the sea area between Kinmen and Xiamen. This study utilized a literature analysis, data collection, in-depth interviews, a field study, and expert opinion in order to establish a managing mechanism for marine spatial planning (MSP) for the sea area between Kinmen and Xiamen. To achieve the goal, the study analyzed law enforcement capacity in the sea area between Kinmen and Xiamen and explored how Taiwan and China can shelve sovereignty disputes and make a workable action plan for cooperating in maritime law enforcement based on a pragmatic and reciprocal principle. Finally, the study proposed to build an MSP-based managing mechanism that can be jointly operated by Kinmen, Xiamen, Zhangzhou, and Quanzhou, because they belong to the same sea area. The results of this study can provide information on marine issues encountered in the governance of countries surrounding seas, such as the marine pollution problems of the countries surrounding the Baltic Sea and Mediterranean Sea.

Evaluating the Effects Related to Restocking and Stock Replenishment of Penaeus penicillatus in the Xiamen Bay, China

The quantitative evaluation of restocking and stock replenishment is essential for providing operational feedback and implementing adaptive management for future restoration projects. Since 2010, approximately 700 million juvenile shrimp (Penaeus penicillatus) have been released into Xiamen Bay, Fujian Province, China, each year, through stock replenishment programs. The recruited shrimp were sampled through three-year bottom trawl surveys from 2014 to 2017. The biological characteristics and catch equation were used to evaluate the effect of restocking and stock replenishment. The analysis uses the FAO-ICLARM Stock Assessment Tool (FISAT II) program. In general, there are two sources of recruitments—one from spawning brood stock and the other from released juvenile shrimp. We constructed an evaluation model for an effect evaluation based on Baranov’s catch equation to separate the initial recruitment volume using survey data. The relationship between body weight and total length was W = 1.638 TL2.9307. There is no statistically significant difference between males and females. The von Bertalanffy growth parameters derived for prawns, using FiSAT II, were L∞ = 209.6 mm and K = 0.51 per year. In spring 2014, the initial resource amount was 49,200, while the ratio of effective recruitment and parent amount was 3.92. The survival rate of the released shrimp larvae, 1.88‱, seems to be very unsatisfactory. The resource amount in summer and autumn is higher than in winter and spring. Obviously, the restocking effect is lower and the programs need to be improved. To improve the restocking effect, the replenishment performance should be adjusted to reduce the mortality rate and increase its release effectiveness. Therefore, corresponding implementations are recommended, including standard extensive culture, reduction in stress during transportation, and temporary culture.

Risk assessment of potentially toxic elements accumulated in fish to Indo-Pacific humpback dolphins in the South China Sea

Indo-Pacific humpback dolphins (Sousa chinensis) reside in shallow coastal waters where they are exposed to potentially toxic elements (PTEs) through dietary intake. We quantitatively assessed the risk posed by eight PTEs to the health of S. chinensis by determining their concentration in 13 fish species. The fish species represented the primary prey of S. chinensis in the South China Sea. Zn and Mn were the most dominant elements in fish at all sampling locations with concentrations ranges of 19.93-67.63 mg kg ^-1 dry weight (dw) and 1.52-68.2 mg kg ^-1 dw, respectively. The highest Zn concentration in fish was found in Coilia mystus (72.65 mg kg^-1 dw) followed by Liza carinatus (62.57 mg kg^-1 dw). At Jiangmen, Zn concentration was significantly lower in benthopelagic fish than in pelagic fish (p < 0.05, one-way ANOVA), while no significant difference was observed in other metals. The health risk posed by dietary intake assessed using the toxicity reference value showed that PTEs did not significant health risk to S. chinensis. In contrast, the risk quotient (RQ) based on reference doses ranged from 2.17 to 54.63 in prey fish that were contaminated with Zn and Cr indicating a potential health risk to S. chinensis in the South China Sea. The number of PTEs that posed a health risk varied between sites with seven out of eight PTEs above threshold at Jiangmen and six out of eight at Zhanjiang and Qinzhou. This study showed fish niche and location may influence the health risk posed by consumption of PTE-contaminated fish.