[Seagrass ecosystems: contributions to and mechanisms of carbon sequestration].

The ocean's vegetated habitats, in particular seagrasses, mangroves and salt marshes, each capture and store a comparable amount of carbon per year, forming the Earth's blue carbon sinks, the most intense carbon sinks on the planet. Seagrass meadows, characterized by high primary productivity, efficient water column filtration and sediment stability, have a pronounced capacity for carbon sequestration. This is enhanced by low decomposition rates in anaerobic seagrass sediments. The carbon captured by seagrass meadows contributes significantly to the total blue carbon. At a global scale, seagrass ecosystems are carbon sink hot spots and have profound influences on the global carbon cycle. This importance combined with the many other functions of seagrass meadows places them among the most valuable ecosystems in the world. Unfortunately, seagrasses are declining globally at an alarming rate owing to anthropogenic disturbances and climate change, making them also among the most threatened ecosystems on the Earth. The role of coastal systems in carbon sequestration has received far too little attention and thus there are still many uncertainties in evaluating carbon sequestration of global seagrass meadows accurately. To better assess the carbon sequestration of global seagrass ecosystems, a number of scientific issues should be considered with high priorities: 1) more accurate measurements of seagrass coverage at national and global levels; 2) more comprehensive research into species- and location-specific carbon sequestration efficiencies; 3) in-depth exploration of the effects of human disturbance and global climate change on carbon capture and storage by seagrass ecosystems.

[Assessment of marine environmental stress based on the integrated biomarker response index model: a case study in west coast of Guangxi].

Meretrix meretrix were collected for 3 times from 2011 to 2012, at 5 stations along west coast of Guangxi and wild and used as a biological indicator for assessing the marine environmental stress. Six biomarkers at individual, cellular and molecular levels were selected, including time required to drill the sand, phagocytic ability, stability of lysosomal membrane, ferric reducing ability of plasma (FRAP), acetylcholinesterase activity (AChE), and comet rate. Utilizing the Integrated Biological Response Index (IBR) model, the above biomarkers were integratedly analyzed and the data were displayed by intuitionistic star plots to evaluate the environmental situation of the 5 stations. The results indicated that the biological response indices (IBR/n) of the 5 stations varied between 2.30 and 8.68. Maowei Sea had the highest environmental stress, whereas Beilun Estuary had the lowest. Although different biomarkers were different in response to pollution stress, IBR model could effectively distinguish environmental stress of a specific area. The results of biomarker monitoring were basically in agreement with those of chemical monitoring.