关键词: 高温胁迫, 海草资源, 光合作用, 碳氮代谢, 适应机制

Abstract: Seagrass exhibits high levels of primary productivity in nearshore waters, and its growth is regulated by temperature. Under the background of global climate change, temperature stress has emerged as a significant factor affecting seagrass growth. Adaptation to global warming determines whether seagrass can fulfill its ecological services. We summarized the response and adaptation mechanisms of seagrass to global warming from the aspects of the physiological metabolism, distribution pattern, and gene expression. It was found that increasing temperatures changed the carbohydrate content in seagrass and inhibited its ability to absorb and assimilate nitrogen. This subsequently led to a reduction in the total nitrogen content and the metabolites related to nitrogen cycling in seagrass, and ultimately threatening its survival. Moreover, increasing temperature also inhibited the PSII activity of the photosynthetic system. The average threshold of temperature for photosynthesis in temperate and tropical seagrass is 22.3 and 29.8 ℃, respectively. Warming also led to a decrease in the growth rate and biomass of seagrass. Temperate and tropical seagrass gradually migrated to higher latitudes under the warming scenarios. In response to the stress of warming, seagrass can maintain the important functions of the ecosystems by increasing heat dissipation, accumulating saturated fatty acids, and increasing the activity of antioxidant enzymes and the expression of heat shock proteins (HSP70, HSP90). Finally, we proposed future research priorities: (1) clarifying the effects of increased temperature on the pattern of carbon partitioning in seagrass; (2) identifying the molecular mechanism of seagrass photosynthesis in response to high temperature stress; (3) investigating the effects of global warming on the distribution of tropical seagrass; and (4) exploring the mechanisms of high temperature stress on antioxidant enzyme activity and gene expression. These studies are essential to fully understand the survival potential of seagrass under global climate change and provide a scientific basis for the protection of seagrass ecosystems.

Key words: heat stress, seagrass resource, photosynthesis, carbon and nitrogen metabolism, adaptation mechanism