濒危海草贝克喜盐草生物量的时空变化及其关键影响因素

Spatiotemporal variation in biomass of threatened seagrass Halophila beccarii and its key influencing factors

关键词:  贝克喜盐草，生物量，间隙水理化因子，多元统计分析，华南沿海

Key words:  Halophila beccarii, biomass, porewater physicochemical factors, multivariate statistical analysis, South China coast

摘要:

为深入探究濒危海草贝克喜盐草(Halophila beccarii)生物量在华南沿海的分布特征及其驱动因素，该研究以华南沿海4省(区)6个区域(花场湾、洋浦、沙井、唐家湾、义丰溪和诏安)的贝克喜盐草为研究对象，系统分析了其生物量在华南沿海的时空动态变化及关键环境影响因子。结果表明：（1）华南沿海贝克喜盐草的平均地上生物量、地下生物量和总生物量分别为(11.98±13.06) g·m-2 DW (平均值±标准差SD，以下同)、(12.06±12.96) g·m-2 DW和(24.05±23.70) g·m-2 DW。其中，唐家湾的生物量显著低于其他研究地点(P<0.05)。生物量呈现明显的季节变化，冬春季低、夏秋季高。（2）除pH和亚硝酸盐浓度外，其他环境因子(如水温、盐度、无机磷、硝酸盐和氨氮)在不同研究地点间均存在显著性差异(P<0.05)。（3）相关性分析结果显示，地上生物量与水温和无机磷浓度呈显著正相关(P<0.05)、而与氨氮浓度呈显著负相关(P<0.05)；地下生物量与无机磷和硝酸盐浓度呈显著正相关(P<0.05)；总生物量与无机磷和硝酸盐浓度呈显著正相关(P<0.05)，但与氨氮浓度呈显著负相关(P<0.05)。（4）主成分分析(PCA)结果显示，水温和亚硝酸盐是促进总生物量积累的主要正向因子，而氨氮对其产生抑制作用。（5）线性回归进一步证实，间隙水理化因子对总生物量的影响具有显著线性关系(R2=0.118, P<0.001)。该研究结果对深入理解贝克喜盐草的生态习性、环境适应机制及其濒危原因具有重要的科学价值，同时为该物种的保护与管理提供了理论依据。

Abstract:

To enhance the understanding of biomass distribution and its driving factors in the threatened seagrass?Halophila beccarii?(Asch.) along the South China coast, this study systematically investigated the spatiotemporal dynamics of its biomass and key environmental variables across six regions—Huachangwan, Yangpu, Shajing, Tangjiawan, Yifengxi, and Zhao'an—located in four coastal provinces of southern China. Seasonal field sampling was conducted to capture intra-annual variations. Key findings include: (1) The mean aboveground, belowground, and total biomass values of?H. beccarii?were (11.98 ± 13.06) g·m-2 DW, (12.06 ± 12.96) g·m?2 DW, and (24.05 ± 23.70) g·m?2 DW (mean ± SD), respectively. Biomass at Tangjiawan was significantly lower than that at other sites (P < 0.05). Distinct seasonal patterns were observed, with lower biomass during winter and spring and higher values in summer and autumn. (2) Except for pH and nitrite, all other environmental factors—water temperature, salinity, inorganic phosphorus, nitrate, and ammonia nitrogen—differed significantly among sites (P < 0.05) , indicating substantial spatial heterogeneity in habitat conditions.?(3) Correlation analyses revealed that aboveground biomass was significantly positively correlated with water temperature and inorganic phosphorus (P < 0.05), and negatively correlated with ammonia nitrogen (P < 0.05). Belowground biomass was positively correlated with inorganic phosphorus and nitrate (P < 0.05). Total biomass showed positive correlations with inorganic phosphorus and nitrate (P < 0.05), and a negative correlation with ammonia nitrogen (P < 0.05), suggesting that both nutrient availability and temperature play key roles in regulating productivity. (4) Principal component analysis identified water temperature and nitrite as the main positive factors affecting total biomass, whereas ammonia nitrogen exhibited an inhibitory effect, underscoring the importance of nutrient balance and thermal environment. (5) Linear regression confirmed a significant albeit modest relationship (R2 = 0.118, P < 0.001) between porewater physicochemical factors and total biomass, indicating that other unmeasured variables may also influence biomass variability. This study improves our insight into the ecological characteristics, environmental adaptations, and causes of endangerment of?H. beccarii, and offers a scientific foundation for its conservation and management amid growing anthropogenic pressures and climate change.