The relationship between nitrate and phosphate nutrients in substrates with seagrass density: Implications for marine ecosystem sustainability

Introduction: Water conditions that greatly affect the density of seagrass species are the substrate fraction and nutrient content of the base substrate where the seagrass grows. This is important because seagrass utilizes dissolved nutrients in the waters and nutrients on the substrate for the production process. This study aims to determine the relationship between nitrate and phosphate nutrients on the substrate with seagrass density in Pajenekang Island, Liukang Tuppabiring District, Pangkep Regency, South Sulawesi. Methods: Data sampling of seagrass was carried out at north and west station using the line transect method where the data taken included seagrass frequency, cover, and density. Meanwhile, data collection of nitrate and phosphate nutrients on the substrate used a random sampling method and analysis with macro nutrien determination Morgan-Wolf extract. Findings: The results of study indicated that the seagrass density values in Pajenekang Island have various values, with the average seagrass density at the west station are 275 stands/m² and 356 stands/m² at the north station. The nutrient content on substrate in Pajenekang Island is low range when compared the result of other studies. Nitrate (0.36 ppm) and phosphate (0.49 ppm) at west station was significantly lower (P<0.05) compared to nitrate (0.49 ppm) and phosphate (0.64 ppm) at north station. The results of the Pearson correlation analysis among nitrate content and seagrass density on Pajenekang Island showed a negative relation with moderate correlation (-0.496*). Meanwhile, Pearson correlation analysis of phosphate content showed a negative relation by showing no relation (-0.166). This can be explained that there are other factors that effect on seagrass density in research location. Conclusion: It can be concluded that the seagrass density at Pajenekang Island varies. The average seagrass density at the western station is 275 individuals/m², while at the northern station, it is 356 individuals/m². Novelty/Originality of this article: The novelty of this research lies in analyzing the relationship between nitrate and phosphate nutrient content in the substrate and seagrass density on Pajenekang Island, which has not been widely studied in this region.

引言：影响海草物种密度的关键水环境因素为海草生长基底的基质组分与营养盐含量。这一点至关重要，因为海草可利用水体中的溶解态营养盐与基底中的营养盐完成自身的生理合成过程。本研究旨在探究南苏拉威西省庞卡普县柳康图帕比林区帕杰内康岛的基底硝酸盐与磷酸盐营养盐含量和海草密度之间的关联。
方法：海草数据采样采用样线法，在北部与西部站位开展，采集的海草数据包括出现频率、盖度与密度。与此同时，基底硝酸盐与磷酸盐营养盐的数据采集采用随机采样法，并通过Morgan-Wolf浸提法（Morgan-Wolf extract）进行大量营养盐测定分析。
结果：研究结果表明，帕杰内康岛的海草密度存在显著空间差异，西部站位的海草平均密度为275株/m²，北部站位则为356株/m²。与其他同类研究相比，帕杰内康岛基底的营养盐含量处于较低水平。西部站位的硝酸盐（0.36 ppm）与磷酸盐（0.49 ppm）含量显著低于北部站位的硝酸盐（0.49 ppm）与磷酸盐（0.64 ppm）含量（P<0.05）。对帕杰内康岛基底硝酸盐含量与海草密度的皮尔逊相关分析（Pearson correlation analysis）结果显示，二者呈显著负相关，相关程度为中等（-0.496*）。与此同时，磷酸盐含量与海草密度的皮尔逊相关分析结果显示二者呈负相关，但相关性极弱且无统计学意义（-0.166）。这表明研究区域内还存在其他影响海草密度的因素。
结论：综上可得出结论：帕杰内康岛的海草密度存在空间异质性，西部站位海草平均密度为275株/m²，北部站位则为356株/m²。
研究创新性：本研究的创新之处在于，针对帕杰内康岛基底硝酸盐与磷酸盐营养盐含量和海草密度的关联展开分析，该区域此前尚未开展过类似的广泛研究。