Macroalgal blooms are increasing on the Belize Barrier Reef (BBR) as scleractinian coral cover declines. Although some have attributed this to reduced grazing, the role of land-based nutrient pollution has not been assessed. Nutrient enrichment was quantified through macroalgal tissue analysis from Belize City to the offshore fore reef and at several central BBR lagoon sites. These recent data were compared to baseline data from the 1980s. Significant nearshore-to-offshore gradients of %N, %P and δ¹³C in macroalgae all indicated land-based sources of these nutrients. Macroalgal δ¹⁵N values were generally enriched in nearshore waters where values matched those reported for human sewage. Notably, the N:P ratios of recent macroalgae measurements were elevated at all sites, more than two-fold higher than values from the 1980s (~30: 1 to 70:1). These results support the hypothesis that nitrogen enrichment from land-based sources has increased phosphorus limitation driving macroalgal blooms and coral stress on the BBR.

随着 scleractinian 珊瑚覆盖率下降，伯利兹堡礁 (BBR) 上的大型藻华正在增加。尽管有些人将此归因于放牧减少，但尚未评估陆基养分污染的作用。通过从伯利兹市到近海前礁和几个中央 BBR 泻湖地点的大型藻类组织分析，对营养物质的富集进行了量化。这些最近的数据与 1980 年代的基线数据进行了比较。大型藻类中 %N、%P 和 δ ¹³ C 的近岸到近海的显着梯度都表明这些养分的陆源来源。巨藻δ ¹⁵N 值通常在近岸水域富集，其值与人类污水报告的值相匹配。值得注意的是，最近所有地点的大型藻类测量的 N:P 比率都提高了，比 1980 年代的值（~30:1 到 70:1）高两倍以上。这些结果支持了以下假设：陆地来源的氮富集增加了磷限制，从而推动了 BBR 上的大型藻类大量繁殖和珊瑚压力。