Anthropogenic nutrients mitigate importance of fish-mediated nutrient supply for seagrass beds in Haiti
Anthropogenic nutrients mitigate importance of fish-mediated nutrient supply for seagrass beds in Haiti
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人为营养物质降低了海地海草床鱼类介导的营养供应的重要性
作者：
Emily M. Brines;Mona A Andskog;Katrina S. Munsterman;C. Layman;Matthew McCoy;Jacob E. Allgeier
从消费废物中提供营养，即，消费者介导的营养动态对海洋环境，特别是贫营养系统的初级生产至关重要。然而，人类的影响可以通过两种主要方式影响消费者介导的营养素的影响：（1）过度捕捞可以减少消费者人口，从而减少他们提供的营养素，（2）人为营养素富集可以改变营养素限制的基线。以前的工作表明，人工鱼礁创造了生物地球化学热点，可以测量周围初级生产者的营养反应。我们在海地Ile-a-Vache附近的浅水海草床中用88个煤渣块建造了8个人工礁，以测试鱼类介导的营养物质和人为营养物质对人工礁周围优势海草海龟生长率的相互作用影响。我们发现：（1）人为营养盐富集似乎是影响人工礁附近海草生长的主要因素，（2）尽管总体上人为营养盐富集效应，但消费者介导的营养盐仍会产生生物地球化学热点，这两种营养盐来源对海草生长速率产生叠加影响。我们还发现，氮和磷类似地预测海草生长速率，并且比它们的比率更好，这表明氮和磷的供应速率都限制海草生产。从这项研究的结果表明，人为营养物质的影响可以强烈影响海草生长在这些系统中，但消费者可以提供的营养源，海草生长具有添加剂的影响。
The supply of nutrients from consumer waste products, i.e., consumer-mediated nutrient dynamics, is critical for primary production in marine environments, especially in oligotrophic systems. However, human impacts can influence the effects of consumer-mediated nutrients in two main ways: (1) overfishing can reduce consumer populations and thus the nutrients they supply, (2) anthropogenic nutrient enrichment can shift baselines of nutrient limitation. Previous work has shown that artificial reefs create biogeochemical hot spots from which nutrient responses by surrounding primary producers can be measured. We constructed eight artificial reefs from 88 cinder blocks in shallow seagrass beds near Ile-a-Vache, Haiti, to test for interacting effects of fish-mediated nutrients and anthropogenic nutrients on growth rates of the dominant seagrass, Thalassia testudinum, surrounding the artificial reefs. We found that (1) anthropogenic nutrient enrichment appears to be the primary factor influencing seagrass growth close to the artificial reef, and (2) despite overall anthropogenic nutrient enrichment effects, consumer-mediated nutrients still generate biogeochemical hot spots and the two nutrient sources additively influence seagrass growth rates. We also found that nitrogen and phosphorus similarly predict seagrass growth rates, and better so than their ratio, indicating the supply rates of nitrogen and phosphorus are both limiting seagrass production. Results from this study indicate that the effect of anthropogenic nutrients can strongly influence seagrass growth in these systems, but consumers can supply a source of nutrients that has additive effects on seagrass growth.