Dissertation Research:Shifting Baselines? The ecological implications of simultaneous eutrophications and overfishing

将基线?富营养化和过度捕捞同时产生的生态影响过度捕捞和人为营养物污染是全球沿海环境面临的最紧迫问题之一。这两种压力源都会影响藻类和海草的生长限制营养物质（氮和磷）的供应，而藻类和海草是大多数海洋生态系统的基础。人类的投入增加了营养物质的供应，这些营养物质主要来自污水，而过度捕捞已被证明会减少营养物质的供应，因为鱼类通过排泄提供了大量的营养物质。这些截然不同的输入提出了一个悖论，即人类来源的营养素可能取代鱼类来源的营养素。然而，人类来源的营养物比鱼类来源的营养物磷含量高，这可能会改变营养物供应的基线，进而改变藻类和海草物种的多样性和生长速度。过度捕捞和营养物富集将在巴哈马群岛的试验性斑礁生态系统上独立和同时模拟。将确定对藻类和海草物种多样性、生长和营养限制变化的影响。实验珊瑚礁系统将被用作实地考察地点，实验结果将用于向当地高中生推广工作。亚热带和热带海洋生态系统已经进化到在极低的营养条件下发挥作用，使它们特别容易受到营养动态的微小变化的影响。这些生态系统提供的巨大服务似乎严重依赖于氮和磷的数量和相对供应，但对同时过度捕捞和富营养化对这些服务的影响缺乏了解，特别是在加勒比地区。增进对营养影响的了解对全球海洋生态系统的管理和保护至关重要。

Shifting Baselines? The ecological implications of simultaneous eutrophication and overfishingOverfishing and human-derived nutrient pollution are among the most pressing issues facing coastal environments globally. Both these stressors affect the supply of growth-limiting nutrients (nitrogen (N) and phosphorus (P)) for algae and seagrasses, the base of most marine ecosystems. Human inputs increase the supply of nutrients, which are largely sewage-derived, while overfishing has been shown to reduce nutrient supply because fish provide substantial inputs of nutrients via excretion. These contrasting inputs present the paradox that human-derived nutrients may supplant fish-derived nutrients. However, human-derived nutrients are high in P relative to fish-derived nutrients, which may be altering the baseline at which nutrients are supplied and in turn changing the diversity and growth rates of algae and seagrass species. Overfishing and nutrient enrichment will be simulated independently and simultaneously on experimental patch-reef ecosystems in the Bahamas. The implications for changes in diversity, growth and nutrient limitation of algae and seagrass species will be determined . The experimental reef system will be used as a field trip site and experimental results will be used in outreach efforts to local high school students. Subtropical and tropical marine ecosystems have evolved to function under extremely low nutrient conditions, making them particularly susceptible to even minor alterations in nutrient dynamics. The enormous services provided by these ecosystems appear to critically hinge on the amount and relative supply of N and P, yet understanding of the effects of simultaneous overfishing and eutrophication for these services is lacking, particularly in the Caribbean. Increased understanding of nutrient effects is critical to the management and conservation of marine ecosystems globally.