Anthropogenic impacts on community structure and function within intertidal ecosystems

生态系统功能与群落结构的关系是复杂的、动态的。理解这种复杂的相互作用背后的机制，以及这种关系在我们改变环境时如何变化，是一个具有挑战性的问题。这一挑战现在尤其重要，因为气候变化和污染等人为活动正在迅速改变水生和陆地群落，从而改变营养物质和元素在这些系统中的循环方式。维护生态系统是一项要求，因为作为一个社会，我们依赖这些系统来获得健康的土壤、清洁的空气和水。 2004年，“微塑料”一词被引入，用来描述一种新发现的污染物；小于5毫米的微塑料(例如化妆品擦洗中的微珠)和起源于较大塑料物品(例如瓶子)降解的微塑料。呈指数级增长的文献表明，这些污染物对海洋生态系统和那些物种构成威胁，包括依赖这些生态系统提供服务和商品的人类。 关于微塑料可能对水生生态系统产生的影响，仍然有更多的问题而不是答案。数据差距包括沉积物中微塑料吸收金属的能力方面的“地球化学”行为，沉积物中与微塑料相关的金属的生物可利用性，以及这些金属通过海洋食物网转移到包括人类在内的更高营养水平的可能性。 传统上，沉积物被描述为有机质的百分比以及锰和铁的氧化物。这三个组分是影响沉积物过程的关键因素，例如金属对吸收沉积物的生物体的生物有效性。由于沉积物中微塑料的浓度很高(最高可达8000微塑料kg-1)，而且这些颗粒有可能影响地球化学过程，因此必须认为沉积物不仅包含经典的地球化学参数，而且现在还包含微塑料。微塑料有可能成为镉等有毒金属的第四个吸附场所，因为它比其他三种沉淀物成分更具竞争力，从而提供了迄今尚未量化的金属进入食物网的机会。微塑料对金属的吸附也可能取决于沉积物基质(例如，与有机物含量较低的沉积物相比，高有机质沉积物对金属的吸附较少)和微塑料的类型(例如，微珠与纤维)。我的5年研究计划的目标是解决这些关键数据差距，并确定微塑料在通过潮间带食物网转移有毒金属方面的作用。然后，这一新信息可用于评估沉积物中微塑料存在的最大风险的沿海生态系统在海洋食物网内污染物转移中的作用。

The relationship between ecosystem function and community structure is complex and dynamic. Understanding the mechanisms underlying this complex interplay and how this relationship changes as we modify our environment is a challenging problem. This challenge is especially relevant now as anthropogenic activities such as climate change and pollution are rapidly altering aquatic and terrestrial communities and hence how nutrients and elements cycle through these systems. The maintenance of ecosystems is a requirement because as a society we are dependent on these systems for healthy soils, clean air and water. In 2004, the term “microplastics” was introduced to describe a newly recognized pollutant; microplastics less than 5 mm (e.g., microbeads in cosmetic scrubs) and microplastics whose origin is the degradation of larger plastic items (e.g., bottles). An exponentially growing body of literature has demonstrated the threat these pollutants pose to marine ecosystems and those species, including humans that rely on these ecosystems for their services and goods. There are still more questions than answers as to the impact microplastics may have on aquatic ecosystems. Data gaps include the “geochemical” behavior of microplastics within sediments with respect to their ability to sorb metals, the bioavailability of metals associated with microplastics within sediments, and the potential for these metals to move through marine foodwebs to higher trophic levels including humans. Traditionally, sediments have been described as percent organic matter and oxides of manganese and iron. These three components are key factors influencing sediment processes such as metal bioavailability to sediment-ingesting organisms. With the high concentrations of microplastics that occur within sediments (up to 8000 microplastics kg-1 sediment) and the potential for these particulates to influence geochemical processes, sediments must be viewed as being comprised not only of the classic geochemical parameters, but now, also microplastics. Microplastics have the potential to act as a 4th sorption site for toxic metals such as cadmium by outcompeting the other three sediment components providing an as yet quantified entry of metals into foodwebs. Metal sorption by microplastics could also be dependent on the sediment matrix (e.g., sediments high in organic matter would result in less sorption of metals by microplastics versus sediments low in organic matter) and the type of microplastic (e.g., microbead versus fiber). The objective of my 5 year research plan is to address these key data gaps and determine the role of microplastics in the transfer of toxic metals through intertidal foodwebs. This new information can then be applied to evaluate coastal ecosystems at greatest risk to the presence of microplastics within sediments with respect to their role in the transfer of pollutants within marine food webs.