One of the most critical issues is ingestion of plastic debris, specifically microplastics. Many mesopelagic fish species migrate to the surface waters to feast on their main prey species, zooplankton and phytoplankton, which are mixed with microplastics in the surface waters. Additionally, research has shown that even zooplankton are consuming the microplastics themselves. Mesopelagic fish play a key role in energy dynamics, meaning they provide food to a number of predators including birds, larger fish and marine mammals. The concentration of these plastics has the potential to increase, so more economically important species could become contaminated as well. Concentration of plastic debris in mesopelagic populations can vary depending on geographic location and the concentration of marine debris located there. In 2018, approximately 73% of approximately 200 fish sampled in the North Atlantic had consumed plastic.