Impact of pollution on phytoplankton and implications for marine econiches

Abstract

Pollution in marine environments has been widely studied because of its impact, both direct and indirect, on human livelihood. Pollution may arise from different sources, the most well known being influx of domestic sewage, industrial waste and mining effluents. Shipping activities also contribute to pollution, either through accidental oil spills, ballasting and deballasting activities or bioinvasion. Pollution due to microplastics, radiation and heat (thermal pollution) is also gaining prominence. The impact of these varying sources of pollution on marine econiches is wide ranging; different trophic levels are affected. A pivotal trophic level impacted by pollution in the marine environment is phytoplankton, known for their role as microscopic primary producers and base of aquatic food webs. Pollution affects phytoplankton communities at different levels - abundance, growth strategies, dominance and succession patterns. Even if no direct changes in phytoplankton communities are visible, pollutants may accumulate in phytoplankton and be passed on to other trophic levels in a cascading manner, resulting in biomagnification of certain pollutants. This article focusses on the effects of different types of pollution (both point sources and non-point sources) on phytoplankton communities. The anthropocentric concept of ‘pollution’ and the links between pollution, eutrophication and harmful algal blooms (HABs) are also analyzed. An understanding of the synergistic interactions between these aspects and climate change effects will be useful to devise suitable remediation strategies for future use.