posted on 2022-12-19, 15:38authored byC. Amaneesh, Shankari Anna Balan, P. S. Silpa, Ji Won Kim, Kozhumal Greeshma, A. Aswathi Mohan, Aiswarya Robert Antony, Hans-Peter Grossart, Hee-Sik Kim, Rishiram Ramanan
Plastic
debris is an established environmental menace
affecting
aquatic systems globally. Recently, microplastics (MP) and plastic
leachates (PL) have been detected in vital human organs, the vascular
system, and in vitro animal studies positing severe
health hazards. MP and PL have been found in every conceivable aquatic
ecosystemfrom open oceans and deep sea floors to supposedly
pristine glacier lakes and snow covered mountain catchment sites.
Many studies have documented the MP and PL impacts on a variety of
aquatic organisms, whereby some exclusively focus on aquatic microorganisms.
Yet, the specific MP and PL impacts on primary producers have not
been systematically analyzed. Therefore, this review focuses on the
threats posed by MP, PL, and associated chemicals on phytoplankton,
their comprehensive impacts at organismal, community, and ecosystem
scales, and their endogenous amelioration. Studies on MP- and PL-impacted
individual phytoplankton species reveal the production of reactive
oxygen species, lipid peroxidation, physical damage of thylakoids,
and other physiological and metabolic changes, followed by homo- and
heteroaggregations, ultimately eventuating in decreased photosynthesis
and primary productivity. Likewise, analyses of the microbial community
in the plastisphere show a radically different profile compared to
the surrounding planktonic diversity. The plastisphere also enriches
multidrug-resistant bacteria, cyanotoxins, and pollutants, accelerating
microbial succession, changing the microbiome, and thus, affecting
phytoplankton diversity and evolution. These impacts on cellular and
community scales manifest in changed ecosystem dynamics with widespread
bottom-up and top-down effects on aquatic biodiversity and food web
interactions. These adverse effectsthrough altered nutrient
cyclinghave “knock-on” impacts on biogeochemical
cycles and greenhouse gases. Consequently, these impacts affect provisioning
and regulating ecosystem services. Our citation network analyses (CNA)
further demonstrate dire effects of MP and PL on all trophic levels,
thereby unsettling ecosystem stability and services. CNA points to
several emerging nodes indicating combined toxicity of MP, PL, and
their associated hazards on phytoplankton. Taken together, our study
shows that ecotoxicity of plastic particles and their leachates have
placed primary producers and some aquatic ecosystems in peril.