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The role of persistent organic pollutants in cyanobacterial bloom proliferation

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The user has requested enhancement of the downloaded file. Ted Harris Student Corner The role of persistent organic pollutants in cyanobacterial bloom proliferation

yanobacteria are a main component Persistent organic pollutants phytoplankton community composition. of the phytoplankton community For more than 60 years, a mixture of Harris and Smith (2016) assessed how Cin aquatic ecosystems. Although over 400 different herbicides, pesticides, phytoplankton community composition cyanobacteria look and function like algae and fungicides, along with a myriad of is effected by POPs by investigating if to the naked eye, they are technically other unaccounted-for pharmaceuticals, the current scientific literature indicated bacteria that can perform photosynthesis. personal care products, and industrial that cyanobacteria were favored relative Because cyanobacteria function like chemicals have unintentionally found to other phytoplankton taxa in the algae, they require nutrients and light to their way into oceans, estuaries, rivers, presence of environmentally relevant POP grow and reproduce, and thus compete streams, lakes, and reservoirs (Stone et al. concentrations. with true algae for these growth-limiting 2014). These chemical compounds, which resources. can exist in liquid, solid, or gas forms, Methods Cyanobacteria produce a wide range are broadly termed persistent organic Google Scholar and Web of Science of chemical compounds to compete with pollutants due to their ability to persist were searched for studies that explicitly algae for growth-limiting resources. in the environment. Some degrade in a compared cyanobacteria to other These include taste-and-odor compounds matter of days, while others take months, phytoplankton taxa from 1980-2015. A that degrade raw drinking water supplies years, or decades to fully degrade. POPs total of 107 publications, which included and potent toxins that have caused the can be transported thousands of miles 217 experiments on various POPs, were death of fish, birds, livestock, and in rare from their sources by migrating animals, found to compare cyanobacteria to cases even humans. Large blooms of flowing waters, and atmospheric wind their photosynthetic counterparts in the cyanobacteria can pose a health hazard currents, and have contaminated even presence of POPs. The 217 experiments to animals and humans, impair drinking relatively pristine environments like the examined 133 distinctly different POPs, and irrigation water supplies, and cause Arctic. As a result, POPs frequently co- which included herbicides, pesticides, billions of dollars of economic damage occur and are detectable throughout the fungicides, pharmaceutical and personal (Paerl and Otten, 2013). world’s surface waters. care products, and industrial chemicals. A Unfortunately, increases in the POPs can have devastating effects majority of these studies were conducted frequency and intensity of cyanobacterial on non-target organisms. For example, in the laboratory, or in small-scale outdoor blooms are being noted worldwide studies have linked POP exposure to experimental enclosures. (Taranu et al. 2015). Until recently, an increased risk of prostate and breast Frequency histograms were used to cyanobacterial blooms were primarily cancer, non-Hodgkin lymphoma, present results. The histograms grouped observed in nutrient-rich eutrophic leukemia, and multiple myeloma in the 217 experiments into three distinct and hypereutrophic systems, and were humans (Alavanja et al. 2013). POP categories; positive, neutral, and negative relatively rare in less nutrient-rich, exposure also causes adverse effects (Figure 1). A denotation of positive oligotrophic to mesotrophic waters. to aquatic organisms, including death indicates that in the presence of a POP Alarmingly, however, cyanobacterial (Stone et al. 2014). Thus, while POPs cyanobacteria was favored over all over blooms have recently been measured in may be effective at eliminating their phytoplankton taxa tested within a single oligotrophic to mesotrophic lakes (Taranu targeted organisms or be extremely experiment. A neutral POP response et al. 2015). Although the causes for useful as industrial chemicals, non- was given if cyanobacteria had an these potential changes are not yet fully targeted organisms can be affected by the intermediary response relative to other understood, the manuscript by Harris and unintentional release of POPs to aquatic phytoplankton taxa. A negative POP Smith (2016) indicates that the loading ecosystems. response indicated that cyanobacteria of persistent organic pollutants (POPs) Although substantial scientific were depressed compared to other to aquatic systems may be an under- research has been conducted on the phytoplankton taxa tested in a single recognized contributor to cyanobacterial non-target effects of POPs on specific experiment. In some cases, multiple proliferation in the world’s surface waters. individual aquatic organisms, less experiments investigated a single unique is known about effects of POPs on POP (e.g., the active ingredient in the

26 Spring 2016 / NALMS • LAKELINE phytoplankton taxa. Thus, the presence 3 showed a negative result. No broad of most herbicides seemed to favor conclusion can be made based on so few cyanobacteria species compared to true studies, and additional research is needed algae. to unravel the complex relationship that Harris and Smith (2016) showed exists between phytoplankton community other classes of POPs favored composition and industrial POPs. Student Corner cyanobacteria over true algae. Unlike In total, 42 percent of the surveyed herbicides, the other classes of POPs do studies found that cyanobacteria were not specifically target photosynthetic favored over true algae in the presence organisms. For example, pesticides and of POPs (Figure 1). Given that only 28 fungicides target non-photosynthetic percent of the total experiments showed organisms. Yet, of the 46 pesticide other phytoplankton dominated in the and fungicide experiments surveyed presence of POPs, Harris and Smith 87 percent showed either a positive (2016) hypothesized that at a given or neutral response of cyanobacteria nutrient load aquatic systems with compared to other phytoplankton taxa, relatively high POP loading will likely indicating non-target compounds may have a higher proportion of cyanobacteria favor cyanobacteria more than other in their phytoplankton communities Figure 1. Histograms showing the effects phytoplankton community members. compared to systems with low POP of Persistent Organic Pollutants (POPs) Experiments surveyed using loading (Figure 2). Therefore, lakes on cyanobacteria. The positive (green), pharmaceutical and personal care and reservoirs with relatively high POP neutral (brown), and negative (blue) products had two distinct responses. 27 loading will likely be more “blue-green” categories refer to POPs that favored experiments showed a positive result, than systems with relatively low POP cyanobacteria, showed taxa more and less sensitive than cyanobacteria, and did not while 36 showed a negative result when loading (Figure 3). Because nutrient favor cyanobacteria, respectively, in multi- cyanobacteria were compared to other enrichment, warmer temperatures, and phytoplankton species studies that examined phytoplankton taxa in the presence of selective pressures from POPs already more than one phytoplankton taxa group. pharmaceutical and personal care product seem to be creating some of the world’s Numbers above histogram bars represent the POPs. This strong distinction between largest cyanobacterial blooms to date, number of POPs in each category. Figure pharmaceutical and personal care product increased loading of nutrients and POPs, modified from Harris and Smith (2016). experiments was due to experiments that coupled with warmer surface water tested antibiotics. Because cyanobacteria temperatures are only likely to worsen are technically bacteria, studies that large-scale cyanobacterial proliferation in herbicide RoundUpTM – glyphosate); each experimented with antibiotics generally years to come. individual experimental response was showed that counted in only one of the three distinct cyanobacteria were categories. Further methodological details not favored in their can be found in Harris and Smith (2016). presence. However, more recent studies Results and Discussion (e.g., Liu et al. Several trends were evident in 2012) have found the current literature. A distinct trend that cyanobacteria was especially evident in herbicides; are favored in the POPs that are specifically designed to presence of some eliminate photosynthetic organisms. antibiotics, which Of the 99 herbicide experiments that may indicate that directly compared cyanobacteria to other cyanobacteria are algae, nearly half (46 percent) showed becoming more cyanobacteria were favored over true tolerant to antibiotics. algae in the presence of herbicide POPs. Few experimental Alarmingly, of the studies involving results investigated glyphosate, the active ingredient in the how cyanobacteria most widely used herbicide in the world, faired compared all seemed to favor cyanobacteria. Indeed, to other algae in of the 13 glyphosate based experiments, the presence of Figure 2. Hypothesized relationships between percent (%) 8 showed to favor cyanobacteria over all industrially generated cyanobacterial biomass in the phytoplankton community and water column concentrations of total phosphorus, under contrasting high other phytoplankton taxa tested while POPs. Of the 7 and low loadings of cyanobacteria-promoting Persistent Organic studies, 4 showed a 5 showed that cyanobacteria had an Pollutants (POPs); the low POP line will reach its asymptote to the intermediary response relative to other positive result and right of the shown graph.

Spring 2016 / NALMS • LAKELINE 27 Figure 3. Contrasting responses of aquatic ecosystems that receive high and low Persistent Organic Pollutant (POP) loading. The presence of cyanobacteria-promoting POPs is hypothesized to increase the proportion of cyanobacteria at any given level of nutrient loading. These key POPs may include biocides; pharmaceutical and personal care products; and industrial chemicals.

References Taranu, Z.E., I. Gregory-Eaves, P.R. on finding applied management strategies to Alavanja, M.C.R., M.K. Ross and M.R. Leavitt, L. Bunting, T. Buchaca, J. cyanobacteria blooms through the manipulation Bonner. 2013. Increased cancer burden Catalan, I. Domaizon, P. Guilizzoni, A. of nutrient ratios. He has been a member of among pesticide applicators and others Lami, S. McGowan, H. Moorhouse, G. NALMS since 2010 and just completed a term as due to pesticide exposure. CA Cancer J Morabito, F.R. Pick, M.A. Stevenson, the Student At-Large Director. c Clin, 63: 120-142. P.L. Thompson and R.D. Vinebrooke. Harris, T.D. and V.H. Smith. 2016. Do 2015. Acceleration of cyanobacterial persistent organic pollutants stimulate dominance in north temperate-subarctic cyanobacterial blooms? Inland Waters, lakes during the Anthropocene. Ecol 6: 124-130. Lett, 18: 375-384. Liu, Y., B. Gao, Q. Yue, Y. Guan, Y. Wang and L. Huang. 2012. Influences of two antibiotic contaminants on the Ted Harris is a Ph.D. production, release and toxicity of student at the University microcystins. Ecotoxicol Environ Saf, of Kansas, advised by 77, 79-87. Jennifer Graham (USGS) Paerl, H.W. and T.G. Otten. 2013. and Val Smith. Ted’s Harmful cyanobacterial blooms: causes, current research focuses consequences, and controls. Microb on environmental and Ecol, 65: 995-1010. anthropogenic factors Stone, W.W., R.J. Gilliom and K.R. that favor toxic and Ryberg. 2014. Pesticides in U.S. taste-and-odor causing cyanobacterial blooms. streams and rivers: occurrence and Ted has bachelor’s degrees from the University trends during 1992-2011. Environ Sci of Missouri and a master’s degree from the Technol, 48: 11025-11030. University of Idaho. Ted’s master’s degree focused

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