Effect of imbalanced nutrients and immigration on Prymnesium parvum community dominance and toxicity: results from in-lake microcosm experiments

Errera, Reagan M.; Roelke, Daniel L.; Kiesling, Richard L.; Brooks, Bryan W.; Grover, James P.; Schwierzke, Leslie; Ureña-Boeck, Fabiola; Baker, Jason W.; Pinckney, James L.

doi:10.3354/ame01199

Cited by 41 publications

(36 citation statements)

References 39 publications

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“…Most of these changes were in agreement with previous observations in P. parvum invasions, such as the reduction in abundances of diatoms, cercozoans, and chlorophytes (30,34,36,37) and the increased abundances of chrysophytes (37). We also observed a general increase in fungal OTU number, which has also been observed in P. parvum blooms in Lake Texoma (37).…”

Section: Discussionsupporting

confidence: 82%

“…Our results also are at odds with those of previous experiments that found that P. parvum abundances were correlated with nutrient concentrations, but not with additions of propagules (30). In that experiment, however, initial communities had differing background levels of P. parvum cells, and the number of introduced cells was low, equivalent to our low propagule pressure treatment, which, as shown here, did not exert enough propagule pressure to become established in the community.…”

Section: Discussioncontrasting

confidence: 57%

“…S1), possibly causing the observed dissociation between diversity and invasibility. However, previous experiments on P. parvum invasion processes showed that communities in large (1,570-L) enclosures and small (2-L) microcosms presented no significant differences in plankton dynamics for longer periods than those encompassed by our experiment (30). Furthermore, the difference between days was probably also caused by medium-term responses of the community to initial environmental changes because stabilization of communities in response to disturbances is a continuous process that can extend for longer periods than those covered by our incubation period (33).…”

Section: Discussioncontrasting

confidence: 44%

“…However, we observed a strong effect of propagule pressure in the community composition. The use of next generation sequencing allowed us to characterize the effects of this community response with greater precision and less bias than previous studies, which measured community composition using either microscope identification (34) or quantification of photosynthetic pigments (30,35). Both of these methods yield a skewed version of community composition, with a bias toward large, well-characterized taxa clustered into broad taxonomic categories (e.g., nanoflagellates).…”

Section: Discussionmentioning

confidence: 98%

“…However, there are several recent observational (27)(28)(29) and experimental field studies (30,31) examining the potential roles of immigration and nutrient availability in population dynamics and impacts of P. parvum. Although they provide good first steps in addressing the recent P. parvum range expansion, these earlier studies are limited in design.…”

mentioning

confidence: 99%

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Dynamics of an experimental microbial invasion

Acosta

Zamor

Najar

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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The ecological dynamics underlying species invasions have been a major focus of research in macroorganisms for the last five decades. However, we still know little about the processes behind invasion by unicellular organisms. To expand our knowledge of microbial invasions, we studied the roles of propagule pressure, nutrient supply, and biotic resistance in the invasion success of a freshwater invasive alga, Prymnesium parvum, using microcosms containing natural freshwater microbial assemblages. Microcosms were subjected to a factorial design with two levels of nutrient-induced diversity and three levels of propagule pressure, and incubated for 7 d, during which P. parvum densities and microbial community composition were tracked. Successful invasion occurred in microcosms receiving high propagule pressure whereas nutrients or community diversity played no role in invasion success. Invaded communities experienced distinctive changes in composition compared with communities where the invasion was unsuccessful. Successfully invaded microbial communities had an increased abundance of fungi and ciliates, and decreased abundances of diatoms and cercozoans. Many of these changes mirrored the microbial community changes detected during a natural P. parvum bloom in the source system. This role of propagule pressure is particularly relevant for P. parvum in the reservoirdominated southern United States because this species can form large, sustained blooms that can generate intense propagule pressures for downstream sites. Human impact and global climate change are currently causing widespread environmental changes in most southern US freshwater systems that may facilitate P. parvum establishment and, when coupled with strong propagule pressure, could put many more systems at risk for invasion. microbial ecology | diversity | invasion resistance | propagule pressure | Prymnesium

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Section: Discussionsupporting

confidence: 82%

Section: Discussioncontrasting

confidence: 57%

Section: Discussioncontrasting

confidence: 44%

Section: Discussionmentioning

confidence: 98%

mentioning

confidence: 99%

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Dynamics of an experimental microbial invasion

Acosta

Zamor

Najar

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Allelopathy and micropredation paradigms reconcile with system stoichiometry

2021

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Allelopathy, a type of interference competition involving exuded chemicals, has been documented for several types of organisms including terrestrial plants, aquatic macrophytes, microbes, and planktonic algae. However, due to the dynamic nature of the aquatic environment it is unclear whether allelopathy is an evolutionarily stable competition mechanism in such a setting. In this research, we consider a cosmopolitan harmful algae species, Prymnesium parvum, for which multiple ecological roles of its produced deleterious chemicals have been suggested, including broadcast allelopathy (chemicals produced and exuded) and micropredation via cell-cell interactions (chemicals produced and held within the cell). To further investigate the ecological role of the deleterious chemicals, bioassays (with phytoplankton and zooplankton target organisms) were conducted using various fractions of a P. parvum culture grown under balanced N:P stoichiometry or imbalanced, P-reduced stoichiometry. In addition, time-series counts were generated with cell density enumerations and observations of behavior of a mixed species culture at intervals over a 24-h period. Our results suggest that the apparent ecological role of the chemicals in a relatively high-density population shifts depending on system stoichiometry in regard to nitrogen and phosphorus. We show that under balanced N:P conditions, deleterious chemical production is low and cell contact mediates mortality of prey. Differently, under imbalanced, P-reduced conditions chemical effect is high and mass mortality occurs independent of cell contact. Thus, imbalanced N:P ratios shift the apparent ecological role of the deleterious chemicals from one of micropredation to one of broadcast allelopathy. These differences likely influence bloom dynamics and result in different ecological outcomes for systems affected by blooms. Further, we suggest that these differences indicate the importance of predatory mixotrophic feeding in the evolutionary maintenance of deleterious chemical production and the occurrence of allelopathic effects as a byproduct.

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