Dynamics of an experimental microbial invasion.
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 reservoir-dominated 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.
Program in Ecology and Evolutionary Biology, Department of Biology, University of Oklahoma, Norman, OK 73019; Plankton Ecology and Limnology Laboratory, Department of Biology, University of Oklahoma, Norman, OK 73019;
Francisco
F
Acosta
Program in Ecology and Evolutionary Biology, Department of Biology, University of Oklahoma, Norman, OK 73019; Plankton Ecology and Limnology Laboratory, Department of Biology, University of Oklahoma, Norman, OK 73019;
Richard M
RM
Zamor
Advanced Center for Genome Technology, University of Oklahoma, Norman, OK 73019; Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73019.
Fares Z
FZ
Najar
Advanced Center for Genome Technology, University of Oklahoma, Norman, OK 73019; Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73019.
Bruce A
BA
Roe
Program in Ecology and Evolutionary Biology, Department of Biology, University of Oklahoma, Norman, OK 73019; Plankton Ecology and Limnology Laboratory, Department of Biology, University of Oklahoma, Norman, OK 73019; dhambright@ou.edu.
K David
KD
Hambright
D044822:Biodiversity; D002734:Chlorophyll / Q000737:chemistry; D057231:Climate Change; D004463:Ecology; D017753:Ecosystem; D005618:Fresh Water; D058087:Haptophyta / Q000502:physiology*; D058865:Introduced Species; D016014:Linear Models; D011157:Population Dynamics; D013997:Time Factors; D014871:Water Microbiology
D002734:Chlorophyll
Prymnesium; diversity; invasion resistance; microbial ecology; propagule pressure