Heterotrophic picoplankton
Heterotrophic picoplankton is the fraction of plankton composed by cells between 0.2 and 2 μm that do not perform photosynthesis. They form an important component of many biogeochemical cycles.[1]
Cells can be either:
Archaea form a major part of the picoplankton in the Antarctic and are abundant in other regions of the ocean.[2] Archaea have also been found in freshwater picoplankton, but do not appear to be so abundant in these environments.[3]
Cell structure
[edit]Nucleic acid content in cells
[edit]Heterotrophic picoplankton can be divided into two broad categories: high nucleic acid (HNA) content cells and low nucleic acid (LNA) content cells.[4] Nucleic acids are large biomolecules that store and express genomic information. HNA picoplankton dominate in waters that are eutrophic to mesotrophic while low LNA picoplankton dominate in stratified oligotrophic environments.[5] The proportion of HNA picoplankton to LNA picoplankton is a defining characteristic of bacterioplankton communities.[6] Addition of glyphosate, a common herbicide that causes increased levels of phosphorus when introduced to aquatic systems, causes an increase in the ratio of HNA to LNA bacteria. Nucleic acids are a costly compound for cells to synthesize and the increased bioavailable phosphorus in the system likely allows HNA bacteria to rapidly synthesize more nucleic acids and divide.[4] HNA bacterioplankton are larger and more active than LNA picoplankton. HNA cells also have higher specific metabolic and growth rates, likely allowing these type of bacterioplankton to better utilize and exploit sudden increases in nutrients within the water column.[6] The relative abundance of HNA to LNA cells is related to overall system productivity, specifically chlorophyll concentration, though other factors likely also contribute to bacterioplankton distribution.[6]
Biogeochemical cycling
[edit]Dissolved organic matter
[edit]Heterotrophic picoplankton play a critical role in nutrient and carbon recycling in ecological food webs[4] by transforming and mineralizing organic matter.[7] Aquatic dissolved organic matter is one of the largest organic pools on Earth and a major part of the carbon cycle.[8] The majority of dissolved organic matter is either resistant to transformation or semi-labile, limiting the availability of these compounds to biodegradation.[9] Water bodies accumulate dissolved organic matter via both allochthonous sources, mainly decaying terrestrial plants and soil organic matter, and autochthonous sources, mainly from phytoplankton and macrophytes.[9] As major decomposers of organic matter, heterotrophic bacterioplankton act as an important link between detritus, dissolved organic matter, and higher trophic levels in aquatic systems.[1] Bacterioplankton degrade particulate organic matter into smaller compounds and either assimilate and absorb them or expel them as inorganic carbon.[10] Both of these processes promote transformation of matter within the aquatic system and promote energy flow and are important components of the overall quality of a water body.[8] Heterotrophic bacteria community structure and functionality is used to assess the trophic status and quality of freshwater systems.[8]
References
[edit]- ^ a b Sommaruga, Ruben; Robarts, Richard D (2006-01-17). "The significance of autotrophic and heterotrophic picoplankton in hypertrophic ecosystems". FEMS Microbiology Ecology. 24 (3): 187–200. doi:10.1111/j.1574-6941.1997.tb00436.x. ISSN 0168-6496.
- ^ Delong, E.F.; Wu, K.Y.; Prezelin, B.B.; Jovine, R.V.M. (1994). "High Abundance of Archaea in Antarctic Marine Picoplankton". Nature. 371 (6499): 695–697. Bibcode:1994Natur.371..695D. doi:10.1038/371695a0. PMID 7935813. S2CID 41491482.
- ^ Keough, B.P.; Schmidt, T.M.; Hicks, R.E. (2003). "Archaeal Nucleic Acids in Picoplankton from Great Lakes on Three Continents". Microbial Ecology. 46 (2): 238–248. doi:10.1007/s00248-003-1003-1. PMID 14708748. S2CID 2456459.
- ^ a b c Sabio y García, Carmen Alejandra; Schiaffino, María Romina; Lozano, Verónica Laura; Vera, María Solange; Ferraro, Marcela; Izaguirre, Irina; Pizarro, Haydée (2020-05-01). "New findings on the effect of glyphosate on autotrophic and heterotrophic picoplankton structure: A microcosm approach". Aquatic Toxicology. 222: 105463. doi:10.1016/j.aquatox.2020.105463. hdl:11336/168589. ISSN 0166-445X. PMID 32172181. S2CID 212730507.
- ^ Al-Otaibi, Najwa; Huete-Stauffer, Tamara M.; Calleja, Maria Ll; Irigoien, Xabier; Morán, Xosé Anxelu G. (2020-02-24). "Seasonal variability and vertical distribution of autotrophic and heterotrophic picoplankton in the Central Red Sea". Peer J. 8: e8612. doi:10.7717/peerj.8612. ISSN 2167-8359. PMC 7045887. PMID 32140305.
- ^ a b c Bouvier, Thierry; del Giorgio, Paul A.; Gasol, Josep M. (2007-08-17). "A comparative study of the cytometric characteristics of High and Low nucleic-acid bacterioplankton cells from different aquatic ecosystems". Environmental Microbiology. 9 (8): 2050–2066. doi:10.1111/j.1462-2920.2007.01321.x. ISSN 1462-2912. PMID 17635549.
- ^ Parvathi, A.; Zhong, X.; Pradeep Ram, A. S.; Jacquet, S. (2014-03-19). "Dynamics of auto- and heterotrophic picoplankton and associated viruses in Lake Geneva". Hydrology and Earth System Sciences. 18 (3): 1073–1087. Bibcode:2014HESS...18.1073P. doi:10.5194/hess-18-1073-2014. ISSN 1027-5606.
- ^ a b c Zhang, Wei; Zhou, Yongqiang; Jeppesen, Erik; Wang, Liqing; Tan, Hongxin; Zhang, Junyi (2019-08-20). "Linking heterotrophic bacterioplankton community composition to the optical dynamics of dissolved organic matter in a large eutrophic Chinese lake". Science of the Total Environment. 679: 136–147. Bibcode:2019ScTEn.679..136Z. doi:10.1016/j.scitotenv.2019.05.055. ISSN 0048-9697. PMID 31082588. S2CID 153311600.
- ^ a b Liu, Shasha; Hou, Junwen; Suo, Chengyu; Chen, Junyi; Liu, Xiaohui; Fu, Rui; Wu, Fengchang (2022-06-15). "Molecular-level composition of dissolved organic matter in distinct trophic states in Chinese lakes: Implications for eutrophic lake management and the global carbon cycle". Water Research. 217: 118438. Bibcode:2022WatRe.21718438L. doi:10.1016/j.watres.2022.118438. ISSN 0043-1354. PMID 35452972. S2CID 248074978.
- ^ Lønborg, Christian; Baltar, Federico; Calleja, Maria Ll.; Morán, Xosé Anxelu G. (17 November 2022). "Heterotrophic Bacteria Respond Differently to Increasing Temperature and Dissolved Organic Carbon Sources in Two Tropical Coastal Systems". Journal of Geophysical Research: Biogeosciences. 127 (12). Bibcode:2022JGRG..12706890L. doi:10.1029/2022JG006890. hdl:10754/686055. ISSN 2169-8953. S2CID 253665658.
