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Song XY, Liu HX, Zhong Y, Tan YH, Qin G, Li KZ, Shen PP, Huang LM, Wang YS. Bacterial growth efficiency in a partly eutrophicated bay of South China Sea: Implication for anthropogenic impacts and potential hypoxia events. ECOTOXICOLOGY (LONDON, ENGLAND) 2015; 24:1529-1539. [PMID: 26024618 DOI: 10.1007/s10646-015-1497-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/20/2015] [Indexed: 06/04/2023]
Abstract
Bacterial metabolism plays a dual role [bacterial production (BP) and bacterial respiration (BR)] in the aquatic ecosystem and potentially leads to hypoxia in the coastal eutrophic area. Bacterial growth efficiency (BGE) is an important index showing the contribution of bacterial metabolism to marine biological production and carbon budget in the pelagic ecosystem. In this study, the spatial and seasonal variety as well as diurnal variation dynamics of BGE and associated ecological characteristics were investigated in a partly eutrophicated subtropical bay (the Daya Bay) located in the northern South China Sea. Furthermore, the relationship between bacterial metabolism and potential hypoxia event was analyzed. The average BGE was 0.14 and 0.22 in summer and winter, respectively, which was lower than the mean value ever reported in other coastal and estuarine waters. The diurnal variations of BGE and BP were widely fluctuated in the Daya Bay, with approximately 3-8 fold variation of BP and 2-3 fold variation of BR in different seasons, suggesting the importance of short-term ecological dynamics on evaluating the long-term ecological processes in the coastal waters. BR was the predominant contributor to the bacterial carbon demand; however, the variation of BGE was controlled by BP in both seasons. BGE was always high in the near-shore waters with higher eutrophic level and more active BP and BR. The bacterial metabolism could deplete dissolved oxygen (DO) in the Daya bay within about 9 days when the water body was enclosed and photosynthesis was prohibited. Therefore, low DO concentration and potential hypoxia was more likely to be found in the near-shore waters of the Daya Bay in summer, since the water was stratified and enclosed with poor water exchange capacity in this area. While in winter, hypoxia seldom occurred due to vertical mixing throughout the water column. Further biological-physical coupling research is recommended to find out the detailed formation mechanism of hypoxia in the bay, and to predict the potential hypoxia events and their environmental impacts in the future.
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Affiliation(s)
- Xing-Yu Song
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China.
- Daya Bay Marine Biology Research Station, Chinese Academy of Science, Shenzhen, 518121, China.
| | - Hua-Xue Liu
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China
- South China Sea Fisheries Research Institute, Chinese Academy of Fisheries Sciences, Guangzhou, 510300, China
| | - Yu Zhong
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China
- Daya Bay Marine Biology Research Station, Chinese Academy of Science, Shenzhen, 518121, China
| | - Ye-Hui Tan
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China
| | - Geng Qin
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China
| | - Kai-Zhi Li
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China
| | - Ping-Ping Shen
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China
| | - Liang-Min Huang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China
| | - You-Shao Wang
- State Key Laboratory of Tropical Oceanology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China
- Daya Bay Marine Biology Research Station, Chinese Academy of Science, Shenzhen, 518121, China
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Abstract
Despite the impressive advances that have been made in assessing the diversity of marine microorganisms, the mechanisms that underlie the participation of microorganisms in marine food webs and biogeochemical cycles are poorly understood. Here, we stress the need to examine the biochemical interactions of microorganisms with ocean systems at the nanometre to millimetre scale--a scale that is relevant to microbial activities. The local impact of microorganisms on biogeochemical cycles must then be scaled up to make useful predictions of how marine ecosystems in the whole ocean might respond to global change. This approach to microbial oceanography is not only helpful, but is in fact indispensable.
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Affiliation(s)
- Farooq Azam
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093, USA.
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Farjalla VF, Enrich-Prast A, Esteves FA, Cimbleris ACP. Bacterial growth and DOC consumption in a tropical coastal lagoon. BRAZ J BIOL 2006; 66:383-92. [PMID: 16862291 DOI: 10.1590/s1519-69842006000300002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2003] [Accepted: 06/14/2004] [Indexed: 11/21/2022] Open
Abstract
The aims of this research were to determine the main limiting nutrient to bacterial growth in Imboassica lagoon, southeastern Brazil, to estimate the percentage of dissolved organic carbon (DOC) available for bacterial growth, and to determine the bacterial growth efficiency (BGE) of natural assemblages. Bacterial growth and DOC consumption were determined in batch culture experiments, in which water samples were supplemented with nitrogen and phosphorus together or separately, or incubated without nutrient additions. When added together, N and P stimulated higher bacterial growth rates and production, as well as higher DOC consumption. The BGEs and DOC consumption rates were strongly dependent on the method used to determine bacterial production. The BGE ranged from 11 to 72%. However, only a minor fraction of bulk DOC was consumed by the planktonic bacteria (from 0.7 to 3.4%). The results suggest that low availability of phosphorus and nitrogen coupled with excess organic carbon was the main factor responsible for the relatively low bacterial utilization of DOC in Imboassica lagoon.
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Affiliation(s)
- V F Farjalla
- Departamento de Ecologia, Instituto de Biologia, CCS, UFRJ, Rio de Janeiro, RJ, 21941-590, Brazil.
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McKenna K, Moorhead D, Roberts E, Laybourn-Parry J. Simulated patterns of carbon flow in the pelagic food web of Lake Fryxell, Antarctica: Little evidence of top-down control. Ecol Modell 2006. [DOI: 10.1016/j.ecolmodel.2005.07.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Caron DA, Countway PD, Brown MV. The growing contributions of molecular biology and immunology to protistan ecology: molecular signatures as ecological tools. J Eukaryot Microbiol 2004; 51:38-48. [PMID: 15068264 DOI: 10.1111/j.1550-7408.2004.tb00159.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Modern genetic and immunological techniques have become important tools for assessing protistan species diversity for both the identification and quantification of specific taxa in natural microbial communities. Although these methods are still gaining use among ecologists, the new approaches have already had a significant impact on our understanding of protistan diversity and biogeography. For example, genetic studies of environmental samples have uncovered many protistan phylotypes that do not match the DNA sequences of any cultured organisms, and whose morphological identities are unknown at the present time. Additionally, rapid and sensitive methods for detecting and enumerating taxa of special importance (e.g. bloom-forming algae, parasitic protists) have enabled much more detailed distributional and experimental studies than have been possible using traditional methods. Nevertheless, while the application of molecular approaches has advanced some aspects of aquatic protistan ecology, significant issues still thwart the widespread adoption of these approaches. These issues include the highly technical nature of some of the molecular methods, the reconciliation of morphology-based and sequence-based species identifications, and the species concept itself.
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Affiliation(s)
- David A Caron
- Department of Biological Sciences, University of Southern California, Los Angeles, California 90089-0371, USA.
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Oguz T, Ducklow HW, Purcell JE, Malanotte-Rizzoli P. Modeling the response of top-down control exerted by gelatinous carnivores on the Black Sea pelagic food web. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/1999jc000078] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Heissenberger A, Leppard GG, Herndl GJ. Relationship between the Intracellular Integrity and the Morphology of the Capsular Envelope in Attached and Free-Living Marine Bacteria. Appl Environ Microbiol 1996; 62:4521-8. [PMID: 16535466 PMCID: PMC1389004 DOI: 10.1128/aem.62.12.4521-4528.1996] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The integrity of the intracellular structures and the presence and dimension of the capsular envelope were investigated in marine snow-associated and marine free-living bacteria by transmission electron microscopy and special fixation techniques. Three categories depending on the presence of internal structures were differentiated. In marine snow, 51% of the marine snow-associated bacterial community was considered intact, 26% had a partly degraded internal structure, and 23% were empty with only the cell wall remaining. For the free-living bacterial community, 34% were intact cells, 42% exhibited damage, and 24% of the cells were lacking any internal structure. We also investigated the morphology and the extent of the bacterial capsular envelope. More than 95% of all intact marine snow-associated bacteria were surrounded by a capsule while (apprx=)55% of empty marine snow-associated bacteria had no capsule. For free-living bacteria, (apprx=)65% of the intact cells had a capsule while (apprx=)80% of the empty free-living bacteria lacked a capsule. Thus there is a clear trend from intact cells which are commonly surrounded by a capsular envelope to empty bacteria for which only the cell wall is remaining. Since bacterioplankton represent the largest living surface in the ocean, it is concluded that the release of intracellular material from bacteria into the environment as well as the release of extracellular capsular material might fuel the dissolved organic matter pool of the ocean.
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Microbiological oceanography in the region west of the Antarctic Peninsula: Microbial dynamics, nitrogen cycle and carbon flux. ACTA ACUST UNITED AC 1996. [DOI: 10.1029/ar070p0303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Wetzel RL. Modeling the microbial loop: An estuarine modeler's perspective. MICROBIAL ECOLOGY 1994; 28:331-334. [PMID: 24186462 DOI: 10.1007/bf00166825] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Contemporary models of the microbial loop should be critically evaluated relative to their compartmental structures, flow networks, and treatment of upper ocean physics (vertical and horizontal boundary conditions). The development of new models that include better representation of the autotrophic components and mixotrophy/competitive interactions is warranted. The mathematical structures should reflect contemporary knowledge of controls (e.g., multiple resource limitation), thresholds and limits, and be based on testable assumptions. Stochastic processes must at some point be included to evaluate known patterns of spatial and temporal variability.
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Affiliation(s)
- R L Wetzel
- Virginia Institute of Marine Science, School of Marine Science, College of William & Mary, 23061, Gloucester Point, Virginia, USA
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Christian RR. Aggregation and disaggregation of microbial food webs. MICROBIAL ECOLOGY 1994; 28:327-329. [PMID: 24186461 DOI: 10.1007/bf00166824] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Models of the microbial food web have generally used compartments aggregated by general body size and gross taxonomy. It has been assumed that these also reflect guilds or holons. Generally, results of simulation or analysis based on this structure have been reasonably well validated. Herein I summarize why the aggregations may be justified and what may be learned from disaggregation.
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Affiliation(s)
- R R Christian
- Biology Department, East Carolina University, 27858, Greenville, North Carolina, USA
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