DOCSLIB.ORG

Microbial Processing of Jellyfish Detritus in the Ocean

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Microbial Processing of Jellyfish Detritus in the Ocean fmicb-11-590995 October 20, 2020 Time: 18:13 # 1 ORIGINAL RESEARCH published: 30 October 2020 doi: 10.3389/fmicb.2020.590995 Microbial Processing of Jellyfish Detritus in the Ocean Tinkara Tinta1,2*, Zihao Zhao1,3, Alvaro Escobar1, Katja Klun2, Barbara Bayer1†, Chie Amano1, Luca Bamonti1 and Gerhard J. Herndl1,3,4* 1 Department of Functional and Evolutionary Ecology, Bio-Oceanography Unit, Faculty of Life Sciences, University of Vienna, Vienna, Austria, 2 Marine Biology Station Piran, National Institute of Biology, Piran, Slovenia, 3 Vienna Metabolomics Center, University of Vienna, Vienna, Austria, 4 Department of Marine Microbiology and Biogeochemistry, Royal Netherlands Institute for Sea Research (NIOZ), Utrecht University, Den Burg, Netherlands When jellyfish blooms decay, sinking jellyfish detrital organic matter (jelly-OM), rich in Edited by: proteins and characterized by a low C:N ratio, becomes a significant source of OM Youhei Yamashita, Hokkaido University, Japan for marine microorganisms. Yet, the key players and the process of microbial jelly- Reviewed by: OM degradation and the consequences for marine ecosystems remain unclear. We Yuya Tada, simulated the scenario potentially experienced by the coastal pelagic microbiome after National Institute for Minamata Disease, Japan the decay of a bloom of the cosmopolitan Aurelia aurita s.l. We show that about half Qi-Long Qin, of the jelly-OM is instantly available as dissolved organic matter and thus, exclusively Shandong University, China and readily accessible to microbes. During a typical decay of an A. aurita bloom in *Correspondence: the northern Adriatic Sea about 100 mg of jelly-OM L−1 becomes available, about Tinkara Tinta −1 −1 [email protected] 44 mmol L as dissolved organic carbon (DOC), 13 mmol L as total dissolved Gerhard J. Herndl nitrogen, 11 mmol L−1 of total hydrolyzable dissolved amino acids (THDAA) and [email protected] −1 3− 0.6 mmol L PO4 . The labile jelly-OM was degraded within 1.5 days (>98% of †Present address: Barbara Bayer, proteins, ∼70% of THDAA, 97% of dissolved free amino acids and the entire jelly- Department of Ecology, Evolution and DOC pool) by a consortium of Pseudoalteromonas, Alteromonas, and Vibrio. These Marine Biology, University of bacteria accounted for 90% of all metabolically active jelly-OM degraders, exhibiting California, Santa Barbara, Santa > Barbara, CA, United States high bacterial growth efficiencies. This implies that a major fraction of the detrital jelly- OM is rapidly incorporated into biomass by opportunistic bacteria. Microbial processing Specialty section: This article was submitted to of jelly-OM resulted in the accumulation of tryptophan, dissolved combined amino acids Aquatic Microbiology, and inorganic nutrients, with possible implications for biogeochemical cycles. a section of the journal Frontiers in Microbiology Keywords: jellyfish blooms, detritus, dissolved organic matter, marine microbial community, biodegradation, proteomics, biogeochemical cycles Received: 03 August 2020 Accepted: 30 September 2020 Published: 30 October 2020 INTRODUCTION Citation: Tinta T, Zhao Z, Escobar A, The complex pool of dissolved organic matter (DOM) in the oceans is one of the largest global Klun K, Bayer B, Amano C, Bamonti L reservoirs of carbon in the biosphere (662 Pg, Hansell et al., 2009). This DOM pool is almost and Herndl GJ (2020) Microbial Processing of Jellyfish Detritus exclusively accessible to diverse members of the microbial community affecting the biogeochemical in the Ocean. state of the ocean and thus the global climate (Azam and Malfatti, 2007). To predict the response of Front. Microbiol. 11:590995. marine ecosystems to natural and anthropogenic perturbations, our understanding on the relation doi: 10.3389/fmicb.2020.590995 between the organic matter (OM) field and the microbial consortia needs to be refined. Frontiers in Microbiology| www.frontiersin.org 1 October 2020| Volume 11| Article 590995 fmicb-11-590995 October 20, 2020 Time: 18:13 # 2 Tinta et al. Microbial Processing of Jellyfish Detritus One significant source of OM in the ocean that has been fragmented by predators and scavengers (Hays et al., 2018), so far largely overlooked are jellyfish (phylum Cnidaria, Class degraded by pelagic microbial communities (Titelman et al., Scyphozoa), which presumably account for >90% of the total 2006; Tinta et al., 2016) and/or massively deposited at the global gelatinous zooplankton biomass, estimated to represent seafloor (Lebrato et al., 2012), where they can be rapidly degraded 0.038 Pg C in the upper 200 m of the ocean (Lucas et al., by benthic communities (West et al., 2009; Sweetman et al., 2014). However, due to sampling biases and lack of data, 2016). Recent estimates on the transfer efficiency of jellyfish the global jellyfish biomass could be largely underestimated biomass indicate that jellyfish are an important component of the (Lebrato et al., 2019). In fact, jellyfish are ubiquitous and biological soft-tissue pump, potentially playing an important role important players in different ecosystems. When conditions as a food source for the food web of the ocean’s interior (Lebrato are favorable some jellyfish species form extensive blooms, et al., 2019). It has been demonstrated that jellyfish carcasses reaching high biomass within a short period of time by efficiently with their proteinaceous character, low C:N ratio and no hard grazing on phytoplankton, zooplankton and fish larvae (Acuña exoskeleton represent a high-quality substrate for specific pelagic et al., 2011; Pitt et al., 2013). Jellyfish blooms are often short- bacteria, altering diversity and functioning of marine food web lived and collapse abruptly due to various largely unexplored (Titelman et al., 2006; Tinta et al., 2012; Blanchet et al., 2015). C 3− environmental factors (Pitt et al., 2014; Schnedler-Meyer et al., Substantial accumulation of NH4 and PO4 has been recorded 2018; Goldstein and Steiner, 2020). Thus, with their “boom and as a result of microbial degradation of jelly-OM in the water bust” population dynamics, jellyfish can represent an important column (Tinta et al., 2010; Blanchet et al., 2015). Altogether, this perturbation to the surrounding ecosystem. Despite of the debate indicates that the pelagic microbial degradation of jelly-OM can over the reported global increase of their blooms and on the be rapid, with important implications for the fate of jelly-OM and actual cause of the observed jellyfish fluctuations, the increase biogeochemical cycles in the ocean. However, the key players and in their population size can have serious socio-economic and the rate and mechanisms of the microbial degradation process of ecological consequences (Richardson et al., 2009; Condon et al., pelagic jelly-OM remain unknown. 2012; Purcell, 2012; Sanz-Martín et al., 2016). It is undisputed, Here, we provide a detailed characterization of detrital however, that jellyfish represent a significant source of OM, jelly-OM and further insights into the processing of jelly-OM especially in coastal ecosystems where large blooms are regularly by microbial communities. To fully understand the nature reported (Kogovšek et al., 2010; Lucas et al., 2014). of the microbial interactions with jelly-OM we have scaled Yet, the link between jellyfish-derived OM and its our investigations down to the molecular level, i.e., the scale most probable consumers and degraders, i.e., the marine relevant for microbially mediated biochemical reactions (Azam microorganisms, has been addressed only by a few studies and Malfatti, 2007). We have characterized the detrital OM of (Titelman et al., 2006; Condon et al., 2011; Blanchet et al., 2015). the cosmopolitan coastal meroplanktonic scyphozoan Aurelia Alive jellyfish release copious amounts of colloidal and labile aurita s.l. on the individual compound level. We link the C-rich DOM via different mechanisms (i.e., sloppy feeding, remineralization rates of different jelly-OM compounds to the fecal pellets and mucus production, and excretion) (Condon metabolic activities of key microbial populations involved in the et al., 2010, 2011). It has been demonstrated that DOM released process. With this approach we ultimately tested the hypothesis by living jellyfish is rapidly respired rather than fueled into that jelly-OM is rapidly degraded by a small, but highly active the biomass production by otherwise rare members of the fraction of the pelagic microbial community. ambient microbial community (Condon et al., 2011; Dinasquet et al., 2013; Manzari et al., 2015). However, the significant fraction of the pelagic biomass that jellyfish incorporate during their life span becomes only available to consumers when MATERIALS AND METHODS jellyfish die. Some studies proposed that the OM release after a massive jellyfish die-off should be even higher and of different Sampling and Pre-processing of Jellyfish stoichiometry than the release from living jellyfish (Pitt et al., Biomass 2009). Jellyfish consist to >95% of water and the organic content Specimens of A. aurita s.l. were collected in the Gulf of Trieste, represents between 20 and 40% of their dry weight (Larson, northern Adriatic, during the senescent phase of their spring 1986; Lucas et al., 2011; Kogovšek et al., 2014), mainly in the 2018 bloom. Altogether, 27 moribund jellyfish specimens were form of proteins (Pitt et al., 2009). This is also reflected by the collected on different days (Supplementary Table S1). The low molar ratio of carbon to nitrogen (C:N = 4.5:1) of jellyfish conditions of the collected jellyfish specimens were evaluated biomass (Kogovšek et al., 2014; Molina-Ramírez et al., 2014). based on their activity (i.e., individuals had reduced bell pulsation Only recently, transcriptome profiling of some jellyfish species rate) and on the stage of their body deformation (i.e., individuals provided the baseline allowing first insights into the complexity had deformed bodies including reduced and/or absent oral arms). of this OM pool (Brekhman et al., 2015). Yet, the release rates Jellyfish were sampled individually from the surface of the water and the detailed biochemical composition of the OM of different column together with ambient seawater using a large acid- jellyfish taxa remain unknown.
Load more

Recommended publications
  • Carbon Dynamics of Subtropical Wetland Communities in South Florida DISSERTATION Presented in Partial Fulfillment of the Require
    Carbon Dynamics of Subtropical Wetland Communities in South Florida DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Jorge Andres Villa Betancur Graduate Program in Environmental Science The Ohio State University 2014 Dissertation Committee: William J. Mitsch, Co-advisor Gil Bohrer, Co-advisor James Bauer Jay Martin Copyrighted by Jorge Andres Villa Betancur 2014 Abstract Emission and uptake of greenhouse gases and the production and transport of dissolved organic matter in different wetland plant communities are key wetland functions determining two important ecosystem services, climate regulation and nutrient cycling. The objective of this dissertation was to study the variation of methane emissions, carbon sequestration and exports of dissolved organic carbon in wetland plant communities of a subtropical climate in south Florida. The plant communities selected for the study of methane emissions and carbon sequestration were located in a natural wetland landscape and corresponded to a gradient of inundation duration. Going from the wettest to the driest conditions, the communities were designated as: deep slough, bald cypress, wet prairie, pond cypress and hydric pine flatwood. In the first methane emissions study, non-steady-state rigid chambers were deployed at each community sequentially at three different times of the day during a 24- month period. Methane fluxes from the different communities did not show a discernible daily pattern, in contrast to a marked increase in seasonal emissions during inundation. All communities acted at times as temporary sinks for methane, but overall were net -2 -1 sources. Median and mean + standard error fluxes in g CH4-C.m .d were higher in the deep slough (11 and 56.2 + 22.1), followed by the wet prairie (9.01 and 53.3 + 26.6), bald cypress (3.31 and 5.54 + 2.51) and pond cypress (1.49, 4.55 + 3.35) communities.
    [Show full text]
  • Phytoplankton As Key Mediators of the Biological Carbon Pump: Their Responses to a Changing Climate
    sustainability Review Phytoplankton as Key Mediators of the Biological Carbon Pump: Their Responses to a Changing Climate Samarpita Basu * ID and Katherine R. M. Mackey Earth System Science, University of California Irvine, Irvine, CA 92697, USA; [email protected] * Correspondence: [email protected] Received: 7 January 2018; Accepted: 12 March 2018; Published: 19 March 2018 Abstract: The world’s oceans are a major sink for atmospheric carbon dioxide (CO2). The biological carbon pump plays a vital role in the net transfer of CO2 from the atmosphere to the oceans and then to the sediments, subsequently maintaining atmospheric CO2 at significantly lower levels than would be the case if it did not exist. The efficiency of the biological pump is a function of phytoplankton physiology and community structure, which are in turn governed by the physical and chemical conditions of the ocean. However, only a few studies have focused on the importance of phytoplankton community structure to the biological pump. Because global change is expected to influence carbon and nutrient availability, temperature and light (via stratification), an improved understanding of how phytoplankton community size structure will respond in the future is required to gain insight into the biological pump and the ability of the ocean to act as a long-term sink for atmospheric CO2. This review article aims to explore the potential impacts of predicted changes in global temperature and the carbonate system on phytoplankton cell size, species and elemental composition, so as to shed light on the ability of the biological pump to sequester carbon in the future ocean.
    [Show full text]
  • From Nano-Gels to Marine Snow: a Synthesis of Gel Formation Processes and Modeling Efforts Involved with Particle Flux in the Ocean
    gels Review From Nano-Gels to Marine Snow: A Synthesis of Gel Formation Processes and Modeling Efforts Involved with Particle Flux in the Ocean Antonietta Quigg 1,* , Peter H. Santschi 2 , Adrian Burd 3, Wei-Chun Chin 4 , Manoj Kamalanathan 1, Chen Xu 2 and Kai Ziervogel 5 1 Department of Marine Biology, Texas A&M University at Galveston, Galveston, TX 77553, USA; [email protected] 2 Department of Marine and Coastal Environmental Science, Texas A&M University at Galveston, Galveston, TX 77553, USA; [email protected] (P.H.S.); [email protected] (C.X.) 3 Department of Marine Science, University of Georgia, Athens, GA 30602, USA; [email protected] 4 Department of Bioengineering, University of California, Merced, CA 95343, USA; [email protected] 5 Institute for the Study of Earth, Oceans and Space, University of New Hampshire, Durham, NH 03824, USA; [email protected] * Correspondence: [email protected] Abstract: Marine gels (nano-, micro-, macro-) and marine snow play important roles in regulating global and basin-scale ocean biogeochemical cycling. Exopolymeric substances (EPS) including transparent exopolymer particles (TEP) that form from nano-gel precursors are abundant materials in the ocean, accounting for an estimated 700 Gt of carbon in seawater. This supports local microbial communities that play a critical role in the cycling of carbon and other macro- and micro-elements in Citation: Quigg, A.; Santschi, P.H.; the ocean. Recent studies have furthered our understanding of the formation and properties of these Burd, A.; Chin, W.-C.; Kamalanathan, materials, but the relationship between the microbial polymers released into the ocean and marine M.; Xu, C.; Ziervogel, K.
    [Show full text]
  • Trends in Soil Solution Dissolved Organic Carbon (DOC) Concentrations Across European Forests
    Biogeosciences, 13, 5567–5585, 2016 www.biogeosciences.net/13/5567/2016/ doi:10.5194/bg-13-5567-2016 © Author(s) 2016. CC Attribution 3.0 License. Trends in soil solution dissolved organic carbon (DOC) concentrations across European forests Marta Camino-Serrano1, Elisabeth Graf Pannatier2, Sara Vicca1, Sebastiaan Luyssaert3,a, Mathieu Jonard4, Philippe Ciais3, Bertrand Guenet3, Bert Gielen1, Josep Peñuelas5,6, Jordi Sardans5,6, Peter Waldner2, Sophia Etzold2, Guia Cecchini7, Nicholas Clarke8, Zoran Galic´9, Laure Gandois10, Karin Hansen11, Jim Johnson12, Uwe Klinck13, Zora Lachmanová14, Antti-Jussi Lindroos15, Henning Meesenburg13, Tiina M. Nieminen15, Tanja G. M. Sanders16, Kasia Sawicka17, Walter Seidling16, Anne Thimonier2, Elena Vanguelova18, Arne Verstraeten19, Lars Vesterdal20, and Ivan A. Janssens1 1Research Group of Plant and Vegetation Ecology, Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium 2WSL, Swiss Federal Institute for Forest, Snow and Landscape Research, Zürcherstrasse 111, 8903, Birmensdorf, Switzerland 3Laboratoire des Sciences du Climat et de l’Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, 91191 Gif-sur-Yvette, France 4UCL-ELI, Université catholique de Louvain, Earth and Life Institute, Croix du Sud 2, 1348 Louvain-la-Neuve, Belgium 5CREAF, Cerdanyola del Vallès, 08193, Catalonia, Spain 6CSIC, Global Ecology Unit CREAF-CSIC-UAB, Cerdanyola del Vallès, 08193, Catalonia, Spain 7Department of Earth Sciences, University of Florence, Via La Pira 4, 50121 Florence,
    [Show full text]
  • Deciphering Ocean Carbon in a Changing World PERSPECTIVE Mary Ann Morana,1, Elizabeth B
    PERSPECTIVE Deciphering ocean carbon in a changing world PERSPECTIVE Mary Ann Morana,1, Elizabeth B. Kujawinskib,1, Aron Stubbinsc,1, Rob Fatlandd,1, Lihini I. Aluwiharee, Alison Buchanf, Byron C. Crumpg, Pieter C. Dorresteinh,i,j, Sonya T. Dyhrmank,l, Nancy J. Hessm, Bill Howen, Krista Longneckerb, Patricia M. Medeirosa, Jutta Niggemanno, Ingrid Obernostererp, Daniel J. Repetab, and Jacob R. Waldbauerq Edited by David M. Karl, University of Hawaii, Honolulu, HI, and approved February 11, 2016 (received for review October 21, 2015) Dissolved organic matter (DOM) in the oceans is one of the largest pools of reduced carbon on Earth, comparable in size to the atmospheric CO2 reservoir. A vast number of compounds are present in DOM, and they play important roles in all major element cycles, contribute to the storage of atmospheric CO2 in the ocean, support marine ecosystems, and facilitate interactions between organisms. At the heart of the DOM cycle lie molecular-level relationships between the individual compounds in DOM and the members of the ocean microbiome that produce and consume them. In the past, these connections have eluded clear definition because of the sheer numerical complexity of both DOM molecules and microorganisms. Emerging tools in analytical chemistry, microbiology, and informatics are breaking down the barriers to a fuller appreciation of these connections. Here we highlight questions being addressed using recent meth- odological and technological developments in those fields and consider how these advances are trans- forming our understanding of some of the most important reactions of the marine carbon cycle. dissolved organic matter | marine microbes | cyberinfrastructure The global cycling of carbon supports life on Earth and and fundamental interactions have been necessarily affects the state of the biosphere within which humans oversimplified to yield a scientifically tractable reside.
    [Show full text]
  • Dissolved Organic Carbon (DOC) (For Private Water and Health Regulated Public Water Supplies)
    Dissolved Organic Carbon (DOC) (For Private Water and Health Regulated Public Water Supplies) What Is Dissolved Organic Carbon? Dissolved organic carbon (DOC) is a general description of the organic material dissolved in water. Organic carbon occurs as the result of decomposition of plant or animal material. Organic carbon present in soil or water bodies may then dissolve when contacted by water. This dissolved organic carbon moves with both surface water and ground water. Acknowledgement: How Does Dissolved Organic Carbon Get Into Water? Organic material (including carbon) results from decomposition of plants or animals. This Fact Sheet is one of a Once this decomposed organic material contacts water it may partially dissolve. series developed by an Interagency Committee with representatives from How Does Dissolved Organic Carbon Affect My Health? Saskatchewan Ministry of DOC does not pose health risk itself but may become potentially harmful when in Health, Regional Health combination with other aspects of your water. When water with high DOC is Authorities, Saskatchewan chlorinated, harmful byproducts called trihalomethanes may be produced (see Watershed Authority, SaskH2O factsheet on trihalomethanes). Trihalomethanes may have long-term Saskatchewan Ministry of effects on health and they should be considered when chlorinating drinking water Environment, Saskatchewan Ministry of Agriculture, high in DOC. According to Health Canada, the benefits of chlorinating drinking Agriculture and Agri-Food water are much greater than the health risks associated with chlorination by- Canada – PFRA and Health products such as trihalomethanes Canada. DOC can interfere with the effectiveness of disinfection processes such as Responsibility for chlorination, ultraviolet and ozone sterilization. DOC can also promote the growth of interpretation of the content of microorganisms by providing a food source.
    [Show full text]
  • The Ballast Effect in the Indian Ocean Tim Rixen1,2, Birgit Gaye2, Kay-Christian Emeis2,3, Venkitasubramani Ramaswamy4
    Biogeosciences Discuss., https://doi.org/10.5194/bg-2017-317 Manuscript under review for journal Biogeosciences Discussion started: 25 August 2017 c Author(s) 2017. CC BY 4.0 License. The Ballast Effect in the Indian Ocean Tim Rixen1,2, Birgit Gaye2, Kay-Christian Emeis2,3, Venkitasubramani Ramaswamy4 1Leibniz Center for Tropical Marine Research, Bremen, 28359, Germany 5 2 Institute of Geology, University of Hamburg, Hamburg, 20146, Germany 3Helmholtz-Zentrum Geesthacht, Institute of Coastal Research, Geesthacht, 21502, Germany 4 National Institute of Oceanography, Dona Paula, Goa, 403004, India Correspondence to: Tim Rixen ([email protected]) Abstract. In this study, data obtained from a sediment trap experiments off South Java are analyzed and compared to 10 satellite-derived information on primary production and data collected by deep-moored sediment traps in the Arabian Sea and the Bay of Bengal. The aim was to study the relative importance of primary production and the ballast effect on the organic carbon export and the CO2 uptake of the biological carbon pumps. Therefore, data obtained from sediment trap experiments carried out in other ocean basins were also integrated into the data analysis and a four-box model was developed. Our data showed that the organic carbon flux in the highly-productive upwelling system in the Arabian Sea was 15 similar to those in the low productive system off South Java. Off South Java as in other river-influenced regions, lithogenic matter supplied from land mainly controls the organic carbon flux via its ballast effect in sinking particles, whereas carbonate produced by marine organisms appears to be the main ballast material in the high productive regions.
    [Show full text]
  • Microbial Loop Carbon Cycling in Ocean Environments Studied Using a Simple Steady-State Model
    AQUATIC MICROBIAL ECOLOGY Vol. 26: 37–49, 2001 Published October 26 Aquat Microb Ecol Microbial loop carbon cycling in ocean environments studied using a simple steady-state model Thomas R. Anderson1,*, Hugh W. Ducklow2 1Southampton Oceanography Centre, Waterfront Campus, European Way, Southampton SO14 3ZH, United Kingdom 2College of William and Mary School of Marine Science, Rte 1208, Box 1346, Gloucester Point, Virginia 23062, USA ABSTRACT: A simple steady-state model is used to examine the microbial loop as a pathway for organic C in marine systems, constrained by observed estimates of bacterial to primary production ratio (BP:PP) and bacterial growth efficiency (BGE). Carbon sources (primary production including extracellular release of dissolved organic carbon, DOC), cycling via zooplankton grazing and viral lysis, and sinks (bacterial and zooplankton respiration) are represented. Model solutions indicate that, at least under near steady-state conditions, recent estimates of BP:PP of about 0.1 to 0.15 are consistent with reasonable scenarios of C cycling (low BGE and phytoplankton extracellular release) at open ocean sites such as the Sargasso Sea and subarctic North Pacific. The finding that bacteria are a major (50%) sink for primary production is shown to be consistent with the best estimates of BGE and dissolved organic matter (DOM) production by zooplankton and phytoplankton. Zooplank- ton-related processes are predicted to provide the greatest supply of DOC for bacterial consumption. The bacterial contribution to C flow in the microbial loop, via bacterivory and viral lysis, is generally low, as a consequence of low BGE. Both BP and BGE are hard to quantify accurately.
    [Show full text]
  • Dissolved Organic Matter in Wetland Soils and Streams Of
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by ScholarWorks@UA DISSOLVED ORGANIC MATTER IN WETLAND SOILS AND STREAMS OF SOUTHEAST ALASKA: SOURCES, CONCENTRATION AND CHEMICAL QUALITY A THESIS Presented to the Faculty of the University of Alaska Fairbanks in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY By Jason B. Fellman, M.S. Fairbanks, Alaska December 2008 iii ABSTRACT Dissolved organic matter (DOM) transported from terrestrial to aquatic ecosystems is an important source of C, N and energy for the metabolism of aquatic heterotrophic bacteria. I examined the concentration and chemical quality of DOM exported from coastal temperate watersheds in southeast Alaska to determine if wetland soils are an important source of biodegradable dissolved organic carbon (BDOC) to aquatic ecosystems. I addressed this question through a combination of high resolution temporal and spatial field measurements in three watersheds near Juneau, Alaska by using a replicated experimental design that characterized DOM export from three different soil types (bog, forested wetland and upland forest) within each of the watersheds. PARAFAC modeling of fluorescence excitation-emission spectroscopy and BDOC incubations were used to evaluate the chemical quality and lability of DOM. Overall, my findings show that wetland soils contribute substantial biodegradable DOM to streams and the response in BDOC delivery to streams changes seasonally, with soil type, and during episodic events such as stormflows. In particular, the chemical quality of DOM in streamwater and soil solution was similar during the spring runoff and fall wet season, as demonstrated by the similar contribution of protein-like fluorescence in soil solution and in streams.
    [Show full text]
  • The Importance of the DOC Pool for Primary Production Estimates
    ICES mar. Sei. Symp., 197: 141-148. 1993 The importance of the DOC pool for primary production estimates George A. Jackson Jackson, G. A. 1993. The importance of the DOC pool for primary production estimates. - ICES mar. Sei. Symp.. 197: 141-148. Phytoplankton release of dissolved organic matter has important consequences for the planktonic ecosystem. Their effects can be compared with those expected at the rates of dissolved organic carbon (DOC) release measured in field incubations. Calculated DOC release rates must be consistent with other incubation measurements, such as those for bacterial growth and for nitrate and ammonia uptake. In this paper, comparisons are made between these different sets of measurements, showing that there is no need for DOC excretion of more than 0.1 of net primary production to account for ecological effects. Furthermore, a simple model of DOC release during productivity measurements shows that grazing on phytoplankton and on bacteria during an incubation can also be important sources of fixed C loss. George A. Jackson: Department of Oceanography, Texas A&M University, College Station, T X 77843, USA. Introduction characterization of DOM has shown it to be quite different in concentration and composition from that In no other part of oceanography have there been as indicated by Sugimura and Suzuki (1988) and Suzuki et many reversals of opinion, doubts about techniques, and al. ( 1985) (Benner et al., 1992). There remains consider­ uncertainties about concentrations and rates as there able uncertainty about the real concentrations of DOC have been associated with dissolved organic matter and DON, but the area remains an active and exciting (DOM) and its constituents dissolved organic carbon part of chemical oceanography (J.
    [Show full text]
  • Soil Organic Carbon Sequestration and Active Carbon Component Changes Following Different Vegetation Restoration Ages on Severely Eroded Red Soils in Subtropical China
    Article Soil Organic Carbon Sequestration and Active Carbon Component Changes Following Different Vegetation Restoration Ages on Severely Eroded Red Soils in Subtropical China Shengsheng Xiao 1,2, Jie Zhang 1,2, Jian Duan 1,2, Hongguang Liu 1,2, Cong Wang 3 and Chongjun Tang 1,2,* 1 Jiangxi Provincial Key Laboratory of Soil Erosion and Prevention, Nanchang 330029, China; [email protected] (S.X.); [email protected] (J.Z.); [email protected] (J.D.); xinongfi[email protected] (H.L.) 2 Jiangxi Institute of Soil and Water Conservation, Nanchang 330029, China 3 State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; [email protected] * Correspondence: [email protected] or [email protected] Received: 4 November 2020; Accepted: 29 November 2020; Published: 4 December 2020 Abstract: Degraded soil has a high carbon sink potential. However, the carbon sequestration capacity and efficiency of comprehensive control measures in soil erosion areas are still not fully understood, and this information is essential for evaluating the effects of adopted restoration measures. The objective of this study was to determine the restoration of soil organic carbon and active carbon components under the impact of soil erosion measures and reforestation following different restoration ages. A small watershed with four typical restored plots following the same control measures (combination measures with horizontal bamboo burl-groove + replanting trees, shrubs and grasses) but different restoration ages (4 years, 14 years, 24 years and 34 years) and two reference plots (bare land (carbon-depleted) and nearby undisturbed forest (carbon-enriched)) in subtropical China was studied.
    [Show full text]
  • Microbial Loop
    Microbial loop The microbial loop describes a trophic pathway in the marine microbial food web where dissolved organic carbon (DOC) is returned to higher trophic levels via its incorporation into bacterial biomass, and then coupled with the classic food chain formed by phytoplankton-zooplankton-nekton. The term microbial loop was coined by Farooq Azam and Tom Fenchel et al.[1] to include the role played by bacteria in the carbon and nutrient cycles of the marine environment. In general, dissolved organic carbon (DOC) is introduced into the ocean environment from bacterial lysis, the leakage or exudation of fixed carbon from phytoplankton (e.g., mucilaginous exopolymer from diatoms), sudden cell senescence, sloppy feeding by zooplankton, the excretion of waste products by aquatic animals, or the breakdown or dissolution of organic particles from terrestrial plants and soils (Van den Meersche et al. 2004). Bacteria in the microbial loop decompose this particulate detritus to utilize this energy-rich matter for growth. Since more than 95% of organic matter in The microbial loop is a marine trophic marine ecosystems consists of polymeric, high molecular pathway which incorporates dissolved weight (HMW) compounds (e.g., protein, polysaccharides, organic carbon into the food chain. lipids), only a small portion of total dissolved organic matter (DOM) is readily utilizable to most marine organisms at higher trophic levels. This means that dissolved organic carbon is not available directly to most marine organisms; marine bacteria introduce this organic carbon into the food web, resulting in additional energy becoming available to higher trophic levels. Recently the term "microbial food web" has been substituted for the term "microbial loop".
    [Show full text]