1
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Stevens BLF, Peacock EE, Crockford ET, Shalapyonok A, Neubert MG, Sosik HM. Distinct responses to warming within picoplankton communities across an environmental gradient. GLOBAL CHANGE BIOLOGY 2024; 30:e17316. [PMID: 38767231 DOI: 10.1111/gcb.17316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 04/01/2024] [Accepted: 04/18/2024] [Indexed: 05/22/2024]
Abstract
Picophytoplankton are a ubiquitous component of marine plankton communities and are expected to be favored by global increases in seawater temperature and stratification associated with climate change. Eukaryotic and prokaryotic picophytoplankton have distinct ecology, and global models predict that the two groups will respond differently to future climate scenarios. At a nearshore observatory on the Northeast US Shelf, however, decades of year-round monitoring have shown these two groups to be highly synchronized in their responses to environmental variability. To reconcile the differences between regional and global predictions for picophytoplankton dynamics, we here investigate the picophytoplankton community across the continental shelf gradient from the nearshore observatory to the continental slope. We analyze flow cytometry data from 22 research cruises, comparing the response of picoeukaryote and Synechococcus communities to environmental variability across time and space. We find that the mechanisms controlling picophytoplankton abundance differ across taxa, season, and distance from shore. Like the prokaryote, Synechococcus, picoeukaryote division rates are limited nearshore by low temperatures in winter and spring, and higher temperatures offshore lead to an earlier spring bloom. Unlike Synechococcus, picoeukaryote concentration in summer decreases dramatically in offshore surface waters and exhibits deeper subsurface maxima. The offshore picoeukaryote community appears to be nutrient limited in the summer and subject to much greater loss rates than Synechococcus. This work both produces and demonstrates the necessity of taxon- and site-specific knowledge for accurately predicting the responses of picophytoplankton to ongoing environmental change.
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Affiliation(s)
- Bethany L F Stevens
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, Santa Barbara, California, USA
| | - Emily E Peacock
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
| | - E Taylor Crockford
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
| | - Alexi Shalapyonok
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
| | - Michael G Neubert
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
| | - Heidi M Sosik
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
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2
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Beckett SJ, Demory D, Coenen AR, Casey JR, Dugenne M, Follett CL, Connell P, Carlson MCG, Hu SK, Wilson ST, Muratore D, Rodriguez-Gonzalez RA, Peng S, Becker KW, Mende DR, Armbrust EV, Caron DA, Lindell D, White AE, Ribalet F, Weitz JS. Disentangling top-down drivers of mortality underlying diel population dynamics of Prochlorococcus in the North Pacific Subtropical Gyre. Nat Commun 2024; 15:2105. [PMID: 38453897 PMCID: PMC10920773 DOI: 10.1038/s41467-024-46165-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 02/16/2024] [Indexed: 03/09/2024] Open
Abstract
Photosynthesis fuels primary production at the base of marine food webs. Yet, in many surface ocean ecosystems, diel-driven primary production is tightly coupled to daily loss. This tight coupling raises the question: which top-down drivers predominate in maintaining persistently stable picocyanobacterial populations over longer time scales? Motivated by high-frequency surface water measurements taken in the North Pacific Subtropical Gyre (NPSG), we developed multitrophic models to investigate bottom-up and top-down mechanisms underlying the balanced control of Prochlorococcus populations. We find that incorporating photosynthetic growth with viral- and predator-induced mortality is sufficient to recapitulate daily oscillations of Prochlorococcus abundances with baseline community abundances. In doing so, we infer that grazers in this environment function as the predominant top-down factor despite high standing viral particle densities. The model-data fits also reveal the ecological relevance of light-dependent viral traits and non-canonical factors to cellular loss. Finally, we leverage sensitivity analyses to demonstrate how variation in life history traits across distinct oceanic contexts, including variation in viral adsorption and grazer clearance rates, can transform the quantitative and even qualitative importance of top-down controls in shaping Prochlorococcus population dynamics.
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Affiliation(s)
- Stephen J Beckett
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
- Department of Biology, University of Maryland, College Park, MD, USA.
| | - David Demory
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
- Sorbonne Université, CNRS, USR 3579, Laboratoire de Biodiversité et Biotechnologies Microbiennes (LBBM), Observatoire Océanologique, Banyuls-sur-Mer, France.
| | - Ashley R Coenen
- School of Physics, Georgia Institute of Technology, Atlanta, GA, USA
| | - John R Casey
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Mathilde Dugenne
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Sorbonne Université, CNRS, UMR 7093, Laboratoire d'Océanographie de Villefranche-sur-Mer (LOV), Villefranche-sur-Mer, France
| | - Christopher L Follett
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Earth, Ocean and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Paige Connell
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
- Biology Department, San Diego Mesa College, San Diego, CA, USA
| | - Michael C G Carlson
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
- Department of Biological Sciences, California State University, Long Beach, CA, USA
| | - Sarah K Hu
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
- Department of Oceanography, Texas A&M University, College Station, TX, USA
| | - Samuel T Wilson
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Daniel Muratore
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
- Santa Fe Institute, Santa Fe, NM, USA
| | | | - Shengyun Peng
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
- Adobe, San Jose, CA, USA
| | - Kevin W Becker
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
- GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Daniel R Mende
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Laboratory of Applied Evolutionary Biology, Department of Medical Microbiology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | | | - David A Caron
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Debbie Lindell
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Angelicque E White
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA
| | - François Ribalet
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - Joshua S Weitz
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
- Department of Biology, University of Maryland, College Park, MD, USA.
- School of Physics, Georgia Institute of Technology, Atlanta, GA, USA.
- Institut de Biologie, École Normale Supérieure, Paris, France.
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3
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Larkin AA, Hagstrom GI, Brock ML, Garcia NS, Martiny AC. Basin-scale biogeography of Prochlorococcus and SAR11 ecotype replication. THE ISME JOURNAL 2023; 17:185-194. [PMID: 36273241 PMCID: PMC9589681 DOI: 10.1038/s41396-022-01332-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 10/03/2022] [Accepted: 10/06/2022] [Indexed: 11/13/2022]
Abstract
Establishing links between microbial diversity and environmental processes requires resolving the high degree of functional variation among closely related lineages or ecotypes. Here, we implement and validate an improved metagenomic approach that estimates the spatial biogeography and environmental regulation of ecotype-specific replication patterns (RObs) across ocean regions. A total of 719 metagenomes were analyzed from meridional Bio-GO-SHIP sections in the Atlantic and Indian Ocean. Accounting for sequencing bias and anchoring replication estimates in genome structure were critical for identifying physiologically relevant biological signals. For example, ecotypes within the dominant marine cyanobacteria Prochlorococcus exhibited distinct diel cycles in RObs that peaked between 19:00-22:00. Additionally, both Prochlorococcus ecotypes and ecotypes within the highly abundant heterotroph Pelagibacter (SAR11) demonstrated systematic biogeographies in RObs that differed from spatial patterns in relative abundance. Finally, RObs was significantly regulated by nutrient stress and temperature, and explained by differences in the genomic potential for nutrient transport, energy production, cell wall structure, and replication. Our results suggest that our new approach to estimating replication is reflective of gross population growth. Moreover, this work reveals that the interaction between adaptation and environmental change drives systematic variability in replication patterns across ocean basins that is ecotype-specific, adding an activity-based dimension to our understanding of microbial niche space.
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Affiliation(s)
- Alyse A Larkin
- Department of Earth System Science, University of California, Irvine, CA, USA
| | - George I Hagstrom
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA
| | - Melissa L Brock
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA, USA
| | - Nathan S Garcia
- Department of Earth System Science, University of California, Irvine, CA, USA
| | - Adam C Martiny
- Department of Earth System Science, University of California, Irvine, CA, USA.
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA, USA.
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4
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Zufia JA, Legrand C, Farnelid H. Seasonal dynamics in picocyanobacterial abundance and clade composition at coastal and offshore stations in the Baltic Sea. Sci Rep 2022; 12:14330. [PMID: 35995823 PMCID: PMC9395346 DOI: 10.1038/s41598-022-18454-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 08/11/2022] [Indexed: 11/11/2022] Open
Abstract
Picocyanobacteria (< 2 µm in diameter) are significant contributors to total phytoplankton biomass. Due to the high diversity within this group, their seasonal dynamics and relationship with environmental parameters, especially in brackish waters, are largely unknown. In this study, the abundance and community composition of phycoerythrin rich picocyanobacteria (PE-SYN) and phycocyanin rich picocyanobacteria (PC-SYN) were monitored at a coastal (K-station) and at an offshore station (LMO; ~ 10 km from land) in the Baltic Sea over three years (2018–2020). Cell abundances of picocyanobacteria correlated positively to temperature and negatively to nitrate (NO3) concentration. While PE-SYN abundance correlated to the presence of nitrogen fixers, PC-SYN abundance was linked to stratification/shallow waters. The picocyanobacterial targeted amplicon sequencing revealed an unprecedented diversity of 2169 picocyanobacterial amplicons sequence variants (ASVs). A unique assemblage of distinct picocyanobacterial clades across seasons was identified. Clade A/B dominated the picocyanobacterial community, except during summer when low NO3, high phosphate (PO4) concentrations and warm temperatures promoted S5.2 dominance. This study, providing multiyear data, links picocyanobacterial populations to environmental parameters. The difference in the response of the two functional groups and clades underscore the need for further high-resolution studies to understand their role in the ecosystem.
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Affiliation(s)
- Javier Alegria Zufia
- Department of Biology and Environmental Science, Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden
| | - Catherine Legrand
- Department of Biology and Environmental Science, Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden.,School of Business, Innovation and Sustainability, Halmstad University, Halmstad, Sweden
| | - Hanna Farnelid
- Department of Biology and Environmental Science, Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden.
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5
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Ducklow H, Cimino M, Dunton KH, Fraser WR, Hopcroft RR, Ji R, Miller AJ, Ohman MD, Sosik HM. Marine Pelagic Ecosystem Responses to Climate Variability and Change. Bioscience 2022. [DOI: 10.1093/biosci/biac050] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
abstract
The marine coastal region makes up just 10% of the total area of the global ocean but contributes nearly 20% of its total primary production and over 80% of fisheries landings. Unicellular phytoplankton dominate primary production. Climate variability has had impacts on various marine ecosystems, but most sites are just approaching the age at which ecological responses to longer term, unidirectional climate trends might be distinguished. All five marine pelagic sites in the US Long Term Ecological Research (LTER) network are experiencing warming trends in surface air temperature. The marine physical system is responding at all sites with increasing mixed layer temperatures and decreasing depth and with declining sea ice cover at the two polar sites. Their ecological responses are more varied. Some sites show multiple population or ecosystem changes, whereas, at others, changes have not been detected, either because more time is needed or because they are not being measured.
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Affiliation(s)
- Hugh Ducklow
- Columbia University , New York, New York, United States
| | - Megan Cimino
- University of California Santa Cruz , Santa Cruz, California, United States
| | - Kenneth H Dunton
- University of Texas, Port Aransas , Port Aransas, Texas, United States
| | - William R Fraser
- Polar Oceans Research Group, part of the Holtzman Wildlife Foundation , Farmington Mills, Michigan, United States
| | | | - Rubao Ji
- Woods Hole Oceanographic Institution , Woods Hole, Massachusetts, United States
| | - Arthur J Miller
- Scripps Institution of Oceanography , La Jolla, California, United States
| | - Mark D Ohman
- Scripps Institution of Oceanography , La Jolla, California, United States
| | - Heidi M Sosik
- Woods Hole Oceanographic Institution , Woods Hole, Massachusetts, United States
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6
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Alegria Zufia J, Farnelid H, Legrand C. Seasonality of Coastal Picophytoplankton Growth, Nutrient Limitation, and Biomass Contribution. Front Microbiol 2021; 12:786590. [PMID: 34938282 PMCID: PMC8685431 DOI: 10.3389/fmicb.2021.786590] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 11/08/2021] [Indexed: 11/13/2022] Open
Abstract
Picophytoplankton in the Baltic Sea includes the simplest unicellular cyanoprokaryotes (Synechococcus/Cyanobium) and photosynthetic picoeukaryotes (PPE). Picophytoplankton are thought to be a key component of the phytoplankton community, but their seasonal dynamics and relationships with nutrients and temperature are largely unknown. We monitored pico- and larger phytoplankton at a coastal site in Kalmar Sound (K-Station) weekly during 2018. Among the cyanoprokaryotes, phycoerythrin-rich picocyanobacteria (PE-rich) dominated in spring and summer while phycocyanin-rich picocyanobacteria (PC-rich) dominated during autumn. PE-rich and PC-rich abundances peaked during summer (1.1 × 105 and 2.0 × 105 cells mL–1) while PPE reached highest abundances in spring (1.1 × 105 cells mL–1). PPE was the main contributor to the total phytoplankton biomass (up to 73%). To assess nutrient limitation, bioassays with combinations of nitrogen (NO3 or NH4) and phosphorus additions were performed. PE-rich and PC-rich growth was mainly limited by nitrogen, with a preference for NH4 at >15°C. The three groups had distinct seasonal dynamics and different temperature ranges: 10°C and 17–19°C for PE-rich, 13–16°C for PC-rich and 11–15°C for PPE. We conclude that picophytoplankton contribute significantly to the carbon cycle in the coastal Baltic Sea and underscore the importance of investigating populations to assess the consequences of the combination of high temperature and NH4 in a future climate.
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Affiliation(s)
- Javier Alegria Zufia
- Marine Phytoplankton Ecology and Applications Laboratory (MPEA), Department of Biology and Environmental Science, Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden
| | - Hanna Farnelid
- Marine Phytoplankton Ecology and Applications Laboratory (MPEA), Department of Biology and Environmental Science, Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden
| | - Catherine Legrand
- Marine Phytoplankton Ecology and Applications Laboratory (MPEA), Department of Biology and Environmental Science, Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden.,School of Business, Innovation and Sustainability, Halmstad University, Halmstad, Sweden
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7
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Hunter-Cevera KR, Hamilton BR, Neubert MG, Sosik HM. Seasonal environmental variability drives microdiversity within a coastal Synechococcus population. Environ Microbiol 2021; 23:4689-4705. [PMID: 34245073 PMCID: PMC8456951 DOI: 10.1111/1462-2920.15666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 04/27/2021] [Accepted: 07/07/2021] [Indexed: 11/29/2022]
Abstract
Marine microbes often show a high degree of physiological or ecological diversity below the species level. This microdiversity raises questions about the processes that drive diversification and permit coexistence of diverse yet closely related marine microbes, especially given the theoretical efficiency of competitive exclusion. Here, we provide insight with an 8‐year time series of diversity within Synechococcus, a widespread and important marine picophytoplankter. The population of Synechococcus on the Northeast U.S. Shelf is comprised of six main types, each of which displays a distinct and consistent seasonal pattern. With compositional data analysis, we show that these patterns can be reproduced with a simple model that couples differential responses to temperature and light with the seasonal cycle of the physical environment. These observations support the hypothesis that temporal variability in environmental factors can maintain microdiversity in marine microbial populations. We also identify how seasonal diversity patterns directly determine overarching Synechococcus population abundance features.
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Affiliation(s)
- Kristen R Hunter-Cevera
- Josephine Bay Paul Center, Marine Biological Laboratory, Woods Hole, MA, USA.,Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Bryan R Hamilton
- Josephine Bay Paul Center, Marine Biological Laboratory, Woods Hole, MA, USA
| | - Michael G Neubert
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Heidi M Sosik
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
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8
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Franklin DJ. Examining the Evidence for Regulated and Programmed Cell Death in Cyanobacteria. How Significant Are Different Forms of Cell Death in Cyanobacteria Population Dynamics? Front Microbiol 2021; 12:633954. [PMID: 33828539 PMCID: PMC8019747 DOI: 10.3389/fmicb.2021.633954] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 02/12/2021] [Indexed: 12/22/2022] Open
Abstract
Cyanobacteria are ancient and versatile members of almost all aquatic food webs. In freshwater ecosystems some cyanobacteria form “bloom” populations containing potent toxins and such blooms are therefore a key focus of study. Bloom populations can be ephemeral, with rapid population declines possible, though the factors causing such declines are generally poorly understood. Cell death could be a significant factor linked to population decline. Broadly, three forms of cell death are currently recognized – accidental, regulated and programmed – and efforts are underway to identify these and standardize the use of cell death terminology, guided by work on better-studied cells. For cyanobacteria, the study of such differing forms of cell death has received little attention, and classifying cell death across the group, and within complex natural populations, is therefore hard and experimentally difficult. The population dynamics of photosynthetic microbes have, in the past, been principally explained through reference to abiotic (“bottom-up”) factors. However, it has become clearer that in general, only a partial linkage exists between abiotic conditions and cyanobacteria population fluctuations in many situations. Instead, a range of biotic interactions both within and between cyanobacteria, and their competitors, pathogens and consumers, can be seen as the major drivers of the observed population fluctuations. Whilst some evolutionary processes may theoretically account for the existence of an intrinsic form of cell death in cyanobacteria, a range of biotic interactions are also likely to frequently cause the ecological incidence of cell death. New theoretical models and single-cell techniques are being developed to illuminate this area. The importance of such work is underlined by both (a) predictions of increasing cyanobacteria dominance due to anthropogenic factors and (b) the realization that influential ecosystem modeling work includes mortality terms with scant foundation, even though such terms can have a very large impact on model predictions. These ideas are explored and a prioritization of research needs is proposed.
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Affiliation(s)
- Daniel J Franklin
- Centre for Ecology, Environment and Sustainability, Department of Life and Environmental Sciences, Faculty of Science and Technology, Bournemouth University, Poole, United Kingdom
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9
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Fowler BL, Neubert MG, Hunter-Cevera KR, Olson RJ, Shalapyonok A, Solow AR, Sosik HM. Dynamics and functional diversity of the smallest phytoplankton on the Northeast US Shelf. Proc Natl Acad Sci U S A 2020; 117:12215-12221. [PMID: 32414929 PMCID: PMC7275697 DOI: 10.1073/pnas.1918439117] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Picophytoplankton are the most abundant primary producers in the ocean. Knowledge of their community dynamics is key to understanding their role in marine food webs and global biogeochemical cycles. To this end, we analyzed a 16-y time series of observations of a phytoplankton community at a nearshore site on the Northeast US Shelf. We used a size-structured population model to estimate in situ division rates for the picoeukaryote assemblage and compared the dynamics with those of the picocyanobacteria Synechococcus at the same location. We found that the picoeukaryotes divide at roughly twice the rate of the more abundant Synechococcus and are subject to greater loss rates (likely from viral lysis and zooplankton grazing). We describe the dynamics of these groups across short and long timescales and conclude that, despite their taxonomic differences, their populations respond similarly to changes in the biotic and abiotic environment. Both groups appear to be temperature limited in the spring and light limited in the fall and to experience greater mortality during the day than at night. Compared with Synechococcus, the picoeukaryotes are subject to greater top-down control and contribute more to the region's primary productivity than their standing stocks suggest.
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Affiliation(s)
- Bethany L Fowler
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543;
| | - Michael G Neubert
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543
- Marine Policy Center, Woods Hole Oceanographic Institution, Woods Hole, MA 02543
| | | | - Robert J Olson
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543
| | - Alexi Shalapyonok
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543
| | - Andrew R Solow
- Marine Policy Center, Woods Hole Oceanographic Institution, Woods Hole, MA 02543
| | - Heidi M Sosik
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543;
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