Archive for community composition

Species loss alters ecosystem function in plankton communities

Posted by mmaheigan 
· Monday, February 8th, 2021 

Climate change impacts on the ocean such as warming, altered nutrient supply, and acidification will lead to significant rearrangement of phytoplankton communities, with the potential for some phytoplankton species to become extinct, especially at the regional level. This leads to the question: What are phytoplankton species’ redundancy levels from ecological and biogeochemical standpoints—i.e. will other species be able to fill the functional ecological and/or biogeochemical roles of the extinct species? Authors of a paper published recently in Global Change Biology explored these ideas using a global three-dimensional computer model with diverse planktonic communities, in which single phytoplankton types were partially or fully eliminated. Complex trophic interactions such as decreased abundance of a predator’s predator led to unexpected “ripples” through the community structure and in particular, reductions in carbon transfer to higher trophic levels. The impacts of changes in resource utilization extended to regions beyond where the phytoplankton type went extinct. Redundancy appeared lowest for types on the edges of trait space (e.g., smallest) or those with unique competitive strategies. These are responses that laboratory or field studies may not adequately capture. These results suggest that species losses could compound many of the already anticipated outcomes of changing climate in terms of productivity, trophic transfer, and restructuring of planktonic communities. The authors also suggest that a combination of modeling, field, and laboratory studies will be the best path forward for studying functional redundancy in phytoplankton.

Figure caption: Examples of the modelled ecological and biogeochemical responses to the extinction of different phytoplankton species.Figure caption: Examples of the modelled ecological and biogeochemical responses to the extinction of different phytoplankton species.

 

Authors:
Stephanie Dutkiewicz (Massachusetts Institute of Technology)
Philip W. Boyd (Institute for Marine and Antarctic Studies, University of Tasmania)
Ulf Riebesell (GEOMAR Helmholtz Centre for Ocean Research Kiel)

Surface bacterial communities respond to rapid changes in the western Arctic

Posted by mmaheigan 
· Tuesday, January 7th, 2020 

During the western Arctic summer open water season, latitudinal differences in the physical and biogeochemical features of the surface water are apparent from the Bering Strait to the Chukchi Borderland. Lower latitude regions (i.e. Bering Strait to Chukchi Shelf) are primarily driven by the inflow of Pacific waters that supply nutrients and heat, leading to high primary production. Conversely, the higher latitude regions (i.e. Chukchi Borderland and Canada Basin) are relatively cold, fresh, and oligotrophic because the surface layer is influenced by freshwater inputs from melting ice and rivers via the Beaufort Gyre. Mixing of the two surface water masses in the western Arctic produces a physicochemical frontal zone (FZ) in the Chukchi Sea.

In a recent study published in Scientific Reports, authors used observations from summer 2017 to investigate latitudinal variations in bacterial community composition in surface waters between the Bering Strait and Chukchi Borderland and the underlying processes driving the changes. Results indicate three distinctive communities: 1) Southern Chukchi (SC) bacterial communities are associated with nutrient-rich conditions, including genera such as Sulfitobacter; 2) a northern Chukchi (NC) bacterial community that dominated by SAR clades, Flavobacterium, Paraglaciecola, and Polaribacter, genera associated with low nutrients and sea ice conditions. If climate-driven changes in the western Arctic continue along the same trajectory, it’s likely we will see altered bacterial communities. If the impact of warm, nutrient-rich Pacific water inflows dominates, it is likely that the productive SC region will expand ­­and the FZ will move northward, leading to nutrient enrichment in the western Arctic (Figure 1). In response, bacterial communities would be dominated by organic matter decomposers, such as Sulfitobacter, due to high primary productivity. However, if the impact of sea-ice meltwater dominates, then the oligotrophic NC region will expand and the FZ will move southward, leading to nutrient depletion in western Arctic surface waters (Figure 1). Continued monitoring in this region will enhance our understanding of how bacterial communities respond (Figure 1b) to a rapidly changing western Arctic Ocean.

Figure 1. (a) Map of the August 2017 Ice Breaker RV Araon western Arctic Ocean sampling stations used in this study. The basemap shows the Chl-a concentration contour (blue to red background colors). Pink, green, and blue circles represent stations in the South Chukchi (SC), Frontal Zone (FZ), and Northern Chukchi (NC) regions. (b) Schematic diagram of surface bacterial community distribution in response to future western Arctic Ocean changes.

Authors:
Il-Nam Kim (Department of Marine Science, Incheon National University)
Sung-Ho Kang (Korea Polar Research Institute)
Eun Jin Yang (Korea Polar Research Institute)

Nutrient and carbon limitation drive broad-scale patterns of mixotrophy in the ocean

Posted by mmaheigan 
· Tuesday, May 14th, 2019 

In the ocean, unicellular eukaryotes are often mixotrophic, which means they photosynthesize and also consume prey. In recent decades, it has become clear that mixotrophs are ubiquitous in sunlit ocean habitats. Additionally, models predict that mixotrophs have important impacts on productivity, nutrient cycling, carbon export, and food web structure. However, there is little understanding of the environmental conditions that select for a mixotrophic lifestyle, and it is unclear how mixotrophs succeed in competition with autotrophic and heterotrophic specialists. A recent study in PNAS that synthesized measurements of mixotrophic nanoflagellates showed that mixotrophs are more abundant in stratified, well-lit, low latitude environments (Figure 1A). They are also more abundant, relative to pure heterotrophs, in productive coastal environments (Figure 1B). A trait-based model analysis revealed that the success of mixotrophs depends on the fact that they are less nutrient-limited than autotrophs (due to prey-derived nutrients) and less carbon-limited than heterotrophs (due to photosynthesis). This synergy requires sufficient light, leading to success in low latitude environments. Similarly, a greater supply of dissolved nutrients relative to prey, as commonly observed in coastal environments, favors mixotrophs relative to heterotrophs. One implication of these results is that carbon fixation at lower latitudes may be enhanced by mixotrophy, while limiting nutrients may be more efficiently transferred to higher trophic levels.

Figure 1. Estimated abundance of autotrophic, mixotrophic, and heterotrophic nanoflagellates across environmental gradients in the ocean.

 

Author:
Kyle Edwards (Univ. Hawaii at Manoa)

WBC Series: Frontiers in western boundary current research

Posted by mmaheigan 
· Friday, November 10th, 2017 

WBC Series Guest Editors: Andrea J. Fassbender1 and Stuart P. Bishop2

1. Monterey Bay Aquarium Research Institute
2. North Carolina State University

Western boundary current (WBC) regions are often studied for their intensity of air-sea interaction and mesoscale variability, yet research addressing the implications of these characteristics for biogeochemical cycling has lagged behind. WBCs, and their extension jets, display a wide breadth of physical processes that give rise to variability ranging from submesoscale (1-10 km) to basin scale (1000 km). WBC extension jets can act as both barriers and conduits for biological and chemical exchanges between subpolar-subtropical water masses, likely serving an important role in local chemical fluxes and biological community composition. Additionally, WBC regions are known for their formation of subtropical mode waters, carrying their source water biogeochemical signatures into the ocean interior. Interactions between (sub)mesoscale processes, mode water formation, and cross frontal exchanges of chemicals and organisms remain an important and nascent area of research.

In addition to the physical dynamics, many questions remain regarding the role of WBC regions in the global carbon cycle. Recent work suggests that these domains exhibit physically mediated export of biogenic particles and are gateways for anthropogenic carbon injection into the ocean interior. Such recent discovery that WBC processes may be strongly linked to the biological carbon pump and anthropogenic carbon storage speaks to the challenges associated with observing these ocean realms. While much has been learned from pairing satellite remote sensing with in situ physical oceanographic observations, biogeochemical analyses have historically been limited by the lack of necessary observing tools. Thus, there remains a critical knowledge gap on the role of WBCs in the global carbon cycle and other biogeochemical cycles.

With OceanObs’19 approximately two years away, the recent Ocean Carbon Hot Spots workshop assessed community interests and perspectives, revealing that it is an opportune time to make use of novel autonomous observing platforms and biogeochemical sensors to unravel some of the mysteries surrounding the role of WBC extensions in marine biogeochemical cycling. The articles herein present some of the most pressing research questions and observing hurdles related to WBCs from the perspectives of physical, chemical, and biological oceanographers and modelers working in this arena.

Series Articles:

Fine-scale biophysical controls on nutrient supply, phytoplankton community structure, and carbon export in western boundary current regions, S. Clayton, P. Gaube, T. Nagai, M.M. Omand, M. Honda

Decadal variability of the Kuroshio Extension system and its impact on subtropical mode water formation B. Qiu, E. Oka, S.P. Bishop, S. Chen, A.J. Fassbender

Western boundary currents as conduits for the ejection of anthropogenic carbon from the thermocline K.B. Rodgers, P. Zhai, D. Iudicone, O. Aumont, B. Carter, A. J. Fassbender, S. M. Griffies, Y. Plancherel, L. Resplandy, R.D. Slater, K. Toyama

The role of western boundary current regions in the global carbon cycle A.R. Gray, J. Palter

Observing air-sea interaction in the western boundary currents and their extension regions: Considerations for OceanObs 2019 D. Zhang, M.F. Cronin, X. Lin, R. Inoue, A.J. Fassbender, S.P. Bishop, A. Sutton

 

US CLIVAR Variations Issue PDF (compiled articles)

Filter by Keyword

234Th disequilibrium abundance acidification africa air-sea interactions air-sea interface algae alkalinity allometry ammonium AMOC anoxia anoxic Antarctic anthro impacts anthropogenic carbon aquaculture aragonite saturation arctic Argo arsenic artificial seawater Atlantic Atlantic modeling atmospheric carbon atmospheric CO2 atmospheric nitrogen deposition authigenic carbonates autonomous platforms bacteria BATS benthic bgc argo bio-go-ship bio-optical bioavailability biogeochemical cycles biogeochemical cycling biogeochemical models biogeochemistry Biological Essential Ocean Variables biological pump biological uptake biophysics bloom blooms blue carbon bottom water boundary layer buffer capacity C14 CaCO3 calcification calcite carbon-climate feedback carbon-sulfur coupling carbon budget carbon cycle carbon dioxide carbon export carbon sequestration carbon storage Caribbean CCA CCS changi changing marine ecosystems changing marine environments changing ocean chemistry chemical oceanographic data chemical speciation chemoautotroph chesapeake bay chl a chlorophyll circulation climate change climate variability CO2 CO2YS coastal darkening coastal ocean cobalt Coccolithophores community composition conservation cooling effect copepod coral reefs CTD currents cyclone data data access data management data product Data standards DCM dead zone decadal trends decomposers decomposition deep convection deep ocean deep sea coral deoxygenation depth diagenesis diatoms DIC diel migration dimethylsulfide dinoflagellate discrete measurements dissolved inorganic carbon dissolved organic carbon DOC DOM domoic acid dust DVM earth system models ecology ecosystems ecosystem state eddy Education Ekman transport emissions ENSO enzyme equatorial regions error ESM estuarine and coastal carbon estuarine and coastal carbon fluxes estuary euphotic zone eutrophication evolution export export fluxes export production EXPORTS extreme events extreme weather events faecal pellets filter feeders filtration rates fire fish Fish carbon fisheries floats fluid dynamics fluorescence food webs forage fish forams freshening freshwater frontal zone fronts functional role future oceans geochemistry geoengineering geologic time GEOTRACES glaciers gliders global carbon budget global ocean global warming go-ship grazing greenhouse gas Greenland groundwater Gulf of Maine Gulf of Mexico Gulf Stream gyre harmful algal bloom high latitude human food human impact hurricane hydrogen hydrothermal hypoxia ice age ice cores ice cover industrial onset inverse circulation ions iron iron fertilization isotopes jellies katabatic winds kelvin waves krill kuroshio laboratory vs field land-ocean continuum larvaceans lateral transport LGM lidar ligands light light attenuation lipids mangroves marine carbon cycle marine heatwave marine snowfall marshes Mediterranean meltwater mesopelagic mesoscale metagenome metals methane methods microbes microlayer microorganisms microscale microzooplankton midwater mixed layer mixed layers mixotrophy modeling models mode water molecular diffusion MPT multi-decade n2o NAAMES NASA NCP net community production net primary productivity new ocean state new technology Niskin bottle nitrate nitrogen nitrogen fixation nitrous oxide north atlantic north pacific nuclear war nutricline nutrient budget nutrient cycling nutrient limitation nutrients OA ocean-atmosphere ocean acidification ocean acidification data ocean carbon uptake and storage ocean color ocean observatories ocean warming ODZ oligotrophic omics OMZ open ocean optics organic particles oscillation overturning circulation oxygen pacific paleoceanography particle flux pCO2 PDO peat pelagic PETM pH phenology phosphorus photosynthesis physical processes physiology phytoplankton PIC plankton POC polar regions pollutants precipitation predation prediction primary production primary productivity Prochlorococcus proteins pteropods pycnocline radioisotopes remineralization remote sensing repeat hydrography residence time resource management respiration resuspension rivers rocky shore Rossby waves Ross Sea ROV salinity salt marsh satell satellite scale seafloor seagrass sea ice sea level rise seasonal patterns seasonal trends sea spray seaweed sediments sensors shelf system shells ship-based observations shorelines silicate sinking particles size SOCCOM soil carbon southern ocean south pacific spatial covariations speciation SST stoichiometry subduction submesoscale subpolar subtropical sulfate surf surface surface ocean Synechococcus teleconnections temperate temperature temporal covariations thermocline thermodynamics thermohaline thorium tidal time-series time of emergence top predators total alkalinity trace elements trace metals trait-based transfer efficiency transient features Tris trophic transfer tropical turbulence twilight zone upper ocean upper water column upwelling US CLIVAR validation velocity gradient ventilation vertical flux vertical migration vertical transport volcano warming water clarity water quality western boundary currents wetlands winter mixing world ocean compilation zooplankton

Copyright © 2022 - OCB Project Office, Woods Hole Oceanographic Institution, 266 Woods Hole Rd, MS #25, Woods Hole, MA 02543 USA Phone: 508-289-2838  •  Fax: 508-457-2193  •  Email: ocb_news@us-ocb.org

link to nsflink to noaalink to WHOI

Funding for the Ocean Carbon & Biogeochemistry Project Office is provided by the National Science Foundation (NSF) and the National Aeronautics and Space Administration (NASA). The OCB Project Office is housed at the Woods Hole Oceanographic Institution.