scholarly journals The global ocean size-spectrum from bacteria to whales

2021 ◽  
Author(s):  
Ian A Hatton ◽  
Ryan F Heneghan ◽  
Yinon M Bar-On ◽  
Eric D Galbraith
Keyword(s):  
Human Impacts ◽  
Global Scale ◽  
Global Ocean ◽  
Size Spectrum ◽  
Marine Life ◽  
Size Classes ◽  
Aquatic Biomass ◽  
Order Of Magnitude ◽  
Mass Size ◽  
Wet Weight

It has long been hypothesized that aquatic biomass is evenly distributed among logarithmic body mass size-classes. Although this community structure has been observed locally among plankton groups, its generality has never been formally tested across all marine life, nor have its impacts by humans been broadly assessed. Here, we bring together data at the global scale to test the hypothesis from bacteria to whales. We find that biomass within most order of magnitude size-classes is indeed remarkably constant, near 1 Gt wet weight (10^15 grams), but that bacteria and whales are markedly above and below this value, respectively. Furthermore, human impacts have significantly truncated the upper one-third of the spectrum. Size-spectrum theory has yet to provide an explanation for what is possibly life's largest scale regularity.

5. Marine life in the tropics

2020 ◽  
pp. 87-114
Author(s):  
Philip V. Mladenov
Keyword(s):  
Coral Reefs ◽  
Marine Environment ◽  
Biological Diversity ◽  
Human Impacts ◽  
Global Scale ◽  
Global Ocean ◽  
Natural Systems ◽  
Marine Life ◽  
Economic Significance ◽  
The Tropics

The tropical marine environment encompasses those parts of the Global Ocean where the surface waters are consistently warm throughout the year, rarely falling below 20°C. Coral reefs embody the archetypal image of a tropical marine environment and are globally significant natural systems in terms of their beauty, biological diversity, productivity, and economic significance. ‘Marine life in the tropics’ explains the physical requirements, biology, and productivity of coral reefs. It discusses the physical and biological disturbances on coral reefs that can cause their destruction along with the local-, regional-, and global-scale human impacts on coral reefs before considering the future of coral reefs.

scholarly journals A Global Ocean Biogeographic Information System (OBIS) for the Census of Marine Life

Oceanography ◽  
1999 ◽  
Vol 12 (3) ◽  
pp. 12-14 ◽  
Author(s):  
J. Frederick Grassle ◽  
Karen Stocks
Keyword(s):  
Information System ◽  
Global Ocean ◽  
Marine Life

scholarly journals Microbial bioenergetics of coral-algal interactions

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3423 ◽  
Author(s):  
Ty N.F. Roach ◽  
Maria L. Abieri ◽  
Emma E. George ◽  
Ben Knowles ◽  
Douglas S. Naliboff ◽  
...  
Keyword(s):  
Power Output ◽  
Energy Use ◽  
Human Impacts ◽  
Global Scale ◽  
Trophic Levels ◽  
Maximal Power Output ◽  
Bioenergetic Analysis ◽  
Lower Oxygen ◽  
Thermodynamic Mechanism ◽  
Oxygen Concentrations

Human impacts are causing ecosystem phase shifts from coral- to algal-dominated reef systems on a global scale. As these ecosystems undergo transition, there is an increased incidence of coral-macroalgal interactions. Mounting evidence indicates that the outcome of these interaction events is, in part, governed by microbially mediated dynamics. The allocation of available energy through different trophic levels, including the microbial food web, determines the outcome of these interactions and ultimately shapes the benthic community structure. However, little is known about the underlying thermodynamic mechanisms involved in these trophic energy transfers. This study utilizes a novel combination of methods including calorimetry, flow cytometry, and optical oxygen measurements, to provide a bioenergetic analysis of coral-macroalgal interactions in a controlled aquarium setting. We demonstrate that the energetic demands of microbial communities at the coral-algal interaction interface are higher than in the communities associated with either of the macroorganisms alone. This was evident through higher microbial power output (energy use per unit time) and lower oxygen concentrations at interaction zones compared to areas distal from the interface. Increases in microbial power output and lower oxygen concentrations were significantly correlated with the ratio of heterotrophic to autotrophic microbes but not the total microbial abundance. These results suggest that coral-algal interfaces harbor higher proportions of heterotrophic microbes that are optimizing maximal power output, as opposed to yield. This yield to power shift offers a possible thermodynamic mechanism underlying the transition from coral- to algal-dominated reef ecosystems currently being observed worldwide. As changes in the power output of an ecosystem are a significant indicator of the current state of the system, this analysis provides a novel and insightful means to quantify microbial impacts on reef health.

scholarly journals Global ocean dimethyl sulfide climatology estimated from observations and an artificial neural network

2020 ◽  
Author(s):  
Wei-Lei Wang ◽  
Guisheng Song ◽  
François Primeau ◽  
Eric S. Saltzman ◽  
Thomas G. Bell ◽  
...  
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Solar Radiation ◽  
Mixed Layer ◽  
Dimethyl Sulfide ◽  
Mixed Layer Depth ◽  
Environmental Parameters ◽  
Global Scale ◽  
Global Ocean ◽  
Layer Depth

Abstract. Marine dimethyl sulfide (DMS) is important to climate due to the ability of DMS to alter Earth's radiation budget. However, a knowledge of the global-scale distribution, seasonal variability, and sea-to-air flux of DMS is needed in order to understand the factors controlling surface ocean DMS and its impact on climate. Here we examine the use of an artificial neural network (ANN) to extrapolate available DMS measurements to the global ocean and produce a global climatology with monthly temporal resolution. A global database of 57 810 ship-based DMS measurements in surface waters was used along with a suite of environmental parameters consisting of lat-lon coordinates, time-of-day, time-of-year, solar radiation, mixed layer depth, sea surface temperature, salinity, nitrate, phosphate, silicate, and oxygen. Linear regressions of DMS against the environmental parameters show that on a global scale mixed layer depth and solar radiation are the strongest predictors of DMS, however, they capture 14 % and 12 % of the raw DMS data variance, respectively. The multi-linear regression can capture more (∼29 %) of the raw data variance, but strongly underestimates high DMS concentrations. In contrast, the ANN captures ~61 % of the raw data variance in our database. Like prior climatologies our results show a strong seasonal cycle in DMS concentration and sea-to-air flux. The highest concentrations (fluxes) occur in the high-latitude oceans during the summer. We estimate a lower global sea-to-air DMS flux (17.90 ± 0.34 Tg S yr−1) than the prior estimate based on a map interpolation method when the same gas transfer velocity parameterization is used.

scholarly journals Different processes shape prokaryotic and picoeukaryotic assemblages in the sunlit ocean microbiome

2018 ◽  
Author(s):  
Ramiro Logares ◽  
Ina M. Deutschmann ◽  
Caterina. R. Giner ◽  
Anders K. Krabberød ◽  
Thomas S. B. Schmidt ◽  
...  
Keyword(s):  
Ecosystem Function ◽  
Sequence Data ◽  
Scale Effects ◽  
Dispersal Limitation ◽  
Global Scale ◽  
Global Ocean ◽  
Ecosystem Functions ◽  
Ecological Processes ◽  
Surface Ocean

ABSTRACTThe smallest members of the sunlit-ocean microbiome (prokaryotes and picoeukaryotes) participate in a plethora of ecosystem functions with planetary-scale effects. Understanding the processes determining the spatial turnover of this assemblage can help us better comprehend the links between microbiome species composition and ecosystem function. Ecological theory predicts thatselection,dispersalanddriftare main drivers of species distributions, yet, the relative quantitative importance of these ecological processes in structuring the surface-ocean microbiome is barely known. Here we quantified the role of selection, dispersal and drift in structuring surface-ocean prokaryotic and picoeukaryotic assemblages by using community DNA-sequence data collected during the global Malaspina expedition. We found that dispersal limitation was the dominant process structuring picoeukaryotic communities, while a balanced combination of dispersal limitation, selection and drift shaped prokaryotic counterparts. Subsequently, we determined the agents exerting abiotic selection as well as the spatial patterns emerging from the action of different ecological processes. We found that selection exerted via temperature had a strong influence on the structure of prokaryotic communities, particularly on species co-occurrences, a pattern not observed among communities of picoeukaryotes. Other measured abiotic variables had limited selective effects on microbiome structure. Picoeukaryotes presented a higher differentiation between neighbouring communities and a higher distance-decay when compared to prokaryotes, agreeing with their higher dispersal limitation. Finally, drift seemed to have a limited role in structuring the sunlit-ocean microbiome. The different predominance of ecological processes acting on particular subsets of the ocean microbiome suggests uneven responses to environmental change.SIGNIFICANCE STATEMENTThe global ocean contains one of the largest microbiomes on Earth and changes on its structure can impact the functioning of the biosphere. Yet, we are far from understanding the mechanisms that structure the global ocean microbiome, that is, the relative importance of environmentalselection,dispersaland random events (drift). We evaluated the role of these processes at the global scale, based on data derived from a circumglobal expedition and found that these ecological processes act differently on prokaryotes and picoeukaryotes, two of the main components of the ocean microbiome. Our work represents a significant contribution to understand the assembly of marine microbial communities, providing also insights on the links between ecological mechanisms, microbiome structure and ecosystem function.

Geochemical peat records from the Great Vasyugan Mire and Tomsk region, Siberia. Regional temporal trend of human impact over the last 500 years and local perturbations.

2021 ◽  
Author(s):  
Simon Hutchinson ◽  
Andrei Diaconu ◽  
Sergey Kirpotin ◽  
Angelica Feurdean
Keyword(s):  
Trace Element ◽  
Forest Cover ◽  
Human Impacts ◽  
Global Scale ◽  
Testate Amoeba ◽  
Dust Deposition ◽  
Peat Core ◽  
Element Concentrations ◽  
Local Perturbations ◽  
Geochemical Profile

<p>Although interest in peatland environments, especially in terms of their carbon storage, has gained momentum in response to a heightened awareness of the climate emergency; significant gaps remain in the geographical coverage of our knowledge of mires, including some major wetland systems. This paucity has implications, not only for our understanding of their development and functioning, but also for adequately predicting future changes and thus providing effective mire environmental management. Our INTERACT-supported study provides radiometrically dated, well-characterised millennial scale peat records from two contrasting undisturbed and impacted (ditched) ombrotrophic sites in the Great Vasyugan Mire (GVM) near Tomsk, Siberia and two additional mesotrophic sites to the east of the Ob river. In addition, the geochemical record was complemented by multiproxy palaeoecological characterisation (pollen, charcoal, stable isotopes, testate amoeba). We identified both natural (lithogenic) and anthropogenic geochemical signals recording human impacts with site specific variations. Elevated trace element concentrations in the peat profiles align with the region’s wider agricultural and economic development following the colonisation of Siberia by Russia (from ca. 1600 AD) when pollen assemblages indicate the decline of forest cover and an increase in human disturbance, including the use for fire. Trace element concentrations peak with the subsequent, post WWII industrialisation of regional centres in southern Siberia (after 1950 AD). On a global scale, our sites, together with evidence from the few other comparable studies in the region, suggest that the region’s peatlands are relatively uncontaminated by human activities with a mean lead (Pb) level of < 5 mg/kg. However, via lithogenic elements including Rb, Ti and Zr, we detected both a geochemical signal as a result of historical land cover changes enhancing mineral dust deposition following disturbance, as well as fossil fuel derived pollutants as relatively elevated, subsurface As and Pb concentrations of ca. 10 and 25 mg/kg respectively with the development of industry in the region. Nevertheless, the potential significance of local factors on the sites’ geochemical profile is also highlighted. For example, we identify the effects of past peat drainage for afforestation (ca. 1960s) and the scheme’s subsequent abandonment. Although the region’s mire systems are remote and vast, they appear to hold a legacy of human activity that can be detected as a geochemical signal supporting the inferences of other palaeoenvironmental proxies. Such geochemical peat core records, from Eurasia in particular, remain relatively scarce in the international scientific literature and therefore, as yet, inadequately characterised and quantified compared to other regions.</p>

7. Intertidal life

2020 ◽  
pp. 135-146
Author(s):  
Philip V. Mladenov
Keyword(s):  
Air Temperature ◽  
Physical Environment ◽  
Human Impacts ◽  
Marine Organisms ◽  
Global Ocean ◽  
Thin Strip ◽  
Temperature Extremes ◽  
Wide Range ◽  
Marine Community

The intertidal region of the Global Ocean is a thin strip of shoreline lying between the high and low tide marks; it is completely submerged by seawater at the highest high tides and completely uncovered at the lowest low tides. The intertidal region is occupied almost exclusively by marine organisms that have adapted to live in a very stressful physical environment influenced by exposure to air, temperature extremes, wind, and the pounding of waves. This region is home to a diverse and interesting marine community that is easy to study and enjoy due to its accessibility. It is also a place where people routinely harvest seafood, and is prone to a wide range of human impacts.

Global Ocean Meridional Overturning

2007 ◽  
Vol 37 (10) ◽  
pp. 2550-2562 ◽  
Author(s):  
Rick Lumpkin ◽  
Kevin Speer
Keyword(s):  
Ocean Circulation ◽  
Global Scale ◽  
The Arctic ◽  
Global Ocean ◽  
Mixing Processes ◽  
Boundary Currents ◽  
Antarctic Continent ◽  
Meridional Overturning ◽  
Global Ocean Circulation ◽  
The Antarctic

Abstract A decade-mean global ocean circulation is estimated using inverse techniques, incorporating air–sea fluxes of heat and freshwater, recent hydrographic sections, and direct current measurements. This information is used to determine mass, heat, freshwater, and other chemical transports, and to constrain boundary currents and dense overflows. The 18 boxes defined by these sections are divided into 45 isopycnal (neutral density) layers. Diapycnal transfers within the boxes are allowed, representing advective fluxes and mixing processes. Air–sea fluxes at the surface produce transfers between outcropping layers. The model obtains a global overturning circulation consistent with the various observations, revealing two global-scale meridional circulation cells: an upper cell, with sinking in the Arctic and subarctic regions and upwelling in the Southern Ocean, and a lower cell, with sinking around the Antarctic continent and abyssal upwelling mainly below the crests of the major bathymetric ridges.

Fog Droplet Deposition and Coarse Water Formation in Low-Pressure Steam Turbines: A Combined Experimental and Theoretical Analysis

1988 ◽  
Vol 110 (2) ◽  
pp. 163-172 ◽  
Author(s):  
J. B. Young ◽  
K. K. Yau ◽  
P. T. Walters
Keyword(s):  
Size Spectrum ◽  
Steam Turbines ◽  
Droplet Deposition ◽  
Deposition Rates ◽  
Water Formation ◽  
Pressure Steam ◽  
Order Of Magnitude ◽  
Droplet Sizes ◽  
Inversion Procedure ◽  
Last Stage

The paper describes a theoretical and experimental study of fog droplet deposition and coarse water formation in the LP cylinders of two 500 MW steam turbines. Measurements of coarse water flow rates entering and leaving the final stage of each turbine were performed using a new design of water absorbent probe. From these measurements it was possible to deduce the rate of deposition of fog droplets onto the last stage blading of each machine. Aerodynamic and optical traverses provided experimental data on the fog droplet mean diameter and wetness faction, and the application of an inversion procedure generated an approximation to the droplet size spectrum itself. Using these data and theoretical methods for predicting inertial and diffusional deposition rates, a second estimate was obtained for the stage deposition rates. The two different approaches show excellent agreement, in contrast with previously published work, which was unable to reconcile (to within one order of magnitude) deposition theory with measured fog droplet sizes and coarse water quantities.

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