Animal origins and the Tonian Earth system

2018 ◽  
Vol 2 (2) ◽  
pp. 289-298 ◽  
Author(s):  
Daniel B. Mills ◽  
Warren R. Francis ◽  
Donald E. Canfield
Keyword(s):  
Cellular Differentiation ◽  
Environmental Changes ◽  
Three Dimensional ◽  
Global Ocean ◽  
Ecological Change ◽  
Earth System ◽  
Developmental Constraints ◽  
Low Latitude ◽  
Ecological Changes ◽  
Neoproterozoic Era

The Neoproterozoic Era (1000–541 million years ago, Ma) was characterized by dramatic environmental and evolutionary change, including at least two episodes of extensive, low-latitude glaciation, potential changes in the redox structure of the global ocean, and the origin and diversification of animal life. How these different events related to one another remains an active area of research, particularly how these environmental changes influenced, and were influenced by, the earliest evolution of animals. Animal multicellularity is estimated to have evolved in the Tonian Period (1000–720 Ma) and represents one of at least six independent acquisitions of complex multicellularity, characterized by cellular differentiation, three-dimensional body plans, and active nutrient transport. Compared with the other instances of complex multicellularity, animals represent the only clade to have evolved from wall-less, phagotrophic flagellates, which likely placed unique cytological and trophic constraints on the evolution of animal multicellularity. Here, we compare recent molecular clock estimates with compilations of the chromium isotope, micropaleontological, and organic biomarker records, suggesting that, as of now, the origin of animals was not obviously correlated to any environmental–ecological change in the Tonian Period. This lack of correlation is consistent with the idea that the evolution of animal multicellularity was primarily dictated by internal, developmental constraints and occurred independently of the known environmental–ecological changes that characterized the Neoproterozoic Era.

Pleistocene–Holocene environmental change in the Canary Archipelago as inferred from the stable isotope composition of land snail shells

2011 ◽  
Vol 75 (3) ◽  
pp. 658-669 ◽  
Author(s):  
Yurena Yanes ◽  
Crayton J. Yapp ◽  
Miguel Ibáñez ◽  
María R. Alonso ◽  
Julio De-la-Nuez ◽  
...  
Keyword(s):  
Environmental Change ◽  
Canary Islands ◽  
Environmental Changes ◽  
Isotope Composition ◽  
Moving Average ◽  
Land Snail ◽  
Balance Model ◽  
Low Latitude ◽  
The Times

AbstractThe isotopic composition of land snail shells was analyzed to investigate environmental changes in the eastern Canary Islands (28–29°N) over the last ~ 50 ka. Shell δ13C values range from −8.9‰ to 3.8‰. At various times during the glacial interval (~ 15 to ~ 50 ka), moving average shell δ13C values were 3‰ higher than today, suggesting a larger proportion of C4 plants at those periods. Shell δ18O values range from −1.9‰ to 4.5‰, with moving average δ18O values exhibiting a noisy but long-term increase from 0.1‰ at ~ 50 ka to 1.6–1.8‰ during the LGM (~ 15–22 ka). Subsequently, the moving average δ18O values range from 0.0‰ at ~ 12 ka to 0.9‰ at present. Calculations using a published snail flux balance model for δ18O, constrained by regional temperatures and ocean δ18O values, suggest that relative humidity at the times of snail activity fluctuated but exhibited a long-term decline over the last ~ 50 ka, eventually resulting in the current semiarid conditions of the eastern Canary Islands (consistent with the aridification process in the nearby Sahara). Thus, low-latitude oceanic island land snail shells may be isotopic archives of glacial to interglacial and tropical/subtropical environmental change.

scholarly journals PhytoSFDM version 1.0.0: Phytoplankton Size and Functional Diversity Model

2016 ◽  
Vol 9 (11) ◽  
pp. 4071-4085 ◽  
Author(s):  
Esteban Acevedo-Trejos ◽  
Gunnar Brandt ◽  
S. Lan Smith ◽  
Agostino Merico
Keyword(s):  
Open Source ◽  
Open Source Software ◽  
Marine Ecosystem ◽  
Three Dimensional ◽  
Functional Trait ◽  
Global Ocean ◽  
Total Biomass ◽  
Spatially Resolved ◽  
Phytoplankton Communities ◽  
Natural Complexity

Abstract. Biodiversity is one of the key mechanisms that facilitate the adaptive response of planktonic communities to a fluctuating environment. How to allow for such a flexible response in marine ecosystem models is, however, not entirely clear. One particular way is to resolve the natural complexity of phytoplankton communities by explicitly incorporating a large number of species or plankton functional types. Alternatively, models of aggregate community properties focus on macroecological quantities such as total biomass, mean trait, and trait variance (or functional trait diversity), thus reducing the observed natural complexity to a few mathematical expressions. We developed the PhytoSFDM modelling tool, which can resolve species discretely and can capture aggregate community properties. The tool also provides a set of methods for treating diversity under realistic oceanographic settings. This model is coded in Python and is distributed as open-source software. PhytoSFDM is implemented in a zero-dimensional physical scheme and can be applied to any location of the global ocean. We show that aggregate community models reduce computational complexity while preserving relevant macroecological features of phytoplankton communities. Compared to species-explicit models, aggregate models are more manageable in terms of number of equations and have faster computational times. Further developments of this tool should address the caveats associated with the assumptions of aggregate community models and about implementations into spatially resolved physical settings (one-dimensional and three-dimensional). With PhytoSFDM we embrace the idea of promoting open-source software and encourage scientists to build on this modelling tool to further improve our understanding of the role that biodiversity plays in shaping marine ecosystems.

Electromagnetic fields generated by a three dimensional global ocean circulation

1997 ◽  
Vol 102 (C3) ◽  
pp. 5531-5551 ◽  
Author(s):  
Robert H. Tyler ◽  
Lawrence A. Mysak ◽  
Josef M. Oberhuber
Keyword(s):  
Electromagnetic Fields ◽  
Ocean Circulation ◽  
Three Dimensional ◽  
Global Ocean ◽  
Global Ocean Circulation

scholarly journals Emergence of multiple ocean ecosystem drivers in a large ensemble suite with an Earth system model

2015 ◽  
Vol 12 (11) ◽  
pp. 3301-3320 ◽  
Author(s):  
K. B. Rodgers ◽  
J. Lin ◽  
T. L. Frölicher
Keyword(s):  
Southern Ocean ◽  
Marine Ecosystem ◽  
Marine Ecosystems ◽  
Earth System Model ◽  
System Model ◽  
Global Ocean ◽  
Earth System ◽  
Biological Productivity ◽  
The Tropics ◽  
Ecosystem Drivers

Abstract. Marine ecosystems are increasingly stressed by human-induced changes. Marine ecosystem drivers that contribute to stressing ecosystems – including warming, acidification, deoxygenation and perturbations to biological productivity – can co-occur in space and time, but detecting their trends is complicated by the presence of noise associated with natural variability in the climate system. Here we use large initial-condition ensemble simulations with an Earth system model under a historical/RCP8.5 (representative concentration pathway 8.5) scenario over 1950–2100 to consider emergence characteristics for the four individual and combined drivers. Using a 1-standard-deviation (67% confidence) threshold of signal to noise to define emergence with a 30-year trend window, we show that ocean acidification emerges much earlier than other drivers, namely during the 20th century over most of the global ocean. For biological productivity, the anthropogenic signal does not emerge from the noise over most of the global ocean before the end of the 21st century. The early emergence pattern for sea surface temperature in low latitudes is reversed from that of subsurface oxygen inventories, where emergence occurs earlier in the Southern Ocean. For the combined multiple-driver field, 41% of the global ocean exhibits emergence for the 2005–2014 period, and 63% for the 2075–2084 period. The combined multiple-driver field reveals emergence patterns by the end of this century that are relatively high over much of the Southern Ocean, North Pacific, and Atlantic, but relatively low over the tropics and the South Pacific. For the case of two drivers, the tropics including habitats of coral reefs emerges earliest, with this driven by the joint effects of acidification and warming. It is precisely in the regions with pronounced emergence characteristics where marine ecosystems may be expected to be pushed outside of their comfort zone determined by the degree of natural background variability to which they are adapted. The results underscore the importance of sustained multi-decadal observing systems for monitoring multiple ecosystems drivers.

scholarly journals A parameterization of local and remote tidal mixing

2020 ◽  
Author(s):  
Casimir de Lavergne ◽  
Clément Vic ◽  
Gurvan Madec ◽  
Fabien Roquet ◽  
Amy Waterhouse ◽  
...  
Keyword(s):  
Vertical Mixing ◽  
Three Dimensional ◽  
Internal Tide ◽  
Ocean Model ◽  
Internal Tides ◽  
Tidal Mixing ◽  
Global Ocean ◽  
Energy Conserving ◽  
Energy Constrained ◽  
Lagrangian Tracking

<p>Vertical mixing is often regarded as the Achilles’ heel of ocean models. In particular, few models include a comprehensive and energy-constrained parameterization of mixing by internal ocean tides. Here, we present an energy-conserving mixing scheme which accounts for the local breaking of high-mode internal tides and the distant dissipation of low-mode internal tides. The scheme relies on four static two-dimensional maps of internal tide dissipation, constructed using mode-by-mode Lagrangian tracking of energy beams from sources to sinks. Each map is associated with a distinct dissipative process and a corresponding vertical structure. Applied to an observational climatology of stratification, the scheme produces a global three-dimensional map of dissipation which compares well with available microstructure observations and with upper-ocean finestructure mixing estimates. Implemented in the NEMO global ocean model, the scheme improves the representation of deep water-mass transformation and obviates the need for a constant background diffusivity.</p>

Chrysophyte microfossils record marked responses to recent environmental changes in high- and mid-arctic lakes

2001 ◽  
Vol 79 (6) ◽  
pp. 747-752 ◽  
Author(s):  
Alexander P Wolfe ◽  
Bianca B Perren
Keyword(s):  
Environmental Changes ◽  
Arctic Lakes ◽  
Ice Age ◽  
Algal Community ◽  
North Coast ◽  
Baffin Island ◽  
Lake Ecosystems ◽  
The North ◽  
Ecological Changes ◽  
Community Shifts

Rapid stratigraphic changes are recorded in recent assemblages of subfossil Chrysophyceae from the sediments of two highly contrasted arctic lakes, one situated in the polar desert of west-central Ellesmere Island, and the other on eastern Baffin Island in the mid-Arctic climatic zone. In Sawtooth Lake on the Fosheim Peninsula, concentrations of chrysophycean stomatocysts increase dramatically in sediments deposited since AD 1920. Only trace abundances of stomatocysts are encountered in older sediments. In Kekerturnak Lake, on the north coast of Cumberland Peninsula, scales of Mallomonas spp., previously absent from the sediment record, appear suddenly in the upper 5.5 cm of sediment and subsequently become ubiquitous in the top 1.0 cm. These results corroborate diatom stratigraphic data from other sites in the Canadian Arctic Archipelago, together suggesting that unprecedented ecological changes are presently occurring across this vast region. In all likelihood, these abrupt algal community shifts reflect the response of arctic lake ecosystems to well-documented climate warming since the Little Ice Age, with the implications that recent rates of environmental change are unprecedented in the context of the Holocene.Key words: Paleolimnology, arctic lakes, Chrysophyceae, stomatocysts, Mallomonas.

Development of a Coupled 3D Groundwater-Vegetation Model for Coastal Wetlands

2021 ◽  
Author(s):  
Shuxin Luo ◽  
Ting Fong May Chui
Keyword(s):  
Native Species ◽  
Environmental Changes ◽  
Southern China ◽  
Saline Water ◽  
Three Dimensional ◽  
Mangrove Ecosystem ◽  
Mangrove Forests ◽  
Vegetation Model ◽  
Mangrove Species ◽  
Hydrological Conditions

<p>Mangrove forests are mainly found in the intertidal zone. Their ability to live in saline water enables them to outcompete non-mangrove vegetation in harsh and specific coastal environment. Nevertheless, they can still be invaded by alien mangrove species in suitable hydrological conditions, possibly resulting in more fragile ecosystems. Subtropical mangrove ecosystem demonstrates high variability in mangrove growth and hydrological conditions. However, their interactions are not well-understood, especially for the mangrove interspecific competition in varying groundwater conditions. To address this issue, the present study developed a coupled three-dimensional groundwater-vegetation model based on MANTRA (MANHAM-SUTRA) to simultaneously simulate groundwater hydrodynamics and mangrove distribution. The developed model was then applied to a subtropical mangrove swamp invaded by Sonneratia spp. in Mai Po Nature Reserve, Hong Kong, China. Vegetation domain is updated yearly using the annual mangrove areas extracted from remote-sensing images from 2000 to 2018. Then, multidecadal simulations were performed to validate the model in simulating the interaction between groundwater and mangrove growth. For the piezometric head, all RMS errors are smaller than 0.2 m and the correlation coefficients are larger than 0.86, which proves the effectiveness of the model in groundwater level simulation within Mai Po. The seasonal variations in the groundwater salinity were also well captured in both the fringe forest and the mudflat. The simulated biomass of Sonneratia spp. is mainly distributed at the river outlets, which is also in good agreement with the historical measurements. The validated model can then be used to predict the invasion and the distribution of the exotic mangrove species in the context of future environmental changes for better management of mangrove swamps. Since Sonneratia is a common alien species in southern China, the model can also be used for regional management of mangrove invasion and conservation of native species. The insights obtained from this study may also provide references for other similar studies examining the interaction between coastal groundwater and vegetation.</p>

scholarly journals CAS-ESM2.0 Model Datasets for the CMIP6 Ocean Model Intercomparison Project Phase 1 (OMIP1)

2020 ◽  
Author(s):  
Xiao Dong ◽  
Jiangbo Jin ◽  
Hailong Liu ◽  
He Zhang ◽  
Minghua Zhang ◽  
...  
Keyword(s):  
Sea Ice ◽  
Phase 1 ◽  
Ocean Model ◽  
Meridional Overturning Circulation ◽  
Sea Surface ◽  
Global Ocean ◽  
Quasi Equilibrium ◽  
Earth System ◽  
Model Intercomparison ◽  
Intercomparison Project

AbstractAs a member of the Chinese modeling groups, the coupled ocean-ice component of the Chinese Academy of Sciences’ Earth System Model, version 2.0 (CAS-ESM2.0), is taking part in the Ocean Model Intercomparison Project Phase 1 (OMIP1) experiment of phase 6 of the Coupled Model Intercomparison Project (CMIP6). The simulation was conducted, and monthly outputs have been published on the ESGF (Earth System Grid Federation) data server. In this paper, the experimental dataset is introduced, and the preliminary performances of the ocean model in simulating the global ocean temperature, salinity, sea surface temperature, sea surface salinity, sea surface height, sea ice, and Atlantic Meridional Overturning Circulation (AMOC) are evaluated. The results show that the model is at quasi-equilibrium during the integration of 372 years, and performances of the model are reasonable compared with observations. This dataset is ready to be downloaded and used by the community in related research, e.g., multi-ocean-sea-ice model performance evaluation and interannual variation in oceans driven by prescribed atmospheric forcing.

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