Freshwater input, upwelling, and the evolution of Caribbean coastal ecosystems during formation of the Isthmus of Panama

Geology ◽  
2019 ◽  
Vol 47 (9) ◽  
pp. 857-861 ◽  
Author(s):  
Ethan L. Grossman ◽  
John A. Robbins ◽  
Paola G. Rachello-Dolmen ◽  
Kai Tao ◽  
Divya Saxena ◽  
...  
Keyword(s):  
Planktonic Foraminifera ◽  
Coastal Ecosystems ◽  
Intertropical Convergence Zone ◽  
Paleoenvironmental Reconstruction ◽  
Freshwater Input ◽  
Nutrient Input ◽  
Isthmus Of Panama ◽  
Southward Shift ◽  
Coastal Shelf ◽  
Modern Reef

Abstract Caribbean biota underwent major ecological and evolutionary transformation in the Pliocene–Pleistocene, but a lack of detailed paleoenvironmental reconstruction prevents thorough resolution of cause and effect. We quantify levels of upwelling and freshwater input into Caribbean coastal shelf ecosystems over the last ∼6 m.y. with >3300 stable isotope measurements from 74 fossil serially sampled gastropods by normalizing δ18O values to open-ocean δ18O from planktonic foraminifera. We find that the influence of Pacific-like upwelling in the southwestern Caribbean was low after 4.25 Ma but coastal ecosystems were heavily influenced by seasonal freshening until ca. 2.5 Ma, after which time low-freshwater conditions were established. The origination of modern oligotrophic coastal conditions was therefore a result of oceanographic change causing declining upwelling, and declining nutrients from terrestrial sources. We speculate that a southward shift of the Intertropical Convergence Zone, associated with Northern Hemisphere glaciation, reduced rainfall and terrestrial nutrient input and contributed to biotic turnover in the southwestern Caribbean, including the proliferation of modern reef communities.

ERRATUM: Freshwater input, upwelling, and the evolution of Caribbean coastal ecosystems during formation of the Isthmus of Panama

Geology ◽  
2021 ◽  
Author(s):  
Ethan L. Grossman ◽  
John A. Robbins ◽  
Paola G. Rachello-Dolmen ◽  
Kai Tao ◽  
Divya Saxena ◽  
...  
Keyword(s):  
Coastal Ecosystems ◽  
Freshwater Input ◽  
Isthmus Of Panama

Note that Ethan L. Grossman and Aaron O’Dea contributed equally to this work.

Abrupt CO2 release to the atmosphere under glacial and early interglacial climate conditions

Science ◽  
2020 ◽  
Vol 369 (6506) ◽  
pp. 1000-1005
Author(s):  
C. Nehrbass-Ahles ◽  
J. Shin ◽  
J. Schmitt ◽  
B. Bereiter ◽  
F. Joos ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Intertropical Convergence Zone ◽  
Meridional Overturning Circulation ◽  
Before Present ◽  
Freshwater Input ◽  
Warm Climate ◽  
Climate Conditions ◽  
Carbon Dioxide Release ◽  
Meridional Overturning ◽  
Co2 Release

Pulse-like carbon dioxide release to the atmosphere on centennial time scales has only been identified for the most recent glacial and deglacial periods and is thought to be absent during warmer climate conditions. Here, we present a high-resolution carbon dioxide record from 330,000 to 450,000 years before present, revealing pronounced carbon dioxide jumps (CDJ) under cold and warm climate conditions. CDJ come in two varieties that we attribute to invigoration or weakening of the Atlantic meridional overturning circulation (AMOC) and associated northward and southward shifts of the intertropical convergence zone, respectively. We find that CDJ are pervasive features of the carbon cycle that can occur during interglacial climate conditions if land ice masses are sufficiently extended to be able to disturb the AMOC by freshwater input.

Upper-ocean stratification of the NE South China Sea during the last 35 ka: Implications from oxygen isotope records from planktonic foraminifera

2020 ◽  
Author(s):  
Tzu-Chun Wang ◽  
Andrew Tien-Shun Lin ◽  
Horng-Sheng Mii ◽  
Chorng-Shern Horng ◽  
Christophe Colin
Keyword(s):  
High Resolution ◽  
South China Sea ◽  
Oxygen Isotope ◽  
Sediment Core ◽  
South China ◽  
Planktonic Foraminifera ◽  
Upper Ocean ◽  
Freshwater Input ◽  
Ocean Stratification ◽  
China Sea

<p>The sedimentation rate in the northeastern South China Sea (SCS) is high and it therefore offers an opportunity for a high-resolution paleoceanographic study. This study is based on high-resolution AMS <sup>14</sup>C dating on forams and oxygen isotope data of two planktonic foraminifera species (<em>Globigerinoides ruber</em> and <em>Neogloboquadrina dutertrei</em>) from the sediment core, MD18-3568, collected from the northeastern SCS, to reconstruct upper-ocean stratification since 35 ka.</p><p>The marine sediment core MD18-3568 is located on the accretionary wedge off SW Taiwan at a water depth of 1,315 m, the whole core is dominated by hemipelagic sediments and is of 20.7 m in length. Samples for AMS <sup>14</sup>C dating were selected at roughly 2 ka interval with a total of 16 samples. The ages show a continuously younging-upward trend with bottom of this core around 35,000 years BP. Samples for high-resolution oxygen isotope measurements were selected at a nominal 500-year age interval. The difference in δ<sup>18</sup>O between <em>G. ruber</em> (mixed layer dwelling species) and <em>N. dutertrei</em> (thermocline dwelling species) is used to reconstruct the upper ocean stratification with large difference indicating significant ocean stratification and vice versa. The results show moderate upper ocean stratification during 35-24 ka, and it became less stratified during the Last Glacial Maximum (LGM, 23-19 ka). During the deglacial stage, the stratification gradually became stronger until the early Holocene (12-9 ka), and it has kept strong upper-ocean stratification since 9 ka. Literature has documented less rainfall intensity during the LGM and heavy rainfall during the Holocene in southern Taiwan. We interpret the upper-ocean stratification in the NE South China Sea near Taiwan is linked to the amount of freshwater inputs from Taiwan. Less Taiwan freshwater input during the LGM led to a weak stratified upper ocean and a large amount of freshwater input from Taiwan led to a strong upper-ocean stratification during the Holocene.</p>

scholarly journals An assessment of the functional variability of selected coastal ecosystems in the context of local environmental changes

2009 ◽  
Vol 66 (7) ◽  
pp. 1520-1527 ◽  
Author(s):  
Dan Baird
Keyword(s):  
Environmental Changes ◽  
System Organization ◽  
Coastal Ecosystems ◽  
System Throughput ◽  
Total System ◽  
Nutrient Input ◽  
Run Off ◽  
Carbon Recycling ◽  
Physical Changes ◽  
Selection Of

Abstract Baird, D. (2009) An assessment of the functional variability of selected coastal ecosystems in the context of local environmental changes. – ICES Journal of Marine Science, 66: 1520–1527. The functioning of coastal ecosystems is greatly dependent on a wide variety of external pulses (e.g. tides, freshwater influx, seasonal trends in temperature, nutrient input, etc.). Assessments of the effect of a selection of environmental characteristics driven by natural and/or anthropogenic forces on ecosystem function are given using selected ecosystem properties, such as total system throughput, system organization, productivity, recycling, and trophic efficiency, derived from ecological network analysis (ENA) of several coastal ecosystems on monthly, intra-seasonal, seasonal, and interdecadal scales. Each ecosystem was modelled depicting data of standing stocks, the flows between the constituent living and non-living components in the system, exports, and imports. Results from ENA revealed considerable differences of the same property (or properties) resulting from physical changes (e.g. temperature, salinity, oxygen, rate of freshwater inflow) over time. A small temperature increase in a Florida seagrass bed, for example, resulted in increases in system throughput, the P/B ratio, and in the rate of carbon recycling, but also in a significant decrease in system organization. The effect of seasonal increases in water temperature and of measured decrease/increase in river run-off to a few selected estuaries is discussed using ENA.

Southward shift of the Intertropical Convergence Zone due to Northern Hemisphere cooling at the Oligocene-Miocene boundary

Geology ◽  
2014 ◽  
Vol 42 (8) ◽  
pp. 667-670 ◽  
Author(s):  
K. Hyeong ◽  
J. Lee ◽  
I. Seo ◽  
M. J. Lee ◽  
C. M. Yoo ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Intertropical Convergence Zone ◽  
Convergence Zone ◽  
Southward Shift

scholarly journals Preliminary results of high resolution paleoceanography and paleoclimatology during sapropel S1 deposition (South Limnos Basin, North Aegean Sea).

2016 ◽  
Vol 47 (1) ◽  
pp. 194
Author(s):  
S. Kostopoulou ◽  
M. B. Triantaphyllou ◽  
M. D. Dimiza ◽  
A. Gogou ◽  
I. Bouloubassi ◽  
...  
Keyword(s):  
High Resolution ◽  
Primary Productivity ◽  
Organic Material ◽  
Planktonic Foraminifera ◽  
Aegean Sea ◽  
Freshwater Input ◽  
Gravity Core ◽  
Preliminary Results ◽  
North Aegean ◽  
North Aegean Sea

The paleoenviromental conditions during the depositional interval of sapropel S1 in the northeastern Aegean (gravity core M-4, length 2.53 m; south Limnos basin) are studied based on quantitative micropaleontological (benthic and planktonic foraminifera) and geochemical (OC, δ13Corg) analyses. Special feature of core M-4 is the thickness of S1 layer (96 cm). Our study points that sapropelic layer S1a has been deposited in more dysoxic and warmer conditions in respect to S1b. Both primary productivity and preservation of organic material are more intense during the lower part of S1. An interruption of the sapropelic conditions at 8.0 Ka BP which is mainly characterized by the increase of agglutinated foraminiferal forms confirms both higher oxygen bottom conditions and freshwater input.

scholarly journals Climate Change in Areas of the Gulf of Mexico With High Freshwater Input – A Review of Impacts and Potential Mitigation

2019 ◽  
Vol 1 (1) ◽  
pp. 87-108
Author(s):  
J.W. Day ◽  
A.L. Lara Dominguez ◽  
J. Herrera-Silveira ◽  
G. Paul Kemp
Keyword(s):  
Climate Change ◽  
Gulf Of Mexico ◽  
Mississippi River ◽  
Coastal Wetlands ◽  
Water Discharge ◽  
Climate Change Impacts ◽  
Coastal Ecosystems ◽  
Freshwater Discharge ◽  
Freshwater Input ◽  
The North

The Gulf of Mexico currently spans the transition from tropical to temperate coastal ecosystems but this is changing as the northern Gulf undergoes tropicalization and the entire Gulf will become tropical in this century. The objective of this paper was to review information on climate change impacts on coastal ecosystems with high freshwater input for the Gulf of Mexico and review mitigation measures for dealing with climate change. There are two high freshwater discharge areas, one surrounding the Mississippi River in the north central Gulf and one in the southern Gulf, which is associated with the Grijalva-Usumacinta River and adjacent rivers and ground water discharge from the Yucatan Peninsula. Both of these areas are characterized by extensive coastal wetlands, and in the southern Gulf, submerged aquatic vegetation. These coastal ecosystems support important natural resources, have high petroleum production, and important maritime trade. Climate change will impact both of these areas strongly. Sea level is projected to increase by a meter or more by 2100 and there will be more strong hurricanes that will be larger, have more intense rainfall, will move slower, and the rate of intensification will increase. In the north, peak Mississippi River discharge is projected to increase by 10 to 60%. In the southern Gulf, it is projected that precipitation and freshwater discharge will decrease associated with the Mesoamerican climate hotspot. Coastal management to accommodate climate change should mimic ecosystem functioning. Specific actions include protection of natural areas, full use of freshwater and sediment resources, maintain con-nections between freshwater input and coastal systems, allow inland migration of coastal wetlands, and careful management of land use changes. Keywords: Gulf of Mexico, climate change impacts, coastal ecossytems.

Zooplankton Biomass in the Southern Gulf of St. Lawrence: Spatial Patterns and the Influence of Freshwater Runoff

1994 ◽  
Vol 51 (3) ◽  
pp. 617-635 ◽  
Author(s):  
Yves De Lafontaine
Keyword(s):  
Large Scale ◽  
Salinity Gradient ◽  
Distribution Patterns ◽  
Zooplankton Biomass ◽  
Freshwater Input ◽  
Entire Area ◽  
Freshwater Runoff ◽  
Coastal Shelf ◽  
Runoff Variability

The role of advection of freshwater input in Zooplankton distribution was evaluated from 16 surveys carried out in the southern Gulf of St. Lawrence during 1967–71. Biomass was structured according to two main patterns: large-scale gradients (> 150 km) over the entire area and mesoscafe (≈25 km) patches. Patterns exhibited seasonal and interannual variability without any sign of recurrence through time, unlike the spatial structure of surface water temperature and salinity which was typical of large-scale dispersion gradients resulting from the seasonal input of freshwater into the area. In most cases, overall distribution patterns of biomass and hydrographic variables were not significantly correlated, indicating that biomass patterns in the southern Gulf were not related to water mass characteristics and advection of freshwater runoff over the entire area. Although mesoscale patchiness was unrelated to hydrographic processes, patch size (≈25 km) was similar to estimates obtained for the northern Gulf and for other coastal shelf areas. Large-scale gradients in biomass may correspond to species changes in relation to the salinity gradient and/or topography and bathymetric features. I conclude that biomass alone is not an adequate predictor for monitoring changes and variability of Zooplankton in response to runoff variability.

Ultrastructure of Some Planktonic Formainifera

1974 ◽  
Vol 32 ◽  
pp. 190-191
Author(s):  
William H. Zucker
Keyword(s):  
Cell Biology ◽  
Water Mass ◽  
Planktonic Foraminifera ◽  
Uranyl Acetate ◽  
Ethanol Dehydration ◽  
Globigerinoides Ruber ◽  
Light Microscope Level ◽  
Globigerina Bulloides ◽  
Glutaraldehyde Solution ◽  
Diamond Knife

Planktonic foraminifera are widely-distributed and abundant zooplankters. They are significant as water mass indicators and provide evidence of paleotemperatures and events which occurred during Pleistocene glaciation. In spite of their ecological and paleological significance, little is known of their cell biology. There are few cytological studies of these organisms at the light microscope level and some recent reports of their ultrastructure.Specimens of Globigerinoides ruber, Globigerina bulloides, Globigerinoides conglobatus and Globigerinita glutinata were collected in Bermuda waters and fixed in a cold cacodylate-buffered 6% glutaraldehyde solution for two hours. They were then rinsed, post-fixed in Palade's fluid, rinsed again and stained with uranyl acetate. This was followed by graded ethanol dehydration, during which they were identified and picked clean of debris. The specimens were finally embedded in Epon 812 by placing each organism in a separate BEEM capsule. After sectioning with a diamond knife, stained sections were viewed in a Philips 200 electron microscope.

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