The Ecological Balance of Nature: Identifying Stasis and Growth in Late Cretaceous Planktonic Foraminifera from ODP Hole 690C (Weddell Sea)

2020 ◽  
Vol 50 (3) ◽  
pp. 313-317
Author(s):  
Martin A. Buzas ◽  
Lee-Ann C. Hayek ◽  
Brian T. Huber
Keyword(s):  
Species Richness ◽  
Late Cretaceous ◽  
Planktonic Foraminifera ◽  
Sampling Time ◽  
Weddell Sea ◽  
Species Evenness ◽  
Data Set ◽  
Balance Of Nature ◽  
Ecological Balance ◽  
Do So

ABSTRACT The ecological balance of nature is defined as an equilibrium between species richness (S) and species evenness (E) such that diversity (H) remains constant with time. Based on this definition, our approach identifies growth or decline in communities as perturbations from stasis and has successfully done so for benthic foraminiferal communities. Here, we examine whether this approach is appropriate for planktonic foraminifera. To do so, we utilized planktonic foraminiferal counts (39 samples, 66% recovery) from Maastrichtian sediments in the Weddell Sea from ODP Hole 690C. A total of 24 species were observed and both >63-µm and >150-µm fractions were counted. In the >63-µm fraction, nine communities were recognized while in the >150-µm fraction, there were 12. In both fractions at 70.45 Ma, a boundary was recognized and immediately after this boundary, a community in growth was identified. A trend of increasing diversity upcore was substantiated by regression on individual samples. For our purposes, the >150-µm fraction in this data set is sufficient to recognize community trends. The >150-µm fraction in Hole 690C has 82% of the sampling time in stasis and an average time per community is 0.85 Ma. The >63-µm fraction has 73% of the sampling time in stasis and an average time per community of 1.02 Ma.

The crucial boundaries in the development of the late cretaceous biota of plankton foraminifers in the southern part of the Indian ocean

2019 ◽  
Vol 59 (6) ◽  
pp. 1074-1085
Author(s):  
E. A. Sokolova
Keyword(s):  
Indian Ocean ◽  
Species Composition ◽  
Late Cretaceous ◽  
Upper Cretaceous ◽  
Planktonic Foraminifera ◽  
The Indian Ocean ◽  
Systematic Composition ◽  
Climatic Series

The article analyzes own data on the species composition of shells of planktonic foraminifera from the Upper Cretaceous sediments of the Indian Oceans, as well as from the sections of the offshore seas of Australia. The species of planktonic foraminifera are grouped and arranged in a climatic series. An analysis of the change in the systematic composition of foraminifers made it possible to distinguish periods of extreme and intermediate climatic states in the Late Cretaceous.

scholarly journals Increased mosquito abundance and species richness in Connecticut, United States 2001–2019

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tanya A. Petruff ◽  
Joseph R. McMillan ◽  
John J. Shepard ◽  
Theodore G. Andreadis ◽  
Philip M. Armstrong
Keyword(s):  
United States ◽  
Species Richness ◽  
Community Composition ◽  
Pathogen Transmission ◽  
Public Health Importance ◽  
Data Set ◽  
Mosquito Abundance ◽  
Total Species Richness ◽  
Multiple Species ◽  
Total Species

Abstract Historical declines in multiple insect taxa have been documented across the globe in relation to landscape-level changes in land use and climate. However, declines have either not been universally observed in all regions or examined for all species. Because mosquitoes are insects of public health importance, we analyzed a longitudinal mosquito surveillance data set from Connecticut (CT), United States (U.S.) from 2001 to 2019 to identify changes in mosquito community composition over time. We first analyzed annual site-level collections and metrics of mosquito community composition with generalized linear/additive mixed effects models; we also examined annual species-level collections using the same tools. We then examined correlations between statewide collections and weather variables as well as site-level collections and land cover classifications. We found evidence that the average trap night collection of mosquitoes has increased by ~ 60% and statewide species richness has increased by ~ 10% since 2001. Total species richness was highest in the southern portion of CT, likely due to the northward range expansion of multiple species within the Aedes, Anopheles, Culex, and Psorophora genera. How the expansion of mosquito populations in the northeast U.S. will alter mosquito-borne pathogen transmission in the region will require further investigation.

The Cretaceous and Paleocene pleurotomariid (Gastropoda: Vetigastropoda) fauna of Seymour Island, Antarctica

2009 ◽  
Vol 83 (5) ◽  
pp. 750-766 ◽  
Author(s):  
M. G. Harasewych ◽  
Anton Oleinik ◽  
William Zinsmeister
Keyword(s):  
Species Richness ◽  
New Zealand ◽  
South America ◽  
Late Cretaceous ◽  
Upper Cretaceous ◽  
Southern India ◽  
New Combination ◽  
The Family ◽  
The Status ◽  
Seymour Island

Leptomaria antipodensis and Leptomaria hickmanae are described from the Upper Cretaceous [Maastrichtian] Lopez de Bertodano Formation, Seymour Island, and represent the first Mesozoic records of the family Pleurotomariidae from Antarctica. Leptomaria stillwelli, L. seymourensis, Conotomaria sobralensis and C. bayeri, from the Paleocene [Danian], Sobral Formation, Seymour Island, are described as new. Leptomaria larseniana (Wilckens, 1911) new combination, also from the Sobral Formation, is redescribed based on better-preserved material. The limited diversity of the pleurotomariid fauna of Seymour Island is more similar to that of the Late Cretaceous faunas of Australia and New Zealand in terms of the number of genera and species, than to the older, more diverse faunas of South America, southern India, or northwestern Madagascar, supporting the status of the Weddelian Province as a distinct biogeographic unit. The increase in the species richness of this fauna during the Danian may be due to the final fragmentation of Gondwana during this period.

Crustal structure of the offshore Labrador margin into deep water from combined seismic reflection interpretation and gravity modeling

2020 ◽  
Vol 8 (2) ◽  
pp. SH1-SH17 ◽  
Author(s):  
J. Kim Welford ◽  
Deric Cameron ◽  
Erin Gillis ◽  
Victoria Mitchell ◽  
Richard Wright
Keyword(s):  
Late Cretaceous ◽  
Seismic Reflection ◽  
Gravity Data ◽  
Gravity Models ◽  
Gravity Modeling ◽  
Data Set ◽  
Shelf Slope ◽  
Gravity Forward Modeling ◽  
Thickness Variations ◽  
Similar Density

A regional long-offset 2D seismic reflection program undertaken along the Labrador margin of the Labrador Sea, Canada, and complemented by the acquisition of coincident gravity data, has provided an extensive data set with which to image and model the sparsely investigated outer shelf, slope, and deepwater regions. Previous interpretation of the seismic data revealed the extent of Mesozoic and Cenozoic basins and resulted in the remapping of the basin configuration for the entire margin. To map the synrift package and improve understanding of the geometry and extent of these basins, we have undertaken joint seismic interpretation and gravity forward modeling to reduce uncertainty in the identification of the prerift basement, which varies between Paleozoic shelfal deposits and Precambrian crystalline rocks, with similar density characteristics. With this iterative approach, we have obtained new depth to basement constraints and have deduced further constraints on crustal thickness variations along the Labrador margin. At the crustal scale, extreme localized crustal thinning has been revealed along the southern and central portions of the Labrador margin, whereas a broad, margin-parallel zone of thicker crust has been detected outboard of the continental shelf along the northern Labrador margin. Our final gravity models suggest that Late Cretaceous rift packages from further south extend along the entire Labrador margin and open the possibility of a Late Cretaceous source rock fairway extending into the Labrador basins.

War Making and the Building of State Capacity: Expanding the Bivariate Relationship

2017 ◽  
Author(s):  
Karen A. Rasler ◽  
William R. Thompson
Keyword(s):  
Gross Domestic Product ◽  
Empirical Analysis ◽  
State Capacity ◽  
Point Of View ◽  
Regime Type ◽  
Domestic Product ◽  
Data Set ◽  
Representative Data ◽  
The Relationship ◽  
Do So

A central cleavage in the war making-state making literature is between advocates of the notion that warfare has been the principal path to developing stronger states and critics who argue that the relationship no longer holds, especially in non-European contexts. It is suggested that the problem is simply one of theoretical specification. Increasingly intensive warfare, as manifested in European combat, made states stronger. Less intensive warfare, particularly common after 1945, is less likely to do so. Empirical analysis of a more representative data set on state capacity (revenues as a proportion of gross domestic product [GDP]), focusing on cases since 1870, strongly supports this point of view. The intensiveness of war is not the only factor at work—regime type and win/loss outcomes matter as well—but the relationship does not appear to be constrained by the level of development.

scholarly journals Diversity of Hoverfly (Diptera: Syrphidae) Communities in Different Habitat Types in Zanjan Province, Iran

ISRN Zoology ◽  
2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Masumeh Naderloo ◽  
Shahrokh Pashaei Rad
Keyword(s):  
Species Richness ◽  
Species Diversity ◽  
Rice Field ◽  
Diversity Analysis ◽  
Species Evenness ◽  
Habitat Types

The diversity of hoverfly communities was studied in four different habitat types (river side, woodland, fruit garden, and rice field) in the years of 2008 and 2009. Adult hoverflies were collected from different habitants in Zanjan province. A total of 31 species with 750 individuals of hoverflies were collected, among which Sphaerophoria scripta (Linnaeus), Eristalis arbustorum (Linnaeus) and Eristalis tenax (Linnaeus) were found to be the most abundant. Records from these four sites were used in the diversity analysis. The results indicated that river side and rice field showed the highest and lowest degree of species richness and species diversity. Also, river side and rice field showed the highest and lowest species evenness, respectively.

scholarly journals Labile Fe(II) concentrations in the Atlantic sector of the Southern Ocean along a transect from the subtropical domain to the Weddell Sea Gyre

2011 ◽  
Vol 8 (9) ◽  
pp. 2461-2479 ◽  
Author(s):  
G. Sarthou ◽  
E. Bucciarelli ◽  
F. Chever ◽  
S. P. Hansard ◽  
M. González-Dávila ◽  
...  
Keyword(s):  
Detection Limit ◽  
Southern Ocean ◽  
Weddell Sea ◽  
Surface Mixed Layer ◽  
Data Set ◽  
Atlantic Sector ◽  
Local Maxima ◽  
Oxidation Rates ◽  
The North ◽  
Deep Waters

Abstract. Labile Fe(II) distributions were investigated in the Sub-Tropical South Atlantic and the Southern Ocean during the BONUS-GoodHope cruise from 34 to 57° S (February–March 2008). Concentrations ranged from below the detection limit (0.009 nM) to values as high as 0.125 nM. In the surface mixed layer, labile Fe(II) concentrations were always higher than the detection limit, with values higher than 0.060 nM south of 47° S, representing between 39 % and 63 % of dissolved Fe (DFe). Apparent biological production of Fe(II) was evidenced. At intermediate depth, local maxima were observed, with the highest values in the Sub-Tropical domain at around 200 m, and represented more than 70 % of DFe. Remineralization processes were likely responsible for those sub-surface maxima. Below 1500 m, concentrations were close to or below the detection limit, except at two stations (at the vicinity of the Agulhas ridge and in the north of the Weddell Sea Gyre) where values remained as high as ~0.030–0.050 nM. Hydrothermal or sediment inputs may provide Fe(II) to these deep waters. Fe(II) half life times (t1/2) at 4°C were measured in the upper and deep waters and ranged from 2.9 to 11.3 min, and from 10.0 to 72.3 min, respectively. Measured values compared quite well in the upper waters with theoretical values from two published models, but not in the deep waters. This may be due to the lack of knowledge for some parameters in the models and/or to organic complexation of Fe(II) that impact its oxidation rates. This study helped to considerably increase the Fe(II) data set in the Ocean and to better understand the Fe redox cycle.

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