scholarly journals A conservation palaeobiological perspective on Chesapeake Bay oysters

2019 ◽  
Vol 374 (1788) ◽  
pp. 20190209 ◽  
Author(s):  
Rowan Lockwood ◽  
Roger Mann
Keyword(s):  
Chesapeake Bay ◽  
Fossil Record ◽  
Ecosystem Engineer ◽  
Oyster Shell ◽  
Eastern Oyster ◽  
Vital Role ◽  
The Past ◽  
Region Data ◽  
Order Of Magnitude ◽  
Fossil Data

The eastern oyster plays a vital role in estuarine habitats, acting as an ecosystem engineer and improving water quality. Populations of Chesapeake Bay oysters have declined precipitously in recent decades. The fossil record, which preserves 500 000 years of once-thriving reefs, provides a unique opportunity to study pristine reefs to establish a possible baseline for mitigation. For this study, over 900 fossil oysters were examined from three Pleistocene localities in the Chesapeake region. Data on oyster shell lengths, lifespans and population density were assessed. Comparisons to modern Crassostrea virginica , sampled from monitoring surveys of similar environments, reveal that fossil oysters were significantly larger, longer-lived and more abundant than modern oysters from polyhaline salinity zones. This pattern results from the preferential harvesting of larger, reproductively more active females from the modern population. These fossil data, combined with modern estimates of age-based fecundity and mortality, make it possible to estimate ecosystem services in these long-dead reefs, including filtering capacity, which was an order of magnitude greater in the past than today. Conservation palaeobiology can provide us with a picture of not just what the Chesapeake Bay looked like, but how it functioned, before humans. This article is part of a discussion meeting issue ‘The past is a foreign country: how much can the fossil record actually inform conservation?’

ORIGINATIONS AND EXTINCTIONS: ANALYSES OF FOSSIL DATA AND SIMULATIONS

2000 ◽  
Vol 11 (02) ◽  
pp. 277-285 ◽  
Author(s):  
TANE RAY ◽  
LEO MOSELEY ◽  
NAEEM JAN
Keyword(s):  
Fourier Transform ◽  
Frequency Dependence ◽  
Frequency Spectrum ◽  
Fossil Record ◽  
Trophic Levels ◽  
The Other ◽  
Simulation Data ◽  
The Past ◽  
Other Hand ◽  
Fossil Data

We analyse the fossil data of Benton1 with and without interpolation schemes. By Fourier transform analysis, we find a frequency dependence of the amplitude of 1/f for the various interpolation schemes used in the past. We illustrate that shuffling the interpolated data changes the spectra only slightly. On the other hand, an identical analysis performed on the raw (uninterpolated) fossil data gives a flat frequency spectrum. We conclude that the 1/f behavior is an artifact of the interpolation schemes. We next introduce a simulation of extinctions driven only by interactions between two trophic levels. Fourier transform analysis of the simulation data shows a frequency dependence of 1/f. When the data are grouped into a form resembling the fossil record the frequency dependence vanishes, giving a flat spectrum. Our simulation produces a frequency spectrum that agrees with the observed fossil record.

scholarly journals A multiscale view of the Phanerozoic fossil record reveals the three major biotic transitions

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Alexis Rojas ◽  
Joaquin Calatayud ◽  
Michał Kowalewski ◽  
Magnus Neuman ◽  
Martin Rosvall
Keyword(s):  
Fossil Record ◽  
Large Scale ◽  
Multilayer Network ◽  
Biotic Crisis ◽  
The Past ◽  
Empirical Estimates ◽  
Multiscale Dynamics ◽  
Ecological Changes ◽  
Fossil Data

AbstractThe hypothesis of the Great Evolutionary Faunas is a foundational concept of macroevolutionary research postulating that three global mega-assemblages have dominated Phanerozoic oceans following abrupt biotic transitions. Empirical estimates of this large-scale pattern depend on several methodological decisions and are based on approaches unable to capture multiscale dynamics of the underlying Earth-Life System. Combining a multilayer network representation of fossil data with a multilevel clustering that eliminates the subjectivity inherent to distance-based approaches, we demonstrate that Phanerozoic oceans sequentially harbored four global benthic mega-assemblages. Shifts in dominance patterns among these global marine mega-assemblages were abrupt (end-Cambrian 494 Ma; end-Permian 252 Ma) or protracted (mid-Cretaceous 129 Ma), and represent the three major biotic transitions in Earth’s history. Our findings suggest that gradual ecological changes associated with the Mesozoic Marine Revolution triggered a protracted biotic transition comparable in magnitude to the end-Permian transition initiated by the most severe biotic crisis of the past 500 million years. Overall, our study supports the notion that both long-term ecological changes and major geological events have played crucial roles in shaping the mega-assemblages that dominated Phanerozoic oceans.

Testing the time axis of phylogenies

1995 ◽  
Vol 349 (1327) ◽  
pp. 5-10 ◽  
Keyword(s):  
Phylogenetic Analysis ◽  
Fossil Record ◽  
Direct Evidence ◽  
Phylogeny Reconstruction ◽  
Time Axis ◽  
Historical Events ◽  
Subsequent Evolution ◽  
The Past ◽  
Fossil Data

Fossils are not perfect materials for phylogenetic analysis because of problems of missing characters and missing taxa. However, fossils have three major advantages: (1) they give the only direct evidence of the order of acquisition of characters, (2) they frequently present character combinations not found in modern forms, and (3) they may allow the coding of characters that have been overwritten by subsequent evolution within a clade. There are three independent sources of evidence about sequences of historical events in evolution - morphological, molecular and stratigraphic - and these may be mutually cross- tested. Tests of the quality of the fossil record against morphological cladistic data show that (1) age and clade data on branching sequences generally agree, (2) knowledge of the fossil record has improved by 5% over the past 26 years of research, and (3) the fossil record of continental vertebrates is as good as that of (marine) echinoderms. Hence, systematists and evolutionary biologists may use fossil data with confidence in phylogeny reconstruction and to calibrate the time axis of phylogenies.

Dose-Related Toxicity of Copper and Cadmium in Striped Bass Larvae from the Chesapeake Bay: Field Considerations

1988 ◽  
Vol 20 (6-7) ◽  
pp. 39-48 ◽  
Author(s):  
David A. Wright
Keyword(s):  
Chesapeake Bay ◽  
Striped Bass ◽  
Toxic Metal ◽  
Published Data ◽  
Metal Concentrations ◽  
Frequency Distributions ◽  
Order Of Magnitude ◽  
Toxic Concentrations ◽  
And Control ◽  
Spawning Tributaries

Copper and cadmium monitoring in Chesapeake Bay sediments indicates that metal contamination exists in nursery areas for striped bass (Moronesaxatilis), which has been in serious decline over the last 17 years. Whole water metal concentrations in one spawning river were within an order of magnitude of published acutely toxic concentrations. Larval striped bass were exposed in the laboratory to copper and cadmium concentrations which were acutely toxic over a 96h period (24 and 19 µg L−1, respectively), and to sub-lethal concentrations of these metals over a three week period. Larvae from acutely toxic metal treatments, sub-lethal metal concentrations and control tanks were analyzed for cadmium and copper and the frequency distribution of metal body burdens was compared with field data. The distribution of copper concentrations in laboratory-exposed larvae was completely within the range of field specimens, and there was considerable overlap in cadmium frequency distributions from laboratory and field larvae. These results together with other published data suggest that environmental metal concentrations in some spawning tributaries of the Chesapeake Bay may pose a threat to striped bass, and the suggestion is made that greater efforts should be made to link laboratory and field toxicological data.

HURRICANE FREQUENCY NEAR CHESAPEAKE BAY DURING THE PAST MILLENNIUM

2019 ◽  
Author(s):  
Michael Toomey ◽  
◽  
Nicole D'Entremont ◽  
Emma Armstrong ◽  
Thomas Cronin ◽  
...  
Keyword(s):  
Chesapeake Bay ◽  
The Past ◽  
Past Millennium

scholarly journals Spatial population dynamics of eastern oyster in the Chesapeake Bay, Maryland

2021 ◽  
Vol 237 ◽  
pp. 105854
Author(s):  
Marvin M. Mace ◽  
Kathryn L. Doering ◽  
Michael J. Wilberg ◽  
Amy Larimer ◽  
Frank Marenghi ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Chesapeake Bay ◽  
Eastern Oyster ◽  
Spatial Population ◽  
Spatial Population Dynamics

scholarly journals Use of PRP, PRF and CGF in Periodontal Regeneration and Facial Rejuvenation—A Narrative Review

Biology ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 317
Author(s):  
Eitan Mijiritsky ◽  
Haya Drora Assaf ◽  
Oren Peleg ◽  
Maayan Shacham ◽  
Loredana Cerroni ◽  
...  
Keyword(s):  
Growth Factors ◽  
Platelet Rich Plasma ◽  
Periodontal Regeneration ◽  
Clinical Work ◽  
Gingival Recession ◽  
Vital Role ◽  
Facial Rejuvenation ◽  
Cochrane Library ◽  
The Past ◽  
Autologous Platelet

Growth factors (GFs) play a vital role in cell proliferation, migration, differentiation and angiogenesis. Autologous platelet concentrates (APCs) which contain high levels of GFs make them especially suitable for periodontal regeneration and facial rejuvenation. The main generations of APCs presented are platelet-rich plasma (PRP), platelet-rich fibrin (PRF) and concentrated growth factor (CGF) techniques. The purpose of this review is to provide the clinician with an overview of APCs’ evolution over the past decade in order to give reliable and useful information to be used in clinical work. This review summarizes the most interesting and novel articles published between 1997 and 2020. Electronic and manual searches were conducted in the following databases: Pubmed, Scopus, Cochrane Library and Embase. The following keywords were used: growth factors, VEGF, TGF-b1, PRP, PRF, CGF and periodontal regeneration and/or facial rejuvenation. A total of 73 articles were finally included. The review then addresses the uses of the three different techniques in the two disciplines, as well as the advantages and limitations of each technique. Overall, PRP is mainly used in cases of hard and soft tissue procedures, while PRF is used in gingival recession and the treatment of furcation and intrabony defects; CGF is mainly used in bone regeneration.

scholarly journals Effects of Infectious Diseases on Population Dynamics of Marine Organisms in Chesapeake Bay

2021 ◽  
Author(s):  
Jerelle A. Jesse ◽  
M. Victoria Agnew ◽  
Kohma Arai ◽  
C. Taylor Armstrong ◽  
Shannon M. Hood ◽  
...  
Keyword(s):  
Climate Change ◽  
Population Dynamics ◽  
Infectious Diseases ◽  
Chesapeake Bay ◽  
Eastern Oyster ◽  
Marine Organisms ◽  
Ecosystem Dynamics ◽  
Climate Change Effects ◽  
Pathogen Dynamics ◽  
Growth And Reproduction

AbstractDiseases are important drivers of population and ecosystem dynamics. This review synthesizes the effects of infectious diseases on the population dynamics of nine species of marine organisms in the Chesapeake Bay. Diseases generally caused increases in mortality and decreases in growth and reproduction. Effects of diseases on eastern oyster (Crassostrea virginica) appear to be low in the 2000s compared to effects in the 1980s–1990s. However, the effects of disease were not well monitored for most of the diseases in marine organisms of the Chesapeake Bay, and few studies considered effects on growth and reproduction. Climate change and other anthropogenic effects are expected to alter host-pathogen dynamics, with diseases of some species expected to worsen under predicted future conditions (e.g., increased temperature). Additional study of disease prevalence, drivers of disease, and effects on population dynamics could improve fisheries management and forecasting of climate change effects on marine organisms in the Chesapeake Bay.

scholarly journals A Response of Snow Cover to the Climate in the Northwest Himalaya (NWH) Using Satellite Products

2021 ◽  
Vol 13 (4) ◽  
pp. 655
Author(s):  
Animesh Choudhury ◽  
Avinash Chand Yadav ◽  
Stefania Bonafoni
Keyword(s):  
Snow Cover ◽  
Land Surface ◽  
Significant Negative Correlation ◽  
Shuttle Radar Topography Mission ◽  
Vital Role ◽  
Snow Cover Area ◽  
Study Region ◽  
Northwest Himalaya ◽  
The Past ◽  
Average Annual Temperature

The Himalayan region is one of the most crucial mountain systems across the globe, which has significant importance in terms of the largest depository of snow and glaciers for fresh water supply, river runoff, hydropower, rich biodiversity, climate, and many more socioeconomic developments. This region directly or indirectly affects millions of lives and their livelihoods but has been considered one of the most climatically sensitive parts of the world. This study investigates the spatiotemporal variation in maximum extent of snow cover area (SCA) and its response to temperature, precipitation, and elevation over the northwest Himalaya (NWH) during 2000–2019. The analysis uses Moderate Resolution Imaging Spectroradiometer (MODIS)/Terra 8-day composite snow Cover product (MOD10A2), MODIS/Terra/V6 daily land surface temperature product (MOD11A1), Climate Hazards Infrared Precipitation with Station data (CHIRPS) precipitation product, and Shuttle Radar Topography Mission (SRTM) DEM product for the investigation. Modified Mann-Kendall (mMK) test and Spearman’s correlation methods were employed to examine the trends and the interrelationships between SCA and climatic parameters. Results indicate a significant increasing trend in annual mean SCA (663.88 km2/year) between 2000 and 2019. The seasonal and monthly analyses were also carried out for the study region. The Zone-wise analysis showed that the lower Himalaya (184.5 km2/year) and the middle Himalaya (232.1 km2/year) revealed significant increasing mean annual SCA trends. In contrast, the upper Himalaya showed no trend during the study period over the NWH region. Statistically significant negative correlation (−0.81) was observed between annual SCA and temperature, whereas a nonsignificant positive correlation (0.47) existed between annual SCA and precipitation in the past 20 years. It was also noticed that the SCA variability over the past 20 years has mainly been driven by temperature, whereas the influence of precipitation has been limited. A decline in average annual temperature (−0.039 °C/year) and a rise in precipitation (24.56 mm/year) was detected over the region. The results indicate that climate plays a vital role in controlling the SCA over the NWH region. The maximum and minimum snow cover frequency (SCF) was observed during the winter (74.42%) and monsoon (46.01%) season, respectively, while the average SCF was recorded to be 59.11% during the study period. Of the SCA, 54.81% had a SCF above 60% and could be considered as the perennial snow. The elevation-based analysis showed that 84% of the upper Himalaya (UH) experienced perennial snow, while the seasonal snow mostly dominated over the lower Himalaya (LH) and the middle Himalaya (MH).

Did Ground Cover Change Over Geologic Time?

2000 ◽  
Vol 6 ◽  
pp. 171-182 ◽  
Author(s):  
Ben A. LePage ◽  
Hermann W. Pfefferkorn
Keyword(s):  
Fossil Record ◽  
Ground Cover ◽  
The Other ◽  
Detailed Account ◽  
Geologic Time ◽  
The Past ◽  
Other Hand ◽  
Plant Fossil

When one hears the term “ground cover,” one immediately thinks of “grasses.” This perception is so deep-seated that paleobotanists even have been overheard to proclaim that “there was no ground cover before grasses.” Today grasses are so predominant in many environments that this perception is perpetuated easily. On the other hand, it is difficult to imagine the absence or lack of ground cover prior to the mid-Tertiary. We tested the hypothesis that different forms of ground cover existed in the past against examples from the Recent and the fossil record (Table 1). The Recent data were obtained from a large number of sources including those in the ecological, horticultural, and microbiological literature. Other data were derived from our knowledge of Precambrian life, sedimentology and paleosols, and the plant fossil record, especially in situ floras and fossil “monocultures.” Some of the data are original observations, but many others are from the literature. A detailed account of these results will be presented elsewhere (Pfefferkorn and LePage, in preparation).

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