Microstratigraphic study of meristic variation in an Eocene fish from a 10 000-year varved interval at Horsefly, British Columbia

1999 ◽  
Vol 36 (12) ◽  
pp. 2059-2072 ◽  
Author(s):  
Douglas G Barton ◽  
Mark VH Wilson
Keyword(s):  
British Columbia ◽  
Environmental Change ◽  
Temporal Variation ◽  
Temporal Resolution ◽  
Environmental Changes ◽  
Middle Eocene ◽  
Fish Population ◽  
Fin Rays ◽  
Meristic Variation ◽  
Reference Section

Varved, lacustrine rocks of the Middle Eocene Horsefly deposits in British Columbia are ideal for microstratigraphic studies. Temporal resolution in such varved deposits can theoretically be as small as a year. In the Horsefly beds, specimens can be assigned precisely to their position in the stratigraphic section by comparing the laminations enclosing the fossils with those of a reference section. Each fossil can thus be assigned to a relative year of death. Some 700 specimens of the catostomid fish Amyzon aggregatum from the 10 000-year "H3" varved interval are examined for meristic variation. Very few of the meristic variables are significantly correlated with each other. Meristic series that are the last to develop ontogenetically are also the most phenotypically variable. In the studied interval, meristic variation has a strong temporal component, particularly in the case of fin rays and in the ratio between precaudal and caudal vertebral counts. Much, but not all, of this temporal variation occurs in conjunction with environmental changes in the lake as estimated by taphonomy and is consistent with some combination of ecophenotypic and (or) evolutionary responses of the fish population to the environmental change.

Eohiodon woodruffi n. sp. (Teleostei, Hiodontidae), from the Middle Eocene Klondike Mountain Formation near Republic, Washington

1978 ◽  
Vol 15 (5) ◽  
pp. 679-686 ◽  
Author(s):  
Mark V. H. Wilson
Keyword(s):  
British Columbia ◽  
New Species ◽  
Middle Eocene ◽  
Fin Rays ◽  
Middle Member

The new species Eohiodon woodruffi is the second known species of the fossil hiodontid genus Eohiodon. It occurs in Middle Eocene freshwater tuffaceous shales of the lower Tom Thumb Tuff Member and the Middle Member of the Klondike Mountain Formation, near Republic, Washington. The new species differs from Eohiodon rosei in having more anal fin rays and in being deeper bodied. Eohiodon woodruffi also occurs with Eohiodon rosei in Eocene sediments near Horsefly, British Columbia.

Vegetative Growth of Eorhiza arnoldii Robison and Person from the Middle Eocene Princeton Chert Locality of British Columbia

1994 ◽  
Vol 155 (5) ◽  
pp. 606-616 ◽  
Author(s):  
Ruth A. Stockey ◽  
Kathleen B. Pigg
Keyword(s):  
British Columbia ◽  
Vegetative Growth ◽  
Middle Eocene

Further observations on Paleorosa similkameenensis (Rosaceae) from the Middle Eocene Princeton chert of British Columbia, Canada

1993 ◽  
Vol 78 (3-4) ◽  
pp. 277-291 ◽  
Author(s):  
Sergio R.S. Cevallos-Ferriz ◽  
Diane M. Erwin ◽  
Ruth A. Stockey
Keyword(s):  
British Columbia ◽  
Middle Eocene

Fossil Mosses from the Bisaccate Zone of the Mid-Eocene Allenby Formation, British Columbia

1974 ◽  
Vol 11 (3) ◽  
pp. 409-421 ◽  
Author(s):  
Marian Kuc
Keyword(s):  
British Columbia ◽  
Middle Eocene ◽  
Plant Tissues ◽  
Plant Remains ◽  
Lake Bottom ◽  
White Colour

New fossil taxa (Ditrichites fylesi, Muscites maycocki, M. ritchiei, Palaeohypnum jovet-asti and P. steerei); unnamed moss and moss-like fossils, detrital fragments of various plant tissues, and paleobotanical evidence of the bisaccate zone are described from the Middle Eocene Allenby Formation near Princeton, British Columbia. These remains occur in laminated, tuffaceous, silty and pyroclastic shale, deposited under lacustrine conditions.Detailed examination of the various laminae indicates that beds of white colour and composed of coarser silt grains are poor in fossils and could be related to periods of decreasing bioproduction; less silty and darker coloured beds are rich in macro- and microfossils and could be related to periods of extensive bioproduction. The rock features, lamination, and distribution of macrofossils indicate the slow and undisturbed accumulation of plant remains on a lake bottom.

Eocene age for Ag–Pb–Zn–Au vein and replacement deposits of the Kokanee Range, southeastern British Columbia

1992 ◽  
Vol 29 (1) ◽  
pp. 3-14 ◽  
Author(s):  
G. Beaudoin ◽  
J. C. Roddick ◽  
D. F. Sangster
Keyword(s):  
British Columbia ◽  
Middle Jurassic ◽  
Middle Eocene ◽  
Hanging Wall ◽  
Spatial Association ◽  
High Heat ◽  
Time Interval ◽  
Genetic Link ◽  
Metasedimentary Rocks ◽  
Magmatic Event

The Ag–Pb–Zn–Au vein and replacement deposits of the Kokanee Range, southeastern British Columbia, are hosted by the Middle Jurassic Nelson batholith and surrounding Cambrian to Triassic metasedimentary rocks in the hanging wall of the transcrustal Slocan Lake Fault, Field relations indicate that mineralization is younger than the Nelson batholith and a Middle Jurassic foliation in the Ainsworth area but coeval or older than Eocene unroofing of the Valhalla metamorphic core complex in the footwall of the Slocan Lake Fault. Lamprophyre and gabbro dykes are broadly coeval with mineralization and have biotite and hornblende K–Ar ages defining a short-lived Middle Eocene alkaline magmatic event between 52 and 40 Ma. An older, Early Cretaceous alkaline magmatic event (141 – 129 Ma) is possible but incompletely documented.K–Ar and step-heating 40Ar/39Ar analyses on hydrothermal vein and alteration muscovite indicate that hydrothermal fluids were precipitating vein and replacement deposits 58–59 Ma ago. Crosscutting relationships with lamprophyre dykes indicate the Kokanee Range hydrothermal system lasted for more than 15 Ma. Eocene crustal extension resulted in a high heat flow and structures which were probably responsible for hydrothermal fluid movement and flow paths.A 100 Ma time interval is documented between batholith emplacement and spatially associated mineralization, ruling out any genetic link between the two. Similar large age differences between granite intrusion and peripheral mineralization have recently been documented for two world-sea le Ag–Pb–Zn vein districts, which suggest that spatial association between granite and Ag–Pb–Zn mineralization is not sufficient to infer a genetic link.

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 Getting to green: Niche-driven or government-led entrepreneurship and sustainability in the wine industry

2011 ◽  
Vol 14 (1) ◽  
pp. 47-60 ◽  
Author(s):  
Lauretta Frederking
Keyword(s):  
British Columbia ◽  
Environmental Change ◽  
Environmental Values ◽  
Wine Industry ◽  
Niche Model ◽  
The Government ◽  
Sustainability Movement

Through the framework of Michael Porterʼs five forces, this article compares sustainability in the Oregon and British Columbia wine industries. After describing the contrasting characteristics of the green niche model and the government-led model of environmental change, the article analyzes the emerging challenges for each type of change.The distinct sources for profitability and future innovation suggests diversity within the sustainability movement and two very different processes of translating environmental values into entrepreneurial practice.

Spatial and temporal variation in abundance, group size and behaviour of bottlenose dolphins in the Florida coastal Everglades

2017 ◽  
Vol 98 (5) ◽  
pp. 1097-1107 ◽  
Author(s):  
Robin E. Sarabia ◽  
Michael R. Heithaus ◽  
Jeremy J. Kiszka
Keyword(s):  
Temporal Variation ◽  
Environmental Changes ◽  
Bottlenose Dolphins ◽  
Ecosystem Restoration ◽  
Spatial And Temporal Variation ◽  
Coastal Oceans ◽  
Inland Bays ◽  
Long Time ◽  
Time Periods ◽  
Ecological Importance

Bottlenose dolphins (Tursiops truncatus) are abundant in many coastal ecosystems, including the coastal Everglades. Understanding spatial and temporal variation in their abundance and group sizes is important for estimating their potential ecological importance and predicting how environmental changes (e.g. ecosystem restoration) might impact their populations. From August 2010 to June 2012, we completed a total of 67 belt transects covering a total of 2650 linear km and an area of 1232 km2. Dolphin densities varied spatially and temporally. The highest densities of dolphins were found in coastal oceans and inland bays and were lowest in rivers. Use of rivers, however, increased during the dry season while densities in other habitats remained similar across seasons. Dolphins appeared to prefer portions of bays close to mangrove-covered islands over open waters. A resighting rate of 63.6% of individuals across the 2-year study suggests that at least a portion of the population is probably resident within study regions over long time periods. The largest groups (mean 6.28, range 1–31) were found in open waters and bays despite apparently low predation pressure. Indeed, shark bite scars – likely the result of unsuccessful predation attempts – were conclusively observed on only 1% of individuals. Although further studies are warranted, the high densities of dolphins suggest that they are an important upper trophic level predator in the coastal Everglades, but their ecological importance probably varies in space and time.

scholarly journals Expressions of climate perturbations in western Ugandan crater lake sediment records during the last 1000 yr

2013 ◽  
Vol 9 (5) ◽  
pp. 5183-5226 ◽  
Author(s):  
K. Mills ◽  
D. B. Ryves ◽  
N. J. Anderson ◽  
C. L. Bryant ◽  
J. J. Tyler
Keyword(s):  
Environmental Change ◽  
East Africa ◽  
Environmental Changes ◽  
Sediment Cores ◽  
Ice Age ◽  
Ecosystem Response ◽  
Large Lakes ◽  
Crater Lakes ◽  
Continental Scale ◽  
Western Uganda

Abstract. Equatorial East Africa has a complex, regional patchwork of climate regimes, with multiple interacting drivers. Recent studies have focussed on large lakes and reveal signals that are smoothed in both space and time, and, whilst useful at a continental scale, are of less relevance when understanding short-term, abrupt or immediate impacts of climate and environmental changes. Smaller-scale studies have highlighted spatial complexity and regional heterogeneity of tropical palaeoenvironments in terms of responses to climatic forcing (e.g. the Little Ice Age [LIA]) and questions remain over the spatial extent and synchroneity of climatic changes seen in East African records. Sediment cores from paired crater lakes in western Uganda were examined to assess ecosystem response to long-term climate and environmental change as well as testing responses to multiple drivers using redundancy analysis. These archives provide annual to sub-decadal records of environmental change. The records from the two lakes demonstrate an individualistic response to external (e.g. climatic) drivers, however, some of the broader patterns observed across East Africa suggest that the lakes are indeed sensitive to climatic perturbations such as a dry Mediaeval Climate Anomaly (MCA; 1000–1200 AD) and a relatively drier climate during the main phase of the LIA (1500–1800 AD); though lake levels in western Uganda do fluctuate. The relationship of Ugandan lakes to regional climate drivers breaks down c. 1800 AD, when major changes in the ecosystems appear to be a response to sediment and nutrient influxes as a result of increasing cultural impacts within the lake catchments. The data highlight the complexity of individual lake response to climate forcing, indicating shifting drivers through time. This research also highlights the importance of using multi-lake studies within a landscape to allow for rigorous testing of climate reconstructions, forcing and ecosystem response.

Future Environments of South America

2007 ◽  
Author(s):  
Thomas T. Veblen ◽  
Kenneth R. Young
Keyword(s):  
South America ◽  
Environmental Change ◽  
Environmental Changes ◽  
Human Impacts ◽  
Southern Oscillation ◽  
Physical Geography ◽  
Tierra Del Fuego ◽  
South American ◽  
Policy Options ◽  
Natural Processes

An important goal of this book has been to provide a comprehensive understanding of the physical geography and landscape origins of South America as important background to assessing the probabilities and consequences of future environmental changes. Such background is essential to informed discussions of environmental management and the development of policy options designed to prepare local, national, and international societies for future changes. A unifying theme of this book has been the elucidation of how natural processes and human activities have interacted in the distant and recent past to create the modern landscapes of the continent. This retrospective appreciation of how the current landscapes have been shaped by nature and humans will guide our discussion of possible future trajectories of South American environments. There is abundant evidence from all regions of South America, from Tierra del Fuego to the Isthmus of Panama, that environmental change, not stasis, has been the norm. Given that fact, the history, timing, and recurrence intervals of this dynamism are all crucial pieces of information. The antiquity and widespread distribution of changes associated with the indigenous population are now well established. Rates and intensities of changes related to indigenous activities varied widely, but even in regions formerly believed to have experienced little or no pre-European impacts we now recognize the effects of early humans on features such as soils and vegetation. Colonization by Europeans mainly during the sixteenth century modified or in some cases replaced indigenous land-use practices and initiated changes that have continued to the present. Complementing these broad historical treatments of human impacts, other chapters have examined in detail the environmental impacts of agriculture (chapter 18) and urbanism (chapter 20), and the disruptions associated with El Niño–Southern Oscillation events. The goal of this final synthesis is to identify the major drivers of change and to discuss briefly their likely impacts on South American environments and resources in the near and medium-term future. Our intent is not to make or defend predictions, but rather to identify broad causes and specific drivers of environmental change to inform discussions of policy options for mitigating undesirable changes and to facilitate potential societal adaptations to them.

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