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SE US megalopolis.pdf
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Sea-level and salinity fluctuations during the Paleocene–Eocene thermal maximum in Arctic Spitsbergen
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Palaeoenvironmental manifestations of the Paleocene–Eocene thermal maximum (PETM; ~ 56 Ma) are relatively well documented in low- to mid-latitude settings and at high southern latitudes, but no documented high northern latitude sites record the entire hyperthermal event. We present high-resolution multi-proxy records from a PETM succession on Spitsbergen in the high Arctic (palaeolatitude ~75 °N). By comparing our results with those from Integrated Ocean Drilling Program Site 302-4A, we document regional palaeoenvironmental variations in the expression of the PETM, with evidence for major differences in basin- margin vegetation and water column oxygen depletion. Sedimentological, palynological and geochemical data demonstrate a pre-PETM sea level rise in Spitsbergen before the −4‰ δ13CTOC excursion, which culminated in maximum flooding during the peak of the event. The appearance of the dinoflagellate cyst Apectodinium before the onset of the carbon isotope excursion (CIE) corroborates that environmental change in the Arctic had begun prior to the CIE. Sedimentological and palynological evidence indicate that elevated terrestrial runoff resulted in water column stratification, providing further evidence for an intensification of the hydrological cycle during the PETM. Keywords:
abrupt/rapid climate change, PETM, paleoecology, sedimentology,
Spitsbergen, Arctic
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Image of the Search Organizations portlet for How to Add an Organization tutorial.
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Seasonal and diel patterns in the migrations of fishes between a river and a floodplain tributary
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The population behaviours associated with the migrations of fishes in lowland river ecosystems are amongst the most poorly-understood dispersal mechanisms of temperate freshwater organisms. This study evaluated the influence of four environmental variables (light levels, river discharge, water temperature and water velocity) on the timing, intensity and direction of fish movements between the River Avon (Hampshire, England) and a small floodplain tributary, Ibsley Brook, over a 12-month period. Using canonical correspondence analysis (CCA) to identify patterns of movement (by groups of species) and the relative strengths of explanatory variables in the data, the probability of fishes migrating between the river and tributary was determined using Bayesian modelling. The intensity and direction of fish movements between the river and tributary varied temporally, both on a diel and seasonal basis, and there were species- and age-specific patterns in behaviour. Diel movements appeared to be triggered by changes in light intensity and brook water velocity, whereas seasonal movements were mostly driven by changes in river discharge and water temperature, particularly those associated with floods. This study emphasises the importance of connectivity in river systems, as fishes migrated in all conditions, but especially during rapidly- rising discharge. ecosystem function; habitat connectivity; habitat fragmentation; habitat use; river discharge; water velocity
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Seasonal Neighbors: Residential Development Encroaches on Mule Deer Winter Range in Central Oregon
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Mule deer populations in central Oregon
are in decline, largely because of habitat
loss. Several factors are likely contributors.
Encroaching juniper and invasive
cheatgrass are replacing deer forage
with high nutritional value, such as bitterbrush
and sagebrush. Fire suppression
and reduced timber harvests mean fewer
acres of early successional forest, which
also offer forage opportunities. Human
development, including homes and roads,
is another factor. It is this one that scientists
with the Pacific Northwest Research
Station and their collaborators investigated
in a recent study.
As part of an interagency assessment of
the ecological effects of resort development
near Bend, Oregon, researchers
examined recent and potential development
rates and patterns and evaluated
their impact on mule deer winter range.
They found that residential development
in central Oregon is upsetting traditional
migratory patterns, reducing available
habitat, and possibly increasing stress
for mule deer. Many herds of mule deer
spend the summer in the Cascade Range
and move to lower elevations during the
winter. An increasing number of buildings,
vehicle traffic, fencing, and other
obstacles that accompany human land
use are making it difficult for mule deer
to access and use their winter habitat.
The study provides valuable information
for civic leaders, land use planners,
and land managers to use in weighing
the ecological impact of various land use
decisions in central Oregon.
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Seasons and Life Cycles
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A conceptual framework. This table is a guide to determining how individual species are responding to an extended growing
season by observing the duration of peak season. The life history of a species—from the onset of greening through the end of
senescence—is illustrated by the length of the solid lines. Each case represents a shift in the timing (columns) and duration
(rows) of one or more species in a hypothetical three-species community that includes an early-, mid-, and late-season species.
The growing season begins when the first species greens and ends when the last species senesces. The peak season (gray shaded
area) occurs when all species have started and none have completed their life history. Reproductive life history events likely
begin before the peak season and are completed before its end. The final row and column list changes that can be observed
through frequent observations of surface greenness.
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SECAS April 2024 Newsletter
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Logo sneak peek, Summit and Caribbean CoP reflections, Southeast CASC collaboration
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Southeast Conservation Adaptation Strategy (SECAS) Newsletter
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SECAS Newsletter October 2023
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SECAS October newsletter: 2023 Southeast Blueprint and SECAS goal report released, introducing the Midwest Blueprint
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SECAS Third Thursday Web Forum May 16th 10:00 am ET
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Web Forum on Thursday: Understanding coastal wetland change from multiple perspectives.
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