scholarly journals Temporal change in molluscan assemblages (bivalves and gastropods) of Frobisher Bay, Nunavut, Canada, over fifty years

2021 ◽  
Author(s):  
Erin C Herder ◽  
Alec Aitken ◽  
Evan Edinger
Keyword(s):  
Environmental Change ◽  
Diversity Indices ◽  
Ecological Impacts ◽  
Sediment Composition ◽  
Benthic Community Structure ◽  
Time Periods ◽  
Species Diversity Indices ◽  
Molluscan Assemblage ◽  
Long Term Studies

Long-term studies provide an effective way to assess the ecological impacts of decades-long environmental change in Arctic coastal benthic environments but are undertaken rarely in the Canadian Arctic. In light of this, historical datasets can be compared with modern samples to examine temporal differences in benthic community structure. Frobisher Bay, Nunavut provides a unique opportunity to use a historical census to examine the impacts that long-term environmental change have had on the marine benthos. Between 1967-1976 and in 2016, infaunal samples were collected in inner Frobisher Bay and were compared to determine how the molluscan assemblages have changed between the two time periods. Molluscan assemblages in two regions of inner Frobisher Bay (Iqaluit and Cairn Island) were examined to minimize sampling discrepancies between the two time periods. A long-term increase in mean annual air temperature and a decline in the length of the ice cover season were observed. Both regions exhibited some change in sediment composition and quality and in molluscan assemblage between the two time periods and species diversity indices also indicated some change between time periods. Both the 1967-1976 and 2016 molluscan datasets provide a baseline for future long-term studies in a changing Arctic.

The Gippsland Lakes: management challenges posed by long-term environmental change

2016 ◽  
Vol 67 (6) ◽  
pp. 721 ◽  
Author(s):  
Paul I. Boon ◽  
Perran Cook ◽  
Ryan Woodland
Keyword(s):  
Environmental Change ◽  
Storm Surges ◽  
Avicennia Marina ◽  
Ecological Impacts ◽  
Ramsar Convention ◽  
Late 20Th Century ◽  
Sea Levels ◽  
Marked Decline ◽  
Feasible Solutions

The Gippsland Lakes, listed under the Ramsar Convention in 1982, have undergone chronic salinisation since the cutting in 1889 of an artificial entrance to the ocean to improve navigational access, exacerbated in the mid–late 20th century by increasing regulation and extraction of water from inflowing rivers. Both developments have had substantial ecological impacts: a marked decline in the area of reed (Phragmites australis) beds; the loss of salt-intolerant submerged taxa such as Vallisneria australis, causing a shift to a phytoplankton-dominated system in Lake Wellington; and, nearer the entrance, an expansion in the area of seagrasses. Mangroves (Avicennia marina) first appeared in the late 1980s or early 1990s. Since 1986 recurring blooms of Nodularia spumigena have led to loss of recreational amenity and to the periodic closure of recreational and commercial fisheries. Changes to hydrological and salinity regimes have almost certainly shifted the contemporary fish community away from the pre-entrance state. Rises in eustatic sea levels and increases in storm surges will exacerbate the issue of chronic salinisation. Whether or not managers choose to intervene to prevent, or at least minimise, ongoing environmental change will inevitably prove controversial, and in some cases no socially or technologically feasible solutions may exist.

IMPACT OF THE ESSO BAYWAY OIL SPILL ON SALT MARSH MACRO FAUNA

1981 ◽  
Vol 1981 (1) ◽  
pp. 413-418
Author(s):  
Jeffry M. Neff ◽  
Mary Sue Sharp ◽  
Wayne L. McCulloch
Keyword(s):  
Penaeid Shrimp ◽  
Diversity Indices ◽  
Reference Station ◽  
Penaeus Setiferus ◽  
Marsh Sediments ◽  
Species Diversity Indices ◽  
Long Term Impact ◽  
Neches River ◽  
Spilled Oil

ABSTRACT On January 28, 1979, approximately 6,000 barrels of light Arabian crude oil was spilled into the lower Neches River near Port Neches, Texas. Much of the oil became stranded in the adjacent brackish-freshwater marsh, which is considered to be an important nursery area for postlarval penaeid shrimp. The purpose of this investigation was to assess the long-term impact of the spill on the macrofauna of the marsh. Petroleum hydrocarbon concentrations in marsh sediments were high (up to 7,000 mg/kg dry wt) at all but one unoiled reference station. Due to unusually high rainfall, salinity in the marsh was very low until September 1979, when it rose to 6 to 12 ‰ Macrocrustacean and fish populations were very similar at both oiled and reference stations in terms of species composition, number of species, and number of animals. Species diversity indices were similar at oiled and reference stations. Postlarval penaeid shrimp Penaeus setiferus did not enter the marsh until September when the salinity rose. They were equally abundant at oiled and reference stations. We conclude from this 9-month study that the spilled oil had little or no significant effect on the aquatic macrofauna, including penaeid shrimp, of the Neches River marshes. Environmental factors, salinity, and temperature, had a much greater effect on the marsh populations and obscured any effects that might be attributed to oil.

Black-legged kittiwakes as indicators of environmental change in the North Sea: Evidence from long-term studies

2007 ◽  
Vol 72 (1) ◽  
pp. 30-38 ◽  
Author(s):  
S. Wanless ◽  
M. Frederiksen ◽  
F. Daunt ◽  
B.E. Scott ◽  
M.P. Harris
Keyword(s):  
Environmental Change ◽  
North Sea ◽  
The North ◽  
The North Sea ◽  
Long Term Studies

scholarly journals Antagonistic effects of long- and short-term environmental variation on species coexistence

2021 ◽  
Vol 288 (1958) ◽  
pp. 20211491
Author(s):  
Ming Liu ◽  
Dustin R. Rubenstein ◽  
Siew Ann Cheong ◽  
Sheng-Feng Shen
Keyword(s):  
Species Coexistence ◽  
Environmental Changes ◽  
Environmental Variation ◽  
Ecological Impacts ◽  
Short Term ◽  
Term Variation ◽  
Environmental Fluctuations ◽  
Time Periods ◽  
The Impact

Assessing the impact of environmental fluctuations on species coexistence is critical for understanding biodiversity loss and the ecological impacts of climate change. Yet determining how properties like the intensity, frequency or duration of environmental fluctuations influence species coexistence remains challenging, presumably because previous studies have focused on indefinite coexistence. Here, we model the impact of environmental fluctuations at different temporal scales on species coexistence over a finite time period by employing the concepts of time-windowed averaging and performance curves to incorporate temporal niche differences within a stochastic Lotka–Volterra model. We discover that short- and long-term environmental variability has contrasting effects on transient species coexistence, such that short-term variation favours species coexistence, whereas long-term variation promotes competitive exclusion. This dichotomy occurs because small samples (e.g. environmental changes over long time periods) are more likely to show large deviations from the expected mean and are more difficult to predict than large samples (e.g. environmental changes over short time periods), as described in the central limit theorem. Consequently, we show that the complex set of relationships among environmental fluctuations and species coexistence found in previous studies can all be synthesized within a general framework by explicitly considering both long- and short-term environmental variation.

Implications of Long-Term Studies of Three Model Preschool Programs for Head Start

2008 ◽  
Author(s):  
Lawrence J. Schweinhart ◽  
Elena V. Malofeeva ◽  
Lawrence J. Schweinhart ◽  
Michelle M. Englund ◽  
Arthur J. Reynolds ◽  
...  
Keyword(s):  
Head Start ◽  
Preschool Programs ◽  
Long Term Studies

Primary varicose veins

Phlebologie ◽  
2010 ◽  
Vol 39 (03) ◽  
pp. 133-137
Author(s):  
H. Partsch
Keyword(s):  
Varicose Veins ◽  
Compression Therapy ◽  
Daily Practice ◽  
Clinical Severity ◽  
Compression Stockings ◽  
Primary Varicose Veins ◽  
The Cost ◽  
Convincing Data ◽  
Long Term Studies

SummaryBackground: Compression stockings are widely used in patients with varicose veins. Methods: Based on published literature three main points are discussed: 1. the rationale of compression therapy in primary varicose veins, 2. the prescription of compression stockings in daily practice, 3. studies required in the future. Results: The main objective of prescribing compression stockings for patients with varicose veins is to improve subjective leg complaints and to prevent swelling after sitting and standing. No convincing data are available concerning prevention of progression or of complications. In daily practice varicose veins are the most common indication to prescribe compression stockings. The compliance depends on the severity of the disorder and is rather poor in less severe stages. Long-term studies are needed to proof the cost-effectiveness of compression stockings concerning subjective symptoms and objective signs of varicose veins adjusted to their clinical severity. Conclusion: Compression stockings in primary varicose veins are able to improve leg complaints and to prevent swelling.

Diatoms and aquatic palynomorphs in the sediments of the Eurasian Arctic seas and their significance for paleooceanological investigations in the Arctic

2019 ◽  
pp. 246-251
Author(s):  
Yelena I. Polyakova ◽  
Yekaterina I. Novichkova ◽  
Tatiana S. Klyuvitkina ◽  
Elizaveta A. Agafonova ◽  
Irina M. Kryukova
Keyword(s):  
Bering Sea ◽  
Surface Sediments ◽  
Sea Water ◽  
The Arctic ◽  
Marginal Filter ◽  
Arctic Seas ◽  
Hydrological Parameters ◽  
The Arctic Ocean ◽  
Long Term Studies

Presented the results of long-term studies of diatoms and aquatic palynomorphs in surface sediments of the Arctic seas and the possibility of their use for the reconstructions of paleocirculation water masses, advection of Atlantic and Bering sea water into the Arctic ocean, changes in the river runoff to the seas, sedimentary processes in the marginal filter of the largest rivers, seasonal sea ice cover and other hydrological parameters.

Aspects of the Evolution of the Romanian Tourists’ Preferences Concerning the Domestic Tourist Destinations

2019 ◽  
Vol 10 (1) ◽  
pp. 21-28
Author(s):  
Aniela Bălăcescu ◽  
Radu Șerban Zaharia
Keyword(s):  
Logistic Model ◽  
Local Level ◽  
Medium Term ◽  
Tourist Destinations ◽  
Tourism Management ◽  
Production And Consumption ◽  
On Line ◽  
The One ◽  
Long Term Studies

Abstract Tourist services represent a category of services in which the inseparability of production and consumption, the inability to be storable, the immateriality, and last but not least non-durability, induces in tourism management a number of peculiarities and difficulties. Under these circumstances the development of medium-term strategies involves long-term studies regarding on the one hand the developments and characteristics of the demand, and on the other hand the tourist potential analysis at regional and local level. Although in the past 20 years there has been tremendous growth of on-line booking made by household users, the tour operators agencies as well as those with sales activity continue to offer the specific services for a large number of tourists, that number, in the case of domestic tourism, increased by 1.6 times in case of the tour operators and by 4.44 times in case of the agencies with sales activity. At the same time, there have been changes in the preferences of tourists regarding their holiday destinations in Romania. Started on these considerations, paper based on a logistic model, examines the evolution of the probabilities and scores corresponding to the way the Romanian tourists spend their holidays on the types of tourism agencies, actions and tourist areas in Romania.

Planning a system of permanent sample plots for integrated long-term studies of community-based forest management

1970 ◽  
Vol 16 (2) ◽  
pp. 3-11 ◽  
Author(s):  
H Meilby ◽  
L Puri ◽  
M Christensen ◽  
S Rayamajhi
Keyword(s):  
Forest Management ◽  
Key Words ◽  
Research Note ◽  
Managed Forests ◽  
Community Based ◽  
Permanent Sample Plots ◽  
Long Term Studies

To monitor the development of four community-managed forests, networks of permanent sample plots were established in 2005 at sites in Chitwan, Kaski and Mustang Districts, Nepal. This research note documents the procedures used when preparing for establishment of the plot networks, evaluates the applied stratification of the forest on the basis of data gathered in pilot surveys conducted in the early 2005, and provides a discussion on the implications of the choices made. Key words: Community-managed forests; permanent sample plots; stratification; allocation; estimates Banko Janakari Vol.16(2) 2006 pp.3-11

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