scholarly journals A review of the effects of Bythotrephes longimanus and calcium decline on zooplankton communities — can interactive effects be predicted?

2015 ◽  
Vol 23 (4) ◽  
pp. 395-413 ◽  
Author(s):  
Shakira S.E. Azan ◽  
Shelley E. Arnott ◽  
Norman D. Yan
Keyword(s):  
Multiple Stressors ◽  
Current Knowledge ◽  
Canadian Shield ◽  
Interactive Effects ◽  
Bythotrephes Longimanus ◽  
Negative Impacts ◽  
The Individual ◽  
Zooplankton Communities ◽  
Shield Lakes ◽  
Review Current

Anthropogenic stressors including acid deposition, invasive species, and calcium (Ca) decline have produced widespread damage to Canadian Shield lakes, especially to their zooplankton communities. Here, we review current knowledge on the individual effects on zooplankton by the non-indigenous predator Bythotrephes longimanus and Ca decline; we identify knowledge gaps in this literature and examine the likely interactive impacts of Bythotrephes invasions and Ca decline on zooplankton. The negative impacts of Bythotrephes longimanus on zooplankton communities are well known, whereas current understanding of the effects of declining Ca on zooplankton is restricted to Daphnia spp.; hence, there is a large knowledge gap on how declining Ca may affect zooplankton communities in general. The co-occurring impacts of Bythotrephes and declining Ca have rarely been studied at the species level, and we expect daphniids, particularly Daphnia retrocurva and Daphnia pulicaria, to be the most sensitive to both stressors. We also expect a synergistic negative interaction on cladocerans in lakes with both stressors, leaving a community dominated by Holopedium glacialis and (or) copepods. Our predictions form testable hypotheses but since species and ecosystem response to multiple stressors are difficult to predict, we may actually see ecological surprises in Canadian Shield lakes as Bythotrephes continues to spread and Ca levels continue to fall.

The differing crustacean zooplankton communities of Canadian Shield lakes with and without the nonindigenous zooplanktivore Bythotrephes longimanus

2003 ◽  
Vol 60 (11) ◽  
pp. 1307-1313 ◽  
Author(s):  
Stephanie A Boudreau ◽  
Norman D Yan
Keyword(s):  
Zooplankton Biomass ◽  
Canadian Shield ◽  
Crustacean Zooplankton ◽  
Bythotrephes Longimanus ◽  
Cladoceran Species ◽  
Zooplankton Communities ◽  
Shield Lakes ◽  
Total Zooplankton Biomass ◽  
Harp Lake

The nonindigenous predatory cladoceran Bythotrephes longimanus is spreading rapidly among Canadian Shield lakes, but only one case study of its impacts exists. In Harp Lake, the abundances of several cladoceran and one cyclopoid species fell after the invasion, and far fewer species benefited. To determine if Harp Lake provides typical results, we compared the summer crustacean zooplankton communities of 17 invaded and 13 noninvaded (reference) lakes in Ontario. The communities of the two lake groups differed. Average species richness was 30% higher in the reference (15.3 species) vs. the invaded lakes (11.8 species). Total zooplankton biomass was significantly lower in the invaded lakes, mainly because of lower abundances of all common epilimnetic cladoceran species. As these results were quite similar to those of Harp Lake, it is apparent that current summer zooplankton communities of Canadian Shield lakes with Bythotrephes differ substantially from noninvaded lakes.

Long-term trends in zooplankton of Dorset, Ontario, lakes: the probable interactive effects of changes in pH, total phosphorus, dissolved organic carbon, and predators

2008 ◽  
Vol 65 (5) ◽  
pp. 862-877 ◽  
Author(s):  
Norman D Yan ◽  
Keith M Somers ◽  
Robert E Girard ◽  
Andrew M Paterson ◽  
W. (Bill) Keller ◽  
...  
Keyword(s):  
Species Richness ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Total Phosphorus ◽  
Canadian Shield ◽  
Interactive Effects ◽  
Crustacean Zooplankton ◽  
Multiple Stressor ◽  
Zooplankton Communities ◽  
Shield Lakes

Time trends in abundance, body size, species richness, and species composition indicate that crustacean zooplankton communities of southern Canadian Shield lakes changed between 1980 and 2003. Total abundance did not decline despite reductions in total phosphorus, but all other metrics changed. Species richness declined in Harp Lake (Ontario, Canada) following its Bythotrephes invasion, but richness increased in three other lakes. Average cladoceran body length increased from 0.6 to 1.0 mm in seven of the lakes, as larger-bodied taxa replaced smaller ones. Correlations with water quality and fish metrics suggest that cladoceran size increases were attributable to many factors: a decline in food availability following declining phosphorus levels increasing the competitive advantage of larger herbivores, a decline in acidity favouring the larger, acid-sensitive daphniids, and reduced risk of planktivory linked to a rise in dissolved organic carbon levels and changes in predation regimes. Zooplankton communities on the Canadian Shield are changing, and these changes are best viewed in a multiple-stressor context. Key anthropogenic stressors have also changed and may do so again if Ca concentrations continue to decline.

An introduction to the Dorset special issue: transforming understanding of factors that regulate aquatic ecosystems on the southern Canadian Shield

2008 ◽  
Vol 65 (5) ◽  
pp. 781-785 ◽  
Author(s):  
Norman D Yan ◽  
Andrew M Paterson ◽  
Keith M Somers ◽  
Wolfgang A Scheider
Keyword(s):  
El Niño ◽  
Aquatic Ecosystems ◽  
Environmental Science ◽  
Multiple Stressors ◽  
El Nino ◽  
Canadian Shield ◽  
Interactive Effects ◽  
Special Issue ◽  
Management Interventions ◽  
South Central

This special issue demonstrates that aquatic ecosystems on the south-central Canadian Shield have changed in many ways over the last three decades. El Niño cycles have synchronized multilake dynamics in lake-water chemistry and in several components of the aquatic biota. Overlain on this cyclic regional pattern, phosphorus, sulphate, and calcium levels have all declined, whereas alkalinity has not yet risen in the most acid-sensitive study lakes, despite large reductions in SO2 emissions. Further, novel and unanticipated stressors have appeared, including nonindigenous predator introductions, Ca decline, salinity increase, and autumn spikes in metals following El Niño induced droughts. The resident biota are clearly responding not only to the familiar historical phosphorus and acid stressors, but also to the interactive effects of changes in multiple stressors in a warming environment. Lakes are best managed with an understanding of dominant limnological trends, their causes, and their responses to past management interventions. The research conducted at the Dorset Environmental Science Centre indicates “progress but no cigar” on acid rain, proof of climate variability as a direct and indirect regulator of south-central Shield ecosystems, and the emergence of novel stressors, the effects of which we cannot yet fully predict.

Will environmental calcium declines hinder Bythotrephes establishment success in Canadian Shield lakes?

2012 ◽  
Vol 69 (5) ◽  
pp. 810-820 ◽  
Author(s):  
Natalie Kim ◽  
Bjørn Walseng ◽  
Norman David Yan
Keyword(s):  
Lake Water ◽  
Calcium Content ◽  
Dry Mass ◽  
Canadian Shield ◽  
Direct Effects ◽  
Bythotrephes Longimanus ◽  
Establishment Success ◽  
Population Growth Rates ◽  
Calcium Decline ◽  
Shield Lakes

Recently, calcium-rich daphniids have declined on the Canadian Shield in response to falling lake-water calcium concentrations, or [Ca]. Meanwhile the invader Bythotrephes longimanus , a predator that feeds on Daphnia , continues to spread. Our goal was to determine if ongoing calcium declines might directly or indirectly affect Bythotrephes ’ establishment success. To address direct effects, we provide the first quantification of Bythotrephes’ calcium content, which is very low (0.03% as dry mass) compared with other Cladocera. We also examined the effects of differing [Ca] (0.1–2.6 mg·L–1) on Bythotrephes’ performance in the laboratory. For all [Ca], population growth rates remained positive, indicating that Bythotrephes has great tolerance of low [Ca]. Finally, we examined Bythotrephes’ distribution in relation to [Ca] on the Shield where is it relatively new, alongside its distribution in Norway where it is endemic and found that Bythotrephes inhabits very low calcium environments in Norway (minimum = 0.2 mg·L–1). These results suggest that Bythotrephes establishment in Canada is currently not — and in the future will likely not — be limited by falling calcium. Rather, as Bythotrephes is more tolerant of low [Ca] than are its daphniid prey, we propose that both calcium decline and Bythotrephes invasions may contribute to Daphnia decline.

scholarly journals Pollutants and Their Interaction with Diseases of Social Hymenoptera

Insects ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 153 ◽  
Author(s):  
Heike Feldhaar ◽  
Oliver Otti
Keyword(s):  
Heavy Metals ◽  
Particulate Matter ◽  
Social Insects ◽  
Sublethal Effects ◽  
Multiple Stressors ◽  
Current Knowledge ◽  
Fine Particulate Matter ◽  
Interactive Effects ◽  
Social Hymenoptera ◽  
Fine Particulate

Many insect species, including social insects, are currently declining in abundance and diversity. Pollutants such as pesticides, heavy metals, or airborne fine particulate matter from agricultural and industrial sources are among the factors driving this decline. While these pollutants can have direct detrimental effects, they can also result in negative interactive effects when social insects are simultaneously exposed to multiple stressors. For example, sublethal effects of pollutants can increase the disease susceptibility of social insects, and thereby jeopardize their survival. Here we review how pesticides, heavy metals, or airborne fine particulate matter interact with social insect physiology and especially the insects’ immune system. We then give an overview of the current knowledge of the interactive effects of these pollutants with pathogens or parasites. While the effects of pesticide exposure on social insects and their interactions with pathogens have been relatively well studied, the effects of other pollutants, such as heavy metals in soil or fine particulate matter from combustion, vehicular transport, agriculture, and coal mining are still largely unknown. We therefore provide an overview of urgently needed knowledge in order to mitigate the decline of social insects.

CYBERBULLYING PADA MEDIA SOSIAL: Menyoroti Perilaku Cyberbullying Menurut Perspektif Model Konseling Realitas

2020 ◽  
Author(s):  
Darimis Darimis Darimis
Keyword(s):  
Social Relationships ◽  
Choice Theory ◽  
Human Beings ◽  
Important Goal ◽  
Application Procedure ◽  
Negative Impacts ◽  
Use Of The Internet ◽  
The Individual ◽  
Counseling Model ◽  
Real Responsibility

Use of the Internet has changed the paradigm of human beings communicate with one another, especially on social media. Indonesia as one of the highest in the world Facebook users make significant consequences specifically for teenagers. The trend using Facebook by teenagers has created negative impacts that is the rise of cyberbullying.Cyberbullying can significantly influence the lives of teenagers and it can be a huge burden as it can happen for a long period of time. In cyberbullying, there are cyber bullies and cyber victims as individuals involved to make the message as a reference the behavior of cyberbullying. This paper attempts to looking at the perspective of the cyberbullying behavior by reality counseling model, because reality counseling as one of the models of counseling that focuses on behavior now unrealistic and dysfunctional.Reality counseling based on the choice theory, counselee make more effective choices about the development of relational satisfactory with others. The most important goal of therapy is to make people aware of the reality that the real responsibility for her behavior was himself. This counseling can helping the individual reality of cyberbullying offenders realize the consequences of his behavior, responsible, develop positive social relationships through the application procedure techniques WDEP and techniques reality Counseling.

Methods for assessing territory pollution by oil or petroleum product spills

2020 ◽  
pp. 140-146
Author(s):  
S. I. Chelombitko ◽  
V. V. Piven
Keyword(s):  
Oil And Gas ◽  
Radiant Energy ◽  
Petroleum Products ◽  
Individual Characteristics ◽  
Oil And Gas Fields ◽  
Northern Regions ◽  
Negative Impacts ◽  
The Individual ◽  
Destructive Processes ◽  
Gas Fields

During the development of oil and gas fields and transportation of hydrocarbons, the ecology of regions is subject to various negative impacts. The most severe consequences for the environment are caused by accidental spills of oil or petroleum products, which occur due to through damage to pipelines. Polluted territories are subject to mandatory reclamation in accordance with government regulations and industry regulations. However, despite the measures taken by the administrations of the northern regions to increase the rate of reclamation of damaged territories in recent years, there has been a trend of growth of areas contaminated with hydrocarbons.Various remediation technologies that have been tested in warm and temperate climates are not very effective in regions with permafrost. Pollution of the daytime surface with oil or petroleum products leads to an increase in the absorption of the sun's radiant energy, the growth of the seasonal thaw layer and the development of destructive processes for the territory. To achieve a positive effect as a result of rehabilitation measures, it is necessary to take into account the individual characteristics of the territory and the extent of its pollution.

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