Effects of Forest Spraying with DDT on Aquatic Insects of Salmon Streams in New Brunswick

1967 ◽  
Vol 24 (4) ◽  
pp. 769-805 ◽  
Author(s):  
F. P. Ide
Keyword(s):  
New Brunswick ◽  
Aquatic Insects ◽  
Late Summer ◽  
Bottom Fauna ◽  
Small Populations ◽  
Single Application ◽  
Severe Reduction ◽  
Large Populations

Sampling of emerging aquatic insects by cage-traps on a 24-hr basis showed the effects on the stream fauna of spraying forests with DDT at [Formula: see text] in June. Except for a few individuals that presumably emerged from unaffected pupae and nymphs, there was an interval of several weeks after spraying when no emergence occurred. From about the middle of August, however, large populations of very small insects, mainly chironomids, emerged in the spray year. The year after spraying, as compared with the spray year, there was an increased variety including some larger species.In following years there was further recovery by increase in larger forms through reproduction from residual small populations. The caddisflies recovered more slowly than other groups. After a single application of spray the fauna had practically recovered qualitatively in 2 or 3 years in some groups but usually not for 4 years or more in caddisflies. With a further similar spray applied within 3 years a reduction occurred equal in severity to that of the original spraying.From the standpoint of feeding of the young salmon, significant facts are: (a) the severe reduction in the bottom fauna of larvae and nymphs of all sizes in the first weeks after spraying; (b) the large populations of small larvae, mainly chironomids, developing in late summer of the spray year and so available to fry; (c) increasing numbers of larger insects the year after spraying and subsequent years.

scholarly journals Nematodes in relation to plant growth, IV. Pratylenchus penetrans (Cobb) on orchard trees.

1962 ◽  
Vol 10 (4) ◽  
pp. 286-296 ◽  
Author(s):  
H. Hoestra ◽  
M. Oostenbrink
Keyword(s):  
Plant Growth ◽  
Shoot Growth ◽  
Sandy Soils ◽  
Good Evidence ◽  
Small Populations ◽  
Pratylenchus Penetrans ◽  
Experimental Conditions ◽  
Nematode Density ◽  
Large Populations ◽  
Considerable Damage

The damage caused by Pratylenchus penetrans in orchards is discussed. In 2 experimental fields containing 4 varieties of apple, there was good evidence of a decrease in yield with increased nematode density before apple seedlings were planted. Heavy nematode infestations reduced shoot growth by more than 50%. A concentration of 100 nematodes per 300 ml. of soil may cause considerable damage. The process of infestation and symptoms of nematode attack under field and experimental conditions are discussed. In clean cultivated orchards on light sandy soils there are often large populations in the roots and very small populations in the soil but on heavier soils, the converse is true. Hoestra & Oostenbrink conclude without doubt that P. penetrans is an important cause of replant problems in orchards. H.R. W. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Unexpected heterozygosity in an island mouflon population founded by a single pair of individuals

2006 ◽  
Vol 274 (1609) ◽  
pp. 527-533 ◽  
Author(s):  
Renaud Kaeuffer ◽  
David W Coltman ◽  
Jean-Louis Chapuis ◽  
Dominique Pontier ◽  
Denis Réale
Keyword(s):  
Genetic Diversity ◽  
Wild Population ◽  
Ovis Aries ◽  
Stochastic Simulations ◽  
Single Pair ◽  
Small Populations ◽  
Short Period ◽  
Large Populations ◽  
History Of ◽  
Over Time

In population and conservation genetics, there is an overwhelming body of evidence that genetic diversity is lost over time in small populations. This idea has been supported by comparative studies showing that small populations have lower diversity than large populations. However, longitudinal studies reporting a decline in genetic diversity throughout the whole history of a given wild population are much less common. Here, we analysed changes in heterozygosity over time in an insular mouflon ( Ovis aries ) population founded by two individuals in 1957 and located on one of the most isolated locations in the world: the Kerguelen Sub-Antarctic archipelago. Heterozygosity measured using 25 microsatellite markers has actually increased over 46 years since the introduction, and exceeds the range predicted by neutral genetic models and stochastic simulations. Given the complete isolation of the population and the short period of time since the introduction, changes in genetic variation cannot be attributed to mutation or migration. Several lines of evidence suggest that the increase in heterozygosity with time may be attributable to selection. This study shows the importance of longitudinal genetic surveys for understanding the mechanisms that regulate genetic diversity in wild populations.

Unequal Voting

2019 ◽  
pp. 175-192
Author(s):  
James Lindley Wilson
Keyword(s):  
Electoral College ◽  
Small Populations ◽  
Political Equality ◽  
Voting Power ◽  
Political Inequality ◽  
The Us ◽  
Large Populations ◽  
Us Senate

This chapter assesses how the inequalities in voting power involved in the US Senate and in the Electoral College used to elect the president violate the requirements of political equality. The Senate comprises two senators from each state. States with large populations get the same number of votes in the Senate as do states with small populations. Because the states vary considerably in population, there are large inequalities in how many citizens are represented by a senate delegation. This unequal representation of individuals in the Senate constitutes objectionable political inequality. The Senate is thus unjustifiably undemocratic. This conclusion has implications for the election of the US president, as the Electoral College process for such election tracks what the chapter argues is the malapportionment of the Senate. This inequality, too, is objectionable, and it should be eliminated. The reasons for a more egalitarian election of the president are all the more urgent given that the inequalities in the Senate are much more constitutionally entrenched, and thus likely to remain. The election of the president should mitigate that inequality rather than exaggerate it.

scholarly journals Population size, habitat fragmentation, and the nature of adaptive variation in a stream fish

2014 ◽  
Vol 281 (1790) ◽  
pp. 20140370 ◽  
Author(s):  
Dylan J. Fraser ◽  
Paul V. Debes ◽  
Louis Bernatchez ◽  
Jeffrey A. Hutchings
Keyword(s):  
Genetic Variation ◽  
Habitat Fragmentation ◽  
Population Size ◽  
Brook Trout ◽  
Small Populations ◽  
Adaptive Genetic Variation ◽  
Genetic Population ◽  
Fragmented Populations ◽  
Large Populations ◽  
Adaptive Differentiation

Whether and how habitat fragmentation and population size jointly affect adaptive genetic variation and adaptive population differentiation are largely unexplored. Owing to pronounced genetic drift, small, fragmented populations are thought to exhibit reduced adaptive genetic variation relative to large populations. Yet fragmentation is known to increase variability within and among habitats as population size decreases. Such variability might instead favour the maintenance of adaptive polymorphisms and/or generate more variability in adaptive differentiation at smaller population size. We investigated these alternative hypotheses by analysing coding-gene, single-nucleotide polymorphisms associated with different biological functions in fragmented brook trout populations of variable sizes. Putative adaptive differentiation was greater between small and large populations or among small populations than among large populations. These trends were stronger for genetic population size measures than demographic ones and were present despite pronounced drift in small populations. Our results suggest that fragmentation affects natural selection and that the changes elicited in the adaptive genetic composition and differentiation of fragmented populations vary with population size. By generating more variable evolutionary responses, the alteration of selective pressures during habitat fragmentation may affect future population persistence independently of, and perhaps long before, the effects of demographic and genetic stochasticity are manifest.

scholarly journals Biomorpher: Interactive evolution for parametric design

2018 ◽  
Vol 16 (2) ◽  
pp. 144-163 ◽  
Author(s):  
John Harding ◽  
Cecilie Brandt-Olsen
Keyword(s):  
Parametric Design ◽  
Performance Criteria ◽  
Evolutionary Design ◽  
Parametric Modelling ◽  
Small Populations ◽  
Design Exploration ◽  
Wide Range ◽  
Large Populations ◽  
Modelling Environment ◽  
User Motivation

Combining graph-based parametric design with metaheuristic solvers has to date focused solely on performance-based criteria and solving clearly defined objectives. In this article, we outline a new method for combining a parametric modelling environment with an interactive Cluster-Orientated Genetic Algorithm. In addition to performance criteria, evolutionary design exploration can be guided through choice alone, with user motivation that cannot be easily defined. As well as numeric parameters forming a genotype, the evolution of whole parametric definitions is discussed through the use of genetic programming. Visualisation techniques that enable mixing small populations for interactive evolution with large populations for performance-based optimisation are discussed, with examples from both academia and industry showing a wide range of applications.

Effects of Forest Spraying with DDT in New Brunswick on Food of Young Atlantic Salmon

1967 ◽  
Vol 24 (4) ◽  
pp. 807-822 ◽  
Author(s):  
Miles H. A. Keenleyside
Keyword(s):  
Atlantic Salmon ◽  
New Brunswick ◽  
Aquatic Insects ◽  
Fish Food ◽  
Active Selection

Food in stomachs of young Atlantic salmon from the Northwest Miramichi River, N.B., changed following aerial DDT spraying of the surrounding watershed. Before spraying, young salmon typically ate immature aquatic insects, fry (underyearlings) concentrating on Diptera and small Ephemeroptera, and parr (overyearlings) on Diptera, Trichoptera, and all sizes of Ephemeroptera. Reduction of all aquatic insects by DDT was soon followed by resurgence of Chironomidae and other Diptera, and surviving fry fed heavily on these; parr fed on Diptera but also ate snails, worms, and fish, previously unimportant in their diet. Five years after the last spraying the pre-spray complexity of young salmon food was being approached. Trichoptera were slowest of the major fish-food types to reappear in stomachs.In fry stomachs Ephemeroptera, and in parr stomachs Ephemeroptera and Trichoptera, were relatively more abundant than in the surrounding stream fauna. Greater availability of these insects and active selection by fish are discussed as possible causes of these relationships.

Interaction of nutrient supply and plant density in relation to maximal yield of the swede crop

1968 ◽  
Vol 70 (3) ◽  
pp. 369-373 ◽  
Author(s):  
R. W. Lang ◽  
J. C. Holmes
Keyword(s):  
Plant Density ◽  
Total Yield ◽  
Nutrient Supply ◽  
Matter Content ◽  
Human Consumption ◽  
Dry Matter Content ◽  
Small Populations ◽  
Plant Populations ◽  
Maximal Yield ◽  
Large Populations

SUMMARYThe effects of changing plant density and nutrient supply on the yield of swedes were measured in nine experiments over 3 years. With small populations, a large nutrient supply was required to reach the maximal yield of roots, but with large plant populations the same nutrient rate depressed yield. This interaction is illustrated by a response surface, and reasons for it are discussed. The interaction is of limited importance in practice because it was small over the range of population and nutrient supply commonly used. Even with small populations, the compensation achieved by applying more fertilizer was uneconomic. On crops with large populations, such as swedes for human consumption, however, the normal recommended rate of fertilizer should not be exceeded because of loss of yield as well as increased cost. More fertilizer and greater plant density were needed to give maximal total yield (roots + tops) than of roots alone. Effects of nutrient supply and plant population on plant establishment and dry-matter content of the swedes are discussed.

The Seasonal Availability to Sheep of Infective Nematode Larvae on Pasture

1959 ◽  
Vol 33 (4) ◽  
pp. 281-288 ◽  
Author(s):  
J. H. Tetley
Keyword(s):  
Acquired Resistance ◽  
Late Summer ◽  
Post Mortem ◽  
Post Mortem Examination ◽  
Infective Larvae ◽  
Nematode Larvae ◽  
Large Populations ◽  
Minor Significance

The seasonal availability of sheep nematode infective larvae under normal farm conditions was investigated by exposing lambs reared worm free for two weekly periods in the fields. Data were collected in the form of populations found at post mortem examination.It was found that Nematodirus spp. were acquired in greatest numbers in the autumn after the date by which lambs normally have acquired resistance to superinfection. The conclusion was that self-augmentation of Nematodirus parasitism in lambs resulting from eggs the lambs conveyed to the ground was of minor significance and that eggs reaching the ground in one season are the source of parasitism in lambs in the following spring.It was found that greatest numbers of Haemonchus conlortus were acquired in summer. Heavy contamination of pasture with eggs of this species by ewes in the spring did not result in large populations in their lambs. It was concluded that the extent of parasitism in lambs in the late summer and autumn was contingent on there being favourable conditions at that time of the year for the development of infective larvae.

Southeastward shorebird migration over Nova Scotia and New Brunswick in autumn: a radar study

1979 ◽  
Vol 57 (1) ◽  
pp. 107-124 ◽  
Author(s):  
W. John Richardson
Keyword(s):  
High Pressure ◽  
New Brunswick ◽  
Far East ◽  
Late Summer ◽  
Bay Of Fundy ◽  
Magnetic Disturbance ◽  
Fair Weather ◽  
Wind Drift ◽  
Cold Fronts ◽  
K Index

Shorebirds departed over the Atlantic intermittently by night and (in lesser numbers) day in late summer and early autumn. Migrations were broad-front and usually began inland (including Bay of Fundy), often 1–2 h before sunset. Tracks were straight, with daily means of 110–170° (overall mean 134°). About 69% were flying on tracks directed too far east to reach South America without a course change; the roles of wind drift and heading adjustments in effecting this course change are uncertain. Ground speeds were 74 ± SD 17 km/h; altitudes were often high (mean 2.0 km, 5% of flocks above 4.4 km, highest 6.65 km). Many departed with W–NW winds and fair weather behind cold fronts or E or N of high pressure areas, but some took off ahead of or caught up with and penetrated cold fronts. Mean tracks were correlated with wind direction, but were rarely downwind. Their deviation from downwind was unrelated to visibility, cloud, or magnetic disturbance (K index). Dispersion of tracks did not change consistently during nights or days and was unrelated to wind or K index. Dispersion at night was slightly greater in inclement than fair weather.

Effects on Aquatic Insects of Forest Spraying with Phosphamidon in New Brunswick

1967 ◽  
Vol 24 (4) ◽  
pp. 823-832 ◽  
Author(s):  
C. D. Grant
Keyword(s):  
New Brunswick ◽  
Aquatic Insects ◽  
No Reduction ◽  
Number Of Individuals ◽  
Harmful Effects

No harmful effects on aquatic insects were detected in two New Brunswick streams after forest spraying with phosphamidon [Formula: see text] in 1962 and 1963. Comparison of one pre-spray and two post-spray series of bottom samples showed no reduction in number of orders (and families in the case of Diptera) and no abnormal decline in the number of individuals. In numbers and variety of insects emerging daily into stream cages and of insects drifting onto vertical screens in the streams, no changes were attributable to phosphamidon.

Sign in / Sign up

Export Citation Format

Share Document