The response of stonefly (Plecoptera) nymphs to seasonal increases in predation risk

2002 ◽  
Vol 80 (6) ◽  
pp. 967-972 ◽  
Author(s):  
Nicole A McCutchen
Keyword(s):  
Rainbow Trout ◽  
Predation Risk ◽  
National Park ◽  
Salvelinus Fontinalis ◽  
Substrate Surface ◽  
Lake Outlet ◽  
Harlequin Ducks ◽  
Brook Char ◽  
A Site ◽  
Increases In Risk

The main objective of this study was to determine if predation risk accounted for the patterns of stonefly (Plecoptera) nymph abundance in the Maligne Valley watershed, Jasper National Park, Alberta. Seasonal declines in nymph density corresponded to increased use of the Maligne Lake Outlet and Lower Maligne River by harlequin ducks (Histrionicus histrionicus). Neither decline represented a shift from aperiodic to nocturnal use of surface rocks. Rather, rock use remained aperiodic throughout the season despite increases in risk. The decline that occurred in the Maligne Lake Outlet also did not represent a shift from small to large surface rocks. These results, when combined with the results of an odor experiment, suggest that nymphs tend to avoid surface rocks when in the presence of harlequin ducks. Nymph density did not decline seasonally in the Middle Maligne River, a site free of harlequin ducks but inhabited year-round by brook char (Salvelinus fontinalis) and rainbow trout (Onchorhynchus mykiss). Nymphs in this site as well as those exposed to char odor were nocturnally biased in their use of the substrate surface. Overall, predation risk appears to play a strong role in the patterns of stonefly nymph abundance in the Maligne Valley watershed, although not in the way originally expected.

Influence of water temperature on behavioural interactions between juvenile brook charr, Salvelinus fontinalis, and rainbow trout, Salmo gairdneri

1986 ◽  
Vol 64 (6) ◽  
pp. 1288-1291 ◽  
Author(s):  
Richard A. Cunjak ◽  
John M. Green
Keyword(s):  
Rainbow Trout ◽  
Competitive Advantage ◽  
Salvelinus Fontinalis ◽  
Salmo Gairdneri ◽  
Optimal Temperature ◽  
Brook Charr ◽  
Thermal Range ◽  
Influence Of Water ◽  
Behavioural Interactions ◽  
Brook Char

Interspecific behavioural interactions between paired brook char (Salvelinus fontinalis) and rainbow trout (Salmo gairdneri) were compared at different water temperatures to test the hypothesis that a species realizes a competitive advantage within its optimal thermal range. Three test temperatures were used: 19 °C (optimal temperature for rainbow trout), 13 °C (optimal temperature for brook charr), and 8 °C (below the optima for both species). Brook charr dominated rainbow trout at both 8 and 13 °C. At 19 °C, neither species displayed an obvious competitive advantage. The time (days) to the establishment of a dominance hierarchy reflected specific optimal temperatures; it was shortest for rainbow trout and brook charr at 19 and 13 °C, respectively. The implications of optimal temperatures and competitive ability are discussed in relation to habitat partitioning in the stream environment.

Food Specialization By Individual Trout

1972 ◽  
Vol 29 (11) ◽  
pp. 1615-1624 ◽  
Author(s):  
James E. Bryan ◽  
P. A. Larkin
Keyword(s):  
Rainbow Trout ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Stomach Contents ◽  
Cutthroat Trout ◽  
Salmo Gairdneri ◽  
Potential Prey ◽  
Repeated Observation ◽  
Size Growth ◽  
Salmo Clarki

Analyses of stomach contents showed that the kinds of prey eaten by brook trout (Salvelinus fontinalis), cutthroat trout (Salmo clarki), and rainbow trout (Salmo gairdneri) were seldom distributed at random among the individuals. Repeated observation of food eaten by individuals in a stream and ponds showed that prey types were eaten in proportions which were characteristic for an individual.Specialization occurred on several different kinds of prey. Although the degree of specialization was higher during shorter intervals, the data suggested that some specialization persisted for half a year. There were no striking correlations between degree of specialization and other individual properties such as size, growth rate, weight of food, number of food items, previous specialization, or area of recapture.In addition to the observations on trout in relatively undisturbed habitats, a field experiment was conducted using laboratory-reared rainbow trout held in small ponds. The food of each trout in the experiment was sampled repeatedly. In analysis of variance, interaction among the individuals and kinds of prey eaten showed that food specialization occurred. Both the absolute and relative abundance of potential prey were constant during the experiment.

Aeromonas salmonicida: Relationship between Extracellular Growth Products and Isolate Virulence

1981 ◽  
Vol 38 (11) ◽  
pp. 1322-1326 ◽  
Author(s):  
Rocco C. Cipriano ◽  
Billy R. Griffin ◽  
Burton C. Lidgerding
Keyword(s):  
Rainbow Trout ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Aeromonas Salmonicida ◽  
Salmo Gairdneri ◽  
Lesion Development ◽  
Culture Supernatants ◽  
Crude Material

Extracellular growth products, extracted from culture supernatants of Aeromonas salmonicida by precipitation with ammonium sulfate and ethanol, were resolved into four fractions by ion-exchange chromatography. Although one of these (fraction II) possessed leukocytolytic activity, virulence of the pathogen was not associated with leukocytotoxicity. A positive correlation was established, however, between virulence and the toxicity of extracted material to cultured rainbow trout gonad (RTG-2) cells. The crude material and fractions II and III from virulent isolates were more toxic to RTG-2 cells than were similar preparations from avirulent isolates. Preparations from virulent isolates caused hemorrhaging, lesion development, and mortality when injected intramuscularly into brook trout (Salvelinus fontinalis) and Atlantic salmon (Salmo solar). Rainbow trout (Salmo gairdneri) were more resistant and lesions could be produced only with fraction II. Fraction II also possessed proteolytic activity.Key words: Aeromonas salmonicida, furunculosis, pathogenicity, salmonids, extracellular products, cytotoxicity, leukocytolysis, proteolysis, fishes

scholarly journals Dose-response relationships of harlequin duck behaviour to noise from low-level military jet over-flights in central Labrador

2004 ◽  
Vol 31 (4) ◽  
pp. 289-298 ◽  
Author(s):  
R. IAN GOUDIE ◽  
IAN L. JONES
Keyword(s):  
Dose Response ◽  
Stress Responses ◽  
Military Training ◽  
Residual Effects ◽  
Whole Body ◽  
Time Activity ◽  
Low Level ◽  
Lake Outlet ◽  
Harlequin Ducks ◽  
Training Area

Concern for the lack of field studies on the effects of low-level military jet over-flights on wildlife resulted in directed research in the Military Training Area of Labrador, 1999–2002. At Fig River, a tributary of the Lower Churchill River, a before-after-control-impact (BACI) study design quantified effects of aircraft over-flights on behaviour of individual harlequin ducks (Histrionicus histrionicus) in the 130 000 km2 Military Training Area of central Labrador. Noise generated from low-level passes (30–100 m above ground level) by military jets was sudden in onset and high in amplitude (>100 dBA), substantially above background sound levels both at Fig Lake outlet (40–50 dBA) and rapid sections of Fig River (60–70 dBA). Harlequin ducks reacted to noise from military jets with alert behaviour, showing a positive dose-response that especially intensified when noise exceeded 80 dBA. Residual effects, in other words, deviations from normal behaviour patterns after initial responses, were decreased courtship behaviour for up to 1.5 h after, and increased agonistic behaviour for up to 2 h after military jet over-flights. Direct behavioural responses to military jet over-flights were of short duration (generally <1 min), and were unlikely to affect critical behaviours such as feeding and resting in the overall time-activity budgets of breeding pairs. However, the presence of residual effects on behaviour implied whole-body stress responses that were potentially more serious; these require further study because they are potentially more detrimental than immediate responses, and may not be detected in studies that focus on readily observed overt responses. A dose-response curve relating particular behaviours of harlequin ducks to associated noise of over-flights could be a valuable conservation tool for the research and mitigation of environmental impacts of aircraft and other noise.

scholarly journals New record of Barrio’s Frog, Insuetophrynus acarpicus Barrio, 1970 (Anura, Rhinodermatidae), in Los Ríos region, Chile

Check List ◽  
2020 ◽  
Vol 16 (6) ◽  
pp. 1519-1522
Author(s):  
Patricio Contreras Bravo ◽  
Fernando Bustos Véliz ◽  
Ignacio Rodriguez-Jorquera
Keyword(s):  
River Basin ◽  
New Record ◽  
National Park ◽  
The World ◽  
Conservation Actions ◽  
A Site

A new record of the Endangered, Chilean endemic Insuetophrynus acarpicus (Barrio 1970) is reported from Alerce Costero National Park, Chile. This species of frog is one of the most threatened anurans in the world, and, consequently, any new record of this species is highly important for assessing its known distribution and proposing urgent conservation actions. The new record is the first known site in the Chaihu&iacute;n river basin, 15 km northwest of a site described by Segura in 2017. The new record fills a gap of the known distribution of I. acarpicus.

Sign in / Sign up

Export Citation Format

Share Document