Occurrence of the Acanthocephalan Echinorhynchus leidyi (Van Cleave, 1924) in Mysis relicta

1983 ◽  
Vol 61 (2) ◽  
pp. 460-462 ◽  
Author(s):  
S. B. Prychitko ◽  
R. W. Nero
Keyword(s):  
Intermediate Host ◽  
Definitive Host ◽  
Lake Trout ◽  
Parasite Prevalence ◽  
Salvelinus Namaycush ◽  
Mysis Relicta ◽  
Northwestern Ontario

Mysis relicta has been identified as an intermediate host of the acanthocephalan Echinorhynchus leidyi (Van Cleave, 1924) Golvan, 1969 in four of eight lakes examined in northwestern Ontario. Parasite prevalence in Mysis relicta ranged from less than 1 to 3.6%. Lake trout (Salvelinus namaycush) are a common definitive host.

The transmission, life span, and population biology of Cystidicola cristivomeri White, 1941 (Nematoda: Habronematoidea) in char, Salvelinus spp.

1981 ◽  
Vol 59 (3) ◽  
pp. 498-509 ◽  
Author(s):  
Geoff A. Black ◽  
Murray W. Lankester
Keyword(s):  
Population Biology ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Mature Female ◽  
Arctic Char ◽  
Mysis Relicta ◽  
Northwestern Ontario ◽  
Third Stage ◽  
Paratenic Hosts ◽  
Fish Hosts

The population biology of Cystidicola cristivomeri White, 1941 was investigated in lake trout, Salvelinus namaycush, in three lakes in northwestern Ontario and in arctic char, S. alpinus, in Gaviafaeces Lake, Northwest Territories. Young lake trout fed selectively on large Mysis relicta, which were more frequently infected with C. cristivomeri (up to 5.1%) than small mysids. Pontoporeia affinis was not a suitable intermediate host in nature and there was no evidence that fish paratenic hosts were important in transmitting this nematode to lake trout.Most C. cristivomeri appear to live at least 10 years in naturally infected lake trout and arctic char. In these fishes the size of C. cristivomeri infrapopulations is determined by several factors. The feeding preferences of fish hosts and the availability of forage in individual lakes determine the extent and duration of feeding on M. relicta. Each naturally infected mysid contains only one third-stage C. cristivomeri larva. In the swim bladder of infected fishes, the proportion of female C. cristivomeri reaching sexual maturity and the length of females is inversely related to the total number of worms present. The length of mature female worms, in turn, is positively correlated with the rate at which they produce eggs. As a result, the egg output of C. cristivomeri at the infrapopulation level is density dependent.

Multiple Trophic Level Structuring in Salvelinus–Coregonus Assemblages in Boreal Forest Lakes

1993 ◽  
Vol 50 (7) ◽  
pp. 1442-1455 ◽  
Author(s):  
Edward A. Trippel ◽  
F. William H. Beamish
Keyword(s):  
Body Size ◽  
Lake Trout ◽  
Zooplankton Community ◽  
Salvelinus Namaycush ◽  
High Conductivity ◽  
Top Down ◽  
Mysis Relicta ◽  
Northwestern Ontario ◽  
Coregonus Artedi ◽  
Forest Lakes

Hypolimnetic trophic interactions were examined among lake trout (Salvelinus namaycush), cisco (Coregonus artedi), zooplankton, and macroinvertebrates in six northwestern Ontario lakes varying sevenfold in conductivity. Faster growth and larger body size of lake trout in high-conductivity lakes were associated with larger meal sizes, earlier entry of cisco into their diet, and consumption of relatively few, large-bodied prey. Cisco preyed on zooplankton and macroinvertebrates. Cisco were abundant, large bodied, and fast growing in high-conductivity lakes. In one low-conductivity lake (Greenwich Lake), lake trout were 12 times as abundant as cisco whereas in all other lakes, lake trout to cisco ratios were ~ 1:1 or less regardless of conductivity. In Greenwich Lake, lake trout consumed large quantities of age-0 cisco and Mysis relicta, which was associated with "top-down" trophic structuring. Food web analyses strongly suggest that in Greenwich Lake the high abundance of piscivores resulted directly in a low abundance of planktivores and indirectly in a large-bodied zooplankton community and planktivores with rapid growth rates.

Land water linkages: influences of riparian deforestation on lake thermocline depth and possible consequences for cold stenotherms

1997 ◽  
Vol 54 (6) ◽  
pp. 1299-1305 ◽  
Author(s):  
Robert France
Keyword(s):  
Thermal Stratification ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Thermocline Depth ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Riparian Trees ◽  
Tree Removal ◽  
Riparian Tree ◽  
Land Water

The purpose of the present study was to determine if riparian deforestation would expose lake surfaces to stronger winds and therefore bring about deepening of thermoclines and resulting habitat losses for cold stenotherms such as lake trout (Salvelinus namaycush). Removal of protective riparian trees through wind blowdown and two wildfires was found to triple the overwater windspeeds and produce thermocline deepening in two lakes at the Experimental Lakes Area. A survey of thermal stratification patterns in 63 northwestern Ontario lakes showed that lakes around which riparian trees had been removed a decade before through either clearcutting or by a wildfire were found to have thermocline depths over 2 m deeper per unit fetch length compared with lakes surrounded by mature forests. Riparian tree removal will therefore exacerbate hypolimnion habitat losses for cold stenotherms that have already been documented to be occurring as a result of lake acidification, eutrophication, and climate warming.

Pelagic distribution of lake trout (Salvelinus namaycush) in small Canadian Shield lakes with respect to temperature, dissolved oxygen, and light

1998 ◽  
Vol 55 (1) ◽  
pp. 170-179 ◽  
Author(s):  
Todd J Sellers ◽  
Brian R Parker ◽  
David W Schindler ◽  
William M Tonn
Keyword(s):  
Light Intensity ◽  
Dissolved Oxygen ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Canadian Shield ◽  
Small Lakes ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Oxygenated Water ◽  
Shield Lakes

The distribution of lake trout (Salvelinus namaycush) with respect to water temperature, dissolved oxygen, and light intensity was surveyed in three small Canadian Shield lakes at the Experimental Lakes Area, northwestern Ontario. Based on hydroacoustic and gillnet surveys, there was considerable variation among lakes in temperatures occupied by lake trout during the summer. During the day, lake trout were concentrated at 4-8°C in Lake 375, broadly distributed from 6 to 15°C in Lake 442, and concentrated in the epilimnion at 19°C in Lake 468. At night, lake trout in all lakes occupied epilimnetic waters at 19-20°C. Lake trout inhabited highly oxygenated water, with 75-90% of fish at >6 mg dissolved oxygen ·L-1 throughout the spring and summer in all three lakes. Light intensity did not affect lake trout distribution in Lake 468 but may have contributed to lake trout daytime descent into cool waters in Lakes 375 and 442. We suggest that previously assumed niche boundaries of lake trout do not adequately describe critical habitat for the species in small lakes, the same lakes that are likely most sensitive to erosion of such habitat.

Performance of temperature and dissolved oxygen criteria to predict habitat use by lake trout (Salvelinus namaycush)This paper is part of the series “Forty Years of Aquatic Research at the Experimental Lakes Area”.

2009 ◽  
Vol 66 (11) ◽  
pp. 2011-2023 ◽  
Author(s):  
John M. Plumb ◽  
Paul J. Blanchfield
Keyword(s):  
Habitat Use ◽  
Dissolved Oxygen ◽  
Thermal Stratification ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Experimental Lakes Area ◽  
Lake Volume ◽  
Northwestern Ontario ◽  
Environmental Extremes

We compared theoretical habitat volumes, determined from traditional combinations of temperature and dissolved oxygen concentration (DO) boundaries, with in situ habitat use by acoustically tagged lake trout ( Salvelinus namaycush ). The widely used criteria of 8–12 °C underestimated lake trout habitat use by 68%–80%. Instead, combined temperature (<12 or 15 °C) and DO (>4 or 6 mg·L–1) criteria most closely matched lake trout habitat use, had a similar seasonal trend as the tagged fish, suggested modest reductions (5% of total lake volume) in habitat during a warmer year, and performed best when the constraints of temperature and DO were most limiting. All data were collected in a small boreal shield lake (27 ha, zmax = 21 m) at the Experimental Lakes Area in northwestern Ontario, Canada, during two contrasting periods of thermal stratification (2003: warmer and longer; 2004: cooler and shorter), providing an assessment of observed and theoretical habitat volumes over current environmental extremes.

Survival and Development of Lake Trout (Salvelinus namaycush) embryos in an Acidified Lake in Northwestern Ontario

1990 ◽  
Vol 47 (2) ◽  
pp. 236-243 ◽  
Author(s):  
L. C. Mohr ◽  
K. H. Mills ◽  
J. F. Klaverkamp
Keyword(s):  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Experimental Lakes Area ◽  
Embryo Survival ◽  
Embryo Mortality ◽  
Recruitment Failure ◽  
Northwestern Ontario ◽  
Survival And Development ◽  
Population Recruitment ◽  
Experimental Acidification

Survival and development of lake trout (Salvelinus namaycush) embryos from L223 in the Experimental Lakes Area, northwestern Ontario, were evaluated from 1979 (pH 5.6) to 1982 (pH 5.1). Survival of L223 embryos was not significantly correlated to lake pH during experimental acidification. Also, embryo mortality in L223 was not significantly different from that of lake trout embryos in two reference lakes, L224 and L468. Survival of L223 embryos was not improved when they were incubated in nonacidified lakes. Embryo mortality was highest in all lakes (33–81%) within 15 d of fertilization. Mortality was negligible from Day 15 until the termination of the seasonal observations (Day 120 or 150). High variability in embryo survival existed between individual females within a single lake. The mean size of eggs from L223 lake trout decreased significantly from 1979 to 1982. Recruitment failures occurred in L223 from 1980 to 1982. We hypothesize that lake trout recruitment failure in L223 occurred between the posthatching period (spring) and actual recruitment into the population as young-of-the-year (fall) and that embryo mortality in this lake was not critical to population recruitment.

Responses of Fish Populations in Lake 223 to 8 Years of Experimental Acidification

1987 ◽  
Vol 44 (S1) ◽  
pp. s114-s125 ◽  
Author(s):  
K. H. Mills ◽  
S. M. Chalanchuk ◽  
L. C. Mohr ◽  
I. J. Davies
Keyword(s):  
Fathead Minnow ◽  
Lake Trout ◽  
Pimephales Promelas ◽  
Salvelinus Namaycush ◽  
Early Years ◽  
White Sucker ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Slimy Sculpin ◽  
Experimental Acidification

Lake 223 in the Experimental Lakes Area, northwestern Ontario, was experimentally acidified with sulfuric acid from 1976 (initial average pH 6.49) to 1981 (average pH 5.02), and then maintained at pH 5.02 to 5.13 from 1981 to 1983. Lake trout (Salvelinus namaycush), white sucker (Catostomus commersoni), fathead minnow (Pimephales promelas), and slimy sculpin (Cottus cognatus) were abundant at the onset of acidification. A decline in the abundance of fathead minnow began in 1979 (pH 5.64), and was followed first by a rapid increase in number of pearl dace (Semotilus margarita) in 1980 (pH 5.59) and then a rapid decrease in 1982 (pH 5.09). The abundance of slimy sculpin decreased rapidly in 1979. Abundances of lake trout and white sucker increased during the early years of acidification, but declined following consecutive recruitment failures starting in 1980 for trout and in 1981 for white suckers. By 1982 recruitment had ceased for all Lake 223 fishes. Survival of lake trout [Formula: see text] age 1 decreased in 1982 and 1983, but no other changes in survival of fish [Formula: see text] age 1 were detected for lake trout or white sucker. By spring 1983 many lake trout were emaciated due to losses of the lake trout food organisms. No changes in growth of lake trout and white suckers occurred during the initial years of acidification, but growth of lake trout slowed in 1982 and growth of white sucker increased in 1979.

Effects of experimental clearcut logging on thermal stratification, dissolved oxygen, and lake trout (Salvelinus namaycush) habitat volume in three small boreal forest lakes

2000 ◽  
Vol 57 (S2) ◽  
pp. 82-91 ◽  
Author(s):  
Robert J Steedman ◽  
Robert S Kushneriuk
Keyword(s):  
Wind Speed ◽  
Thermal Stratification ◽  
Lake Trout ◽  
Late Summer ◽  
Water Clarity ◽  
Salvelinus Namaycush ◽  
Thermocline Depth ◽  
Buffer Strip ◽  
Northwestern Ontario ◽  
Clearcut Logging

Clearcut logging around three 30- to 40-ha dimictic northwestern Ontario lakes was associated with increases of 5% or less in midlake wind speed and no measurable changes in spring and fall circulation efficiency or duration of stratification. Water clarity, indexed as the depth at which photosynthetically active radiation was 1% of surface intensity, declined by 25% after 3 years. Late-summer thermoclines were about 1 m shallower in two lakes after logging, but it was not possible to exclude weather as a factor. None of the lakes showed significant declines in lake trout (Salvelinus namaycush) habitat volume. A forested shoreline buffer strip around one of the lakes prevented increases in midlake wind speed but did not prevent declines in water clarity and thermocline depth.

Pelagic Food Chain Structure in Ontario Lakes: A Determinant of Mercury Levels in Lake Trout (Salvelinus namaycush)

1994 ◽  
Vol 51 (2) ◽  
pp. 381-389 ◽  
Author(s):  
Gilbert Cabana ◽  
Alain Tremblay ◽  
Jacob Kalff ◽  
Joseph B. Rasmussen
Keyword(s):  
Food Chain ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Chain Structure ◽  
Food Chains ◽  
Micropterus Dolomieu ◽  
Species Introduction ◽  
Mysis Relicta ◽  
Recent Species ◽  
Glacial Relict

The trophic structure of pelagic communities in glaciated regions is highly variable due to restricted dispersal of glacial relict taxa and recent species introduction. Much of the between-lake variation in Hg in lake trout (Salvelinus namaycush) flesh from the St. Lawrence system (non-point-source contaminated lakes), which spans more than two orders of magnitude (0.03–3.96 μg/g), results from differences in the length of pelagic food chains. Hg levels from the longest food chains where pelagic forage fish and the crustacean Mysis relicta were present were about 3.6-fold higher than those from the shortest food chains where these last two trophic components were missing. A lack of correlation between Hg levels in small-mouth bass (Micropterus dolomieu), which do not exploit the pelagic food chain, and the length of the pelagic food chain confirmed that the positive relationship observed in lake trout could not be attributed to the confounding effect of some physicochemical factors covarying with our pelagic food chain classification. Our results confirmed that the food chain biomagnification model developed by Rasmussen et al. (1990. Can. J. Fish. Aquat. Sci. 47: 2030–2038) to predict PCB levels in lake trout can also be applied to Hg biomagnification.

Evidence of successful river spawning by lake trout (Salvelinus namaycush) in the Lower Niagara River, Lake Ontario

2021 ◽  
Author(s):  
Alexander Gatch ◽  
Dimitry Gorsky ◽  
Zy Biesinger ◽  
Eric Bruestle ◽  
Kelley Lee ◽  
...  
Keyword(s):  
Lake Trout ◽  
Lake Ontario ◽  
Salvelinus Namaycush ◽  
Niagara River
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