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.

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.

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.

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.

Empirical evaluation of predator-driven diel vertical migration in Lake Superior

2010 ◽  
Vol 67 (3) ◽  
pp. 473-485 ◽  
Author(s):  
Jason D. Stockwell ◽  
Thomas R. Hrabik ◽  
Olaf P. Jensen ◽  
Daniel L. Yule ◽  
Matthew Balge
Keyword(s):  
Vertical Migration ◽  
Diel Vertical Migration ◽  
Lake Superior ◽  
Empirical Evaluation ◽  
Salvelinus Namaycush ◽  
Seasonal Patterns ◽  
Mysis Relicta ◽  
Size Dependent ◽  
Coregonus Artedi ◽  
Using Data

Recent studies on Lake Superior suggest that diel vertical migration (DVM) of prey (generalized Coregonus spp.) may be influenced by the density of predatory siscowet ( Salvelinus namaycush ). We empirically evaluated this hypothesis using data from acoustic, midwater trawl, and bottom trawl sampling at eight Lake Superior sites during three seasons in 2005 and a subset of sites in 2006. We expected the larger-bodied cisco ( Coregonus artedi ) to exhibit a shallower DVM compared with the smaller-bodied kiyi ( Coregonus kiyi ). Although DVM of kiyi and cisco were consistent with expectations of DVM as a size-dependent, predator-mediated process, we found no relationship between siscowet density and the magnitude of DVM of either coregonid. Cisco appear to have a size refuge from siscowet predation. Kiyi and siscowet co-occur in demersal habitat > 150 m during the day, where visual predation is unlikely, suggesting predator avoidance is not a factor in the daytime distribution of kiyi. Seasonal patterns of kiyi DVM were consistent with reported DVM of their primary prey Mysis relicta . Our results suggest that consideration of nonvisual foraging, rather than light-based foraging theory (i.e., the antipredation window), is necessary to understand the processes driving DVM in deepwater systems.

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.

The schooling and foraging ecology of lake herring (Coregonus artedi) in Lake Opeongo, Ontario, Canada

2005 ◽  
Vol 62 (6) ◽  
pp. 1210-1218 ◽  
Author(s):  
S W Milne ◽  
B J Shuter ◽  
W G Sprules
Keyword(s):  
School Size ◽  
Predator Avoidance ◽  
Linear Dimension ◽  
Lake Trout ◽  
Foraging Ecology ◽  
Salvelinus Namaycush ◽  
Coregonus Artedi ◽  
Schooling Behaviour ◽  
School Formation ◽  
Lake Herring

We used a combination of suspended gill nets and hydroacoustics to investigate the schooling behaviour of lake herring (Coregonus artedi) in Lake Opeongo, Ontario, Canada. Lake herring form schools during the day but are dispersed at night and this change occurs at a light threshold of roughly 0.04 lx. Schools range in maximum linear dimension from 100 to 2300 cm with the majority under 1000 cm. The light threshold for school formation is well below that at which their principal predator, lake trout (Salvelinus namaycush), are able to detect prey. This suggests that schooling may provide advantages in addition to predator avoidance. We observed that lake herring stomachs were fuller during the day than at night, indicating that schooling herring forage more efficiently during the day than individual herring do at night. Furthermore, herring stomach fullness increased with school size, suggesting that schooling enhances foraging opportunities for individual members. We speculate that this is due either to social facilitation of feeding when herring are in the presence of conspecifics, or to corporate vigilance, or "many eyes", which allows individual fish to spend less time being alert to predators and more time feeding.

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.

scholarly journals Food Web Structure Informs Potential Causes of Bimodal Size Structure in a Top Predator

2018 ◽  
Vol 11 (1) ◽  
pp. 36-45 ◽  
Author(s):  
Peter C. Searle ◽  
Joshua A. Verde ◽  
Mark C. Belk
Keyword(s):  
Body Size ◽  
Yellow Perch ◽  
Lake Trout ◽  
Large Body ◽  
Somatic Growth ◽  
Salvelinus Namaycush ◽  
Trophic Niche ◽  
Competitive Interactions ◽  
Large Body Size ◽  
Small Lake

Background: Assemblages of fishes in lakes and reservoirs in the western USA are dominated by non-native, large-bodied, piscivorous fishes that lack a shared evolutionary history. Top predators in these crowded systems are often characterized by unstable population dynamics and poor somatic growth rates. One such assemblage is in Fish Lake, located in southern Utah, USA, in which introduced lake trout (Salvelinus namaycush, Walbaum) exhibit a bimodal growth pattern. A few lake trout in Fish Lake grow rapidly to large size typical of the species; whereas, most never grow beyond 600 mm total length. Objective: To inform competitive interactions in this evolutionarily novel fish assemblage that might cause the low recruitment to large body size in lake trout, we characterized trophic niche (from stable isotope analysis of C and N) of all fishes in the lake. Methods: We used a Bayesian mixing model to describe the trophic niche and infer diet of lake trout and their potential prey, and we used Bayesian ellipse analysis to identify potential areas of high competition within the food web. Large lake trout feed mostly on small lake trout and splake (Salvelinus namaycush, Walbaum x Salvelinus fontinalis, Mitchill) despite availability of abundant yellow perch. (Perca flavescens, Mitchill). Small lake trout and splake feed mostly on zooplankton and exhibit substantial overlap of their trophic niche implying competition for food. Yellow perch and Utah chub (Gila atraria, Girard; formerly an important food item for lake trout in Fish Lake) exhibit extreme overlap of their trophic niche implying strong competitive interactions. Results: Our data suggest that lack of recruitment to large body size in lake trout may result from a reduction in availability of Utah chub resulting from competitive interactions with yellow perch, and increased competition from introduced splake for available prey. Conclusion: Management actions that may help ameliorate the poor somatic growth rates of most lake trout include efforts to reduce perch populations or increase vulnerability of perch to predation by lake trout, and removal of splake as a competitor of small lake trout.

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.

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