Recent Changes in the Aquatic Food Web of Eastern Lake Ontario

1987 ◽  
Vol 44 (S2) ◽  
pp. s37-s52 ◽  
Author(s):  
W. J. Christie ◽  
K. A. Scott ◽  
P. G. Sly ◽  
R. H. Strus
Keyword(s):  
Prey Species ◽  
Lake Trout ◽  
Prey Availability ◽  
Lake Ontario ◽  
Size Composition ◽  
Osmerus Mordax ◽  
Alosa Pseudoharengus ◽  
Rainbow Smelt ◽  
Aquatic Food ◽  
Representative Samples

During the past 10 yr there have been dramatic increases in piscivorous populations of walleye (Stizostedion vitreum) in the Bay of Quinte and of planted lake trout (Salvelinus namaycush) and double-crested cormorants (Phalacrocorax auritus) in the Kingston basin of Lake Ontario. This paper documents changes in the prey stocks shared by these piscivores, including reduction in size and abundance of the slimy sculpin (Cottus cognatus) with subsequent stock equilibration and unabated reduction in the size and abundance of rainbow smelt (Osmerus mordax), both owing to predation pressure from the lake trout. The third primary prey species, alewife (Alosa pseudoharengus), has not yet suffered severely from the depredations of the piscivores. Symptoms of the effects are discernible, however, and the implications of a possible collapse are discussed. Lake trout survival and growth have not yet been affected by the changes in prey availability, but their diet has shifted both in response to their own expanded size composition and relative abundance of the three prey species. Increased utilization of alewife makes the hunting of the trout more pelagic. Problems of obtaining representative samples of the prey are discussed.

Early Life Stage Mortality Syndrome in Fishes of the Great Lakes and Baltic Sea

1998 ◽  
Keyword(s):  
Great Lakes ◽  
Prey Species ◽  
Lake Trout ◽  
Life Stage ◽  
Species Variation ◽  
Osmerus Mordax ◽  
Alosa Pseudoharengus ◽  
Rainbow Smelt ◽  
Thiamine Content ◽  
Lake Variation

<em>Abstract</em>.—Thiamine concentrations in representative Great Lakes prey fish, including alewives <em>Alosa pseudoharengus</em>, rainbow smelt <em>Osmerus mordax</em>, slimy sculpin <em>Cottus cognatus</em>, bloater chub <em>Coregonus hoyi</em>, and lake herring <em>Coregonus artedi</em>, and their major dietary items, including mysids <em>Mysis relicta</em>, amphipods <em>Diporeia hoyi</em>, and net macroplankton, were measured to assess their potential involvement in depressed thiamine concentrations in lake trout <em>Salvelinus namaycush </em>of the Great Lakes. Mean thiamine concentrations in all biota were greater than the recommended dietary intake of 3.3 nmol/g for prevention of effects on growth, although the adequacy of these concentrations for reproduction is not known. Mean thiamine concentrations decreased in the order alewives > bloater chub, herring > smelt and differed from the order of associated egg thiamine concentrations published for lake trout feeding on these species (herring > alewives, smelt). As a result, these data strongly implicate the high thiaminase content, rather than the low thiamine content, of alewives and smelt as being responsible for the low egg thiamine concentrations of Great Lakes lake trout stocks that feed heavily on these species. Variations in thiamine content among prey species did not appear to be related to levels in their diet, because thiamine concentrations in <em>Mysis</em>, <em>Diporeia</em>, and macroplankton showed little consistency between group or between lake variation. There was no lake to lake variation in mean thiamine concentrations of prey species, but considerable within species variation occurred that was unrelated to size.

Dynamics of salmonine diets and foraging in Lake Ontario, 1983-1993: a test of a bioenergetic model prediction

1998 ◽  
Vol 55 (2) ◽  
pp. 307-317 ◽  
Author(s):  
Peter S Rand ◽  
Donald J Stewart
Keyword(s):  
Lake Trout ◽  
Coho Salmon ◽  
Lake Ontario ◽  
Osmerus Mordax ◽  
Alosa Pseudoharengus ◽  
Bioenergetic Model ◽  
Rainbow Smelt ◽  
Predator Species ◽  
Mean Size ◽  
Diet Survey

We tested the hypotheses that (1) reductions in individual size and energy density of adult alewife (Alosa pseudoharengus) in Lake Ontario over the past decade have caused reductions in mean size of consumed alewife and compensatory increases in frequency of feeding by salmonines and (2) perceived recent reductions in the alewife and rainbow smelt (Osmerus mordax) prey base in recent years have resulted in shifts in diets of salmonines to less preferred prey items. Data from a diet survey conducted on sport-caught salmonines during 1983-1988 and 1993 indicated significant reductions in the mean size of consumed alewife across all predator species over time and an increased frequency of feeding among some predators (reflected by a decline in the proportion of empty stomachs observed). We found evidence of increased ration levels in coho salmon (Oncorhynchus kisutch) and lake trout (Salvelinus namaycush) and an increase in the number of adult alewife in stomachs of all predator species that was accurately predicted by an earlier bioenergetic model analysis. We found evidence of a shift in diet across years away from rainbow smelt and other fishes to adult alewife. Results point toward possible sources of bioenergetic stress on salmonines in Lake Ontario.

Planktivory by alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) on microcrustacean zooplankton and dreissenid (Bivalvia: Dreissenidae) veligers in southern Lake Ontario

1995 ◽  
Vol 52 (5) ◽  
pp. 925-935 ◽  
Author(s):  
Edward L. Mills ◽  
Connie Adams ◽  
Robert O'Gorman ◽  
Randall W. Owens ◽  
Edward F. Roseman
Keyword(s):  
Laboratory Experiments ◽  
Lake Ontario ◽  
Osmerus Mordax ◽  
Field Observations ◽  
Alosa Pseudoharengus ◽  
Rainbow Smelt ◽  
Consumption Rates ◽  
South Shore ◽  
Young Of The Year ◽  
Veliger Larvae

The objective of this study was to describe the diet of young-of-the-year and adult alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) in nearshore waters coincident with the colonization of Lake Ontario by Dreissena. Laboratory experiments and field observations indicated that alewife and rainbow smelt consumed dreissenid veligers and that the veligers remained intact and identifiable in the digestive tract for several hours. Dreissenid larvae were found in field-caught alewife and rainbow smelt in August 1992, even though veliger densities were low (<0.1/L). Zooplankton dominated the diet of all fish and veliger larvae were <0.1% of the biomass of prey eaten by these fish. Density of veligers and the distribution of settled dreissenids declined from west to east along the south shore of Lake Ontario. Based on veliger consumption rates we measured and the abundance of veligers and planktivores, we conclude that planktivory by alewife and smelt in the nearshore waters of Lake Ontario did not substantially reduce the number of veligers during 1991–1993. However, our results indicate that if the density of veligers in Lake Ontario decreases, and if planktivores remain abundant, planktivory on veliger populations could be significant.

Mysid and fish zooplanktivory in Lake Ontario: quantification of direct and indirect effects

2006 ◽  
Vol 63 (12) ◽  
pp. 2734-2747 ◽  
Author(s):  
Gideon Gal ◽  
Lars G Rudstam ◽  
Edward L Mills ◽  
Jana R Lantry ◽  
Ora E Johannsson ◽  
...  
Keyword(s):  
Indirect Effects ◽  
Lake Ontario ◽  
Fish Feed ◽  
Osmerus Mordax ◽  
Alosa Pseudoharengus ◽  
Rainbow Smelt ◽  
Mysis Relicta ◽  
Consumption Rates ◽  
Positive Effect ◽  
Potential Rate

Mysis relicta and planktivorous fish feed on zooplankton in Lake Ontario and form a trophic triangle that includes intraguild predation by fish on mysids. Thus, fish affect zooplankton both directly and indirectly. To evaluate the importance of alewife (Alosa pseudoharengus), rainbow smelt (Osmerus mordax), and mysids as zooplanktivores in Lake Ontario, we measured abundances and distributions, assessed diets, and computed mysid and fish consumption rates based on bioenergetics models. We further estimated indirect effects by comparing clearance rates given observed and potential mysid distributions. Estimated consumption rates varied widely with season and water depth and ranged between 2.6 × 10–3 and 1.3 g·m–2·day–1 for mysids and between 1.4 × 10–3 and 0.5 g·m–2·day–1 for fish, representing a daily removal of zooplankton of up to 10.2%·day–1 and 2.0%·day–1 by mysids and fish, respectively. Mysid planktivory exceeded fish planktivory in May and August, but fish planktivory dominated in October. Estimated mysid planktivory rates were 2- to 90-fold lower than the potential rate if mysids moved to temperatures that maximized their predation rates, suggesting an indirect positive effect of fish on zooplankton.

Cercopagis pengoi as a New Prey Item for Alewife (Alosa pseudoharengus) and Rainbow Smelt (Osmerus mordax) in Lake Ontario

2003 ◽  
Vol 29 (2) ◽  
pp. 205-212 ◽  
Author(s):  
Tara M. Bushnoe ◽  
David Michael Warner ◽  
Lars Gösta Rudstam ◽  
Edward L. Mills
Keyword(s):  
Prey Item ◽  
Lake Ontario ◽  
Osmerus Mordax ◽  
Alosa Pseudoharengus ◽  
Rainbow Smelt ◽  
Cercopagis Pengoi

Prey fish exploitation, salmonine production, and pelagic food web efficiency in Lake Ontario

1998 ◽  
Vol 55 (2) ◽  
pp. 318-327 ◽  
Author(s):  
Peter S Rand ◽  
Donald J Stewart
Keyword(s):  
Food Web ◽  
Lake Michigan ◽  
Oncorhynchus Tshawytscha ◽  
Lake Trout ◽  
Coho Salmon ◽  
Lake Ontario ◽  
Osmerus Mordax ◽  
Prey Fish ◽  
Rainbow Smelt ◽  
Time Model

Estimates of production and predation rates from bioenergetic models of chinook salmon (Oncorhynchus tshawytscha), coho salmon (Oncorhynchus kisutch), and lake trout (Salvelinus namaycush) suggest a long-term decline in their gross conversion efficiency (gross production/prey consumption) and the gross production to biomass ratio in Lake Ontario during 1978-1994. The former pattern was caused primarily by a declining trend in adult alewife (Alosa pseudoharengus) energy density during 1978-1985; the latter pattern resulted from reductions in growth rates (coho salmon) and a buildup of the older age-classes in the population (lake trout) over time. Model results suggest that over 100 and 25% of the annual production of adult alewife and rainbow smelt (Osmerus mordax), respectively, was consumed by salmonines during 1990 in Lake Ontario; hence, we claim that recent observations of reduced salmonine growth in Lake Ontario may be a result of prey limitation. Energy transfer from primary production to salmonines appeared to be more efficient in Lake Ontario than in Lake Michigan, probably due to higher stocking levels per unit area and higher densities of preferred prey fish in Lake Ontario. Through separate analyses, we arrived at conflicting conclusions concerning the sustainability of the food web configuration in Lake Ontario during 1990.

Interspecific Relations among Fish Species in South Bay, Lake Huron, 1949–84

1987 ◽  
Vol 44 (S2) ◽  
pp. s10-s14 ◽  
Author(s):  
Bryan A. Henderson ◽  
F. E. J. Fry
Keyword(s):  
Fish Species ◽  
Yellow Perch ◽  
Lake Trout ◽  
Lake Huron ◽  
Osmerus Mordax ◽  
Alosa Pseudoharengus ◽  
White Sucker ◽  
Lake Whitefish ◽  
Rainbow Smelt ◽  
Coregonus Artedii

Of the nine species caught in pound and gill nets in South Bay, Lake Huron (lake whitefish (Coregonus clupeaformis), rainbow smelt (Osmerus mordax), lake trout (Salvelinus namaycush), splake (S. namaycush × S. fontinalis), burbot (Lota lota), lake hering (Coregonus artedii), alewife (Alosa pseudoharengus), white sucker (Catostomus commersoni), and yellow perch (Perca flavescens)), only yellow perch, white sucker, and lake whitefish were significantly related to the abundances of all other fish species (multiple regression) from 1965 to 1984. For the longer period (pound nets 1949–84), all but smelt, burbot, and white sucker were dependent upon variations in the abundance of the nine other species. For the same period (1965–84) and species (nine), the abundances only of yellow perch and white suckers were significantly and positively related in two basins of the Bay. None of the inverse correlations between species abundances was significant in both basins. Within the Outer Basin, only the correlations between alewife and lake herring (r = −0.49, r = −0.45) and yellow perch and white sucker (r = +0.55, r = +0.47) were significant in the same direction for both time periods (1949–64 and 1965–84, respectively). We concluded that there was little evidence that the abundances of species were affected significantly by interspecific influences.

Early Life Stage Mortality Syndrome in Fishes of the Great Lakes and Baltic Sea

1998 ◽  
Keyword(s):  
Great Lakes ◽  
Yellow Perch ◽  
Lake Trout ◽  
Life Stage ◽  
Osmerus Mordax ◽  
Alosa Pseudoharengus ◽  
Rainbow Smelt ◽  
Inland Lakes ◽  
Early Mortality Syndrome ◽  
Thiamine Content

<em>Abstract</em>.—Lake trout <em>Salvelinus namaycush </em>eggs were collected from 18 separate locations in the Great Lakes and inland lakes to evaluate the relationship between diet and egg thiamine content. Thiamine concentrations in the eggs of lake trout whose diet consisted primarily of rainbow smelt <em>Osmerus mordax </em>and alewife <em>Alosa pseudoharengus </em>were one-ninth to one-seventeenth those of eggs of lake trout whose diet lacked either of these two species and was composed of lake herring <em>Coregonus artedi</em>, yellow perch <em>Perca flavescens</em>, cyprinids, or invertebrates. Within the Great Lakes, concentrations of thiamine in the eggs of lake trout increased in the order Ontario, Erie, Michigan, Huron < Superior and reflected the proportion of smelt, alewives, or both in the diet. Of the three forms of thiamine found in eggs, free thiamine was the most important and the form most affected by a diet of alewives or smelt. Collections from inland lakes were similar in terms of thiamine content and its relationship to diet composition. Average free thiamine concentrations in lake trout from Lakes Ontario, Erie, Michigan, and Huron were 1.5 to 4 times a threshold of 0.8 nmol/g that has been associated with the development of a thiamine-responsive early mortality syndrome. In contrast, the concentration of free thiamine in Lake Superior lake trout eggs was 26 times the threshold. We concluded that the reduction in egg thiamine concentrations in lake trout whose diet was primarily smelt or alewives was the result of their high thiaminase content, because published thiamine contents could not explain the patterns observed. Egg thiamine concentrations in lake trout were unaffected by maternal age.

Lake Ontario: Effects of Exploitation, Introductions, and Eutrophication on the Salmonid Community

1972 ◽  
Vol 29 (6) ◽  
pp. 913-929 ◽  
Author(s):  
W. J. Christie
Keyword(s):  
Yellow Perch ◽  
Lake Trout ◽  
White Perch ◽  
Lake Ontario ◽  
Osmerus Mordax ◽  
Alosa Pseudoharengus ◽  
Commercial Catch ◽  
Sequence Of Events ◽  
Catch Statistics ◽  
Average Size

Commercial catch statistics were analyzed to follow the sequence of events in the deterioration of the major fish stocks of Lake Ontario. Atlantic salmon (Salmo salas), lake trout (Salvelinus namaycush), burbot (Lota lota), deepwater ciscoes (Coregonus sp.), and whitefish (Coregonus clupeaformis) have all disappeared or declined seriously in abundance. Only the colonists alewife (Alosa pseudoharengus), smelt (Osmerus mordax) and white perch (Morone americana) are currently abundant. Abundance of deepwater ciscoes is thought to have been controlled originally by the piscivores lake trout and burbot. Three deepwater cisco species are inferred to have been progressively eliminated by overfishing, leaving only the smallest and least valuable present when the fishery collapsed. The effects of the sea lamprey (Petromyzon marinus) on the Lake Ontario fishes are held to have increased with the reduction of the number of dams in the watershed, and as fishing reduced numerical abundance and average size of the prey fishes. The early colonists alewife and carp (Cyprinus carpio) were thought to have stabilized early. It was suggested smelt were suppressed for many years by trout and burbot predation, and after the release of this constraint, the smelt in turn caused the collapse of the deepwater ciscoes and other species through predation. The white perch invasion of the Bay of Quinte was thought particularly swift and successful because of the absence of predators. Yellow perch (Perca flavescens) abundance may have increased because of eutrophication effects in the nearshore areas. Recent deterioration of water quality appears so extreme as to ensure that the last premium species which used the inshore areas cannot return. Overfishing is thought to have been the major destabilizing influence. The role of the open lake predators in the vectoring of energy and materials through the system is discussed.

Using ratios of stable nitrogen and carbon isotopes to characterize the biomagnification of DDE, mirex, and PCB in a Lake Ontario pelagic food web

1995 ◽  
Vol 52 (12) ◽  
pp. 2660-2674 ◽  
Author(s):  
Richard M. Kiriluk ◽  
Mark R. Servos ◽  
D. Michael Whittle ◽  
Gilbert Cabana ◽  
Joseph B. Rasmussen
Keyword(s):  
Stable Isotopes ◽  
Food Web ◽  
Trophic Status ◽  
Lake Trout ◽  
Trophic Position ◽  
Lake Ontario ◽  
Osmerus Mordax ◽  
Rainbow Smelt ◽  
Slimy Sculpin ◽  
Pelagic Food Web

Stable isotopes of nitrogen (δ15N) and carbon (δ13C) were used to describe the trophic status and interactions of biota characteristic of a Lake Ontario pelagic food web. Stable isotopes of nitrogen were further used to characterize the relationship between an organism's trophic position and the biomagnification of specific hydrophobic contaminants through this food web. The δ15N defines the relative trophic status as (i) the top predator, lake trout (Saivelinus namaycush); (ii) prey species, alewife (Alosa pseudoharengus), rainbow smelt (Osmerus mordax), and slimy sculpin (Cottus cognatus); (iii) macroinvertebrates, mysids (Mysis relicta), and amphipods (Diporeia hoyi); (iv) net zooplankton, dominated by cyclopoids (Diacyclops thomasi) and cladocerans (Bosmina longirostris); and (v) net phytoplankton, dominated by diatoms (Melosira spp.). The separation of the four fish species, lake trout and associated prey items (alewife, rainbow smelt, and slimy sculpin), on the basis of their mean δ13C signatures complements what is known about the preferred diet of these fishes. The enrichment of 15N through this food web indicates that there is a strong correlation between the biomagnification of persistent lipophilic contaminants (p,p′-DDE, mirex, and PCB) and the relative trophic status of an organism as described by stable isotopes of nitrogen.

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