Particle-size-conversion Efficiency, Invertebrate Production, and Potential Fish Production in Lake Ontario

Borgmann, Uwe; Whittle, D. Michael

doi:10.1139/f94-069

Cited by 8 publications

(5 citation statements)

References 21 publications

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“…Previous studies have typically considered mysid consumption of zooplankton separate and secondary to planktivorous fish consumption of zooplankton (Rand et al 1995). Accordingly, studies have grouped mysids with zooplankton when discussing trophic interactions of the Lake Ontario food web (Borgmann and Whittle 1994;Sprules and Goyke 1994). In contrast, our results indicate that mysid predation on zooplankton is comparable with and exceeds that exerted by alewife and rainbow smelt during the spring and summer.…”

Section: Discussioncontrasting

confidence: 55%

“…Previous studies of Lake Ontario trophic interactions between planktivores and zooplankton have typically combined zooplankton and mysid production as a pooled resource available to planktivores in the lake (Borgmann and Whittle 1994;Sprules and Goyke 1994;Rand et al 1995). These studies have not usually accounted for the impact of mysid predation on zooplankton populations.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Gal¹,

Rudstam²,

Mills³

et al. 2006

Can. J. Fish. Aquat. Sci.

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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.Résumé : Dans le lac Ontario, Mysis relica et les poissons planctonophages se nourrissent de zooplancton et forment ainsi un triangle trophique qui inclut la prédation par des membres de la guilde des poissons sur les mysidacés. Les poissons affectent donc le zooplancton à la fois directement et indirectement. Afin d'évaluer l'importance de la consommation de zooplancton par le gaspareau (Alosa pseudoharengus), l'éperlan arc-en-ciel (Osmerus mordax) et les mysidacés, nous avons mesuré les abondances et les répartitions, déterminé les régimes alimentaires et calculé les taux de consommation des mysidacés et des poissons d'après des modèles bioénergétiques. Nous avons estimé, de plus, les effets indirects en comparant les taux de clearance, compte tenu des répartitions observées et potentielles des mysidacés. Les taux de consommation estimés varient considérablement en fonction de la saison et de la profondeur de l'eau: ils vont de 2,6 × 10 -3 à 1,3 g·m -2 ·jour -1 chez les mysidacés et de 1,4 × 10 -3 à 0,5 g·m -2 ·jour -1 chez les poissons, ce qui correspond à des retraits quotidiens du zooplancton respectifs de jusqu'à 10,2 % par jour et de 2,0 % par jour. La consommation de plancton par les mysidacés dépasse celle des poissons en mai et en août, mais celle effectuée par les poissons domine en octobre. Les taux estimés de consommation du plancton par les mysidacés sont 2-90 fois plus faibles que les taux potentiels que l'on obtiendrait si les mysidacés se déplaçaient vers les températures qui maximisent leur taux de prédation; il semble donc y avoir un effet indirect positif des poissons sur le zooplancton.[Traduit par la Rédaction] Gal et al. 2747

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Section: Discussioncontrasting

confidence: 55%

Section: Introductionmentioning

confidence: 99%

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

Gal¹,

Rudstam²,

Mills³

et al. 2006

Can. J. Fish. Aquat. Sci.

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“…Since a Lake Trout uses approximately 72% of its thiamine prior to hatching (Jaroszewska et al 2009), a newly hatched fry requires 0.028 nmol of thiamine. The range of thiamine in individual copepods, Bosmina, and Daphnia (the most common items in fry stomachs from this study) is 2.2 £ 10 ¡6 to 1.5 £ 10 ¡3 nmol per plankton (thiamine data from Hutchinson 1943; dry weights from Watkins et al 2011; wet weight conversions from Borgmann and Whittle 1994). To acquire 0.028 nmol of thiamine, fry would need to consume only 19 of the largest zooplankton to offset acute thiamine deficiency.…”

Section: Discussionmentioning

confidence: 83%

Early Feeding by Lake Trout Fry

2015

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The restoration of Lake Trout Salvelinus namaycush in the Great Lakes and Lake Champlain has been challenging due to the bottlenecks in recruitment that occur mostly during early life stages. Among possible sources of fry mortality (e.g., predation, starvation, and disease), the least is known about the diet and starvation risk of pre-emergent fry. The first feedings by fry are generally assumed to be delayed until close to the absorption of the yolk sac and the emergence of the fry. The stomach contents of 374 wild-caught Lake Trout fry from Lake Champlain were examined from hatching to the exogenous feeding stage to identify the earliest occurrence of feeding relative to yolk sac absorption and to describe the diet. Within 2 weeks of hatching, 19% of fry had food in their stomachs. At 4-6 weeks and after yolk sac absorption, 98% of fry began feeding. Diet was primarily comprised of Bosmina as well as calanoid and cyclopoid copepods, and fry contained up to 215 items per stomach. Our finding that fry began feeding within 2 weeks of hatching (prior to yolk sac absorption) is relevant to current concerns that Lake Trout fry mortality in the Great Lakes is caused by thiamine deficiency syndrome: wild Lake Trout fry may be able to mitigate thiamine deficiency with early feeding on thiamine-rich zooplankton.

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“…Lower alewife growth rates are predicted to affect lake trout PCB concentrations more than concentrations in chinook salmon or steelhead. Continued reductions in P loading to Lake Ontario have been hypothesized to result in decreases in growth rates of fish at all levels of the pelagic food web ( − ). The greater effect on lake trout is consistent with their lower growth rate and higher PCB assimilation efficiency.…”

Section: Discussionmentioning

confidence: 99%

“…Continued reductions in P loading to Lake Ontario have been hypothesized to result in decreases in growth rates of fish at all levels of the pelagic food web (28)(29)(30). Continued reductions in P loading to Lake Ontario have been hypothesized to result in decreases in growth rates of fish at all levels of the pelagic food web (28)(29)(30).…”

Section: Lake Ontario Model Predictions (Year 2005) Of Biomass and Pcmentioning

confidence: 99%

How Will Decreased Alewife Growth Rates and Salmonid Stocking Affect Sport Fish PCB Concentrations in Lake Ontario?

Jackson

1996

Environ. Sci. Technol.

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Atmospheric deposition and resuspension from pelagic sediments are the two principal PCB sources to Great Lakes pelagic food webs today. The expansive nature of these sources makes their management and control impractical. Fisheries management, such as the numbers and species of salmonids stocked, represents a potential mechanism by which PCB concentrations in sport fish may be further reduced. I used a simulation model to examine the effect of alewife growth rates, alewife PCB concentrations, and stocking scenarios on sport fish PCB concentrations over the next decade. Eliminating lake trout is predicted to have little effect on growth rates and PCB concentrations of the remaining salmonids. However, eliminating chinook salmon will maximize growth rates of the remaining species and is predicted to lead to a 15% decline in lake trout PCB concentrations. If alewife growth rates decline, sport fish growth rates will also decline, and their PCB concentrations will increase. Reduced salmonid stocking carries the risk that alewife survival may increase, leading to a greater number of older and more contaminated alewife. If the average alewife consumed went from an age class 3+ to a 6+ fish, sport fish PCB concentrations are predicted to increase by 40% (lake trout) to 60% (chinook salmon and steelhead). Thus, prey PCB concentrations are likely to play a more important role than salmonid growth rates in determining salmonid PCB concentrations.

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Particle-size-conversion Efficiency, Invertebrate Production, and Potential Fish Production in Lake Ontario

Cited by 8 publications

References 21 publications

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

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

Early Feeding by Lake Trout Fry

How Will Decreased Alewife Growth Rates and Salmonid Stocking Affect Sport Fish PCB Concentrations in Lake Ontario?

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