Predation on Mysis relicta by Slimy Sculpins (Cottus cognatus) in Southern Lake Ontario

1995 ◽  
Vol 21 (2) ◽  
pp. 275-283 ◽  
Author(s):  
Randall W. Owens ◽  
Peter G. Weber
Keyword(s):  
Lake Ontario ◽  
Mysis Relicta ◽  
Cottus Cognatus

Mysis relicta in Lake Ontario:

2003 ◽  
pp. 257-288
Author(s):  
O.E. Johannsson ◽  
L.G. Rudstam ◽  
G. Gal ◽  
E.L. Mills
Keyword(s):  
Lake Ontario ◽  
Mysis Relicta

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.

Response of Mysis relicta population dynamics and productivity to spatial and seasonal gradients in Lake Ontario

1995 ◽  
Vol 52 (7) ◽  
pp. 1509-1522 ◽  
Author(s):  
Ora E. Johannsson
Keyword(s):  
Lake Ontario ◽  
Size Composition ◽  
Dry Weight ◽  
Predatory Fish ◽  
Female Size ◽  
Spatial And Temporal Patterns ◽  
Horizontal Movement ◽  
Mysis Relicta ◽  
Physical Conditions ◽  
Depth Relationship

Spatial and temporal patterns of production, density, reproductive status, and size composition of Mysis relicta in Lake Ontario were analyzed in relation to predation and physical conditions. Two whole-lake (May, November) surveys and one partial (August) survey were conducted in 1990. Spatial patterns were related to lake depth. Abundance increased with depth of sampling stations, particularly between 20 and 100 m. At station depths >100 m, the percentage of females carrying eggs and mean female size were constant, but the number of eggs per female increased with station depth. During the winter, the density–depth relationship weakened, apparently through the action of storms and currents, but strengthened again during the summer. Mysids >9 mm in length tended to move to deeper water during the summer. The distributions of predatory fish (alewife, smelt, and sculpin) suggest that depth-related patterns in the mysid population may be due to differences in predation rates with depth and season as well as to horizontal movement. Whole-lake production was estimated to be between 412.91 and 506.82 × 108 g dry weight: most production occurred between 100 and 200 m depth. Growth rate was similar in all regions of the lake.

Oxygen consumption during simulated vertical migration in Mysis relicta (Crustacea, Mysidacea)

1976 ◽  
Vol 54 (3) ◽  
pp. 377-385 ◽  
Author(s):  
J. B. Foulds ◽  
J. C. Roff
Keyword(s):  
Oxygen Consumption ◽  
Swimming Speed ◽  
Vertical Migration ◽  
Lake Ontario ◽  
Dry Weight ◽  
Mysis Relicta ◽  
Migration Rates ◽  
Beat Rate ◽  
External Salinity

When Mysis relicta was induced to swim at speeds of 1.0 and 1.6 cm/s, which are similar to observed vertical migration rates in Lake Ontario, there was no significant (P <.05) increase in oxygen consumption over the 'routine' rate of 5.28 μg oxygen per animal per hour for a 5-mg animal (dry weight). At higher swimming speeds (2.1 to 3.6 cm/s) an increase in oxygen consumption to 1.2 times the 'routine' rate was demonstrated. Exopodite beat rate increased from 3.7 cycles per second under 'routine' conditions to 5.3 cycles per second al a swimming speed of 3.6 cm/s. Increased external salinity under 'routine' conditions resulted in decreased rates of oxygen consumption from 5.28 μg oxygen per animal per hour at 0‰, to 3.28 μg oxygen per animal per hour at 15‰ for a 5-mg animal. At 25‰ and 30‰, oxygen consumption remained about the same as at 15‰. The results add further support to earlier theories that postulate a negligible "cost" for vertical migration.

Predicting the vertical distribution of the opossum shrimp, Mysis relicta, in Lake Ontario: a test of laboratory-based light preferences

2009 ◽  
Vol 66 (1) ◽  
pp. 101-113 ◽  
Author(s):  
Brent T. Boscarino ◽  
Lars G. Rudstam ◽  
Ellis R. Loew ◽  
Edward L. Mills
Keyword(s):  
Vertical Distribution ◽  
Thermal Conditions ◽  
Lake Ontario ◽  
Equal Weight ◽  
Mysis Relicta ◽  
Vertical Movements ◽  
Light Levels ◽  
Preference Functions ◽  
The Vertical Distribution ◽  
Mysid Shrimp

Light and temperature strongly influence the vertical distribution of the mysid shrimp, Mysis relicta . We monitored the vertical movements and depth selection behavior of mysids exposed to different light intensities and light–temperature gradients in the laboratory and derived a mysid light preference function in units relevant to mysid vision: “mylux”. Mysids preferred light levels between 10−8 and 10−7 mylux (∼10−6 to 10−5 lux) and rarely moved into waters of 10−3 mylux (∼0.1 lux) and greater. A model that assumed equal weight and independence of mysid light and temperature preference functions successfully predicted the proportion of mysids found in two different temperature–light combinations in the laboratory. This model also predicted the depth of maximum mysid density to within 2 m on two spring nights and within 5 m on two summer nights of varying moon phase and thermal conditions in Lake Ontario. This study provides novel insights into how temperature and light interact to influence the vertical distribution of mysids. Our model may be used to predict mysid vertical distribution in any deepwater system inhabited by mysids in which the primary mysid predators are visual feeders.

Diet of Mysis relicta in Lake Ontario as revealed by stable isotope and gut content analysis

2001 ◽  
Vol 58 (10) ◽  
pp. 1975-1986 ◽  
Author(s):  
Ora E Johannsson ◽  
Mike F Leggett ◽  
Lars G Rudstam ◽  
Mark R Servos ◽  
M Ali Mohammadian ◽  
...  
Keyword(s):  
Content Analysis ◽  
Stable Isotope ◽  
Isotope Analysis ◽  
Lake Ontario ◽  
Gut Content Analysis ◽  
Gut Content ◽  
Daily Consumption ◽  
Mysis Relicta ◽  
Dietary Knowledge ◽  
Key Species

Stable isotope analysis of the potential prey and predator can be combined with gut content analysis to quantify the diet. This dietary knowledge allows the quantitative assessment of the role of key species in energy and contaminant transfer, their impact on prey communities, and their susceptibility to perturbation. The diet of Mysis relicta was examined in Lake Ontario in spring, summer, and autumn using both techniques. Mysids fed on the bottom during the day and in the pelagia and on the bottom at night. A trophic fractionation of 2.2‰ N between mysids and their prey provided the best correspondence between the observed stable isotope signature of mysids and that estimated from their diet. Tissue turnover rate of δ13C was slow compared with that of δ15N. Diatoms formed 50% of the assimilated diet in May. In September, 25% of large mysids feeding on the bottom contained amphipod parts and 20% contained phytoplankton. The remainder of the diet consisted of zooplankton and rotifers. The contribution of amphipods and phytoplankton could not be quantified. Revised daily consumption estimates, based on this new diet information and clearance rate estimates of consumption, gave daily consumption estimates similar to those estimated from previous bioenergetic modelling.

scholarly journals Quantifying acoustic survey uncertainty using Bayesian hierarchical modeling with an application to assessing Mysis relicta population densities in Lake Ontario

2016 ◽  
Vol 73 (8) ◽  
pp. 2104-2111 ◽  
Author(s):  
Patrick J. Sullivan ◽  
Lars G. Rudstam
Keyword(s):  
Hierarchical Modeling ◽  
Survey Design ◽  
Lake Ontario ◽  
Sensitivity Analyses ◽  
Target Strength ◽  
Parameter Estimates ◽  
Data Set ◽  
Density Estimates ◽  
Mysis Relicta ◽  
Bayesian Hierarchical

Abstract A Bayesian hierarchical model was applied to acoustic backscattering data collected on Mysis relicta (opossum shrimp) populations in Lake Ontario in 2005 to estimate the combined uncertainty in mean density estimates as well as the individual contributions to that uncertainty from the various information sources involved in the calculation including calibration, target strength determination, threshold specification and survey sampling design. Traditional estimation approaches often only take into account the variability associated with the survey design, while assuming that all other intermediate parameter estimates used in the calculations are fixed and known. Unfortunately, unaccounted for variation in the steps leading up to the global density estimate may make significant contributions to the uncertainty of density estimates. While other studies have used sensitivity analyses to demonstrate the degree to which uncertainty in the various input parameters can influence estimates, including the uncertainty directly as demonstrated here using a Bayesian hierarchical approach allows for a more transparent representation of the true uncertainty and the mechanisms needed for its reduction. A Bayesian analysis of the mysid data examined here indicates that increasing the sample size of biological collections used in the target strength regression prove to be a more direct and practical way of reducing the overall variation in mean density estimates than similar steps employed to increase the number of transects surveyed. A doubling of target strength net tow samples resulted in a 23% reduction in variance relative to an 11% reduction that resulted from doubling the number of survey transects. This is an important difference as doubling the number of survey transects would add 5 days to the survey whereas doubling the number of net tows would add only one day. Although these results are specific to this particular data set, the method described is general.

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