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.

Zebra Mussels as Biomonitors for Organic Contaminants in the Lower Great Lakes

1996 ◽  
Vol 31 (2) ◽  
pp. 411-432 ◽  
Author(s):  
Michael E. Comba ◽  
Janice L. Metcalfe-Smith ◽  
Klaus L.E. Kaiser
Keyword(s):  
Great Lakes ◽  
Organic Contaminants ◽  
Lake Erie ◽  
Soft Tissues ◽  
Lake Ontario ◽  
Dry Weight ◽  
Zebra Mussels ◽  
Organic Contamination ◽  
Contamination Levels ◽  
St Lawrence River

Abstract Zebra mussels were collected from 24 sites in Lake Erie, Lake Ontario and the St. Lawrence River between 1990 and 1992. Composite samples of whole mussels (15 sites) or soft tissues (9 sites) were analyzed for residues of organochlo-rine pesticides and PCBs to evaluate zebra mussels as biomonitors for organic contaminants. Mussels from most sites contained measurable quantities of most of the analytes. Mean concentrations were (in ng/g, whole mussel dry weight basis) 154 ΣPCB, 8.4 ΣDDT, 3.5 Σchlordane, 3.4 Σaldrin, 1.4 ΣBHC, 1.0 Σendosulfan, 0.80 mirex and 0.40 Σchlorobenzene. Concentrations varied greatly between sites, i.e., from 22 to 497 ng/g for ΣPCB and from 0.08 to 11.6 ng/g for ΣBHC, an indication that mussels are sensitive to different levels of contamination. Levels of ΣPCB and Σendosulfan were highest in mussels from the St. Lawrence River, whereas mirex was highest in those from Lake Ontario. Overall, mussels from Lake Erie were the least contaminated. These observations agree well with the spatial contaminant trends shown by other biomoni-toring programs. PCB congener class profiles in zebra mussels are also typical for nearby industrial sources, e.g., mussels below an aluminum casting plant contained 55% di-, tri- and tetrachlorobiphenyls versus 31% in those upstream. We propose the use of zebra mussels as biomonitors of organic contamination in the Great Lakes.

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

scholarly journals Toxic elements in free-living freshwater fish, water and sediments in Poland

2014 ◽  
Vol 58 (4) ◽  
pp. 589-595 ◽  
Author(s):  
Józef Szkoda ◽  
Jan Żmudzki ◽  
Agnieszka Nawrocka ◽  
Mirosława Kmiecik
Keyword(s):  
River Sediments ◽  
River Estuary ◽  
Absorption Spectrometry ◽  
Dry Weight ◽  
Fish Muscle ◽  
Average Concentration ◽  
Predatory Fish ◽  
Quality Assurance Programme ◽  
Lead And Cadmium ◽  
Vistula River

Abstract Samples for analysis were collected from 10 areas, including the major Polish rivers and lakes, with different sources of environmental pollution (industrial, municipal, and farming). The materials was taken from the lakes of Mazury, located in a non-industrialised region, from the Brda River, an area impacted by pig farms, from the lakes of Lipczyno Wielkie/Pomerania, from the Wkra River, an area impacted by poultry farms, from the Dunajec River at the Roznowski Reservoir, from the Vistula River at Cracow and Warsaw, from the Odra River at Wroclaw and the Warta River estuary, and also from Rybnik Power Station Reservoir. Concentrations of Pb, Cd, Hg, and As were analysed in 397 fish muscle and 128 sediment samples using an atomic absorption spectrometry technique. The analytical procedures were covered by a quality assurance programme. It was demonstrated that the average concentrations of lead, cadmium, and arsenic in fish were in the low hundredths and thousandths of a mg/kg and never exceeded permitted limits established for food. Higher values of these elements were found in fish from bodies of water located in the zone of influence of large urban agglomerations, especially the Cracow region. High concentrations of lead and cadmium were also found in Vistula River sediments near Cracow, where the maximum values were 134.10 mg/kg and 21.24 mg/kg dry weight for lead and cadmium respectively. The average concentration of mercury in a predatory fish muscle (0.179 mg/kg) was almost twice as high as in the omnivorous fish (0.103 mg/kg). Only a single fish sample exceeded the maximum limit for this metal (0.50 mg/kg) and did not present a risk to consumers’ health.

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.

The ensilage of sorghum at a range of crop maturities

1962 ◽  
Vol 2 (5) ◽  
pp. 101 ◽  
Author(s):  
VR Catchpoole
Keyword(s):  
Protein Content ◽  
Crude Protein ◽  
Dry Weight ◽  
Crude Protein Content ◽  
Booting Stage ◽  
Physical Conditions ◽  
Moisture Contents ◽  
Produce Acid

This study, using miniature silos, bas shown that sorghum cut at the booting stage can produce acid silage. Such early harvesting produced silage with a crude protein content of 10 per cent of its dry weight, did not significantly reduce the yield per acre of silage protein, but reduced the yield of silage by some 40 per cent. Sorghum cut before the booting stage failed to produce satisfactory acid silage. Thic could not he explained by low initial sugar contents. Also, a comparison of the fermentation behaviour over the range of crop maturities in miniature silos and water slurries suggests that physical conditions, such as moisture contents and the release of cell constituents, had little influence on the development of acidity.

Distribution and transformation of elemental mercury in the St. Lawrence River and Lake Ontario

2000 ◽  
Vol 57 (S1) ◽  
pp. 155-163 ◽  
Author(s):  
Marc Amyot ◽  
David RS Lean ◽  
Laurier Poissant ◽  
Marie-Renée Doyon
Keyword(s):  
Water Column ◽  
Laboratory Experiments ◽  
Lake Ontario ◽  
Elemental Mercury ◽  
Volatile Species ◽  
Spatial And Temporal Patterns ◽  
First Order ◽  
Inland Lakes ◽  
First Order Kinetics ◽  
St Lawrence River

Elemental Hg (Hg0) is a volatile species that is responsible for water-to-air transfer of Hg in Lake Ontario and the St. Lawrence River. We conducted two cruises in 1998 to identify spatial and temporal patterns in Hg0 levels in these systems and performed field and laboratory experiments on redox transformations of Hg. Elemental Hg concentrations were higher in Lake Ontario than in the St. Lawrence River. At stations in Lake Ontario, Hg0 levels were higher at the bottom of the water column than at the surface, whereas they were homogeneous throughout the water column of the river. Elemental Hg concentrations were generally higher in July than in September and, in contrast with experiments on inland lakes, were relatively constant during the day except for a narrow peak at sunrise. Field and laboratory experiments showed that photoreduction of Hg(II) in St. Lawrence River water was substrate limited and was influenced by visible and ultraviolet radiation. Pseudo first-order kinetics best described photoreduction, with k values between 1 and 2·h-1.

Particle-Size-Conversion Efficiency and Contaminant Concentrations in Lake Ontario Biota

1983 ◽  
Vol 40 (3) ◽  
pp. 328-336 ◽  
Author(s):  
Uwe Borgmann ◽  
D. M. Whittle
Keyword(s):  
Particle Size ◽  
Body Size ◽  
Conversion Efficiency ◽  
Food Chain ◽  
Lake Ontario ◽  
Dry Weight ◽  
Growth Efficiency ◽  
Fish Production ◽  
The Relationship ◽  
Zooplankton Production

The particle-size-conversion efficiency (log food consumption/production divided by log predator prey size ratio) is shown to be directly related to the relationship between the concentration of persistent contaminants accumulated primarily through the food chain and body size for organisms in pelagic ecosystems. The difference between particle-size-conversion efficiency for biomass and that for the contaminant gives the slope of the relationship between log contaminant concentration and log body size. This provides a useful theoretical framework for analyzing contaminant concentrations in aquatic biota without the need for specifying trophic level but still incorporating the idea of food chain accumulation. Concentrations of PCB, DDT, and mercury were examined in aquatic organisms from Lake Ontario, ranging in size from zooplankton to large salmonids (a 108 -fold range in dry weight). The slope of the double log plot of concentration versus weight varied from 0.20 to 0.22 for PCB and DDT and was approximately equal to 0.13 for mercury. This indicates that mercury is accumulated less efficiently through the food chain than PCB or DDT. After correcting for incomplete uptake and retention of the contaminant, an estimate of particle-size-conversion efficiency for biomass of about 0.26 was obtained, which agrees reasonably well with previous estimates obtained from growth efficiency experiments and analysis of particle-size spectra. These calculations indicate that potential fish production in Lake Ontario is ~ 120-fold lower than zooplankton production (for fish averaging 108-fold larger in body size as compared to zooplankton).Key words: particle-size-conversion efficiency, PCB, DDT, mercury, zooplankton production, fish production

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