Vertical Distribution and Seasonal Abundance of Zooplankton in Two Shallow Lakes of the Experimental Lakes Area, Northwestern Ontario

1971 ◽  
Vol 28 (2) ◽  
pp. 245-256 ◽  
Author(s):  
D. W. Schindler ◽  
Bengt Novén
Keyword(s):  
Vertical Distribution ◽  
Dry Weight ◽  
Distribution Patterns ◽  
Zooplankton Biomass ◽  
Seasonal Abundance ◽  
Experimental Lakes Area ◽  
Leptodora Kindtii ◽  
Northwestern Ontario ◽  
Vertical Distributions ◽  
Diurnal Movement

Seasonal variations in the abundance of zooplankton were studied in lakes 122 and 132 for a period of 10 months beginning in mid-May 1968. Seasonal dynamics of various species are discussed in relation to their patterns in the Canadian Shield and in other localities.Day and night vertical distributions for each lake were sampled on two dates in summer. Three species of rotifers migrated diurnally in lake 122, but no evidence of diurnal movement was found in lake 132. All crustaceans studied in both lakes migrated vertically to some degree, except for nauplius larvae and Leptodora kindtii. There was little difference in vertical distribution patterns on the two dates studied.Average zooplankton biomass in the two lakes was calculated and compared with that found in other studies. Average zooplankton biomass during the ice-free season was 72 and 156 mg/m3 dry weight for lakes 122 and 132, respectively. Dominant species in both lakes were Diaptomus minutus, Cyclops bicuspidatus thomasi, Holopedium gibberum, and Bosmina longirostris. Ecological tolerances for rotifer species agreed well with those found for Swedish waters.

scholarly journals Vertical distribution of pre-settled sandeel (Ammodytes marinus) in the North Sea in relation to size and environmental variables

2003 ◽  
Vol 60 (6) ◽  
pp. 1342-1351 ◽  
Author(s):  
Henrik Jensen ◽  
Peter J Wright ◽  
Peter Munk
Keyword(s):  
Vertical Distribution ◽  
Water Column ◽  
North Sea ◽  
Distribution Patterns ◽  
Food Concentration ◽  
The North ◽  
Vertical Distributions ◽  
The North Sea ◽  
Drift Trajectory ◽  
Vertical Positioning

Abstract Vertical distribution patterns of larval and juvenile sandeels were investigated at four locations in the North Sea. Sandeels between 6 and 65 mm were found to depths of 80 m, with vertical distributions dependent on both length and environmental factors. At one location with a stratified water column, the highest densities were found during the day in midwater where food concentration was also highest. In areas without marked vertical hydrographic gradients, larvae were relatively more abundant in surface waters during the day. At all locations, larvae of all sizes were generally more homogeneously distributed in the water column during night than during day. The extent of vertical migration, as measured by the standard deviation of the mean depth, increased generally with length. Gear avoidance was evident for larvae ≥20 mm. Catch efficiency generally depended on both length class and surface light intensity. A simulated drift pattern of larvae, based on ADCP current measurements from two locations, predicts that the horizontal drift trajectory would only be affected slightly by the vertical positioning of the larvae in the water column during the time of sampling. The implication of vertical migrations for dispersal of larvae away from the spawning grounds is discussed.

Diel vertical distribution of fish larvae during the winter-mixing period in the Northwestern Mediterranean

2004 ◽  
Vol 61 (8) ◽  
pp. 1243-1252 ◽  
Author(s):  
A. Sabatés
Keyword(s):  
Vertical Distribution ◽  
Water Column ◽  
Fish Species ◽  
Fish Larvae ◽  
Distribution Patterns ◽  
Diel Variation ◽  
Surface Layers ◽  
Light Levels ◽  
Vertical Distributions ◽  
The Vertical Distribution

Abstract The vertical distributions of the larvae of shelf and oceanic fish species that spawn during the winter-mixing period in the Mediterranean are described from 22 vertically stratified plankton tows. Diel differences in the vertical distribution patterns in relation to physical data and potential prey abundance throughout the water column were examined. Even in absence of stratification, the larvae of the various fish species showed different patterns of vertical distribution and diel changes. The larvae of shelf-dwelling species were found in the surface layers, mainly above 50-m depth, and with some exceptions, with very little diel variation in depth distribution. Therefore, the vertical distribution of the larvae of these species coincided with the maximum concentrations of their potential food, nauplii and copepodite stages of copepods. The larvae of mesopelagic fishes showed deeper distributions in the water column and most of these species were located closer to the surface during the day than at night. Given the homogeneity of the physical characteristics throughout the water column, except for light, this behaviour may be determined not only by the higher concentration of prey in the surface layers but also by adequate light levels for feeding.

Horizontal and vertical distribution patterns, retention rates, and population dynamics of zooplankton on Western Bank, Scotian Shelf

2003 ◽  
Vol 60 (10) ◽  
pp. 1229-1244 ◽  
Author(s):  
Christian S Reiss ◽  
Ian A McLaren ◽  
Patricia Avendaño
Keyword(s):  
Population Dynamics ◽  
Vertical Distribution ◽  
Spatial Scales ◽  
Distribution Patterns ◽  
Zooplankton Biomass ◽  
Retention Rates ◽  
Local Production ◽  
Scotian Shelf ◽  
Particle Retention ◽  
Horizontal And Vertical Distribution

We assess the importance of retention rates and local production to the concentration of zooplankton on Western Bank, Scotian Shelf, during September and October 1998. We do so using (i) particle retention rates derived from an array of 25 current meters and inferences from hydrographic structure; (ii) observations on the horizontal and vertical distribution of zooplankton and ichthyoplankton; and (iii) a simple projection-matrix model of the population dynamics of two copepod species, Centropages typicus and Pseudocalanus spp. Zooplankton biomass and adult stages of copepods were more abundant in surface waters on the bank (p < 0.05) at broad (25 km) spatial scales. Zooplankton was correlated with ichthyoplankton abundance at this scale (r > 0.5, p < 0.001), a result of local production of both zooplankton and fish on the bank. The time-dependent anticyclonic circulation around Western Bank was variable, and particle retention rates were 18 and 33% for 20 days at 12.5 and 28.5 m, respectively. The population model showed that both C. typicus and Pseudocalanus spp. are capable of increasing their population size despite advective loss and mortality rates approaching 10%·day-1. We conclude that local production exceeding advective loss rates can explain the high concentrations of zooplankton on Western Bank.

Changes in methyl mercury concentrations in zooplankton from four experimental reservoirs with differing amounts of carbon in the flooded catchmentsThis paper is part of the series “Forty Years of Aquatic Research at the Experimental Lakes Area”.

2009 ◽  
Vol 66 (11) ◽  
pp. 1910-1919 ◽  
Author(s):  
Britt D. Hall ◽  
Katharine A. Cherewyk ◽  
Michael J. Paterson ◽  
R. (Drew) A. Bodaly
Keyword(s):  
Food Web ◽  
Methyl Mercury ◽  
Dry Weight ◽  
Experimental Lakes Area ◽  
Organic C ◽  
Dissolved Organic C ◽  
Northwestern Ontario ◽  
Highly Correlated ◽  
Source Waters

Methyl mercury (MeHg) concentrations in zooplankton were compared from four experimental reservoirs at the Experimental Lakes Area in northwestern Ontario, Canada, to test the hypothesis that increases in concentrations of MeHg in zooplankton would be proportional to C availability. The experimental reservoirs included three upland reservoirs flooded between 1999 and 2003 that differed in amounts of flooded organic terrestrial C (high, medium, and low C) and an experimental reservoir created over a wetland–peatland complex in 1993. After flooding, MeHg in zooplankton increased from <100 ng·g dry weight–1 in inflow source waters to >500 ng·g dry weight–1 in all reservoirs. In the first two years of flooding, MeHg in zooplankton was not correlated with amounts of flooded C, but the rates of decline in mean annual concentrations were negatively correlated with the amount of C stored in flooded catchments. Concentrations of MeHg in zooplankton were highly correlated with MeHg concentrations in unfiltered water, with reductions in bioaccumulation associated with increases in dissolved organic C and decreases in pH. Overall, our results suggest that reservoir designs that minimize the amount of flooded terrestrial C should result in shorter periods of elevated MeHg in the food web.

Chemistry of Surface Sediments of Sixteen Lakes in the Experimental Lakes Area, Northwestern Ontario

1971 ◽  
Vol 28 (2) ◽  
pp. 277-294 ◽  
Author(s):  
G. J. Brunskill ◽  
D. Povoledo ◽  
B. W. Graham ◽  
M. P. Stainton
Keyword(s):  
Lake Sediments ◽  
Lake Sediment ◽  
Chemical Weathering ◽  
Major Ions ◽  
Fine Fraction ◽  
Dry Weight ◽  
Terrestrial Vegetation ◽  
Experimental Lakes Area ◽  
Sediment Samples ◽  
Northwestern Ontario

This paper contains some descriptive chemical data on bedrock, soils, and profundal lake sediments of the Experimental Lakes Area (ELA). The acid granodiorite bedrock and the plagioclase–K-feldspar–quartz glacial drift of the region exhibit low rates of chemical weathering. Terrestrial vegetation, soil organic matter, and the fine fraction of the glacial drift are concentrated in the lake sediments. The major minerals of the lake sediments are quartz, plagioclase, K-feldspar, illite, chlorite, kaolinite. Loss on ignition for the lake sediment samples varies from 18 to 62% dry weight, organic carbon from 8 to 34% dry weight, total nitrogen from 0.9 to 3.5% dry weight, and total phosphorus from 0.1 to 0.3% dry weight. These surficial lake sediment samples are 88–96% water, and concentrations of major ions in sediment interstitial water are 1.5–5 times the concentration of major ions in lake water.

Vertical Distribution of Threecornered Alfalfa Hopper Nymphs (Homoptera: Membracidae) and Girdles on Soybean

1992 ◽  
Vol 27 (4) ◽  
pp. 317-324
Author(s):  
Dale W. Spurgeon ◽  
A. J. Mueller
Keyword(s):  
Vertical Distribution ◽  
Distribution Patterns ◽  
Plant Phenology ◽  
Main Stem ◽  
Growth Stages ◽  
Vertical Distributions ◽  
Whole Plants ◽  
Spissistilus Festinus ◽  
Middle Strata ◽  
Lower Plant

The vertical distributions of Spissistilus festinus (Say) instars, petiole girdles, and main stem girdles on soybean, Glycine max (L.) Merrill, were investigated by inspecting randomly selected whole plants. Vertical distribution patterns were characterized by dividing sampled plants into three strata: lower (the lower main stem), middle (the lower half of the canopy), and upper (the upper half of the canopy). Most nymphs were located in lower strata on plants of growth stages V2 through V7 and in middle strata on more developed plants. First and fifth instars tended to be distributed higher than third and fourth instars on plants of growth stage ≥ V10. Most main stem girdles occurred in lower plant strata regardless of plant phenology. Petiole girdles were distributed similarly to nymphs except for a scarcity in lower plant strata. Although plant phenology appeared to affect nymphal vertical distribution few nymphs or girdles were ever located in the upper plant canopy.

Relationships Between Dipteran Emergence and Phytoplankton Production in the Experimental Lakes Area, Northwestern Ontario

1980 ◽  
Vol 37 (3) ◽  
pp. 523-533 ◽  
Author(s):  
I. J. Davies
Keyword(s):  
Euphotic Zone ◽  
Dry Weight ◽  
Single Equation ◽  
Phosphorus Loading ◽  
Phytoplankton Production ◽  
Lake Depth ◽  
Lake Productivity ◽  
Experimental Lakes Area ◽  
Surface Distribution ◽  
Northwestern Ontario

Dipteran emergence was monitored at the Experimental Lakes Area (ELA) between 1973 and 1977 in seven lakes of different trophic status. The data were used to develop a number of equations which related the quantity and spatial distribution of average annual emergence to lake productivity. These models explained > 94% of the variation in mean emergent biomass among lakes or > 76% of the variation in numbers of emergent Diptera in terms of phytoplankton production or phosphorus loading. On average, ELA lakes produced 40.8 dipteran adults (9 mg dry weight) per gram carbon fixed by phytoplankton. A single equation for all lakes predicts the surface distribution of emergent biomass, relative to lake depth at any location, from vertical profiles of phytoplankton production. The mean size of dipteran adults was related to lake depth at the point of emergence and average phytoplankton production. An empirical model which used data on the vertical profile, and lake average, of phytoplankton production was developed to predict the number of Diptera emerging from each depth. The maximum depth of emergence was related to depth of the euphotic zone and average phytoplankton production in each lake. Initial tests suggested that the models may provide useful predictions of dipteran emergence for a wider spectrum of lakes.Key words: aquatic insects, Diptera, Chironomidae, eutrophication, primary production

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.

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