Long-term trends in zooplankton of Dorset, Ontario, lakes: the probable interactive effects of changes in pH, total phosphorus, dissolved organic carbon, and predators

2008 ◽  
Vol 65 (5) ◽  
pp. 862-877 ◽  
Author(s):  
Norman D Yan ◽  
Keith M Somers ◽  
Robert E Girard ◽  
Andrew M Paterson ◽  
W. (Bill) Keller ◽  
...  

Time trends in abundance, body size, species richness, and species composition indicate that crustacean zooplankton communities of southern Canadian Shield lakes changed between 1980 and 2003. Total abundance did not decline despite reductions in total phosphorus, but all other metrics changed. Species richness declined in Harp Lake (Ontario, Canada) following its Bythotrephes invasion, but richness increased in three other lakes. Average cladoceran body length increased from 0.6 to 1.0 mm in seven of the lakes, as larger-bodied taxa replaced smaller ones. Correlations with water quality and fish metrics suggest that cladoceran size increases were attributable to many factors: a decline in food availability following declining phosphorus levels increasing the competitive advantage of larger herbivores, a decline in acidity favouring the larger, acid-sensitive daphniids, and reduced risk of planktivory linked to a rise in dissolved organic carbon levels and changes in predation regimes. Zooplankton communities on the Canadian Shield are changing, and these changes are best viewed in a multiple-stressor context. Key anthropogenic stressors have also changed and may do so again if Ca concentrations continue to decline.

2015 ◽  
Vol 23 (4) ◽  
pp. 395-413 ◽  
Author(s):  
Shakira S.E. Azan ◽  
Shelley E. Arnott ◽  
Norman D. Yan

Anthropogenic stressors including acid deposition, invasive species, and calcium (Ca) decline have produced widespread damage to Canadian Shield lakes, especially to their zooplankton communities. Here, we review current knowledge on the individual effects on zooplankton by the non-indigenous predator Bythotrephes longimanus and Ca decline; we identify knowledge gaps in this literature and examine the likely interactive impacts of Bythotrephes invasions and Ca decline on zooplankton. The negative impacts of Bythotrephes longimanus on zooplankton communities are well known, whereas current understanding of the effects of declining Ca on zooplankton is restricted to Daphnia spp.; hence, there is a large knowledge gap on how declining Ca may affect zooplankton communities in general. The co-occurring impacts of Bythotrephes and declining Ca have rarely been studied at the species level, and we expect daphniids, particularly Daphnia retrocurva and Daphnia pulicaria, to be the most sensitive to both stressors. We also expect a synergistic negative interaction on cladocerans in lakes with both stressors, leaving a community dominated by Holopedium glacialis and (or) copepods. Our predictions form testable hypotheses but since species and ecosystem response to multiple stressors are difficult to predict, we may actually see ecological surprises in Canadian Shield lakes as Bythotrephes continues to spread and Ca levels continue to fall.


1997 ◽  
Vol 54 (10) ◽  
pp. 2215-2227 ◽  
Author(s):  
Pierre D'Arcy ◽  
Richard Carignan

For 30 Canadian Shield lakes of southeastern Quebec, catchment slope and lake morphometry account for 50-70% of the variability of chlorophyll a (Chl a), dissolved organic carbon (DOC), total phosphorus (TP), NO3- , and NH4+ . Dissolved organic carbon, TP, Chl a, Ca, and Mg are negatively related to catchment slope, whereas NO3- and NH4+ increase with increasing slope. Concentrations of more conservative constituents (SO42-, Na, K) increase with decreasing elevation as a result of higher evapotranspiration and lower precipitation at low elevations. Catchment variables (slope, drainage area, percent wetlands) are as good predictors of Chl a (r2 = 0.7) as are water chemistry variables (TP, Ca, Mg, and pH). Dominant vegetation (deciduous vs. coniferous) has little or no influence on lake water chemistry. Hydrogeological data for the Canadian Shield suggest that, during periods of high runoff, the development of waterlogged areas and the importance of overland flow on saturated soils are inversely proportional to catchment slope. We propose that the strong influence of catchment slope on water quality is due to slope-dependent seasonal waterlogging, which determines the fate (retention or export to surface waters) of dissolved substances produced within and moving through the forest floor.


1994 ◽  
Vol 51 (11) ◽  
pp. 2424-2434 ◽  
Author(s):  
W. Keller ◽  
M. Conlon

To investigate relationships between crustacean zooplankton communities and lake morphometry we sampled 60 near-neutral Precambrian Shield lakes, including many small, shallow lakes. Morphometry-related patterns in the distributions of many zooplankton species were evident. Lake depth determined the occurrence of hypolimnetic species, and lake depth, lake area, and watershed area were positively related to the species richness of zooplankton communities. Among lakes with fish, deeper (maximum depth >8 m) lakes were characterized by greater species richness, higher abundances of a number of species including Daphnia pulex, Daphnia galeata mendotae, Daphnia dubia, and Diacyclops bicuspidatus thomasi, and lower abundances of Leptodiaptomus minutus, than shallower (maximum depth <8 m) lakes. Increased predation pressure by small fish species in smaller, shallower lakes probably influenced the observed species distributions. Lakes inferred to be fishless based on the presence of Chaoborus americanus typically had relatively high abundances of D. pulex, Diaphanosoma brachyurum, and Aglaodiaptomus leptopus, and absences of D. g. mendotae and D. birgei, patterns attributable to intense invertebrate predation on zooplankton.


2001 ◽  
Vol 58 (3) ◽  
pp. 543-550 ◽  
Author(s):  
Sushil S Dixit ◽  
W (Bill) Keller ◽  
Aruna S Dixit ◽  
John P Smol

Paleolimnological approaches have provided strong inference models for lake-water acidity and metal concentrations in Sudbury-area lakes, but calibration data have not yet been explored for inferring lake-water dissolved organic carbon (DOC). A review of available limnological data provided DOC values for 80 of our 105 calibration lakes, allowing us to examine the relative importance of DOC in determining the distribution of diatom assemblages in Canadian Shield lakes, such as those in the Sudbury region. Canonical correspondence analysis (CCA) indicated that lake-water DOC explained a significant proportion of variation in the diatom data. Our weighted-averaging DOC model showed a strong relationship (r2 = 0.63) between measured and inferred DOC. Using this model, we reconstructed historical DOC concentrations in three Sudbury-area lakes, and then estimated temporal changes in UV-B penetration. These reconstructions showed that lake water DOC concentrations and underwater UV-B penetration have changed markedly in two of the three lakes modeled. The close correspondence between inferred and measured DOC for the 1980s in all three lakes provides further evidence that we have accurately inferred DOC concentrations. Quantitative DOC reconstructions in Sudbury-area lakes offer an excellent technique for assessing past changes in DOC concentrations and UV-B penetration in Canadian Shield lakes.


2003 ◽  
Vol 60 (11) ◽  
pp. 1307-1313 ◽  
Author(s):  
Stephanie A Boudreau ◽  
Norman D Yan

The nonindigenous predatory cladoceran Bythotrephes longimanus is spreading rapidly among Canadian Shield lakes, but only one case study of its impacts exists. In Harp Lake, the abundances of several cladoceran and one cyclopoid species fell after the invasion, and far fewer species benefited. To determine if Harp Lake provides typical results, we compared the summer crustacean zooplankton communities of 17 invaded and 13 noninvaded (reference) lakes in Ontario. The communities of the two lake groups differed. Average species richness was 30% higher in the reference (15.3 species) vs. the invaded lakes (11.8 species). Total zooplankton biomass was significantly lower in the invaded lakes, mainly because of lower abundances of all common epilimnetic cladoceran species. As these results were quite similar to those of Harp Lake, it is apparent that current summer zooplankton communities of Canadian Shield lakes with Bythotrephes differ substantially from noninvaded lakes.


2007 ◽  
Vol 64 (2) ◽  
pp. 181-186 ◽  
Author(s):  
Andrea Bertolo ◽  
Pierre Magnan

There is increasing interest in the effects of allochthonous carbon on lake food webs. By temporarily increasing levels of dissolved organic carbon (DOC) in lakes, logging can help us understand how carbon from the watershed could affect lake biota. The goals of this study were to determine whether (i) logging has a significant effect on the abundance of young-of-the-year (YOY) yellow perch (Perca flavescens) in Canadian Shield lakes and (ii) any changes in yellow perch recruitment could be related to increases in nutrients (N and P) and (or) DOC following logging. To do this, we examined 22 Canadian Shield lakes: the watersheds of 13 were not impacted, while 9 underwent logging (1%–78% of the watershed area). We found that the relative abundance of YOY yellow perch increased after logging in proportion to the ratio between the area of the logged watershed and the lake volume. We show that this effect is likely explained by an increase in DOC following logging. This might be related to (i) an increase in secondary productivity due to a positive effect of terrestrial carbon on the microbial loop and (or) (ii) an increased hatching success and (or) larval survival due to a greater protection from UV radiation by DOC.


1990 ◽  
Vol 24 (9) ◽  
pp. 1367-1372 ◽  
Author(s):  
Norman D. Yan ◽  
Gerald L. Mackie ◽  
Peter J. Dillon

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