Trophic Level Relationships in Pelagic Food Webs: Comparisons Derived from Long-Term Data Sets for Oneida Lake, New York (USA), and Lake St. George, Ontario (Canada)

McQueen, Donald J.; Mills, Edward L.; Forney, John L.; Johannes, Mark R. S.

doi:10.1139/f92-177

Cited by 28 publications

(10 citation statements)

References 25 publications

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“…Given its proximity to these sources, the Wangjia Zhai (HP) site was expected to have higher concentrations of contaminant in the water and biota. As observed in most lake studies, we found that nutrient enrichment resulted in high algal densities at this site [McQueen et al, 1992;Carpenter et al, 1998;Smith et al, 1999]. However, the dissolved concentrations of Hg and As were lowest there and highest in the most remote site, Quan Tou.…”

Section: Discussionsupporting

confidence: 75%

Mercury and Arsenic Bioaccumulation and Eutrophication in Baiyangdian Lake, China

Chen

Pickhardt

et al. 2007

Water Air Soil Pollut

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Hg and As are widespread contaminants globally and particularly in Asia. We conducted a field study in Baiyangdian Lake, the largest lake in the North China Plain, to investigate bioaccumulation and trophic transfer of potentially toxic metals (total mercury and arsenic) in sites differing in proximity from the major point sources of nutrients and metals. Hg concentrations in fish and As concentrations in water are above critical threshold levels (US Environmental Protection Agency based) considered to pose some risk to humans and wildlife. Hg concentrations in biota are within the range of concentrations in lakes in the Northeast US despite the high levels of Hg emission and deposition in China whereas As concentrations are much higher. Dissolved concentrations of both Hg and As decrease with increasing chlorophyll concentrations suggesting that there is significant uptake of metal from water by algae. These results provide evidence for algal blooms controlling dissolved metal concentrations and potentially mitigating the trophic transfer of Hg to fish. This study also underscores the need for further investigation into this contaminated ecosystem and others like it in China that are an important source of fish and drinking water for consumption by local human populations.

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Section: Discussionsupporting

confidence: 75%

Mercury and Arsenic Bioaccumulation and Eutrophication in Baiyangdian Lake, China

Chen

Pickhardt

et al. 2007

Water Air Soil Pollut

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“…The availability of resources and consumption by predators have been considered key controls of the dynamics of bacterial communities. Regulation by resources and/or predators are often referred to as bottom-up and top-down control [25,26], but these concepts require some clarification when applied to bacteria. Limiting resources for bacteria are, typically, labile carbon substrates as well inorganic and organic N and P. If resource regulation is important, increases in the loading of nutrients or increases in labile carbon from, for example, phytoplankton blooms should increase bacterial biomass and productivity.…”

Section: Introductionmentioning

confidence: 99%

Comparative and experimental approaches to top-down and bottom-up regulation of bacteria

1994

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The regulation of bacterial community biomass and productivity by resources and predators is a central concern in the study of microbial food webs. Resource or bottom-up regulation refers to the limitation of bacteria by carbon and nutrients derived from allocthonous inputs, primary production, and heterotrophic production. Predatory or top-down regulation refers to the limitation of bacteria below levels supportable by resources alone. Large scale comparative studies demonstrate strong correlations between bacterial productivity and biomass, suggesting significant resource regulation. Comparisons of the abundances of heterotrophic flagellates and bacteria, however, imply that in some cases there may be top-down regulation of bacteria in eutrophic environments. Experimental studies in lakes support the importance of resource regulation and reveal little top-down control from protozoans. Increases in bacterial abundance and production with nutrient enrichment were limited in enclosure experiments with high abundances of the cladoceran, Daphnia. Regulation of bacteria by Daphnia may occur in many lakes seasonally and prevail in some lakes throughout the year where these animals sustain dense populations. In most situations, however, bacteria appear to be limited primarily by resources.

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“…But bacteria are also significant consumers of phosphorus in pelagic systems (Rothhaupt, 1992) . Nutrient excretion, particularly P, by fish has also attracted attention recently (Braband et al, 25 1990 ;Kraft, 1992 ;McQueen et al, 1992 ;Schindler etal., 1993) .…”

Section: Introductionmentioning

confidence: 99%

Zooplankton as a compound mineralising and synthesizing system: phosphorus excretion

1995

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Data on phosphate excretion rates of zooplankton are based on measurements using the pelagic crustacean zooplankton of Lake Vechten and laboratory-cultured Daphnia galeata . In case of Daphnia sp we measured the effects of feeding on P-rich algae and P-poor algae (Scenedesmus) as food on the P-excretion rates at 20 °C . The excretion rates of the natural zooplankton community, irrespective of the influence of the factors mentioned, varied by an order of magnitude : 0 .025-0 .275,49 P04-P mg -1 C in zooplankton (C 2p) h -1 . The temperature accounted for about half the observed variation in excretion rates . The mean excretion rates in the lake, computed for 20 °C, varied between 0 .141 and 0 .260 pg P mg-1 C,,, h -1 . Based on data of zooplankton biomass in the lake the P-regeneration rates by zooplankton covered between 22 and 239% of the P-demand of phytoplankton during the different months of the study period.In D. galeata, whereas the C/P ratios of the Scenedesmus used as food differed by a factor 5 in the experiments, the excretion rates differed by factor 3 only . Despite the higher P-excretion rates (0 .258 ± 0 .022 pg P04-P Mg-' C h -1 ) of the daphnids fed with P-rich food than those fed with P-poor food (0 .105 ± 0.047 pg P04-P Mg-' C h -1 ), both the categories of the animals were apparently conserving P . A survey of the literature on zooplankton excretion shows that in Daphnia the excretion rates vary by a factor 30, irrespective of the species and size of animals and method of estimation and temperature used .About two-thirds of this variation can be explained by size and temperature . A major problem of comparability of studies on P-regeneration by zooplankton relates to the existing techniques of P determination, which necessitates concentrating the animals several times above the in situ concentration (crowding) and prolonged experimental duration (starving), both of which manifest in marked changes that probably lead to underestimation of the `real' rates .

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Trophic Level Relationships in Pelagic Food Webs: Comparisons Derived from Long-Term Data Sets for Oneida Lake, New York (USA), and Lake St. George, Ontario (Canada)

Cited by 28 publications

References 25 publications

Mercury and Arsenic Bioaccumulation and Eutrophication in Baiyangdian Lake, China

Mercury and Arsenic Bioaccumulation and Eutrophication in Baiyangdian Lake, China

Comparative and experimental approaches to top-down and bottom-up regulation of bacteria

Zooplankton as a compound mineralising and synthesizing system: phosphorus excretion

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