The Lake Ontario Life Support System

1987 ◽  
Vol 44 (12) ◽  
pp. 2230-2240 ◽  
Author(s):  
D. R. S. Lean ◽  
H-J. Fricker ◽  
M. N. Charlton ◽  
R. L. Cuhel ◽  
F. R. Pick
Keyword(s):  
Primary Productivity ◽  
Life Support ◽  
Lake Ontario ◽  
Trophic Levels ◽  
Phosphorus Concentration ◽  
Nutrient Regeneration ◽  
Particulate Carbon ◽  
Calcium Carbonate Precipitation ◽  
Mixing Processes ◽  
Aquatic Food

Primary productivity provides most of the energy to support aquatic food chains. The rate is not only influenced by available solar radiation but also by temperature, availability of phosphorus, and the influence of physical mixing processes. The special features of Lake Ontario such as changes in phosphorus concentration, calcium carbonate precipitation, and silica deficiency on primary productivity, concentration of particulate carbon, and chlorophyll are discussed. Our lack of understanding of food chain and nutrient regeneration processes is illustrated through our failure to balance carbon production with losses through zooplankton grazing and sedimentation. It was demonstrated, however, that bacteria are not responsible for nutrient regeneration through "mineralization" but nutrients are effectively recycled in the water column at the second and third trophic levels.

Biogeochemical influences on the carbon isotope signatures of Lake Ontario biota

1999 ◽  
Vol 56 (11) ◽  
pp. 2211-2218 ◽  
Author(s):  
M F Leggett ◽  
M R Servos ◽  
R Hesslein ◽  
O Johannsson ◽  
E S Millard ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Primary Productivity ◽  
Benthic Invertebrates ◽  
Food Source ◽  
Spring Bloom ◽  
Lake Ontario ◽  
Trophic Levels ◽  
Sediment Surface ◽  
Food Web Interactions ◽  
Primary Consumers

Particulate organic matter (POM), zooplankton, and benthic invertebrates were sampled seasonally at a midlake and east basin site in Lake Ontario. The δ13C values of POM samples were compared with measurements of chlorophyll a concentrations, areal rates of primary productivity, concentrations of dissolved free CO2 (CO2(aq)), and the δ13C of zooplankton and benthic invertebrates. The δ13C of POM was significantly correlated with the concentration of CO2(aq) at the east basin site. No correlation was found between chlorophyll a concentrations, areal rates of primary productivity, and the δ13C of POM. The δ13C of zooplankton was not always similar to the δ13C of the POM fraction collected, indicative of the complexity of food web interactions within the lower trophic levels. The δ13C of benthic invertebrates feeding on the sediment surface was similar to that of POM produced prior to stratification, indicating the importance of the spring bloom as a food source for benthic primary consumers.

scholarly journals Elevated temperature and browning increase dietary methylmercury, but decrease essential fatty acids at the base of lake food webs

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pianpian Wu ◽  
Martin J. Kainz ◽  
Fernando Valdés ◽  
Siwen Zheng ◽  
Katharina Winter ◽  
...  
Keyword(s):  
Climate Change ◽  
Fatty Acids ◽  
Organic Matter ◽  
Food Webs ◽  
Essential Fatty Acids ◽  
Trophic Levels ◽  
Climate Change Scenarios ◽  
Essential Nutrients ◽  
Aquatic Food Webs ◽  
Aquatic Food

AbstractClimate change scenarios predict increases in temperature and organic matter supply from land to water, which affect trophic transfer of nutrients and contaminants in aquatic food webs. How essential nutrients, such as polyunsaturated fatty acids (PUFA), and potentially toxic contaminants, such as methylmercury (MeHg), at the base of aquatic food webs will be affected under climate change scenarios, remains unclear. The objective of this outdoor mesocosm study was to examine how increased water temperature and terrestrially-derived dissolved organic matter supply (tDOM; i.e., lake browning), and the interaction of both, will influence MeHg and PUFA in organisms at the base of food webs (i.e. seston; the most edible plankton size for zooplankton) in subalpine lake ecosystems. The interaction of higher temperature and tDOM increased the burden of MeHg in seston (< 40 μm) and larger sized plankton (microplankton; 40–200 μm), while the MeHg content per unit biomass remained stable. However, PUFA decreased in seston, but increased in microplankton, consisting mainly of filamentous algae, which are less readily bioavailable to zooplankton. We revealed elevated dietary exposure to MeHg, yet decreased supply of dietary PUFA to aquatic consumers with increasing temperature and tDOM supply. This experimental study provides evidence that the overall food quality at the base of aquatic food webs deteriorates during ongoing climate change scenarios by increasing the supply of toxic MeHg and lowering the dietary access to essential nutrients of consumers at higher trophic levels.

scholarly journals Aquatic food web research in mesocosms: a literature survey

2020 ◽  
Author(s):  
Csenge Póda ◽  
Ferenc Jordán
Keyword(s):  
Food Web ◽  
Multiple Stressors ◽  
Experimental Testing ◽  
Literature Survey ◽  
Trophic Levels ◽  
Combined Effects ◽  
Theoretical Concepts ◽  
Aquatic Food ◽  
Emerging Topics ◽  
Web Research

Food web research feeds ecology with elementary theoretical concepts that need controlled experimental testing. Mesocosm facilities offer multiple ways to execute experimental food web research in a rigorous way. We performed a literature survey to overview food web research implementing the mesocosm approach. Our goal was to summarise quantitatively how the mesocosm approach has formerly been used and question how to best utilise mesocosms for the emerging topics in food web research in the future. We suggest increasing the number of replicates, extending the duration of the experiments, involving higher trophic levels and addressing the combined effects of multiple stressors.

scholarly journals Patterns, dynamics and consequences of microplastic ingestion by the temperate coral, Astrangia poculata

2019 ◽  
Vol 286 (1905) ◽  
pp. 20190726 ◽  
Author(s):  
Randi D. Rotjan ◽  
Koty H. Sharp ◽  
Anna E. Gauthier ◽  
Rowan Yelton ◽  
Eliya M. Baron Lopez ◽  
...  
Keyword(s):  
Rhode Island ◽  
Marine Invertebrates ◽  
Trophic Levels ◽  
Coastal Environments ◽  
Monitoring Tool ◽  
Astrangia Poculata ◽  
Temperate Coral ◽  
Inhibit Food Intake ◽  
Aquatic Food ◽  
Behavioural Dynamics

Microplastics (less than 5 mm) are a recognized threat to aquatic food webs because they are ingested at multiple trophic levels and may bioaccumulate. In urban coastal environments, high densities of microplastics may disrupt nutritional intake. However, behavioural dynamics and consequences of microparticle ingestion are still poorly understood. As filter or suspension feeders, benthic marine invertebrates are vulnerable to microplastic ingestion. We explored microplastic ingestion by the temperate coral Astrangia poculata . We detected an average of over 100 microplastic particles per polyp in wild-captured colonies from Rhode Island. In the laboratory, corals were fed microbeads to characterize ingestion preference and retention of microplastics and consequences on feeding behaviour. Corals were fed biofilmed microplastics to test whether plastics serve as vectors for microbes. Ingested microplastics were apparent within the mesenterial tissues of the gastrovascular cavity. Corals preferred microplastic beads and declined subsequent offerings of brine shrimp eggs of the same diameter, suggesting that microplastic ingestion can inhibit food intake. The corals co-ingested Escherichia coli cells with microbeads. These findings detail specific mechanisms by which microplastics threaten corals, but also hint that the coral A. poculata , which has a large coastal range, may serve as a useful bioindicator and monitoring tool for microplastic pollution.

scholarly journals Selenium Interactions with Algae: Chemical Processes at Biological Uptake Sites, Bioaccumulation, and Intracellular Metabolism

Plants ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 528 ◽  
Author(s):  
Dominic E. Ponton ◽  
Stephanie D. Graves ◽  
Claude Fortin ◽  
David Janz ◽  
Marc Amyot ◽  
...  
Keyword(s):  
Food Webs ◽  
Mechanistic Model ◽  
Trophic Levels ◽  
Primary Producers ◽  
Organic Selenium ◽  
Selenium Uptake ◽  
Aquatic Food Webs ◽  
Uptake Sites ◽  
Aquatic Food ◽  
Lentic Systems

Selenium (Se) uptake by primary producers is the most variable and important step in determining Se concentrations at higher trophic levels in aquatic food webs. We gathered data available about the Se bioaccumulation at the base of aquatic food webs and analyzed its relationship with Se concentrations in water. This important dataset was separated into lotic and lentic systems to provide a reliable model to estimate Se in primary producers from aqueous exposure. We observed that lentic systems had higher organic selenium and selenite concentrations than in lotic systems and selenate concentrations were higher in lotic environments. Selenium uptake by algae is mostly driven by Se concentrations, speciation and competition with other anions, and is as well influenced by pH. Based on Se species uptake by algae in the laboratory, we proposed an accurate mechanistic model of competition between sulfate and inorganic Se species at algal uptake sites. Intracellular Se transformations and incorporation into selenoproteins as well as the mechanisms through which Se can induce toxicity in algae has also been reviewed. We provided a new tool for risk assessment strategies to better predict accumulation in primary consumers and consequently to higher trophic levels, and we identified some research needs that could fill knowledge gaps.

Phosphorus Flux through Epilimnetic Zooplankton from Lake Ontario: Relationship with Body Size and Significance to Phytoplankton

1984 ◽  
Vol 41 (11) ◽  
pp. 1702-1712 ◽  
Author(s):  
W. D. Taylor
Keyword(s):  
Body Size ◽  
Phosphorus Uptake ◽  
Lake Ontario ◽  
Trophic Levels ◽  
Phytoplankton Production ◽  
Unit Size ◽  
Release Rates ◽  
Zooplankton Size ◽  
Uptake Rates ◽  
Phosphorus Flux

The flux of phosphate through epilimnetic zooplankton from Lake Ontario was measured by adding 32PO4 into whole lakewater, monitoring its accumulation by zooplankton over 48 h, and then measuring its release when animals were returned to unlabelled lake water. Phosphorus uptake was calculated as the sum of accumulation and release rates. The 10 species examined ranged in size from 36-μm Codonella cratera to 1-mm Daphnia retrocurva. Phosphorus uptake rates of herbivorous zooplankton ranged about 200-fold and increased with body size both within and among species, although not proportionally. Among species, there was a pronounced allometry, with smaller species having much higher rates per unit size. This allometry is similar to that described for other metabolic parameters and body size. There was no tendency for smaller species to release a greater fraction of the label they took up. These results suggest that the biomass of zooplankton consuming a given phytoplankton production will be much smaller if small zooplankton dominate, and therefore, this phosphorus sink will be much smaller. Further, the flow of phosphorus to higher trophic levels may be reduced. The result of changing the zooplankton size-distribution may be to change the amount of spring total phosphorus available to summer phytoplankton.

The English–Wabigoon River System: V. Mercury and Selenium Bioaccumulation as a Function of Aquatic Primary Productivity

1983 ◽  
Vol 40 (12) ◽  
pp. 2251-2259 ◽  
Author(s):  
John W. M. Rudd ◽  
Michael A. Turner
Keyword(s):  
Growth Rate ◽  
Primary Productivity ◽  
Growth Rates ◽  
River System ◽  
Whole Body ◽  
Aquatic Food Chain ◽  
Mercury Bioaccumulation ◽  
Aquatic Food ◽  
Stimulation Of

An experiment was carried out in four 100-m3 in situ enclosures to determine the effect of primary production rate on mercury and selenium concentrations of biota and to test the possibility of ameliorating mercury pollution problems by increasing ecosystem primary productivity. Two enclosures were controls. Primary productivity in a third enclosure was increased fourfold by addition of NaNO3 and NaH2PO4. This stimulation was not sufficient to change pH although the growth rate of fish was enhanced. In this enclosure, mercury concentrations in pearl dace (Semotilus margarita) whole body and muscle samples increased two- and five-fold, respectively, exceeding the dilution of mercury by the enhanced growth rates. In the fourth enclosure, at the highest rate of nutrient addition, primary productivity was increased ninefold, pH was elevated from about 7.9 to 9.2, and the growth rate of fish was stimulated. In this case, the elevation of pH retarded the rate of mercury bioaccumulation in comparison with the enclosure of intermediate productivity. Based on these results, stimulation of primary productivity is not recommended as a mercury ameliorating procedure. Stimulation of primary productivity resulted in a general decrease in the concentration of selenium in the aquatic food chain probably resulting from dilution of selenium by enhanced growth rates of fish and other biota.

Temporal trends of polychlorinated biphenyls (PCBs) in Lake Ontario fish and invertebrates

1999 ◽  
Vol 7 (4) ◽  
pp. 203-223 ◽  
Author(s):  
E Bentzen ◽  
D Mackay ◽  
B E Hickie ◽  
D RS Lean
Keyword(s):  
Food Web ◽  
Lake Trout ◽  
Temporal Trends ◽  
Lake Ontario ◽  
Fish Food ◽  
International Joint Commission ◽  
Analytical Protocol ◽  
Fish Lipid ◽  
Key Species ◽  
Aquatic Food

A comprehensive review is presented of changes of PCB concentrations in aquatic biota collected from Lake Ontario between 1977 and 1993, with emphasis on data for lake trout. Results of three major lake trout surveys from Canadian and United States agencies indicate lake trout PCBs have declined from the early 1980s, but changes in recent years are masked by interannual variability. These results also apply to other biota in the aquatic food web. PCB concentrations were consistent among the surveys after consideration of fish lipid content, age or size and analytical protocol. Variability of 20 to 30% in annual average estimates is attributed to both analytical and in situ sources. Current levels of PCBs in many salmonids exceed PCB consumption and wildlife protection advisories. The average half-life for PCBs in Lake Ontario biota is about 12 years and it will take three to four times that to reach the International Joint Commission target of 100 ng/g (ww) for protection of wildlife. It is essential that the design of monitoring programs ensures consistent, coordinated sampling and analysis. A monitoring strategy of annual sampling of key species supplemented with periodic intensive sampling of the entire food web (e.g., every 5 years) is suggested as more effective than current practices. There is a frequently neglected need for fuller interpretation of contaminant dynamics based on complementary research on the nature of the changing biotic and abiotic environments in a complex aquatic ecosystem like Lake Ontario. Key words: Lake Ontario, PCBs, fish, food webs, monitoring data, bioaccumulation.

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