An analysis of mean growing season concentrations of chlorophyll, total phosphorus (TP), and total nitrogen (TN) in 228 north latitude lakes confirms previous observations that chlorophyll yield is dependent both on the phosphorus concentration and on the TN:TP ratio. Of two modified chlorophyll models which depend explicitly on both nitrogen and phosphorus developed and tested, one, a multiple regression model, appears to greatly reduce the error of chlorophyll prediction in lakes. A theoretical framework is presented which provides an explanation for the observed effects of N:P ratios.

https://aslopubs.onlinelibrary.wiley.com/doi/epdf/10.4319/lo.1982.27.6.1101

The nitrogen and phosphorus dependence of algal biomass in lakes: An empirical and theoretical analysis1

We examined stressors that have led to profound ecological changes in the Lake Ontario ecosystem and its fish community since 1970. The most notable changes have been reductions in phosphorus loading, invasion by Dreissena spp., fisheries management through stocking of exotic salmonids and control of sea lamprey (Petromyzon marinus), and fish harvest by anglers and double-crested cormorants (Phalacrocorax auritus). The response to these stressors has led to (i) declines in both algal photosynthesis and epilimnetic zooplankton production, ( ii) decreases in alewife (Alosa pseudoharengus) abundance, (iii) declines in native Diporeia and lake whitefish (Coregonus clupeaformis), (iv) behavioral shifts in alewife spatial distribution benefitting native lake trout ( Salvelinus namaycush), threespine stickleback (Gasterosteus aculeatus), and emerald shiner (Notropis atherinoides) populations, (v) dramatic increases in water clarity, (vi) predation impacts by cormorants on select fish species, and (vii) lake trout recruitment bottlenecks associated with alewife-induced thiamine deficiency. We expect stressor responses associated with anthropogenic forces like exotic species invasions and global climate warming to continue to impact the Lake Ontario ecosystem in the future and recommend continuous long-term ecological studies to enhance scientific understanding and management of this important resource.

/pdf/lake-ontario-food-web-dynamics-in-a-changing-ecosystem-1970-2uuwoh7fru.pdf

Lake Ontario: food web dynamics in a changing ecosystem (1970-2000)

SUMMARY. 1. Limiting nutrients for phytoplankton were studied experimentally in eight mountain lakes of central Colorado between May and November of 1984.



2. Five categories of phytoplankton limitation were identified: no limitation, N limitation, P limitation, concurrent limitation (stimulation only by simultaneous additions of N and P), and reciprocal limitation (stimulation by addition of either N or P). The phytoplankton communities of three lakes were primarily N-limited, one was primarily phosphorus-limited, and four showed primarily combined limitation (concurrent or reciprocal). Switching between categories of limitation was also observed within lakes. Nitrogen was the most frequently limiting nutrient; N, either alone or in combination with P, accounted for 79% of all observed instances of limitation.



3. Nine indices were tested for effectiveness in predicting phytoplankton limitation by N and P. The best indices for discriminating all limitations were ratios of dissolved inorganic N: total P (84% accuracy) and dissolved inorganic N:total dissolved P (80% accuracy). The effectiveness of these indices may be explained by the degree to which they represent N and P fractions actually available to the phytoplankton.

Phytoplankton nutrient limitation in Colorado mountain lakes

An analysis of growing season measurements of daily primary productivity, chlorophyll, water chemistry, and transparency from 58 north temperate lakes shows a strong correlation between volumetric rates of photosynthesis, chlorophyll, and nutrients. Mean daily rates of photosynthesis per unit volume euphotic zone, v, are correlated with mean chlorophyll concentration (r2 = 0.80). The mean daily rate of photosynthesis at optimal depth, Āopt, is highly correlated with mean total P(r2 = 0.95), and with mean total N(r2 = 0.91). In contrast, integral rates of photosynthesis are linked less tightly to nutrient concentration because of their simultaneous dependence on transparency. The Dillon-Rigler phosphorus loading model is extended to predict volumetric rates of photosynthesis (v and Āopt) in lakes where the N:P balance indicates control by phosphorus (N:P ⩾ 13).

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1979.24.6.1051

Nutrient dependence of primary productivity in lakes1

A critical review of batch-culture freshwater algal toxicity test methods (algal growth inhibition tests) is presented. Interlaboratory comparisons have revealed that the results from such tests can vary a great deal, in some cases by more than three orders of magnitude. The potential causes of variability are the physical/chemical experimental parameters. Algal tests, however, need not be very strictly standardized in order to be reproducible if tests are appropriately conducted and the experimental parameters are understood and controlled. Many algal toxicity data reported in the literature seem to have been generated from tests performed with an excessively high biomass and under poor gas-exchange conditions, the combination of which will cause an insufficient supply of carbon dioxide leading to high pH levels and sometimes even to mass-transport (carbon dioxide)-limited linear growth. Poor gas-exchange conditions will prevail unless the test flasks are shaken or aerated continuously. Literature data on the toxicity of chemicals to algae should therefore be used only with careful evaluation of the test method involved.

https://setac.onlinelibrary.wiley.com/doi/pdf/10.1002/etc.5620080807

Methods for growth inhibition toxicity tests with freshwater algae

(1978). Water chemical analyses and/or algal assay? — Sewage effluent and polluted lake water studies. SIL Communications, 1953-1996: Vol. 21, No. 1, pp. 352-363.

Water chemical analyses and/or algal assay? — Sewage effluent and polluted lake water studies: With 2 figures and 2 tables in the text

Recovery of polluted lakes. a swedish research program on the effects of advanced waste water treatment and sewage diversion

Two algal assay methods (batch), one with Selenastrum capricornutum and one with this species together with Ankistrodesmus falcatus, Chlorella homosphaera, Euglena gracilis, and Scenedesmus quadric...

Algal assay procedure with one or five species. Minitest: With 6 figures and 2 tables in the text

SUMMARY Water chemistry and algal assays in surface water (0-2 m) are presented from five eutrophic lakes, all recipients for sewage effluent The lakes were studied intensively during the period May-October 1973 Some common features in water chemical aspects were: a decline in inorganic-N during summer, PO4 always in excess, and a high chlorophyll a content throughout the period The more productive lakes, however, exhibited a high N supply even during intensive algal growth The total-N: total-P quotient was very low for most of the test period giving N limited algal growth with the alga Selenastrum capricornutum A N:P quotient of 15:1 in the lake water seemed to be a critical value concerning N- or P-limitation for this test alga The sum of lake and of algal assay chlorophyll was used to indicate the algal growth potential (AGP) in lakes, and is proposed as a simple type of “trophic index” The lakes presented have been chosen to illustrate the variability amongst lakes where N is the most limiting nutrient In the less productive ones N probably influenced the production level to a larger extent than in the more eutrophic ones, where other factors such as light or zooplankton predation mainly limited phytoplankton growth

Anders Claesson

Papers

Water chemical analyses and/or algal assay? — Sewage effluent and polluted lake water studies: With 2 figures and 2 tables in the text

Recovery of polluted lakes. a swedish research program on the effects of advanced waste water treatment and sewage diversion

Algal assay procedure with one or five species. Minitest: With 6 figures and 2 tables in the text

Nitrogen—a growth limiting nutrient in eutrophic lakes

Algal assays with wastewater to determine the availability of phosphorus for algal growth: With 3 figures and 1 table in the text