Spring isothermal mixing in the Great Lakes: evidence of nutrient limitation and nutrient-light interactions in a suboptimal light environment

2000 ◽  
Vol 57 (9) ◽  
pp. 1901-1910 ◽  
Author(s):  
G L Fahnenstiel ◽  
R A Stone ◽  
M J McCormick ◽  
C L Schelske ◽  
S E Lohrenz
Keyword(s):  
Great Lakes ◽  
Growth Rates ◽  
Nutrient Enrichment ◽  
Light Availability ◽  
Light Limitation ◽  
Phytoplankton Communities ◽  
Growth Irradiance ◽  
Enrichment Experiments ◽  
Isothermal Mixing

During the spring isothermal mixing period (April-May) in 1993-1995, photosynthesis-irradiance and growth-irradiance experiments were conducted in Lakes Erie, Huron, Michigan, and Ontario to assess light limitation. Additionally, nutrient enrichment experiments were conducted in Lake Ontario. Results from the photosynthesis-irradiance experiments suggested that phytoplankton communities in all the lakes can be either light limited or light saturated, as the threshold parameter (Ik) was similar to mean water column irradiances (mean Iwc, ratio = 1.0). Growth-irradiance experiments also suggested the potential for light saturation; mean daily irradiance exceeded the threshold growth irradiance (Ik,g) in 95% of cases. Growth rates became light saturated at lower irradiances than photosynthetic rates. Evidence for a nutrient-light interaction in controlling in situ growth rates was also found in the nutrient enrichment experiments at incubation irradiances [Formula: see text] mean Iwc. Our results suggest that an interaction between nutrients and light is often controlling phytoplankton growth during spring mixing in the Great Lakes. The role of these nutrient-light interactions has increased in the past decade due to increased light availability in the lower lakes caused by phosphorus load reductions and the filtering activities of nonindigenous mussels.

Nutrient Enrichment Experiments in Tropical Great Lakes Malawi/Nyasa and Victoria

2003 ◽  
Vol 29 ◽  
pp. 89-106 ◽  
Author(s):  
Stephanie J. Guildford ◽  
Robert E. Hecky ◽  
William D. Taylor ◽  
Rose Mugidde ◽  
Harvey A. Bootsma
Keyword(s):  
Great Lakes ◽  
Nutrient Enrichment ◽  
Enrichment Experiments

Silicon Contamination in Diatom Nutrient Enrichment Experiments

1983 ◽  
Vol 40 (5) ◽  
pp. 657-664 ◽  
Author(s):  
Stephen J. Tarapchak ◽  
David R. Slavens ◽  
Michael A. Quigley ◽  
Judith S. Tarapchak
Keyword(s):  
Growth Rates ◽  
Nutrient Enrichment ◽  
Lake Michigan ◽  
Pyrex Glass ◽  
Short Term ◽  
Photosynthetic Rates ◽  
Nutrient Bioassay ◽  
Enrichment Experiments ◽  
Silicon Contamination

Large amounts of biologically available silicon (Si) were released into solution from the walls of Pyrex glass reagent bottles and Erlenmeyer flasks during nutrient bioassay experiments using Lake Michigan water. Photosynthetic rates in short-term (4–7 h) incubations and diatom growth rates and maximum yields in long-term incubations (~7 d) were affected by these extraneous Si supplies. The results of conventional nutrient enrichment bioassays performed in low-Si environments can be seriously biased unless Si contamination from glass incubation containers is avoided.

Periphyton response to long-term nutrient enrichment in a shaded headwater stream

2005 ◽  
Vol 62 (9) ◽  
pp. 2033-2045 ◽  
Author(s):  
Jennifer L Greenwood ◽  
Amy D Rosemond
Keyword(s):  
Growth Rates ◽  
Nutrient Enrichment ◽  
Algal Species ◽  
Light Availability ◽  
Algal Growth ◽  
Detectable Effect ◽  
Long Term Effects ◽  
Tree Canopies ◽  
Periphyton Biomass

We maintained elevated but moderate concentrations of nitrogen and phosphorus continuously for 2 years in a heavily shaded headwater stream and compared effects on stream periphyton with a reference stream. Both streams were sampled for 1 year before treatment. Some measures of periphyton biomass (ash-free dry mass and chlorophyll a) responded positively to enrichment. Increased chlorophyll a was likely a result of higher chlorophyll per cell, as total algal biovolume did not change with enrichment. These differences were greatest during high-light months (November-May), when cellular growth rates (a proxy for production) were also highest with enrichment. Algal assemblages were dominated by diatoms and remained similar between the treatment and reference streams throughout the enrichment period. Although nutrients stimulated algal growth rates, the long-term effects of nutrient addition on periphyton biomass were small in magnitude compared with other published values and were potentially suppressed by light availability and invertebrate consumption. These and other factors may have also been important in limiting the algal species pool and thus a taxonomic response to enrichment. Our results indicate that in headwater streams with intact tree canopies, chronic nutrient enrichment at moderate concentrations may have little detectable effect on benthic algal composition or periphyton biomass. Although nutrients stimulated algal growth rates, the long-term effects of nutrient addition on periphyton biomass were small in magnitude compared with other published values and were potentially suppressed by light availability and invertebrate consumption. These and other factors may have also been important in limiting the algal species pool and thus a taxonomic response to enrichment. Our results indicate that in headwater streams with intact tree canopies, chronic nutrient enrichment at moderate concentrations may have little detectable effect on benthic algal composition or periphyton biomass.

scholarly journals On the role of local depth and latitude on surface warming heterogeneity in the Laurentian Great Lakes

Inland Waters ◽  
2021 ◽  
pp. 1-15
Author(s):  
Elisa Calamita ◽  
Sebastiano Piccolroaz ◽  
Bruno Majone ◽  
Marco Toffolon
Keyword(s):  
Great Lakes ◽  
Laurentian Great Lakes ◽  
Surface Warming ◽  
Local Depth

scholarly journals Role of carbon allocation efficiency in the temperature dependence of autotroph growth rates

2018 ◽  
Vol 115 (31) ◽  
pp. E7361-E7368 ◽  
Author(s):  
Bernardo García-Carreras ◽  
Sofía Sal ◽  
Daniel Padfield ◽  
Dimitrios-Georgios Kontopoulos ◽  
Elvire Bestion ◽  
...  
Keyword(s):  
Growth Rate ◽  
Temperature Dependence ◽  
Growth Rates ◽  
Carbon Allocation ◽  
Thermal Sensitivity ◽  
Potential Growth ◽  
Allocation Efficiency ◽  
Population Growth Rates ◽  
Performance Curves

Relating the temperature dependence of photosynthetic biomass production to underlying metabolic rates in autotrophs is crucial for predicting the effects of climatic temperature fluctuations on the carbon balance of ecosystems. We present a mathematical model that links thermal performance curves (TPCs) of photosynthesis, respiration, and carbon allocation efficiency to the exponential growth rate of a population of photosynthetic autotroph cells. Using experiments with the green alga, Chlorella vulgaris, we apply the model to show that the temperature dependence of carbon allocation efficiency is key to understanding responses of growth rates to warming at both ecological and longer-term evolutionary timescales. Finally, we assemble a dataset of multiple terrestrial and aquatic autotroph species to show that the effects of temperature-dependent carbon allocation efficiency on potential growth rate TPCs are expected to be consistent across taxa. In particular, both the thermal sensitivity and the optimal temperature of growth rates are expected to change significantly due to temperature dependence of carbon allocation efficiency alone. Our study provides a foundation for understanding how the temperature dependence of carbon allocation determines how population growth rates respond to temperature.

Influence of Water Temperature on the Growth Rate of the Landlocked Sea Lamprey (Petromyzon marinus) and the Associated Rate of Host Mortality

1977 ◽  
Vol 34 (9) ◽  
pp. 1373-1378 ◽  
Author(s):  
G. J. Farmer ◽  
F. W. H. Beamish ◽  
P. F. Lett
Keyword(s):  
Growth Rate ◽  
Great Lakes ◽  
Water Temperature ◽  
Growth Rates ◽  
Petromyzon Marinus ◽  
Sea Lamprey ◽  
Instantaneous Growth ◽  
Exponential Decline ◽  
Influence Of Water ◽  
Host Mortality

Groups of sea lampreys (Petromyzon marinus) of 10–90 g initial weight were held at temperatures of 1–20 °C for 30 days and allowed to feed ad lib. on white suckers (Catostomus commersoni). Increases in water temperature and in lamprey size caused the rate of host mortality to increase in agreement with observations that mortality in the Great Lakes is seasonal. Instantaneous growth rates were maximal at 20 °C for lampreys of 10–30 g, the optimal temperature for growth shifting to 15 °C for larger lampreys of 30–90 g. Growth rates were intermediate at 10 °C and lowest at 4 °C for lampreys of all size. Accordingly, host mortality increased with temperature over the 4–20 °C range. At all experimental temperatures, increases in lamprey weight were accompanied by an exponential decline in instantaneous growth rates, a phenomenon also observed for teleosts. Laboratory growth rates at temperatures of 5–15 °C were comparable to rates observed for lampreys in Lake Huron between April and November and agree with the observation that lampreys feed in deeper waters between April and June before moving to warmer, shallower waters during the summer when growth rate increases. Key words: sea lamprey, white sucker, host, temperature, growth, Great Lakes, mortality

scholarly journals The Role of Predator Removal by Fishing on Ocean Carbon Dynamics

2021 ◽  
Author(s):  
Richard Stafford ◽  
Zach Boakes ◽  
Alice E. Hall ◽  
Georgia C. A. Jones
Keyword(s):  
Trophic Level ◽  
Carbon Dynamics ◽  
Predatory Fish ◽  
Predator Removal ◽  
Phytoplankton Communities ◽  
Total Fish ◽  
Ocean Carbon ◽  
Ocean Sequestration ◽  
Global Carbon

AbstractTotal ocean carbon exceeds 40,000 GT either dissolved in the water column or buried in ocean sediments, and the ocean continues to sequester carbon from the atmosphere. Selective removal of predatory fish through extractive fishing alters the community structure of the ocean. This altered community results in increased biomass of more productive, low trophic level fish, higher overall fish respiration rates and lower carbon sequestration rates from fish, despite possible decreases in total fish biomass. High-pressure fishing on high trophic level fish, a globally occurring phenomenon, may result in as much as a 19% increase in respiration from fish communities overall. This increase in respiration will reduce sequestration rates and could prove highly significant in global carbon budgets. Preliminary estimates suggest a loss of sequestration equating to around 90Mt C.year−1 (~ 10% of total ocean sequestration or ~ 1% of anthropogenic fossil fuel emissions per year). Ultimately, to reduce these carbon emissions, fishing needs to be carbon optimised, alongside other fisheries management outcomes, which may mean that fewer higher trophic level fish are removed. This study highlights the potential magnitude of fishing on ocean carbon dynamics and presents the key uncertainties (including understanding the effects of fishing on zoo- and phytoplankton communities) we need to urgently research to accurately quantify the effects and model future fishing practices. Graphical Abstract

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