Dependencies of Food Web and Nutrient Cycling Dynamics on Dissolved Organic Matter (DOM) and Inorganic Nutrient Concentrations in Lake Enclosures PDF Download
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Author: Erinn Honor Radomske Publisher: ISBN: Category : Lake ecology Languages : en Pages : 0
Book Description
"An autotrophic-allotrophic gradient was established in 12 lake enclosures across a natural DOM concentration gradient. Phytoplankton were co-regulated by solar irradiance and inorganic nutrient concentrations, whereas bacterioplankton were strongly dependent on DOM in the reference enclosures. Nutrient scavenging in the reference enclosures was limited by efficient biotic incorporation and recycling, across the full DOM gradient. Nutrient enrichment stimulated a strong autotrophic response across the autotrophic-allotrophic gradient due to increased phytoplankton productivity. Bacterioplankton productivity was still strongly dependent on DOM, but bacterioplankton productivity also increased either as a direct or indirect result of nutrient enrichment. Carbon, nitrogen, and phosphorus were effectively scavenged from the water column by incorporation into biomass at high rates and then deposited in the sediments in the nutrient enriched enclosures, producing nutrient-rich sediments. The data further suggest that at DOM concentrations greater than 14 mg L -1, allotrophy would dominate regardless of inorganic nutrient enrichment."--Page ii.
Author: Erinn Honor Radomske Publisher: ISBN: Category : Lake ecology Languages : en Pages : 0
Book Description
"An autotrophic-allotrophic gradient was established in 12 lake enclosures across a natural DOM concentration gradient. Phytoplankton were co-regulated by solar irradiance and inorganic nutrient concentrations, whereas bacterioplankton were strongly dependent on DOM in the reference enclosures. Nutrient scavenging in the reference enclosures was limited by efficient biotic incorporation and recycling, across the full DOM gradient. Nutrient enrichment stimulated a strong autotrophic response across the autotrophic-allotrophic gradient due to increased phytoplankton productivity. Bacterioplankton productivity was still strongly dependent on DOM, but bacterioplankton productivity also increased either as a direct or indirect result of nutrient enrichment. Carbon, nitrogen, and phosphorus were effectively scavenged from the water column by incorporation into biomass at high rates and then deposited in the sediments in the nutrient enriched enclosures, producing nutrient-rich sediments. The data further suggest that at DOM concentrations greater than 14 mg L -1, allotrophy would dominate regardless of inorganic nutrient enrichment."--Page ii.
Author: Keli J. Goodman Publisher: ISBN: Category : Languages : en Pages : 183
Book Description
This research combines observation, experimentation, and modeling to evaluate the influence of lakes on dissolved organic matter (DOM) quantity, quality and export in subalpine watersheds of the Sawtooth Mountain Lake District, central Idaho. First, I conducted an empirical study of the hydrologic and biogeochemical controls on DOM dynamics in stream-lake fluvial networks. I hypothesized that lakes would decrease temporal variability (i.e., buffer) and alter the characteristics of DOM from inflow to outflow. I tested these hypotheses by evaluating DOM temporal patterns and measuring annual export in seven-paired lake inflows and outflows. I then evaluated how ultraviolet (UV) exposure affected DOM characteristics during snowmelt and baseflow, and how UV alters baseflow DOM bioavailability and nutrient limitation. Given that increased water residence time increases UV exposure, I hypothesized that lake outflow DOM would be more photorecalcitrant than DOM from lake inflows. I further hypothesized that UV exposure would increase DOM quality, heterotrophic processing, and nutrient demand. Results indicate that lakes can buffer stream temporal variability by acting as a DOM sink during snowmelt and a DOM source during baseflow. Lake outflow DOM photodegradation was similar to lake inflows during snowmelt (p=0.66). Conversely, outflow DOM was 2X more photorecalcitrant than inflow DOM during baseflow (ANOVA, p=0.03) and was strongly related to water residence time (WRT). During baseflow, light exposure increased inflow and outflow DOM bioavailability (p=0.059 and 0.024, respectively) and nutrient limitation (p=0.03 and 0.09, respectively). Combined, these results indicate that WRT in subalpine lakes strongly influences DOM temporal variability and DOM degradation and processing. Thus, lakes can provide temporal stability of DOM and potentially increase both carbon and nutrient uptake by heterotrophs in lake outflows. I then evaluated how global changes could alter hydrologic and nutrient dynamics in a subalpine lake. Model results indicate that the magnitude and timing of snowmelt runoff can have a substantial effect on water and nutrient exports. In phosphorus (P)- limited lakes, increases in inorganic N concentrations within and exported from lakes are likely to occur with increased temperatures and lake WRT. Increases in atmospheric N deposition will further enhance inorganic N exports in P-limited subalpine lakes.
Author: Bryanna Sherbo Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Over the past few decades, spatial and temporal variation in concentrations of allochthonous dissolved organic carbon (DOC) has been increasing in surface waters of boreal lakes around the world with climate change. Terrestrial landscapes export large amounts of organic matter into lakes, primarily as DOC. It is understood that DOC impacts primary production through its combined effects on light and nutrient availability. However, there remains uncertainty as to the mechanisms that cause DOC to have positive or negative effects on algal productivity. In a survey of 6-7 lakes spanning a DOC gradient (3.5-9.4 mg L-1) at International Institute of Sustainable Development-Experimental Lakes Area (IISD-ELA) in northwestern Ontario, we determined the effects of DOC on whole-lake metabolism (gross primary production (GPP), respiration, and net ecosystem production (NEP)) and depth integrated net primary production (NPP). Using in situ diel free-water oxygen method and in vitro partial pressure of CO2 incubations, we found that primary production was significantly impacted by DOC. In general, the effects of DOC on algal productivity was negative, although there was some evidence for the stimulation of whole ecosystem production by nutrients at low DOC concentrations. Epilimnetic chlorophyll, GPP, and community respiration increased significantly with DOC, and total depth integrated and sub-epilimnetic NPP decreased significantly with DOC. Lakes with the highest proportion of sub-epilimnetic production had well developed deep chlorophyll maxima (DCM). DCM were negatively correlated with DOC and are viewed as ecological hotspots for higher trophic levels. DCM and sub-epilimnetic productivity were eliminated in lakes with DOC values > 7.1 mg L-1. These results substantiate the influence of allochthonous DOC on aquatic food webs and highlight the combined effects of DOC on light and nutrient availability. The association of DOC with epilimnetic nutrients caused an increase in epilimnetic GPP (chapter 2) and decreasing light availability caused a decrease in total and sub-epilimnetic NPP (chapter 3). These contrasting effects of DOC on primary production provide further insight into the balance between nutrients and light with increasing concentrations of DOC.
Author: Joseph Tonin Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Over the past few decades, terrestrially derived dissolved organic carbon (DOC) has been recognized as a fundamental driver of food web productivity in nutrient poor lakes. The mechanisms that underlie these effects remain poorly understood, particularly for higher trophic levels including zooplankton, benthic invertebrates, and fish. In a survey of eight lakes in northwestern Ontario, I determined consumer biomass and used stable isotopes of carbon, nitrogen, and hydrogen to investigate relationships between DOC and pathways of energy flow, resource and habitat availability, and consumer biomass. Using Bayesian stable isotope mixing models, I found that hypolimnetic phytoplankton were an important resource for zooplankton in low-DOC lakes. With increased DOC concentrations, light attenuation increased and chlorophyll a concentrations below the thermocline were reduced relative to epilimnetic concentrations. At higher DOC concentrations, zooplankton acquired proportionately more energy from low quality terrestrial sources. Zooplankton biomass also declined with increasing utilization of terrestrial sources (allochthony), suggesting that terrestrial organic matter suppresses zooplankton productivity through simultaneous limitations on habitat and resource availability and quality. Based on biomass, the dominant fish species across my study lakes was White Sucker (Catostomus commersonnii). Bayesian mixing models indicated that allochthony by White Suckers increased with DOC and that greater allochthony was related to lower White Sucker biomass measured as catch-per-unit-effort (bCPUE). Both White Sucker bCPUE and chironomid biomass were positively related to mean light irradiance, with the highest biomasses of fish and chironomids occurring in lakes with a higher proportion of their volume in the photic zone. White Sucker bCPUE was strongly and positively correlated with chironomid biomass, suggesting that DOC-mediated resource limitation may influence fish productivity via reduced prey availability.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Progress in research to evaluate the impact of utilization of fossil fuels on surface water is reported. Analyses of regulatory mechanisms of growth and rates of carbon cycling center on evaluation of quantitative control interactions among the microflora of the pelagial zones of several lakes of progressively greater eutrophy, littoral photosynthetic producer-decomposer complex, and allochthonous inorganic-organic influxes and their biotic processing. The underlying thesis is that quantification of the dynamic carbon fluxes among these components and their rate control mechanisms by physical and chemical factors are fundamental to elucidation of the rate functions of lake eutrophication. A major portion of the research has been directed towards the fate and nutrient mechanisms regulating qualitative and quantitative utilization and losses of organic carbon synthesized within lakes and their drainage basins. It has become increasingly apparent that the wetland and littoral flora, and attendant epiphytic and benthic microflora, have major regulatory controls on biogeochemical cycling of whole lake systems. A major effort on factors regulating the metabolism of littoral macrophytes and attached algae has been coupled to integrated studies on their decomposition and the fate of detrital dissolved and particulate organic matter. These organic products are being coupled to influences on enzymatic activity and inorganic nutrient cycling.
Author: K. Ramesh Reddy Publisher: CRC Press ISBN: 0429531931 Category : Science Languages : en Pages : 926
Book Description
The globally important nature of wetland ecosystems has led to their increased protection and restoration as well as their use in engineered systems. Underpinning the beneficial functions of wetlands are a unique suite of physical, chemical, and biological processes that regulate elemental cycling in soils and the water column. This book provides an in-depth coverage of these wetland biogeochemical processes related to the cycling of macroelements including carbon, nitrogen, phosphorus, and sulfur, secondary and trace elements, and toxic organic compounds. In this synthesis, the authors combine more than 100 years of experience studying wetlands and biogeochemistry to look inside the black box of elemental transformations in wetland ecosystems. This new edition is updated throughout to include more topics and provide an integrated view of the coupled nature of biogeochemical cycles in wetland systems. The influence of the elemental cycles is discussed at a range of scales in the context of environmental change including climate, sea level rise, and water quality. Frequent examples of key methods and major case studies are also included to help the reader extend the basic theories for application in their own system. Some of the major topics discussed are: Flooded soil and sediment characteristics Aerobic-anaerobic interfaces Redox chemistry in flooded soil and sediment systems Anaerobic microbial metabolism Plant adaptations to reducing conditions Regulators of organic matter decomposition and accretion Major nutrient sources and sinks Greenhouse gas production and emission Elemental flux processes Remediation of contaminated soils and sediments Coupled C-N-P-S processes Consequences of environmental change in wetlands# The book provides the foundation for a basic understanding of key biogeochemical processes and its applications to solve real world problems. It is detailed, but also assists the reader with box inserts, artfully designed diagrams, and summary tables all supported by numerous current references. This book is an excellent resource for senior undergraduates and graduate students studying ecosystem biogeochemistry with a focus in wetlands and aquatic systems.
Author: David C. Sigee Publisher: John Wiley & Sons ISBN: 0470026472 Category : Science Languages : en Pages : 516
Book Description
This unique textbook takes a broad look at the rapidly expanding field of freshwater microbiology. Concentrating on the interactions between viruses, bacteria, algae, fungi and micro-invertebrates, the book gives a wide biological appeal. Alongside conventional aspects such as phytoplankton characterisation, seasonal changes and nutrient cycles, the title focuses on the dynamic and applied aspects that are not covered within the current textbooks in the field. Complete coverage of all fresh water biota from viruses to invertebrates Unique focus on microbial interactions including coverage of biofilms, important communities on all exposed rivers and lakes. New information on molecular and microscopical techniques including a study of gene exchange between bacteria in the freshwater environment. Unique emphasis on the applied aspects of freshwater microbiology with particular emphasis on biodegradation and the causes and remediation of eutrophication and algal blooms.
Author: Erinn Honor Radomske
Author: Erinn Honor Radomske
Author: Keli J. Goodman
Author: Bryanna Sherbo
Author: Joseph Tonin
Author: Edward G. Stets
Author: 
Author: 
Author: Robert G. Wetzel
Author: K. Ramesh Reddy
Author: David C. Sigee