Nutrient Deposition and Alteration of Food Web Structure in High-elevation Lakes of the Sierra Nevada PDF Download

Author: Craig E. Nelson
Publisher:
ISBN:
Category : Food chains (Ecology)
Languages : en
Pages : 92

View

Book Description

Author:
Publisher:
ISBN:
Category : Water
Languages : en
Pages : 126

View

Book Description

Author: California Water Resources Center
Publisher:
ISBN:
Category : Water resources development
Languages : en
Pages : 64

View

Book Description

Author: Andrea Michelle Heard
Publisher:
ISBN:
Category : Acid deposition
Languages : en
Pages : 146

View

Book Description
Increased inputs of nutrients and acid anions to oligotrophic mountain lakes are contributing to ANC depression, elevated nitrate concentrations, shifts in nutrient limitation, and changes in the productivity and structure of aquatic communities. A need for stricter standards based on measurable ecological effects has been identified as an important step toward the long-term protection of mountain lakes. The objectives of this research were to link atmospheric deposition with acidification and eutrophication effects, develop critical loads and nutrient criteria, and assess status and trends of Sierra Nevada lakes. Investigation of multiple proxies of deposition, climate, acidification, and eutrophication indicated that early 20th century ANC decline in a Sierra Nevada lake is attributed to atmospheric deposition and the subsequent recovery in the late 20th century is attributed to the success of the Clean Air Act. Correlation analysis indicated ANC was correlated with atmospheric deposition indicators, but was not correlated with climate measures or productivity proxies. However, analyses looking more broadly across the landscape found a correlation with present day indicators of atmospheric deposition (SCPs) and ANC. These results indicate that not all lakes have fully recovered from acid deposition and stricter regulatory standards are needed. I aimed to link atmospheric deposition indicators with effects of eutrophication and acidification at a landscape scale and found that atmospheric deposition indicators were correlated with acidification, but not with eutrophication. Quantifying the relationship between nitrogen deposition and eutrophication across complex mountain landscapes is presently challenging, leading to the conclusion that critical loads based on acidification are a more robust approach. An acidification critical load was calculated based on 20th century ANC and acid deposition patterns and is 73.9 eq ha [superscript -1] yr [superscript -1] for acid anions, which translates to 0.68 kg-N ha [superscript -1] yr [superscript -1] and 1.2 kg-SO4 ha[superscript -1] yr[superscript -1]. Nitrogen criteria were calculated and ranged from were 0.33 - 0.89 [Mu]M (10% ED), 1.0 - 4.0 [Mu]M (50% ED), and 3.1 - 18 [Mu]M (90% ED). Application of criteria to Sierra Nevada lakes indicated the 10% effective dose was exceeded by 28-37 %, the 50% effective dose was exceeded by 18-29%, and the 90% effective dose was exceeded by 0.0-21%.

Author: Regino Zamora
Publisher: Springer Nature
ISBN: 3030942198
Category : Science
Languages : en
Pages : 421

View

Book Description
This book covers the landscape, geography and environment of the Sierra Nevada in Spain. The Sierra Nevada hosted the last glaciers in southern Europe. Today, it is one of the most important centers of plant diversity in the western Mediterranean and one of the most outstanding in Europe. This massif has ideal conditions to analyze past environments as well as the effects of global change on ecosystems. This can be seen in the large number of projects that are being conducted within the umbrella of the Sierra Nevada Global Change Observatory. This book summarizes all the scientific knowledge available about this massif, from the geomorphological and ecological perspectives to the recent spatial adaptive management and Open Science initiatives. Focusing on the very sensitive mountain environment of Sierra Nevada, the book intends to be a reference for many people interested in mountain processes. The audience would include scientists from all disciplines, but it would also target on an audience beyond the academia (territorial managers, environmentalists, mountaineers, politicians, technicians, etc.).

Author: Jasmine E. Saros
Publisher:
ISBN:
Category : Diatoms
Languages : en
Pages : 10

View

Book Description
Critical loads of nitrogen (N) from atmospheric deposition were determined for alpine lake ecosystems in the western US using fossil diatom assemblages in lake sediment cores. Changes in diatom species over the last century were indicative of N enrichment in two areas, the eastern Sierra Nevada, starting between 1960 and 1965, and the Greater Yellowstone Ecosystem, starting in 1980. In contrast, no changes in diatom community structure were apparent in lakes of Glacier National Park. To determine critical N loads that elicited these community changes, we modeled wet nitrogen deposition rates for the period in which diatom shifts first occurred in each area using deposition data spanning from 1980 to 2007. We determined a critical load of 1.4 kg N ha-1 year-1 wet N deposition to elicit key nutrient enrichment effects on diatom communities in both the eastern Sierra Nevada and the Greater Yellowstone Ecosystem.

Author: Paul David Koster (II.)
Publisher:
ISBN:
Category : Aquatic ecology
Languages : en
Pages : 104

View

Book Description
I examined the trophic structure of lakes containing and lacking fish using carbon and nitrogen stable isotopes. [Delta] 15 N values revealed distinct trophic fractionation values for each type of lake. Trophic fractionation for fish-containing and fish-removed lakes was 2.03 [per thousand] ± 0.517 (n=116) and 1.76 [per thousand] ± 0.384 (n=186) respectively. Nitrogen values in fish-containing lakes species tended to be enriched relative to fish-removed lakes, suggesting increased P availability. Time-series of [Delta] 15 N for multiple species indicated small variations in nitrogen suggesting changes in diet from year to year. However significant depletion of 4.42 [per thousand] was noted for the copepod Leptodiaptomus signicauda and correlated with the reemergence of Daphnia melanica post fish removal. Computations of trophic position indicated that frogs and fish occupy the same trophic level and likely rely on the same food sources. This finding suggests that fish cause extirpation of frogs both through direct predation and competition for food resources.

Author: Celia C. Symons
Publisher:
ISBN:
Category :
Languages : en
Pages : 117

View

Book Description
Determining factors that control how biomass is distributed among plants, animals, microbes and non-living components of ecosystems is a major goal of ecology. Theoretical and empirical work have demonstrated that ecosystem structure and function may vary with the environment, but studies often overlook the role of adaptation and shifts in species composition that will occur over longer timescales relevant to climate change. For my doctoral research I used a 'natural experiment' in Sierra Nevada mountain lakes to ask questions about the strength of top-down and bottom-up forcing in a natural system where communities have assembled and adapted to differences in the environment over periods from years to millennia. In Chapter 1 I compare fish and fishless lakes along an elevational gradient, and show that an interaction between fish presence and temperature alters food web structure, ecosystem function, species and trait composition. Top-down forcing from fish on plankton biomass was stronger in warm lakes, suggesting that a warmer climate will magnify the effect of introduced predators on biomass distribution. Fish and warmer temperatures select for the same species and traits of zooplankton in lakes, suggesting that lakes containing invasive predators may be less sensitive to warming. In Chapter 2 I test this hypothesis using a large-scale community transplant experiment, where I transplanted plankton communities that assembled and evolved at different elevations and predator regimes to new elevations and the addition or removal of fish. I found that past exposure to fish caused an evolutionary response in keystone members of the zooplankton community that increased their fitness in environments without fish. This suggests that past selection can change how communities will respond to further environmental change. In Chapter 3, I show that bottom-up processes influence fish growth, with higher growth rates occurring in warmer, clearer lakes. My thesis helps to elucidate the effects of temperature and predators on physiology, evolution, species ranges and community interactions, which is necessary to forecast the response of ecosystems to climate change. My thesis integrates across these levels of organization to understand the origin of ecosystem resilience in a changing climate.

Author: Bonnie Kathleen Ellis
Publisher:
ISBN:
Category : Biological invasions
Languages : en
Pages :

View

Book Description
Monthly or more frequent measures of internal and external nitrogen and phosphorus (NP) loading to Flathead Lake, Montana, in relation to biotic response variables and attendant interactive effects associated with invasion of a nonnative amphipod, Mysis relicta were made during 1977-2004. Trends and interactions were evaluated for statistical significance using Bayesian models against null hypotheses of no effects. Aerosol deposition contributed 10.1% and 7.0% of the total annual NP load; nitrate and ammonium increased and soluble reactive phosphorus declined over the period of record. Deposition was highest during thermal inversions that entrained smoke and dust. Riverine nitrate increased and ammonium and SRP decreased. Increasing trends were coherent with increasing urbanization and forest disturbance. However, contribution of sewage treatment facilities to annual TP load decreased from 11% to 3% following improved nutrient removal technologies. Increasing primary productivity per unit chlorophyll (PP/chla) and decreasing hypolimnetic oxygen concentrations were coherent with the trends in NP loading and therefore indicative of human influences. The lake remains oligotrophic with productivity limited by availability of labile NP, although worrisome blooms of algae, including Anabaena flos-aquae, occurred several times during the period of record. Catastrophic food web change was clearly associated with the establishment of Mysis relicta. Mysids exploded to 129 m2 in 1984-86. Their intense foraging on zooplankton caused an 83% reduction in the biomass of large species. Kokanee salmon, also a zooplankton feeder, were extirpated, whereas lake trout increased from 0.09 before to 1.7 cpue after Mysis in standardized gill net catches. Lake trout expansion and zooplankton changes corresponded with an 80% decline in native salmonid fishes. Mysids declined rapidly with increasing profundal fish predation during 1987-88 and then stabilized around 40 m2. A Bayesian analysis showed that during the Mysis upheaval there was a step increase in PP of 60 mgC m-2 day-1, but no trend in the period before or after Mysis. Herbivorous zooplankton increased post-Mysis, coherently with declining chlorophyll. Increased herbivory provided persuasive explanation for increasing PP/chla. The limnological legacy of Flathead Lake is a story of changing quasi-stable states mediated by a strong interaction between nutrient loading and mysid foraging.

Author: Thomas W. Amidon
Publisher:
ISBN:
Category : Food chains (Ecology)
Languages : en
Pages : 156

View

Book Description