Charles R. Goldman

University of California, Davis | UCD · Environmental Science and Policy, World Water and Climate Foundation

Introduction and background Historic climate trends in the Tahoe Basin Modeling the impacts of future climate change Impacts on the watershed Impact on the lake Reducing negative impacts Summary and conclusions Acknowledgements References

Effects of global warming on the physical, chemical, ecological structure and function and biodiversity of freshwater ecosystems are not well understood and there are many opinions on how to adapt aquatic environments to global warming in order to minimize the negative effects of climate change. Climatic Change and Global Warming of Inland Waters p...

Molybdenum (Mo) is an essential micronutrient for biological assimilation of nitrogen gas and nitrate because it is present in the cofactors of nitrogenase and nitrate reductase enzymes. Although Mo is the most abundant transition metal in seawater (107 nM), it is present in low concentrations in most freshwaters, typically <20 nM. In 1960, it was...

Cattle grazing is believed to have a harmful impact on high elevation Sierra Nevada mountain (Sierra) watersheds. During normal precipitation years, the prevalence of suspended stream and small lake aquatic coliforms and E. coli is significantly increased in cattle-grazed areas, and periphytic algae biomass is amplified. In addition, large numbers...

We evaluated periphytic algal and microbial communities to assess the influence of human and cattle impact on Sierra water quality. 64 sites (lakes and streams from Lake Tahoe to Sequoia National Park, California) were sampled for suspended indicator bacteria and algae following standardized procedures. The potential for nonpoint pollution was divi...

The natural history and ecology of the freshwater crayfish Pacifastacus leniusculus was investigated in Lake Tahoe for 1 yr. Growth of individual groups varied between three different transects (I, II, and III). The mean size of carapace of adult crayfish trapped on Transects II and III was greater than those trapped at Transect 1. Linear regressio...

The role of kokanee salmon (Oncorhynchus nerka) carcass decomposition in the nutrient cycles and energy flow of a subalpine stream was investigated during a season (1970–71) of high spawner abundance and a season (1972–73) of low spawner abundance with a December storm flushing the stream of carcasses. Primary production, periphyton biomass, hetero...

Introductions of opossum shrimp (Mysis relicta) and kokanee salmon (Oncorhynchus nerka) are common management tools for improvement of local sport fisheries. This paper summarizes published information from varied sources and presents supplemental data on the impact of these introductions on the Lake Tahoe zooplankton and fish communities. Concomit...

In a 3-year study of Castle Lake, California, potential nutrient (N,P) limitation of phytoplankton growth occurred rapidly (within 1–4 d of ice-out). Both N and P acted as potential limiting factors to phytoplankton growth in short-term (4–5 d) bioassays. Phytoplankton responded strongly to single additions of N or P in 1990 and 1992 but weakly so...

On July 14, 1991, approximately 70 000 L of the soil fumigant Vapam®, metam sodium, was spilled into the upper Sacramento River, California. Twelve hours before this spill reached Shasta Lake we sampled several sites in a subsequently impacted area and two control stations. Thereafter, samples were collected at approximately 5-d intervals for 26 d....

Algal bioassays using stream water additions from seven Lake Tahoe basin mountain creeks were used to assess short-term bioavailability of stream P to Lake Tahoe phytoplankton during the 1996 spring snowmelt. Results indicate that 75-90% of bioassay response is due to nutrients in the <0.45-µm range. Lake Tahoe phytoplankton are primarily P limited...

Spatial heterogeneity of nutrients, particulate matter, and chlorophyll were examined in Pyramid Lake during a dry period. In May 1991, variations in constituent concentrations were associat ed with shallow regions (chlorophyll), upwelling regions (nitrate), and river inflow (silicate and total P). However, only the spatial pattern of elevated sili...

The response of Lake Tahoe water to macronutrient supplementation has been assayed with inorganic 14C uptake since the 1960s. On the decadal scale, a change in bioassay response to macronutrient enrichment took place around 1980, with a decrease in the frequency of N stimulation and an increase in the frequency of P stimulation. On the annual scale...

A systematic evaluation of limnological and experimental indicators of nutrient limitation in Pyramid Lake during 1989–92 clearly show that N is the nutrient most limiting to phytoplankton. This conclusion is supported by dissolved inorganic nutrient ratios, seston elemental composition, nutrient enrichment bioassay experiments, and blooms of N2-fi...

The uptake rates of 15NO3 and 14CO2 by the natural phytoplankton community at Castle Lake, California, were measured in situ as responses to 5 μg∙L−1 additions of molybdenum. Stimulation of both nitrate uptake and photosynthesis occurred in water samples containing only relatively high amounts of nitrate. This response to added molybdenum disappear...

Mysis relicta was fed Epischura nevadensis late instars or Diaptomus tyrrelli males in a series of feeding experiments. Mysis clearance rates were not affected by the time of day mysids were collected, the time of day experiments were conducted, or conditioning of experimental water by predators and prey. Mysis fed as efficiently in the dark as in...

Vertical profiles of chlorophyll concentration measured during 1980 in Castle Lake showed that a deep maximum developed immediately after ice thaw and persisted in the deep basin of the lake until autumn overturn. In the early portion of the ice-free season, low epilimnetic turbidity allows enough light to reach this deep-chlorophyll layer to produ...

Copepod species showed large differences in the ingestion of Microcystis cells, but no difference among microcystin producing (MC+) or lacking (MC-) strains in a short feeding experiment. Differences in selective feeding may allow some copepods to better tolerate Microcystis.

1. Increasing blooms of Microcystis aeruginosa have unknown impacts on the copepods Eurytemora affinis and Pseudodiaptomus forbesi, which are the dominant zooplankters and key prey species for endangered larval fish in the upper San Francisco Estuary. 2. Laboratory feeding experiments were designed to measure the effect of Microcystis on copepod su...

The Sierra Nevada Mountain range serves as an important source of drinking water for the State of California. However, summer cattle grazing on federal lands affects the overall water quality yield from this essential watershed as cattle manure is washed into the lakes and streams or directly deposited into these bodies of water. This organic pollu...

The literature indicates a strong correlation between inundation of previously oxidized soils, as can occur on a floodplain, and increased microbial methylation of mercury. There is special concern over the potential for increased methylmercury levels in the Yolo Bypass, a 24,000-ha floodplain for California's Sacramento River and its tributaries....

SUMMARY 1. Increasing blooms of Microcystis aeruginosa have unknown impacts on the copepods Eurytemora affinis and Pseudodiaptomus forbesi, which are the dominant zooplankters and key prey species for endangered larval fish in the upper San Francisco Estuary. 2. Laboratory feeding experiments were designed to measure the effect of Microcystis on co...

Eleven of 41 brands of skin whiteners that were collected in Phnom Penh, Cambodia, and processed with a screening kit contained more than 2000 μg/g mercury. Risk analysis indicates that these 11 brands were toxic. Nine of 19 of these skin whiteners analyzed with cold vapor atomic absorption (CVAA) spectrophotometry exceeded Association of Southeast...

This study investigates the toxicity and post-exposure effects of dissolved microcystin (MC-LR) on the dominant copepods of the upper San Francisco Estuary (SFE), where blooms of the toxic cyanobacteria Microcystis aeruginosa coincide with record low levels in the abundance of pelagic organisms including phytoplankton, zooplankton, and fish. The po...

We measured extension rates across Lake Tahoe Basin for the last 60 ka. based on measured displacement of offset marker surfaces across three active faults beneath Lake Tahoe. Seismic chirp imaging with submeter accuracy, together with detailed multibeam and light detection and ranging (LIDAR) - derived bathymetry, was used to measure fault offset,...

Pinpointing erosional ‘hot spots’ or sediment source areas within a watershed can be difficult because of the highly non-linear and episodic nature of effective runoff and sediment transport. Continuous monitoring of stream networks can provide insight into sediment source areas not possible from routine sampling by capturing episodic events and in...

Eleven of 41 brands of skin whiteners that were collected in Phnom Penh, Cambodia, and processed with a screening kit contained more than 2000 µg/g mercury. Risk analysis indicates that these 11 brands were toxic. Nine of 19 of these skin whiteners analyzed with cold vapor atomic absorption (CVAA) spectrophotometry exceeded Association of Southeast...

The relation between phyloplankton chlorophyll a and adenosine triphosphate (ATP) was investigated during a yearly cycle in Lake Tahoe, California–Nevada, and a variety of North American and New Zealand lakes of ranging trophic state. Since cellular concentrations of ATP have been shown as acceptable indicators of live biomass among natural microbi...

ABSTRACTA routine sampling technique has been developed using artificial styrofoam substrate to estimate benthic algal productivity in the littoral zone of lakes. Estimation of maximum carbon fixed in Lake Tahoe ranged from 11.1 mg C·m−2· day−1 at 0.5 m to 17.1 mg C·m−2· day−1 at 1.0 m. Estimates were made for communities composed of both diatom an...

To predict Daphnia secondary productivity along a trophic gradient indexed as total phosphorus (TP) concentration, we estimated energy transfer efficiencies from food quality for Daphnia such as eicosa-pentaenoic acid (EPA) or docosahexaenoic acid (DHA) content. Eleven flow-through Daphnia magna growth experiments were conducted with seston from 9...

The Tahoe City Wetland Treatment System (TCWTS) was constructed in 1997 to treat stormwater runoff from 23 ha of commercial, highway, and residential land use in the Lake Tahoe Basin. This subalpine, constructed, surface flow wetland treatment system consists of two cells in series, with a design water surface area of about 0.6 ha. Water quality mo...

ABSTRACT Atmospheric scientists have predicted that large-scale climatic changes will result from increasing levels of tropospheric CO2 We have investigated the potential effects of climate change on the primary productivity of Castle Lake, a mountain lake in Northern California. Annual algal productivity was modeled empirically using 25 years of l...

The fate and effect of sodium chloride applied to Californian highways in the Lake Tahoe, Truckee River, and Yuba River watersheds were studied over a period of 14 months in 1974–75. Chloride levels in streams below major freeways were found to be elevated during the winter. The high chloride levels occurred after the application of salt to roads,...

The efficacy of in-stream nephelometric turbidometry as a surrogate for total suspended solids (TSS) and total phosphorus (TP) concentrations was evaluated for use in low turbidity (<50 NTU) subalpine watersheds at Lake Tahoe, California–Nevada, USA. Continuous turbidity records for the 1999, 2000 and 2001 snowmelt seasons and data from water quali...

Although the study of lakes has traditionally focused on pelagic production pathways, recent stable isotope and diet evidence indicates that benthic algal production is an important contributor to fish production. This has led to the suggestion that energy may be more efficiently passed along benthic food chains relative to their pelagic counter- p...

We conducted a series of experiments feeding Daphnia pulex nine different phytoplankton monocultures with widely varying fatty acid composition and nutritional values to test the extent to which Daphnia fatty acid composition was affected by diet. In general, Daphnia fatty acid composition matched that of their diet much more closely than it did th...

We investigated the effects of climate variability on the thermal structure of Lake Tahoe, California-Nevada, 1970–2002, and with principal components analysis and step-wise multiple regression, related the volume-weighed average lake temperature to trends in climate. We then used a 1-dimensional hydrodynamic model to show that the observed trends...

1. The influence of temperature on in vivo photosynthetic and in vitro respiratory electron transport system (ETS) activity was determined over the season for the 3 m (warm-water) and a 20m (cold-water) phytoplankton communities in Castle Lake. The optimum temperature of photosynthesis at 3 m (X̄=20.8°C) was significantly higher than the average op...

An additive semi-analytic model of water clarity for the forward problem of calculating apparent optical properties (AOPs) of diffuse attenuation and Secchi depth from the inherent optical properties (IOPs) due to suspended matter in oligotrophic waters is presented. The model is general in form, taking into account algal concentration, suspended i...

We investigated the effects of cultural eutrophication on the coupling between pelagic primary producers and benthic consumers in Lake Tahoe. Spatial and temporal changes in zoobenthos energetics were documented by measuring .40 yr of change in pelagic primary production through 14 C incubations, reduction in clarity by Secchi and light measurement...

Vertical profiles of seston food quality and quantity were measured in subalpine Castle Lake for particulate carbon, chlorophyll a, fatty acids and phosphorus in addition to abiotic parameters including water temperature and dissolved oxygen levels. Field and laboratory incubation experiments were employed to manipulate Daphnia rosea growth environ...

We analyzed a 42-yr record of primary productivity in small, subalpine Castle Lake to determine how climatic variability might influence lake primary productivity. A Pacific Decadal Oscillation (PDO) polarity reversal in 1977 significantly affected winter air and summer water temperatures in Castle Lake. The timing of lake ice-out was explained by...

Determining the factors that control food web interactions is a key issue in ecology. The empirical relationship between nutrient loading (total phosphorus) and phytoplankton standing stock (chlorophyll a) in lakes was described about 30 years ago and is central for managing surface water quality. The efficiency with which biomass and energy are tr...

We developed a time series model of Secchi depth for Lake Tahoe incorporating a mechanistic understanding of interannual variability with sufficient simplicity to allow data-based parameter estimation. Secchi depth is still occasionally over 40 m at Lake Tahoe, but mean annual Secchi depth has declined nearly 10 m since 1967, prompting a large-scal...

To investigate the potential for heterotrophic organisms to upgrade the food quality of seston, we per- formed decay experiments using a non-toxic Microcystis aeruginosa (cyanobacteria) monoculture. The experiment was performed in darkness with aeration using a microbial inoculum collected from a hypereutrophic pond. Chlorophyll a concentrations de...

We examined whether seston food quality was a significant factor to predict zooplankton, specifically Daphnia pulex, biomass dynamics in Lake Berryessa, California, U.S.A. The seston composition changed dramatically during the study period. Total macrozooplankton to seston biomass ratios were high during the springtime, as was D. pulex biomass. In...

Plans for the restoration of aquatic ecosystems are increasingly focusing on the restoration and rehabilitation of self-sustaining native fish communities. Such efforts have not traditionally adopted an ecosystem-based perspective, which considers species as embedded within a broader food web context. In this study, we quantify food web changes in...

Because of major biochemical imbalances between plants and animals, ecological efficiency at this interface may have a major impact on overall energy flow in ecosystems. In order to study relationships between seston food quality and energy transfer between primary producers and herbivores, we conducted five microcosm experiments in Castle Lake, Ca...

Fresh water, the most essential resource, is in increasingly short supply globally and is likely to be the cause of future conflicts. As an essential but seriously undervalued “commodity”, it should take its place among the other well-known commodities and be better managed by world governments. Aquatic ecosystems worldwide are under increasing ant...

1. A series of experiments examined growth of Daphnia magna on three algal diets (Rhodomonas minuta, Scenedesmus acutus and Synechococcus sp.) at varying physiological states [nitrogen and phosphorus (P) limitations] to test whether variation in algal fatty acid and/or elemental composition can predict Daphnia growth.2. These algae differed widely...

The sampling of streams and estimation of total loads of nitrogen, phosphorus, and suspended sediment play an important role in efforts to control the eutrophication of Lake Tahoe. We used a Monte Carlo procedure to test the precision and bias of four methods of calculating total constituent loads for nitrate-nitrogen, soluble reactive phosphorus,...

In this paper we present the analysis of a 19-year hydrological data set and continuous turbidity data collected from 1999 to 2001, for the subalpine watershed Ward Creek at Lake Tahoe, California. The long-term data set consists of discharge and suspended sediment concentrations, rainfall and snowfall. The intensive field data comes from a network...

Lake Tahoe is undergoing the initial stages of cultural eutrophication due to human alteration of the airshed and watershed. The lake's switch from nitrogen (N) to phosphorus (P) limitation has been attributed primarily to atmospheric N loading. This places an increased importance on controlling watershed movement of P to the lake. A stream water q...

In the fall of 1998 and the spring of 1999, pond enclosure studies were conducted to quantify the effects of the com- mercially available bacterial inocula Aqua-5™, BactaPur™, a 1998 formulation of LakePak™ WSP® and the algicides cop- per sulfate and diquat on phytoplankton, macroalgae, sub- mersed macrophytes, zooplankton, bacterioplankton and sed...

A close partnership between researchers, resources agencies, and community groups allows for the most effective ecological and economic approach to environmental protection and watershed management. One of the better documented examples of this type of cooperative effort comes from the Tahoe basin (CA-NV) where studies over the past four decades ha...

Rising levels of ultraviolet radiation (UVR) striking the Earth's surface have led to numerous studies assessing its inhibitory effects on phytoplankton and periphyton in aquatic systems. Mineral nutrients such as nitrogen (N) and phosphorus (P) have been shown to increase aspects of algal metabolism and compensate for UVR inhibition. An in situ su...

In an effort to characterize the spatial and temporal patterns of nitrogen concentration and load in streams of the Lake Tahoe basin, we analyzed 10 years of data from 10 streams, developing discharge-concentration relationships and total load estimates for nitrate-N, ammonium-N, and organic N. The results indicate that (1) most of the nitrate tran...

Evidence from this study suggests the existence of a significant modern source for atmospheric Hg deposition in the Sierra Nevada, on the continental west coast of the United States. Concentrations of both lead (Pb) and mercury (Hg) in the sediments of Lake Tahoe deposited prior to 1850 are similar to concentrations in the catchment bedrock, but th...

The factors that regulate energy transfer between primary producers and consumers in aquatic ecosystems have been investigated for more than 50 years. Among all levels of the food web (plants, herbivores, carnivores), the plant-animal interface is the most variable and least predictable link. In hypereutrophic lakes, for example, biomass and energy...

Monthly diel monitoring studies for phosphorus content were conducted (1995-1996 period) for multiple stations on Incline Creek, a mountain stream in the Lake Tahoe basin (California-Nevada). Large discharge and particulate P (PP) concentration fluctuations occurred during June in the early evening as snowmelt from higher elevations arrived at the...

To determine whether positive correlations between phytoplankton and bacterioplankton growth in nutrient addition experiments are due to growth coupling or growth stimulation by the same nutrients, we examined phyto- and bacterioplankton growth in a series of eleven nutrient addition (N × P) and light/dark experiments. In mesotrophic Castle Lake, t...

Vegetation dynamics of subalpine wetlands in the Sierra Nevada, California, were studied from 1988 through 1996. During this period, the region experienced a drought lasting from 1988 to 1994 and reaching its extreme in 1992. Our intention was to analyze the changes in plant species diversity, composition, and biomass, and interpret them in terms o...

Secchi depth has been measured in Lake Tahoe an average of every 12 d since July 1967. Because of the unusual clarity of the lake, Secchi depth measurement is responsive to small changes in light-attenuating particles, and the record exhibits strong variability at the seasonal, interannual, and decadal scales. Using recently developed methods of ap...

The impact of nutrient additions, zooplankton grazing and light intensity on phytoplankton net growth with depth and season was studied with five microcosm experiments in meso-oligotrophic, subalpine Castle Lake, California, during the period of summer stratification in June-September 1994. The incubations (4 day) were performed at 5 m intervals fr...

Algal bioassays using stream water additions from seven Lake Tahoe basin mountain creeks were used to assess short-term bioavailability of stream P to Lake Tahoe phytoplankton during the 1996 spring snowmelt. Results indicate that 75-90% of bioassay response is due to nutrients in the <0.45-μm range. Lake Tahoe phytoplankton are primarily P limited...

Discovery of the fuel additive methyl tert-butyl ether (MTBE) in drinking water supplies is of concern to public health officials, water suppliers, and the public. Despite recent policy decisions, few published studies exist on the concentrations, sources, and fate of MTBE in surface waters. The purpose of this study was to determine (1) the relati...

A whole-lake food web manipulation suggested that planktivorous fish can play an important role in regulating the pelagic food web structure of mesotrophic lakes. In this study, we examined the impact of golden shiners (Notemigonus crysoleucas) on zooplankton, diliates, phytoplankton and nutrients. We conducted a mesocosm experiment using treatment...

Analyses of long-term climatic and hydrological records, combined with palaeoclimatic reconst