Seasonal and interannual variability in the taxonomic composition and production dynamics of phytoplankton assemblages in Crater Lake, Oregon

McIntire, C. David; Larson, Gary L.; Truitt, Robert E.

doi:10.1007/978-1-4020-5824-0_11

Cited by 7 publications

(18 citation statements)

References 25 publications

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“…One possible explanation for lower average blue attenuation since 1992 (excluding storm-related peak in 1995) is the improvement to sewage disposal at the tourist facilities in 1991 (Larson, 2002). This hypothesis is considered unsupported by phytoplankton data by McIntire et al (2007), and is also not supported by optical measurements once the pattern of rising attenuation in the early 1980s is placed into a longer time context (Fig. 16b).…”

Section: Decadal Changes In Uv Transparencymentioning

confidence: 79%

Ultraviolet radiation and bio-optics in Crater Lake, Oregon

et al. 2007

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Crater Lake, Oregon, is a mid-latitude caldera lake famous for its depth (594 m) and blue color. Recent underwater spectral measurements of solar radiation (300-800 nm) support earlier observations of unusual transparency and extend these to UV-B wavelengths. New data suggest that penetration of solar UVR into Crater Lake has a significant ecological impact. Evidence includes a correlation between water column chlorophyll-a and stratospheric ozone since 1984, the scarcity of organisms in the upper water column, and apparent UV screening pigments in phytoplankton that vary with depth. The lowest UV-B diffuse attenuation coefficients (K d,320 ) were similar to those reported for the clearest natural waters elsewhere, and were lower than estimates for pure water published in 1981. Optical proxies for UVR attenuation were correlated with chlorophyll-a concentration (0-30 m) during typical dry summer months from 1984 to 2002. Using all proxies and measurements of UV transparency, decadal and longer cycles were apparent but no long-term trend since the first optical measurement in 1896.

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Section: Decadal Changes In Uv Transparencymentioning

confidence: 79%

Ultraviolet radiation and bio-optics in Crater Lake, Oregon

et al. 2007

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“…5). Moreover, the samples in Cluster 4 from the upper part of the lake roughly corresponded to a period (1986)(1987)(1988)(1989) of maximum chlorophyll concentration in the lake (McIntire et al, 2007). Therefore, we suggest that the slightly higher concentrations of plant nutrients detected in the samples of Cluster 4 may have been associated with a period of relatively high autotrophic production in the upper 200 m of the lake.…”

Section: Discussionmentioning

confidence: 77%

“…The relatively high turbidity in the epilimnion may have been associated with high densities of phytoplankton (McIntire et al, 2007) and undetermined abiotic particles originating from the atmosphere, intracaldera springs and streamlets, and nearshore erosion of lake sediments. Beneath the epilimnion the lake decreased in turbidity and then increased near the lake bottom from the deposition of particles from the water column and the flux of particles from the edges of the lake that move down along the steep slopes into the deep lake (Dymond et al, 1996).…”

Section: Discussionmentioning

confidence: 98%

Thermal, chemical, and optical properties of Crater Lake, Oregon

Larson¹,

Hoffman²,

McIntire

et al. 2007

Hydrobiologia

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Crater Lake covers the floor of the Mount Mazama caldera that formed 7700 years ago. The lake has a surface area of 53 km 2 and a maximum depth of 594 m. There is no outlet stream and surface inflow is limited to small streams and springs. Owing to its great volume and heat, the lake is not covered by snow and ice in winter unlike other lakes in the Cascade Range.The lake is isothermal in winter except for a slight increase in temperature in the deep lake from hyperadiabatic processes and inflow of hydrothermal fluids. During winter and spring the water column mixes to a depth of about 200-250 m from wind energy and convection. Circulation of the deep lake occurs periodically in winter and spring when cold, near-surface waters sink to the lake bottom; a process that results in the upwelling of nutrients, especially nitrate-N, into the upper strata of the lake. Thermal stratification occurs in late summer and fall. The maximum thickness of the epilimnion is about 20 m and the metalimnion extends to a depth of about 100 m. Thus, most of the lake volume is a cold hypolimnion. The year-round near-bottom temperature is about 3.5°C. Overall, hydrothermal fluids define and temporally maintain the basic water quality characteristics of the lake (e.g., pH, alkalinity and conductivity). Total phosphorus and orthophosphate-P concentrations are fairly uniform throughout the water column, where as total Kjeldahl-N and ammonia-N are highest in concentration in the upper lake. Concentrations of nitrate-N increase with depth below 200 m. No long-term changes in water quality have been detected. Secchi disk (20-cm) clarity varied seasonally and annually, but was typically highest in June and lowest in August. During the current study, August Secchi disk clarity readings averaged about 30 m. The maximum individual clarity reading was 41.5 m in

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“…Hargreaves et al (2007) also hypothesized that increasing UV-B radiation over this same period might inhibit the phytoplankton, as correlated with a drop in Chl-a, which may also impact primary productivity. Temporal changes in species composition, density, and biomass of the phytoplankton assemblages were not clearly linked with those of the zooplankton assemblage (see McIntire et al, 2007).…”

Section: Biological Componentsmentioning

confidence: 96%

Long-term limnological research and monitoring at Crater Lake, Oregon

Larson¹,

Collier

Buktenica

2007

Hydrobiologia

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Crater Lake is located in the caldera of Mount Mazama in Crater Lake National Park, Oregon. The lake has a surface area of about 53 km 2 at an elevation of 1882 m and a maximum depth of 594 m. Limited studies of this ultraoligotrophic lake conducted between 1896 and 1981, lead to a 10-year limnological study to evaluate any potential degradation of water quality. No long-term variations in water quality were observed that could be attributed to anthropogenic activity. Building on the success of this study, a permanent limnological program has been established with a long-term monitoring program to insure a reliable data base for use in the future.Of equal importance, this program serves as a research platform to develop and communicate to the public a better understanding of the coupled biological, physical, and geochemical processes in the lake and its surrounding environment. This special volume represents our current state of knowledge of the status of this pristine ecosystem including its special optical properties, algal nutrient limitations, pelagic bacteria, and models of the inter-relationships of thermal properties, nutrients, phytoplankton, deep-water mixing, and water budgets.

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Seasonal and interannual variability in the taxonomic composition and production dynamics of phytoplankton assemblages in Crater Lake, Oregon

Cited by 7 publications

References 25 publications

Ultraviolet radiation and bio-optics in Crater Lake, Oregon

Ultraviolet radiation and bio-optics in Crater Lake, Oregon

Thermal, chemical, and optical properties of Crater Lake, Oregon

Long-term limnological research and monitoring at Crater Lake, Oregon

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