A Simple, Sensitive Underwater Photometer1

Rich, Peter H.; Wetzel, Robert G.

doi:10.4319/lo.1969.14.4.0611

Cited by 22 publications

(9 citation statements)

References 4 publications

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“…Sediment organic matter was measured by combustion of six sieved (2-mm mesh), dried sediment samples at 550'C and sediment pH was determined by electrometric methods (Chapman 1976). Light measurements were made at midday at 10 locations within a habitat at several heights above the ground using a hemispherical photometer (Rich and Wetzel 1969).…”

Section: Methodsmentioning

confidence: 99%

Phenotypic and Genotypic Components of Growth and Reproduction in Typha Latifolia: Experimental Studies in Marshes of Differing Successional Maturity

Grace¹,

Wetzel²

1981

Ecology

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The objective of this study was to separate the genotypic and phenotypic variation in biomass allocation for populations of Typha latifolia from habitats of differing successional maturity. Field studies revealed that the OPEN marsh population of T. latifolia suffered high levels of ramet mortality over winter and had rapid growth in ramet numbers during the growing season. In contrast, the WOODS marsh population suffered predominantly from growing—season mortality with little ramet death over winter. The CATTAIL marsh population was intermediate in mortality patterns to the other two populations. Tissue nutrient analyses and fertilization experiments revealed that T. latifolia in the OPEN marsh was principally nutrient limited while T. latifolia in the WOODS marsh was light limited. The CATTAIL marsh population was exposed to conditions of nutrients and light intermediate to the other populations. Field studies of 14C fixation and allocation showed that both sexual and vegetative reproduction consisted of greater percentages of biomass production in the OPEN marsh population than in the CATTAIL or WOODS marsh populations. Ramets in the CATTAIL and WOODS marsh populations allocated a greater percentage of their fixed carbon to growth of the parent ramet. Allocation to roots was greatest in the OPEN marsh population and experiments showed this response to result from low nutrient availability. Leaf biomass was a fixed percentage of the total biomass under all conditions but the leaf volume:leaf mass ratio was greatest in the WOODS marsh population. Experiments revealed that the differences in leaf volume:mass were principally the result of light availability, but that decreased wind exposure also contributed to the high leaf volume:mass ratio. Difference in biomass allocation under uniform garden conditions indicated biotypic differences among populations such that habitats exposed to high levels of disturbance contained biotypes with high allocation to sexual reproduction. In contrast, the biotype from the habitat with the most intense level of density stress (WOODS—CATTAIL marsh biotype) allocated more biomass to root production, a trait potentially important for competition. Transplantation of biotypes into natural habitats showed that under nutrient—limiting conditions the WOODS—CATTAIL marsh biotype was more productive than the OPEN marsh biotype. This difference resulted from differences in allocation patterns whereby the OPEN biotype allocated a greater percentage of biomass to rhizome storage for sexual reproduction and the WOODS—CATTAIL biotype allocated more to root growth. Under light—limiting conditions no differences in productivity between biotypes occurred. It is concluded that both genotypic and phenotypic variation in biomass allocation contribute to the growth and reproduction of T. latifolia over a broad range of habitats differing in successional maturity. _kw biotypes

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Section: Methodsmentioning

confidence: 99%

Phenotypic and Genotypic Components of Growth and Reproduction in Typha Latifolia: Experimental Studies in Marshes of Differing Successional Maturity

Grace¹,

Wetzel²

1981

Ecology

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“…Temperature and dissolved oxygen profiles were determined with a Hydrolab R (System 8000 or Surveyor 11) at 2-m intervals. Vertical light transmission profiles were made using a Protomatic R (designed after Rich and Wetzel 1969) underwater photometer at 1-m intervals to a depth of 1% surface light intensity.…”

Section: Data Collectionmentioning

confidence: 99%

Relationship between Phytoplankton Volume and Rainbow Trout—Daphnia pulexInteractions after Phosphorus Inactivation, Medical Lake, Washington

Geist

Scholz

Soltero

1993

Journal of Freshwater Ecology

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Fisheries and limnological investigations in post-restoration Medical Lake, Washington, suggest that establishing a successful rainbow trout Oncorhvnchus m v W fishery depends on the maintenance of a healthy Q!,&x population and that phytoplankton volume is related to interactions between rainbow trout and B M. As rainbow trout abundance increases, & standing crop decreases. This change results in an increase in phytoplankton standing crop. Multiple regression analyses on eight years of data was used to determine the statistical relationship between rainbow trout -B ~ulex interactions, total phosphorus levels, and phytoplankton volume. Seasonal variation in phytoplankton volume correlated more closely to rainbow trout -D, pulex interactions than did monthly vilriations in algal biomass. Accounting for the lag in response time between the independent variables and phytoplankton volume improved the percentage of explained variance. The results indicate that the variance in seasonal phytoplankton standing crop is primarily a function of rainbow trout -P. & population dynamics. Considerable debate has focused on the importance of producers versus consumers (bottom-up versus top-down forces) in regulating the relative abundance of plants and animals in each trophic level of the lentic ecosystem (Carpenter et d. 1985, Post and

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“…Light intensity was measured with an underwater photometer (Rich and Wetzel 1969) with maximum sensitivity at 5 15 nm. I converted from lux to PW cme2 using Strickland's ( 19 5 8) conversion: 1 lux = 0.15 PW cm-2.…”

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confidence: 99%

Regulation of cladoceran filtering rates in nature by body size, food concentration, and diel feeding patterns1

Haney

1985

Limnology & Oceanography

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Relationships of body length (L) and filtering rate (fl of four Daphnia species and Holopedium gibber-urn were examined in situ during the day' and night, During the day filtering rates were low and variable. At night filtering rates were higher and more consistent, with large animals filtering at disproportionately high rates. This resulted in regressions of log F vs. log L with intercepts, slopes, and correlation coefficients that were generally lower in the day than at night. Feeding rates u) of Daphnia were calculated with seston ~3 1 pm dry weight as a measure of fcod concentration (c). There were striking differences in the day and night response of feeding rates to food concentration. In the day Daphnia feeding rates increased slowly with increasing food level, reaching fmsX at a relatively high incipient limiting food concentration (ILC), whereas at night feeding rates rose rapidly with food concentration to a maximum about twice the day.&,,, at about half the day ILC. Multiple regression equations were developed to predict F from L and C. Exceptionally high filtering and feeding rates shortly after the upward migration of Daphnia may be due to a daily hunger cycle, although hunger alone does not account for the high filtering activity sustained throughout the night. Diel feeding patterns of large and small D. pulex were asynchronous, resulting in a reversal of the F:L relationship in the early morning when small animals filtered more rapidly than did large animals.One goal of research on the feeding activities of zooplankton is to estinlate the grazing intensity of zooplankton communities. In situ methods have been applied to measure the rate of seston removal by zooplankton (Nauwerck 1963;Gliwicz 1970;Haney 1973; Roman and Rublee 198 1). Such grazing rate estimates are useful in evaluating instantaneous flux rates within a particular system, but have uncertain predictive value for other conditions.Most information on feeding relationships of freshwater zooplankton comes from laboratory experiments with Daphnia. The influence of body size and food concentration have been well defined in these experiments. However, since in nature zooplankton are subjected to fluctuations of numerous other factors, such as temperature, light, pH, hunger, and time, which may also effect feeding rates (see Hall et al. 1976), it is difficult to extrapolate from the laboratory to the field.In one of the few detailed studies of zooplankton feeding relationships based on in L Support for this study provided by National Science Foundation grant GB-366SO and Water Resources Research Office contract A-044-NH. situ measurements, Downing and Peters (1980) developed a polynomial regression model of body size, food concentration, and filtering rate for the littoral cladoceran Sida crystdina and found that feeding behavior of Sida is more complex than laboratory studies suggest. Comparable in situ tests of these relationships for limnetic zooplankton are lacking. Additional complexity in zooplankton feeding may be imposed by ...

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A Simple, Sensitive Underwater Photometer1

Cited by 22 publications

References 4 publications

Phenotypic and Genotypic Components of Growth and Reproduction in Typha Latifolia: Experimental Studies in Marshes of Differing Successional Maturity

Phenotypic and Genotypic Components of Growth and Reproduction in Typha Latifolia: Experimental Studies in Marshes of Differing Successional Maturity

Relationship between Phytoplankton Volume and Rainbow Trout—Daphnia pulexInteractions after Phosphorus Inactivation, Medical Lake, Washington

Regulation of cladoceran filtering rates in nature by body size, food concentration, and diel feeding patterns1

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