摘要:

The meromictic character of Green Lake, Jamesville, New York, is described based on a biweekly monitoring program conducted for 14 months. A sharp chemical gradient was observed in the lower waters throughout the study, supporting the classification of the lake as meromictic. An isodensity plot is presented for the study period. Densities were estimated with an equation of state obtained from the literature, which incorporated depth, temperature, and specific conductance information. Temporal variations in total stability are depicted, which were mitigated by seasonal thermal stratification. The chemical stability component remained constant (closed system value of 32.4 g-cm cm−), and contributed only 5.7% to the total, for the maximum stability case. The work of wind in distributing the summer heat income (8,570 g-cal cm−) was 348 g-cm cm−. Based on the identity of the chemically enriched forms within the chemocline/monimolimnion, the low magnitude of the chemical stability, the large seasonal contribution of thermal stability to total stability, and the lake settling, it is probable that the lake is an example of biogenic meromixis.

ISSN:0270-5060    

DOI:10.1080/02705060.1981.9664025

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The temporal and vertical distributions of inorganic carbon and related forms were assessed for the mixolimmion of Green Lake, Jamesville, NY, based on a biweekly monitoring program conducted for a 14 month period. The daily time structure of the distributions was delineated for a single diurnal cycle. Attendant [H2CO3*] ([H2CO3] + [CO2(aq)]) and calcite equilibrium conditions were determined through solution of equilibrium equations, adjusted for temperature and ionic-strength. Inorganic carbon equilibrium conditions within the ion-rich chemocline/monimollmnion were evaluated with the aid of a computer model, which incorporated ion-pair interactions, utilizing data obtained from a single sampling.

ISSN:0270-5060    

DOI:10.1080/02705060.1981.9664026

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

For several decades the thick algal scums and offensive odors of Medical Lake have limited its use. High phosphorus levels, resulting from internal cycling of the nutrient, were responsible for the excessive algal growth. Disruption of the cycle was achieved by whole-lake applications of aluminum sulfate. The treatment significantly reduced phosphorus levels, eliminated nuisance blooms and enhanced water clarity.

ISSN:0270-5060    

DOI:10.1080/02705060.1981.9664027

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The application of 936 metric tons of alum to eutrophic Medical Lake, WA in 1977 interrupted the lake's internal phosphorus cycle, lowering its trophic status. Observations of the zooplankton community were made before, during, and for three years following the restoration. A decline in percent composition of rotifers with a corresponding increase in crustaceans has occurred both in response to the altered trophic status and as a result of coexploitive interactions within the community. The Rotifera numerically comprised approximately 90 percent of the zooplankton standing crop prior to the restoration but only 43.5 percent of the standing crop in 1980. The Crustacea (i.e., Cladocera and Eucopepoda) collectively comprised 9.9 percent of the total standing crop in 1977 increasing to 56.5 percent in 1980. Indices of species diversity also indicated a trend toward a more diverse zooplankton community with less annual variability.

ISSN:0270-5060    

DOI:10.1080/02705060.1981.9664028

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Macroinvertebrate community structure is evaluated as an indicator of human enrichment of streams. Standing crops and Shannon-Wiener diversity indices, utilizing numbers of individuals and biomass, are compared with other indicators as well as the sociologically perceived condition of streams.

ISSN:0270-5060    

DOI:10.1080/02705060.1981.9664029

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Changes in the caloric content of the phantom midge,Chaoborus punctipenniswere compared in lakes of 8 m and 26 m depth. Organisms were collected monthly from March through November. Mean caloric content was 6355 and 4534 cal/g ash-free weight in the shallow and deep lake, respectively. Variation in migration distance of the organisms between the two lakes was suggested as influencing the pronounced variation in caloric content.

ISSN:0270-5060    

DOI:10.1080/02705060.1981.9664030

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

To determine how much organic nitrogen is lost from lakes during winter by natural processes, we collected water in fall and winter from six small lakes (area, 5–822 hectares) and separated organic matter dissolved in the water withn-butanol into three fractions—yellow organic acids, a white precipitate, and aqueous (nonextractable) organic matter. The nitrogen content of each fraction was measured by ultraviolet photolysis. About 25–30% of the yellow acid and white precipitate fractions were lost from the water column in each of the lakes during winter. More than 80% of the organic nitrogen dissolved in the lake water samples was found in the aqueous fraction. We believe the white precipitate is part of the humin material in lake waters because it was relatively insoluble in acidic and alkaline solutions.

ISSN:0270-5060    

DOI:10.1080/02705060.1981.9664031

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

A limnological survey was conducted on a reservoir in northeast Brasil. The data indicate that seasonal variations in plankton and macrophyte productivity are primarily functions respectively of light penetration and surface area rather than nutrient availability.

ISSN:0270-5060    

DOI:10.1080/02705060.1981.9664032

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

A Standardized Traveling Kicking Method (STKM) was tested for sensitivity to sampling personnel in collecting stream macroinvertebrates. Collections taken by different persons showed significant differences in relative standing crop in depauperate stream reaches, and minor differences for percent community composition in fauna rich reaches. The STKM appears to be an excellent, tool for monitoring community composition changes in riffle habitats, but requires further development for faunal-poor reaches of stream benthos.

ISSN:0270-5060    

DOI:10.1080/02705060.1981.9664033

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Biomass of zooplankton can be estimated from the relation between length and weight by measuring the appropriate dimension of length on individual zooplankton. Length-dry weight relationships for 15 species of freshwater crustacean zooplankton collected from the Connecticut River were determined. Length-weight equations can be used to rapidly determine the biomass of zooplankton species when it is impractical to directly measure their weights.

ISSN:0270-5060    

DOI:10.1080/02705060.1981.9664034

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor