ISSN:0270-5060    

DOI:10.1080/02705060.1981.9664011

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Summer production estimates were made for the rotiferPolyarthra vulgarisin a northern Michigan bog lake. Egg development times for the rotifer at 15 and 21-C were 1.3 and 1.17 days respectively. The dry weight of an individual rotifer was 0.24 ug. Production ranged from 0.0 ug/L/day to 26.9 ug/L/day throughout the summer of 1977. Average production estimates forP. vulgarisduring the period were 2.34 ug/L/day using Edmondson's egg ratio method of calculation, and 4.61 ug/L/day using Galkovskaya's generation time method.

ISSN:0270-5060    

DOI:10.1080/02705060.1981.9664012

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Results of 2-years' quantitative sampling of benthic macro-invertebrates in Mink Creek are reported. Midway through the study the substratum and flow pattern were intentionally altered. The invertebrate community consisted of 90 taxa, of which Trichoptera and Plecoptera were the best represented. However, Ephemeroptera were the most important in terms of numbers and biomass. Mean density of the community increased from 7000/m2(10.8g AFDW) in year 1 to 21,000/m2(26.5g) in year 2. In spite of the apparent increase in carrying capacity of the stream in year 2, community structure as measured by species richness, diversity, equitability and relative importance at the ordinal level did not differ between years. Grazers made up 42 and 33% of total numbers and 56 and 52% of total biomass in the two years respectively. Collectors constituted 50 and 78% of numbers and 20 and 22% of biomass. Most populations showed consistent seasonal patterns in the two years. These appear to be due to “keyed” responses of the fauna (hatching, emergence) to predictable patterns of discharge and temperature as well as to catastrophic effects of floods. Although monthly values for richness, diversity, and equitability were similar in the two years, they varied more during year 1.

ISSN:0270-5060    

DOI:10.1080/02705060.1981.9664013

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The simultaneous effect of sex, initial size, and temperature on growth rates, adult size, and size at large wing-pad (LWP) stage ofHexagenia bilineata(Say) mayflies was investigated. We found that female nymphs grew faster than males; that growth at the constant temperature of 15°C was significantly less than at 22.5 and 30.0°C; and that smaller nymphs tended to grow faster than larger nymphs over a period of 49 days. Size of nymphs at the LWP stage was significantly related to sex, with females being considerably larger. Within the same initial size groups, all nymphs reared at 30°C were significantly smaller at the LWP stage than nymphs reared at 22.5°C and 15°C. Metamorphosis was not successful at 15°C. Adults reared at 30°C were significantly smaller than those reared at 22.5°C. The nearly synchronous emergence times of nymphs initially in the 13.5-mm and 17-mm size classes at both 22.5 and 30°C, suggested that adult tissue maturation was initiated almost simultaneously in nymphs of those two sizes. The lag in emergence of nymphs at the initial size of 9 mm suggested that a size-dependent threshold for adult tissue maturation exists between 9 and 13.5 mm body length. Finally, while 15°C was too low to permit successful emergence, it did not inhibit adult tissue maturation.

ISSN:0270-5060    

DOI:10.1080/02705060.1981.9664014

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Benthic macroinvertebrates and physicochemical parameters were monitored simnl taenously with hydrilla (Hydrilla verticillataRoyle) biomass in a Central Florida lake. Twenty-seven of the 54 taxa of benthic macroinvertebrates collected were members of the family Quronomidae. Chironomids and oligochaetes numerically dominated the benthos, comprising 82% of the individuals collected. The greatest numbers of taxa and individuals were found during the winter when hydrilla biomass was low. Hydrilla biomass ranged from 0.382 kg/m2-FW in April, 1977 to 2.275 kg/m2-FW in October, 1977. Low numbers of macroinvertebrate taxa and individuals were collected from bottom sediments during sunnier and fall. Dissolved oxygen concentrations at the bottom were approximately 2.0 ppm during summer and fall and possibly limited benthic organisms. The annual means for the Shannon and Simpson indices for the benthos were 1.92 and 0.35, respectively.

ISSN:0270-5060    

DOI:10.1080/02705060.1981.9664015

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

An enclosure-exclosure experiment was performed in Nonquit Pond, Rhode Island to test the effect of grazing byAmnicola limosa(Say) (Gastropoda) upon lentic periphyton. Periphyton from enclosures withA. limosahad higher organic content in May and July, and lower standing crops in May, July, August, and September than periphyton from exclosures withoutA. limosa.Small diatom (< 18 μm long, other thanCocconeis placentula) abundances on glass slides were significantly lower in the enclosures than in the exclosures.Cocconeisabundances were not significantly affected by grazing.Cocconeisrelative abundances on glass slides exposed in the littoral zone of Nonquit Pond also increased with increased grazing pressure fromA. limosa.Because characteristics of Nonquit Pond do not seem to be unusual, and grazer abundances were not extreme, these data may have general importance to the study of lentic periphyton community structure.

ISSN:0270-5060    

DOI:10.1080/02705060.1981.9664016

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Construction of an inexpensive stream bottom sampler, called a T-Sampler, is described. More than 6.5 T-samples can be taken and hand sorted as quickly as one Square Foot Surber sample and yield significantly more benthic organisms, especially numerically dominant taxa, than the Surber Sampler.

ISSN:0270-5060    

DOI:10.1080/02705060.1981.9664017

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Nutrient and population dynamics accompanying algae-bacteria interaction were observed in unialgal, 18-liter batch cultures during a light-dark cycle. The green algaChlorella vulgaris, and the nitrogen fixing blue-greenAnabaena flos-aquaewere inoculated with an aquatic community of bacteria. The bacteria community enhanced the regeneration of nutrients. Of special note, is the observed generation of soluble nitrogen in the synthetic growth media via nitrogen fixation followed by mineralization.

ISSN:0270-5060    

DOI:10.1080/02705060.1981.9664018

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Photosynthetic uptake of H14CO3−by phytoplankton in a small freshwater pond was measured on six different dates. Nitrate and phosphate concentrations did not limit the photosynthetic rates of these phytoplankton. Light intensity and CO2concentrations did affect photosynthesis, with dissolved CO2definitely limiting photosynthesis on two of the dates and possibly limiting it on a third date. CO2-limitation of photosynthesis occurred even in the presence of high concentrations of HCO3−(2–3 mM) on days when there was a large standing crop of actively photosynthesizing phytoplankton.

ISSN:0270-5060    

DOI:10.1080/02705060.1981.9664019

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Phytoplankton are not distributed uniformly in their aquatic habitat. Vertical and horizontal distribution patterns of phytoplankton in a temperate pond ecosystem v/ere directly affected by an extensive duckweed mat. Light, temperature, and dissolved organic matter undoubtedly were important distribution determinors; dissolved oxygen, carbon dioxide, and pH were not. This study also suggests that two little considered components of light, day-length and quality are more important in phytoplankton distribution patterns than previously thought.

ISSN:0270-5060    

DOI:10.1080/02705060.1981.9664020

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor