摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f74-044

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Primary production values in Lake Ontario were low in winter, reached a maximum in midspring, declined during summer, and slightly increased in fall. Rate of increase of production for inshore waters (< 20 m depth) was greater especially in spring and early summer with a greater maximum reached earlier than in offshore waters. Assimilation numbers, mgC fixed/mg chlorophyllaper hour, in Lake Ontario were fairly constant over the lake with a yearly range of 1.2–1.6. Primary production showed a linear relationship to chlorophyllaconcentration, as also occurred in Lake Erie.Lake Erie primary production varied in its three basins. Seasonally, in the Eastern Basin, production was highest in spring with a midsummer decline, and small peaks in fall. The Western Basin had a maximum in midsummer whereas the Central Basin had peaks in late summer and early fall. Assimilation numbers were highest in the Western Basin (up to 3.5 mgC/mg chlorophyllaper hour) and lowest in the mid-Central Basin and Eastern Basin with values of approximately 1.4 mgC/mg chlorophyllaper hour. A definite westerly increase of assimilation number was observed.Up to early summer, the two lakes were fairly equal in surface production but integral photosynthesis, mgC/m2per hour was higher in Lake Ontario than in Lake Erie. The same was valid in November and December. In summer, Lake Erie was higher in production on both a mgC/m3per hour and mgC/m2per hour basis. For the period, April–December, Lake Ontario's total estimated yield was 170 gC/m2, whereas for Lake Erie values of 160, 210, and 310 gC/m2were found for the Eastern, Central, and Western basins, respectively.

ISSN:0706-652X    

DOI:10.1139/f74-045

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Chlorophyllaanalyses including pheopigments were made on water samples taken on 10 cruises on Lake Erie between April and December, 1970. The highest mean chlorophyllavalues of approximately 11 μg/liter occurred in the mid-Western Basin, with a second maximum of 6 μg/liter off Erie, Pennsylvania. The southern shore is also characterized by high values of chlorophyll to the east of Cleveland, Ohio. The lowest yearly means were found in the eastern portion of the Central Basin and most of the Eastern Basin (approximately 3 μg/liter.) Ratios of chlorophyllabetween the Eastern, Central, and Western basins have a yearly mean of 1:1.4:2.8, respectively; with maximum differences in the summer, i.e. late August, the ratio was 1:1.5:7.2.Pheopigment concentration in the surface waters reached a maximum in late October corresponding to the fall overturn of the lake and subsequent resuspension of organic matter containing degradation products from the bottom of the lake. No significant correlation was found between zooplankton abundance and pheopigment concentration as in other water bodies studied. This may indicate that zooplankton food chains are primarily detrital in Lake Erie, with grazing of living phytoplankton playing a lesser role compared with more oligotrophic water bodies.

ISSN:0706-652X    

DOI:10.1139/f74-046

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

During 1970, temperature and nutrient distributions were measured in surface waters of lakes Ontario (12 cruises) and Erie (10 cruises). Nutrient patterns are compared and discussed in relation to temperature, primary production, and nutrient sources.In Lake Erie, due to the early onset of the phytoplankton spring bloom, nutrient concentration started to decrease much earlier than in Lake Ontario. During spring, patterns of nutrients, chlorophylla, and primary production were influenced by the thermal bar in Lake Ontario. In Lake Erie the nutrient supply controlled such patterns. In Lake Erie inorganic nutrients were depleted lake-wide in summer; in Lake Ontario, nutrients were highest in regions where upwelling occurred or inputs were high. Due to the earlier onset of fall overturn in Lake Erie, the nutrient concentration started to increase earlier in the fall than in Lake Ontario.

ISSN:0706-652X    

DOI:10.1139/f74-047

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Depth profiles of calm water settling velocities were measured in situ using specially constructed sampling bottles. Samples of water were taken at specific depths and the settling process commenced as soon as the samples were taken. Just before retrieval of the bottles, the samples were subdivided into upper and lower portions so that settling velocities could be calculated; these varied between − 0.4 and + 2.0 m day−1. Net settling velocities measured at the top of the thermocline were used to estimate net settling fluxes from the epilimnion; these varied between − 0.074 and + 0.336 mmoles of phosphorus m−2day−1. Net settling flux can differ from sedimentation flux out of the epilimnion and the necessity for a clear distinction between these two values is emphasized.

ISSN:0706-652X    

DOI:10.1139/f74-048

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

In August 1972 divers collected cores from the Central and Western basins of Lake Erie for microbiological analysis. The cores were sectioned and examined for sulfur cycle bacteria, nitrogen cycle bacteria, total heterotrophs, iron oxidizing bacteria, insoluble organic and inorganic phosphate solubilizing bacteria. Eh, nitrogen, organic carbon, and percentage moisture determinations were also made.Data from these cores indicate that offshore sediments, not directly influenced by land inputs, contain similar, homogenously distributed bacterial populations which vary less than one order of magnitude between the sediment surface and the 5-cm level.

ISSN:0706-652X    

DOI:10.1139/f74-049

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Crustacean zooplankton concentrations (numbers per m3) in the upper 50 m found in lakewide cruises during all or most of the seasons on lakes Ontario and Erie in 1970 and on Lake Huron in 1971 showed that the species of zooplankton crustaceans present in the three lakes were generally identical, although the times of maxima and relative species compositions differed. Calanoid copepods were most abundant and diverse in Lake Huron and western Lake Erie. Cyclopoids and cladocerans were most abundant in lakes Erie and Ontario and in the Saginaw Bay region of Lake Huron. The most abundant cyclopoid throughout the year in all three lakes wasDiacyclops bicuspidatus thomasi;Tropocyclops prasinusandAcanthocyclops vernaliswere abundant especially in lakes Ontario and Erie, respectively. Cladocerans were most numerous in lakes Erie and Ontario. Numbers of individuals fluctuated markedly through the season with maxima in the spring or summer months in all three lakes.Biomass values (ash-free dry weight) were highest in Lake Erie, especially the Western Basin, and in Saginaw Bay of Lake Huron. Although numbers of crustaceans/m3were much lower in Lake Huron than in Lake Ontario, net biomass values were similar. This was due to the greater size and average weight of crustaceans in Lake Huron samples. Inshore waters of lakes Ontario and Huron and all three basins of Lake Erie were subject to greater fluctuations in concentrations of crustacean zooplankton and net biomass values than in the pelagic waters of lakes Ontario and Huron.

ISSN:0706-652X    

DOI:10.1139/f74-050

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

In sampling on lakes Ontario, Erie, and Superior during three cruises from spring to fall, and on Lake Huron during eight cruises,Mysis relictawas generally not taken or not abundant in waters less than 25 m in depth. Its abundance appeared to increase with depth at least up to 200 m. Populations appeared to be concentrated in waters 125–200 m deep during summer and more dispersed during spring and fall. Highest numbers were found in Lake Superior, followed by lakes Ontario and Huron. A small localized population was found in the deep eastern part of Lake Erie.Size-frequency distributions from the various cruises on lakes Superior, Huron, and Ontario indicated differences in life cycles of the mysid in the three lakes. In Lake Superior there was one major period of recruitment, from February to July, and the generation time appeared to be 2 yr. In lakes Huron and Ontario recruitment appeared to occur from February to August and to be separated into a winter and a summer period; each of the generations appeared to mature in 18 mo.

ISSN:0706-652X    

DOI:10.1139/f74-051

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

A method for studying plankton biomass by comparing the results between planktonnet hauls and an integrated water column sample is described. Filtering the planktonnet sample through glass-fiber filter papers would yield planktonnet phytoplankton plus zooplankton biomass. Filtering the integrator sample would yield total phytoplankton biomass. Sieving part of this sample would give direct estimates of net and nannophytoplankton which could be used in combination with the values of net plankton biomass to give estimates of total biomass and zooplankton biomass.Ash-free dry weight is recommended instead of dry weight biomass. The results are easy to produce, are comparable with other parameters such as particulate carbon and nitrogen, and are in units which may be used in the determination of trophic status or nutrient budgets for a lake.

ISSN:0706-652X    

DOI:10.1139/f74-052

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The calculated flux of carbon dioxide between Lake Ontario and the atmosphere ranged from about 0.1 gC m−2day−1during the summer to about 3 during a winter storm. During the summer, the amount of carbon supplied from the atmosphere was from 5 to 30% of the estimated amount utilized in primary production. Also Lyman's dissociation constants for carbonic acid were found applicable to the carbonate system of the lake.

ISSN:0706-652X    

DOI:10.1139/f74-053

出版商:NRC Research Press    

年代:1974

数据来源: NRC