ISSN:0270-5060    

DOI:10.1080/02705060.1982.9664051

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Polar ordination of fish capture data from Nine Mile Creek, Onondaga County, New York, indicated the presence of localized midsummer assemblages of fishes that corresponded to pool, riffle, and intermediate transition habitats (pool head, pool tail, run). The white sucker was characteristic of pools; longnose and blacknose dace predominated in riffles. The cutlips minnow, creek chub, northern hog sucker, and tessellated darter used transition habitats extensively. Species diversity was high in the pool, pool head, and run, and low in the riffle and pool tail; differences among habitats were due to variation in both species richness and species evenness.

ISSN:0270-5060    

DOI:10.1080/02705060.1982.9664052

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Hybrid grass carp, spawned at the Malone Fish Hatchery in 1979, were stocked into two Central Florida lakes containing hydrilla (Blue Lake) and coontail (Crealde Lake) at the rate of 183 fish ha−1after nearly two years vegetation control was not achieved. A 24% reduction in the number of hybrid grass carp occurred in Blue Lake while an 89% reduction occurred in Crealde Lake. Hybrid grass carp in the coontail lake had a growth rate of 1.3 gm mo−1while the growth rate in the hydrilla lake was 28 gm mo−1. A total of 49% of the fish in the hydrilla lake was less than 450 gn after 20 mo. Feeding trials in 0.14 ha experimental ponds using triploid hybrid grass carp from Blue Lake revealed that 0.8 kg hybrid grass carp had a feeding rate of approximately one-third less than that of similar sized grass carp and had a growth rate of approximately seven times less. The feeding efficiency of two year old hybrid grass carp was nearly 50% less than for one and one-half year old grass carp. Due to the slower growth, lower feeding rate, and high mortality of hybrid grass carp, the ability of the hybrid grass carp to be used as a low cost, effective weed control agent is doubtful since a longer grow out period to achieve a suitable stocking size and a much larger number of fish will be required.

ISSN:0270-5060    

DOI:10.1080/02705060.1982.9664053

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Longnose dace and blacknose dace were collected from the Waccabuc River in Westchester County, N.Y. Stomach content analysis revealed that the diets of the two species were similar and dominated by hydropsychid larvae. Overlap calculations showed there was greater similarity in diet between the two species where they were found together than between different collections of the same species, indicating that diet was more a function of when and/or where specimens were collected than of species identity.

ISSN:0270-5060    

DOI:10.1080/02705060.1982.9664054

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Daphnia pulex, a common cladoceran zooplankton species, contains tissue cAMP concentrations similar to those found in algae, bacteria, and aquatic macrophytes.Daphniarelease significant quantities of cAMP into the extracellular medium. Release of algal cellular cAMP as a result of digestive degradation of algal cells may also be an important source of dissolved cAMP in lake-water.

ISSN:0270-5060    

DOI:10.1080/02705060.1982.9664055

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Variations of neuston adenosine triphosphate (ATP) over a 24 hr period confirmed observations of nocturnal surface film formation. ATP concentrations ranged from a low of 0.4 pmol.cm−2at 1200 hrs to 7.4 pmol. cm−2at 2000 hrs. The ATP dynamics were only partially explained by phytoplankton accumulation.Peridinium, which accounted for most of the phytoplankton volume at 2000 hrs, was related to the formation of the film, but did not account for the duration of the film. The physical parameters, wind speed, solar radiation, and water surface temperature, were negatively correlated with ATP. A causal relationship between any one variable and neuston biomass as represented by ATP could not be demonstrated. The processes, diel convective mixing and phytoplankton migration, may both contribute to the formation of the surface film in Lake Louise.

ISSN:0270-5060    

DOI:10.1080/02705060.1982.9664056

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Zooplankton and macroinvertebrate drift was sampled in the Barren River Lake tailwater in July 1980 and January 1981 at two stations, 0.4 and 23 km downstream from the dam, to determine variations in diurnal, seasonal, and spatial abundance. Zooplankton, largely from the reservoir, was densest near the reservoir outflow and was reduced downstream. Some diurnal variation in abundance was noted in January but not in July. Zooplankton was about fivefold more abundant in the tailwater in January than in July; this difference was related to reservoir stratification and vertical movement of these organisms in the reservoir. During both sampling periods, macroinvertebrate drift in the immediate tailwater was dominated by Chaoboridae, which were exported from the reservoir during the night. At the downstream station, macro-invertebrates were less influenced by the reservoir, and the nocturnal increase in densities and taxa was more typical of the drift in a natural stream. Macroinvertebrates were several times more abundant in July than in January.

ISSN:0270-5060    

DOI:10.1080/02705060.1982.9664057

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Net plankton community structure and numbers were studied in soft-water, acidic ponds containing aquatic macrophytes, after introduction of the herbivorous grass carp (Ctenopharyngodon idella). The plankton communities in ponds with grass carp consisted of significantly fewer individuals, genera, and orders than did the communities in control ponds. Expected shifts from desirable to undesirable species of plankton did not occur. These results demonstrate that plankton blooms are not an inevitable result of stocking grass carp, and support the suggestion that macrophytes may be especially significant in nutrient cycling in soft-water, acidic systems.

ISSN:0270-5060    

DOI:10.1080/02705060.1982.9664058

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The bacteriological impact of clamshell dredging Mississippi River bottom sediment (river mile 820 [about 1,320 km]) was investigated. Total coliform (TC), fecal coliform (FC), and fecal streptococcus (FS) densities were determined for dredged sediment and for water samples collected from above and below the clamshell dredge and above and below discharge of dredged material. Each sample was also examined for the presence of salmonella and shigella. Results indicated that clamshell dredging had no significant effect (at the level α = 0.05) on microbiological water quality as measured by TC, FC, FS, and FC/FS determinations. Salmonellae were detected in 7.1% of the upstream samples and in 16.7% of the downstream samples.

ISSN:0270-5060    

DOI:10.1080/02705060.1982.9664059

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

A biotic analysis of lotic environments was designed, using ecological tolerances and requirements of the numerically dominant macrobenthic invertebrates. This method, “Ecological Community Analysis” (ECA), uses the habitat, habits, mode of feeding, temperature preference and silt- and hypoxia-tolerances of the dominant organisms to isolate the most important environmental factors associated with biotic communities.

ISSN:0270-5060    

DOI:10.1080/02705060.1982.9664060

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor