摘要:

During 1981 the seasonal growth and community composition of phytoplankton were investigated at six sampling stations in Eau Galle reservoir, a shallow eutrophic basin located in central Wisconsin, U.S.A. Eau Galle was strongly dominated by diatoms (spring and fall), and co-dominated by cyanophytes and dinoflagellates (summer). Three species (Stephanodiscus hantzschiiGrun.,Aphanizomenon flos- aquae(L.) Ralfs, andCeratium hirundinella(O.F.M.) Schrank) collectively contributed about 50% of total annual phytoplankton biomass. Phytoplankton response was quite similar at open water sampling stations, but differed at a station in the littoral zone and at another located near the mouth of the primary inflowing river. Depressed epilimnetic silica concentrations occurred during spring and fall periods of diatom growth. The development of nitrogen-fixing cyanophyte populations during the summer reflected reduced dissolved inorganic nitrogen availability. Midsummer mixing events reduced water column stability. Shifts in the phytoplankton species composition of Eau Galle appeared to occur in response to major changes in water column stability.

ISSN:0270-5060    

DOI:10.1080/02705060.1984.9664634

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

A method to obtain accurate dissolved oxygen concentration (DO) measurements within a 16-mm microzone was developed using oxygen-permeable dialysis tubing with a 12-ml water sample and a modification of the micro-Winkler technique. Controlled experiments showed that W within tubes reached 99% equilibrium with ambient water in less than 3 hours in lotic waters and in less than 5 hours in lentic waters with experimental error of 0.05 mg/liter. A kit to perform the DO measures can be assembled for about $150, and samples can be run in less than 10 minutes.

ISSN:0270-5060    

DOI:10.1080/02705060.1984.9664635

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Dissolved phosphorus fractions present in the surface waters of a eutrophic reservoir lake in northcentral Oklahoma were characterized by chemical, enzymatic, and chromatographic techniques. Simultaneous measurements of alkaline phosphatase activity (APA) were also conducted on each lakewater sample. An inverse biphasic linear relationship was found between soluble reactive phosphorus concentrations (SRP) and APA on a seasonal basis. Phosphomonoesters (PME) comprised from 0–65 percent of the soluble unreactive phosphorus (SUP) pool and an inverse linear relationship was found between PME concentrations and APA on a seasonal basis. Gel filtration chromatography of filtered lake water from the above system and a mesotrophic lake exhibiting high clay turbidity supported the view that the majority of complex phosphorus in these systems existed as low molecular weight phosphate esters.

ISSN:0270-5060    

DOI:10.1080/02705060.1984.9664636

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The reproduction and early growth of the erpobdellid leechNephelopsis obscurain laboratory culture are presented, enabling a comparison to size structure of natural populations. IndividualNephelopsis obscurain culture were found to produce cocoons over a prolonged spawning period with emergent young of markedly different weight. These characteristics along with differential growth of the young result in a highly skewed weight distribution of a generation of leeches. The extreme weight range in a cohort ofN. obscurapresents difficulties in aging erpobdellids.

ISSN:0270-5060    

DOI:10.1080/02705060.1984.9664637

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

In preliminary laboratory studies, the endangered musselLampsitis higginsiwas unable to burrow into rocky substrates, but did burrow into substrates comprised of silt, clay, sand, and/or pebble-gravel. Burrowing times were shortest in silt and longest in pebble-gravel. As judged by longevity of glochidial infection, walleye (Stizostedion vitreum) and largemouth bass (Micropterus satrnoides) may be suitable hosts for the parasitic stage. When glochidia were placed in water without host fish, half had died after 48 hours, and all had died after 72 hours.

ISSN:0270-5060    

DOI:10.1080/02705060.1984.9664638

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

A field survey was conducted principally during the summers of 1980 through 1982 in all 39 counties and both physiographic provinces of middle Tennessee. Eight species of planarians, representing four families, were found in 26 counties and at 124 sites: 60 in the Central Basin province and 64 in the Highland Rim province.Dugesia tigrinaoccurred at more sites (31) than any other species and was most often in the Central Basin.Dugesia dorotocephalaandCurs foremaniiwere found in 26 and 19 sites, respectively, and were about equally distributed between the two provinces.Phagocata gracilisoccurred at 18 sites, and more of these sites (16) were in the Highland Rim. Of 16 sites forPhaocata morgani, one-half were springs located mostly in the Highland Rim.Phagocata velataoccupied 10 sites, all in the Central Basin. New records forProcotyla fluviatiliswere established at two sites in the Highland Rim.Sphalloplana chandleri, a cave planarian, occurred at two sites, one in each province. Triclads were abundant (50–100 in 20 min. or less) or very abundant (>100) at seven sites: one site each forD. dorotocephalaandD. tigrina, and two sites forPh. gracilis, all in the Highland Rim; and, one site each forD. dorotocephala, D. tigrina, andPh. velata, all in the Central Basin. Data on water temperature, calcium, pH, and substrate are included.

ISSN:0270-5060    

DOI:10.1080/02705060.1984.9664639

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The effluent stream of the Cardinal Plant coal fly ash pond in eastern Ohio was characterized by less diverse habitat and food resources and a less complex substratum compared with an adjoining stream unaffected by the effluent, and supported a less diverse macroinvertebrate fauna dominated by physicochemically tolerant, fine particle-consumers. A sampling site in the unaffected stream contained large numbers of shredders and generally exhibited greater macroinvertebrate abundance than two sites in the effluent.

ISSN:0270-5060    

DOI:10.1080/02705060.1984.9664640

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The diets of the poorly described early life history stage of redbreast sunfish and northern redbelly dace were examined when the species coexisted in the littoral zone of an Adirondack Lake. The prey of redbreast sunfish fry included cladocerans, copepods and amphi-pods, all associated with a mid-water feeding station. The diet of northern redbelly dace fry was dominated by emergent chironomids and terrestrial insects which suggests surface feeding. Diet overlap was very low since the two species were apparently utilizing different food organisms in separate regions of the water column.

ISSN:0270-5060    

DOI:10.1080/02705060.1984.9664641

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Four distinct types of cool-water areas were located during this midsummer survey of Thrash Creek, Washington, a warm, fifth-order stream. These areas were termed lateral seeps, pool bottom seeps, cold tributary mouths and flow through the bed, depending upon the entry point and source of the cool water. These types differed with respect to average size, depth and location in the stream channel. Temperatures in the cool water areas averaged 4.7°C lower than ambient streamwater on warm afternoons. Thirty-nine such spots were found on a 3.5 km reach of the study stream. They accounted for 1.6% of the surface area and 2.9% of the water volume on this stretch of stream.

ISSN:0270-5060    

DOI:10.1080/02705060.1984.9664642

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Three methods of sampling fishes, two seining methods and a drop trap method, were evaluated in heavily vegetated freshwater habitats. The portable drop trap method, which utilized a 1 × 1 m-sq. trap, collected significantly more macroinvertebrates and fish per unit area than did the seining methods. The meter square drop trap offered the additional advantages of a greater number of animals per unit effort and an integrated sample of vegetation, macroinvertebrates and fish in a given area. A 90% (s.d.= 7.4%) recovery of tagged fishes released into the traps in different habitats showed the m2drop trap to be a highly reliable and effective sampling method for fish in vegetated wetlands.

ISSN:0270-5060    

DOI:10.1080/02705060.1984.9664643

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor