摘要:

AbstractRiver inputs of dissolved silica into a shallow eutrophic lake (Lough Neagh, N Ireland) are quantified. Exports of silica are high (3.6 to 9.6 tonnes dissolved SiO2km−2y−1), but the spring concentration of dissolved silica in the lake depends on release of silica from the sediments. Two planktonic diatomsMelosira italica subarcticaO. MÜLL, andStephanodiscus astraea(EHR.) GRUN. dominate the spring flora. Their periodicity is described over ten years and their usage of silica and phosphorus is examined. Data are presented on the resuspension of cells from the sediment, the growth rates of the diatoms in the lake, the incidence of parasites and changes in the filament length ofM. italica subarc

ISSN:0020-9309    

DOI:10.1002/iroh.19810660502

出版商:Akademie Verlag, Berlin    

年代:1981

数据来源: WILEY

摘要:

AbstractThe limnological characteristics of meromictic Hemlock Lake, Michigan, are outlined. The changes brought about by artificial destratification, and those accompanying re‐establishment of meromixis, are then described. A mechanism for the return of meromixis is suggested, and its events compared with an analogous case in a Tasmanian reservoi

ISSN:0020-9309    

DOI:10.1002/iroh.19810660503

出版商:Akademie Verlag, Berlin    

年代:1981

数据来源: WILEY

摘要:

AbstractA community of organisms dominated by gnathostomulids has been discovered at the East Flower Garden Brine Seep. This discovery clearly demonstrates that specialized communities of micro‐metazoans exist in and below sulfide‐dependent chemoclines. The term thiobios should be retained to describe these communit

ISSN:0020-9309    

DOI:10.1002/iroh.19810660504

出版商:Akademie Verlag, Berlin    

年代:1981

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19810660505

出版商:Akademie Verlag, Berlin    

年代:1981

数据来源: WILEY

摘要:

AbstractThe irradiance reachingNitellaat 11.5 m depths was almost the same during three years: 1000 cal cm−2year−1PAR, or 2.2% of the surface irradiance PAR. Green light (500–600 nm) constituted most (62–88%) of the irradiance onNitella.Net photosynthesis byNitellawas linearly correlated to irradiance.Nitellahad a positive oxygen balance from mid‐May to late September and a minor negative one at other times. The annual turnover of biomass was potentially high, and the dark‐respiration was very important in the metabolic balance. The contribution ofNitellato total autotrophic production and to oxygen conditions in the hypolimnion i

ISSN:0020-9309    

DOI:10.1002/iroh.19810660506

出版商:Akademie Verlag, Berlin    

年代:1981

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19810660508

出版商:Akademie Verlag, Berlin    

年代:1981

数据来源: WILEY

摘要:

AbstractThe purpose of the study was to compare the primary plankton productivities of lakes of different salinities and to determine the causative factors involved in their production rates. Four lakes (specific conductivity —mS cm−1at 18°C) were initially chosen: Coragulac (9), Red Rock (25), Corangamite (38), Pink (250). Sampling and production measurements were made every two to three weeks.Three lakes were dominated by specific phytoplankton blooms: Red Rock (Anabaena spiroides), Corangamite (Nodularia spumigena). Pink (Dunaliella salina). Coragulac Lake had more diverse populations.Red Rock Tarn had some of the highest production values ever recorded. Extremely high soluble phosphate and inorganic carbon concentrations were the most important causative factors. Pink Lake had very low production rates. High salinity and low nutrient concentrations were limiting factors. The other lakes were intermediate in production and nutrient levels.Zooplankton populations were also determ

ISSN:0020-9309    

DOI:10.1002/iroh.19810660509

出版商:Akademie Verlag, Berlin    

年代:1981

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19810660511

出版商:Akademie Verlag, Berlin    

年代:1981

数据来源: WILEY

摘要:

AbstractThe densities of phytoplankton and zooplankton were determined for 12 consecutive months (1978–1979) in two deep oligotrophic lakes in northern Canada. The lakes were situated on the same river system, about 5 km from one another. While they exhibited similar temperature conditions, there were slight differences in the ionic content of the water. Overall, changing temperature was the most important factor influencing the duration of the growth cycles of phytoplankton and zooplankton. Nutrients generally controlled the intensity but not the timing of algal blooms. A similar relationship was recorded for the effects of food supply on the development of the major species of herbivorous zooplankton. Although changing photoperiod likely initiated the growth of several important algal and zooplankton species in the spring and early summer, light had no measurable impact on the development of planktonic communities throughout the remainder of the growing season. The higher ionic content of the water in one lake may have promoted the growth of protozoans during the fall and early winte

ISSN:0020-9309    

DOI:10.1002/iroh.19810660512

出版商:Akademie Verlag, Berlin    

年代:1981

数据来源: WILEY

摘要:

AbstractA pure culture strain ofCyclotella meneghiniana(KÜTZ.) isolated from the hypereutrophic Bautzen reservoir (March 1980) developed from the typicalCyclotella‐shape to cells with an extremely prolonged pervalvar axis and a small diameter after five months growing under pure culture conditions. This change is interpreted as a consequence of the complete absence of grazing pressure as a selection factor. Since the cell surface/volume ratio showed a singificant increase (3.0) in comparison with the natural population (1.8), it is assumed that the culture strain has also changed with respect to physiological criteria. The conclusion is drawn that investigations of pure cultures for ecological purposes should be restricted to freshly isolated strai

ISSN:0020-9309    

DOI:10.1002/iroh.19810660513

出版商:Akademie Verlag, Berlin    

年代:1981

数据来源: WILEY