摘要:

AbstractExamination of sediment cores taken from shallow coastal regions of the Baltic showed that some algae were still alive at depths beyond the depth of light penetration. Their cells contained chlorophyll and photosynthesis resumed when they were exposed to light. Photosynthesis was detected by simultaneous measurement of oxygen production and14C uptake. Autoradiography was used to detect incorporated14C. The autoradiographic method was improved by a few modifications.

ISSN:0020-9309    

DOI:10.1002/iroh.19890740602

出版商:Akademie Verlag, Berlin    

年代:1989

数据来源: WILEY

摘要:

AbstractA population ofChironomus plumosus(L.) from a fish pond has been investigated for two years. Quantitative benthic samples and emergence traps were used to study the seasonal dynamics. Effect of some factors on the duration of development was studied in laboratory experiments. Data on larval abundance, length frequency analysis and emergence of adults suggest a bivoltine life cycle. The population ofC. plumosusinvestigated showed a pronounced tendency to dormancy, even under long‐day conditions. Factors regulating the bivoltine life cycle are discusse

ISSN:0020-9309    

DOI:10.1002/iroh.19890740603

出版商:Akademie Verlag, Berlin    

年代:1989

数据来源: WILEY

摘要:

AbstractExperiments involving low‐dose additions of phosphate, ammonium, nitrate and ADP, one by one and in combination, were performed in small (350 litre) in‐situ enclosures in a moderately acid (pH 5.4) lake. Before manipulation, all large filter‐feeding animals were removed by filtration. Phytoplankton responded to the nutrient additions only when both phosphorus and nitrogen were added, thus indicating a close balance between phosphorus and nitrogen limitation in the system.Variation of the inorganic nitrogen‐source resulted in species‐specific responses by phytoplankton. With ammonium as the nitrogen sourceMerismopedia tenuissimawas favoured, regardless of whether this species was dominant in the phytoplankton community at the beginning of the experiment or not. With nitrate as nitrogen sourcePeridinium inconspicuum, which was never particularly common at the beginning of the experiments, was favoured. No other species of phytoplankton present in the bags was able to outcompete these two species as long as inorganic nutrients were added. With ADP as phosphorus source together with nitrate, a third species,Dictyosphaeriumcf.botrytella, was favoured and reached dominance. The zooplankton community remaining in the bags, dominated by rotifers and calanoid nauplii, did not respond to the fertilization‐induced increases in the total biomass of ph

ISSN:0020-9309    

DOI:10.1002/iroh.19890740604

出版商:Akademie Verlag, Berlin    

年代:1989

数据来源: WILEY

摘要:

AbstractPreliminary observations were made between October 1982 and May 1983 on the nature, taxonomic composition, spatial distribution, buoyancy behaviour and nutrient requirements of some unusual planktonic algal “jellies” in Oguta Lake in Southeastern Nigeria. These “jellies” are macroscopic, blue‐green algal masses whose excessive mucilage of high consistency acts as substrata for other epiphytic components viz. diatoms and green algae. They are more abundant in the lentic areas of the lake, undergo diurnal vertical movements and have their growth enhanced by spikes of nitrogen and phosphorus salts into their aquatic medium. The effects of these “jellies” on the ecology and general water use of the lake are discussed. Speculations on the reasons for their occurrence are given and possible control meas

ISSN:0020-9309    

DOI:10.1002/iroh.19890740605

出版商:Akademie Verlag, Berlin    

年代:1989

数据来源: WILEY

摘要:

AbstractRelationship between bacteria and ciliates was investigated in continuous cultures with and without the recycling of flocculated biomass. Monocultures of ciliates of various ecological types were used together with mixed cultures of bacteria or bacteria and flagellates. The effect of ciliates on the distribution of flocculated and dispersed, biomass was tested with respect to characterizing an optimum mixed culture for activated‐sludge treatment. Monoprotozoal populations were not successful in stabilizing the morphology of a bacterial community in a system with recycling of flocculated biomass. Stabilization was observed (with particular ecological types of ciliates) in the system with a high residence time without recycling and/or in the system with the recycling inoculated by both flagellates and ciliate

ISSN:0020-9309    

DOI:10.1002/iroh.19890740606

出版商:Akademie Verlag, Berlin    

年代:1989

数据来源: WILEY

摘要:

AbstractResponses of different planktonic algae species to copper treatment were tested using semi‐continuous culture and compared with studies on copper‐induced changes in species composition of phytoplankton samples. Blue‐green algae exhibit lowerEC100‐values than diatoms andScenedesmus.The four tested strains ofMicrocystis aeruginosashowed different copper sensitivity.Four response types can be distinguished.1. rapid biomass loss after copper application but subsequent growth recovery.2. fluctuations of growth but no loss of biomass at sublethal concentrations3. continuous recovery of growth rates after initially affected growth.4. growth inhibition (dormancy) and recovery after inoculation into a copper‐free medium.Species response to copper application within a phytoplankton sample agrees with pure culture

ISSN:0020-9309    

DOI:10.1002/iroh.19890740607

出版商:Akademie Verlag, Berlin    

年代:1989

数据来源: WILEY

摘要:

AbstractDistribution of planktonic luminous bacteria in relation to environmental parameters was investigated at two stations located in the Vellar Estuary. Luminous microflora showed a pronounced seasonal cycle with very low counts during monsoon months followed by an increase in post monsoon and peak counts during summer. The population density of these procaryotes was remarkably high ranging from 3.5 to 33.1 colony forming units per ml. They constituted 2.1 to 52.1 % of the total bacterial counts. Salinity appeared to govern the distribution of luminous procaryotes as their counts corresponded well with fluctuations in salinity. Taxonomic affiliation of the isolates revealed predominance ofVibrio harveyi.Vibrio fischeriandPhotobacterium leiognathiexhibited sparse distribution.

ISSN:0020-9309    

DOI:10.1002/iroh.19890740608

出版商:Akademie Verlag, Berlin    

年代:1989

数据来源: WILEY

摘要:

AbstractCertain chemical constituents (NO3‐N, bio‐available P, Ca, Na, K, Mn, Cu, Co and organic matter) together with pH, Eh and clay content of surface sediments at various depths of the overlying water in Lake Bhim Tal were examined during 1977—1978. In addition, NH3‐N and dissolved oxygen at the mud‐water interface (water immediately above the sediments) were measured.The values of Eh, pH and NO3‐N in the sediments showed a negative relationship with water depth and positive relationship with dissolved oxygen at the interface. The other variables of the sediment were positively related to water depth and negatively related to dissolved oxygen at the interface. Organic matter, K, Na and Ca showed positive relationship with the amount of clay while the cations (K, Na, Ca) and trace metals (Cu, Mn, Co) showed a positive relationship with the amount of organic matter in th

ISSN:0020-9309    

DOI:10.1002/iroh.19890740609

出版商:Akademie Verlag, Berlin    

年代:1989

数据来源: WILEY

摘要:

AbstractEffects of piperonyl butoxide and carbaryl synergism were studied on the metabolism of the snailLymnaea acuminata. Snails were exposed to 40 % and 80 % of the 48 h LC50of carbaryl or carbaryl + piperonyl butoxide mixture (1:5). The amount of carbaryl present in the LC50mixture was only 0.23 % of the LC50of carbaryl alone. The treatments caused a dose‐dependent decrease in glycogen and protein levels and acetylcholinesterase (AChE) and alkaline phosphatase activity; simultaneously, there was an increase in levels of lactic acid, reducing sugars and amino acid and the activity of acid phosphatase. Significant differences in AChE and phosphatase activity were also observed between the effects of equivalent concentrations of carbaryl and carbaryl‐synerg

ISSN:0020-9309    

DOI:10.1002/iroh.19890740610

出版商:Akademie Verlag, Berlin    

年代:1989

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19890740612

出版商:Akademie Verlag, Berlin    

年代:1989

数据来源: WILEY