摘要:

AbstractChydorus biovatusdiffers fromC. sphaericussens. str. in that the ephippial female carries two resting eggs, for which the brood pouch is expanded dorsally. resulting in a sharp angle in lateral contour near the junction of the head and shell and in the postpore distance being much elongated. The mature male has the pre‐anal angle of the postabdomen rounded and the rostrum broadly rounded, both features being much different than inC. sphaericussens. str. In North America there is a progressive replacement ofC. brevilabris‐group species in the South toC. sphaericus‐group species in the Far North. Production of two resting eggs byChydorus pigeris rec

ISSN:0020-9309    

DOI:10.1002/iroh.19850700102

出版商:Akademie Verlag, Berlin    

年代:1985

数据来源: WILEY

摘要:

AbstractThe seasonal and vertical distributions ofAcanthostomella norvegicaare described from two fjord‐like bays in insular Newfoundland, Canada. Resting spores are figured and describe

ISSN:0020-9309    

DOI:10.1002/iroh.19850700103

出版商:Akademie Verlag, Berlin    

年代:1985

数据来源: WILEY

摘要:

AbstractThe data for solar radiation (S), air temperature (Ta), surface water temperature (Tw) and pH recorded at 0.5 hr intervals at Slapy Reservoir were subject to spectral analysis. The complete series covered the month of July 1978, where three characteristic sections were distinguished, of which one was characterized by low variations, more irregular values and a slowly decreasing trend and another with high and regular variations as well as a steeply increasing trend. These sections were analysed separately in addition to the complete series. The period of 24 hrs was most important and represented forS,Taand pH 60, 38 and 18 % of the total variances, respectively. The deterministic periodic component represented 65–95 % of the total variance. The cross‐correlation and cross‐covariance between selected pairs of variables suggested lags of up to 4.5 hrs, the longest lag being observed forTwandS. An autoregressive model of the interrelation between the signals was formu

ISSN:0020-9309    

DOI:10.1002/iroh.19850700104

出版商:Akademie Verlag, Berlin    

年代:1985

数据来源: WILEY

摘要:

AbstractIn this contribution, different possibilities for designing and operating microcosms have been reviewed. Examples of geometrical and of physiological similarity between systems of different sizes and the corresponding scaling functions have been considered. The simulation of the community metabolism (% BOD removal) of waste treatment lagoons by means of microcosms and the selection of proper similarity criteria yielded results which reasonably corresponded to the data directly measured in existing full‐scale ponds and dealt with in the literature. The change in phytoplankton primary productivity per unit volume of the epilimnion with change in mean depth of a variety of lakes to be expected from dimensional analysis was found to be in good agreement with empirical data recorded in the literatur

ISSN:0020-9309    

DOI:10.1002/iroh.19850700105

出版商:Akademie Verlag, Berlin    

年代:1985

数据来源: WILEY

摘要:

AbstractThe trophic status of Lake Maggiore is revised following the OECD (1982) approach to eutrophication, using detailed, long‐term data on nutrient sources and loads, and in‐lake nutrient, chlorophyll and phytoplankton conditions as a factual basis. Alternative hypotheses of phosphorus load reduction are considered in the light of partial measures already under way. The need for an integrated, whole‐basin restoration strategy is empha

ISSN:0020-9309    

DOI:10.1002/iroh.19850700106

出版商:Akademie Verlag, Berlin    

年代:1985

数据来源: WILEY

摘要:

AbstractAn indispensable dependence on selenium (Se) was established for the dinoflagellatePeridinopsis Borgei(Lemm.) Lemm. The alga regularly blooms in semi‐meromictic lakes close to the Baltic Sea. A vitamin B12requirement is indicated for the alga as well as increased levels of micronutrients. A culture medium specifically designed forP. Borgeiis presente

ISSN:0020-9309    

DOI:10.1002/iroh.19850700107

出版商:Akademie Verlag, Berlin    

年代:1985

数据来源: WILEY

摘要:

AbstractA primary blastodise develops 2 hours and 40 minutes after artifical fertilization at 8 0/00 C and 15 0/100 S. The egg then begins embryonic development. When incubated in water with the oxygen concentration reduced to 50 % or 15 % saturation, the oxygen consumption of the eggs decreased to 73 % or 41 % of normal, respectively. For thein situexperiments, eggs and sperm taken from living fishes were spread on plexiglas plates in a way that monolayers adhered to the surface. The plates were then moored to buoys at two depths in a spawning area at Pötenitzer Wiek near Travemünde. Egg mortality increased with the duration of incubation. About 90 % of the spring spawn died before hatching, but only a 10 % mortality occurred among those spawned in autumn. Scanning electron microscope examination revealed structural changes on the egg surfaces caused by bacteria and particles of sediment. The role for survival of the pattern formed by the eggs as they adhere to the surface is discusse

ISSN:0020-9309    

DOI:10.1002/iroh.19850700108

出版商:Akademie Verlag, Berlin    

年代:1985

数据来源: WILEY

摘要:

AbstractThe total phosphate content of the water in a well delimited region of the Wadden Sea (26.8 km2) was determined by multiplying the concentration by the water volume during each phase of the tide. When the weather is moderate, sharp but stable gradients are observed from the shore to the open sea resulting from the remineralization processes that occur most rapidly near the shore.

ISSN:0020-9309    

DOI:10.1002/iroh.19850700109

出版商:Akademie Verlag, Berlin    

年代:1985

数据来源: WILEY

摘要:

AbstractKinetics of uptake, partitioning and elimination of cadmium were investigated in experimental studies with the freshwater mussel,Dreissena polymorpha. The radioactive cadmium isotopes109Cd and115Cd were used as tracers. Shells, soft parts and body fluid of the mussel exhibited considerable differences in accumulation and elimination. Accumulation factors up to more than 70,000 were calculated for the periostracum, whereas accumulation factors for the whole mussels ranging up to 3,000 were calculated. The shells bound a great deal of cadmium, but only loosely, and the metal could be readily eliminated after transfer to uncontaminated water. In contrast, no significant amounts of the cadmium incorporated in the soft parts were eliminated. The results indicate that the major portion of cadmium in the soft parts is strongly bound and cannot be eliminated by exchange processes.

ISSN:0020-9309    

DOI:10.1002/iroh.19850700110

出版商:Akademie Verlag, Berlin    

年代:1985

数据来源: WILEY

摘要:

AbstractSeries of aerial photographs taken with an interval of 6 Minutes were used to study the dynamics of the suspended matter distribution in a 1 km section of the Elbe Estuary. The observations show heterogeneous distribution patterns which are different at each phase of the tidal cycle. The comparison with the bathymetry indicates that the distribution is mainly a function of the river bed topography, which modifies the local current structure. The surface distribution in the fairway region is especially determined by the ship traffic.

ISSN:0020-9309    

DOI:10.1002/iroh.19850700111

出版商:Akademie Verlag, Berlin    

年代:1985

数据来源: WILEY