摘要:

AbstractLakes Sorell and Crescent are closely adjacent shallow lakes on the Tasmanian Central Plateau. They have similar morphometry and similar climate, geology, soils and vegetation in their catchments. They are polymictic, oxygen‐saturated and colourless but turbid. They have soft water with major ions Na, Ca, Mg, Cl, HCO3present in almost equi‐ionic quantities, and a slightly alkaline reaction. Chemically they are alike, the major difference being a 20% higher salinity in Crescent from 1967–69. During 1969–71 heavy rains reduced this difference. Water frequently flows from Sorell to Crescent in any year.Despite these similarities their phytoplankton populations differ markedly in every respect—species composition, population structure, population stability and total biomass. Lake Crescent has a standing crop 10 X that of Sorell. The former is eutrophic, the latter mesotrophic. Well marked seasonal cycles do not occur but sporadic fluctuations of biomass are brought about by hydrologic or other events.The pronounced differences in every aspect of plankton populations in two so similar and connected lakes cannot yet be explained. They remain a limnologica

ISSN:0020-9309    

DOI:10.1002/iroh.19730580303

出版商:Akademie Verlag, Berlin    

年代:1973

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19730580304

出版商:Akademie Verlag, Berlin    

年代:1973

数据来源: WILEY

摘要:

AbstractThe rates of total oxygen uptake, residual oxygen consumption after poisoning with formaldehyde, and respiration of undisturbed sediment cores from the continental terrace, the abyssal plains, and Aleutian Trench of the North Pacific were measured aboard ship. These measurements, together with determinations of organic carbon, sand, silt, and clay content, of concentrations of reduced substances, and of dissolved oxygen and nutrient salts in interstitial and overlying bottom water, give indications of the level of community metabolism, both aerobic and anaerobic, in the different study areas.

ISSN:0020-9309    

DOI:10.1002/iroh.19730580305

出版商:Akademie Verlag, Berlin    

年代:1973

数据来源: WILEY

摘要:

AbstractThis study provides the first evaluation of abundance and diversity of polychaete annelid assemblages of coral reefs. Quantitative analyses of the polychaete fauna of truncated coral reef limestone platforms off Sumatra and Thailand revealed a total of 76 species (13 reported for the first time from the tropical Indian Ocean) and average population densities of 49,000/m2. The number of species in a single sample ranged from 16 to 32, and species diversity (H) ranged from 1.9 to 2.5. Three species of Syllidae,Palola siciliensis, andDodecaceria laddioccurred in all samples. The syllids dominated numerically in all samples but were quite small, mainly 2–10 mm long and 0.01–0.04 mg dry weight. Samples from the same station were essentially identical in species composition and relative abundance. Similarity decreased with increasing distance between stations. With respect to number of species, population density, and dominance of syllids, the assemblages studied resemble those associated with limestone substrates in marine caves in the Mediterran

ISSN:0020-9309    

DOI:10.1002/iroh.19730580306

出版商:Akademie Verlag, Berlin    

年代:1973

数据来源: WILEY

摘要:

AbstractThe growth of the diatomSkeletonema costatumin culture media, with different nutrients concentrations, is followed by measuring and comparing the cell density and the nitrogen, proteins, carbon, carbohydrates, chlorophyllaand ATP contents. The experiments are carried out in order to decide the best enrichments which have to be used for the measurement of growth‐potential of sea water, withS. costatumas a test organism.The cell density appears to be ruled by very low concentrations of phosphorus, silicates, vitamin B12and also by nitrogen, but with less importance. With iron and chelator EDTA the answers are not easy to understand (because of the role of EDTA to get metal available). Inhibition appears with the highest concentrations.In phosphorus, silicium and vitamins starvation, the size of cells increased (the informations obtained from cell density and other parameters are not similar). Cell ATP content is especially linked with silicium and phosphorus concentrations in the medium, chlorophyllacontent follows mainly the nitrogen evolution, but also that one of phosphorus.The cell density measurement does not appear always to be the best way to obtain valuable data of growth‐potential of sea water. But, if several nutrients are supposed to rule this growth‐potential, and if only one method can be used, it is then the most convenient to get averaged informations.The maximum growth is obtained from low concentrations of nitrogen, iron and EDTA in the media. WithS. costatumthe best enrichments, for growth potential experiments, range from 0,25 to 1 time the chemical composition of the ASP 2 solution of PROVASOLI et al. (1957) as nitrogen, phosphorus, silicium, iron, metal mix, EDTA and vitamins are concerned. This values could be lowered with other sp

ISSN:0020-9309    

DOI:10.1002/iroh.19730580307

出版商:Akademie Verlag, Berlin    

年代:1973

数据来源: WILEY

摘要:

AbstractDARWIN's statement, that rudimentary parts of organisms are apt to be highly variable, is also true for the regressive structures of cavernicolous animals. On the other hand, adaptive traits develop under cave conditions, the variability of which is lowered rather than increased, compared to that of their precursors in the epigean population. These differences in the genetically controlled variability of constructive and degenerative features indicate action and nonaction of natural selection.

ISSN:0020-9309    

DOI:10.1002/iroh.19730580308

出版商:Akademie Verlag, Berlin    

年代:1973

数据来源: WILEY

摘要:

AbstractOver a six month period, littoral periphyton communities on vertically oriented glass slides were quantitatively sampled from four stations in Elk Lake, British Columbia. Correlation and multiple regression analyses were employed to assess the temporal interrelationships between 15 environmental variables, concurrently measured, and the periphyton populations, expressed as total cell counts and species diversity, for the complete data set of each station. At all stations there was a statistically significant increase in total cell populations with increasing length of slide exposure; positive correlations also occurred with pH, temperature, nitrite, nitrate and copper, while negative ones occurred with oxygen, orthophosphate and hardness (magnesium and total). At all but one station there was a significant decrease in species diversity with increasing slide exposure duration, a decrease attributed to the simultaneous increase in standing crop resulting in intensified competition for diminishing substrate area suitable for cell colonization. Multiple stepwise regression analyses demonstrated that greater than 80% of the variation in periphyton total cells at all four stations could be reliably predicted or described in terms of length of slide exposure, phosphate (ortho and total), and hardness (calcium and total). On the other hand, exposure duration and total cell populations were the most important variables associated with changes in species diversity at three of the four stations. In general, correlations and regressions between standing crop and environmental variables were more statistically reliable and consistent between stations than comparable analyses with species diversity. Use of multiple regression and correlation disclosed the importance of small, non statistically significant variation in ecologically relevant variables and permitted objective comparison of stations.

ISSN:0020-9309    

DOI:10.1002/iroh.19730580309

出版商:Akademie Verlag, Berlin    

年代:1973

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19730580302

出版商:Akademie Verlag, Berlin    

年代:1973

数据来源: WILEY