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1.
Dynamics of abundance and reproductive cycles of limnophileous triclads (Turbellaria) from little ponds.
  1. Studying 18 little ponds in Lower Southern-Saxonia (West-Germany), in 14 ponds seven triclad-species were found.
  2. Phagocata vitta occurs from October to July in 1–2 generations. In the area the species reproduces by fissipary. Maximum abundances and rates of reproduction are reached in December and January. In the ponds, where P. vitta and Dugesia polychroa live together, there is no competition between the two species.
  3. After dry periods Dendrocoelum hercynicum emigrates from interstitial habitats as facultative inhabitant of surface-waters.
  4. In low abundances Dendrocoelum lacteum lives in one pond only. The breeding period (production of cocoons) lasts from January to March. Low densities of this species are probable caused by interspecific food-competition with Polycelis nigra.
  5. Likewise, Dugesia tigrina inhabits only one pond. The species is competitive to P. nigra at temperatures of about 20°C. High abundances in the months July to October fall together with high fissipareous-rates.
  6. Dugesia polychroa occurs in low densities over the year or dependent on dry-periods. Cocoons are produced between March and May, in low numbers till autumn.
  7. In the stagnant pond Bursfelde Polycelis nigra is the absolute dominant triclad-species with densities of up to 800 individuals/0,I m3. The maximum-abundances are caused by two intense reproductive periods in spring and autumn, together with optimum temperatures and food conditions.
  相似文献   

2.
M. Hickman 《Hydrobiologia》1974,45(2-3):199-215
  1. The epipelic algal standing crops were increased by the discharge of thermal effluent into Lake Wabamun, particularly in the discharge canal at station (03–04) and 05.
  2. The increase in the standing crop size of the epipelon was due to Oscillatoria amoena and O. borneti in the heated area, while the discharge canal provided the inoculum of the algae for the heated area of the lake.
  3. At station (03–04) the increased standing crop size was also a function of increased light penetration to the sediment due to the heated effluent keeping an area of the lake free of ice during the winter.
  4. The species composition of the diatoms was similar at all stations except in the discharge canal where there was a reduction in the number of diatom species.
  5. Navicula cuspidate developed best in the discharge canal in the summer where water temperatures of 31°C were recorded.
  6. Amphora ovalis var. pediculus was the dominant diatom species during the winter under ice-cover.
  7. The heated effluent had no effect upon the standing crop or species composition of the epipsammon.
  8. Results obtained from the sediment core study showed that the shallow littoral zone of the lake is very disturbed due to wind-induced wave action.
  相似文献   

3.
  1. The respiratory behaviour and patterns of oxygen consumption of three Nile species have been investigated.
  2. Tilapia nilotica showed a typical pattern of oxygen consumption with an ambient region, adaptive plateau and lethal region (Fig. 2).
  3. Specimens of Polypterus senegalus and Clarias lazera (body weights 20–30 and 30–45 g respectively) showed patterns of consumption comparable to that of Tilapia (Fig. 3a and 4a). In larger specimens of the two species the adaptive plateau was either insignificant or completely absent.
  4. Specimens of Polypterus and Clarias (20–30 g and 30–45 g respectively) could survive in waters saturated with oxygen (7.4 mg/l) but their tolerance to lower oxygen concentrations was limited. Larger specimens of Polypterus and Clarias failed to survive in oxygen saturated waters.
  5. The tolerance of Tilapia nilotica to extremely low oxygen concentration is an adaptation of a tropical and completely aquatic species. Polypterus and Clarias resort to their compensatory mechanisms only when the aquatic respiratory surface fails to satisfy their oxygen requirements.
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4.
  1. From 40 waters of the Abisko-district (Sweden, Lapland) 58 samples were collected (essentially samples from sediments).
  2. It is not possible to clear the origin of all discovered tests of sediments. The bottom of most waters was covered with mosses, from which vegetation, tests can come into the sediments. But also tests from other biotopes, can be found at the bottom.
  3. Nevertheless we can recognize typical characters of those species living in sediments. The prevalent type is the “Difflugia-type”. Those species of Centropyxis which immigrated into sediments demonstrate a trend towards the “Difflugia-type”. The immigration is possible from Aufwuchs, mosses and soils. 62,7% of the recorded tests belong to Difflugia, 17,8% to Centropyxis.
  4. The prevalent species in the sediments of the Abisko-district is Difflugia elegans var. teres, the next is D. glubolosa.
  5. A great number of investigated waters contained the oligotrophic species Centropyxis aërophila. Only one lake (Ruontenjaure) shows the association of dystrophic lakes.
  6. Some species are described taxonomically, for instance: Centropyxis nauwercki n.sp. C. nauwercki is very much like Difflugia, but is also connected with C. platystoma. The new species shows a trend from Centropyxis to Difflugia.
  7. C. aërophila can also immigrate into the Aufwuchs. There the species has membraneous tests.
  8. Geographical aspects of the sediment colonization are discussed.
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5.
S. Meguro  A. Miyawaki 《Plant Ecology》1994,112(2):101-111
The mechanical properties of broad-leaf tree species in a maritime-wind exposed habitat in central Japan were examined. The broad-leaf trees studied were Celtis sinensis var. japonica, Ilex integra, Eurya japonica, Pittosporum tobira, Euonymus japonicus and Cinnamomum japonicum. The results obtained can be summarized briefly as follows:
  1. At places with weaker wind, the number of species increased and the height of the canopy increased.
  2. The fracture strength σm showed no dependence on tree part or branch thickness, but was constant.
  3. The order of strength was Celtis sinensis var. japonica > Ilex integra > Eurya japonica > Pittosporum tobira > Euonymus japonicus > Cinnamomum japonicum, and these six species could best adapt to the wind pressure in the study area.
  4. Within species, fracture strength varied directly with wind strength.
  5. The strain εm decreased as the trunk became thicker.
  6. Within species, strain energy Um varied directly with wind strength.
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6.

Introduction

Atoms theory and symmetry theory dominated physics. Symmetry propagation and interactions verify the Curie principle. But its violation by symmetry breaking is spontaneous.Fragility is creative. An information breaks a generalized symmetry. Results on symmetry breakings are not valid for fuzzy symmetries. The breaking of a fuzzy symmetry leads only to a pour symmetry (Fig.1). Homogeneity breaking, and atom of time are not usual concepts. We examine in this work symmetry breakings which generate the living time.

Relativistic Time-Space Breaking

  1. Medium and environment of living define ordinary referential of space and referential of time. Astronomical phenomena following classical mechanics and microphysical phenomena following quantum mechanics can be written with the same t coordinate.
  2. Relativity corrections. Schrödinger's Quantum mechanics (Eq.0) approximately governs molecular systems (Relativity corrections can be expressed as physical effects in the above defined referential).
  3. Time reversal symmetry. The well-known Wigner's transformation determines the microscopic reversibility.
  4. The three essential particle-vacancy equilibria. This transformation is verified by all particle-vacancy reciprocity. Vacancy moves like particle but with negative moment and positive kinetic energies. Only three biochemical equilibria admit this time reversal symmetry, namely: oxydo-reduction, acido-basicity, fluidity-viscosity. In these case, reacting electron, solvated proton, water molecule are respectively antagonist of the corresponding vacancy.
  5. Fuzzy character of time reversal symmetry. Dirac's equation does not admit this symmetry which only appears at the “non relativistic” limit of quantum phenomena. Hence particle-vacancy reciprocity is fuzzy according to the experimental evidence. (Laforgue et al., 1988).

Oriented Time

  1. From the universal reversible time, an additional breaking generates the oriented time, both in the astronomical and in the living matter.
  2. Irreversibility for the environment. We refer to Prigogine and Stengers (1988).
  3. Irreversibility for the living matter. We refer to Lochak (1986). Because equation (0), above discussed, is “microreversible” the second breaking could come from an additional term vanishing in the stationary states but increasing with time in evolutionary processes.
  4. Negative times. Taking into account the fuzzy character of the time reversed symmetry, the third breaking cannot suppress completely the occurrence of negative times. Reversed time is controlled by direct time. Except in the three above reported cases, time reversal symmetry is not verified by the medium. Free motion of the particle following eg.(0) or of the vacancy following time reversal reciprocal equation takes place only during short jumps from an interaction site to an other. Fig. 2 schematizes the law of motion of the electric charge corresponding to the transport by proton or by proton vacancy in an unitary field (fluctuations are neglected). The reserved jumps are estimated in the range of 10?12s. It is not excluded that such a jump can control a direct phenomenon.
  5. The living time. Biological phenomenon appears as an oriented set of events. Nevertheless latency or exaltation phases could be perceived. This modulation could be described by positive and negative times additional to the basic time. (Negative can be interpreted as above)

Living produces Time

  1. That were not understandable, if time was only a frame, in which change occurs. Taking chance as frame and time as effect, we regard biological activity as integrating reversible and irreversible time. Living synchronizes internal and external time by its own effort as it results (Lestienne, 1990) from Chronobiology.
  2. Time modulation. Let us consider the dy1...dyi...dyp changes in the variables of the systems, dy={dyi} has produced dt. We proof (eq.(1) to (4)) that time is modulated by a φ(y) speed coefficient depending on the medium. tmodulated=tφ (y) ?1
  3. The production of reversible time (e.g.acido-basicity) determines time modulation. As above reported it remains some reversibility effects (jumps of negative time) which modulate time. E.G., if an important amount of reagent is necessary to modify an acid-base equilibrium, φ(y) is small.
  4. Time modulation and activation-repression reciprocity. As well-known, long tmodulated means repression, short tmodulated means exaltation. Extrema of ? are symmetrical because particle and vacancy are reciprocal. Nevertheless reciprocity is not perfect. E.g., on fig. 3, the wet receptor determines the cell increasing, the dry receptor the cell senescence of a certain alga (Lück, 1962).
  5. Irreversible time production. Medium accepts entropy. Hence it acts in the second breaking of time. Living extracts the free energy from the medium, like a dissipative structure. That insures an operative point far from the thermodynamical equilibrium.

Consumption of Time

  1. The three followings correspond to the more trivial time consumption.
  2. Rhythmical time. Free energy flux is favourable to the arising of order in space or time. This later gives a structure to the living time.
  3. Mutual dependence of reversible time and rhythms. Time irreversible structure can be controlled by the above considered particle-vacancy equilibrium. Consequently the living time (modulated and structured) is a chemical time connected to molecular properties and to statistical thermodynamics. Practically, the connection between chronobiology and chemistry is important. The use of drugs could be interpreted as a response to an aggression against biorhythms.
  4. Lifetime. The dead-birth rythm can be broken in two ways: evolution or indefinite life. This later is non exceptional for the living matter, e.g. in the vegetals where it is connected with the chlorophyllic assimilation; the time reversal significance of which is evident.
  5. The plan of the alchemist. Indefinitely life has fascinated individuals. Do the human species becomes better adapted by a longer life?

Conclusions

  1. Atoms of time could exist.
  2. Biological time is defined by the breaking of five generalized symmetries, namely: Minkovski's space symmetry, reversibility, homogeneity, rhythmicity, generations reproduction.
  3. Environment and medium determine non relativistic, oriented, structured time.
  4. At the microphysical scale, a fuzzy time reversal symmetry takes place, the breaking of which is not complete. Reversible time and dominating irreversible time are integrated in living phenomena.
  5. Three fundamental particle-vacancy reciprocities admit a part of reversibity. Irreversibility governs the all others phenomena.
  6. Time is produced chemically.
  7. A new perspective is the connection between chemical equilibria and rhythms including the time of the life.
  相似文献   

7.
  1. Growth of the floating aquatic weed, Salvinia, in sterile culture was exponential for at least 2 weeks under standardized conditions.
  2. Increase in light intensity or in CO2 resulted in increases in growth rate, but did not extend the exponential period of growth.
  3. This aquatic plant, like many others, discriminates against calcium relative to strontium.
  4. In culture Salvinia exhibited luxury consumption of N and P.
  5. Because of high C/N ratios, Salvinia may not be a favorable source of animal food, but might be useful in nutrient removal schemes.
  6. In sterile culture, S. molesta produced fewer leaves than S. minima, but maintained a significant increase in leaf area and dry weight. This may be correlated with the ability of the first species to rapidly spread over tropical waterways.
  相似文献   

8.

Introduction

Atoms theory and symmetry theory dominated physics. Symmetry propagation and interactions verify the Curie principle. But its violation by symmetry breaking is spontaneous.Fragility is creative. An information breaks a generalized symmetry. Results on symmetry breakings are not valid for fuzzy symmetries. The breaking of a fuzzy symmetry leads only to a pour symmetry (Fig.1). Homogeneity breaking, and atom of time are not usual concepts. We examine in this work symmetry breakings which generate the living time.

Relativistic Time-Space Breaking

  1. Medium and environment of living define ordinary referential of space and referential of time. Astronomical phenomena following classical mechanics and microphysical phenomena following quantum mechanics can be written with the same t coordinate.
  2. Relativity corrections. Schrödinger's Quantum mechanics (Eq.0) approximately governs molecular systems (Relativity corrections can be expressed as physical effects in the above defined referential).
  3. Time reversal symmetry. The well-known Wigner's transformation determines the microscopic reversibility.
  4. The three essential particle-vacancy equilibria. This transformation is verified by all particle-vacancy reciprocity. Vacancy moves like particle but with negative moment and positive kinetic energies. Only three biochemical equilibria admit this time reversal symmetry, namely: oxydo-reduction, acido-basicity, fluidity-viscosity. In these case, reacting electron, solvated proton, water molecule are respectively antagonist of the corresponding vacancy.
  5. Fuzzy character of time reversal symmetry. Dirac's equation does not admit this symmetry which only appears at the “non relativistic” limit of quantum phenomena. Hence particle-vacancy reciprocity is fuzzy according to the experimental evidence. (Laforgue et al., 1988).

Oriented Time

  1. From the universal reversible time, an additional breaking generates the oriented time, both in the astronomical and in the living matter.
  2. Irreversibility for the environment. We refer to Prigogine and Stengers (1988).
  3. Irreversibility for the living matter. We refer to Lochak (1986). Because equation (0), above discussed, is “microreversible” the second breaking could come from an additional term vanishing in the stationary states but increasing with time in evolutionary processes.
  4. Negative times. Taking into account the fuzzy character of the time reversal symmetry, the third breaking cannot suppress completely the occurrence of negative times. Reversed time is controlled by direct time. Except in the three above reported cases, time reversal symmetry is not verified by the medium. Free motion of the particle following eg.(0) or of the vacancy following time reversal reciprocal equation takes place only during short jumps from an interaction site to an other. Fig. 2 schematizes the law of motion of the electric charge corresponding to the transport by proton or by proton vacancy in an unitary field (fluctuations are neglected). The reserved jumps are estimated in the range of 10?12s. It is not excluded that such a jump can control a direct phenomenon.
  5. The living time. Biological phenomenon appears as an oriented set of events. Nevertheless latency or exaltation phases could be perceived. This modulation could be described by positive and negative times additional to the basic time. (Negative can be interpreted as above.)

Living produces Time

  1. That were not understandable, if time was only a frame, in which change occurs. Taking change as frame and time as effect, we regard biological activity as integrating reversible and irreversible time. Living synchronizes internal and external time by its own effort as it results (Lestienne, 1990) from Chronobiology.
  2. Time modulation. Let us consider the dy1...dyi...dyp changes in the variables of the system, dy={dyi} has produced dt. We proof (eq.(1) to (4)) that time is modulated by a Φ(y) speed coefficient depending on the medium. tmodulated=tΦ-1 (y)
  3. The production of reversible time (e.g.acido-basicity) determines time modulation. As above reported it remains some reversibility effects (jumps of negative time) which modulate time. E.g., if an important amount of reagent is necessary to modify an acid-base equilibrium, Φ(y) is small.
  4. Time modulation and activation-repression reciprocity. As well-known, long tmodulated means repression, short tmodulated means exaltation. Extrema of ? are symmetrical because particle and vacancy are reciprocal. Nevertheless reciprocity is not perfect. E.g., on fig. 3, the wet receptor determines the cell increasing, the dry receptor the cell senescence of a certain alga (Lück, 1962).
  5. Irreversible time production. Medium accepts entropy. Hence it acts in the second breaking of time. Living extracts the free energy from the medium, like a dissipative structure. That insures an operative point far from the thermodynamical equilibrium.

Consumption of Time

  1. The three followings correspond to the more trivial time consumption.
  2. Rhythmical time. Free energy flux is favourable to the arising of order in space or time. This later gives a structure to the living time.
  3. Mutual dependence of reversible time and rhythms. Time irreversible structure can be controlled by the above considered particle-vacancy equilibrium. Consequently the living time (modulated and structured) is a chemical time connected to molecular properties and to statistical thermodynamics. Practically, the connection between chronobiology and chemistry is important. The use of drugs could be interpreted as a response to an aggression against biorhythms.
  4. Lifetime. The dead-birth rhythm can be broken in two ways: evolution or indefinite life. This later is non exceptional for the living matter, e.g. in the vegetals where it is connected with the chlorophyllic assimilation; the time reversal significance of which is evident.
  5. The plan of the alchemist. Indefinitely life has fascinated individuals. Do the human species becomes better adapted by a longer life?

Conclusions

  1. Atoms of time could exist.
  2. Biological time is defined by the breaking of five generalized symmetries, namely: Minkovski's space symmetry, reversibility, homogeneity, rhythmicity, generations reproduction.
  3. Environment and medium determine non relativistic, oriented, structured time.
  4. At the microphysical scale, a fuzzy time reversal symmetry takes place, the breaking of which is not complete. Reversible time and dominating irreversible time are integrated in living phenomena.
  5. Three fundamental particle-vacancy reciprocities admit a part of reversibility. Irreversibility governs the all others phenomena.
  6. Time is produced chemically.
  7. A new perspective is the connection between chemical equilibria and rhythms including the time of the life.
  相似文献   

9.
  1. A collection of polychaetous annelids made by the Japanese research vessel ‘Umitaka-Maru’ in December 1968 from the Arabian Gulf was examined.
  2. Seventeen species, belonging to twelve families, are identified.
  3. Two pelagic families (Alciopidae, Tomopteridae) and five species (Plotohelmis capitata, Tomopteris sp.,Autolytus cf.A. longistaffi, Lysidice ninetta, Pista cristata) are recorded new to the fauna of the Arabian Gulf.
  相似文献   

10.
High atmospheric deposition of ammonium affects the physical and chemical status of the soil, increasing nitrogen availability, soil acidity and the mobilization of toxic metal ions. To investigate whether and how the decline of several herbaceous plant species in Dutch heathlands is associated with these processes, the chemical composition of the soil on which these species grow has been compared with the soil on which heathland species such asCalluna vulgaris (L.) Hull,Erica tetralix L. andMolinea caerulea (L.) Moench dominate. The discrimination between both soil types was primarily based on differences in pH (H2O), pH (NaCl) and the aluminium/calcium ratio in the waterextracts. Within the group of endangered herbaceous heathland species these soil parameters also varied. This led to a division into 4 groups of species:

u

  • Dominating species growing on acid soils
  • Herbaceous species growing together with dominating species on acid soils
  • Herbaceous species growing together with dominating species on moderately acid soils
  • Herbaceous species growing together with dominating species on weakly acid soils.
  • This study indicated that, unlike the decline of heather species, the decline of herbaceous species is not likely to be due to increased competition from grass species as a result of eutrophication. Soil acidification and the changed mineral balance in the soil are most likely to be responsible for the decline of all three groups of herbaceous plant species. ei]R F Huettl  相似文献   

    11.
    1. Specific activity of amylase, cellulase, protease and lipase in the intestines of the air-breathing catfish, Clarias batrachus (Linn.) has been studied.
    2. Excepting amylase and protease, the activity of lipase and cellulase showed practically no changes with change in the nutritional status of the diets.
    3. pH optima of all enzymes were between 6.9 and 7.6
    4. There is reason to believe from cellulase and high amylase activity in the intestine of the species that its culture operation could be done more economically by giving them a supplementary diet from indigeneously available raw material particularly from plant origin.
      相似文献   

    12.
    1. Aster tripolium is a very variable species of which a number of types have been described both on a morphological and ecological level.
    2. In permanent plots along the height gradient in the salt marsh it appeared that differences in the A. tripolium subpopulations occur.
    3. In the lowest zone of the marsh, dominated by Spartina anglica (Spartinion), the mean life expectancy of individual adult plants is relatively high but it is relatively low for seedlings.
    4. In the higher zones of the marsh the mean life expectancy is relatively lower, but for the seedlings it is higher (Puccinellion maritimae).
    5. In the Spartina-zone individual A. tripolium plants have about twice the number of shoots as the plants from the other zones.
    6. The plants from the Spartina zone produce per individual more generative shoots (absolute) but these have less capitula than elsewhere in the marsh. The number of ripe seeds per head is almost constant everywhere in the marsh.
      相似文献   

    13.
    T. Kamaya 《Mycopathologia》1969,37(4):320-330
    Young colonies of Sabouraud's glucose agar room temperature culture ofCandida species from human isolation were suspended in distilled water. The suspension was mixed with a solution of lysozyme and incubated in a 37° C water bath. Within 3–5 hours, various species ofCandida cells showed flocculation to varying degrees which occurred at varying periods of onset. Among sevenCandida species,Candida albicans andCandida stellatoidea showed the strongest flocculation, earliest onset and most solution clarity than did any other species.Candida stellatoidea was indistinguishable fromCandida albicans in its degree of flocculation, and in the clarity of solution.Candida species may be arranged in the following order according to their decreasing positivity in flocculation:
    1. Candida albicans
    2. Candida stellatoidea
    3. Candida tropicalis
    4. Candida krusei
    5. Candida pseudotropicalis
    6. Candida parapsilosis
    7. Candida guilliermondii
    8. Saccharomyces species may be placed afterCandida guilliermondii.
    It seems possible to separate theCandida species into 3 groups by the rate of flocculation, and clarity of solution. Group I.Candida albicans andCandida stellatoidea. Group II.Candida tropicalis, C. krusei andCandida pseudotropicalis. Group III.Candida parapsilosis andCandida guilliermondii. Saccharomyces specimens (S. cerevisiae and others) were placed after group III.  相似文献   

    14.
    J. Rzedowski 《Brittonia》1972,24(4):398-402
    1. -Bigelowia pyramidata Rob. & Greenm. from Oaxaca proves to be a dioecious plant and is therefore transferred to the genusBaccharis.
    2. -Baccharis matudae sp. nov. is described on the basis of material collected in Zacatecas and San Luis Potosí. The species is closely related toB. pyramidata (Rob. & Greenm.) Rzedowski.
    3. -Baccharis zamoranensis sp. nov. is described on the basis of material collected on the border of Querétaro and Guanajuato. The taxon is related toB. multiflora H.B.K., known from central and southern Mexico.
      相似文献   

    15.
    Forest regeneration in the vegetation complex of the submontane belt in the Southern Alps involves the active participation ofOstrya carpinifolia woods and their wood edge communities. The corresponding syndynamical processes are described by employing phytosociological, phytogeographical and ecological methods. It is concluded that:
    1. The communities of the grassland-wood transition are of major importance in the successional developments in this man-made vegetation complex.
    2. Many species occurring in the region of the deciduous forests of Eurasia find their refuge in such transitional communities and are supposed to play an important part in the succession.
    3. Ostrya carpinifolia is considered as an early successional tree species.
      相似文献   

    16.
    17.
    1. Rhizopod tests from 16 cores of sediments from lake Latnjajaure, in Swedish Lapland, were studied and found to show the development of the lake since its formation. Latnjajaure is a oligotrophic mountain lake.
    2. All cores contained many remains of rhizopods, most of them intact. Most broken tests could be reconstructed. Postglacial development of a lake could thus be elucidated for the first time.
    3. The sediment cores contained 24 species of Testacea, 41.6% of the recent fauna. The rank order of species forming 1 % or more of the total number in the cores is nearly identical with the rank order of recent species.
    4. The history of lake Latnjajaure is characterized by Centropyxis aërophila, an oligotrophic species. Periods of beginning eutrophication are indicated by a decrease of Centropyxis aërophila and an increase of Difflugia species, but typical eutrophic species were absent. A dystrophic phase in the development could not be ascertained by means of rhizopods.
      相似文献   

    18.
    Chua Thia-Eng 《Hydrobiologia》1973,43(3-4):505-533
    1. An ecological study of the Ponggol Estuary was conducted from July 1965 to June 1966 and the seasonal data on physical, chemical and biological characteristics were presented.
    2. The Ponggol River represents a short, narrow and shallow estuary in Singapore. The river mouth is open throughout the year and water from eastern Johore Straits drains in twice a day at high tide. The upper reach, however, is left exposed at low tide.
    3. The Ponggol River was classified as a vertically and laterally homogeneous estuary and was found to exhibit a mesohaline to polyhaline environment.
    4. Significant hydrological gradients from the river mouth 10 the upper reach were noted in the river system. Salinity, dissolved oxygen and pH increased towards the mouth of the river and other parameters such as nutrients, dissolved organic matter and turbidity increased towards the source.
    5. Although the river received organic pollutants at the upper reach the estuary was able to discharge them fairly rapidly through regular flushing by the tides. The transient rise of organic matter did not appear to impart any serious affect on the biota in the estuary.
    6. Over 98% of the phytoplankton consisted of diatoms, most of which were brought into the estuary from eastern Johore Straits. Freshwater forms were relatively few.
    7. Phytoplankton biomass was considerably higher than the adjoining waters. and was reduced at the upper reach due to high turbidity of the water.
    8. 80% of the zooplankton was composed of dinoflagellates,Difflugia, copepods and bivalve larvae dominating at all sections of the estuary.
    9. Percentage composition of the zooplankton showed that dinoflagellates and copepod nauplii predominated at high tide whileDifflugia and bivalve larvae were abundant at low tide.
    10. Zooplankton standing crop, in general, was higher towards the source at high tide but the reverse was found at low tide, i.e. standing crop increased towards the river mouth. This was attributed to the process of concentration.
    11. Species composition of zooplankton was found to be more or less similar to that of the eastern Johore Straits.
    12. The nekton consisted predominantly of small and juvenile fish. Close correlation of fish and copepods was found to be statistically valid and it was concluded that the fish entered the estuary to feed rather than to spawn.
    13. The squids formed an important catch of the beach seine unit and were caught throughout the year.
    14. The fish population could be grouped into four categories: estuarine components, euryhaline components, marine components and migratory components.
    15. Benthic invertebrates were abundant. Commercially important species consisted of prawns,Metapenaeus andPenaeus, and crabs,Neptunus pelagicus andScylla serrata.
    16. The river bed was inhabited predominantly by molluscs and the distribution resembled that of the sheltered shore of muddy-sand type.
      相似文献   

    19.
    1. A fully automated phototaxis monitoring device is described for measuring photo-topatactic responses of flagellated organisms.
    2. Photokinesis can be demonstrated in Chlamydomonas cells only after a dark period of about 72 hrs.
    3. Pre-darkening of a few hours duration raises the phototactic disposition, whereas pre-illumination has no significant effect.
    4. Circadian rhythms can be initiated by only one period of darkness or lower light intensity, whereas a period of higher intensity does not induce rhythms. The period length of the circadian rhythms is about 24 hrs.
      相似文献   

    20.
    U. H. Mane 《Hydrobiologia》1975,47(3-4):439-451
    1. The neutral red technique was employed to study the rate of filtration in Katelysia opima.
    2. The weight specific water filtration was found to be greater for younger clams compared to the older ones.
    3. The rate of water filtration increased with decreasing salinity.
    4. Water filtration was found to increase as temperature increased, reaching a maximum at 35°C. but then sharply decreasing at 39°C.
    5. Light had no significant effect on the rate of filtration.
    6. Suspended matter was found to affect the rate of water filtration.
    7. The rate of filtration was low at high pH and high in low pH.
    8. The rate of water filtration was found to be faster during high tide than during low tide.
    9. The presence of the parasitic crab, Pennotheris sp., in the mantle cavity of clams had a marked effect on the particle filtration.
    10. Accidental cut of the siphon tips had no effect on the rate of filtration.
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