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The association of many environmentally sensitive chemicals and their transformation products with mineral and organic substrates is of considerable importance for environmental monitoring, prediction and management purposes in rivers and their basins. Our understanding of these relationships is poor. This paper reviews processes of particular concern, including the physical behaviour of fine-grained (< 63 µm) sediment in freshwater; the role of flocculation as a transport vector; the processes that control freshwater flocculation including microbiological factors; the uncertainty in conventional sediment transport models for predicting pathways of sediment-associated chemistry; the relationship between suspended sediment and toxicity in the water column; and the partitioning of chemicals between the sediment, organic and water phase, including the significance of these in predicting chemical transport on suspended matter.

The relationships between cultivated fish species and their environment is largely dependent on the biological characteristics of the fish and the degree of intensification of the culture. In extensive and semi-intensive systems, based on natural production, stocking fish species of different feeding habits together enables a more efficient utilization of pond resources. In polyculture systems only a proper combination of ecologically different species at adequate densities will utilize the available resources efficiently, maximize the synergistic fish-fish and fish-environment relationships and minimize the antagonistic ones. Synergistic interactions among fish species may be explained on the basis of two interrelated processes: increase of food resources and improvement of environmental conditions. Antagonistic interactions occur between incompatible species combinations and when the stocking rates are balanced; in this case, the way the system is affected depends on the food chain level were the imbalance occurs. Several examples of synergism and antagonism at different levels of the food chain are analyzed in this paper. The knowledge of fish-fish and fish-environment quantitative relationships enables choosing adequate combinations of fish species, stocking rates, input types and rates, and other management decisions according to the specific local conditions: climate, quality of water supply and pond fertility, availability of fish fry and fingerlings, availability of feeds and fertilizers, and market requirements.

Halicryptus spinulosus (Priapulida) is extraordinarily resistant to hydrogen sulfide. As described previously, the body wall of specimens from oxic and from hydrogen sulfide-contaminated habitats differs strikingly in colour. In the present paper the ultrastructure of the body wall of specimens kept under oxic conditions is described. These findings serve as a reference for changes induced by exposure to hydrogen sulfide. There are marked ultrastructural differences between epidermal and muscular mitochondria exposed to hydrogen sulfide. Epidermal mitochondria of individuals subjected to hydrogen sulfide are often associated with dense granules of unknown composition. Findings are compared with those from other taxa which may encounter hydrogen sulfide in their environment.

Variations in physiological state and biomass of the phytoplankton community were examined in three different types of lakes, namely Lake Barato, Lake Akan, and Lake Shikaribetu. When the physiological state of the phytoplankton community was estimated by its adenylate energy charge (AEC), low biomass and low physiological state co-appeared gradually in the metalimnion and hypolimnion during stratification. The physiological state of the phytoplankton as estimated by its AEC value did not always correspond to its biomass, estimated by chlorophyll-a and ATP in these three lakes. A high physiological state of the community was usually observed in the euphotic zone, but the low AEC value observed in the euphotic zone of Lake Barato was not identified in the euphotic zones of the other lakes. Thus, the relationship between the value of AEC, and biomass of phytoplankton is a complex variable, which is further discussed in this paper.

This paper details attempts to breed members of the L. saxatilis species complex in the laboratory and to construct interspecific hybrids between them. Success in reciprocal crosses between animals from the type localities of the ‘species’ of Littorina saxatilis (Olivi) and Littorina rudis (Maton) indicates that these two taxa are synonymous. Six of the twelve possible reciprocal hybridisation crosses between the four species (L. saxatilis, L. arcana Hannaford Ellis, L. nigrolineata Gray and L. neglecta Bean) have been attempted, with only one proving successful, that between male L. saxatilis and female L. arcana. This hybrid cross produces viable offspring, although at a lower frequency than either of the parental crosses in the laboratory, while the reciprocal cross has, as yet, proved unsuccessful. Limited work on the F1 hybrids shows them to be inter-fertile and also capable of backcrossing with male L. saxatilis, but not with female L. saxatilis or L. arcana. Details are also given of attempts to find natural hybrids in sympatric populations of the species of the complex, using gel electrophoresis.

This review of Brazilian Amphipod works is arranged in a chronological list and points out the significant works for each one of the four arbitrary periods. Besides that, this paper deals with the distribution of 83 species of Brazilian Gammaridea and Caprellidea in relation to bathymetry, substrate, latitude and thermal region.

Exploitation of the commercially-important species of Gelidium in Spain (G. sesquipedale and G. latifolium) and development of the industry occurred after World War II, as a consequence of their use as resources for the extraction of agar. This resulted in the implementation of several harvesting methods, the most important of which is the gathering of cast seaweeds, both from the shore and the sea. From the very beginning, direct exploitation of these species (i.e. plucking) was controversial because of possible adverse ecological effects. Consequently, several biological and ecological studies of both species of Gelidium were begun. This included such aspects as growth, biomass production, productivity, reproduction, regeneration capacity and agar yield. Recently, the growing interest in using and conserving this resource has led to increased knowledge of the biology and ecology of these species. In this paper, we provide an overview of the research carried out by different Spanish groups and suggest guidelines for rational management of these resources.

The supply of Gelidium resources is dependent on collection from natural habitats. As these resources are very limited, one possible means of augmenting production is by implementation of artificial cultivation as has been done with Laminaria, Porphyra and Eucheuma. Chinese phycologists have conducted research on sporeling and field cultivation of Gelidium for many years. Trials have been made using: (1) raft cultivation based on vegetative propogation of thallus fragments, (2) cultivation based on spore-collecting and land-based tank culture to provide seedstock, (3) cultivation based on regeneration from small thallus fragments to provide seedstock. Some of these results have been promising, but development remains at the experimental stage and methods of cultivation need to be improved. This paper is an updated review of the research and development on artificial sporeling production and field cultivation of Gelidium in China.

Ciliary organelles play important roles in many of the locomotory and sensory functions of ctenophores. This paper reviews published work on the physiology and behavior of ciliary-based feeding in Pleurobrachia pileus and presents recent preliminary work on the conduction pathway controlling this behavior. The feeding response can now be described in terms of specific physiological events at most levels of organization.

This paper presents the results of an extensive and detailed survey conducted in 1985 on the biology, bacteriology and levels of heavy metals in subtidal sediments of the Humber estuary. The findings of the investigation are assessed with respect to environmental quality. Abundance and distribution patterns of the indicator species Capitella capitata, the numbers of faecal bacteria, and levels of heavy metals and organic matter are examined in relation to areas of sewage disposal. The possible effects of inputs from the Humber to the North Sea are discussed.

An important fishery for the West African hemi-estuarine clam, Egeria radiata exists in the lower reaches of the Cross River (CR) system. The stock is heavily exploited but its productivity and potential yield have not been studied. This paper discusses the distribution and ecology of, and presents data on growth, abundance, mortality, biological production and potential yield of the CR stock of E. radiata based principally on length structured relative age. Growth was exponential and conformed to the von Bertalanffy's growth model (VBGM), with the parameters L∞ = 9.3 cm, K = 0.36 and To = −0.10 year. The instantaneous total mortality coefficient (Z) by the catch curve method was 0.82 yr−1; natural mortality coefficient (M) was estimated at 0.32 yr−1. Total mean biomass computed from data obtained in two month's grab sample surveys in the area of occurrence of E. radiata was 1923 kg ha−1 for total (i.e. flesh + shell) and 628 kg ha−1 for flesh (i.e. shell-free) production units. The production-to-mean-biomass (or P/B ratio, R′) were 0.31 and 0.52 for total and shell-free production units respectively. The maximum sustainable yield (Ymax) was estimated at 398.4 kg ha−1 for total and 112.2 kg ha−1 for shell-free production units. With an exploitation ratio (E) of 0.61 and an estimated present catch rate of 1970 tonnes(t) yr−1 total weight (or about 82% of Ymax) the Egeria stock of the CR is currently being fished above the level of its optimum yield. Much of the fishing pressure is on the very young clams, thus lowering the age at first capture (Tc) to 1 year. This is an unhealthy situation for a species with limited area of distribution and low (< 1.0) P/B ratio; it can lead to rapid extinction of the stock if for some reason there is a substantial reduction in annual recruitment. It is recommended that in order to conserve this valuable resource and keep it at a level of sustained optimum yield, there should be a regulation prohibiting the landing of young clams (< 6.0 cm shell length). Furthermore the fishermen should learn to cultivate the animal by transplanting the young clams to new beds upstream to give them time to grow larger before harvesting. This type of management has been practised in Ghana for a long time and has helped to conserve the Egeria stock of the Volta River. The need for a continuous monitoring of the effluents from the Nigerian Newsprint Manufacturing Company's factory located at the bank of the CR in the centre of the clam industry is stressed; such monitoring would ensure that dangerous toxic chemicals are not discharged into the river to damage the Egeria industry.

The status of the four currently recognised species in the Littorina saxatilis species-complex, i.e. Littorina nigrolineata Gray, L. arcana Hannaford Ellis, L. saxatilis (Olivi) and L. neglecta Bean is reviewed briefly, with notes on their characteristic features and location on the shore. Since the taxonomy of these rough periwinkles has only become stable relatively recently much of the previously published information on distribution is of little or no use. In this paper their distribution around the coastline of England and Wales (with some notes on Scotland) is described and discussed. L. saxatilis is found in a wide range of habitats from exposed peninsulas to estuaries on all shores where there is a suitable rocky or stony substrate; also in salt marsh pools. L. arcana has a more restricted distribution and is notably absent along much of the south English coast, central Cardigan Bay and possibly northern Scotland; it is not found in estuaries. L. nigrolineata has an even more restricted distribution, although it occurs both on exposed coasts and in estuaries; it has only been found by us in one locality on the east coast. L. neglecta is probably fairly widely distributed but we have few details so far. The implications of the different patterns of distribution are discussed.

The genus Littorina has been subject to many studies of electrophoretically detectable variation, mostly aimed either at clarifying questions concerned with population structure, or at clarifying difficult taxonomic/systematic problems. This paper reviews many of these studies. Topics covered include Hardy-Weinberg deviations, the extent of genetic differentiation among populations within species, founder effects and the effects of human introductions on genetic variation, the biological significance of allozyme variation, and the uses of allozyme variation in Littorina systematics.

This paper presents data on the ionic composition of tropical pond waters. The discussion is on the major cations calcium (6.58 p.p.m.) and sodium (3.79 p.p.m.) and the anions bicarbonate (20.24 p.p.m.) and sulphate (21.69 p.p.m.). Some ponds have extremely low alkalinity (10 to 27 p.p.m.) and most of the ponds have poor dissolved calcium content (2.5 to 9.9 p.p.m.). Their pHs lie between 6.71 to 7.70 except the control pond F1 which has a pH of 5.21. The chemical data show differences in the ionic composition between the various ponds of different sizes. The differences can be due to the accumulated organic matter, types of fish stocked and the supplementary feeds used in the ponds.

This paper presents the preliminary observations on the interstitial fauna of the south-west coast of India, made during the course of 1963–1964. Observations were made at four stations representing different ecological habitats. The influence of some factors, such as wave action, grain size, temperature and salinity on the fauna was studied. The occurrence, seasonal abundance and the nature of distribution of the different groups on the intertidal zone, were also studied at the four stations.

This paper is the fourth of a series covering the crustose corallines of the Gulf of Maine. Information on anatomy, cytology and the development of the reproductive structures is presented to show that Lithothamnium and Leptophytum (new genus) are distinct from Clathromorphum and Phymatolithon. An additional species, P. lenormandi, is placed in Phymatolithon. The reproductive patterns and geographic and bathymetric distributions of the five species involved are presented and discussed.

1.In 1916 AugustKroghcalled attention to the fact that related species, or animals belonging to the same species, sometimes inhabit localities with extremely different temperatures. In such cases it would appear unlikely from a teleological point of view that the respiratory exchange should differ as much as the temperature difference would ordinarily imply. According to K roghone would expect that animals living at a very low temperature should show a relatively high metabolism compared with others living normally at a high temperature.2.The hypothesis advanced by Kroghwith special reference to greattemperature differences has been treated in this paper with reference to a fairly smalland seasonaltemperature difference: The temperature difference in summer between a lake, Rørbæk Sø, having a temperature of 18°, and a brook, Funder Aa, with a temperature of 11° C. In both localities there was a large population of Ancylus fluviatilisand this species was used as the experimental animal.3.The comparative experiments were carried out at 11° C and 18° C for both the cold-water form of Ancylus fluviatilisfrom the brook and the warm-water form from the lake.4.The experiments have shown nosuch acclimatization with regard to the oxygen consumption of the two Ancylus fluviatiluspopulations that live in different temperature environments, as was expected according to the above-mentioned hypothesis. But there exists an acclimatization of the oppositenature (a “reversed acclimatization”): The animals from the summer-warm environment (18° C) had acquired a greater oxygen consumption than those from the summer-cold environment (11° C).5.Aug.Krogh(1914, p. 504) established a curve showing the quantitative relation between the temperature and the standard metabolism in animals. The increasein the oxygen consumption of Ancylus fluviatiliswith increasing temperature — as found in the experiments at 11° and at 18° C — agrees well with Krogh's curve.6.The oxygen consumption increases 1.9 times when the temperature of the experimental animals increases from 11° C to 18° C. The “reversed acclimatization” found for Ancylus fluviatilisis about 1.4. It means that the observed respiration of the warmwater animals in relation to that of the cold-water animals is about 1.4 times greater than would be implied from the temperature difference between their habitats.7.The oxygen determinations made in this study were carried out by means of the polarometric method.

The paper presents data on primary productivity and phytoplankton communities in new experimental ponds which received the following treatments; ammonium nitrate and triplesuperphosphate, triplesuperphosphate, cracked corn (10% crude protein) and Auburn No. 3 fish feed (36% crude protein). Comparative data on algal communities were also obtained from production ponds which received feeds or fertilizers. Basic ecological data on macro-algae are also presented.

The physico-chemical characteristics as well as floristic and faunistic life of the seven thermal springs and one cold spring of Bakreswar, West Bengal form the basis of this paper. A compendium pertaining to the origin, geology and morphometry of these springs has been incorporated in brief.

This paper outlines the techniques used for the laboratory transmission of C. opifexito its host larva Aedes australis, which is a brackish water mosquito. The main requirements for infection are (a) a suitable medium of low salinity, consisting of natural australispool water or soil infusion prepared in the laboratory (b) inoculum containing a high concentration of active zoospores and (c) temperatures approaching summer conditions. In australispool water infected larvae appear from day 9 till day 20 with a steep rise in number at the beginning and another at the end of the cycle. In the soil infusion infection is detectable at the later time of 16 to 28 days with a single peak between days 18 to 20. The early infected larvae are probably eliminated in infusion medium due to the presence of toxic substances. Temperature has a direct effect on the time taken for infection to show up in the larvae. The use of fluorescent light, simulating daylight appears to be uncritical.

The paper describes in detail the male of the genus Hermilius for the first time. Though the males were collected along with females of H. pyriventris they cannot be assigned with certainty to any of the known species. Hence the specimens are described without specific name.

The paper is based on the monthly fluctuations of various chemical constituents studied at three stations established at different depths. It includes a discussion on the horizontal and vertical distribution of different chemical factors and their relationship with the distribution of plants in the lake. The factors studied are dissolved oxygen, free carbon dioxide, pH, alkalinity, specific conductivity, sodium, potassium, total hardness, calcium and magnesium.

A systematic account of 81 species of free living ciliophora found living in dirty water of gutters, ditches, wells, tanks etc. belonging to 31 families of Euciliata and Suctoria is given in this paper. It includes 30 new records for the Indian sub-continent and 37 new records for the Southern region.

The ecology of Euglenineae was investigated for two years in certain polluted and unpolluted environments of Hyderabad, India. The paper includes discussions regarding the distribution and periodicity of euglenoid population in relation to the physicochemical complexes which existed in the three ponds during the period of investigation. Sewage and Garden Ponds were found to be considerably polluted, whereas, the Typha Pond was comparatively pure and less polluted. Sewage Pond exhibited the highest percentage of Euglenineae harbouring 13 species and Garden Pond harboured 2 species in large numbers. Typha Pond harboured typically Trachelomonas hispida and Euglena Sp. which were totally absent in the other two ponds. It seems that high average concentrations of free CO2 were favourable for euglenoid growth in Sewage Pond and the oxygen deficiency was helpful to trigger the oxygen-iron-phosphate complex, releasing larger quantities of phosphorus and iron. Higher average values of percent Cl + NO3 ratio were found to be responsible for the luxuriant growth of these flagellates and it was suggested that inorganic sources of nitrogen might be more important in their ecology as fluctuations of nitrate coincide closely with those of Euglenineae in all ponds. These flagellates were found to be abundant during the periods when water was not rich in total sulphides and concentrations higher than 2.0 ppm adversely effected the euglenoid development. These flagellates were found to develop usually after rains or during intermittent showers experiencing comparatively higher temperatures. A temperature range of 27° – 39°C was observed to be favourable for their growth. Higher concentrations of oxidizable organic matter showed a direct relationship to euglenoid population in Sewage Pond. It is suggested that certain species of Euglenineae, which very often developed in the polluted waters of Sewage Pond, could be used as biological indicators of pollution in the present investigation.

The data on which the paper is based were collected over a period of two years to study the ecology of algae in three freshwater ponds lying in the vicinity of Hyderabad — India. For the present it discusses only the temperature lags and ionic composition of the waters studied and brings forth the following:1.It is not the size of the body of water alone that controls the temperature lag in time and amplitude but the salinity of water and the density of its phytoplankton also alter the thermal behaviours.2.Ionic diagrams on the pattern proposed by Maucha, have been drawn.3.The ionic proportions of the waters studied differed considerably from those proposed for lakes in general by Rodhe (1949). Ionic composition of two of the ponds was Na > Ca > Mg > K; HCO3 > Cl > S04, but it was Ca > Na > Mg > K; HCO3 > C1 > S04, for the third.4.The ionic composition of the same body of water also differed from season to season and it was felt that the seasonal fluctuations which have secondary importance in lakes, become more significant in small freshwater bodies. Therefore, it is stressed that the ionic composition assessed from a limited number of observations may lead to wrong conclusions.

Investigations were carried out on dyes occurring in the green sulphur bacteria, Chlorobium limicolaNads. (Chlorobacteriaceae). The investigations concerned the absorption curves of extracts within wave-lengths of 250–700 mµ separated by means of circular and strip paper column chromatography. The fluorescent properties were also examined. The following solvents were used: 86% ethyl alcohol, benzene, petroleum ether, methyl alcohol, acetone and hexane. The fastness of the dyes extracted in 86% ethyl alcohol was tested over a period of 120 days. The results of the investigations showed that maximum absorption within red wave-length of extracts in 86% ethanol tends to approach the short wave-lengths after 120 days. The green sulphur bacteria, Chlorobium limicolaNads., contain a dye of the bacterioviridine type and a number of additional dyes of the carotenoid type. The investigations also showed that the dye is to a considerable extent, if not exclusively, bacterioviridine 650.

This paper deals with the standardisation of a suitable method to determine urease activity in bottom deposits of sewage stabilisation ponds and activated sludge units. Standard conditions were established; pH, incubation time, sample quantity, temperature, and the results are presented graphically. As the method is not dependent on ammonia distillation under vacuo, it is therefore suitable for serial analysis. Results from tests using this method can be used to determine the urea degrading efficiency of purification systems like stabilisation ponds and activated sludge systems treating urea containing effluents.

The present paper deals with the ecology of the River Moosi, Hyderabad (India). The data is extended over a period of two years with the collection of monthly samples. It deals mainly with the physico-chemical complexes operating in the unpolluted and polluted waters of the river at four stations, spread over a distance of about 25 km. The inter-relationships and fluctuations existing between the following factors have been discussed:i.Chloride and water current.ii.Nitrate, dissolved oxygen and free ammonia.iii.Nitrate and albuminoid ammonia.iv.Free ammonia and albuminoid ammonia.v.Dissolved oxygen, oxidizable organic matter and water temperature.vi.Total iron and pH.

1.The paper deals with seasonal changes in the composition and amount, by number and weight, of benthic organisms in riffles of three streams of different character (Shelligan Burn, River Almond, Allt dos Mhuicarain). Of the three streams the Shelligan Burn has the richest, and Allt dos Mhuicarain the poorest, chemical composition and surrounding vegetation. The River Almond has similar surroundings to Allt dos Mhuicarain but contains a much greater concentration of dissolved ions.2.The technique used to sample the bottom fauna is critically examined and compared with that using the Surber sampler.3.The mean standing stocks of bottom fauna, as dry weight per m2, were 2.88 g for the Shelligan Burn, 0.93 g for the River Almond and 0.70 g for Allt dos Mhuicarain. The greatest weight of bottom fauna in the Shelligan Burn occurred in May, and in the River Almond in April and May, when a high proportion of the organisms were of a large size prior to emergence. After their emergence the numbers of animals fell by 1/4 but the weight of animals present fell by 1/2. The largest numbers of animals in the Shelligan Burn occurred in July and February.4.The animals collected from the three streams were separated into 67 taxonomic categories, 37 of which were species. Fifty-three categories were represented in the Shelligan Burn, 45 in the River Almond and 49 in Allt dos Mhuicarain. Thirty-four categories, of which 17 were species, were common to all three streams.The fauna of the River Almond was similar in composition but quantitatively less than that of the Shelligan Burn. Allt dos Mhuicarain usually had less dense populations of the species present in the Shelligan Burn and River Almond. Some differences between the faunas of the streams can be attributed to differences in the chemical composition of the streams and special features of Allt dos Mhuicarain.5.Details of the seasonal changes in the numbers ofLeuctra inermis, Amphinemura sulcicollis, Isoperla grammatica, Ephemerella ignita andRhithrogena semicolorata caught in the three streams, and the seasonal changes in their biomass and size-frequency distribution in the Shelligan Burn are given. The sampling programme extended over three winters of differing severity, but no differences were found in the sizes attained in mid-February each year, by species of bottom fauna usually considered to grow during the winter months.6.Riffle stretches make up the greatest part of the three streams examined, but there are pools of slower flowing water and, in the Shelligan Burn, they constitute about 10% of the surface area. Riffles and pools of the Shelligan Burn were sampled in April and September. The riffles contained a higher numerical density of bottom fauna than the pools in the spring and in the autumn. There was no significant difference in the biomass densities of the bottom fauna in the two habitats.Leuctra spp. andBaetis spp. were several times more common in the riffles than in the pools.Ecdyonurus spp. were found in greater concentration in the pools than in the riffles in April, but were more concentrated in the riffles in September. The heavier, burrowing species such asDicranota spp., other Tipulidae andEiseniella spp. were more densely distributed in the pools than in the riffles.Chloroperla torrentium occurred in equal densities in the riffles and pools.

1.In Britain and certain other parts of western Europe, freshwater localities may contain only A. aquaticus, or only A. meridianus, or both species of Asellus, or Asellus may be absent from apparently similar localities. The present paper records the results of certain investigations which formed part of a programme of research designed to elucidate the causative factors of this pattern of local distribution.2.An investigation of the main physical characteristics, of the associated macro-flora and fauna, and of the chemical compositions of localities containing only A. aquaticus, only A. meridianus, or both species of Asellus did not reveal any major differences between these three types of locality. There was an indication, however, that there is a correlation between the occurrence of the genus and the concentration of calcium and of total dissolved salts.3.The results of investigations of the food, microhabitat, vertical distribution and tolerances to high temperatures, to low concentrations of oxygen and to dessication of the two species are recorded, and the work of previous authors upon these subjects is summarized. From a consideration of both the present and previous work, there do not appear to be any major specific differences.4.It is suggested that A. aquaticus and A. meridianus can be considered as occupying similar ecological niches.

1.The present paper concerns the studies of the plankton rotifers of Japanese inland waters. For this purpose, the writer examined more than 1500 plankton samples from more than 200 localities which are distributed in almost all parts of Japan. They contained, though plankton samples, not a few number of creeping and sessil rotifers as temporal plankters.2.With the addition of previous records, the number of Rotatorian species of Japan has become 186, with 28 varieties and forms, which belong to 4 orders, 13 families and 45 genera. They are enlisted in table III.3.Japan is conveniently divided into 9 districts. The number of species recorded from each district is as follows: — 1) Hokkaidô, 68 species; 2) the north eastern district, 72 species; 3) the central mountainous district, 122 species; 4) the eastern Pacific coast district, 60 species; 5) the central district, 158 species; 6) the southern Pacific coast district (incl. Inland sea coast), 41 species; 7) the north eastern Japan Sea coast district, 31 species; 8) the western Japan Sea coast district, 25 species; 9) the western district, 38 species.4.Some species noteworthy from various viewpoints are described. As the majority of plankton rotifers are of universal distribution, they are commonly found everywhere. So far as the rare and unusual species are concerned, the creeping rotifers have become the main subject of study. Among the euplanktic rotifers, only a few species are mentioned to be rare in Japan, namely, Conochiloides coenobasis, Brachionus angularis var. chelonis, and Keratella javana.5.Those which are originated either in the boreal or in the austral region are noted. Most of the rotatorian species are cosmopolitan, and they may be found, with only a few exceptions, at any longitude, if the environmental conditions are suitable. Accordingly, when the problems toward the distribution are considered, either the latitude or altitude is of more interest than the longitude is. In Japan, the southern boundaries of boreal species could be clearly observed, while the northern boundaries of austral elements were comparatively vague.6.So far as the widely distributed rotifers are concerned, there can be seen a tendency that the wider the distribution area, the larger the occurrence rate of pelagic species.7.The samples obtained from brackish waters were not numerous. In the present study, Brachionus plicatilis, Keratella cruciformis var. eichwaldi, and Pedalia fennica were pointed out as the representative haline rotifers.8.Some rotifers are well-known for their morphological variations. Above all, the following species have very ample variability in morphlogical aspects; i.e., Brachionus calyciflorus, Brachionus quadridentatus, Keratella quadrata, Keratella valga and Keratella cochlearis. The last mentioned species are of most interest with respect to the difference of both the seasons and the localities.9.The annual succession of plankton rotifers was observed at the southern basin of Lake Biwa-ko. The average changes of the important species examined during they from 1927 to 1937 were figured in the diagram.

The sulphur contents of the muds, water and vegetation at the northern end of Lake Victoria have been determined. Contrary to previous assumptions it was found that the sulphur in the bottom deposits is principally in the form of organic compounds and not as sulphides. Evidence is presented which suggests that the muds are in an aerated condition. The water of the lake contains extremely small amounts of sulphur and receives a negligible quantity of this element from the rain. The soils of the islands in the lake are rocky and well-leached of sulphur except where patches of forest conserve it. Certain peculiarities were noted in the behaviour of the muds and these are to be discussed in a future paper.

1.The paper presents the results of an investigation of the attached algal flora, as estimated by the growths on slides, of the slow sand filter-beds of the Whittle Dene Waterworks, Northumberland.2.The flora consists largely of filamentous and attached diatoms and Chaetophoraceae and shows marked seasonal differences in composition and abundance. Then community is compared with that of rivers.3.The factors influencing seasonal differences, colonisation, and succession are examined.4.Differences in the attached flora of beds which have been in operation for different lengths of time are considered in relation to the aquatic fauna.

A detailed account of the seasonal changes in vegetational cover, rate of biomass change and production of E. crassipes, growing under natural conditions in a perennial lake (‘Ramgarh’) of Gorakhpur (U.P.) India, is given in the present paper. The observations indicate that: a.The maximum biomass is found in mid-winter months after the maximum flowering period of the plant is over and the maximum cover in the post-winter months succeeding the maximum biomass period.b.The annual net production (excluding all losses caused either by respiration or by biotic interferences) is 103.0 g organic matter/m2.c.The maximum rate of biomass change is found as 3.8 g organic matter/m2.

In this paper records of Trichoptera in literature dealing with the standing waters of Africa south of the Zambezi, and from the relevant collections of material, are brought together and compared with those from elsewhere in the Ethiopian Region. The Trichopterous fauna of different types of standing waters in Southern Africa is described, and reasons for the lack of variety in the fauna are suggested. One of the main restrictive factors in their distribution appears to be the hydrogen ion concentration in the water, or some other factor controlled by it.

The paper deals with the periodicity of algal populations at four different stations of the River Moosi observed over a period of two years and the influence of the various physico-chemical factors on different algal groups. The data can be summarised as given below:1.The algae as a whole reach their maximum during winter (December–January) and touch minimum during the rainy season (September–November). The rate of the water current is more or less inversely proportional to the total number of algae at all the stations.2.High water temperatures seem to accelerate the growth and multiplication of Chlorococcales. High concentration of nitrite and low dissolved oxygen (at station 4) appear to be unfavourable for the development of this group.3.Desmids, which are more in number only at stations 1 and 2, are favoured by high summer temperatures and total solids.4.Diatoms, which form the main bulk of algal populations at all the stations, attain their maxima in winter (December or January) and minimum during Summer (May) and rainy season (September to November). These algae show an inverse relationship with temperature. The fluctuations in the silicates, nitrates and phosphates seem to show an inverse correlation with diatom periodicity. Diatoms are also favoured by higher concentrations of oxygen in the water.It has been emphasized that higher concentrations of dissolved oxygen in water lead to the formation of more nitrates and which in turn help in the production of larger number of these algae.5.Blue-green algae attain their maximum during the summer months and become rare in winter and rainy seasons. These show a direct correlation with the oxidizable organic matter and water temperature and an inverse relationship with dissolved oxygen.6.Euglenoid flagellates, like the blue-greens, are more during summer but with an optimum temperature of 28\dg\2–31.5\dgC. High summer temperatures seem to be unfavourable for their development. pH of water shows an inverse relationship in the periodicity of these algae whereas the total iron content goes almost hand in hand with these flagellates.

In the preceding paper, a revision of the species of the genusThienemanniolaKiefferis presented. The speciesTh. longipennisKiefferandTh. brevitarsisKiefferare declared to be synonymous toTh. ploenensisKieffer. All three stages of the metamorphosis ofTh. ploenensisare described and figured; ecological notes are also given. The speciesCorynocera ambiguaZetterstedtandCorynocera oliveriLindebergare briefly characterized and figured. Finally, the systematical classification of the generaCorynoceraandThienemanniolainto the familyChironomidaeand the degree of relationship between the generaCorynoceraandThienemanniolaare discussed.

This paper describes the diatom flora of the Grand River, Ontario, Canada. Samples were collected systematically from the river over a period of several years at tweleve stations. The diatom flora of the river is typical of temperate alkaline rivers. The flora is rich in species and variaties, and is similar to that from many parts from North Eastern United States. A total of 273 taxa of diatoms were identified. There is a tendency for the number of species per sample to increase downstream. The flora of the estuary in characteristic with a great variety of taxa occuring in small numbers. Most of the species are alkaliphilous and indifferent in the halolian spectra.

Taxonomy and ecology of Testacea in samples from Sphagnum and from sediments of a pool, some springs and small waters collected near Büschelbach (Bieber/Spessart, Germany) were studied. The results are explained in the present paper.

Investigations on the Rotifers of the brackish waters of the Lorraine (Moselle dept., France)1.The present paper is the result of the study of 80 samples collected between May 1st and August 10th 1965 in various brackish waters of eastern Lorraine (Moselle dept., France), by J. Duvigneaud, botanist, author of a comprehensive study of the halophile flora and vegetation of that region.2.Salt contained in the waters of the region studied is of geological origin. It is found in places where triassic layers touch the surface, e.g. in valley-bottoms or as a result of borings made for the needs of local industries. These salts are chiefly composed of chlorides, especially sodium chloride.3.The chlorinity of the waters studied varies quite considerably since in some places there is fresh water, while others are oligo-, meso-, poly- and even hyperhaline. A total of 35 Rotifer species have been identified, besides a number of illoricate forms, that became unrecognisable owing to formaline contraction.4.The Rotifer fauna of our milieu was compared with those of a number of Central-european regions with brackish waters of geological origin, that have been studied by various authors. The results showed that all the faunas implied possess a common structure. The latter consists of the following elements:

The phytoplankton of four ponds in the lower Piedmont and upper Coastal Plain of North Carolina was studied to find a possible correlation between bound phosphorus plankton numbers. No correlation was apparent therefore this paper reports a detailed study in relation to other habitat factors. The ponds are all shallow (2 m.). The Piedmont ponds are high in colloidal clay while the Coastal Plain ponds are much lower. The pH ranged around 7.0 except for one Coastal Plain pond which remained close to pH 6.4. Water temperature ranged from 30° C in June to 23° C near the end of August. Phytoplankton numbers were determined by the standard Sedgwick-Rafter method. Populations were low except for brief pulses. One Coastal Plain pond was typical of a fertilized pond and had several tremendous blooms of blue-green algae. The others supported a seemingly typical Caledonian flora, rich in species but low in number of individual organisms. There was no clear correlation between phytoplankton populations and any habitat factor except pH. This correlation is probably not direct but only an indication of water quality.

This paper records the results of a faunistic survey of the mountain streams of the Barberton area of the Eastern Transvaal. Sampling was carried out in five different biotopes; cascades, sprayed flanking regions, stickles, backwaters and pools. Netting of the adults and imagos and breeding out of the larvae of Chironomidae, Odonata and Ephemeroptera was done. The faunal affinities were assessed by a comparison of the mayfly fauna of this area with that reported in other surveys conducted in Africa.

The paper is based on a two-year study of the distribution of phytoplankton in three freshwater, polluted and unpolluted ponds of Hyderabad, India. The distribution of several groups of algae likeVolvocales, Chlorococcales, Desmids, Diatoms, Dinoflagellates, blue-greens andEuglenineae exhibited interesting relationships to the physioo-chemical complexes of the ponds, and throws much light on the algal distribution in Indian waters. The discussion revolves around the yearly and overall averages of the ecological factors and the various groups of algae. Dissolved oxygen, oxidizable organic matter, free carbon dioxide, nitrates, phosphates, calcium and sulfides have been found to play a significant role. The fluctuations of certain ratios such as N : P : K, C/N, percent sodium, percent Cl + NO3 and Pearsall's basic ratio suggest distinctly important clues in the distribution of various groups of algae.

The paper discusses the distribution and periodicity of Volvocales, Chlorococcales, Desmids, Euglenineae and phytoplankton in general occurring in three freshwater ponds. It is observed that the polluted pond harboured densest phytoplankton population comprising of Volvocales, Chlorococcales, Myxophyceae and Euglenineae. Bluegreens were particularly abundant in alkaline waters (pH 8.69) which were rich in nitrates (12.58) and dissolved oxygen (5.5). The ponds harbouring diatoms and desmids were less polluted. It is emphasized that ecological behaviour of several species does not fall in harmony with the behaviour of the taxonomic group or class of which they are members. Therefore, attention was paid to the ecology of individual species as far as possible. In their seasonal fluctuations different algal groups were apparently favoured by the ecological conditions given below.

The paper gives a comparative account of the physico-chemical complexes of three freshwater ponds, differing substantially in organic pollution and biological populations. They were studied over a period of two years at the regular interval of 15 days. The results are summed up below.:1.Fluctuations in the pH of water were identical to those of carbonate content, which varied inversely with bicarbonates in all the ponds. Free ammonia influenced the pH appreciably in one pond while larger concentrations of phosphates had a buffering effect.2.Unusually high pH (9.4) was recorded in one of the ponds during the thick growths of Microcystis aeruginosaand Merismopedia minima, which possibly, on withdrawal of CO2from HCO3, released OH ions in the water.3.Free ammonia and albuminoid ammonia varied almost directly to each other in two ponds but converse was true for the third. Their relative proportions in water possibly depended on the bacterial activity.4.Appreciable quantities of nitrates were brought into the ponds with surface run-off. The days of high nitrate contents also coincided with those of low values for free ammonia.5.The pond which showed a bloom of Chlorella vulgaris, experienced biological destruction of nitrates.6.The pulses of phytoplankton were accompanied by the accumulation of oxidizable and nitrogenous organic matter in water. This indicated that quite large quantities of extracellular substances were liberated into it.7.Generally speaking, the concentrations of iron increased with the fall in pH of the water. The low concentration of this element was helpful in accelerating the decomposition of organic matter.8.The pulses of diatoms resulted in a decrease of silica in these waters.

The results of the limnological investigations of “Swetganga”, one of the thermal springs of Bakreswar, West Bengal, India, have formed the basis of this paper. The samples of water were collected eleven times from the month of September '67 to October '68 at regular intervals for analysis. The physical conditions like depth, temperature and chemical factors like pH, free carbon dioxide, phenolphthalein alkalinity, total alkalinity, total hardness, chloride, nitrite, nitrate, phosphate, silicate and dissolved oxygen were determined. A qualitative and quantitative analysis of plankton was also made. The water of the Kund was found to be distinctly alkaline on all occasions. Since free carbon dioxide was absent in all samples, phenolphthalein alkalinity was always recorded in appreciable quantities. The lower values of chloride were noted only during the monsoon months due to the dilution of water by the rain. The silicate content showed erratic fluctuations. Large amounts of phosphate were always present in the Kund. The absence of nitrite and traces of nitrate throughout, is a characteristic feature of this thermal spring. An attempt has been made, whenever possible, to attribute the reason of the changes and also to correlate the plankton blooms with the chemical factors. The coefficient of correlation between total alkalinity and phytoplankton (−0.529) indicates a negative correlation, significant at the 10 per cent level. No significant relation between phytoplankton and pH values (r = 0.183) has been observed. An apparent inverse relation between dissolved oxygen and phytoplankton has been noted. A list of phytoplankton and zooplankton has been incorporated. Total phytoplankton varied between 8.91 per cent and 100 per cent and the zooplankton between nil and 91.08 per cent of the total plankton bulk.

In this paper the Diatomflora, based on some collections from Lonavla hill-station, is systematically accounted with some field notes.

The paper deals with the distribution of certain classes of algae in two fishponds of Hyderabad — India. Amongst all the ecological factors discussed in this regard, it is emphasized that Pearsall's basic ratio of water (Na + K/Ca + Mg) plays a distinctly important role. It is concluded that (a) if the basic ratio fluctuates between .027 and 1.2, Diatoms dominate the algal population, (b) if it works out between 1.2 and 2.0, green algae and Diatoms contribute more or less equal percentages to the bulk of phytoplankton and (c) if it is higher than 2.0, there is very little chance of Diatoms becoming dominant as the green algae, particularly Chlorococcales and Desmids, are in abundance. It is also noted that very high values of the basic ratio (3.7–5.5) do not help in increasing the percentage of green algae any further in the population.

This paper is the second of a series covering the crustose corallines of the Gulf of Maine. Information on anatomy, cytology and the development of the reproductive structures is presented to show that Clathromorphum is a genus distinct from both Phymatolithon and the branching members of Lithothamnium. Also, for the two species of this genus present in the region, reproductive cycles and geographic and bathymetric distributions are presented and discussed.

The paper is based on the two-year data on the monthly fluctuations of the various physico-chemical complexes operating in two fish breeding ponds of Husain Sagar Fish Farm, Hyderabad, India. It includes discussion on the inter-relationships of the following sets of factors.