The material examined was taken from the Pyrenees in Spain. Almost 360 specimens were analyzed comparing with the specimens from Cuzco (Peru) and Taitong (Taiwan). The margins of the valve are almost parallel in the specimen s from the Pyrenees, while they are mostly convex in those from Cuzco and Taitong. Though the valves are mostly symmetry with respect to the raphe in the specimens from the Pyrenees, they are often asymmetry in those from Cuzco and Taitong. As to the arrangement of the striae at the both ends, it is radiate in the Pyrenees (ca.99%) and parallel in Taitong (ca.72%). Three types, radiate, parallel and irregular are observed with almost the same frequency (ca.32 %,36 % and 25%respectively) in the samples from Cuzco. The breadth of a valve in the Pyrenees is the narrowest among the three places. The specimens from Taitong have the widest valves. As to the density of the striae, similar density is observed in the specimens from Taitong and Cuzco and denser striae are observed in those from the Pyrenees.
Samples of attached diatoms were taken from the flat upper surfaces of submerged stones in the Rio Negro, a tributary of the Amazon River, at Ponta da Praia (Km 18), opposite the Tropical Hotel, Manaus, Amazonas, Brazil, on August 8,1986. The samples were examined with a light microscope and each taxon was photographed, illustrated and measured for identification.19 taxa from 12 genera are recorded, distributed as follows; one species of genus Actinella (A. brasiliensis GRUN. ), one species of genus Anomoeoneis (A. exilis (KÜTZ. ) Cleve f. lanceolata A. MAYER, ) two species of genus Cymbella (C. amphicephala NAEG. and C. ventricosa KÜTZ. ), five taxa of genus Eunotia (E. diodon EHR., E. lunaris (EHR. ) GRUN., E. valida HUST,. E. fallax A. CLEVE var. gracilima KRASSKE and E. pectinalis (Dillw. ? KÜTZ. ) Rabenh. var. minor (KÜTZ. ) RABENH.), one species of Cyclotella (Cyclotella sp. ), one species of Fragilaria (F. constricta EHR. ), two taxa of Frustulia(F. rhomboides (RABENH). DE TONI f. saxonica and f. undulata HUST. ), (RABENH), one species of Gomphonema (G. subclavatum EHR. ?), two species of Pinnularia (P. subcapitata GREG. and P. hemiptera RABENH. ), one species of Navicula (N. cryptotenella LANGE-BERTAL ? ), one species of Nitzschia (N. palea (KÜTZ. ) W. SMITH), and one species of Synedra (S. rumpens KÜTZ. var. scotica GRUNT. ?). Eunotia was the best represented genus in number of taxa identified, while Actinella, Cyclotella, Synedra, Fragillaria, Nitzschia, Anomoeoneis and Gomphonema were the least represented of all.
The pennate diatom Neosynedra provincialis bloomed prominently on the surface of plastic plates which were placed in a seawater tank to grow diatoms for the primary food of abalone larvae in 1982. The electron micrographs are shown to inform the morphological features. Propagation of this diatom in the maricultural tank might be caused by excessive aeration of seawater flowing in the tank. The growth of threadlike colonies of this diatom looked unfavorable for abalone larvae, because the individuals living on the plates tended to get out of their feeding beds. Localities on the Japanese coast where N. provincialis has been found are noted.
The preset condition of water pollution in Lake Biwa was investigated based on the attached diatom assemblages in 1988. In the investigation, samples were collected from 31 sites along the shore (22 sites in Northern basin,9 sites in Southern basin),12 sites on the traverse line of the lake (9 sites in Northern basin,3 sites in Southern basin). Among dia tom taxa occurred in those samples,164 taxa belonging to 29 genera which identified were listed up and 231 photographs with 2000 magnification on 100 taxa were shown in 7 plates. Ecological information on the water pollution of this lake will be reported in other paper.
The common saprophilous and saproxenous species groups in the flowing and standing waters were obtained based on mathematical principle. The number of taxa belonging to the former is 29, and that to latter is 58. DAIpo 50 mark is a common boundary which distinguishe d between oligosaprobic and mesosaprobic zone in the flowing and standing waters. Occurring of such a diatom assemblages as saproph ilous taxon becomes dominant species, is limited in the water quality zone with below 50 in DAIpo marks, and that of saproxenous species becomes dominants, is limited in where with over 50in DAIpo marks, in both flowing and standing waters. Saprophilous and saproxenous species do not usually coexist with each other as dominant or subdominant species. Shannon's diversity index vary describing a parabola with increase of pollution degree. And the variational pattern of the index shows a symmetry between the right and left halves separated by the boundary of which DAIpo marks is 50.
The drilling surveys of lake deposits were done at the two sites in Lake Tega in order to clarify the environmental changes of the lake during the Late Holocene. Five zones of diatom assemblages are recognized in the Holocene lake deposits. The following changes of lake environments are presumed by the successive change of diatom assemblages. Lake Tega had been a brackish lagoon before the salinity of lake water became variable in 1700-1850y. AD. This salinity change was caused presumably by the artificial change of the course of the River Tone. The fresh water environment has continued since about 1850y. AD.
Diatom samples collected from natural habitats contain usually with both alive and dead cells. Comparisons of the data obtained from the parmanent slides made with stained materials and with cleaned materials indicated significant difference with regard to community structure, i. e. total number of species and relative frequency of species. The difference was marked in the case of the sample contained many dead cells and almost of them were allochthonous in origin. Parmanent slides of cleaned materials have no information about the state of cells at the time of sampling and therefore the data obtained from the slides will lead us to erroneous conclusion. In the parmanent slides made with the materials which stained with Mayer's Hematoxylin and mounted with Pleurax mounting medium, alive and dead cells can be distinguished and thereby the data obtained from the slides will lead us to correct conclusion.
The Ca-content of the inlandwaters of Japan is in general so poor that it is merely about one tenth of that of european and american inland-waters. But, around the limestone regions of our native land, there are a few inlandwaters which contain a considerable amount of calcium. It is to be regretted that the diatom vegetation of those waters is hitherto completely unknown. The River Seri (Seri-kawa ), located in the eastern si de of Lake Biwa, Shiga Prefecture, was chosen for our investigation. Its total length along the axis is about 19km. It takes its souce in the midslope of Mt. Ryozen (1084m above the sea), which stands nearly on the prefectural boundary between Shia and Gifu, a nd is made up of limestone and schalstein. Its water is rich in lime (Ca 30-43mg/1), alkaline (pH 8.1-8.4), and has the pretty high electric conductivity (180-214 μs /cm). The whole course of the river receives no appreciable pollutants, although the river passes through the urban district of Hikone-City in its lower course and flows into Lake Biwa -(the First Section). The diatom flora of the River S eri is composed of 34 forms belonging to 20 genera, as shown in the Second Section. The diatom communities of seven selected stations are as described in the Third Section.
I surveyed the diatom assmblages in the River Asa-kawa from November 1986to September 1987, and found several characteristics of biological indices based on diatom assemblages. Indices calculated from relative frequency of species show higher correlation to EC and COD than indices calculated from number of species in an assemblage. The former have a tendency to correspond to average water conditions, and, in contrast, the latter have an another tendency to suggest water conditions which appear most frequently. When we want to use these indices we have to know the list of ecological species groups. Several lists have been made. But there are some differences between these lists and it may affect the indices. So we should consider the criterion of selecting indicator species. In this study, “SI” (PANTLE & BUCK,1955) using the list proposed by KOBAYYASHI et al. (1985)shows the highest correlation to EC and COD in all biological indices. But the reason of this result seems to be that the River Asa-Kawa doesn't have neither highly polluted nor extremely clean -parts, and if we want to survey waters including such extreme conditions, we had better use “DAIpo” proposed by WATANABE et al. (1986).
A new method for paleoenvironmental reconstruction was presented to analyze paleoecology of fossil diatom assemblages. Similarities between fossil assemblages and present communities were measured to find out same community in a present environment. The Jaccard's coefficient was utilized as similarity index in this paper. The fossil assemblages from the Holocene sediments deposited after the maximum stage of the Jomon (Holocene) transgression were examined to reconstruct paleoenvironments on the basis of similarities between fossil assemblages and many present communities in various environments. As a result, similar present com munities to fossil assemblages could be identified and it was clarified that the vertical succession of fossil assemblages corresponded to spacial one of present communities from marine to limnological conditions.