Ecological analyses using multivariate methods and some examples of their application to diatomological studies were reviewed in the present paper. Multivariate analysis has become popular in ecological studies of communities, including diatom communities and assemblages. Multivariate analysis comprises a large number of methods, and each of them has its own advantages and disadvantages. Therefore, it is concluded that there is no right way of applying multivariate analysis to ecological data. Nevertheless, multivariate analysis is useful to detect ecological information such as species-to-environment association, species-to-species association, and configulation of samples.
The effect of extracellular products in each growth stage of Porphyra tenera for the growth of Licmophora sp. was examined. The unialgal c ulture was incubated at 15°C in 12: 12h light-dark cycle and illuminatedb y cool white fluorescent lamps at 4,000-5,000 lux. The, results are as follows. 1) The growth was markedly promoted by the filtrate obtaine d from 0-31 days culture. 2) The exponential phase of the diatom was elongated by the filtrate from 31-5 5 days culture. 3 ) The mixed filtrates after 55-67 days (matured) were of no effect to the growth of Licmophora sp.
When we decide only the first and second taxa in their relative abundance in an attached diatom assemblage, we can obtain the DAlpo (diatom assemblage index to organic water pollution)approximate value and the saprobic level in a saprobic system of the investigated site from proposed tables. We think the method will receive wide application as a simple biological simulating method for organic water pollution, and also for paleolimnology. The diatom assemblages in which the predominating taxo n belongs to Achnanthes are usually representative ones in clean water such as xenosaprobic and oligosaprobic area with over 50 in DAlpo value. However, Achnanthes exigua and A. minutissima var. saprophila occurred respectively in polluted waters from a-mesosaprobic to polysaprobic as the most dominant taxon. The assemblage in which the predominating taxon belongs to Anomoeoneis appeared in α-oligosaprobic standing waters, to Aulacoseira in both δ-mesosaprobic flowing and standing waters, and to Melosira in oligosaprobic flowing waters.
Ecological characteristics of the diatom assemblage in which the predominating taxon belongs to Cyclotella, Cymbella, Diatoma, Fragilaria, Gomphoneis or Gomphonema are the following. Cyclotella: They occur in oligosaprobic waters with 50-84 in DAIpo marks, when its second taxon is a saproxenous taxon. They also occur in polluted waters with less than 29 in DAIpo marks, when its second taxon is a saprophilous taxon. Cymbella, Diatoma and Gomphoneis: They occur in clean water with over 50 in DAIpo marks respectively. When the predominating taxon is Cymbella minuta var. minuta, C. sinuata var. sinuata or Gomphoneis quadripunctatum respectively, they are commonly found in clean flowing waters with over 70 in DAIpo marks. Fragilaria: The assemblages, in which the predominating taxon belonging to Fragilaria except F. construens var. veneta and F. pinnata var. lancettula, occur in clean standing waters with over 50 in DAIpo marks. F. vaucheriae var. capitellata occurs in very clean waters with over 70 in DAIpo marks as the predominating taxon. Gomphonema: The assemblages in which the predominating taxon is G. vibrio and its varieties occur in clean waters with over 50 in DAIpo marks. However, when G. angustatumorG. parvulum with its varieties is the most abundant respectively, it appears in polluted waters with less than 49 in DAIpo marks.
The assemblage in which the most abundant taxon belongs to Navicula appeared in 281 sites among 1287 sampling sites in flowing and standing waters. The number of the most abundant taxon belongs to Navicula and that of sites in where such the diatom assemblage occurred in each saprobic level are the following. From these facts, it can be seen that the taxa which belong to Navicula occur so frequently as the dominating taxon in attached diatom assemblage, and in the polluted waters than the clean waters. The dominating taxa with much frequency of occurrence are the following ten taxa; Navicula atomus var. atomus, N. gregaria, N. minima var. minima, N. mutica var. mutica, N. mutica var. goeppertiana, N. mutica var. stigma, N. mutica var. ventricosa, N. pelliculosa, N. seminulum var. seminulum, N. subminuscula.
Ecological chracteristics of the diatom assemblage in which the predominating taxon belongs to Nitzschia, Pinnularia, Surirellaand Synedra are the following. Nitzschia: Thirteen taxa belong to Nitzschia occurr ed as the predominating taxon in 391 sites (30%) among 1287 sampling sites. Almost all the taxa occur in oligosaprobic and β-mesosaprobic waters with 30-84 in DAIpo marks, however, Nitzschia palea is one of the few saprophilous taxa among them and occur frequently in polluted waters with less than 29 in DAlpo marks. Pinnularia: Pinnularia brauniivar. amphicephala is generally known as an acido biontict axon, moreover, this is a typical saprophilous taxon. Surirella: Two taxa belong to Surirella occurred as the predominating taxon in slightly polluted flowing sites with 30-51 in DAIpo marks. Synedra: The diatom assemblage in which the predominating taxon belongs to Synedra has a tendency of occurring in clean waters. Among the seven taxa appeared as the predominating taxon, Synedra inaequalis and S. ulna var. ulna occurred in xenosaprobic and β-mesosaprobic flowing waters respectively, S. acus, S. delicatissima var. deticatissima, S. rumpens var. familiaris, S. rumpens var. fragilarioides and S. amphicephala in oligosaprobic standing waters.
Yungchun Dam Reservoir is located in the east about 80 km away to Taegu City in Korea. Collections for diatom analyses were made, at eight different stations including tributaries on July 31in 1990. A total of 125 taxa, distributed among 30 genera, were found. These taxa are described together with the distribution in the area studied. Hannaea arcus (Ehr. ) Patr. var. subarcus (Iwah. ) Lee is described as a new combination. In 11 plates, all taxa are depicted by microphotographs. In two additional plates, the morphological details of some taxa are shown by SEM photographs.
An individual of Climaconeis inflexa was obtained from Sagami Bay. It increased the number of cells by laboratory cultivation in enriched seawater in March 1985. This diatom also showed circular movement on agar flat in Petri dishes. Another individual of this diatom was found in a fixed population collected from Hachijo Island, the Izu Islands of Tokyo Metropolis, in August 1986. The number of striae in valve face of those specimens observed with TEM was 32-34 in 10 pm, which is far greater than the description by Cox (1982).
Imparvalvia, a new genus of araphid diatoms, is described from the Miocene marine sediments of the Koitoi Formation, Hokkaido, Japan. This monotypic genus is represented by Imparvalvia laevigata sp. nov., of linear-lanceolate form, which has a heterovalvar frustule consisting of a simple hyaline epivalve and more intricate-structural hypovalve furnished with the paraseptum. There is no areolation excluding several pores on the frustule. The genus should be placed in a new family, named Imparvalviaceae, due to its highly distinctive nature.