The phytoplankton of Koprinka Reservoir (Central Bulgaria): species composition and dynamics

The aim of the study was to determine the species composition and dynamics of the phytoplankton community of Koprinka reservoir. We have identified a total of 109 taxa assigned to 6 divisions including Chlorophyta (37), Ochrophyta (26), Cyanoprokaryota (22), Euglenophyta (11), Streptophyta (11) and Pyrrhophyta (2). The highest phytoplankton biomass (PhB) and numbers (PhN) and the lowest species richness were detected in September. In October with the decrease of the PhB the species diversity has increased. The highest species richness was observed at station 3, situated in the riverine area, with the phytoplankton abundance being significantly higher compared to the other two stations. The species Hariotina polychorda dominated in the water samples in the summer at all stations. In the early autumn, a bloom of the potentially toxic species Microcystis wesenbergii was detected, which is an indicator for eutrophication process in the reservoir. Cluster analysis (CA) based on the phytoplankton composition isolated the samples from each sampling periods in a separate water cluster, characterized by significant spatial heterogeneity. The phytoplankton species composition, and the values for biomass, and chlorophyll a are evident for the eutrophic state of the reservoir

Genetic Disease Patterns in Japan: A Review

Comprehensive genetic studies in which the genetic structure of a population is considered against the background of ecological factors, including environmental and social variables, often supply valuable information for the solution of a number of problems in human biology, including reproductive compensation and inbreeding depression. In the first section of this paper we consider the incidence of genetic diseases in Japan in reference to other populations. Some of the genetic disorders found elsewhere do not occur or are of lower frequencies in Japan. On the other hand, a number of genetic diseases occur at higher than usual frequencies, leading to an incidence of genetic disease of the order of about 1 per 100 in newborn Japanese. We next review the studies of consanguinity in Japan and report evidence of very high levels, ranging from 8.6% to 58.0%, for villages during the early part of the twentieth century. The rates are declining rapidly for the country but, because of traditional social values, inbreeding rates remain significant in many small villages. In the final section we consider the probable trends in the frequency of inbreeding on a worldwide basis and point out that frequencies of certain genetic diseases are likely to remain high and even increase in some societies because of various socially prescribed mating patterns