This paper presents a taxonomic and ecological study of Bacillariophyceae in the Paraná River (Argentina). Qualitative and quantitative monthly samples were taken in eight sampling stations, between 1976 and 1984. Cell counts were performed using the Utermöhl method (1958). Major physical and chemical characteristics of the stretch of river are described. Bacillariophyceae density is compared with total phytoplankton and major environmental variables (hydrometric level, transparency, temperature, pH, conductivity, dissolved oxygen and nutrients) in each sampling site. We present 145 taxa classified in 35 genera: 11 Centrales and 24 Pennales. Centrales were represented by 20 taxa (11%) and Aulacoseira granulata and its varieties numerically predominated in the phytoplankton in most of the studies. Pennales appeared in a lower density but in a higher specific richness, totaling 125 taxa (89%). All registered taxa are illustrated and both their geographic distribution and ecological preferences are provided.

This book presents the results of investigations on the planktonic diatom flora of the so-called High and Lower sections of the Parana River, made between 1976 and 1984. Unlike most other investigations on this river before, the authors identified the taxa on species (or variety) level.

The first part of the book is the list of the 145 found species with some words about their dimensions, geographical distribution and ecological preferences, supplemented with the authors' special observations in some cases. In the next part a drawing of each taxon can be found, indicating also the sizes.

The third part contains the ecological results: the mean values of the temperature, Secchi depth, conductivity, pH, Centrales-, Pennales- and total phytoplankton density at the different sampling stations; the course of hydrometric level, Secchi depth, Centrales-, Pennales density and Bacillariophyceae density relative to total phytoplankton; the found correlation and another species list indicating the occurrences at the 12 sampling sites. In my opinion the book might become a great help for hydrobiologists, algologists working on rivers, provides useful information on the collected diatoms and also on the main yearly trends of floods and low water periods, other ecological data and their effect on phytoplankton.

B. BESZTERI

Acta Botanica Hungarica 42, 1999/2000, p. 360