Reavie and Smol present the first detailed description of the diatom flora of the St. Lawrence River, Canada. They provide light micrographs of 227 diatom taxa from 35 genera, recorded in 299 samples from the freshwater portion of the St. Lawrence River, between Kingston and Quebec City.
Diatoms were identified in both plankton samples and periphytic collections (rocks, macrophytes, filamentous green algae) as well as sediment core samples. High species diversity is observed so that the discussion was limited to the more common taxa (that is taxa that occured in at least three samples, or had a relative abundance of more than 1% in one sample). The taxonomic and iconographic sections of this book include descriptions and illustrations of the taxa encountered, as well as autecological information.
These data may assist future biomonitoring and paleolimnological study efforts.

The object of this book is the first detailed description of the diatom flora of the freshwater section of the St. Lawrence River.

The St. Lawrence River is the outflow of the Laurentian Great Lakes complex, which is the largest freshwater reservoir of the world. The river is employed in many ways: as a drinking- and industrial water and has recreational and transportation usage as well. In consequence of these it has suffered many and not even positive changes in respect of the water quality.

An autecological database was developed for the freshwater section of the river and this book contains the diatom species from that database.

Sampling processes were performed on many points alongside the river. Living material was gained from plankton and periphyton of rocks, Cladophora-filaments and different macrophytes. Fossil material was gathered from the river bottom, too.

All in all, it is a very exhaustive examination of the freshwater diatom flora of the St. Lawrence River and offers possibilities to interesting comparisons, for example to compare the substrate preference of different taxa and the similarities and dissimilarities in the living and fossil diatom flora.

We have to remark, that not all taxa, but only the more common ones are included in this book, namely 227 taxa from 35 genera. A full dataset is available elsewhere. One can find light-micrographs from all diatom species, in 30 plates and also notes on the autecology of many species.

Three figures make it easier to skim through the sampling points and there are also two tables and a very accurate list of species, which help the orientation among the data.

Summarising, this beautifully prepared edition of high level is an exact and well-arranged one, which can be an enormous help for diatomists, phycologists dealing with the St. Lawrence River, or the diatom flora of large rivers, but also useful for the others, while enlarges the general knowledge on the spread and autecology of diatoms.

K. SZABO

Acta Botanica Hungarica 43 (1-2) 2001, p. 224-225