“… a small bottom sample … from the depth of 33 meters taken near the Olkhon Gate of Baikal Lake on July 29th 1916. I have examined about a hundred of microscopic slides from this place and have taken great care to identify and illustrate the forms… The result was unexpected; I have identified 304 species, varieties and forms, among which 148 are new” (Boris V. Skvortzow 1937)
I had to wait a bit before I got my hands on the recently published Lake Baikal: Hotspot of Endemic Diatoms I. In this impressive body of work, Maxim Kulikovskiy and colleagues, document several hundred species of diatoms from benthic communities around the lake. In the 600 or so pages, the authors describe and illustrate 222 species and 10 genera as new to science! Moreover, they report as many as 170 taxonomic entities yet to be identified or described. If you are not a diatomist, or better a diatom taxonomist, you would probably be surprised when I say that I wasn’t instantly amazed by these numbers. After all, this is the norm for most volumes of Iconographia Diatomologica. For this I blame the extremely fluid state that diatom taxonomy enjoys/suffers from over the past two-three decades. New species are being described left and right, especially from exotic, previously un(der)studied areas, and often without observations of type material or explicit statements of species concept (guilty my self).
After a bit more reading however, some excitement about this book started to creep in. The first instance of ‘wow’ came when the authors mentioned that all newly described species come from only 27 genera! I know, first hand, that benthic diatoms in ancient lakes are very diverse, but 222 new species from just 27 genera? That was somewhat unexpected. What should we expect when more genera are worked out? Then I flipped through and stumbled upon my second ‘cool’ moment: these results are based on observations of just 28 samples; mainly from the Ushkaniy Islands in the northern basin. So all this diversity is found in a fairly small number of samples coming from a more or less limited area in the lake. Again, the question begs, what will happen when we scale to the entire lake?
What made me really appreciate this book was the realization that some of the samples used are original material collected by Skvortzow and Skabitschewsky. Kulikovskiy and colleagues managed to dig out old material and at least had the opportunity to compare their observations to the specimens that the pioneering researchers would have been looking at! I fully understand that not all type material for Lake Baikal is available, and that each newly described taxon cannot be compared with the rigor we’d like to descriptions and line drawings from 70-80 years ago. However, the information presented in ‘Lake Baikal: Hotspot of Endemic Diatoms’ must represent a better synthesis of diatom taxonomy than it would have been without Skvortzow’s and Skabitschewsky’s material. Kudos, Maxim et al.!
Kulikovskiy and colleagues hazard a guess that Lake Baikal harbors up to 1500 diatom species. Even if the real (probably unknowable) number of species is ten times smaller, the sheer variability of forms indicates how little we still know about Baikal’s biodiversity.