Dinoflagellates are important primary producers, symbionts and, at the same time, heterotrophic consumers and parasites. The species composition in benthic habitats is quite distinct from planktonic habitats. Our understanding of benthic dinoflagellate biodiversity, biogeography, toxicology and ecology has improved but is still rudimentary. Benthic harmful algal blooms have attracted increasing interest because of the impact of ciguatera poisoning, the most important food-borne disease of non-bacterial origin worldwide, which is caused by benthic dinoflagellate species. Ciguatera ­poisoning appears to have increased worldwide in recent years.

This publication is an updated summary of the taxonomy of currently described taxa and includes morphological and molecular genetic information for species identification. It contains the most comprehensive review of benthic dinoflagellate toxins published so far. The book also describes methods of study, discusses phylogenetics and evolution, and highlights their scientific relevance as well as the health and economic impacts of benthic dinoflagellates for society.

This book is a fundamental contribution to improve the monitoring of benthic dinoflagellates worldwide: 242 species in 63 genera are presented, illustrated with more than 240 color images, about 250 electron micrographs and more than 330 drawings.

Of marine dinoflagellates, many studies have reported on ‘planktonic dinoflagellates’, species that occur in the water column. On the other hand, until the 1970–1980s, not many studies had focused on ‘benthic dinoflagellates’, which live in benthic environments, such as interstitial spaces of sediments/sands or surfaces of macroalgae, rocks and coral. Subsequent to the benthic dinoflagellate genus Gambierdiscus, now known to produce toxins responsible for ciguatera poisoning, being described in the late 1970s, taxonomic studies of toxic benthic dinoflagellates have increased worldwide. In recent decades, a number of spe- cies have been reported to produce toxins that cause food poisoning or pose human health hazards.

The second edition of the book ‘Marine benthic dinoflagellates’ has now been published in 2023. The first edition of this book was published in 2014. It introduced a comprehensive and systematic summary of the taxonomy and other aspects of marine benthic dinoflagellates, summarising 45 genera and 189 species of benthic dinoflagellates described as of 2014. The second edition has updated the status as of 2023, introducing 63 genera and 242 species. This rapid expansion in the number of genera and species demonstrates how much taxonomic research on benthic dinoflagellates has been conducted around the world in the past 9 years.

The second edition consists of six main chapters.
Chapter I,‘Background’, summarises the history and current status/ problems of the systematics of the benthic dinoflagellates.
Chapter II, ‘Materials & Methods’, describes experimental aspects of benthic dinoflagellate research, including sampling, microscopy, culturing and counting methods, molecular detection and quantification methods, and toxicity/toxin analyses.
Chapter III, ‘Taxonomy’, comprising the main section of the book, provides a detailed taxonomic summary of the currently described species with beautiful optical/electron micrographs and illustrations along with references. In addition, as discussed in this second edition, because many cryptic species that cannot be distinguished by morphological characteristics alone have been reported in recent years, nucleotide sequence data, such as ribosomal DNA regions, have become essential for molecular identification of these species. Accordingly, in the second edition, accession numbers for nucleotide sequences related to the type materials of each species have been newly added when available and useful.
Chapter IV, ‘Phylogeny and systematics’, contains a discussion of the phylogenetic position of each genus based on morphological characteristics and molecular phyloge- netic information.
Chapter V, ‘Toxins of benthic dinoflagellates and benthic harmful algal blooms’, provides currently available information on the toxin production and toxicity of each species and those references with tables.
Chapter VI, ‘Relevance for science and society’, summarises the status of benthic dinoflagellate research in two sections: basic research and health, social and economic research. The former section reports the evolution of dinoflagellates/chloroplasts/toxicity and related genes, as well as their use in nutritional supplements and natural products, whereas the latter section reports the impacts of the toxins and related food poisoning on human health and socioeconomic activity. Because an accurate classification and identification of each species and the development of monitoring methods based on the detailed taxonomy are necessary to accurately assess the scientific and social impacts caused by benthic dinoflagellates, it is expected that taxonomic studies on these microalgae will be actively continued.

I believe that this book will contribute greatly to improving observation skills especially for young researchers studying benthic dinoflagellates. I am one of those who have greatly benefited from the first edition. I read it very carefully and attempted to memorise the morphology of each taxon. As a result, my resolution of species identification has improved dramatically, and this has greatly helped me to identify spe- cies in field samples by microscopy.

Therefore, I recommend this book to all those who are beginning their research on benthic dinoflagellates, to those who have studied these microalgae and to many others involved in marine ecological research. Finally, I am grateful to Dr Mona Hoppenrath and the other authors of this book for the opportunity to write this book review.

The second edition of this book has been recently published by Senckenberg Gesellschaft für Naturforschung. It sum­ marizes the current knowledge on benthic dinoflagellates, providing a complete catalogue of known species: 242 species belonging to 63 genera, including sand-dwelling and epiphytic taxa. Most of them are illustrated with colour images, electron micrographs and drawings.

Detailed descriptions about morphological characteristics, plate pattern, known distribution, and comparisons with simi­lar species are provided for each species. Information on molecular sequences available, not included in the first edi­tion, can also be found. However, the book is not only a taxonomic manual for the identification of benthic dino­flagellate diversity. It contains additional chapters that provide a comprehensive overview of the state-of-the-art in different aspects of their biology and ecology.

After an ‘Introduction’ where a summary of current knowledge on benthic dinoflagellates and the terminology used along the book is provided, the ‘Material and methods’ chapter includes information about different sampling strategies, how to separate the organisms from the substrate, commonly used microscopy and culturing approaches, and an overview of studies quantifying them or applying molecular genetic methods for their characterization. Toxicity tests and toxin analyses commonly used are also presented.

The book includes a chapter on ‘Phylogeny and systema­tics’. Molecular information is missing or limited for many taxa, and phylogenetic inferences are often inconclusive, pre­ venting the establishment of their affinities. In fact, genera are organized alphabetically in the ‘Taxonomy’ chapter, and sometimes information on their taxonomy and their closest relatives is missing. This is mainly caused by the uncertainties regarding their affiliation. In this chapter, several cases are presented, relating potential evolutionary relationships estab­lished by molecular information, morphological convergent characters and affinities with planktonic relatives.

The chapter on ‘Toxins of benthic dinoflagellates and benthic harmful algal blooms’ provides a detailed overview on toxicity, diseases and effects of benthic harmful algal blooms (BHABs). Exhaustive tables including toxic compounds identi­fied, origin of species/strains and associated bibliography are provided for genera including harmful representatives, e.g. Gambierdiscus, Ostreopsis, Amphidinium, etc.

Finally, the ‘Relevance for science and society’ chapter explores the repercussions of benthic dinoflagellates on society, mostly related to their impact on human health or marine biota. Important areas for basic research directly related to benthic dinoflagellates are also discussed, e.g. dinoflagellate evolutionary studies, genetics of dinoflagellate toxicity or pro­duction of natural products and nutritional supplements.

Overall, the second edition of this book not only represents an update of new taxa discovered since the first edition was pub­lished in 2014, but many additional aspects and sections have been included and expanded. The completeness and high quality of material presented result in a book of interest not only for benthic dinoflagellate specialists, but for a wider audience, including protistologists and ecologists interested in phytoplank­ ton taxonomy, benthic microorganisms or harmful algal blooms.

Nur ein knappes Jahrzehnt nach der erfolgreichen ersten Auflage hat das internationale Team von Autorinnen und Autoren um die Meeresbiologin Mona Hoppenrath die zweite, überarbeitete und deutlich erweiterte Auflage ihres Fachbuchs über bodenlebende marine Dinoflagellaten veröffentlicht.

All diese neuen Taxa und Daten machten eine Neuauflage schlichtweg notwendig. Und die kann sich sehen lassen: 242 Arten in 63 Gattungen werden detailliert vorgestellt mit informativen Beschreibungen, mehr als 240 farbigen Mikroskop-Fotos und etwa 250 gestochenscharfen elektronenmikroskopischen Aufnahmen. Mehr als 330 hochwertige wissenschaftliche Zeichnungen runden die reichen Illustrationen der dargestellten Taxa ab. All dies ermöglicht eine zuverlässige Bestimmung der Arten dieser nicht nur biologisch, sondern auch ästhetisch sehr interessanten und ökologisch hochrelevanten Protisten-Gruppe.

Beim ersten Durchblättern des Buches mag das scheinbare Fehlen von Bestimmungsschlüsseln für die Gattungen und Arten zunächst erstaunen. Beim Lesen wird man allerdings schnell aufgeklärt: Ein Link führt zu Online-Matrixschlüsseln, die einige entscheidende Vorteile zu den sonst üblichen dichotomen Bestimmungsschlüsseln haben. Eine wirklich sehr nützliche Innovation und zugleich die Chance, die Aktualität im Gegensatz zu einem gedruckten Schlüssel wesentlich besser aufrecht zu halten, indem unter anderem zukünftige neu beschriebene, oder revidierte Taxa flexibel integriert oder umgruppiert werden können.

Da allerdings bei Dinoflagellaten, wie auch bei anderen Protisten-Taxa und sogar bei zahlreichen mikroskopischen Metazoen in den vergangenen Jahren zunehmend kryptische Arten entdeckt wurden und weiterhin werden, ist heute eine wirklich zuverlässige Bestimmung in vielen Fällen nur noch mittels zusätzlicher Analyse von DNA-Sequenz-daten möglich. Auch hier wartet die Neuauflage mit einer wirklich hilfreichen Innovation auf: Zu jeder Art sind die Zugangsnummern, wenn verfügbar, zu den relevanten Sequenzdaten („DNA-Barcodes") in den öffentlichen Repositorien angegeben.

Die Beschreibungen der Arten sind ganz klar das Kernstück, jedoch runden ein Methoden-Kapitel, eine Zusammenstellung der bisherigen Kennt nisse zu den von verschiedenen Arten produzierten Toxinen und ein taxonomischer Index dieses Buch erst ab. Für mich hätte nur das Methoden-Kapitel gerne etwas ausführlicher ausfallen können, etwa in der Art einer Methoden-Sammlung. Bisher wird nach einer knappen Beschreibung einer Methode hauptsächlich auf die jeweilige Originalliteratur verwiesen. Möglicherweise darf ich mich in dieser Hinsicht auf die dritte Auflage freuen -vielleicht wieder in knapp 10 Jahren...

Völlig neu ist das Kapitel über die Relevanz der benthischen marinen Dinoflagellaten für die Wissenschaft und Gesellschaft. Während für die gesellschaftliche Bedeutung natürlich die bereits erwähnte Toxizität vieler Arten sicherlich an erster Stelle steht, so zeigen die Autorinnen und Autoren, wie relevant die „Panzergeißler" auch für die Wissenschaft waren und sind: Viele fundamentale Erkenntnisse über die Evolution von Stoffwechselprozessen der Zelle und ihrer Organellen wurden an und mit Dinoflagellaten gewonnen. Zusammenfassend lässt sich sagen, dass „Marine Benthic Dinoflagellates - Their Relevance for Science and Society" ein fundierter Begleiter in der Praxis der Forschung sein wird und in keinem Bücherregal von Meeresbiologinnen und -biologen, sowie meeresbiologischen Laboren und Forschungsstellen fehlen darf. Der vergleichsweise günstige Preis sollte dieser Prognose keinesfalls im Wege stehen.

Das wunderbare Fachbuch ermöglicht sowohl Einsteigerinnen und Einsteigern in die Artenkenntnis - Studierende mit einem Biodiversitäts- oder Ökologieschwerpunkt als auch interessierte Amateur-Mikroskopikerinnen und Mikroskopiker - einen guten Start, wird aber gleichfalls etablierten Forscherinnen und Forschern stets ein kompetentes Nachschlagewerk sein. Einzig die bereits erwähnten Online-Matrixschlüssel für eine merkmalsbasierte Artbestimmung sind bisher noch nicht für alle Gattungen verfügbar, was den Wert des Buches an sich aber keinesfalls schmälert. Dennoch wäre es toll, wenn das Team der Autorinnen und Autoren mit der gleichen gewohnten Begeisterung und Produktivität an der Fertigstellung der Schlüssel arbeiten würde.

Kurz und gut: Die Relevanz der marinen benthischen Dinoflagellaten für die Wissenschaft und Gesellschaft ist groß - und das sie thematisierende Fachbuch absolut empfehlenswert!