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Three kinds of algae? Blooming marvellous news!

Bloom: From food to fuel, the epic story of how algae can save our world by Ruth Kassinger 2019. Elliott & Thompson.

As a Botanist, especially one who has taught an undergraduate module on marine biology for over 12 years, I like to think I know a thing or two about algae. However, having just read Ruth Kassinger’s book Bloom*, I realise I knew hardly anything about these incredible plant-like organisms. Which is a roundabout way of saying that Bloom is a rather wonderful book**.

Bloom, much more than a natural history book

Categorised as a Science and Nature title by its publisher, you might assume it’s a ‘natural history book’, and not therefore an entirely academic title. But, that reaction would be wrong: Bloom is as good as any botanical textbook I’ve come across and I would have no hesitation in adding it to the reading list of a module on marine biology (or on biodiversity, or on plant biology, or any course that aims to introduce the uninitiated to organisms that are generally under-represented – overlooked, ignored … – in other biology classes…). And, because Bloom provides a narrative that mirrors the author’s own personal journey of discovery of the joy of algae, this gives the book an important dimension that is usually absent from more traditional science textbooks – the thrill of finding-out, rather than having the facts placed in front of you in a rather dry way.

Not just algae, but people too…

Ruth Kassinger’s web-site says that she writes about “the intersection of gardening, history, and science”. Substituting ‘plants’ – in the broadest sense – for ‘gardening’, these three threads are admirably woven together in Bloom which therefore has a plants-and-people perspective that this reviewer really appreciates. And it’s all done in an admirably accessible way. Yes, Bloom uses technical terms – e.g. diazotrophs, heterocysts, stromatolites, hydrothermal liquefaction (HTL), photobioreactors (PBRs), harmful algal blooms (HABs), dead zones, and algal turf scrubbers (ATS) – but they are fully explained, in context, and their relevance made clear. In that way the jargon is not a barrier to comprehension, but is actually an asset that provides the key to understanding and appreciating what marvellous organisms algae really are. And that comprehensibility is helped considerably by Kassinger’s great writing style: Reading Bloom is no chore at all (and is a relatively effortless way to acquire a lot of algal knowledge).

A brief guide to its contents

Bloom is 380 pages of text, comprising c. 30 pages of selected – and somewhat annotated – Bibliography (which includes several scientific articles and popular science book titles), and 10 pages of 2-columned Index. Its 322 pages of main content don’t include in-text citations, which helps to maintain uninterrupted narrative flow, but do feature footnotes where appropriate. The main content is divided into four sections: I reviews the roles of algae in the conquest of planet Earth (both in the sea and on the land…); II explores a number of nutritional dimensions of algae; III considers the many and varied uses of algae and their products, from 17th Century glass-making to modern-day plastics and fuels; and IV is quite an optimistic section that investigates the potential of algae to help us cope with issues of global warming, and pollution of water bodies. It should be clear from those section summaries that Bloom packs in a lot of algal information – much of which was new to me. Although one might like more illustrations throughout the book – and with the addition of scale bars to impress upon the readership the actual sizes of the algae featured, those that are there are rather exquisite and one applauds illustrator Shanthi Chandrasekar’s artistic endeavours.

What are Bloom’s ‘algae’?

Kassinger reminds us that there is no exact definition of algae, and Bloom considers cyanobacteria, and eukaryotic microalgae and macroalgae (seaweeds) to be legitimate algae. Purists may disapprove of the inclusion of cyanobacteria (which, as all phycologists must acknowledge, are prokaryotic bacteria), but, since they’ve been studied by algologists for hundreds of years – under their alternative name of blue-green algae – this Botanist is more than happy with their being covered in this book. Especially since that broader definition therefore enables Kassinger to give a very impressive account of the debt owed by all life on Earth to cyanobacteria. After all, it was cyanobacteria that, billions of years ago, began to oxygenate the planet via their photosynthesis, and helped to provide a useful source of usable nutrient nitrogen for other life-forms from the ability of some species to fix atmospheric nitrogen. Kassinger develops that further to provide a great account of the development of eukaryotic algae, and the evolution of land plants (which were ultimately derived from algal ancestors). This is a great story that’s very well told, and in a way that should be accessible to a very wide audience.

Algae, food for thought – literally!

And the transformative power of algae is brought even closer to home as Kassinger considers the relevance of algae as ‘brain food’. In particular she highlights the roles played by iodine and the omega-3-oil, docosahexaenoic acid (DHA) in brain development in modern-day humans. Although nowadays we may get these from iodised table salt or eating oily fish, DHA is ultimately derived from the algae consumed by those marine fish, and there is a lot of iodine in seaweeds. A compelling argument can therefore be made that our direct ancestors were coastal dwelling humanoids in modern-day South Africa who consumed lots of ocean-derived food such as seaweeds and fish, supplemented by carbohydrate-rich plant parts from the nearby Fynbos vegetation. From a brain-building point of view, such a diet was considered far superior to a purely land-based one. So much so that, as Kassinger puts it, “Without algae in the hominin diet, we would never have parted ways with our less brainy primate relatives.” Developing that notion further, Kassinger also puts in a good word for the ‘kelp highway’ hypothesis of relevance to the peopling of the Americas.

We are told that today seaweeds comprise 10% of Japanese and Korean diets, and given many good reasons why we should all increase our consumption of these algae. Indeed, Section II “Glorious Food” is a really refreshing part of the book with lots of ‘bigging-up’ of ‘sea vegetables’ (aka seaweeds) – which are not just confined to Japanese nori or Welsh laverbread. You don’t have to be vegetarian to appreciate the dietary/nutritional benefits of algae. And let us not forget that umami – one of the 5 basic tastes – was discovered when dried kombu (one of several kelp seaweeds of the genus Laminaria)’s contribution to miso soup was investigated in Japan in 1908. Should you be tempted to try these sea vegetables for yourself, Bloom includes a collection of seaweed recipes.

Algae, the great co-operators

Although the macroalgae can be largely considered to be stand-alone examples of their kind, many of the smaller algae often work best when in an intimate association with other organisms. Accordingly, Kassinger has a lot to say about the importance of the nitrogen-fixing symbiotic cyanobacteria inside Azolla (an aquatic fern) and its relevance to the fertility of paddy rice-growing. She also provides a wealth of information about the fungus-algal mutualism in lichens, and – especially – about the animal-algal relationship that makes coral reefs possible. This emphasis upon unlike organisms working together and an appreciation of the wider ecological contribution of algae is an important message within Bloom.

Algae, reasons to be cheerful…

Although there’s a lot of doom-and-gloom around at present, Kassinger is optimistic that harnessing the power of algae can help to alleviate some of our current environmental concerns. She therefore spends quite a lot of the book looking at global climate change and aquatic pollution issues. She documents her various discussions with those who may be destined to be the movers-and-shakers of algal-based, environmentally-sympathetic techniques and technologies to help clean up the planet. But, she doesn’t just present their manifestos, she considers their claims and how realistic they are and reaches her own conclusions on a wide range of environmentally-sensitive matters. No hype, no over-selling, just sensible, rational evaluation and well-considered views – but a good deal of optimism that algae can really make a difference to mankind’s future on this planet.

Some algal facts to share…

At this point it’s tempting to reveal too many of the book’s little gems of information, so I’ll do my best not to and provide just a few tempting morsels. Readers may have heard of red snow (the algal phenomenon, not the thermonuclear weapon of the same name), but what about ‘watermelon snow’ and its relevance to climate change, or ‘rock snot’ and its connection with the ecology of temperate rivers and streams?. Similarly, red tides may be a term familiar to the book’s intended audience, but there are also ‘golden tides’, and ‘green tides’. Kassinger covers the ‘Arctic Azolla Event’ which reduced CO2 in atmosphere by 80% 49 millions of years ago and the fact that algae are implicated in recent ice ages. The 1991 eruption of Mt Pinatuba in the Philippines provided a ‘natural’ opportunity to verify the ocean iron fertilisation hypothesis, whereby an increase in algal growth can lead to a reduction in atmospheric CO2. Addition of a seaweed – Asparagopsis taxiformis – to cows’ feed can almost eliminate their production of methane (CH4), and thereby reduce the amount of this major greenhouse gas in the atmosphere. Finally, we learn that the blue-green alga Spirulina in the human diet could help to alleviate deficiencies of Vitamin A – thereby helping to solve one of the problems of blindness in so-called developing countries***. These examples have a clear environmental bias, and are therefore in keeping with the important environmental sustainability message that permeates the book, and which is a major current and future concern for us all. So, there’s lots of topicality within Bloom, which makes it suitable for ‘quoting’ in many contemporary biology or environmental science teaching sessions.

A small note of caution

Maybe a consequence of being a more-populist science text there were a few occasions when my attention was caught by statements that needed evidence – or qualification – to support them, or perhaps just to be phrased differently; e.g.

Do growing algae require no fresh water (p. xi)?; Are the oceans really “blanketed in a dense but invisible 600-foot-thick layer of them [algae]” (p. xii)?; Are there “more algae in the oceans than there are stars in all the galaxies in the universe” (p. xii)?; Are algae “dozens of times more productive than plants” (p. xiv)?; Do eukaryotes – such as micro- and macroalgae – “construct 100,000 more proteins than prokaryotes” (p. 22)?; Do fish have cell walls (p. 117); Is Ascophyllum (aka knotted wrack or egg wrack) really also known as bladder wrack as stated in Bloom (p. 132)? That common name I thought was reserved for Fucus vesiculosus, at least in the UK and Europe.

Kassinger tells us that maths and science-checking for the book was undertaken by several people (who are named on p. 323). It may therefore be the case that these ‘facts’ are correct, and all’s actually well, and it’s just the plant biology educator in me being overly-cautious. One could probably check these things on the interweb (and that exercise in itself would be a good aid to learning/reinforcing knowledge about these amazing organisms), so this may be a minor quibble. Nevertheless, just saying something is so – especially considering that these concern life-forms the intended readership probably doesn’t know that much about – isn’t the same as providing the evidence for a statement.


Bloom is a great book on algae, particularly in considering their past and future roles in relation to humankind and our quest to survive in an uncertain future. And I’m sufficiently taken by the author’s style to have ordered a copy of her previous botanical book A Garden of Marvels: How We Discovered that Flowers Have Sex, Leaves Eat Air, and Other Secrets of Plants. What better praise for Bloom can there be than that? But, if you do need a better reason to read the book, I leave you with the book’s final sentence: “Algae: they created us, sustain us, and, if we’re both clever and wise, they can help save us.”

* Bloom is also published by Houghton Mifflin Harcourt in the USA under the title Slime: How Algae Created Us, Plague Us, and Just Might Save Us, and reviewed by David Weinberg.

** If you’d like to ‘try before you buy’, a flavour of the issues covered in Bloom can be viewed – for free – in the author’s blog entry.

*** And maybe in a more environmentally-acceptable than use of genetically-modified ‘golden rice’..?

Nigel Chaffey

I am a Botanist and former Senior Lecturer in Botany at Bath Spa University (Bath, near Bristol, UK). As News Editor for the Annals of Botany I contributed the monthly Plant Cuttings column to that international plant science journal for almost 10 years. As a freelance plant science communicator I continue to share my Cuttingsesque items - and appraisals of books with a plant focus - with a plant-curious audience at Plant Cuttings [https://plantcuttings.uk] (and formerly at Botany One [https://botany.one/author/nigelchaffey/]). In that guise my main goal is to inform (hopefully, in an educational, and entertaining way) others about plants and plant-people interactions, and thereby improve humankind's botanical literacy. I'm happy to be contacted to discuss potential writing - or talking - projects and opportunities.
[ORCID: 0000-0002-4231-9082]

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