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Diving into the neglected world of seaweeds

Seaweeds of Britain and Ireland, 2nd edition by Francis StP. D. Bunker, Juliet A. Brodie, Christine A. Maggs and Anne R. Bunker, 2017. Wild Nature Press.

The second edition of Seaweeds of Britain and Ireland by Francis Bunker et al. [hereafter referred to as Seaweeds 2] is an important addition to the recorded natural history of the coast and near-shore seas of the British Isles *.

Of the 644 species at present recognised (Brodie et al., Journal of the Marine Biological Association of the United Kingdom 96: 1005–1029, 2016; doi:10.1017/S0025315415001484) in the UK and Ireland, Seaweeds 2 includes 238 of them. For those it provides photographic details, along with extremely useful and concise notes to help with their identification (ID). Such details include: Description; Texture and Colour (often diagnostic features for seaweed ID in the ‘field’ – and the book’s “exceptionally accurate colour rendering” is appreciatively commented upon by world-renowned seaweed expert Prof. Michael Guiry in the book’s Foreword); Reproduction (though oftentimes a compound microscope will be needed to see and appreciate such details…); Identity confusions (extremely useful in helping to distinguish your species from other similar ones); Habitat (frequently important ecological information such as where on the shore the alga may be encountered); and Distribution (which, as noted by the authors, may be patchy due to lack of suitable habitats or under-recording. Oftentimes the distribution of a species is more a reflection of the areas visited by suitably knowledgeable botanists than the real absence of species from certain locations… What better encouragement can there be for anybody to go out there and look for them?).

Also helpful for initial ID – and an important innovation from the book’s 1st edition – are the dichotomous keys at the beginning of each of the Red, Green, and Brown seaweed sections (assuming the seaweed’s colour is helpful in assigning it correctly to the appropriate colour category in the first place!). Although correct use of the key will not ID the seaweed of interest, it will place it within a group of ‘similar’ species. It’s then a case of looking at that images and descriptions to try to narrow it down to a single species. Unfortunately, this is not always possible – readily with limited equipment and without specialist knowledge – for all of the seaweeds that may be encountered. Where that is the case Seaweeds 2 importantly says so and indicates the more troublesome taxa. Whilst that can be a source of disappointment and frustration to a would-be initiate to the wonderful world of seaweeds, it is a sobering reminder that this group of organisms can be a little bit tricky. However, one likes to think that will act as a spur to the novice to persevere and take up the challenge of tackling – and conquering – this group and go on to have many more seaweed adventures.

Although Seaweeds 2 was produced as a guide for divers as part of the Seasearch project, you don’t have to be a diver or snorkeller to appreciate this book. In fact, it’s specifically for the landlubbers amongst us that Seaweeds 2 really comes in to its own. Seaweeds 2 is an ideal introduction to the macroalgae of the seashore – the intertidal zone, that expanse of coast between the high and low tide levels. Whilst Seaweeds 2 principally covers rocky shores (and near-shore subtidal habitats), that saltmarsh denizen Bostrychia scorpoides is also included, as is Derbesia tenuissima (“recently found to be common in salt marsh creeks and estuaries in Wales”). Arguably, Seaweeds 2 is at its best when the rock pool seaweed flora is considered, as one tries to unravel all those gorgeous little red seaweeds.

Seaweeds 2 is also about as up-to-date as a seaweed guide should be, and new names are evident throughout – e.g. no longer should we refer to that obligate symbiont of egg wrack as Polysiphonia lanosa (it’s now Vertebrata lanosa), or call sugar kelp Laminaria saccharina (it’s Saccharina latissima instead; although, mercifully, the common name remains the same – one of the few instances where the vernacular has a benefit over the scientific..?). In some regards Seaweeds 2 may be considered too modern, and many, like me, will mourn the separation of some species of Porphyra as Pyropia spp. and Wildemania spp. (much as they were often hard to ID as plain old Porphyra spp.!).

Much of this nomenclatural rebadging ** has resulted from more intense scrutiny of seaweeds in recent years, particularly by Profs Juliet Brodie and Christine Maggs, which thereby underlines the impeccable credentials of Seaweeds 2’s authors. However, lest that be taken as an indication of an active seaweed scene and that all is therefore hale and hearty in that area of taxonomic and biogeographical study, that really isn’t the case at all. For, and in as much as the sad fate of the mycologist is often highlighted – and deplored!, it’s probably a fact that there are fewer algologists/phycologists/seaweed-studiers around. Given that a lot of mankind’s future is dependent upon our relationship with the oceans, encouraging people to study seaweeds – above and below the water – is a most welcome initiative. I feel sure that the authors would be pleased if Seaweeds 2 encourages more individuals to start to look at seaweeds more closely.

Seaweeds 2 includes several recently-described species – e.g. Fucus guiryi, (Gerardo Zardi et al., PLoS ONE 6(6): e19402. doi:10.1371/journal.pone.0019402) and Cladophora rhodolithicola (Frederik Leliaert et al., European Journal of Phycology 44: 155-169, 2009; doi: 10.1080/09670260802573113) – which underline the potential that exists for seaweed hunters to find new species. The changing nature of the seaweed flora of the British Isles is also recognised in terms of likely effects of climate with increasing abundance and range of species such as the kelp Laminaria ochroleuca, and the presence of relatively recent invasive aliens such as Sargassum muticum, Caulacanthus okamurae, and Undaria pinnatifida.



Whatever identification text you use the important thing is to go to the seashore, look at the macroscopic algal beauties that await and begin your own personal voyage of seaweed discovery.

And, as an entrée into the colourful and exciting world of seaweed identification, Seaweeds of Britain and Ireland, 2e is great, and highly recommended! One hopes it will encourage a new generation to study these oft-neglected seashore and subtidal plant-like organisms. I’ll certainly be amending my Marine Biology module reading list with this new addition to the seaweed ID literature.


* Interestingly, the geographic scope of Seaweeds 2 is the same as that of the Botanical Society of Britain and Ireland (BSBI – http://bsbi.org/), which should allow for joined-up terrestrial and marine ‘vegetation’ cataloguing.

**  Talking of which, readers may be surprised/pleased to note that all of the species covered in the book have common names. Whilst some of the more familiar seaweeds have had common names for many years, many of the smaller more difficult-to-identify ones only had their scientific names. Where that was the case, the authors have created ‘common’ names. How well those new names will be taken up by seaweed hunters remains to be seen. Similarly, whether having common names will encourage more people to study – or at least talk about! – seaweeds, we can only hope.

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 august international phytological organ for almost 10 years. I am now a freelance plant science communicator and Visiting Research Fellow at Bath Spa University. I also continue to share my Cuttingsesque items - and appraisals of books with a plant focus - with a plant-curious audience at Botany One. 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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