How many species of seaweed do we have in Canada and are any endemic?

I often get asked questions along these lines. Typically I throw out a number of 1000 species, and try to avoid discussions regarding endemics. However, my former student Amanda Savoie, now at the Canadian Museum of Nature, sent a note last evening asking for some thoughts on such issues as she too is now receiving these questions. So I decided to put a little energy into the queries for a change.

To get an idea of the number of species, I went through our database at UNB to count the number of ‘species’ for our ~24800 Canadian specimens (not all have been genetically studied). The results were actually close to my typical response of 1000 coming in at ~900 species (all values are quick tallies).

This is of course an underestimate as there are many microscopic epi and endophytic species for which representation in our database will be moderate (low?). We also have a sweet spot in the lab for red algae, which are by far our best studied group. However, I would contend that these values are reasonable estimates in that reds are by far the most diverse group in the Canadian, and indeed many floras.

To the question, are there endemics? Absolutely! We have endemics in all three of our oceans. As an example from each, we have Waernia sp. 2GH in Haida Gwaii (northern British Columbia), Torngatum varicrassum G.W.Saunders in the Arctic, and Porphyra corallicola H.Kucera & G.W.Saunders in the Bay of Fundy, New Brunswick. But are any of these truly endemic?

Waernia sp. 2GH; a cryptic red crust growing on the holdfast of Laminaria yezoensis Miyabe in the subtidal (4 m) at SGang Gwaay (rocks to NW), Gwaii Haanas, BC.

Firstly, the previous examples are all easily overlooked – only an expert specifically trying to collect them would even have a shot at finding each. Secondly, there are no barriers to dispersal – our three ocean floras are essentially continuous with adjacent waters of the United States and nearby Greenland (I’m intentionally ignoring the islands of St. Pierre and Miquelon off the coast of Newfoundland, which are literally part of France). Consequently, sampling artifact likely contributes more to Canadian seaweed ‘endemism’ than actual endemism.

Consider for example that we have ~7700 collections from Haida Gwaii (Waernia sp. 2GH only one collection), ~1600 from the Canadian Arctic of which ~450 are from Labrador (Torngatum varicrassum G.W.Saunders type and only collection) and ~4500 collections from the Bay of Fundy (Porphyra corallicola H.Kucera & G.W.Saunders type and only collection). I think we can be confident that the respective adjacent waters of southern Alaska, western Greenland and northern Maine are not so intensely sampled with genetic tools. With time, I expect that our Canadian endemic species will be found in these adjacent waters. As a case in point; when we first described Saccharina druehlii G.W.Saunders & McDevit (currently Hedophyllum druehlii (G.W.Saunders & McDevit) Starko, S.C.Lindstrom & Martone) it was only known in Gwaii Haanas and thus a Canadian endemic. However, continued surveys by other researchers not surprisingly extended this range to Alaska (Starko et al. 2018). If we are still making discoveries for things like kelp, then it is highly likely that the less charismatic species are far more widely distributed than currently recorded.

I would speculate that there are two regions in Canada that could harbour endemic species as they both differ in abiotic factors from adjacent waters. These are the Gulf of Saint Lawrence (if we again ignore the French Islands of St. Pierre and Miquelon, which border this region) and Hudson Bay. For the latter we have indeed found uncharacterized endemic species. However, we have collected ~860 specimens there, considerably more than adjacent Arctic waters. So all bets are off, there is plenty of coastline out there. For example, we had only rare collections of Phycodrys sp. 1NB largely from the Bay of Fundy until we went to Norway where this species was common (Bringloe et al. 2019). Similarly, Platysiphon glacialis (Rosenvinge) K.Kawai & T.Hanyuda was only known from the Eastern Canadian High Arctic and nearby Greenland, but then we collected in Nome, Alaska, where this species dominated some habitats (Bringloe & Saunders 2019). Consequently the notion of endemism has to be placed in the context of sampling effort, and not only for the Canadian flora, but also sampling effort of adjacent waters and beyond.

Phycodrys sp. 1NB from the subtidal (2 m) on rock at Duck Pond Beach (rocks west), NB.

NW Atlantic Callithamniaceae and Wrangeliaceae updates

While updating the NEAS key I naively assumed that the New England Callithamniaceae and Wrangeliaceae were taxonomically sound. I should know better by now. It will take a while to sort it out but for now there are at least two anomalies in need of immediate study Callithamnion sp. 1GWS and Lophothamnion sp. 1GWS. For the former we have collections from Maine and Tasmania (introduced?). The latter is fairly interesting as Lophothamnion is considered a poorly known monotypic genus from Australia. We currently have 5-7 genetic groups assignable to this genus: Australia (n = 3), Bermuda (n = 1(2?)), South Korea (n = 1?) and this NW Atlantic species. Taxonomic work is needed. Pages for Aglaothamnion halliae (Collins) Aponte, D.L. Ballantine & J.N. Norris, Antithamnion cruciatum (C.Agardh) Nägeli (actually in the Ceramiaceae, but completed with all of these other fuzzy reds), Callithamnion corymbosum (Smith) Lyngbye, Callithamnion tetragonum (Withering) S.F.Gray, Gaillona hookeri (Dillwyn) Athanasiadis, Seirospora interrupta (Smith) F.Schmitz and Spermothamnion repens (Dillwyn) Magnus now loaded. Regrettably they are based on a very few pressed specimens in most cases. Better than nothing and a necessary task as part of updating the NEAS key… They join the earlier pages for Plumaria plumosa (Hundson) Kuntze, Ptilota gunneri P.C.Silva, Maggs & L.M.Irvine and Ptilota serrata Kützing. What little I can upload for Antithamnion hubbsii E.Y.Dawson will follow shortly (added link May 13, 2021).


2021ii20: in editing the updated NEAS key, which starts with Phaeosaccion collinsii Farlow, I became sidelined and considered the divergent COI-5P data for our Pacific and Atlantic floras.

2020.xii.30: somehow Acrosiphonia slipped through the cracks and I became distracted by the ten species of Blidingia in our flora. These pages will appear shortly…

2020.xii.8: Emphasis into early 2021 is Ulotrichales. A temporary truce with Ulothrix and Urospora spp. until they bloom late winter. Time for Acrosiphonia spp…

As an aside the revised NEAS identification keys are now in draft form for red and green algae.

The Seaweed of Canada: guide pages to assist with species confirmation!

About Seaweed are immensely varied and beautiful. Regrettably, they can also be very difficult to identify in the field, the depth of the problem only fully appreciated in the light of contemporary DNA barcoding. The intent with these pages is not to provide a comprehensive account for each species, however, it is hoped that these pages will serve as a guide to check identifications determined through the various keys that are available; notably Gabrielson & Lindstrom (2018) for British Columbia and Sears (2002) for the northwest Atlantic and, to a lesser extent, Canadian Arctic. Additional information on the North Atlantic species can be found in the comprehensive publications of Taylor (1962; a must have work; consult AlgaeBase for name updates (Guiry & Guiry 2020)), Bird & McLachlan (1992; red algae) and Mathieson & Dawes (2017). Where the potential occurs for confusion between various genetic groups that manifest as a single morphospecies, comments will be provided. Distribution is indicated following each species’ name as BC (British Columbia), Ar (Arctic) and A (Atlantic), and while the emphasis is on the Canadian flora, information on the contiguous American waters is provided in the text.

Accessing Species Pages: Species pages can be viewed by entering a genus or species name into the search window above. Or can be browsed taxonomically by major seaweed group: Chlorophyta, Phaeophyceae, Phaeosacciophyceae or Rhodophyta.

Additional Resources: Nomenclatural and taxonomic notes, including name changes and a comprehensive listing of synonyms, can be obtained by searching a species name found here in the wonderful online resource AlgaeBase. For more images of each species, similarly search in the Taxonomy Browser at the Barcode of Life Data System, but be careful as all images may not be correctly assigned (typically those starting with ‘GWS’ are from our group and at least match the species as presented here).

Disclaimer & Limitations: This is, and will remain, a work in progress both in terms of the overall flora, and the individual species pages. I would ask for your patience as I slowly upload and update the many species pages. The intent is to provide baseline information at first for all species, and then build substance to the species pages as time permits. All users are responsible for researching and questioning everything that is provided here. This is one algal taxonomist’s opinion and interpretation of the literature and species that have been studied. Reviewing the primary literature and any other pertinent resources always remain the responsibility of the reader. Enjoy!

Acknowledgements: The various morphological, ecological and geographical comments, as well as many of the images, derive from decades of fieldwork by my Laboratory group. No person is an island and none of this would have been possible without a long and fulfilling career mentoring the next generation of phycologists. This continuous stream of young and energetic minds have empowered me to complete this work through their friendship and tireless dedication to their work. Of particular note my Laboratory Manager Tanya Moore has had a significant impact on the lab’s research output for more than a decade! This work is dedicated to all of them, in addition to my loving family who have had to endure endless absences on my part. I wonder at times if they feel that I like my work more than them – that simply isn’t the case. To Dolores, Karsten and Davin, for all that you have endured and your unwavering support, my sincerest thanks and deepest love.

Citing Seaweed of Canada: Saunders, G.W. 2021. The Seaweed of Canada: guide pages to assist with species confirmation.; searched <date searched>.

Copyright & Intellectual Property: Copyright and other intellectual property rights worldwide are attributed to Gary W. Saunders.