Taxon-targeted metabarcoding improves distributional knowledge for Porphyra corallicola H.Kucera & G.W.Saunders

In our recent publication (Saunders & Brooks 2023) we used taxon-targeted metabarcoding to extend knowledge of Porphyra corallicola H.Kucera & G.W.Saunders with an additional record from NB and new records for NS and the low arctic in Labrador. In addition subtidal collections and three different coralline hosts were identified. The method also shed light on the distribution and ecology of conchocelis stages for other Bangiales in our flora and revealed novel taxa that may occur in only this stage as asexual species. Cody (@C_Brooks51) and I are now preparing a similar manuscript surveying kelp gametophytes in Haida Gwaii urchin barrens testing for the possibility of ‘seed banks’.

Dive log reveals rising sea surface temperatures during the short career of a silly old fool

A recent CBC article on rising sea surface temperatures in the Gulf of St. Lawrence has prompted me to share a story. It was 1985 and I was fresh out of my undergrad en route to an MSc at the National Research Council in Halifax with Jack McLachlan (father of the very talented musician Sarah McLachlan, but that’s another story). As luck would have it there was a major project surveying seaweed around Prince Edward Island that summer focused on the shifting balance between the economically preferred Chondrus crispus Stackhouse and the introduced Furcellaria lumbricalis (Hudson) Lamouroux. It was a dream job for a budding scientist with a passion for scuba.

Pic of a much younger Gary coming out on the beach in 1985. Taken by my dive buddy that day (apologies, but not sure which member of the team it was).

I logged ~50 dives; most were routine underwater transects between 2-10 m depth in waters approaching 20o C. However, there were a few dives that stood out and received special attention in my dive log. An aside; dive logs are records of every dive. How deep, how long, dive buddy, air used, water temperature, noteworthy observations … you get the idea. Back to those few special dives that received extra comments in my dive log.

At about 15 m depth there was a perceptible layering of the water column – my first encounter with a thermocline! While basking in the 20o C water, you could stick your hand through and feel the colder water below. You shiver as your body slips into the cooler water, but enjoy your time knowing that a few meters above warmer water awaits your return. As a marine biologist there is the added thrill of a clear shift in biodiversity. We were just kids and the best we could do when we hit the surface was ‘did you see that big red blade…?’. We didn’t know the flora well and I certainly did not aspire to be a taxonomist at that time (I did not know what taxonomy was until stumbling into the discipline as I progressed through my MSc). However, there are those charismatic species that grab your eye and you just have to know what they are because you have never seen anything like it before. For some folks those species are whales and the like, but for me that species was Odonthalia dentata (Linnaeus) Lyngbye. You could not miss it nor mistake it for anything else and so it, like the thermocline, received mention in my dive log on these few occasions.

Odonthalia dentata (Linnaeus) Lyngbye. What a beauty!

Fast forward three decades and I had a better grasp on taxonomy, as well as the NW Atlantic and Arctic floras. I developed a strong interest in postglacial recolonization of these regions and attracted a very talented (although lacking the vocal range of Sarah) PhD student, Trevor Bringloe, to work on this project. We collected at numerous sites from Bergen, Norway to Nome, Alaska, and from Birchy Head, Nova Scotia to Qikiqtarjuaq, Nunavut. We were targeting (sub)arctic seaweed species, which it turns out includes Odonthalia dentata. In our quest for southerly populations, I recalled my adventures in Prince Edward Island and dusted off my dive log from 1985. And so off we went in 2016 on another grand adventure – some 30 years after my summer there – to dive below the thermocline and collect these charismatic species.

Our first dive was at one of the locations carefully recorded in my dive log from 1985, which indicated the presence of a thermocline below which our treasures awaited. We did two dives, to 14.2 m and nearby to 14.4 m, but there was neither thermocline nor treasure in sight. The next day we tried another site and went to 15.9 m only to match the disappointment of the previous day. After repeated attempts, and in some desperation, we descended to 22.4 m on the final dive of the trip. Even at that depth the water was remarkably a balmy 19o C, but there, about as low as seaweed will grow in these waters, we found remnants of the once luxuriant subarctic flora of Prince Edward Island. Clearly the water was still cold enough for at least part of the year at that depth for these species to persist.

Trevor as we hit the bottom on our last dive and realized our success. Not much older than I was in 1985…

The 2016 trip had a profound impact on me. Had the water temperatures really warmed that much during the three decades between 1985 and 2016? The data in my dive log are clear, the answer is yes and the CBC story mentioned above came as no surprise.

We should have realized early in the trip that we had embarked on a difficult task. After that first unsuccessful dive I asked our young boat attendant, a local diver himself, where we could dive to find the thermocline. He responded that ‘there is no thermocline on Prince Edward Island’ and looked at me like I was some silly old fool. Although the information on which he based his opinion of me was inconsistent with the data in my dive log, it was nonetheless a sound assessment. I would encourage my cherished colleagues, other silly old fools, to explore their dive logs as well. There are data in those sheets!

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. 2019b). 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 2019a). 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. 2023. 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.