Seaweed names are sometimes presented in this book with single quotes (e.g., ‘R. californica’). These represent species of uncertain taxonomic status: they may be a new species or one already described—more work is needed. Until then, the former name in single quotes is used.
Biodiversity, the DNA Barcode and the Future of Taxonomy
“How many species of seaweeds are there?” is a deceptively simple question we are frequently asked. The answer: many more than we currently know! At the close of 2015 the excellent online database AlgaeBase includes roughly 15,000 seaweed species. This breaks down to roughly 2,000 browns, 6,000 greens and 7,000 reds. Compared to perhaps more familiar groups such as birds (approximately 10,000 species) and mammals (approximately 5,500 species), seaweeds are more diverse. And more mysterious. Scientists predict we will uncover relatively few more birds and only a smattering of new mammals; for seaweeds, we probably have thousands of species left to find.
Identifying seaweeds based on what they look like is difficult, even for experts. Seaweeds have relatively simple bodies—no eyes, flowers, feathers, etc.—and many species have only subtle differences in their appearance. Kelp are the exception, a group of easily identified species, but even here there can be hidden diversity (see Saccharina druehlii, p. 205). Adding to that is the ability of most seaweeds to be “phenotypically plastic”; in other words, the size, shape, number of branches, even colour of an individual
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About Seaweeds
Paul Silva
“On October 4, 1941, we took our first field trip, to Whites Point near San Pedro. I was amazed and even ecstatic at the sight of so many beautiful seaweeds growing on the rocks at low tide. I had gone to the beach innumerable times, but always on sandy shores and never at an extreme low tide. I changed academic pathways immediately, from higher plants to marine algae.”
Paul C. Silva (1922–2014) remembered so clearly when he fell in love. His subsequent illustrious career revolved around service to phycological societies, to the International Botanical Congress and to the University of California, Berkeley, Herbarium, where he was curator of algae for 50 years. He was an expert in nomenclature, the intricate lineages of names and their proper assignment, and his encyclopedic knowledge was generously shared with those who created or changed names of algae. His life’s work, the Index Nominum Algarum, is a database comprising 200,000 names of algae—fossil and extant, unicellular and multicellular, fresh and marine.
Although he specialized in the genus Codium, a globally distributed genus, Paul’s heart remained on our Pacific coast. His thousands of specimens resulting from numerous collecting trips throughout the California Channel Islands and along the “Lost Coast” of northern California represent some of the finest we have. His profound knowledge of the history and diversity of our beautiful West Coast seaweeds lives on in his brilliant publications and specimens.
Kathy Ann Miller
University Herbarium
University of California at Berkeley
Paul Silva, whose contributions to our under-standing of seaweeds are enormous. Photo by Kathy Ann Miller
Pacific Seaweeds
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as it’s growing can be heavily influenced by its environment (see Seaweed Communities, p. 247). Callophyllis edentata (p. 132), for example, might be tall with wide branches in a sheltered cove or short with fewer narrower branches on a wave-swept open coast. Finally, for many species an accurate ID requires knowing the habitat or features of a particular reproductive state. For specimens found washed ashore or those lacking reproductive structures, absolute identification is not possible.
What if you could use DNA to identify organisms and reduce or remove the challenges of morphology? That was the idea of Paul Hebert and colleagues from the University of Guelph when, in 2003, they proposed that DNA could be used to identify most species of animals, plants and fungi. Hebert called it the DNA barcode. The barcode is a short stretch of DNA from a certain gene in the mitochondria of cells (mitochondria are the energy-producing “engines” of our cells and contain their own DNA). Here, instead of the cashier scanning your groceries to find the prices, you could sequence the DNA barcode of an unknown seaweed, check that code against a reference library of all known species and voilà! Identification made. If your specimen doesn’t match a species in the library, then you may have uncovered something new. As of July 2015, this Canadian-driven initiative has generated 4,593,176 sequences for 249,479 species of life. The physical specimens are housed in museums and herbaria around the world, with the DNA barcode library online—Barcode of Life Data (BOLD) Systems—and housed at the University of Guelph.
At the University of New Brunswick, G.W. Saunders and his lab (including BEC during her PhD) have been developing and populating the DNA barcode library with seaweeds since 2004. This work complements Saunders’s career studying the diversity, relationships and evolution of seaweeds around the world. The Saunders Lab has “barcoded” more than 12,000 Canadian seaweed specimens, uncovering dozens of species previously unknown in these waters, and provided invaluable new information about where species are distributed. One such new species is Saccharina druehlii (p. 205), named in honour of LD. Other scientists contributing to this exciting and important work are Patrick Martone, Katy Hind and Sandra Lindstrom (University of British Columbia); Paul Gabrielson (University of North Carolina); Jeff Hughey (Hartnell College); and Kathy Ann Miller (University of California, Berkeley). Many of the taxonomic updates included in this revision are thanks to their efforts, but much work remains before we know the full
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About Seaweeds
richness of our marine heritage. A curious phenomenon arises from the use of DNA identifications. As you will discover in the species descriptions, often what was thought to be a single species, as defined morphologically, was discovered to be composed of many molecular species. In some instances, these molecular species have not been described morphologically and, often, when their morphologies have been compared, no distinguishing features have been noted. These are cryptic species … and very frustrating to the field biologist.
The initial and ongoing application of the DNA barcode was to describe and catalogue our biodiversity. As the library grows, new and powerful applications are emerging, such as revealing mislabelled food, herbs and other products. In one scandalous example, endangered fin, sei and minke whales were discovered being served as sashimi at several restaurants in California and Korea. Other endangered animals and plants have been tracked, including products such as “bushmeat,” meat from wild animals, especially in Africa and Asia, which can carry human diseases. Border agencies have used barcoding to document invasive species and crop pests in agricultural products. Steve Fain, who pioneered kelp DNA phylogenetics while at Simon Fraser University, now works for the US Fish and Wildlife Service. He uses forensic DNA studies to catch traffickers. For example, he has discovered