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The Potential Use of Seaweeds and Marine Plants by Native Peoples of Alta and Baja California: Implications for “Marginal” Island EcosystemsImplications for “Marginal” Island Ecosystems


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Archaeologically, the use of marine kelps and seaweeds is poorly understood, yet California's islands are surrounded by extensive and highly productive kelp forests with nearshore habitats containing more than 100 edible species. Historical accounts from around the Pacific Rim demonstrate considerable use of seaweeds and seagrasses by native people, but there has been little discussion of seaweeds as a potential food source on California's islands. This chapter summarizes the biology, diversity, ecology, and productivity of marine macroalgae and marine angiosperms in the California Bight, supporting the likely consumption of seaweeds in the past. The potential use of plentiful and nutritious seaweeds by California Island peoples has major implications for the perceived marginality of the islands.
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e Potential Use of Seaweeds and Marine Plants
by Native Peoples of Alta and Baja California
Implications for “Marginal” Island Ecosystems
 . ,  . ,  . ,
 . ,   . 
Around the world, humans cultivate and use seaweeds (Mouritsen )
for a variety of purposes, fostering a vast aquaculture industry that harvests
around  million tons annually (Bostock et al. ). Seaweeds are widely
used as food, fertilizer, and animal feed and as sources of potash, agar,
alginic acid, cellulose, iodine, and other food additives and compounds
(Chapman ; Evans ; Mouritsen ; Wang and Chiang ). e
earliest known written record of seaweed use appears to be a Chinese herbal
guide dated to  BC (Bell , ), and archaeological evidence dem-
onstrates that Native Americans have harvested seaweeds for at least ,
years (Dillehay et al. ). Edible seaweeds provide a variety of nutrients
essential to human health, including high levels of proteins, amino acids,
vitamins, minerals, and essential fatty acids and many medicinal benets
(Dawczynski et al. ; Gupta and Abu-Ghannam ; Pereira ; Silva
et al. ). e modern cultivation and consumption of seaweeds has
prompted the use of the term sea vegetables (Tseng a). Seaweeds were
also a major potential food source for ancient island and coastal peoples
globally, including many islands o the Pacic coast of North America.
More than  species of seaweed (including kelps) are consumed
worldwide (Evans ; Kumar et al. ; Mouritsen ). e highest
numbers of commonly consumed seaweed varieties grow in China, Ha-
waii, and Taiwan (– species) (Wang and Chiang ; Xia and Abbott
); many varieties also grow in the Philippines (n = ) and Japan (n =
) (McManus ; Trono ). Importantly, except for seaweeds that
 · A. F. Ainis, J. M. Erlandson, K. M. Gill, M. H. Graham, and R. L. Vellanoweth
are impregnated with calcium carbonate or possess high concentrations
of acid, all seaweeds are inherently edible. Around the world, indigenous
peoples recognized seaweeds as important sources of food, medicine, and
other materials (Chapman , –; Mouritsen , –). e
high salt content of seaweeds in the form of alginate makes them excellent
preservatives (Smith a, ; Tseng b); this salt is commonly used to
give meat products a longer shelf life (Hoppe and Schmid , ). Wrap-
ping meats or other perishable food items in moist and salty seaweed might
have been an eective means for coastal peoples to temporarily preserve
shellsh, sh, and marine mammal meat, especially if they could keep such
bundles cool.
Despite their importance in many coastal societies today and the exten-
sive historical and ethnographic evidence for their past use (see below),
archaeologists rarely discuss the potential use of seaweeds among more
ancient societies. is is due, in large part, to the fact that seaweeds rarely
preserve in archaeological or paleontological contexts (Bell ; Dimbleby
, ; Parker and Dawson ). A lack of abundant archaeological evi-
dence for seaweed use, however, does not mean that coastal people did not
use them to a signicant degree in the past. Given their importance histori-
cally and today, seaweeds should be included in our discussions of ancient
subsistence in coastal environments. Biagi and Nisbet () highlighted
the potential importance of seaweeds in ancient coastal economies, for in-
stance, and Erlandson et al. () discussed their potential importance
in sustaining maritime peoples following a Pacic Rim route from north-
east Asia into the Americas. A few archaeologists have proposed methods
for indirectly identifying seaweed use in the past (Bell ; Colonese and
Wilkens ; Rowland ), including Ainis et al. () who showed
that seaweed use could be identied in California shell middens by identi-
fying mollusks closely associated with marine algae and plants.
In this chapter, we summarize the biology, ecology, and productivity of
marine seaweeds and plants of Alta and Baja California. We show that these
marine algal and plant resources were highly diverse, abundant, nutritious,
and potentially important to the native peoples of California’s islands. We
review historic accounts from the Pacic Rim and Pacic Basin to show
that indigenous peoples used seaweeds and marine plants extensively for
centuries or millennia. We then summarize a growing body of data for
ancient human use of seaweeds and explore methods for identifying the re-
mains of these highly perishable resources. As evidence mounts for inten-
sive use of endemic terrestrial plants on the California islands (see chapter
Use of Seaweeds and Marine Plants by Native Peoples of Alta and Baja California · 
, this volume), we suggest that native inhabitants also harvested and con-
sumed sea vegetables, which raises further questions about the supposed
marginality of island resources.
B B
Marine vegetation consists of algae and angiosperms. Marine algae have
benthic (attached to the sea oor) and planktonic forms (free oating and
mostly unicellular) (Levring a). Dierences in their organization and
construction separate marine algae (seaweeds and kelps) from the marine
angiosperms (seagrasses), which are true owering plants. Seaweed is the
common term for marine macroalgae, which include a variety of forms
that lack root systems, buds, owers, or seeds (Chapman ; omas
). ey are photosynthetic protists that are distinguishable by various
structural and chemical attributes and are dened by their larger size, mul-
ticellular construction, and attachment to substrata (Dawes ; Little et
al. ; Lobban and Wynne ).
Seaweeds are partitioned into three main divisions with a high degree
of variation: Chlorophyta (green algae), Phaeophyceae (brown algae), and
Rhodophyta (red algae) (Chapman ; Dawes ; J. Graham et al. ;
Lobban and Wynne ). Fossil evidence suggests that seaweed evolved
roughly . billion years ago, while seagrasses evolved about  million
years ago (Dawes ; J. Graham et al. ). Although the physiology of
seaweeds is primitive, they have continued as the dominant form of ma-
rine vegetation despite the subsequent evolution of more complex marine
plants (i.e., vascular seagrasses).
e broad characteristics of seaweeds include holdfasts for attaching to
the substratum, fronds or blades for photosynthesis, and a stemlike stipe
that allows the blade to rise to the water surface instead of resting on the
ocean oor, although some species consist simply of a at sheet of tissue (e.g.
Ulva) (Chapman ; Little et al. , ; omas ). Seaweeds do not
need a root system for nutrient absorption, as they absorb nitrogen, phos-
phorus, carbon dioxide (bicarbonate), and trace elements directly from sea
water (J. Graham et al. ; omas ). Photosynthetic chloroplasts
are present in the surface tissues of most seaweeds, and larger species have
gas-lled bladders to keep their blades oating closer to the surface for
light absorption. Holdfasts mechanically anchor seaweeds to substrata and
withstand the eects of turbulent waters (Denny ; omas ). Sea-
weeds are constructed of branched threads, or laments, that are composed
 · A. F. Ainis, J. M. Erlandson, K. M. Gill, M. H. Graham, and R. L. Vellanoweth
of mucilaginous and gelifying substances, an architecture that gives the
plant exibility, elasticity, and tensile strength (Delf , ; Denny ).
For the most part, carbohydrates (alginate, carrageenan, and agar) provide
structural support for stipes and blades (Mouritsen , ). Although
specic molecular structures vary by seaweed species, in general, these car-
bohydrates bind with water to create the gel-like substances that are widely
used in the modern production of various food items, medications, and
other products.
Growth rate varies dramatically among seaweeds, which include an-
nual and perennial taxa. Some annuals are short lived, including the com-
monly eaten sheetlike red/purple lavers (Porphyra spp.) and sea lettuce
(Ulva spp.), which live for only a few weeks. e larger annuals tend to
have very high growth rates; giant kelp (Macrocystis spp.) can grow up to
 centimeters per day (Chapman , ) and bull kelp (Nereocystis spp.)
may grow to lengths that exceed the height of mature trees within a sea-
son (omas , ). Many seaweeds are perennial and live for several
decades, although for some species the fronds are produced annually and
only the basal structure is perennial (omas , ). Seaweed life cycles
are complicated and varied, but most have both asexual and sexual repro-
ductive phases (J. Graham et al. ; omas ). Further details can
be found in Dawes (), Lobban and Wynne (), Dixon (), and
other sources. rough a combination of rapid growth and the production
of billions of spores annually, seaweeds are a signicant source of organic
matter in coastal ecosystems.
Green algae (Chlorophyta) are found primarily in freshwater environ-
ments; only around  percent occupy marine ecosystems. Most of the ma-
rine taxa are macroalgae, many of which are edible and widely used as food.
e green algae are most similar to vascular plants; they have identical pig-
ments and produce starch as the nal product of photosynthesis (Levring
b). Molecular data indicate that the higher plants evolved from the
chlorophytes (Lewis and McCourt ). Currently, nine classes of green
algae are recognized. e widely eaten sea lettuces belong to the Ulvophy-
ceae, which contains most of the green seaweeds.
Brown algae (Phaeophyceae, in the phylum Ochrophyta) are multicel-
lular algae found exclusively in marine ecosystems. More than  gen-
era and more than , species have been identied, including the large
brown algae commonly referred to as kelps (order Laminariales; Dawes
Use of Seaweeds and Marine Plants by Native Peoples of Alta and Baja California · 
; Wynne ). At least  brown algae are commonly consumed today
(Evans , ). Most of the larger brown algae require hard substrate for
attachment, although many of the smaller lamentous species oat freely or
are epiphytes attached to animals or other seaweeds (J. Graham et al. ).
e widely used kelps (Macrocystis spp., Nereocystis spp., and Saccharina
spp.) and rockweeds (Ascophyllum spp. and Fucus spp.) are members of this
class. eir morphologies range from simple branched lamentous forms
to the highly complex organization of the kelps. Brown algae range in color
from dark brown to yellow and olive green (Levring b; Mautner ).
Most brown algae inhabit the intertidal and upper sublittoral zones and
achieve optimal growth and development in colder waters (Denny ; J.
Graham et al. ; M. Graham et al. ).
Red algae (Rhodophyta) are the oldest and most morphologically com-
plex of the three seaweed clades. Over , species inhabit marine envi-
ronments worldwide (J. Graham et al. ; Mouritsen , ; omas
, ). More than  of these species are commercially important, and
at least  have been documented as being used by humans for food in
modern times (Evans , ). Red algae can occupy greater depths; they
grow predominantly on rocks or as epiphytes on seagrasses and marine
algae and extend to the lower limits of sea vegetation at a depth of –
meters, or  meters in extremely clear waters (Levring b).
Seagrasses are marine owering plants rather than true grasses (Poaceae).
Less than . percent, or roughly  species, of owering plants inhabit
submerged marine habitats worldwide (Dawes ). Seagrasses primar-
ily inhabit sheltered bays and estuaries with sandy substrate (e.g., eelgrass,
Zostera marina), although several species of surfgrass (Phyllospadix spp.)
form extensive meadows in rocky nearshore environments (Little et al.
, ), a primary intertidal habitat of the Channel Islands. Similar to
kelp forests, seagrass meadows are highly productive marine ecosystems
and primary producers in coastal environments (M. Graham et al. ).
ey are oen linked with productive sheries because they form critical
nursery habitats for many sh taxa (Jackson et al. ).
Seagrasses have evolved a variety of physiological adaptations that al-
low them to ourish in submerged aquatic environments (Dawes ,
–; Little et al. , ). For instance, CO is absorbed across the
entire leaf surface and they are anchored to the rocks with stolons and roots
that absorb nutrients from the surrounding water. Seagrasses also have air
 · A. F. Ainis, J. M. Erlandson, K. M. Gill, M. H. Graham, and R. L. Vellanoweth
chambers (lacunae) that extend through the roots, rhizomes, blades, and
shoots, allowing gas exchange throughout the plant (Dawes , –).
Seagrasses typically reproduce sexually, but vegetative growth can replace
sexual reproduction (via rhizomes) when necessary (Dawes , ).
Seaweeds and Seagrasses in the Southern California Bight
Early accounts describe a remarkable abundance of seaweed and kelp o
the coasts of Alta and Baja California (Crandall ; Frye et al. ; Smith
b) Kelp forests were so thick in San Diego Bay during the mid-s
that they were mistaken for a low island (Anderson , ). Smith (b)
suggested that the seaweed resources o the Pacic coast of North America
were on par with those of the Japanese archipelago, which Abbott and Hol-
lenberg (, ) listed as the geographic region with seaweed populations
most similar to those of California, both of which are the most diverse and
dense in the Pacic region.
Murray and Bray (, ) identied  seaweed species in the
Southern California Bight:  species of green algae,  species of brown
algae, and  species of red algae. Four types of seagrasses are also found
in the bight, including ditch-grass (Ruppia maritima), which is actually a
salt-tolerant freshwater species; eelgrass (Zostera marina); and two species
of surfgrass (P. scouleri and P. torreyi) that form extensive meadows in shal-
low subtidal and intertidal areas (Mondragon and Mondragon ; Mur-
ray and Bray ). Murray et al. () found that seaweed diversity was
highest in the Santa Barbara Channel area (–° N latitude), where 
species have been identied. Over  genera of edible seaweed, many of
which contain multiple species, inhabit California island waters and were
available to island peoples for millennia (see Abbott and Hollenberg 
for an extensive taxonomic list of southern California species).
e high biodiversity in the Southern California Bight is attributable
in part to the mixing of marine currents (M. Graham et al. ). e
warmer northbound waters of the Southern California Countercurrent col-
lide with the cooler southbound waters of the California Current, fostering
a wide array of marine organisms. Here, native peoples hunted sea mam-
mals and sea birds, shed, and collected crustaceans and shellsh from
kelp forest and intertidal habitats for more than , years (Braje et al.
; Erlandson et al. ). Island kelp forests are extensive, contributing
to high marine productivity and sheltering a wide variety of sh, shell-
sh, and other organisms (Graham ; M. Graham et al. ; McGinnis
). e seaweeds north of Point Conception have greater biomass but
Use of Seaweeds and Marine Plants by Native Peoples of Alta and Baja California · 
lower taxonomic diversity than those to the south, where sea surface tem-
peratures above °C promote increasingly more subtropical taxa along the
Pacic coast of Baja California (M. Graham et al. ; Reed et al. ).
Kelp forests are dynamic ecosystems, susceptible to climate and weather
shis such as El Niño events and severe storms that cause changes in water
temperature, nutrient levels, and canopy cover (Dayton and Tegner ;
M. Graham et al. ; Tegner and Dayton ; Wilson and North ).
As the composition and extent of kelp canopies vary through space and
time, the associated organisms shi accordingly (Graham ; Steneck
et al. ). Rising postglacial seas have dramatically changed the coastal
conguration of Alta and Baja California since humans initially colonized
the islands, altering the distribution and abundance of kelp forests, other
seaweed varieties, and seagrass meadows (M. Graham et al. ; Kinlan
et al. ; Meling-López and Ibarra-Obando ). Such changes may
help explain the near-disappearance of sea turtle remains in archaeologi-
cal sites on Isla Cedros aer approximately , years ago (Des Lauriers
, –). e dynamic nature of nearshore marine environments in
the Southern California Bight suggest that changes in currents, shoreline
conguration, sedimentation, sea surface temperatures, and other factors
have continuously reshaped kelp forest, estuarine, and other coastal ecosys-
tems for millennia.
e pace of such changes has probably increased historically, however,
as dam building, stream channelization, overgrazing, overshing, soil ero-
sion, pollution, and now accelerating sea level rise have all aected local
beach and nearshore habitats. For instance, Dawson (), who compared
survey data from the late s to herbarium records from the early twen-
tieth century, documented a – percent reduction in species richness
at sites with high sewage outfall into the ocean. Later studies conrmed
modern anthropogenic eects on seaweed communities of the Southern
California Bight (om and Widdowson ; Widdowson ), although
Harris () reported an increase in seaweed diversity aer improvements
in sewage treatment. Studies elsewhere along North America’s west coast
have also documented a decline in species richness and density due to eu-
trophication caused by a variety of human-driven impacts of commercial
sheries since European colonization (Lotze and Milewski ). e ef-
fects of exponentially increasing anthropogenic activities have certainly al-
tered the nature of seaweed communities, which were likely more extensive
at various times in the past.
 · A. F. Ainis, J. M. Erlandson, K. M. Gill, M. H. Graham, and R. L. Vellanoweth
Kelp Forest Ecosystems
California kelp forests are among the most productive ecosystems on earth,
providing habitat, nutrients, and shelter for numerous organisms (Dayton
; Foster and Schiel ; M. Graham et al. ; North ). Dense kelp
forests are benecial to coastal inhabitants as they reduce turbulent wave
action with their bulk, subsidize terrestrial productivity with a wide range
of marine organisms, and provide benecial holdfasts that boats could be
anchored to, a feature that enabled people to more easily sh and hunt in
these oshore forests (Erlandson et al. , ; Figure .). Giant kelp
(M. pyrifera), bull kelp (N. luetkeana), southern sea palm (Eisenia arborea),
oarweed (Laminaria farlowii), feather boa kelp (Egregia menziesii), and elk
kelp (Pelagophycus porra) form vertically structured habitats that extend
from the ocean oor to the sea surface (Chapman , –; Foster and
Schiel ; Hoppe , ). Giant kelp is by far the dominant species in
the kelp forests that surround the California islands. It is a perennial that
grows best on rocky substrates in areas with continuous swell (M. Graham
et al. ). e lengths of its stipes can exceed  feet and forests can be
up to several kilometers wide (Dayton ; North ). e kelp forests
between Isla Cedros and Point Conception are dominated by giant kelp,
whereas bull kelp and winged kelp (Alaria marginata) occur in higher den-
sities north of Point Conception (North ; Tseng ).
Kelp forests are divided into three morphological groups distinguished
by the height of their fronds and their location (Dayton ; Schiel and
Foster ). e kelp varieties that produce surface canopies include the
largest species, such as giant kelp and bull kelp, whereas kelp varieties with
shorter stipes provide understory canopies. Kelp forests are oen com-
posed of all three types of canopy, which creates a tiered eect that provides
diverse habitat niches for specialized kelp obligate fauna (see Graham ;
Schiel and Foster ) and a high degree of structural, taxonomic, and
ecological diversity.
e size and productivity of kelp forests oscillate over short and long
temporal scales due to variation in available nutrients and light, ocean
temperature, and storm events (Dayton et al. , ; M. Graham et al.
; Tegner and Dayton ) and to predator/prey interactions such as
the presence or absence of sea otters and the intensity of sea urchin grazing
(Dayton et al. ; Estes et al. ; Steneck et al. ). Although the ex-
tent of kelp canopy coverage varies, kelp cover surveys from the early s
indicate that the most extensive kelp forests along North America’s west
Use of Seaweeds and Marine Plants by Native Peoples of Alta and Baja California · 
Figure .. Kelp forests and seagrass meadows surrounding the California Channel Is-
lands: (A) giant kelp (Macrocystis pyrifera) o the California coast (photo by Eric Kilby,
CC-BY-SA-. https://www.@N/); (B) kelp o
Santa Cruz Island, from sea cli,  (photo by K. Gill); (C) surfgrass (Phyllospadix spp.)
meadow at low tide on Santa Cruz Island,  (photo by K. Gill).
coast occurred between Point Conception and Isla Cedros (Tseng ).
Surveys in the s estimated that kelp forests covered an area of approxi-
mately  square kilometers the Southern California Bight. Roughly half of
the seaweed biomass for the region is adjacent to the mainland coast; the
other half is found in waters surrounding the islands. San Nicolas Island
alone accounts for more than  percent of the total for the bight (see Mur-
ray and Bray ; Figure .).
N C  S
Virtually all seaweeds are edible, but not all are ideally suited for human
consumption. e high nutritional quality of seaweeds makes sea vege-
tables a favored food in many parts of the world. In coastal and island
environments, where sea mammals, sh, and shellsh provide ample pro-
tein, seaweeds can balance the diet by supplying carbohydrates, including
dietary bers, calories, and essential vitamins and trace minerals. Only the
 · A. F. Ainis, J. M. Erlandson, K. M. Gill, M. H. Graham, and R. L. Vellanoweth
Figure .. Some of the edible seaweed taxa noted in ethnographic accounts of Native
Californians (image composite by A. Ainis): (A) sea lettuce (Ulva spp.) on the north coast
of San Nicolas Island (photo by R. Vellanoweth); (B) rockweed (Fucus gardneri) (photo by
Steve Lonhart, NOAA); (C) oarweed (Laminaria digitata) (photo by Leslie Seaton, CC-
BY-. https://www.@N/); (D) sea palm (Postel-
sia palmaeformis) (Wikimedia Commons).
carbohydrates produced by green algae are digestible by humans, although
our discussion below contains one known exception. e nutritive quali-
ties of seaweeds are oen equal to or exceed those of many commonly
consumed terrestrial plants (Madlener ; Ryther ). For instance, the
vitamin B content of green marine algae is oen higher than in many veg-
etables. Many marine algae contain signicant amounts of B, a vitamin
lacking in most terrestrial vegetables (Nisizawa et al. ). Although nu-
tritional properties vary, by dry weight seaweeds generally contain roughly
– percent fats, – percent ber, – percent protein, and – percent
soluble carbohydrates (Chapman ).
Table . provides nutritional data for some key seaweed taxa found in
California island waters. Nutritional content varies signicantly, although
there are some commonalities among general types (Chapman ; Mou-
ritsen ). For instance, hollow green weed (Ulva intestinalis) is lower in
sodium and higher in calcium and iron than both sea lettuce (U. lactuca)
Use of Seaweeds and Marine Plants by Native Peoples of Alta and Baja California · 
Table 5.1. Proximate composition (percent dry weight) of select seaweeds
Taxon Protein Fat
(undi.) Fiber Nonber Kcal
Enteromorpha spp. 19.5 0.3 6.8 46.1 265
Gelidium sp. 11.8 0.9 43.1 228
Ulva spp. 24.4–26.1 0.7–1.8 61.8 46.1 5.1 131
Monostroma spp. 20.0 1.2 57.2 6.7 111
Laminaria spp. 4–7.5 0.7–2.4 36.5–57.7 4.6–10.2 31.9–47.5 196
Sargassum sp. 13.6 0.5 61.6 305
Alaria spp. 17.1 3.6 39.8 260
Gracilaria sp. 19.7 0.4 63.1 335
Palmaria sp. 13.9 ± 0.3 1.8 ± 0.1
Porphyra spp. 33–47 0.7–2.1 40.7–46.4 2.0 44.4 350
Sources: Data compiled from Kumar et al. 2008; Nisizawa et al. 1987; Sánchez-Machado et al. 2004;
Fleurence 1999; Smith 1905a, 1905b.
Note: Kcal estimated per 100 g portion, using values of 4 for protein and digestable carbohydrates
and 9 for fats.
and wittrock (Monostroma spp.), though all are green marine algae (Ni-
sizawa et al. , ). Red/purple lavers (Porphyra/Pyropia spp.) are rich
in vitamin A, vitamin C, and several B vitamins (Hoppe and Schmid ,
; Nisizawa et al. , ), which makes them benecial in a diet lacking
in fresh fruits and vegetables. ough ber is generally low (– percent)
in kombu (edible kelp, primarily Saccharina), nonbrous carbohydrate
content can exceed  percent (Nisizawa et al. , ). In Table ., we
summarize data on vitamin content for seaweeds endemic to the Southern
California Bight to demonstrate their potential nutritional value to native
peoples of the region.
Generally, seaweeds are also good sources of many trace elements that
are essential to human health (Rao et al. ; Rupérez ). Iodine is not
produced by the human body, but the thyroid gland needs it to produce
hormones that control metabolism and other necessary bodily functions
and prevent mental impairment (cretinism) and other serious illnesses.
Iodine is particularly essential during pregnancy and infancy, when it is
needed for bone and brain development (Zimmerman ). Many types
of seaweed absorb iodine from seawater (where it occurs in trace amounts)
Table 5.2. Vitamin content of some edible seaweed taxa
A (IU) B complex B1 B2 Niacin C B6Biotin Folic Acid Choline
Enteromorpha spp. 13,000 6.0b20.5b65b432b
Ulva spp. 590 0.014a0.8b5.7b118b120b 0.224a0.118a0.061a
Monostroma spp. 2,700 429b4.3b13.3b35b540b 0.115b0.429b0.079b
Laminaria sp. 430–440 0.031a0.08a0.32a1.8a91a11.0a
Gelidium spp. 0.041b 0.061b0.782b4.885b
Gracilaria spp. 800 0.013b 0.018b0.304b1.492b
Porphyra tenera ≤ 44,500 ≤ 0.25a≤ 1.24a≤ 10a831a20a0.294a0.088a2.92a
Porphyra spp. 16,000 12.9b38.2b110b1125b10.4b- - 2,920b
Sources: Data compiled from Kumar et al. 2008; Nisizawa et al. 1987; Xia and Abbott 1987
aValue given in mg/g
bValue given in ppm
Use of Seaweeds and Marine Plants by Native Peoples of Alta and Baja California · 
and accumulate it in high concentrations (Delf , ). Some species
of sugar kelp (Saccharina spp.), for instance, can store  times the iodine
content of surrounding ocean water (Hoppe and Schmid , –).
Table . summarizes the elemental composition of some seaweeds that
were readily available to island peoples of Baja and Alta California.
Seaweed proteins dier from terrestrial plants in that they contain all or
most of the amino acids, including the essential fatty acids we must obtain
from food (Mouritsen , ). Red/purple lavers (Porphyra/Pyropia) have
a particularly high protein content that contains all amino acids including
taurine, which contributes to the elimination of excess cholesterol, lower-
ing levels in the bloodstream and potentially accounting for low instances
of high cholesterol among Asian populations who eat copious amounts of
seaweed (Mouritsen , ).
For California islanders, foods rich in carbohydrates and ber were criti-
cal to creating nutritionally balanced meals that complemented protein-
rich shellsh, sh, marine mammals, and birds. Seaweeds contain several
forms of carbohydrates that vary by type and abundance between species,
including a variety of sugars, soluble dietary ber, and insoluble dietary
ber (Mouritsen , ). ough the human gastrointestinal tract cannot
digest carbohydrates in the form of ber, they are an essential component
of the human diet. e algal bers that compose signicant percentages of
carbohydrates in many seaweeds promote the proliferation of benecial in-
testinal ora and acts as a hypoglycemic, among other healthful functions
(Dawczynski et al. , ). Various brown and red seaweeds are espe-
cially rich in dietary ber and contain higher quantities than most fruits
and vegetables (~/ grams by dry weight; Dawczynski et al. ),
yet do not produce starch or the alpha-linked glucans that most human
populations are able to digest (Hehemann et al. ). Hehemann et al.
() found that Japanese populations, who are known for their long his-
tory of extensive seaweed consumption (estimated at ~ g/day; Fukuda
et al. ), contained the enzymes that are necessary for digesting car-
bohydrates from red laver (Porphyra/Pyropia). It is believed to have been
transferred from microbes on marine red algae over the course of consum-
ing copious amounts of seaweeds for hundreds, and likely thousands, of
years. e porphyran-digesting enzyme was found to be common among
Japanese individuals but absent in metagenomic data from modern North
American populations. It is unknown whether Natives Americans pos-
sessed gut microbiota similar to modern-day Japanese populations. Fur-
ther genetic studies have the potential to reveal whether native populations
Table 5.3. Elemental composition of some edible seaweed taxa
Taxon Na KCa Mg Fe Zn Mn Cu P I Se
Entermorpha spp. 0.57a3.5a0.91a 350a 0.80a
Ulva spp. 1,100 700 730 2,800 100 1–35 20
Ulva spp. 3.183a0.731a1.12a 62a 0.094a
Monostroma spp. 1.8a0.81a0.69a 25a 0.2a
Alaria sp. 4,200 7,500 1,000 900 18 3.4 1.0 0.17 500 17
Eisenia sp. 4,000 1,200 12 0.3 50–500
Fucus sp. 5469 ± 60 4,323 ± 46 938 ± 7 994 ± 13 4.2 ± 0.17 3.71 ± 0.37 5.5 ± 0.11 < 0.5
Laminaria sp. 3818 ± 43 11,579 ± 128 1,005 ± 5 659 ± 6 3.29 ± 0.54 1.77 ± 0.44 < 0.5 < 0.5
Laminaria sp. 31,110b67,780b7,890b7,570b 4b4b2b2,220b2,500b4b
Sargassum sp. 15,000 1,400 30 60 40–60
Chondrus sp. 4,270 ± 62 3,184 ± 0 420 ± 22 732 ± 6 3.97 ± 0.11 7.14 ± 0.13 1.32 ± 0 < 0.5
Palmaria sp. 1,700 8,000 200 300 33 2.9 1.1 0.38 400 5
Porphyra spp. 3,627 ± 115 3,500 ± 71 390 ± 17 565 ± 11 10.3 ± 0.41 2.21 ± 0.17 2.72 ± 0 < 0.5 500 0.5–1.5
Porphyra spp. 5,700b24,000b4,400b 130b100b20b14.7b6,500b 0.8b
Sources: data compiled from Mouritsen 2013; Nisizawa et al. 1987; Rupérez 2002.
Note: Amounts quantied as mg/100 g dry weight unless otherwise noted.
a Quantied as percent (%) dry weight .
b Quantied as ppm (parts per mil).
Use of Seaweeds and Marine Plants by Native Peoples of Alta and Baja California · 
living in island and coastal environments acquired this or similar adapta-
tions to seaweed consumption. Recent research has shown that California
islanders relied more heavily on the corms of blue dicks and other terres-
trial plant foods than was previously realized; this provided a signicant
terrestrial source of carbohydrates and calories (Gill ; Gill and Hoppa
; Reddy and Erlandson ). e abundant seaweed species in island
waters were another major carbohydrate and dietary ber source that was
readily available year-round.
Humans cannot synthesize monosaturated and polyunsaturated fatty
acids on their own; this essential dietary component must be acquired from
foods. Marine resources generally are good sources of these fats, leading
some scholars to connect aquatic adaptations to encephalization and brain
development in human evolution (Cunnane and Stewart ; Will et al.
). Seaweeds contain signicant quantities of essential fatty acids that
have a good balance of the omega- and omega- fatty acids required for
human health (Mouritsen , –). Percentages vary by species and
season, but approximately – percent of their fat content is composed
of polyunsaturated fats, including essential nutrients such as arachidonic
acid (Mouritsen ), which is not found in terrestrial plants.
e nutritional content and bioavailability of nutrients uctuate season-
ally, and the nutritive qualities of some seaweeds are more benecial at par-
ticular times of the year (Black and Mitchell ; Fleurence ). In Japan,
hijiki (Cystophyllum fusiforme) is gathered in January and February, when
the plants are small and tender, and awonori (Ulva intestinalis) is harvested
between November and April, but miru (Codium spp.) is harvested only in
April and May (Smith a, –). While seaweeds are generally rich in
iodine, concentrations vary among seaweed taxa, through the year, and in
dierent parts of a single organism (Black and Mautner , ; Mitchell
; Smith a, ).
Beyond their nutritional benets, many types of seaweed also have me-
dicinal qualities that aboriginal populations around the world recognize
(Bell , ; Hoppe , ; Mouritsen ). In Peru, mococho (a term
for edible seaweeds) is known as an excellent source of vitamins and is
chewed during the winter to ward o sickness (Bradley ). On islands
o the coast of Chile, seaweed stalks (Durvillaea) are chewed to prevent
goiter, a condition caused by iodine deciency (Chapman , ). Medic-
inal uses of seaweed have also been noted for native peoples of the Pacic
coast of North America, as described below.
 · A. F. Ainis, J. M. Erlandson, K. M. Gill, M. H. Graham, and R. L. Vellanoweth
A D H  S U  P C
Ethnohistoric and modern accounts describe how coastal people around
the globe used seaweeds and seagrasses for food and other purposes. Chi-
nese written records of seaweed use extend back , years (Bell , ;
Xia and Abbott , ). A written source from  BC also demonstrates
ancient Chinese esteem for seaweeds: “Some algae are a delicacy t for the
most honorable guest, even for the king” (Chapman , ). Japanese
written records from around , years ago list sh and seaweeds as im-
portant marine products and items of religious sacrice oered in various
rites (Hoppe and Schmid , ). e written Law of Taiho (AD ) lists
several seaweeds among the items that were paid to the emperors court as
tax. e oldest Japanese-Chinese dictionary, the Wamyo s h o , lists  sea-
weed types used as food during the Heian period (AD –; Nisizawa
et al. , ). In Japan, fragments of sea palm (Eisenia spp.) and Sargassum
have been found in Jomon (– BC) and Yayoi ( BC–AD )
period middens (Nisizawa et al. , ). Seaweeds have been cultivated in
Japanese subsistence economies for centuries, where the traditional gather-
ing of kelp was a seasonal endeavor facilitated by shermen in open boats
using hooks attached to long wooden handles or tied to weighted ropes
and dragged along the ocean oor to pull the weeds from the rocky sea
oor (Chapman , ). Smith (a) described how Ainu (aboriginal
Japanese) collected kelp, noting that women participated in various phases
of drying and processing.
Polynesian cultures also made extensive use of seaweeds, especially the
Hawaiians, who had specic names for the  or so edible species they
gathered. ey used a general term (limu) for seaweeds followed by a de-
scriptive term such as limu lo-loa, the term for a red algae (Gelidium spp.;
MacGaughey , ). e nature of nearshore habitats dictated how sea-
weeds were collected and who collected them. Older women and children
harvested taxa that grew in quiet waters, men and younger women using
stone tools dove for those that grew in rougher waters, and men gathered
species from the outer reef from outrigger canoes (Abbott , ; Mac-
Gaughey , ). On the islands of Austronesia, women and children
appear to be the primary collectors of sea vegetables (Ono , ). In
New Zealand during the early s, the Maori used seaweeds as containers
for oil and other uids and made “horn- or bone-like handles for knives
from the hard bases of Lessonia variegata” (Brooker et al. , ). e
Maori reportedly ate karengo (Porphyra spp.) aer steaming it in earth
Use of Seaweeds and Marine Plants by Native Peoples of Alta and Baja California · 
ovens (Dixon , ) and drank a liquid they made from fermented sea-
weed (Brooker et al. , –). Maoris ate other types of green and red
seaweed in salads and soups. Aboriginal Australians also ate at least two
types of large brown seaweed (Durvillaea) (Chapman , –).
E A  S C 
 P C   A
Along the Pacic coast of North America, native people used seaweed for
food, medicine, and other purposes. ey traded dried seaweeds to in-
land groups who prized their salt content and used them to treat iodine
deciency (Turner , , ; Turner and Loewen ). Other accounts
indicate that seaweeds and seagrasses were harvested as preferred food
sources and used in a variety of ways. Deep cultural ties to special feasts
and etiquette surrounded their consumption (Berlin ; Felger et al. ;
Turner , ).
In Alaska, Nunivak Islanders harvested seaweeds in early April as the
winter ice began to crack (Lantis ). Nelson Islanders gathered seaweed
(Fucus spp.) in late May when herring eggs were attached, eating both to-
gether raw or cooked, and collected kelp for food (Ager and Ager , ).
Historic accounts from the late eighteenth and early nineteenth centuries
describe Kodiak Islanders subsisting on shellsh and “sea cabbage (kelp)”
while on hunting expeditions and during times when other foods were
scarce (Black , ).
Similar practices are described for Northwest coast tribes such as the
Kwakwaka’wakw, the Haida, and the Heiltsuk, who submerged blades
of kelps and eelgrass in advantageous locations to gather herring spawn
(Turner , –; Turner and Bell ). e Haida and other native
groups of the Queen Charlotte Islands and the surrounding area ate green
and red/purple lavers. ey dried lavers and compressed them into blocks
that could be sliced as needed, boiled, and consumed. One account de-
scribes a “very palatable” meal of boiled dulse and halibut (Swan ).
Turner (, ; ) listed red laver (P. abbottae) as the most commonly
consumed seaweed, describing how it was harvested from rocks at low tide
in the early spring, spread out to dry in the sun, then broken into small
pieces and stored. e Haida and Kwakwaka’wakw fermented red laver for
several months before storing seaweed cakes in wooden boxes for winter
consumption. ey also dried and browned laver blades over a re, then
pounded into a powder that could be boiled with water. Turner ()
 · A. F. Ainis, J. M. Erlandson, K. M. Gill, M. H. Graham, and R. L. Vellanoweth
summarized ethnographic accounts of seaweed harvesting as the work of
women, who handled their own canoes and harvested seaweed beds in
cooperative groups.
Eelgrass rhizomes and leaf bases were consumed by the Straits Sal-
ish, the Nuu-chah-nulth, the Kwakwaka’wakw, the Haida, and other
Northwest coast peoples (Turner , –; Turner and Bell ). e
Kwakwaka’wakw valued this resource as “the food of their mythical ances-
tors” and even participated in an eelgrass feast (Turner , ). Eelgrass
rhizomes, stems, and leaf bases were eaten raw, steamed with meats, and
made into cakes that were dried and stored for winter consumption. Surf-
grass (P. scouleri and P. torreyi) was also eaten by some Northwest coast
groups, who formed cakes from the entire plant that contributed to winter
food stores (Turner ).
To the south, the Seri Indians of the Gulf of California in what is now
Sonora, Mexico, consumed eelgrass. Ethnographic accounts indicate that
eelgrass was one of their primary traditional foods, and the many linguistic
terms associated with this resource led researchers to suggest a consider-
able antiquity to this practice (Berlin ; Felger and Moser ; Felger
et al. ; Sheridan and Felger ). Both men and women harvested it
seasonally (late April–early May) in mass quantities, then women and chil-
dren dried, threshed, and removed the fruits, which were toasted or eaten
raw. Toasted fruits were also pounded to open and remove the seeds, which
were ground into our using a mano and metate, then prepared as a gruel
to be eaten with other foods. Accounts from the early s indicate that
native peoples on islands o the coast of Chile consumed large amounts of
sea lettuce and a type of bull kelp (Durvillaea antarctica), which they still
call cochayuyu (Chapman , ).
Although our focus is on the use of marine seaweeds, the use of blue-
green microalgae (Cyanophyta, also known as Spirulina) by Native Ameri-
cans is noteworthy. e protein content of Spirulina constitutes over half of
its dry weight and contains essential amino acids that make it highly prized
as a food supplement. Farrar () described written accounts from as far
back as the mid-s detailing the gathering and consumption of a “very
ne slime” that the inhabitants of Tenochtitlán collected from the surface
of the waters of Lake Texcoco. e Aztecs called this substance tecuítlat
and gathered it seasonally with ne mesh nets when surface deposits were
thickest. e microalga was dried in the sun and made into cakes that kept
well and reportedly tasted like a salty avored cheese.
Use of Seaweeds and Marine Plants by Native Peoples of Alta and Baja California · 
Consumption of Seaweeds along the California Coast
Seaweeds are abundant along the California coast, where Tseng (, )
noted that native peoples had harvested them “for ages, before the advent of
the white man.” Ethnographic sources suggest that several tribes gathered
quantities of kelps and seaweeds and dried them for winter use (Lightfoot
and Parrish , , ). Anderson (, , ) noted that coastal tribes
in California consumed bull kelp, red/purple lavers, and sea lettuce using
sustainable harvesting strategies such as leaving algal holdfasts in place to
support new growth. Lavers were harvested in early spring and dried before
being eaten. e coastal tribes of northern California likely ate sea lettuce
(Baker , ).
Along the central California coast, seaweeds, kelps, and sea palm (Pos-
telsia palmaeformis) were harvested and consumed by some inland groups,
who traveled to the coast primarily to collect them (Lightfoot and Parrish
, ). Various coastal tribes in the area also collected seaweeds for
their salt content and regularly consumed seaweeds as food. e Kashaya
Pomo and coastal Yuki ate the stalks of bull kelp and stalked kelp (Ptery-
gophora californica) aer cooking them on hot ashes, hot coals, or in earth
ovens. Kelps were also cut into strips and dried for storage and later use.
Sea palm was consumed raw or aer cooking in hot ashes or on hot rocks
(Giord , ). e coastal Yuki gathered lavers and dried them in the
sun in the summer, whereas the Kashaya Pomo baked red/purple lavers (P.
lanceolata and P. perforata) for immediate consumption or dried them in
the sun and stored them as large cakes to be baked or fried before being
eaten (Lightfoot and Parrish , –). e coast Miwok collected
seaweeds during low tides, dried them in the sun or near a re, or pounded
them and mixed them with acorn mush.
Although ethnohistoric accounts from the Pacic Northwest to Chile
demonstrate considerable use of seaweeds and seagrasses by native peoples,
accounts of Island Chumash, Tongva, and Huamalgüeño foodways are very
limited. Archaeological data from island shell middens testify to extensive
shing in kelp forests by these island peoples (Erlandson et al. ; Rick et
al. ), but there has been little discussion of seaweeds as a food source.
Timbrook () presented ethnohistoric evidence for Chumash names for
varieties of kelps and seaweeds documented in ethnohistoric literature but
found few references to their consumption. However, living Chumash de-
scendants have described eating giant kelp, bull kelp, and other types of
 · A. F. Ainis, J. M. Erlandson, K. M. Gill, M. H. Graham, and R. L. Vellanoweth
seaweeds in soups or stews (Q. Garcia, pers. comm., ), and the lack of
ethnohistoric descriptions of seaweed consumption may be due to the loss
of traditional knowledge aer more than two centuries of devastating rule
by Spanish, Mexican, and American colonial regimes. e Island Chumash
and Tongva are poorly represented in the ethnographies of California na-
tive peoples, which include only sparse accounts of islander ways and tradi-
tions. Other cultural practices such as songs and dances recorded in ethno-
graphic accounts speak indirectly to the importance of kelps and seaweeds
to indigenous peoples of the California islands. A seaweed dance with ac-
companying paraphernalia was recorded for both the Island Chumash and
their mainland neighbors (Hudson and Blackburn ). In his accounts of
Chumash ritual, Fernando Librado Kitsepawit described several songs for
a seaweed dance performed by people imitating the swaying movements
of kelp or seaweed (Hudson et al. , –). Blackburn (, ) also
noted the use of the Chumash term šutiwiɂyiš for the seaweed dance of
Santa Cruz Island, which was performed along the mainland coast in his-
toric times.
Nonfood Native Uses of Seaweeds and Seagrasses along
the Pacic Coast of North America
e Kwakiutl of British Columbia used the hollow, tubular stipes of bull
kelp to make ropes, harpoon lines, shing lines, shing nets, and vessels
for storing oil (Turner and Bell ). Swan () also described the use of
bull kelp for shing lines to depths of  fathoms, stating that “when wet
it is exceedingly strong, and equal to the best ax or cotton shing lines
of the white sherman.” He also noted that Northwest coast Indians used
the upper hollow portion of the stems as receptacles for oil from marine
mammals and sh. Along the central California coast, the Kashaya Pomo
also made shing cordage from dried kelp strips (Goodrich et al. ,
–). Oral narratives from Fernando Librado Kitsepawit also record
the Chumash use of kelp to anchor their redwood plank boats (tomols)
while shing (Blackburn , ; Hudson et al. ).
Archaeological evidence indicates that surfgrass was extensively used by
coastal tribes of western North America (Scagel ), including the Island
Chumash and the Tongva, to manufacture cordage, nets, basketry, skirts,
roof thatching, storage containers, and other woven items (Connolly et al.
; Heye , –, plate CXXIII; Hudson and Blackburn , ,
; Olson , ; Vellanoweth et al. ). Despite abundant archaeo-
logical evidence for the use of seagrass on the California islands, however,
Use of Seaweeds and Marine Plants by Native Peoples of Alta and Baja California · 
no ethnographic accounts attest to this practice (Hudson and Blackburn
, ). Eelgrass remains have been found in archaeological contexts on
Isla Cedros, where their rhizomes may have been eaten, but the nature of
native use of this resource is uncertain (Fauvelle et al. ). On the other
side of the Baja peninsula, however, the Seri Indians of Sonora harvested
and relied on eelgrass seeds as one of their staple foods and used the grasses
for a variety of purposes (Felger and Moser ).
In addition to being consumed directly, seaweeds are oen used in food
preparation to steam other dietary items. e southern Kwakiutl of Brit-
ish Columbia used rockweed (F. gardneri) fronds to line pits for steaming
clams, berries, and other foods (Turner and Bell , ). e Tipai of
northern Baja California were known to steam abalone by placing them
shell down in the re covered by wet kelp fronds (Hohenthal , ).
Kelps and other seaweeds were also used as medicine by native peoples
of the Pacic coast (Dillehay et al. ). On the Northwest coast, sea-
weeds were used as a heated poultice for aches and pains, particularly by
pregnant women, and for scabs, burns, and swollen feet (Turner and Bell
). Turner (, ) also described seaweed as “good for any kind of
sickness in the stomach or body” and noted its use as a laxative, to relieve
indigestion and heartburn, and as an antiseptic to deter infection and re-
duce swelling. e Kashaya Pomo sucked on dried pieces of stalked kelp
to soothe sore throats and clear away mucus (Lightfoot and Parrish ,
). e Chumash used a bath of hot seawater and boiled seaweed to treat
paralysis and joint disorders (Walker and Hudson , , ).
I S U   A R
While modern and historical uses of seaweeds and marine plants are well
known around the globe, their use is poorly understood archaeologically.
Extensive evidence of indigenous seaweed use around the Pacic Rim pro-
vides a reasonable baseline for arguing that native islanders and coastal
inhabitants of Alta and Baja California also used the rich and diverse sea-
weeds that surrounded them. e potential use of these abundant resources
by ancient coastal peoples has major implications for the perceived margin-
ality of island environments. e nutritional properties of seaweeds from
the Southern California Bight suggest that they would have been an ideal
addition to the diet of California island peoples, who harvested a diverse
array of other marine and terrestrial resources. e great diversity and bio-
mass of marine seaweeds in the bight and surrounding the islands argues
 · A. F. Ainis, J. M. Erlandson, K. M. Gill, M. H. Graham, and R. L. Vellanoweth
against the marginality of these island environments, suggesting instead
that seaweeds and seagrasses added signicantly to the wealth of marine
food, medicine, and technological resources available to island peoples.
Once this possibility is recognized, new methods are needed for detecting
seaweed use in the archaeological record that can be used to test hypotheses
about their signicance in island economies.
e challenges preservation biases pose in the archaeological record are
well recognized. Although seagrasses are sometimes preserved, the iden-
tication of seaweeds in archaeological sites is extremely rare, even more
so than terrestrial oral remains, due to the lack of structural “hard parts”
commonly found in wood or seeds. Wood charcoal is abundant in many
island archaeological sites, as are carbonized macrobotanical remains, both
of which are oen identiable to genus (see Gill , ; Gill and Hoppa
; Reddy and Erlandson ). Other than Gill (), carbonized re-
mains of seaweeds have not yet been reported on the islands, likely due
to their fragile nature and lower likelihood of surviving the carbonization
process. Experimental studies of fresh seaweeds in New Zealand suggest
that some large brown algae such as giant kelp will decompose within four
months, whereas others can take more than a year (Chapman , ). A
dearth of direct evidence for seaweed use in the archaeological record does
not necessarily mean they were not important to coastal foragers in the
past, and we must explore new methods of detection for direct and indirect
Rare exceptions to such preservation problems exist, including a satu-
rated “wet-site” component at the ~,-year-old Monte Verde site in
coastal Chile (Dillehay et al. ). Uncarbonized seaweed fragments were
found at this pre-Clovis site in hearth features and embedded in hut oors,
indicating extensive use of seaweeds. Nine types of seaweed were identied,
including microparticles from three genera found adhering to stone tools,
testifying to their use by some of the earliest inhabitants of the Americas.
is includes the earliest known human use of giant kelp and Sargassum in
the world. Some fragments were found in masticated “quids” mixed with
terrestrial plant remains, suggesting medicinal uses. Others were partially
burned and may have been dried for storage or cooked for consumption.
Desiccated seaweeds have also been found in archaeological sites along Pe-
ru’s hyperarid Andean coast. Seaweed remains were reportedly abundant at
late Preceramic (~– BP) sites in Peru (Bradley , ; Raymond
), and a red algae (Gigartina chauvinii) that is widely consumed in the
region today was found in another site dated to the fourteenth century
Use of Seaweeds and Marine Plants by Native Peoples of Alta and Baja California · 
AD (see Bell , ). e presence of seaweeds in Pacic coast sites of
South America demonstrates that New World peoples used these resources
for , years or more, supporting the coastal migration theory and the
kelp highway hypothesis (Erlandson et al. , ). If these hypotheses
are correct, these early maritime peoples may have carried knowledge of
seaweed use from homelands along the coastlines of northeast Asia and
Beringia. is conjecture implies that the earliest occupants of California’s
islands also recognized the value of seaweeds and seagrasses and their as-
sociated resources.
Along the Alta California coast, it is clear that kelp forest ecosystems and
seaweeds have great antiquity (Steneck et al. ). In exploring the ancient
human use of seaweeds, we should be cautious about projecting modern
distributions, densities, and diversity into the deep past. Changes in climate
and oceanographic conditions (sea surface temperatures, sea level changes,
etc.) during the late Pleistocene and Holocene aected the densities and
distributions of various seaweed taxa (e.g., Dayton ; M. Graham et al.
; M. Graham et al. ; Kinlan et al. ). Sargassum remains were
relatively common at the ~, year old Monte Verde site, for example,
but the genus is relatively scarce along the west coast of South America to-
day (Dillehay et al. ). Historically, the introduction of invasive species
has also altered the composition of seaweed communities worldwide (i.e.,
Williams and Smith ). If we can learn to more eectively identify sea-
weed remains in archaeological sites, however, the resulting data can enrich
our knowledge of changes in the distribution of various taxa through the
Macrobotanical Remains: Carbonized and Desiccated Seaweeds
For terrestrial plants, carbonization generally increases the likelihood that
remains will preserve archaeologically, but it is not clear if this is true for
seaweeds. Excavations in Scotland have uncovered examples of carbon-
ized “vitreous slag” identied as burnt seaweeds through chemical analysis
(Photos-Jones et al. ). Analysis suggested that seaweed was used to
wrap human bodies for cremation. is practice takes advantage of the
gelatinous nature of seaweeds, which makes them a formidable binding
agent that keeps the bones and ash together during the cremation process.
On the Scottish islands of Orkney and Shetland, carbonized materials from
two Norse sites were also tentatively identied as burnt seaweeds, including
specimens with characteristics typical of bladder wrack (Fucus vesiculosus)
(Bell , ).
 · A. F. Ainis, J. M. Erlandson, K. M. Gill, M. H. Graham, and R. L. Vellanoweth
Figure .. Fragments of desiccated marine algae from archaeological deposits in a sea
cave on Santa Cruz Island (CA-SCRI-) that has recently been dated to the Late period
(excavations by J. Erlandson and K. Gill, photo by K. Gill).
e use of dried seaweeds and seagrasses as fuel, roong, and matting
has been extensively documented around the world (McRoy and Helerich
, –; Mouritsen , –). Seaweeds may have been used in
these ways on islands, given their abundance and the sometimes limited
tree and shrub fuel sources in these habitats. Photos-Jones et al. () have
described burnt seaweed fused with sand that resembles small fragments
of vitreous materials and may be confused with asphaltum fragments with
embedded sand, which are common in California island middens. Prelimi-
nary comparative studies of burnt Channel Island seaweeds and samples
of “vitreous slag” found in archaeobotanical samples from island middens
used electron microscope images to suggest that carbonized seaweeds may
be common in some middens (K. Gill, pers. comm. ). Further mi-
croscopic and chemical analyses may help conrm whether these vitreous
materials are seaweed residues, identify various types of seaweeds, and de-
termine if they were used for food, fuel, or other purposes.
Uncarbonized seaweed remains can occasionally preserve in saturated
or hyperarid conditions such as Monte Verde and the Andean coast of Peru.
As we have become more aware of seaweeds as potentially signicant ma-
rine resources, we have become more sensitive to identifying them in Cali-
fornia island shell middens. Recent excavations by Erlandson and Gill at
a coastal cave site on Santa Cruz Island dated to around AD  revealed
uncarbonized and desiccated fragments of several types of seaweed and
Use of Seaweeds and Marine Plants by Native Peoples of Alta and Baja California · 
kelp that were preserved because of exposure to regular sea spray (Figure
.). ese have yet to be identied, but their presence suggests that desic-
cated seaweed remains may be recoverable in some contexts even where
sediments are not fully saturated or are completely dry. Uncarbonized and
desiccated terrestrial plant remains (i.e., tobacco seeds) were also recovered
from this site, pointing to the extraordinary preservation that occurred at
this site (see Gill ).
Microbotanical Remains: Phytoliths, Starches, Isotopes, and Diatoms
Other promising approaches to documenting seaweed use by ancient
coastal peoples involve the identication of various microbotanical re-
mains, including phytoliths, starches, isotopes, and diatoms. Golokhvast
et al. () has demonstrated that both red and brown algae from the Sea
of Japan contain phytoliths. According to Synytsya et al. (), marine
algae also contain cell wall polysaccharides (starches) that vary depend-
ing on taxon, anatomical part, life-cycle stage, and season/habitat. ese
polysaccharides can be good taxonomic markers. e cell walls of red and
brown algae also have specic structures composed of cellulose brils that
could be identiable archaeologically. In Japan and the Pacic Northwest,
seaweeds were dried and ground into a powder that was added to foods
(Smith a, ; Turner , ). Such preparation techniques suggest
that residue analysis (including chemical, phytolith, and/or polysaccharide
residues) of ground stone tools, cooking vessels, dental calculus, hearths,
and soils might be fruitful avenues of research for identifying seaweed con-
sumption in the past. To our knowledge, no such analyses have been at-
tempted in Pacic coast shell middens, nor are we aware of the existence of
collections that would be necessary for comparison. It seems worth the ef-
fort, however, to document the nature of phytoliths in some abundant kelps
and seaweeds from the region and to check promising midden samples for
their presence.
Indirect Evidence: Associated Mollusks
Several researchers have shown that indirect archaeological evidence for
seaweed use can come from the identication of mollusks associated with
seaweed. Rowland (, ) suggested that small “uneconomic shells”
might have been brought to archaeological sites as attachments on har-
vested marine plants. Mollusks that are known to be seaweed commensals
that have been identied in archaeological assemblages along the Mediter-
ranean coast have been used to imply that Upper and Lower Paleolithic
 · A. F. Ainis, J. M. Erlandson, K. M. Gill, M. H. Graham, and R. L. Vellanoweth
peoples transported seaweeds to cave sites (Barrière ; Colonese and
Wilkens ). Bell (, ) used small marine mollusk commensals and
bryozoans to argue for seaweed exploitation in a multicomponent site dat-
ing from the early Iron Age to the pagan Saxon period on Great Britain’s
Sussex coast, although no seaweed fragments were preserved at this site. To
indirectly demonstrate seaweed use in the past, Bell () collected sam-
ples of several seaweed species o the beach and dissected the holdfasts,
fronds, and stipes for materials that would potentially preserve in archaeo-
logical contexts. He identied ve bivalves, six gastropods, and barnacles,
bryozoans, foraminfera, polychaetes, and gravels that may be associated
with transportation of seaweeds to habitation sites.
At two shell middens from California’s Channel Islands, analysis of
shellsh remains identied  types of small gastropods (n = ,) associ-
ated with seaweeds and seagrasses (Ainis et al. ). Additional species
of commensals inhabit Channel Island kelp forests (see Coyer ; Gra-
ham ; North , –) and may be used to identify kelp or seaweed
use. e analyzed Channel Island sites include multiple rock-shelter and
open-air components spanning much of the past , years. Roughly 
percent of the nondietary mollusks at both sites were identied as seaweed
and seagrass associates; various strata and features contained higher or
lower densities. e number and diversity of these incidental gastropods
associated with seaweeds and seagrasses points to the likelihood that na-
tive islanders imported and used these perishable resources throughout
the Holocene. In the future, we hope that archaeologists working on the
California islands and in coastal sites around the world will more closely
examine shellsh taxa from shell middens for indirect evidence of seaweed
and seagrass harvesting.
Another avenue for potentially identifying seaweed remains in archaeo-
logical deposits is the identication of diatoms, some species of which are
primarily associated with various seaweed taxa (Edgar ). is would
potentially treat diatoms as indirect markers of seaweed gathering and use
that may be detectable through scanning electron microscope imaging or
other high-powered microscopic analysis. Small otherwise unidentiable
fragments of seaweed may be recognized through the identication of cer-
tain diatom species adhering to them. Alternatively, in the absence of pre-
served fragments, the presence of specic diatoms in archaeological soil
deposits could serve as indirect markers of seaweed at the site.
Use of Seaweeds and Marine Plants by Native Peoples of Alta and Baja California · 
In this chapter, we explored the biology, ecology, diversity, distribution,
and nutritional content of seaweeds and marine plants along the Pacic
coast of North America, focusing on the Southern California Bight and the
islands of Alta and Baja California. We documented that coastal peoples
used seaweeds throughout the Pacic region for food, medicine, and a va-
riety of technological purposes. Historical accounts document the use of
seaweeds as food for at least , years in East Asia and archaeological
records show that populations along the Chilean coast of South America
used seaweeds for culinary and medicinal purposes beginning around
, years ago. Ethnohistoric accounts demonstrate that native peoples
of the Pacic Northwest and California coast used seaweeds for food and
other purposes; these practices likely extend much earlier in time.
In contrast, ethnohistoric and archaeological evidence for the use of
kelps and seaweeds by the Island Chumash, Tongva, and Huamalgüeños
is sparse. While a preservation bias exists, archaeological evidence for sea-
weed use in the Southern California Bight may have been there all along.
Archaeologists, however, must confront the challenges involved in nd-
ing evidence for seaweed use and recognize why there may be a dearth
of ethnohistoric evidence pertaining to islanders. While the ethnohistoric
record is largely silent about the use of seagrasses, archaeological evidence
for their use is relatively abundant in the region. In both cases, the lack of
ethnohistoric records for the use of seaweeds and kelps on these islands
reects the devastating eects of European contact on island peoples of the
California Bight rather than an absence of use by maritime peoples with a
deep history of intensive maritime adaptations.
Because scores of edible seaweed species inhabit the waters around Cali-
fornia’s islands—rich in carbohydrates, essential fatty acids, and other key
nutrients—it is increasingly dicult to characterize the islands as marginal
habitats for human occupation. An incredible wealth of marine mammals,
sh, shellsh, and birds rich in protein and fats; abundant geophytes and
other terrestrial plants rich in carbohydrates; and a plethora of edible sea-
weeds were available to island populations as either staples or backup foods
in times of stress. Because of this, it is likely that starvation was nearly im-
possible, even with population increases later in time. As archaeological,
genomic, and other support grows for a coastal dispersal from northeast
Asia into the Americas following a Pacic Rim kelp highway route, it also
seems likely the rst Americans were maritime peoples who entered the
 · A. F. Ainis, J. M. Erlandson, K. M. Gill, M. H. Graham, and R. L. Vellanoweth
New World with a detailed knowledge of coastal ecosystems and the sea-
weeds that were abundant in them.
Although the signicance of seaweeds and marine plants to the earliest
coastal peoples on the California islands remains hypothetical for now, new
scientic methods are emerging that may allow archaeologists to evalu-
ate the importance of seaweeds in the indigenous maritime economies of
the Pacic coast of the Americas. e challenge now is for archaeologists
to search for the evidence needed to conrm or refute the idea that kelp
forests, seaweeds, and other marine plants were important resources that
helped attract maritime peoples to the islands of Alta and Baja California
and to sustain large populations of their descendants for millennia.
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... In Italy, small gastropods of the species Jujubinum exasperatus have also been interpreted as an indirect indicator of alga extraction and deposition in archaeological sites (Colonese and Wilkens, 2005). Finally, in Baja California, Mexico, and the Californian coast of the United States, Ainis et al. (2014); Ainis et al. (2019) conducted studies on small archaeo-malacological fauna, which, due to their small size, are believed not to be collected for food purposes. One type of these small-sized mollusks corresponds to species associated with algae and seagrasses (Ainis et al., 2014). ...
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Coastal societies have lived at the seaward edge of the Atacama Desert since at least 12,000 years ago. Kelp forest ecosystems provide evidence for important subsistence activity along the entire Chilean coast through fishing and gathering. Despite their importance, especially in hyperarid contexts with limited plant abundance, there is scarce evidence of kelp in archaeological contexts, hampering the study of kelp use in the past. In the present study, we use the presence of small marine invertebrates, inhabitants of stipes and holdfasts of macroalgae, as proxies that indicate past kelp presence. We analyze samples of three species of snails (Tegula atra, Tegula tridentata, and Diloma nigerrima) and one limpet (Scurria scurra) from nine archaeological sites dated between 7,000 and 500 cal years before present located around the area of Taltal (25°Lat S). Modern samples of these species were collected to reconstruct the size of fragmented archaeological shells and subsequently estimate the size of harvested kelps. Through this approach, we estimated the size and relative abundance of kelp used by coastal groups that inhabited the southern part of the Atacama Desert for around 6,500 years. Our results are a contribution to the scarce information on the presence and use of kelp in the prehistory of the Americas and contribute to comparative perspectives with other areas of the world where the use of kelp by humans in the past has already been explored.
... It is suggested that marine algae and plants have been harvested by human groups as bedding material and fuel for fires (de Lumley et al., 2004) or as food resourcesroughly 150 species of seaweeds are considered edible with some species boasting mineral contents higher than many land plants (Kumar et al., 2008). Additionally, ethnobotanical studies reveal substantial and varied uses of marine plants (both living and dead) by traditional coastal communities worldwide, including the production of cordage, nets, basketry and medicine (Scagel, 1961;Turner and Bell, 1973;McRoy and Helfferich, 1980;Connolly et al., 1995;Vellanoweth et al., 2003;Mouritsen, 2013;Milchakova et al., 2014;Ainis et al., 2019). ...
... Although previous work has studied automatic or semi-automatic segmentation and classification of eelgrass (Z. marina) from drone-based data [16][17][18]32], this study is the first to our knowledge to evaluate the application of deep learning methods for this task. This is also the first study to our knowledge to evaluate automatic eelgrass delineation in the California Current at a high-resolution scale on the order of cm. ...
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Shallow estuarine habitats are globally undergoing rapid changes due to climate change and anthropogenic influences, resulting in spatiotemporal shifts in distribution and habitat extent. Yet, scientists and managers do not always have rapidly available data to track habitat changes in real-time. In this study, we apply a novel and a state-of-the-art image segmentation machine learning technique (DeepLab) to two years of high-resolution drone-based imagery of a marine flowering plant species (eelgrass, a temperate seagrass). We apply the model to eelgrass (Zostera marina) meadows in the Morro Bay estuary, California, an estuary that has undergone large eelgrass declines and the subsequent recovery of seagrass meadows in the last decade. The model accurately classified eelgrass across a range of conditions and sizes from meadow-scale to small-scale patches that are less than a meter in size. The model recall, precision, and F1 scores were 0.954, 0.723, and 0.809, respectively, when using human-annotated training data and random assessment points. All our accuracy values were comparable to or demonstrated greater accuracy than other models for similar seagrass systems. This study demonstrates the potential for advanced image segmentation machine learning methods to accurately support the active monitoring and analysis of seagrass dynamics from drone-based images, a framework likely applicable to similar marine ecosystems globally, and one that can provide quantitative and accurate data for long-term management strategies that seek to protect these vital ecosystems.
... Early Holocene coastal and island populations would have had access to abundant marine resources, with faunal assemblages at locations such as Eel Point on San Clemente Island and Daisy Cave on San Miguel Island containing shellfish, finfish, and pinniped remains (Gusick et al., 2020;Rick et al., 2001). Island populations would also have exploited numerous marine and terrestrial floral resources including seaweeds and geophytes (Ainis et al., 2019;Gill, 2016), while mainland populations increased their consumption of seeds, agave, and other terrestrial plants throughout the Early Holocene (Erlandson, 1991;Jones, 2008). ...
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Understanding how maritime hunter-gatherer diets changed through time in response to increasing social complexity can help us understand important transitions in early human history. This paper presents new baseline stable isotope values for southern California with an emphasis on marine plant and animal species. We use our baseline database to reevaluate human stable isotope values from the region using Bayesian mixing models to interpret dietary patterns across time and geographic space. Our analysis compares categories of foods consumed between island, coastal, and interior populations across the Middle and Late Holocene (circa 8000 to 168 cal BP) occupational history of precolonial southern California. Our results show a clear increase in the importance of high trophic marine foods, such as finfish, relative to low trophic level food, such as shellfish through time, paralleling increases in population size, economic intensification, and village aggregation in the Channel Region. This case study displays the capacity of Bayesian modeling to infer patterns of dietary change in the past when applied to human isotope values and adds to previous studies on the relationship between population growth, technological innovation, and the intensification of resource extraction in the region.
... The latest reconstructions of Santarosae's paleogeography suggest that rising post-glacial sea level reduced the landmass by as much as 70-75 percent, causing the NCI to separate between about 11,000 and 9,000 years ago [13,14]. Then and now, the NCI had a relatively impoverished terrestrial fauna, a fairly diverse and productive flora, and a wealth of edible marine resources, from seaweeds to marine mammals, shellfish, fish, and seabirds [15,16]. ...
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During the last 10 years, we have learned a great deal about the potential for a coastal peopling of the Americas and the importance of marine resources in early economies. Despite research at a growing number of terminal Pleistocene archaeological sites on the Pacific Coast of the Americas, however, important questions remain about the lifeways of early Paleocoastal peoples. Research at CA-SRI-26, a roughly 11,700 year old site on California's Santa Rosa Island, provides new data on Paleoindian technologies, subsistence strategies, and seasonality in an insular maritime setting. Buried beneath approximately two meters of alluvium, much of the site has been lost to erosion, but its remnants have produced chipped stone artifacts (crescents and Channel Island Amol and Channel Island Barbed points) diagnostic of early island Paleocoastal components. The bones of waterfowl and seabirds, fish, and marine mammals, along with small amounts of shellfish document a diverse subsistence strategy. These data support a relatively brief occupation during the wetter "winter" season (late fall to early spring), in an upland location several km from the open coast. When placed in the context of other Paleocoastal sites on the Channel Islands, CA-SRI-26 demonstrates diverse maritime subsistence strategies and a mix of seasonal and more sustained year-round island occupations. Our results add to knowledge about a distinctive island Paleocoastal culture that appears to be related to Western Stemmed Tradition sites widely scattered across western North America.
... The latest reconstructions of Santarosae's paleogeography suggest that rising post-glacial sea level reduced the landmass by as much as 70-75 percent, causing the NCI to separate between about 11,000 and 9,000 years ago [13,14]. Then and now, the NCI had a relatively impoverished terrestrial fauna, a fairly diverse and productive flora, and a wealth of edible marine resources, from seaweeds to marine mammals, shellfish, fish, and seabirds [15,16]. ...
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Gracilaria chilensis is the main cultivated seaweed in Chile. The low genetic diversity observed in the Chilean population has been associated with the over‐exploitation of natural beds and/or the founder effect that occurred during the post‐glacial colonization from New Zealand. How these processes have affected its evolutionary trajectory before farming and incipient domestication is poorly understood. In this study, we used 2,232 SNPs to assess how the species evolutionary history in New Zealand (its region of origin), the founder effect linked to transoceanic dispersion and colonization of South America, and the recent over‐exploitation of natural populations have influenced the genetic architecture of G. chilensis in Chile. The contrasting patterns of genetic diversity and structure observed between the two main islands in New Zealand attest to the important effects of Quaternary glacial cycles on G. chilensis. Approximate Bayesian Computation analyses indicated that Chatham Island and South America were colonized independently near the end of the Last Glacial Maximum and emphasized the importance of coastal and oceanic currents during that period. Furthermore, ABC analyses inferred the existence of a recent and strong genetic bottleneck in Chile, matching the period of over‐exploitation of the natural beds during the 1970s, followed by rapid demographic expansion linked to active clonal propagation used in farming. Recurrent genetic bottlenecks strongly eroded the genetic diversity of G. chilensis prior to its cultivation, raising important challenges for the management of genetic resources in this incipiently domesticated species.
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Sea urchins, one of the few echinoids harvested for human consumption, are found in archaeological sites from coastal settings around the world spanning at least the past ∼15,000 years. Sea urchin tests and spines are commonly found in archaeological shell middens on California’s Channel Islands, sometimes forming dense “urchin lenses.” Though ubiquitous, the fragile nature of their test (outer shell) results in a high degree of fragmentation, complicating identification and quantification in archaeological assemblages. I discuss issues regarding archaeological sea urchin remains off the coast of western North America and present a method for estimating the sizes of harvested purple (Strongylocentrotus purpuratus) and red (Mesocentrotus franciscanus) sea urchins through allometry, allowing archaeologists to configure size/age estimates for harvested populations in the past. These methods are applied to two archaeological assemblages from San Nicolas and San Miguel islands, revealing evidence of a potential urchin proliferation event in the California Bight during the late Middle Holocene, and relative consistency in the primary types and sizes of harvested specimens through time. As a keystone species dominating ecological interactions in kelp forest ecosystems, sea urchin remains can provide deep historical perspective on the relative state of intertidal ecosystems.
As the smallest of California’s Channel Islands, Santa Barbara Island has received limited attention from archaeologists. A United States National Park Service project designed to assess its 19 known sites evolved into an island-wide survey that increased the number to 63 sites that date between 4000 and 600 years ago. Most are small shell and lithic scatters, although some are larger shell middens with greater faunal and artifact diversity. Their constituents and geographic distribution indicate that the island not only served as a stopover during inter-island travel but was occupied for longer periods to target local resources such as marine mammal rookeries. Our research presents an opportunity to evaluate the significance of this island to prehistoric communities throughout the archipelago. On a broader level, it provides insights into the important roles that small islands have played in prehistoric lifeways as well as perceptions of marginality.
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Ethnobotany of the Yurok, Tolowa, and Karok Indians of northwest California, including original ethnographic data obtained from individuals of these cultures. The uses of vascular and non-vascular plants by these peoples are discussed, as well as signicance of their plant names with respect to folk taxonomy.
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We synthesize northern Channel Islands archaeobotanical data to discuss broad, diachronic patterns in ancient plant use. Using quantitative and qualitative comparisons, we explore the relative importance of plant foods through time and consider how plant food rankings on the islands may have differed from those on the mainland. We argue that geophytes were the highest ranked plant food resource, valued for their contribution of easily procured carbohydrates in an island environment rich in marine protein and fat resources. Geophytes are phenomenally abundant on the islands, and were used consistently by the Island Chumash and their ancestors for at least 10,000 years with no significant change through time. We also explore the representation of various other plant foods through time and consider what archaeobotanical data indicate about the use of grindstone, division of labor, and island-mainland exchange networks.
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Seaweeds or macroalgae have been a source of food, feed and medicine in the orient as well as the West since ancient times. Being plants of unique structure and biochemical composition, seaweeds could be exploited for their multifunctional properties. They are sources of useful bioactive components like phycocolloids, proteins, vitamins, minerals, carotenoids like fucoxanthin and n3 fatty acids, which are known to possess nutritional value apart from their potential biomedical applications. The present review highlights the various bioactive materials of seaweed origin and their potential applications.
Capturing the vitality of California's unique indigenous cultures, this major new introduction incorporates the extensive research of the past thirty years into an illuminating, comprehensive synthesis for a wide audience. Based in part on new archaeological findings, it tells how the California Indians lived in vibrant polities, each boasting a rich village life including chiefs, religious specialists, master craftspeople, dances, feasts, and ceremonies. Throughout, the book emphasizes how these diverse communities interacted with the state's varied landscape, enhancing its already bountiful natural resources through various practices centered around prescribed burning. A handy reference section, illustrated with more than one hundred color photographs, describes the plants, animals, and minerals the California Indians used for food, basketry and cordage, medicine, and more. At a time when we are grappling with the problems of maintaining habitat diversity and sustainable economies, we find that these native peoples and their traditions have much to teach us about the future, as well as the past, of California.