Brown+Algae

7/27/2019 Brown+Algae

1/7

Brown AlgaeChristopher E Lane, Dalhousie University, Nova Scotia, Canada

Gary W Saunders, University of New Brunswick, Fredericton, Canada

Brown algae form a natural class, the Phaeophyceae, including c. 265 genera with 15002000 species. They form rich underwater forests along much of the cold and temperate

coastlines of our planet.

Introduction

Brown algae (Figure 1) form a natural class, the Phaeophy-ceae, including c. 265 genera with 15002000 species (vanden Hoek et al., 1995). They belong to a larger algal as-semblage collectively termed the heterokont chromo-phytes. Chromophyte refers to the plastid shared by theselineages, which has four bounding membranes, the pig-

ments chlorophyll a and c and various accessory pigmentsincluding fucoxanthin, which imparts the brown colour tothe Phaeophyceae. Heterokont refers to the flagellar ar-rangement associated with motile cells; the leading flag-ellum is characterized by two rows of stiff mastigonemesand the trailing flagellum is smooth. Vegetative stages forother heterokont chromophyte classes are predominantlyflagellate or coccoid unicells and colonies. Brown algalflagellate stages are confined to the reproductive gametesand spores, whereas vegetative stages are exclusively mul-ticellular (Figure 1), ranging from microscopic filaments tofoliose plants up to 50 m in length and 300 kg in weight(Laminariales). Brown algae are, therefore, generally dis-

cussed in reference to their ecological and morphologicalequivalents, those marine members of the Chlorophyta(green algae) and Rhodophyta (red algae) collectivelytermed seaweeds. See also: Algal flagella; Green algae

Morphology and Anatomy

The simplest brown algae have a heterotrichous organiza-tion consisting of a prostrate filamentous system giving riseto free branched or unbranched erect filaments (Figure 1b).Additional haplostichous (filamentous construction)forms include loose aggregates of filaments enclosed in

common mucilaginous mass, solid pseudoparenchy-matous aggregations of filaments producing crusts(Figure 1c) and branched or unbranched terete and folioseplants. Polystichous construction (cell divisions in manyplanes to yield true parenchyma) produces terete to foliosethalli in some species (Figure 1dj). Brown algae display thegreatest anatomical complexity among the protists. Cellshave cytoplasmic continuity via plasmodesmata (analo-gous to land plant structures) and in the orders Lamina-riales and Desmarestiales specialized cells (trumpet

hyphae) form cellular pipelines within the thallus for thdistribution of photosynthetic product.

Growth may be diffuse (i.e. cell divisions occur throughout the plant), or concentrated in meristems that can b

intercalary, trichothallic (intercalary meristem positioneat the base of a terminal filament), or apical from a singlcell, group of cells or plant margins. In some species, a superficial layer of meristematic cells, the meristoderm, contributes to growthby adding cells to theepidermis,as well atowards the thallus interior contributing to plant girth.

Cell Structure

Vegetative cells (Figure 2) are surrounded by a wall of celulosic microfibrils reinforced by insoluble alginates (e.g

calcium alginate). This structural portion of the wall iembedded in an amorphous mucilaginous componen(soluble alginates and the sulfated polysaccharide fucodan). The plasma membrane lies beneath the wall, encircling the cytoplasm and is continuous between cells viplasmodesmata. Organelles consistent with typical phototrophic eukaryotes are present: a nucleus, with one or mornucleoli, surrounded by the nuclear endoplasmic reticulum(NER) which is continuous with the cytoplasmic ER; mitochondria and Golgi bodies, commonly positioned adjacent to the NER. There are a few ribbon-shaped tnumerous discoid plastids that are surrounded by a twomembrane chloroplast ER (CER), the latter continuou

with the NERwhereplastids liein proximity to the nucleuInside the CERis the two-membrane chloroplast envelopthe compartment between these two double-membransystems containing periplastidial ER. Lamellate thylakoids generally occur in stacks of three with one stacoccupying the periphery of the plastid (girdle lamellaeThe plastid deoxyribonucleic acid (DNA) is concentratein a ring-shaped genophore. Pyrenoids (PY) occur isome brown algal plastids and are protuberant, often having a stalked appearance. The major carbohydrate reserv

Article Contents

Advanced article

. Introduction

. Morphology and Anatomy

. Cell Structure

. Life Histories

. Major Groups

. Palaeontology

. Ecology

. Economic Significance

doi: 10.1038/npg.els.000425

ENCYCLOPEDIA OF LIFE SCIENCES & 2006, John Wiley & Sons, Ltd. www.els.net


2/7

Figure1 Morphological diversityamong brown algae. (a) Epilithiccarpet of intertidalbrown algae. (b) Pilayella littoralis: filamentous brown(scale 1 cm

(c) Ralfsia fungiformis: crustose representative (scale 2 cm). (d) Laminaria saccharina: a kelp (scale 10 cm). (e) Alaria nana: a kelp with sporophylls (rulercm). (f) Postelsia palmaeformis: a member of the Lessoniaceae (scale 11cm). (g) Macrocystis integrifolia: a giant kelp; inserts (left to right) holdfast,sporophyll,region of blade production. (h) Hormosira banksii: a southernhemisphere fucoid(scale 3 cm). (i)F. spiralis: a high intertidal fucoid(scale 3 cm

(j) F. distichusssp. edentatus: a low intertidal inhabitant (scale 2.5 cm) with a close-up (k) of developing receptacles and their characteristic conceptacl(scale 1 cm). The author graciously acknowledges the assistance of Mr Roger Smith (University of New Brunswick) in production of this figure.

Brown Algae

2


3/7

laminarin, is soluble and stored in cytoplasmic vacuolescommonly positioned adjacent to the CER where the PY isformed. Brown algal cells contain special vesicles calledphysodes (discussed below). See also: Algal cell walls;Algalchloroplasts

Life Histories

Alternation of generations, i.e. a free-living diploid sporo-phyte alternates with an independent haploid gametophyte,

is the rule for brown algae and can be isomorphic or heteromorphic (generations appear similar (Figure 3a) or differen(Figure 3b), respectively). Meiosis (R!) occurs in uniloculasporangia, resulting in the production and release of meiospores, whereas the mitotic production of gametes and asexual mitospores, usually occurs in plurilocular structuretermed gametangia and sporangia, respectively. Isogamy

anisogamy and oogamy are observed for different speciesSee also: Gametophyte and sporophyte

Major Groups

Brown algae are traditionally separated into orders on thbasis of life history pattern, type of growth and thallustructure, number and type of plastid and whether or nopyrenoids are present. As in all algal groups, this systemof classification is being revised as a result of moleculasystematics. As many as 16 orders have been recognize(see van den Hoek et al., 1995 for detailed descriptionsbut consensus is lacking and schemes with fewer orders arrecognized (Druehl et al., 1997; Rousseau et al., 2001Draisma et al., 2001). Five of these orders are discussedSee also: Algal taxonomy: historical overview

Ectocarpales

A cosmopolitan order with epilithic, epiphytic or partiallendophytic species reported, the Ectocarpales has beeconsidered the most primitive group of brown algae baseon its filamentous morphology. Taxonomic revisions, considering both the affinities of the Ectocarpales relative t

other brown algae orders (Rousseau et al., 2001; Draismet al., 2001) and the generic composition of this orde(Rousseau and de Reviers, 1999), have been recommendein light of recent molecular investigations. We present herthe Ectocarpales sensu Rousseau and de Reviers (1999including only taxa possessing exserted, pedunculatepyrenoids.

PY

CERCEPER

NER

CW

PH

CH

CH*GONU

N

G

G

CV ER

MPH

PL PM

T

Figure 2 Schematic diagram of vegetative cell anatomy. CW, cell wall;

PM, plasma membrane; PL, plasmodesmata; NU, nucleus; N, nucleolus;NER, nuclear endoplasmic reticulum; ER, endoplasmic reticulum; M,mitochondria; GO, Golgi body; CH, discoid plastid; CER, chloroplast

endoplasmic reticulum; CE, chloroplast envelope; PER, periplastidialendoplasmic reticulum; T, thylakoid; G, gonophore; PY, pyrenoid; CV,cytoplasmic vacuole; PH, physode. The anatomy of one plastid (CH) was

not elaborated. Based on information from van den Hoek et al. (1995).

Meiospores

Sporophyte

Unilocularsporangium

R! Pluriloculargametangia

Malegamete

Zygote

Syngamy Femalegamete

Gametophyte(a)

Sporophyte

(b)

Youngsporophyte

Syngamy

Egg

Gametophyte

Malegamete

Unilocularsporangium

R!

Meiospores

Oogonium

Antheridium

Figure 3 Common life history types. (a) Isomorphic pattern typical of some Ectocarpales. (b) Heteromorphic pattern of the Laminariales. See text fodetails. R!, meiosis.

Brown Algae


4/7

Vegetative thalli (Figure 1b) consist of branched uniseri-ate filaments. Thalli are heterotrichous with filaments ofthe prostrate base growing by apical division. Intercalarydivisions occur in the erect filaments and can be dispersedor concentrated in meristems.

Isomorphic alternation of generations is prevalent(Figure3a). Gametes are formed in plurilocular gametangia

on the haploid gametophytes. Morphological similarity(isogametes) belies the true complexity of these gametes,which commonly display behavioural anisogamy, i.e. fe-male gametes settle soon after release and emit pherom-ones that attract the male gametes. Fusion results in adiploid zygote that grows into the sporophyte. Sporo-phytes produce unilocular sporangia in which meiosis (R!)and subsequent mitoses occur to produce numerous motilehaploid meiospores that will develop into male and femalegametophytes. Plurilocular structures can occur on spor-ophytes, but in this case they produce diploid spores bymitosis that regenerate the sporophyte generation.

Dictyotales

A mostly tropical order exhibiting erect, parenchymatousthalli and an isomorphic alternation of generations.Growth is from either an apical cell, or a meristematicmarginal row of cells. The modification of the unilocularsporangia in the Dictyotales, which divide to produce fourto eight aplanospores, is unique among brown algae. Ad-ditionally, while oogomous sexual reproduction is not un-usual among brown algae, members of the Dictyotales arethe only members of the Phaeophyceae to have uniflagel-late sperm (a second basal body is present).

Like the Ectocarpales, the accepted phylogenetic posi-tion of the Dictyotales within brown algae has changedwith the application of molecular data. Long thought to beone of the most derived orders of brown algae, moleculardata indicate that the Dictyotales branched off prior to theancestral line that gave rise to the majority of brown algalorders and is thus only a distant relative to these lineages(Rousseau et al., 2001; Draisma et al., 2001).

Desmarestiales

Species included in this order are common inhabitants incolder waters of all oceans and form the dominant com-

ponent of the subtidal flora in the Antarctic region. Theirlife histories are similar to the Laminariales type (Figure3b).Growth of the dominant sporophyte is from a trichothallicmeristem with pseudoparenchyma developing below themeristem. This basic construction is augmented in somespecies by activity of a meristoderm contributing paren-chyma to the thallus. Gametophytes are microscopic andfilamentous with separate males and females producingantheridia and oogonia, respectively, rather than plurilo-cular gametangia.

Species of the largest genus in this order, Desmarestiaare roughly divided into three groups (Peters et al., 1997Two of these are present in North America represented balternately branched perennials and oppositely brancheannuals. In the oppositely branched species, sulfuric acidpresent in vacuoles. Care in collecting these species is necessity because if they are stored with other samples the

will rapidly destroy, in addition to themselves, the spoils oan entire collecting trip!

Laminariales

Collectively referred to as kelp, these algae form extensivstands in the cold waters of the northern hemisphere iboth the Atlantic and Pacific Oceans, reaching their cumination in the luxuriant kelp forests of the northeast Pacific. There have also been sporadic introductions to thsouthern hemisphere, possibly during recent cooling even(Druehl et al., 1997).

Kelp have a strongly heteromorphic alternation of generations (Figure 3b). The dominant sporophytes lend thkelp their distinction as the largest seaweeds and are folioswith a characteristic morphology and anatomy. Plants aranchored by a disc-like, rhizoidal or branched (hapteralholdfast positioned below a distinct stem-like stipe in mospecies, which is crowned by a blade (Figure 1dg). In somspecies there are specialized blades,termed sporophylls, owhich unilocular sporangia are produced, and some species have numerous blades resulting from splitting at thstipe to blade transition zone.

Six families are currently recognized within the Laminariales, three considered ancestral (Akkesiphycacea

Chordaceae and Pseudochordaceae (Kawai and Sasak2000; Sasaki et al., 2001) and three derived (AlariaceaeLaminariaceae and Lessoniaceae). Traditionally, the taxonomy of the derived families has been based on the preence (Alariaceae: Figure 1e) or absence of sporophylls, anfor the latter case the presence (Lessoniaceae: Figure 1fgor absence (Laminariaceae: Figure 1d) of splitting. Somspecies, however, display characteristics of two familie(e.g. Macrocystis integrifolia, with splitting and sporophylls, Figure 1g) and this system of taxonomy has beefurther compromised by molecular investigations (Druehet al., 1997; Yoon et al., 2001), which clearly show polyphyly among the three traditional families.

Growth of sporophytes is from an intercalary meristemand associated meristoderm positioned at the stipe-toblade transition zone. Some species are annuals growing amuch as 36 cm per day, whereas other species are perennial, with life expectancies of 317 years. The resultinplants have parenchymatous construction with tissue specialization unequalled among algae. Notably, elongatcells with flared ends at the crosswalls (termed trumpehyphae because of their morphology) form long tractof conducting tissue within the medulla. Crosswalls ar

Brown Algae

4


5/7

traversed by numerous plasmodesmata, which can formrelatively wide connections in larger species, developingthe appearance of sieve plates in the phloem of land plants.The analogy to phloem goes further because it has beenestablishedthat trumpet hyphae facilitate the movement ofphotosynthetic product within kelp (Schmitz, 1981).

The gametophyte bears no resemblance to the spor-

ophyte and is more reminiscent of an ectocarpoid alga.Male and female gametophytes differ slightly in their ap-pearance but are basically microscopic uniseriate filaments(sometimes of only a few cells) that grow by apical division.

During sexual reproduction (Figure 3b) darkened sori,the site of unilocular sporangia production, are apparenton the vegetative blade (or sporophylls) of the sporophyte.Meiosis, subsequent rounds of mitosis and finally cytokin-esis generate numerous haploid motile meiospores, whichare released into the water column to find suitable subst-rate. Meiospores germinate as male and female game-tophytes in an approximately 50:50 ratio. Males produceantheridia, each releasing a single motile male gamete,

whereas females develop oogonia, each producing a singleegg that remains attached to the oogonium. Male gametesare attracted to eggs by pheromones and one successfullyfuses with the egg effecting fertilization. The resulting zy-gote undergoes mitotic division to regenerate the sporo-phyte phase, which eventually overgrows the diminutivefemale gametophyte.

Fucales

Fucoids (Figure 1hj) are common components of thecoastal flora and dominate intertidal biomass in many

parts of the world (Figure 1a). In the northern hemispherespecies diversity is low, but in the southern hemispherediversity is rich and the Fucales are considered the ecolog-ical equivalent to the Laminariales of the North. The dip-loid generation, foliose plants constructed of trueparenchyma derived from the action of one or more api-cal cells and their derivative meristoderm, dominates thelife cycle. Unilocular structures are produced in concept-acles, which appear as protuberances on the plant surface,and the conceptacles can be aggregated on swollen por-tions of the plant to produce characteristic receptacles(Figure 1k).

In diplontic life histories the diploid generation is tech-

nically a gametophyte and produces gametes by meiosis(haploid generation is absent), whereas in an alternation ofgenerations the haploid generation is the gametophyte(Figure 3). Fucoid life histories appear diplontic, but thediploid generation is, nonetheless, considered a sporophytebecause life histories are interpreted as a special case ofalternation of generations (pseudodiplontic). Meiosis oc-curs, but free-swimming spores are not released and di-minutive gametophytes develop within the unilocularsporangium. Gametophytes are generally reduced to

gametangia only, although in some species a few vegetative cells are produced (Clayton, 1984). Mature gametophytes are then extruded within a common wall, ansubsequently release gametes into the water columnReproduction is oogamous with motile male gameteattracted to the nonmotile eggs. This interpretation ofucalean gametophyte development within the meio

sporangium is analogous to the condition in land plants.

Palaeontology

Fossils

Fossils are a historical record of the age, nearest relativeand evolutionary progression within and among groups oorganisms. Unfortunately, the predominantly soft tissueof brown algae do not lend themselves to fossilization anauthentic finds are rare. Reports of 0.81.2 billion year-ol

brown algal fossils, and corresponding inferences thathese algae evolved along with many other eukaryotic lineages towards the end of the Precambrian, are not substantiated (Clayton, 1984). Fossils from the Palaeozoiand Mesozoic bear superficial resemblance to extanbrown algae, but are equally comparable to present-daChlorophyta and Rhodophyta. Bona fide brown algal fossils have been reported from 6 to 10 million year-old Miocene deposits (Parker and Dawson, 1965), but are closelaffiliated with extant genera of the Laminariales and Fucales, providing few insights into brown algal evolution anancestry. In the absence of a long and diverse fossil recordtraditional systematists have relied on intuition, compar

ing extant species in efforts to understand phylogenySee also: Algae: phylogeny and evolution; Algal taxonomy: historical overview

DNA alternative

More recently, the tools of molecular biology have provided systematists with new perspectives on brown algaevolution. On the basis of molecular data it has been proposed that the brown algae are a recent group of only 20million years (Saunders and Druehl, 1992), further compromising reports of Precambrian brown algae. Browalgae were considered most closely allied to th

Chrysomeridales, an order of heterokont chromophytesbased on the uncommon lateral insertion of flagella in thesgroups (apical/subapical in other heterokonts). This proposal has received weak support from molecular systematic analyses and until recently, the closest relative to thPhaeophyceae in the molecular trees is the heterokonchromophyte class Xanthophyceae (Saunders etal., 1997The recently described Schizocladophyceae (Kawai et al2003) now resolves as the closest ally to the brown algain molecular trees. Similarly, long-standing views o

Brown Algae


6/7

evolution withinand among brown algal lineages are underincreasing pressure. Consult Druehl et al. (1997) for a mo-lecular perspective on the relationships among extantbrownalgae, and van den Hoek etal. (1995) for an intuitivesynthesis of available data. See also: Molecular phylogenyreconstruction

Ecology

Habitat

Brown algae occur in most coastal environments rangingfrom tropical to polar waters, but display their richest di-versityand greatest biomass in the cold temperate waters ofthe northern and southern hemispheres. The narrow rib-bon of coastline to which most brown algae are confinedaccounts for less than 1% of the earths surface. Never-theless, the most productive areas on the planet are re-portedly brown algal stands (cf. productivity of 0.5 2.5 kg

carbon m22

per year versus 0.42.0 kg carbon m22

per yearfor tropical rainforests; Dawes, 1998). Availability of suit-able substrate generally solid rock is a major factorinfluencing the local abundance and distribution of brownalgae. In addition to epilithic habitat, brown algae grow onother solid substrate, e.g. concrete, wood and metal, asepiphytes on other plants, partially endophytic and somespecies even grow as free-floating populations (e.g. Sar-gassum in the Sargasso Sea). Brown algae can be so abun-dant that they modify, and in fact become, the habitat formany other algae and animals (Figure 1a). See also: Algalecology; Biogeography of marine algae

Brown algae and zonation

Tidal action in the oceans divides the coastal habitat into asubtidal and an intertidal zone. The subtidal zone remainssubmerged even at low tide, and the lower limit of brownalgal growth is dependent on light penetration (abioticfactor) and to a lesser extent on biotic factors (competitionand grazing). In clear tropical waters some browns cangrow to depths of 100 m, whereas in turbid waters fewbrown algae grow below the low water mark.

Tidal cycles expose intertidal seaweeds to atmosphericconditions that can be harsher and more variable than ad-jacent aquatic conditions. Exposure carries the risk of des-

iccation and intertidal algae are well adapted to theirunique environment. For example, many fucoid algae canlose up to 90% of their water and subsequently recovernormal photosynthesis upon rehydration. Organisms thatinhabit the intertidal zone have a restricted vertical distri-bution manifested as distinct bands. In cold temperatewaters brown algae dominate the intertidal zone (Figure 1a)and, therefore, can serve as signature species for the var-ious vertical zones. In the lower Bay of Fundy (NewBrunswick, Canada), for example, representatives of the

Laminariales (Figure 1d) dominate the upper subtidal anlowest intertidal zones. These are replaced by Fucus dstichus ssp. edentatus (Figure 1j ) in the lower intertidal, zone ofAscophyllum nodosum and F. vesiculosus occupiethe mid-intertidal and finally a high intertidal zone dominated by F. spiralis (Figure 1i) is evident. The upper limit oa species vertical distribution is generally controlled b

abiotic factors: tolerance to exposure, temperature andesiccation; whereas, lower limits are established by biotiinteractions, notably competition (Dawes, 1998). In shorstress-tolerant species are confined to higher-stress envronments by relatively more-competitive, less-stress-tolerant species. It should be noted that algal reproductivstages are dispersed to, and probably initiate developmenin,all zones,but algae are only successful where the balancof environmental stress and competition is in their favour

Environment and development

Growth, development and reproduction in brown algae commonly linked to environmental cues including temperature and light (quality, quantity and day length). Kelgametophytes, for example, can overwinter at the singlecell stage, initiating vegetative growth and subsequengametogenesis only when a critical day length is reache(also a minimum quantity of blue light is requiredGametogenesis only occurs, however, when water temperatures are below 158C, thus limiting this response to thspring. Sporophytes of perennial kelp (Laminariales) display a seasonal pattern of vegetative growth and reproduction that is regulated by a combination of day lengtand temperature. The intercalary meristem at the stipe

blade transition zone is active in the spring and initiatedevelopment of a new blade. As it grows, the new bladdisplaces the previous years blade, growth of the formebeing sustained by energy accumulated during photosynthesis in the previous summer and stored in the latter. Thday-length response is a true photoperiodic short-day response similar to the phytochrome response observed foland plants.

Chemical ecology

Algae, in particular Phaeophyceae, accumulate a broaspectrum of secondary metabolites that are generally re

garded as grazing deterrents. Brown algae produce volatilbrominated organocompounds that are released into thatmosphere in amounts equal to the industrial output olike compounds. These compounds contribute to ozondestruction and it has been suggested that holes in thozone over the Arctic in the spring may be linked to enhanced seasonal production of these compounds by browalgae (van den Hoek et al., 1995). These observationdo not serve to mitigate the damage or responsibilitthat humans bear as a result of industrial production o

Brown Algae

6


7/7

ozone-damaging compounds and continued efforts tocontrol use remain essential to the health of the atmos-phere. See also: Algal metabolism; Secondary metabolites:deterring herbivores

A second class of compounds, collectively termedphlorotannins, are stored in the physodes of brown algalcells (Figure 2). Physodes may simply be repositories of

waste metabolites, which also serve an antibiotic role. Spe-cifically, these compounds probably serve to deter herbiv-ores and to inhibit the growth of epiphytic plants andanimals on an algas surface. A role in regulating exposureto sunlight has also been advanced, notably in filtering outharmful ultraviolet radiation, a notion consistent with theabundant occurrence of physodes in surface tissue of in-tertidal fucoids(Clayton, 1984). Therole or roles,however,are yet to be determined with certainty.

Economic Significance

The alginates produced by brown algae are used by thefood and pharmaceutical industries as stabilizing agents inemulsions and suspensions owing to their colloidal prop-erties (Jensen, 1995). New uses are being developed at anever-increasing rate, notably in the biotechnology andmedical fields. Approximately 575 000 tonnes of brown al-gae are harvested per year to provide 21 500 tonnes of al-ginates for the market (van den Hoek et al., 1995). Overhalf of this is from Europe where Ascophyllum (Fucales)and Laminaria (Laminariales) are harvested. Anotherthird is acquired through the mechanical harvesting ofMacrocystis and Nereocystis (Laminariales) from the richkelp forests of the Pacific coast of North America. Kelp arenot only harvested from natural stands, but are cultivatedin many countries both as a source of alginates and forfood. Kelp species of the genera Laminaria and Undaria areparticularly popular food crops in many coastal Asiancountries. Brown algae are also commonly used in agri-culture and horticulture as fertilizers and soil conditioners,and are recognized to have growth promoting qualities.More recently, polyculture the farming of seaweed inproximity to fish cages is being explored as a means ofreducing the impact of aquaculture activities on estuarineecosystems. See also: Fisheries management

ReferencesClayton MN (1984) Evolution of the Phaeophyta with particular ref-

erence to the Fucales. Progress in Phycological Research 3: 1146.

Dawes CJ (1998) Marine Botany, 2nd edn. New York: Wiley.

Draisma SGA, Prudhomme van Reine WF, Stam WT and Olsen JL

(2001) A reassessment of phylogenetic relationships within the

Phaeophyceae based on Rubisco large subunit and ribosomal DNA

sequences. Journal of Phycology 37: 586603.

Druehl LD, Mayes C, Tan IH and Saunders GW (1997) Molecular

and morphological phylogenies of kelp and associated brown algae.

In: Bhattacharya D (ed.) Origins of Algae and their Plastids, pp. 221

235. Vienna, New York: Springer.

Jensen A (1995) Production of alginate. In: Wiessner W, Schnepf E an

Starr RC (eds) Algae, Environment and Human Affairs, pp. 799

Bristol: Biopress.

Kawai H and Sasaki H (2000) Molecular phylogeny of the brown alg

genera Akkesiphycus and Halosiphon (Laminariales), resulting in t

circumscription of the new families Akkesiphycaceae and Halo

iphonaceae. Phycologia 39: 416428.Parker BC and Dawson EY (1965) Non-calcareous marine algae fro

California Miocene deposits. Nova Hedwigia 10: 273295.

Peters AF, van Oppen MJH, Wiencke C, Stam WT and Olsen JL (199

Phylogeny and historical ecology of the Desmarestiaceae (Phaeoph

ceae) support a southern hemisphere origin.Journal of Phycology 3

294309.

Rousseau F, Burrowes R, Peters AF, Kuhlenkamp R and de Reviers

(2001) A comprehensive phylogeny of the Phaeophyceae based o

nrDNA sequences resolves the earliest divergences. Compte Rend

Hebdomadaire des Seances de lAcademie des Sciences, Paris, Scienc

de la Vie 324: 305319.

Rousseau F and de Reviers B (1999) Circumscription of the order Ect

carpales (Phaeophyceae): bibliographical synthesis and molecular e

idence. Cryptogamie Algologie 20: 518.

Sasaki H, Flores-Moya A, Henry EC, Mu ller D and Kawai H (200

Molecular phylogeny of Phyllariaceae, Halosiphonaceae and Tilo

teridales (Phaeophyceae). Phycologia 40: 123134.

Saunders GW and Druehl LD (1992) Nucleotide sequences of the sma

subunit ribosomal RNA genes from selected Laminariales (Phae

phyta): implications for kelp evolution.Journal of Phycology 28: 544

549.

Saunders GW, Potter D and Andersen RA (1997) Phylogenetic affiniti

of the Sarcinochrysidales and Chrysomeridales (Heterokonta) bas

on analyses of molecularand combined data.Journal of Phycology 3

310318.

Schmitz K (1981) Translocation. In: Lobban CS and Wynne MJ (ed

The Biology of Seaweeds, pp. 534558. Berkeley: University of Ca

ifornia Press.

van den Hoek C, Mann DG and Jahns HM (1995) Algae: An Introdu

tion to Phycology. Cambridge: Cambridge University Press.

Yoon HS,Lee JY,Boo SM andBhattacharya D (2001)Phylogeny of t

Alariaceae, Laminariaceae, and Lessoniaceae (Phaeophyceae) bas

on plastid-encoded RuBisCo spacer and nuclear-encoded IT

sequences comparisons. Molecular Phylogeny and Evolution. 2

231243.

Further Reading

Bold HC and Wynne MJ (1985)Introduction to the Algae: Structure an

Reproduction, 2nd edn. Englewood Cliffs, NJ: Prentice-Hall.

Clayton MN (1988) Evolutionand lifehistoriesof brownalgae.Botanic

Marina31

: 379387.De Reviers Band Rousseau F (1999)Towards a newclassification of t

brown algae. Progress in Phycological Research 13: 107201.

Fletcher RL (1987) Seaweeds of the British Isles, Vol. 3: Fucophycea

(Phaeophyceae), part 1. London: British Museum (Natural History

Lobban CS and Harrison PJ (1997) Seaweed Ecology and Physiology

Cambridge: Cambridge University Press.

Lu ning K (1990) Seaweeds. Their Environment, Biogeography, and Eco

physiology. New York: Wiley.

Womersley HBS (1987) The Marine Benthic Flora of Southern Australi

Part II. Adelaide: South Australian Government Printing Division

Brown Algae

Brown+Algae

Documents

Transcript of Brown+Algae