Enteromorpha

Chapter 6 Multicellular Primary Producers: Seaweeds and PlantsSeaweeds-multicellular (a few exceptions), eukaryotes-important source of food, habitat -producers of oxygen for organisms on land and in oceans-economic importance-also called MACROPHYTES or MACROALGAE-NOT PLANTS (Kingdom Protista)-Lack true roots, stems, leavesGeneral Structure:-thallus: complete body-blade: leaflike flattened portion-pneumatocysts: gas-filled bladders-stipe: stem-like structure-holdfast: rootlike portion that attaches thallus to bottom General Structure

Holdfast

3 Major Divisions (Phyla):-Green algae (PHYLUM CHLOROPHYTA)-Brown algae (PHYLUM PHAEOPHYTA)-Red algae (PHYLUM RHODOPHYTA)Green AlgaeCHLOROPHYTAGreen AlgaeMostly freshwater and terrestrial environmentsAlso bays estuaries, rocky tide poolsSimpler thallus than red or brown algaePigments and food reserve (starch) same as land plantsLand plants evolved from green algaeTypically bright green (chlorophyll not masked by other pigments)Genera of Green AlgaeEnteromorphaUlvaValoniaCaulerpaCodiumHalimedaEnteromorphaFilamentousThin thallus in the form of a hollow tubeEnteromorpha

UlvaAlso called sea lettucePaper-thin sheetsShape varies according to environmental factorsPolar to tropicalUlva

ValoniaLarge spheres or clusters of spheresTropical and subtropicalValonia

CaulerpaTropical and subtropicalGreat variety of shapesThin filaments or tubes (siphons) formed by a single giant cell with many nucleiCaulerpa

CodiumDead mans fingersMultinucleated filaments woven into a branching thallusTropical to temperateBoth coasts of North AmericaCodium

HalimedaCalcareous green algaNumerous segments with deposits of CaCO3Accumulation of dead, calcified segments plays an important role in the formation of coral reefsHalimeda

Coral Reef Seaweeds-3 major groupsTurf algae-small, filamentous, colonize vacant surfaces that cover non-living hard surfaces on the reefCoralline algae-red algae; produce hard calcareous skeleton; hold reefs togetherMacroalgae (larger in size)-together with coralline algae plays role in CaCO3 deposition Coral Reef SeaweedsSeaweeds not often regarded as components of healthy coral reefsReefs impacted by pollution are often overrun with seaweedsCoral Reef Ecosystem Divison (CRED) of NOAA found that in central Pacific Ocean (subtropical northwestern Hawaiian islands), some healthy coral reefs are dominated by seaweeds rather than corals Brown AlgaePHAEOPHYTABrown AlgaeVaries from olive green to dark brownContains yellow-brown pigments: FUCOXANTHIN (versus chlorophyll)Usually temperate and rocky polar coastsLargest & most complex seaweeds

Genera of Brown AlgaeEctocarpusDictyotaPadinaDesmarestiaFucusAscophyllumSargassumKelps (several genera: Laminaria, Agarum, Alaria, Postelsia, Egregia, Eisenia, Nereocystis, Pelagophycus, Macrocystis)EctocarpusSimplest brown algaeFinely filamentous thallus

Ectocarpus

DictyotaFlat, branched thallusTropical and subtropical

Dictyota

PadinaLightly calcifiedFan-shapedTropical and subtropicalPadina

DesmarestiaTypically Antarctic, some species in temperate areasDesmarestia

AscophyllumKnotted seaweedTemperate Atlantic coastsAscophyllum

FucusRockweed, wracksAtlantic and Pacific CoastsNorth American and other temperate shoresFucus

SargassumWarm waters, including Gulf of Mexico and CASargasso Sea (in the Atlantic, north of West Indies)Most species grow on rocks2 species float offshore in huge massesSargassum

Sargasso Sea

KelpsLaminariaAgarumAlariaPostelsiaNereocystisPelagophycusMacrocystis

LaminariaSingle large blade, up to 3 m in lengthBlades harvested for foodMay have a split or branched bladeLaminaria

AgarumConspicuous rib runs along the middle of a single bladeAgarum

AlariaLike Agarum, with a conspicuous rib running down the middle of a single bladeBlades can be as long as 25 mAlaria

PostelsiaKnown as sea palm because of its appearanceGrows on intertidal rocks with heavy wave actionThick clusters from central California to British Columbia

Postelsia

NereocystisBull kelpWhip-like stipe up to 30 mLarge, spherical pneumatocyst at upper endNereocystis

PelagophycusSimilar to the bull kelp in sizeAntler-like branchesPelagophycus

Macrocystis***Largest of the kelps***Massive holdfast attached to hard bottomsIndividuals as long as 100 mCan grow 50 cm or more per dayForms kelp beds or forest in the colder waters of the North and South PacificForms some of the richest, most productive marine environments (research kelp communities)Macrocystis

Red AlgaeRHODOPHYTARed AlgaeLargest group of seaweeds (more spp. than green and brown combined)Simple structure, some are completely heterotrophic (parasites)Most appear red; depends on exposure to lightphycobilins: red pigments

Gelidium, GracilariaFound worldwideDense clumps common on upper levels of rocky shores exposed at low tideLonger and flatter branches in areas less exposed to air and in deeper waterGelidium

Gracilaria

EndocladiaWiry clumps on rocky shores from Alaska to Southern CaliforniaEndocladia

GigartinaAmong the most massive red algae with blades as long as 2 m

Gigartina

PorphyraCommon on rocky shores above the lowest tide marks from polar to tropical coastsThallus with thin, large bladesPorphyra

RhodymeniaCommon in the North AtlanticBlades may reach 1 m in lengthRhodymenia

ChondrusIrish mossCommon in the North AtlanticTolerates wide range of temperatures, salinity, and lightShapes vary in response to above factorsChondrus

Coralline AlgaeRed algae that deposit CaCO3 within their cell wallsCalcified thallus takes a variety of shapesColor of live coralline algae is reddish-pinkDead coralline algae is whiteWarm-water coralline algae involved in formation and development of coral reefsSome in temperate and polar waters

Coralline Algae

Life History in SeaweedsIs both asexual (a.k.a. vegetative) and sexual

Asexual: a piece of thallus can grow into a new individual (e.g. Sargassum) Alternation of generations: sexual stage alternates with an asexual onegametophyte alternates with a sporophyte

Types of cell division:Mitosis:resulting cells are identical to originalchromosomes in pairs (diploid or 2n)e.g. somatic cellsMeiosis:resulting cells are haploid (n)gametes contain half the number of parents chromosomes Four types of reproductionType 1 (sea lettuces and kelps)Type 2 (many red algae)Type 3 (rockweeds)Type 4 (some green algae)Reproduction in sea lettuce (Type 1) ***Most common*** Involves 2 types of thalli (sporophyte & gametophyte)Sporophyte generation (2n) goes through meiosis and makes haploid (n) sporesSpores divide and develop into second kind of thallus, a haploid (n) gametophyte generationGametophytes produce haploid gametes which unite to produce a diploid zygoteSometimes separate male and female thalliSometimes male and female gametes produced in one thallusReproduction in sea lettuce (Type 1)

Reproduction in red algae(Type 2)Unique to red algaeSimilar to type 1, but involves a 3rd generation called carposporophyte (2n) from fusion of gametesCarpospores are diploid spores produced by the carposporophyte which develop into sporophytesReproduction in red algae (Type 2)

Reproduction in rockweeds (Type 3) Easiest to understandSimilar to reproduction in animalsNO ALTERNATION OF GENERATIONSOne thallus (2n) Thallus produces haploid gametes by meiosisAfter fertilization, zygote develops into a new diploid thallusReproduction in rockweeds (Type 3)

Reproduction in green algae(Type 4)Dominant thallus is haploid and produces haploid gametesOn fertilization, gametes form a diploid zygoteMeiosis takes place in the zygote, resulting in haploid sporesEach spore develops into a haploid individual and it begins againReproduction in green algae (Type 4)

Economic Importancemariculture: China, Japan, Koreafertilizer, food additives phycocolloids: gelatinous chemicals, used in food processing, suspensions & gelsalgin: stabilizer/emulsifier in diary productscarageenan: from red algae (Irish moss/Chondrus), used as emulsifier (pudding, dairy products)agar: used to form jellies, to protect meats in canning, as thickener, pharmaceuticals, cosmetics

Flowering Plants (angiosperms):Dominant plants on land, few are marineTrue leaves, stems, rootsXylem and phloem to transport water, nutrients, food from photosynthesisGrouped in Kingdom PlantaeReproduction involves a dominant sporophyte with a flower as the reproductive organ

Seagrasses:not true grasses, closest relatives are lilieshorizontal stems (rhizomes) that grow beneath sedimentflowers are small, pollen carried by water currentsseeds dispersed by water currents, in feces of fish and other animals (!)eelgrass (Zostera) is most widely distributed of the 60 known species of seagrass

ZosteraTemperate and tropical regionsShallow, well-protected coastal waters (bays, estuaries)Flat, ribbon-like leavesCommon in oxygen-poor sedimentsZostera beds are highly productive and provide food to variety of animalsZostera

SurfgrassUnusual seagrassInhabits rocky coasts exposed to wave actionMay become exposed at low tidePacific coasts of North AmericaResearch seagrass bedsSurfgrass

Salt-Marsh Plants:Cordgrasses are true members of grass familyNot marine speciesLand plants tolerant of saltDo not tolerate total submergence by seawaterLive in salt-marshes and soft-bottom coastal areasTemperate regionsHabitat and breeding grounds for fishErosion control, natural water purification

Salt-Marsh PlantsLeaves are always partly exposed to airSalt glands in leaves excrete excess saltHalophytes= salt-tolerant plantsPickle weed (Salicornia) is another example

Cordgrass

Pickle weed

Mangroves:Trees and shrubs adapted to live along tropical and subtropical shores around the worldLand plants that can tolerate saltMuddy or sandy shores protected from wavesInclude up to 80 different species of flowering plantsRed MangrovesRed mangroves (tropics and subtropics)extreme northern and southern limits of red mangrove are areas where killing frosts beginSalt marshes replace red mangroves in areas exposed to frost

Red Mangrove

Red MangroveLeaves are thick to reduce water lossSeeds germinate while still attached to parent treeDevelop into seedlings as long as 30 cm before falling from the parentSeedlings stick in muddy sediment or float in the water to new locations