Multicellular Primary Producers

Multicellular Primary ProducersMulticellular AlgaeSeaweeds ( macroalgae)Multicellular algae

Three groups of seaweeds

Red algae phylum(division) RhodophytaBrown algae phylum(division) PhaeophytaGreen algae phylum(division) Chlorophyta

Rhodophyta

Irish Moss - Rich in protein and minerals

CorallinesSecrete a calcium carbonate shell that bond coral colonies together (holds the coral reef structure together)

Nori - Rich in protein and minerals

Phylum Rhodophyta Red AlgaeCorallinesSecrete a calcium carbonate shell that bond coral colonies together (holds the coral reef structure together)Irish MossRich in protein and mineralsNoriRich in protein and minerals

Phylum RhodophytaBiochemistryChlorophylls a, dPhycoerythrin (red pigments)Allow some red algae to live much deeper than any other algaeAs deep as 200 m (656 ft)

Phylum RhodophytaEcological RolesSeasonal food for herbivores, grazersSome form turfs and reef sediments Some stabilize reef sediments

Phylum RhodophytaCommercial usesAgarUsed in medicine and research for culturing microorganismsCarrageenanDesserts, ice cream, milk shakes, sweetened condensed milks, puddings, sauces: gel to increase viscosity thickener : Shampoo and cosmetic creams.

Red Algae Phylum RhodophytaPrimarily marine (98%)The highest diversity among seaweedsMostly benthic in distributionSome species are epiphytes (plant living on plant)Coraline red algae- helps to cement loose coral together

Important commercial uses

Agar culturing bacteriaCarrageenan thickening agentSource of food for human consumption, animal feed, and used in fertilizer

Phylum PhaeophytaBrown AlgaeKelpSargassumRockweed

RockweedPhylum PhaeophytaBiochemistryChlorophylls a, cPigment fucoxanthin

Phylum PhaeophytaEcological RolesLong term food for herbivores, grazersvery productive the Giant Kelp is the foundation for many temperate coastal ecosystems: California, the Mediterranean, and New ZealandKelp form massive undersea forests Habitat for diversity of marine animalsSea urchins, fishes, crustaceans, molluscs, sea lions, sea otters

Phaeophyta

Brown Algae Phylum PhaeophytaRockweeds, kelps, and sargassumAlmost exclusively marine (99.7%)Most are benthic except for SargassumRange in size from microscopic to the giant kelpsOlive-brown color is due to pigment fucoxanthin (also found in diatoms)Brown AlgaeBlades of brown algae usually have gas-filled bladders that help them to stay afloat to get maximum exposure to sunlightThe stipe is attached to the bottom by a holdfast

Ecological roles of SargassumSargassum forms floating mats in the North Atlantic Ocean in an area known as the Sargasso SeaHabitat to a variety of organisms unique to the sargassumMassive mats of sargassum support a complex and diverse communitySeveral species of fish and invertebrates live only in this ecosystem

Phylum PhaeophytaCommercial usesBrown algae is used as a food resourceSeaweeds and algae make up 10% of the Japanese dietThe commercial product algin is used in food processing, salad dressing, ice cream, paint, and abrasivesFood and chemical industries use about $250 million worth of algin annually

Commercial products from Brown AlgaeThe alginates of some brown algae are harvested for commercial use as thickening agents in the textile, dental, cosmetic, and food industriesBrown algae are used as food, and as cattle feedChlorophyta

Phylum ChlorophytaGreen AlgaeSea lettucePhylum ChlorophytaBiochemistryChlorophylls a, bCarotenoidsChlorophyta share the same pigments as land plantsEvolutionarily significant, indicates that land plants evolved from green algaePhylum ChlorophytaEcological RolesSeasonal food for herbivores, grazersManatees eat sea lettuceSome form turfs and reef sedimentsPhylum ChlorophytaCommercial usesCan be used as a compost material and as fertilizerGreen Algae Phylum ChlorophytaContain the same types of pigments that are found in land plants (a,b)Few marine species (13%), most are freshwater and phytoplanktonDistribution of SeaweedsMost species of seaweed are benthicFouling communities live on pilings, bulkheads, boat hulls...The environmental factors most influential in distributionLight and temperature

Structure of SeaweedsThallusThe seaweed bodyBladeFlattened part of the thallusHoldfastAttaches the thallus to a surfaceStipeStem-like region between the holdfast and the bladePhotosynthetic pigmentsChloroplasts in all seaweeds have chlorophyll aGreen algae also has chlorophyll bBrown algae chlorophyll cRed algae chlorophyll d

Composition of cell wallsPrimarily composed of celluloseCalcareous algae may also have calcium carbonateReproduction in SeaweedsBoth asexual and sexualAsexualFragmentationThallus breaks into pieces and each piece grows into a new plantSpore formationSporophyte produces sporesSexualGametes are produced and zygote is formedGametophyte produces gametesAlternation of generationsAsexual sporophyte and sexual gametophyte in same plant