J20 macroalgae

Question 1

evolutionary history

Answer 1

-Cyanobacteria 3.5 billon year old prokaryote precursors of chloroplast
-Red algae are the oldest plant-based fossils, found in remains of stromatolites (cyanobacteria mats) dating 1.6 billion years, 400 million years older than any other plant fossils
-The oldest eukaryote fossil (1.05 bill years) strongly resembles the modern red algal genus Bangia
-Chlorophyta thought to have evolved around 1 billion years ago, are ancestors of land plants
-Ochrophyta evolved 150-200 million years ago. The heterokonts are thought to have incorporated red algae in their cells which became their chloroplasts (bound by 4 membranes).

Question 2

Macroalgae

Answer 2

12,000 species
-Ocean basins, distribution b temperature, light, salinity, nutrient, pH, wave exposure, grazing, human impacts, etc…
-635 seaweed species in UK (350 red), macroalgae biodiversity
-Primary producers, ecological/economic importance, habitat builders, commercial uses. Seaweed farms are mostly in Asia, only six main types of seaweed are farmed worldwide.
-If it has officinalis in the name it probably has a human health benefit
-There is a growing need for seaweed, in jobs/livestock/health products.

Question 3

Seaweed

Answer 3

Blades/frond (leaves), stipe, holdfast (roots), spores, no conductive tissue. Other organisms live in the fronds and holdfasts or algae. Gastal bladders are in some, to help them stand up in the water column.

Question 4

Seagrass

Answer 4

Leaves, stalk, roots/rhizomes, seeds of fruits, xylem/phloem like tissues

Question 5

Functional group, texture, example genera

Answer 5

Functional Group Texture Example Genera
Sheet Soft Ulva, Porphyra
Filamentous Soft Ectocarpus, Polysiphonia, Chaetomorpha
Coarsely branched. Fleshy, wiry Gracilaria, Ahnfeltia
Thick, leathery Rubber Fucus, Chondrus, Laminaria.
Jointed calcareous Hard Corallina
Crustose Hard Lithothamnion

Question 6

Pigments of algae

Answer 6

• Green seaweed/also land plants = Chl a, Chl b, carotenoids, cellulose
• Brown algae swap Chl b for c = Chl a, Chl c, fucozanthin, caretoenoids, alginates
• Red algae swap Chl c for d = Chl a, Chl d, caretenoids, Phycobilins (phycoerythrin, phycocyanin)

Question 7

Reproductive modes

Answer 7

-Vegetative = fragmentation, propagules (small algae juice buds that drift off)
-Asexual = non-motile spores, zoospores
-Sexual = gamete fusion

Question 8

Life history

Answer 8

• Gametic life history = gamete is the only haploid cell produced, like humans
• Zygotic life history = zygote is the only diploid cell produced
• Sporic life history = alternating between multicelled 2n and 1n generations. A sporophyte is multicelled 2n plant that makes 1n spores by meiosis.

Question 9

Green algae: Chlorphyta

Answer 9

1700 species
-Storage product is starch, sometimes in pyrenoids
-Contain cellulose and sometimes pectin and hemi-cellulose in their cell walls

Ulva spp. have a Sporic life history, the diploid and haploid phases are isomorphic (look the same).

Question 10

Brown algae: Phaeophycaea

Answer 10

2000 species
-Kingdom Chromista, not a true plant
-Storage product is laminarin
-Contains cellulose and alginic acid in cell walls
Colpomenia peregrina (oyster thief), invasive species, kind of looks like a sack, often attach to oysters and carry them away.

Laminaria spp. Has a sporic life history and the diploid/haploid phases are heteromorphic (look different).

Question 11

Zonation of Fucoids

Answer 11

-Lower shore = Fucus serratus
-Middle shore = Ascophyllum nodosum, Fucus vesiculosus
-Upper shore = Fucus spiralis, Pevetia canaliculata

Question 12

Kelp forest

Answer 12

Tallest species is 65m, huge biodiversity, fix carbon (we don’t know where the carbon actually goes).
Wash up a lot during winter, broken down by arthropods.

-Laminara hyperborea, Saccharina latissima (high sugar content, like shelter), Laminaria digitata (flexible stipe), Alaria esculenta (colder water, exposed conditions).

Question 13

Gametic life history

Answer 13

The gamete is the only haploid cell produced
-Laminaria spp. Have a Sporic life history and the diploid and haploid phases are heteromorphic (look different).

Question 14

Red algae: Rhodophyta

Answer 14

7000 species
-Storage product is Floridian starch
-Contain cellulose, agar, and carrageenan in their cell walls
-Heteromorphic alterations of generations

Prophyra sp. Is used to make Nori in Japan sushi, Kathlees Drew-Baker found out how they reproduce, named mother of the sea now.
-Has a heteromorphic alteration of generations

Question 15

Calcareous algae

Answer 15

In all three macroalgal groups
-Precipitate calcium carbonate withing, between and on their tissue
-In the form of calcite or aragonite, different forms = crusts, branched, nodular, epiphytic. Can be green, red, or brown.

Question 16

Maerl beds

Answer 16

Important in the ocean carbonate budget
-High biodiversity and sensitive habitats
-They have a mixture of sediment types that they like, but only grow around 1mm per year.

Question 17

Invasive seaweeds

Answer 17

Non-native, often arrive through human activities, recent developments. Can be released by ships or aquarium, or mostly aquaculture industries (in every step of the transport system there could be many species on oyster shells etc.