1.b. macroalgae in freshwater biota: charophytes limited to oligotrophic, alkaline waters

1.b. Macroalgae

In freshwater biota: Charophytes limited to oligotrophic, alkaline waters.

Charophyta: left: dense vegetation;Right: detail.

1.b. Macroalgae

In freshwater biota: limited: Charophytes

• Along coastlines: on rocky substrate + in mangroves + in salt marshes + on seagrasses.

Rocky shore with extensive macroalgal (seaweed) vegetations.

Mangrove with aerial roots (pneumatophores) densely covered by epiphytic

algae, mainly red algae (Rhodophyta).

Seaweed growth in a young salt marsh vegetation (Salicornia europaea).

Macroalgae in seagrass vegetations: the brown alga Dictyota epiphytic on Thalassodendron ciliatum.

1.b. Macroalgae


• Along coastlines: rocky substrate + mangroves + salt marshes + seagrasses.

• Plant body = thallus: NO vascular bundles (no "true" roots, stems nor leaves although they can look like -); NO flowers; NO seeds (spores!).

Chlorophyta: Caulerpa sertularioides: structures SIMILAR to higher plants: stolonoïds, rhizoïds and feathery assimilators.

Phaeophyta: Laminaria: structures SIMILAR to higher plants: haptera, stipe and blade.

Rhodophyta: Zellera tawallina with holdfast, stem-like and

blade-like structures.

1.b. Macroalgae



• Plant body = thallus: NO vascular bundles (no "true" roots, stems nor leaves); NO flowers; NO seeds (spores!).

• Photosynthesis and uptake of nutrients by whole thallus.

1.b. Macroalgae





• Underestimated in biodiversity discussions ("invisible").

1.b. Macroalgae






• Requirements for development:

* Salt or brackish water (rare exceptions);

1.b. Macroalgae






• Requirements for development:* Salt or brackish water (rare exceptions);

* Submerged, at least part of the day;

1.b. Macroalgae






• Requirements for development:* Salt or brackish water (rare exceptions);

* Submerged, at least part of the day;

* Hard substrate: lithophytes (few exceptions: special anchorage).

1.b. Macroalgae

Species diversity: approximate numbers• Red (Rhodophyta = ± 4000-6000 spp), green

(Chlorophyta (macroalgae only!) = ± 2000 spp (+ microalgae = ~ 15000) and brown (Phaeophyta = ± 900-1500 spp) algae [and blue-greens: see micro-algae].

1.b. Macroalgae

Species diversity: approximate numbers• Red (Rhodophyta = ± 4000-6000 spp), green (Chlorophyta (macroalgae

only!) = ± 2000 spp (+ microalgae = ~ 15000) and brown (Phaeophyta = ± 900-1500 spp) algae [and blue-greens: see micro-algae].

• Some area's more species rich than others: Pacific: Philippines, Japan; Atlantic: Europe!! (N-Spain, France, UK); Caribbean!! Red Sea & Indian Ocean?? South Africa!! (different climate zones).

1.b. Macroalgae

Species diversity: approximate numbers• Red (Rhodophyta = ± 4000-6000 spp), green (Chlorophyta (macroalgae

only!) = ± 2000 spp (+ microalgae = ~ 15000) and brown (Phaeophyta = ± 900-1500 spp) algae [and blue-greens: see micro-algae].

• Some area's more species rich than others: Pacific: Philippines, Japan; Atlantic: Europe!! (N-Spain, France, UK); Caribbean!! Red Sea & Indian Ocean?? South Africa!! (different climate zones)

• Most species rich: not tropics >< terrestrial plants.

Chlorophyta (green algae)

• More closely related to higher plants than to the brown or red algae!!: photosynthesis by chlorophyll a & b, storage product = starch, cell wall component: cellulose.



• Ulva (incl. Enteromorpha): bioindicators of eutrophication (+ importance of correct ID!!)

Chlorophyta: Ulva lactuca, Sea lettuce (Wimereux): 2-

layered membrane, ~ 20 cm large.

Chlorophyta: Ulva (Enteromorpha) intestinalis, Intestine weed (Wimereux): 30 cm long.

Chlorophyta: massive development of Ulva in the intertidal (Wimereux) as a result of eutrophication of the coastal

water.

Chlorophyta: Cladophora (Rockweed): habit and detail. Some species growing in freshwater.

Chlorophyta: Bryopsis spp.



• Ulva (incl Enteromorpha): bioindicators of eutrophication (+).

• Codium: locally as food.

Chlorophyta: Codium.





• Halimeda: calcified -> sediments (‘Halimeda-sand’!! (atolls: up to 90%).

Chlorophyta: Halimeda copiosa

Calcified, segmented thallus (one segment ~ 0.5 cm).

Chlorophyta: Halimeda tuna (fertile, with gametangia.





• Halimeda: calcified -> sediments!! (atolls: up to 90%)

• Caulerpa: food/toxic; C. taxifolia & C. racemosa-problem in the Mediterranean Sea.

Chlorophyta: Caulerpa racemosa var. racemosa: spherical assimilators.

Chlorophyta: Caulerpa opposita typespecimen of a new species but locally extremely abundant.

Phaeophyta (brown algae)

• Photosynthetic pigments: chlorophyll a & c + brown pigments (xanthophylls); cell wall component: alginates (see Human uses)!


• Photosynthetic pigments: chlorophyll a & c + brown pigments (xanthophylls); cell wall component: alginates !

• Mainly cold water (exceptions).



• Mainly cold water (exc.)

• From small and filamentous up to 65 m long; haptera (root-like) + stipe (stem-like) + lamina (blade-like) + bladders (floating).

Phaeophyta: Pylaiella littoralis: habit: branched filamentous (Wimereux): detail of a portion ~ 5 cm long.

Phaeophyta: Laminaria saccharina, large specimen in Brittany (Roscoff): ERASMUS field-course.

Phaeophyta: Laminaria saccharina: haptera, stipes,

meristematic zone (arrows), basis of the blade (Wimereux).

Phaeophyta: Laminaria saccharina: blades with double row of undulations.

Phaeophyta: Fucus vesiculosus, Bladder weed (Wimereux) with air vesicles (floating).





• Zonation! Adaptation to dessication, salinity and temperature fluctuations + competition.

Phaeophyta: Pelvetia canaliculata-vegetation in the upper intertidal (Wimereux).

Phaeophyta: Fucus spiralis with numerous receptacles (swollen reproductive structures) in the high intertidal.

Phaeophyta: Fucus vesiculosus, in the middle intertidal (Wimereux).

Phaeophyta: Ascophyllum nodosum: replacing Fucus vesiculosus on sheltered places (Wimereux).

Phaeophyta: Fucus serratus, low intertidal (Wimereux).

Phaeophyta: Himanthalea elongata: zone between intertidal and subtidal (Brittany).

Phaeophyta: Laminaria-zone at spring low tide: Wimereux (L. saccharina, L. digitata).





• Zonation! Adaptation to dessication, salinity and temperature fluctuations + competition.

• Dictyota & Padina frequent in tropics; also Sargassum ID-problems!! + drifting spp.

Phaeophyta: Dictyota dichotoma.

Phaeophyta: Padina pavonica in situ (Mediterranean Sea).

Phaeophyta: Sargassum muticum (Japweed) in situ in a low intertidal rock pool.

Phaeophyta: Sargassum muticum (Japweed): detail with air bladders and receptacles (Wimereux).

Rhodophyta (red algae)

• Photosynthetic pigments: chlorophyll a + red and blue pigments; cell wall component: carrageenans, agar, chalk (see Human Uses).


• Photosynthetic pigments: chlorophyll a + red and blue pigments; cell wall component: carrageenans, agar, chalk!

• Mainly warm water (exceptions!).



• Mainly warm water (exceptions!).

• From small and filamentous up to 1 m long; mostly composed of filaments sticking together by jelly.

Rhodophyta: Acrochaetium: top left: tufts of small filaments (~1 cm); other illustrations: microscopic details with spore formation.

Rhodophyta: Palmaria palmata, a tough, relatively large (~ 20 cm), blade-like red alga (Wimereux, subtidal fringe).

Rhodophyta: Batrachospermum: detail of the anatomy: filaments sticking together by jelly: central axis and

whorls of branchlets.



• Mainly warm water (exc.)


• Mostly epilithic, but numerous epiphytic species. Zonation! Mainly subtidal + intertidal pools (desiccation).

Rhodophyta: Palmaria palmata (red arrows), in situ, epilithic and the brown algae Laminaria digitata ( brown

arrow) and L. saccharina (yellow arrow) (Wimereux).

Rhodophyta: Polysiphonia lanosa, epiphytic (hemi-parasitic) on Ascophyllum nodosum (brown alga) (Wimereux): detail.

Collecting red algae in an intertidal rock pool (uplift).

Subtidal fringe close to Digue Nord (Boulogne): zone dominated by red algae.






• Porphyra (nori): most important sea-vegetable!! Mariculture. Fundamental research (reproduction) --> applied research.

Rhodophyta: Porphyra purpurea: habit: membranous blade of ~ 30 cm long (Wimereux).

The story of Nori and Kathleen Drew– Traditional: Porphyra growing on Bamboo (Hibi).

• The story of Nori and Kathleen Drew– discovery of the life cycle: Conchocelis-phase by K. Drew

• triphasic, anisomorphic cycle

• tetraspores (conchospores) grow in oyster shells

• Nori: now a modern industry.

Caulerpa racemosa sold as vegetable in Thailand






• Porphyra (nori): most important sea-vegetable!! Mariculture. Fundamental research (reproduction) --> applied research.

• Eucheuma (a.o.) --> carragheenophytes!! Mariculture.

Rhodophyta: Eucheuma sp. (Tanzania): carragheenophyte.

Rhodophyta: mariculture of Eucheuma in Indonesia: attaching branches on the ropes; in the background: bags of dried

specimens.

Rhodophyta: mariculture of Eucheuma in Indonesia:

bamboo floaters with ropes.

Rhodophyta: mariculture of Eucheuma in Indonesia: ropes with young attached specimens.

Rhodophyta: mariculture of Eucheuma in Indonesia: underwater image (seagrasses on the seabottom).

Rhodophyta: mariculture of Eucheuma in Indonesia: fully grown specimens ready for collecting.


collecting the fully grown specimens in boats.


drying in the sun.






• Porphyra (nori): most important sea-vegetable!! Mariculture. Fundamental research (reproduction) --> applied research


• Gelidium: --> agar. Mariculture.

Rhodophyta: Gelidium pulchellum (agarophyte, Brittany).






• Porphyra (nori): most important sea-vegetable!! Mariculture. Fundamental research (reproduction) --> applied research


• Gelidium: --> agar. Mariculture.

• Corallines: "cement in coral reefs"; Med. Sea: calcified platform; coralligène; maërl (industry --> destroyed).

Dead coral skeletons, completely overgrown by Corallinaceae (calcified red algae).

The seaward, surf-exposed margin of the reef, cemented by Corallinaceae,

resulting in a pinkish colour.

The seaward, surf-exposed margin of the reef, cemented by Corallinaceae.

Rhodophyta: Corallinales. Encrusting representative:

Phymatolithon lenormandii on rock (Brittany).

Rhodophyta: Corallinales. Pseudolithophyllum expansum (with epiphytic Halimeda): forming extensive structures

at great depth (>50 m), the “coralligène” (Mediterranean Sea).

Rhodophyta: Corallinales: Lithophyllum tortuosum: forming a ridge (“le trottoir”) at high tide sea level, especially at surf-

exposed sites (Mediterranean Sea).

Rhodophyta: Corallinales: Lithophyllum

tortuosum-"trottoir" (Mediterranean Sea).

Rhodophyta: Corallinales. Segmented representatives: left: Corallina officinalis, right: Cheilosporum sagittatum

(Australia).


Some other representatives from the N-French coast (Wimereux).

Rhodophyta: Gracilaria gracilis: (Wimereux), a carragheenophyte.

Rhodophyta: Chondrus crispus (Irish moss): (Wimereux): carragheenophyte.

Rhodophyta : Plocamium cartilagineum (Wimereux).

Succession; zonation; niche diversity

• Bare surface -> Bacteria -> filamentous algae -> 'fleshy' seaweeds (-> seagrasses).


• Bare surface -> Bacteria -> filamentous algae -> 'fleshy' seaweeds (-> seagrasses).

• Conspicuous zonation (species according climate).

- Intertidal: exposure to air conditions towards high tide: desiccation, temperature & salinity variations!

- Subtidal: wave action & light (quality and quantity); down to depth with enough light for photosynthesis.

Dike at Pointe de la Crèche, Boulogne (N France): Verrucaria maura (blackish lichen), Blidingia minima (light green), Porphyra umbilicalis (brownish purple), Ulva compressa (dark green), Fucus spiralis (blackish brown), on the bottom: many Ulva.

Zonation in the Mediterranean Sea: intertidal with Rissoella verruculosa,

Lithophyllum tortuosum, Cystoseira mediterranea.

Succession; zonation; niche diversity Bare surface -> Bacteria -> filamentous algae -> 'fleshy' seaweeds (->

seagrasses).

• Conspicuous zonation (species according climate).

• Intertidal: exposure to air conditions towards high tide: desiccation, temperature & salinity variations!

• Subtidal: wave action & light (quality and quantity); down to depth with enough light for photosynthesis

• Geographic distribution: 5 marine phytogeographical zones (upper and lower boreal, temperate, subtropical and tropical) defined by critical temperatures:

- min temperature for survival;

- min temperature for repopulation;

- max temperature for repopulation;

- max temperature for survival.


• Bare surface -> Bacteria -> filamentous algae -> 'fleshy' seaweeds (-> seagrasses).• Conspicuous zonation (species according climate).• Intertidal: exposure to air conditions towards high tide: desiccation, temperature

& salinity variations!• Subtidal: wave action & light (quality and quantity); down to depth with enough

light for photosynthesis• Geographic distribution: 5 marine phytogeographical zones:

- min temperature for survival;

- min temperature for repopulation;

- max temperature for repopulation;

- max temperature for survival.

• Cosmopolitan species (??!! >< molecular data -> numerous sibling species). Patchiness!! Disjunct distribution.

Research along the East African coast

New recordsupdate of floristic knowledge48 species new to Kenya and Tanzania

ExampleDictyota adnata Zanardinitype locality: Irian Jaya (Indonesia) New: East Africa

Coppejans (1990)

Research Group Phycology, Ghent University


Gibsmithia hawaiiensistype locality: Hawaiiknown from Australiënew: East Africa, South Africa

Seychellessubtidal

De Clerck et al., Bot. Mar. (subm.)


New speciesVanvoorstia incipiens

intertidal

1 location: Uroa, Zanzibar

De Clerck, Wynnne & Coppejans, Phycologia (1999)



Ecological roles of the seaweed vegetations

• Defining intertidal and subtidal habitats (incl. fauna!)



• Large biomass, even in mangroves and seagrass vegetations -> important role!




• Consumption, phycocolloids.

Algal uses and economical potential• Uses

– food

– fertilisers

– phycocolloids

– fine biochemicals

– (fermentation and pyrolysis)

Algal uses and economical potential• Human food

– 600 BC• “Some algae are a delicacy fit for the most

honoured guests, even for the King himself”

• 21 species are used in Japan, 10% of the daily diet

– Nori = Porphyra

– Kombu = Laminaria

– Wakame = Undaria

Algal uses and economical potential• Human food

– Europe and America– health food

– traditional foods

» laver bread (Porphyra)

» cheese (Dulse: Palmaria palmatifida)

– dying agents for textiles

– pharmaceuticals (since pre-christian times: ~ officinalis)




• Consumption, phycocolloids.

• Pollution, eutrophication: 'greening of the coast': Ulva (incl. Enteromorpha).

1.b. macroalgae in freshwater biota: charophytes limited to oligotrophic, alkaline waters

Documents

day slide

freshwater biota

true roots

vascular bundles

plant body

seeds spores

uptake of nutrients

rocky shore