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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
In freshwater biota: limited: Charophytes
•
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 bladelike structures.
1.b. Macroalgae
In freshwater biota: limited: Charophytes
•
•
Along coastlines: rocky substrate + mangroves + salt marshes + seagrasses.
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
In freshwater biota: limited: Charophytes
•
•
•
Along coastlines: rocky substrate + mangroves + salt marshes + seagrasses.
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.
• Underestimated in biodiversity discussions ("invisible").
1.b. Macroalgae
In freshwater biota: limited: Charophytes
•
•
•
•
Along coastlines: rocky substrate + mangroves + salt marshes + seagrasses.
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.
Underestimated in biodiversity discussions ("invisible").
• Requirements for development:
* Salt or brackish water (rare exceptions);
1.b. Macroalgae
In freshwater biota: limited: Charophytes
•
•
•
•
Along coastlines: rocky substrate + mangroves + salt marshes + seagrasses.
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.
Underestimated in biodiversity discussions ("invisible").
• Requirements for development:
* Salt or brackish water (rare exceptions);
* Submerged, at least part of the day;
1.b. Macroalgae
In freshwater biota: limited: Charophytes
•
•
•
•
Along coastlines: rocky substrate + mangroves + salt marshes + seagrasses.
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.
Underestimated in biodiversity discussions ("invisible").
• 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.
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.
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 (+).
• Codium: locally as food.
Chlorophyta: Codium.
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 (+).
Codium: locally as food.
• Halimeda: calcified -> sediments (‘Halimedasand’!! (atolls: up to 90%).
Chlorophyta: Halimeda copiosa
Calcified, segmented thallus
(one segment ~ 0.5 cm).
Chlorophyta: Halimeda tuna (fertile,
with gametangia.
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 (+).
Codium: locally as food.
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)!
Phaeophyta (brown algae)
•
Photosynthetic pigments: chlorophyll a & c + brown pigments
(xanthophylls); cell wall component: alginates !
• Mainly cold water (exceptions).
Phaeophyta (brown algae)
•
•
Photosynthetic pigments: chlorophyll a & c + brown pigments
(xanthophylls); cell wall component: alginates !
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).
Phaeophyta (brown algae)
•
•
•
Photosynthetic pigments: chlorophyll a & c + brown pigments
(xanthophylls); cell wall component: alginates !
Mainly cold water (exc.)
From small and filamentous up to 65 m long; haptera (root-like) + stipe
(stem-like) + lamina (blade-like) + bladders (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).
Phaeophyta (brown algae)
•
•
•
•
Photosynthetic pigments: chlorophyll a & c + brown pigments
(xanthophylls); cell wall component: alginates !
Mainly cold water (exc.)
From small and filamentous up to 65 m long; haptera (root-like) + stipe
(stem-like) + lamina (blade-like) + bladders (floating).
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).
Rhodophyta (red algae)
•
Photosynthetic pigments: chlorophyll a + red and blue pigments; cell
wall component: carrageenans, agar, chalk!
• Mainly warm water (exceptions!).
Rhodophyta (red algae)
•
•
Photosynthetic pigments: chlorophyll a + red and blue pigments; cell
wall component: carrageenans, agar, chalk!
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.
Rhodophyta (red algae)
•
•
•
Photosynthetic pigments: chlorophyll a + red and blue pigments; cell
wall component: carrageenans, agar, chalk!
Mainly warm water (exc.)
From small and filamentous up to 1 m long; mostly composed of
filaments sticking together by jelly.
• 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.
Rhodophyta (red algae)
•
•
•
•
Photosynthetic pigments: chlorophyll a + red and blue pigments; cell wall
component: carrageenans, agar, chalk!
Mainly warm water (exc.)
From small and filamentous up to 1 m long; mostly composed of filaments
sticking together by jelly.
Mostly epilithic, but numerous epiphytic species. Zonation! Mainly subtidal
+ intertidal pools (desiccation).
• 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
Caulerpa racemosa sold as vegetable in Thailand
Rhodophyta (red algae)
•
•
•
•
•
Photosynthetic pigments: chlorophyll a + red and blue pigments; cell
wall component: carrageenans, agar, chalk!
Mainly warm water (exc.)
From small and filamentous up to 1 m long; mostly composed of
filaments sticking together by jelly.
Mostly epilithic, but numerous epiphytic species. Zonation! Mainly
subtidal + intertidal pools (desiccation).
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.
Rhodophyta: mariculture of Eucheuma in Indonesia: collecting the
fully grown specimens in boats.
Rhodophyta: mariculture of Eucheuma in Indonesia: drying in the
sun.
Rhodophyta (red algae)
•
•
•
•
•
•
Photosynthetic pigments: chlorophyll a + red and blue pigments; cell
wall component: carrageenans, agar, chalk!
Mainly warm water (exc.)
From small and filamentous up to 1 m long; mostly composed of
filaments sticking together by jelly.
Mostly epilithic, but numerous epiphytic species. Zonation! Mainly
subtidal + intertidal pools (desiccation).
Porphyra (nori): most important sea-vegetable!! Mariculture.
Fundamental research (reproduction) --> applied research
Eucheuma (a.o.) --> carragheenophytes!! Mariculture.
• Gelidium: --> agar. Mariculture.
Rhodophyta: Gelidium pulchellum (agarophyte, Brittany).
Rhodophyta (red algae)
•
•
•
•
•
•
•
Photosynthetic pigments: chlorophyll a + red and blue pigments; cell
wall component: carrageenans, agar, chalk!
Mainly warm water (exc.)
From small and filamentous up to 1 m long; mostly composed of
filaments sticking together by jelly.
Mostly epilithic, but numerous epiphytic species. Zonation! Mainly
subtidal + intertidal pools (desiccation).
Porphyra (nori): most important sea-vegetable!! Mariculture.
Fundamental research (reproduction) --> applied research
Eucheuma (a.o.) --> carragheenophytes!! Mariculture.
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).
Rhodophyta (red algae)
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).
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.
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.
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:
- 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 records
update of floristic knowledge
48 species new to Kenya and Tanzania
Example
Dictyota adnata Zanardini
type locality: Irian Jaya (Indonesia)
 New: East Africa
Coppejans (1990)
Research Group Phycology, Ghent University
Research along the East African coast
Gibsmithia hawaiiensis
type locality: Hawaii
known from Australië
new: East Africa, South Africa
Seychelles
subtidal
De Clerck et al., Bot. Mar. (subm.)
Research Group Phycology, Ghent University
Research along the East African coast
New species
Vanvoorstia incipiens
intertidal
1 location: Uroa, Zanzibar
De Clerck, Wynnne & Coppejans, Phycologia (1999)
Research Group Phycology, Ghent University
Ecological roles of the seaweed vegetations
• Defining intertidal and subtidal habitats (incl. fauna!)
Ecological roles of the seaweed vegetations
•
Defining intertidal and subtidal habitats (incl. fauna!)
• Large biomass, even in mangroves and
seagrass vegetations -> important role!
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)
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.
• Pollution, eutrophication: 'greening of the
coast': Ulva (incl. Enteromorpha).