Algae & Seaweed. To familiarize the marine guide with the most common seaweeds of Southern Africa

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1 WildlifeCampus - Marine Field Guiding 1 Module # 7 Component # 1 Algae & Seaweed Objective To familiarize the marine guide with the most common seaweeds of Southern Africa Expected Outcomes: The learner will be able to: Describe the basic structure and function of seaweeds Describe the reproductive processes of seaweeds Recall the basic types of seaweeds Discuss the economical and ecological importance of seaweeds Pre-test: Test your current knowledge of marine guiding. Question 1. Seaweeds have roots like the terrestrial plants Yes No

2 WildlifeCampus - Marine Field Guiding 2 Introduction Many explorers are unsure about what kind of organism s seaweeds and algae really are. They are in fact one and the same thing although, whereas all seaweeds are algae, all algae are not seaweeds. Seaweeds are roughly placed in three groups namely the green, brown and red algae. In appearance they are similar to plants with roots, branches and even leaves but they are in fact quite different because the roots are not roots at all but rather anchoring devices or holdfasts. Even the leaves or fronds do not anatomically or physiologically resemble leaves as we know them although their main function is also photosynthesis. However, there are also microscopic or planktonic algae of interest especially in the form of dinoflagellates (some of which may cause red tide) Then there are zooxanthellae (algal forms imbedded in other creatures e.g. corals) and Diatoms (one of the most abundant marine organisms). Another form of algae is encrusting algae, called encrusting corallines, which are laden with lime, making them hard and deterrent to grazers. They look like encrusting coral or course lichen. One thing that algae and seaweeds generally have in common is the fact that they create useful sugars using carbon dioxide, water and some essential elements by trapping and utilising sunlight energy in simple organelles called chloroplasts. This process is called photosynthesis and one of its by-products is oxygen. Over millions of years our earth s atmosphere was pumped full of this waste product by the ever increasing and diversifying plants and algae. This very process is therefore responsible for the air we breathe and we must know that was it not for the photosynthesising plants and algae, earth would not have been inhabited by the likes of us.

3 WildlifeCampus - Marine Field Guiding 3 But is it a Plant? Some say yes, sort of and some say no, not really. So far they have been placed in their own group or kingdom called Protoctista. This kingdom includes weirdo microscopic single celled creatures and multi celled larger seaweeds. The protoctista have in common: Cells with at least one nucleus Nucleus with a double membrane In the nucleus there are at least two different chromosomes Cells divide by mitoses They evolved from symbiosis between two or more different bacteria Not all Protoctista photosynthesise! However, those mentioned here as algae and seaweeds do in fact photosynthesise. Furthermore the value of seaweeds as economic factor have grown significantly over the last fifty years to a point that we now use it in the manufacture and production of: Jelly Soup ice cream instant puddings cheese sausage casing cereals icing and even stabilizer for beer foam. These days it is also utilised as food, food supplements, source of gels and fertilizer. This module will focus on the green, brown and red algae, commonly known as seaweeds.

4 WildlifeCampus - Marine Field Guiding 4 Function & Structure The three types of algae differ functionally due to the difference in the fractions of sunlight that they absorb. Normal sunlight (or white light) contain all the colours that we know and the reason why something appears as a colour is that the object reflects that particular colour while the rest of the colours are absorbed by the object. Therefore green algae appear green because it reflects light at the wavelength that we perceive as green. Sea water also absorb fractions of light to the extent that between 50 and 150 meters of depth the light is reduced to less than 1% of its value at the surface. This is also why seaweeds occur in relatively shallow waters. The first colour to be filtered out is red and violet light and the light that penetrates the deepest in water is blue-green light hence the blue colour of deep waters. A further structural difference between various types of algae depends on their environment and position on the shore. Mid-shore wave beaten algae are normally flexible, thin and elongate so that they can withstand lashings. Upper shore algae sometimes tend to be more succulent and broad so that they can withstand drying conditions in the sun and so that they can maximize their photosynthesis during the relatively short periods under water. Algae in deeper calmer waters are more likely to be wide and large in order to increase poor light uptake in deeper waters. In protected deep rock pools and low-shore pools one is likely to find delicate and semi-rigid types. Brown algae : Phaeophyta (Kelps wracks and sargassums) This type of algae is generally khaki brown to bottle brown in colour and they represent the largest of the seaweeds. Some kelps forests along the west coast may reach a height of up to 12 meters. The reason for the brownish colour is the presence of the two types of pigments chlorophyll A and C (green) and fucoxantin (brown). Because kelps are in deeper waters they can absorb the blue-green light energy effectively and pass it to the green pigments (whom, on account of being green actually reflects the blue-green light and can t use it). So the brown fucoxantin absorbs the blue-green light and passes the energy onwards to the chlorophyll, which uses it in photosynthesis. A unique starch called laminarin is produced in brown algae.

5 WildlifeCampus - Marine Field Guiding 5 Green Algae: Chlorophyta (Bright green algae) The green algae are arguably the forebears of green land plants since they also contain chlorophyll A and B. Green seaweeds are particularly simple in structure and have only three basic body plans. Some form thin sheets with only one to two cells thickness. Others from hairy filaments (hair-weeds) with single cells placed end to end. A third, more complex type, the Siphonales, are made up of a network of fine branching tubes with numerous nuclei and only few cross walls. The absence of cross walls is functional since the chloroplast can move around in the tubes to make the most out of available light. Red Algae : Rhodophyta There are numerous species of red algae found on the fringe of the South African coast. They range from large flat, blood red sheets to delicately branched to succulent, red brown forms. They contain in addition to chlorophyll A also the unique red and blue pigments called phycocyanin and phycoerythrin. The red and blue pigments benefit the red algae in that they can absorb the blue-green light that penetrates the deeper waters and pass its energy on to chlorophyll A for use in photosynthesis. Therefore red algae can live both high on the shore (shallow waters where red light is absorbed by chlorophyll A) or in very deep waters (where the blue green light is absorbed). Deep water red algae have more red pigments while intertidal red algae have less red pigments with the result that they appear reddish brown, yellowish or almost black. This may cause confusion with some of the brown algae and one red algae species can even be confused with green algae since it appears to be bright green (However the base of the seaweed is pinkish and a dead giveaway to its red algae heritage). Red algae are also relatively palatable and a major staple food source for many marine herbivores like mollusks, crustaceans and fish. They are also more likely to flourish in the nutrient rich west and south coasts than on the east coast. Their structure vary according to their environments. Those high up on the shore are usually large and flat in order to maximize photosynthesis during the short period they spend under water and they have the ability to withstand drying out (desiccation) due to a gel (agar) that they contain in their tissues Very much like a marine succulent. Mid shore species need to content with periods of desiccation as well as severe wave lashings and therefore they are mostly branched with papillae on the fronds, which increases the surface area for photosynthesis without causing too much resistance in the wave action. Deep-water species are once again large

6 WildlifeCampus - Marine Field Guiding 6 and flat as well as red to make use of the deeper penetrating blue-green light. Some red algae grow epiphytically on other algae, especially kelps.

7 WildlifeCampus - Marine Field Guiding 7 Reproduction Most algae have two or more life cycles in much the same way that an insect can have a larval stage (caterpillar), pupa stage as well as a sexual stage (e.g. butterfly). The life cycles of the chlorophyta (green algae) is the simplest with alternating phases of either sporophyte or gametophyte generations. The sporophytes produce spores, which are released and then disperse to settle and develop into male and female sexual gametophytes. The gametophytes release male or female gametes (eggs and spermatozoids), which fuse (sexually) to form a zygote that develops into a new sporophyte. The two generations are similar in appearance meaning that if the sporophyte phase of the cycle looks like a thin flat frond then the gametophyte looks similar. The life cycles of the phaeophyta (brown algae) is slightly different and in many species a giant or large (Dominant) sporophyte alternates with a microscopic gametophyte, i.e. the giant west coast kelps are the sporophyte phase that produces spores and the spores develop into microscopic female and male gametophytes within which the sexual gametes (eggs and spermatozoids) are formed. The life cycles of the rhodophyta (red algae) is the most complex, mostly up to three generations in one cycle. In this instance it may start with a tetrasporophyte (It s spores are produced in groups of four), which releases tetraspores. The tetraspores develop into sexual gametophytes, which may or may not resemble the tetrasporophyte. The female gametophytes produce eggs (gametes), which are not released but retained within. The male gametes therefore fertilize the eggs within the female gametophyte. Upon fertilization the egg becomes encased in a wart-like cyst and develops into a carposporophyte. The carposporophyte in turn will develop carpospores that are released so that they can settle and grow into new tetrasporophytes.

8 WildlifeCampus - Marine Field Guiding 8 Phylum: Phaeophyta (Brown Algae) Kelps Kelps mostly have a root-like anchor, a stem (called a stipe) and leaf-like fronds. Most of the kelps have growth points situated in the middle of the plant or where fronds joint the stipe (stem). The significance of this is that the fronds can tear and weather away at the tips but it will continue lengthening through growth further down. The fronds are many cells thick with: Protective outer layer Pigmented photosynthetic cells Storage tissues containing starch and tannin (deters herbivores) Sporangia (producing spores) on raised patches (also called Sori) The stipes also have specialized tissues with: Strengthening tissues Tubular cells (to transport food through the kelp) Sea bamboo (Ecklonia maxima) West coast Small sea bamboo (Ecklonia biruncinata) South coast Spined kelp (Ecklonia radiata) Cape point and south coast Split fan kelp (Laminaria pallida) West coast Bladder kelp (Macrocystis angustifolia) West coast Bushy seaweeds with stems and blade-like fronds (some of which have bladders to make them boyant and hold them up to the light. Special reproductive branches can be found in the axils of the fronds. Can be found in deep gullies and intertidal pools. Not all sargassums are coastal, the famous Sargasso Sea (called the windless doldrums by bored sailors trapped in it) is a free-floating (pelagic) sargassum weed-dominated ecosystem in the western North Atlantic. It is situated in a ever circulating combination of the Gulf Stream and other currents. Sargassum stays afloat by producing gas-filled bladders, which act like buoys and many organisms find their habitat in it. In fact this environment is so specialised that certain organisms (fish, sea-horses, nudibranchs, etc.) take on the appearance of the sargassum weed in order to prevent predation. Southern African sargassums:

9 WildlifeCampus - Marine Field Guiding 9 Different leafed sargassum (Sargassum heterophylum) West to east coast Long leafed sargassum (Anthophycus longifolius) Cape point to east coast Ornamented turban weed (Turbinaria ornata) East coast Acid weed Long yellowish fronds with severely serrated edges. This algae contain sulphuric acid to deter herbivores. It occurs sub-tidally below kelp beds. Acid weed (Desmarestia firma) West coast Wracks Wracks occur on wave-pounded rocks in hanging carpets. They have tough cylindrical stems that hang from an anchoring holdfast with branching blades further down. The spear-shaped blades are dotted with regular cavities on the margins that produce gametes. Hanging wrack (Bifurcaria brassicaeformis) Lower west coast Upright Wrack (Bifurcariopsis capensis) Lower west coast Cushions and bladders The Oyster thief (Colpomenia sinuosa) Occurs from cape point to the east coast and it grows epiphytically on other algae in low tide pools. Since they are cushion-like and hollow they can become a nuisance in oyster farms because they attach to the oysters and then lift them and drift away into the sunset. Brown brains (leathesia difformis) is a similar species. The dead-man s fingers (Splachnidium rugosum) have swollen yellow to brown finger-like bladders. They are sometimes exposed during low tide and may then appear withered due to loss of water, hence the name. Spores are released from pores in the skin. Simple Brown Algae Dictyota group - Flat forking dichotomous branches Spotted dictyota (Dictyota naevosa) South and east coast

10 WildlifeCampus - Marine Field Guiding 10 Smooth tongued dictiopteris (Dictyopteris ligulata) South to east coast Fans Flat branches with fanned tips Multi fanned zonaria (Zonaria harveyana) Cape point to south coast Articulated zonaria (Zonaria subarticularia) Cape point to east coast Turkey tail (Padina boryana) Phylum: Chlorophyta (Green Algae) Flat sheets (Order: Ulotricales) Sea lettuce (Ulva spp.) and Green sea intestines (Enteromorpha intestinales) resort under this group and can be found in intertidal pools and estuaries along the Southern African coast. They can tolerate varying salinities from river water or rain diluting the sea or estuary as well as higher salinities caused by rapid evaporation. They release spores from the edges of the fronds especially in the rising tide when sea water flows into the rock pools. Spores quickly colonise new or bare patches where they settle after being dispersed by the waves. Sea lettuce is edible to humans. Filaments or hair seaweed (Order: Cladophorales) Grows in hairlike or grasslike tufts along the side of pools or attached to other larger seaweeds. It appears hairy because the single cells are positioned end to end in long filaments. The hairs flow with the wave action and this prevents breakage. Spores are released from the tips of filaments. Robust hair-weed (Chaetomorpha sp.) Unbranched West coast to east coast Branched Cladophora (Cladophora sp.) Branched - West coast to east coast. Complex green seaweeds (Order: Siphonales) Mostly with fine branching tubes and numerous nuclei with few or no cross-walls. The nuclei can therefore move around in the extended cells and either retreat from too much light exposure or move towards the light e.g. when parts of the plant is submerged below sand. Many contain chemicals that act as deterrent for herbivores. Sea moss (Bryopsis flanaganii) Moss-like, East coast Berry caulerpa (Caulerpa racemosa) Green berry-like bunches, East coast

11 WildlifeCampus - Marine Field Guiding 11 Feathery caulerpa (Caulerpa holmesiana) Stiff feathery, Cape point to lower East coast Strap caulerpa (Caulerpa filiformis) Upright straps in sandy gullys, Cape point to east coast Wedge weed (Halimeda cuneata) Wedges stuck together giving the impression of mini-cactus weed, South coast to east coast Sea brush (Chamaedoris delphinii) Resembles green paint brushes, Lower to upper east coast. Green fans (Udotea orientalis) Stalked tough flat fan, Upper east coast. Codiums (Codium spp.) Cylindrical or flattened thick spongy branches, Cape point to east coast. Green balloons (Valonia macrophysa) Glistening interlocked dark-green balloon-like sacs, East coast.

12 WildlifeCampus - Marine Field Guiding 12 Phylum: Rhodophyta (Red Algae) High shore, intertidal flat red seaweeds Purple laver (Porphyra capensis) is a membranous seaweed that reminds of crumpled black plastic bags when exposed during low tide. Female plants have pink edged sheets and the males have yellow edges from which the gametes are released. Porphyra is edible to humans and can be found from the west coast to the lower east coast. Slippery orbits (Aeodes orbitosa) yellowish brown tough sheets attached to rocks in the mid shore region by a flattened disk. Hedgehog seaweed (Notogenia spp.) is dark brown and occurs on sheltered rocks from the west coast to the lower east coast. The gametophyte phase is covered with small branched outgrowths, hence the name. Mid-shore, intertidal red seaweeds Earthworm champia (Champia lumbricalis) flourishes on the wave beaten rocks of the west coast. They appear like earthworms with dividing segments and they contain fertile branches that produces the gametes. Another Champia (Champia compressa) is more flattened or compressed and found on the south to east coast. Twisted Gigartina (Gigartina striata) has fleshy blades that are small and branched to prevent being torn apart by the waves. Tongue weed (Gigartina radula) is flat and tongue shaped, found in deeper waters and is redder and covered with papillae. Typical Tongue weed Jelly weeds (Gelidium spp.) are tough, wiry and dark red, found below the littoral zone or even on the shells of limpets in order to evade being grazed upon. They Plocamiums (Plocamium spp.) are handsome feathery types, usually pinkish, with groups of curved branches.

13 WildlifeCampus - Marine Field Guiding 13 Fork branched Flat galaxaura (Galaxaura diessingiana) Deep pink, Flat forked fronds with light banding and impregnated with lime. Cape Agulhas to east coast. Comb-fan weed (Trematocarpus flabellatus) Comb-like fans with flat yellow to purple-brown fronds. West coast and south coast. Forked gigartina (Gigartina scutellata) Succulent twig-like branches that forks at short intervals. Tips are swollen with a pronounced indent. West coast. Wine weed (Epymenia spp.) broad to narrow flat reddish pink to wine red blades. West coast to east coast. Upright coralline algae (Jointed or articulated segments) Finely forked corallines (Jania spp.) Slender jointed symmetrical forked branches found around South African coasts. Arrowhead corraline (cheilosporum sp.) Segments arrow shaped, East coast. Hinged corallines (Arthrocardia spp.) Stout wedges, oval in section with up to four branches at a joint.

14 WildlifeCampus - Marine Field Guiding 14 Ecological and Economical Importance It should not be forgotten that seaweeds play an integral part in the ecology of inshore waters for not only are they a source of food but they also create a range of habitats for sea creatures and other algae. They also buffer the effects of wave action and they provide shelter. Purple laver (Porphyra capensis), called Nori in Japan, is the most valuable seaweed product because it is high in protein and contains a complete range of trace elements and high levels of iodine. The iodine is used in the treatment of goitre and thyroid problems. Red algae yield agar-agar (dissolves when warm but forms a gel when cool) Used in pharmaceutical work and in bacteriological research. Agar weed (Gracilaria verrucosa) was once used, harvested from Saldanha bay but the weed beds were virtually destroyed, Gelidium was also used on the Transkei coast. Brown algae (especially the kelp Ecklonia maxima) yields alginic acid which is also used in a gel form but it forms salts with a wide range of metals such as sodium, calcium, copper and iron which has varying solubilities that can be altered with changing conditions. The can therefore be used in insoluble form to bind materials together but at any stage their solubility can be changed and the alginate removed. This is useful to waterproof cement, to seal fine papers, to stabilize toothpaste, paint, ink and explosives plus many other products. Alginic acid also fixes radioactive strontium meaning that if you work at a US nuclear station, daily doses of this alginate will allow the strontium to pass out of the body. Ecklonia maxima also increases butter fat content of cow milk by 15 percent and relieves eczema in dogs. As fertilizers kelp have proven useful as a growth stimulant due to the inherent hormones like gibberellins, auxins and cytokinins. It also assists in germination of many crop plants (e.g. 2 litres per ha as an additive to normal fertilizer may increase yield from 20 to 300 percent). Care must be taken to sustainably harvest (or grow it through clever Mari culture ploys) kelp resources since it is limited in SA and plays an integral role in the ecology of the ocean.

15 WildlifeCampus - Marine Field Guiding 15 Bibliography This component leaned heavily on information gleaned from: Coastcare, Fact Sheet Series, 2001, Marine and Coastal Management, Department of Environmental Affairs and Tourism. Branch, G. M. & Branch M.L The living shores of Southern Africa. Struik, Cape Town. Branch, G. M., Griffiths, C.L., Branch M.L. & Beckley, L.E Two oceans: A guide to the marine life of Southern Africa, David Philip, Claremeont, Cape Town.