Care for our rocky shores - South African Coastal Information Centre

SEAWEED- A VITAL PART OFOUR ROCKY SHORESAlgae or seaweeds form the bottomof the intricate food chain on rockyshores. These plants are a rich sourceof food for animals like chitons, winkles, limpets, urchins and somecrabs. Also, because the seaweed is broken down into tiny particlesby constant wave action, it provides food for the filter-feeders suchas sponges, barnacles, mussels, oysters, red-bait and tubeworms.All of these are in turn food for bigger species such as starfish,anemones, octopus, fish and birds.Brown seaweed (Dictyota) with red corallinesOver 5 000 seaweed species occur worldwide, with an estimated800 living along our coastline. The South African seaweed kingdomis, in fact, unique in that many of these seaweed species only occuralong our coastline.Seaweeds also provide a unique habitat for many animals to survivein. Here they are protected from the waves, from the heat of thesun, and from possible predators. One tuft of seaweed often supportsa whole community - 1 487 animals comprising different specieswas recorded on a single growth of seaweed!Green seaweed (Codium)Seaweeds occur in a marvellous variety of colours and shapes, bestviewed under water in their natural surroundings. They range fromencrusting coralline algae, which look like paint on the rocks, tolarger leaf-life plants.Seaweeds are generally green, brown or red in colour, dependingon their pigments that absorb light of particular wavelengths.Apart from performing a vital function within their livingenvironment, seaweeds are also harvested for everyday use.Red seaweed (Plocamium)

Extracts from certain seaweeds are used as stabilisers, gellingagents and emulsifiers in thousands of products ranging fromfertilisers, pet food, cosmetics, ice cream and salad dressings totoothpaste and pizza toppings.The jelly found in some seaweed is called agar, a very importantmedium on which bacteria for medical research are cultured.In many eastern countries, seaweed is a sought-after food as it ishighly nutritious and particularly rich in vitamins and trace elements.In South Africa, seaweed is harvested in the Eastern Cape andparts of the Western Cape, and collected as wash-ups on the WestCoast. Although still a young industry, it is already worth R15million annually and has the potential to expand.The Porphyra species, a much sought-after food source in Japan,occurs higher on the shore. It can dry out almost completely atlow tide, only to recover remarkably when the tide comes in.A red seaweed, Gracilaria gracilis is collected in vast quantities atSaldanha Bay, to be exported mainly for the production of agar.Brown seaweed commonly known as kelp (Laminaria)Red seaweed (Porphyra)Harvesting Gracilaria in Saldanha Bay for the production of agar.

STARFISH The starfish family is unique in the animalkingdom as it is the only animal with a body dividedinto five identical arms.SEA URCHINS Feeding on seaweeds in the tidal poolsin which they live, they use their needle-like spinesmainly for defence and their numerous tube-like feetto grab and hold the pieces of seaweed.FEATHER-DUSTER WORM OR GIANT FANWORM Occurring in shady rock crevices, they use theirfans to catch and sort very small food particles.SEA ANEMONES Sporting an array ofcolours, they occur in tidal pools and grabfood particles with their waving tentacles.PEAR LIMPETS (with encrusting coralline algae)Occurring mainly on the south coast, they form densecolonies surrounded by their own characteristic algalgardens on which they feed.FEATHER STARS The delicate armsextending from their circular body are allfringed like feathers to trap small organicfood particles.REDBAIT Brown on the outside, with reddish pink innerflesh, these sea squirts are found all along our coastlineand are commonly collected as bait.LONG-SPINED LIMPETS These have long projectingribs and feed on encrusting brown algae.

OUR IMPACT NEED NOT BE HARMFUL......if we look, but do not touchJust by entering this delicate area, we humans have an impacton the rocky shore environment. However, if we can learn toenjoy the wonders of nature found here simply by observingand not by touching, we can have an extremely fulfillingexperience without doing unnecessary harm.One can imagine how much damage would be done if we wereall to pick up a bit of seaweed, or a seastar, or a sea urchinonly to discard it minutes later on a hot and exposed rocksurface....if we harvest, but harvest the right way.Along the Wild Coast and on the northern shores of KwaZulu-Natal, it is the tradition for coastal communities to collectfilter feeders such as limpets and mussels, which add a richsource of protein to their diet.However, due to increasing numbers of people within thesecommunities, as well as the practice of taking out much morethan is needed and then sorting out the pick of the crop ondry land, these tiny creatures are under severe threat in theseareas.Fortunately, systems of co-management are being introducedwhereby the local community takes on the responsibility ofmanaging their own resources. In this way they not only gainownership, but are also able to sustain this important foodsource.Through educational projects the local community is shownhow easily plant and animal life can be destroyed throughover-harvesting or simply by taking out too many of the youngmembers of a population. Just by using a damaging harvestingtool, such as the commonly used bush-knife, countless littleones are pulled out with each bigger mussel and then left todie.

LET'S ALL PLAY OUR PARTWe can all contribute to the future well-being of our rockyshores and the many unique plants and animals that livehere, by:• Not removing or disturbing any of these plants oranimals unnecessarily when we are in theirenvironment;• Being very aware of the sensitivity of the environmentwhen we walk along the rocks, and by taking care notto step deliberately on any of these creatures;• Enjoying the great beauty of these animals, but nottouching or disturbing them in any way - remembermost of them are stuck to the rocks and cannot moveaway as you approach them;• Not introducing any litter or foreign substances to thisdelicate environment;• Removing any litter you find among these rocks, thatothers have carelessly left behind;• Only harvesting enough to feed yourself and yourfamily, if you are dependent on these creatures as asource of food;• Reporting any destructive and/or illegal behaviour byothers to your nearest conservation authority.

The more aware the public becomes of the importance of conserving ourrocky shores, the better they can be protected. You can help by watchingout for any possible threats to rocky shores in your area, andby keeping in contact with your local conservation authority.For more information, please contact:CoastCARE, The Coastal Management Office, Department ofEnvironmental Affairs and Tourism, Private Bag X2, Roggebaai 8012,Cape Town, South Africa. e-mail: czm@sfri.wcape.gov.zaTel: +27 (0)21 402-3208 Fax: +27 (0)21 418-2582PHOTOGRAPHIC AND ILLUSTRATION ACKNOWLEDGEMENTS: Hein von Horsten, Roger de la Harpe, Claudio Velasquez, MarianneLiebenberg, Rob Anderson, Charles Griffiths, Rob Tarr, and George Branch DESIGN: Runette Louw and Jenny YoungEDITOR: Vanessa Rousseau PROJECT CO-ORDINATORS: Kobie Bredenkamp and André ShareCOASTAL MANAGEMENT OFFICEDepartment ofEnvironmental Affairsand Tourism