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www.thevillagenews.co.za
29 January 2020
MY ENVIRONMENT
The Village NEWS is proud of its partnership with Daily Maverick which allows us to republish articles from their website, dailymaverick.co.za, that are of interest to Overberg residents.
If you go down to the beach today… you’re in for a big surprise By Dr Anina Lee
With over 1.5 million unique users a month on its website, Daily Maverick is the foremost purveyor of South African news. Go online to thevillagenews.co.za and search the titles in bold below to read a few of their popular articles.
E
veryone who lives in or visits Hermanus knows Grotto Beach. It is famous for its sparkling blue water (albeit a tad chilly), an unspoilt golden beach stretching all the way to Gansbaai, and the occasional whale spy-hopping, lob-tailing, and even breaching just off-shore. If you take a stroll along the tide line, you will still find a few shells – but not so many these days. The beach is perhaps a bit too pristine. Where are the multitudes of interesting sea shells, the hermit crabs and the little plovers? Even the kelp is moved off the blue flag swimming beach.
What should you do if you’re depressed but can’t afford therapy? You might be surprised to know that the leading cause of disability worldwide isn’t a communicable disease, heart disease or back pain: it’s depression. Depression is extremely common, in both rich countries and poor countries.
But have you ever looked to see what lurks under the sand? A wide open sandy beach like Grotto is a dangerous place if you are a small animal. Gulls, mongooses, crabs and other predators have their beady eyes on you. Hot, drying sun, harsh winds, changing tides and pounding waves are your enemies. So hide, little fellow, hide. What creatures hide in the sand and what do they eat? A feature of our coastline is the kelp forests that form a habitat for many marine creatures. Kelp is a primary producer in this ecosystem. It contains chlorophyll and therefore can use the sun’s energy to photosynthesise and produce sugars and other nutrients for aquatic life, including abalone. During high seas, kelp is washed up on our pristine beaches, where it rots in the sun.
Making South African extra virgin olive oil, from grove to factory floor Most of South Africa’s olive groves are owned by just 11 growers, who each have more than 50 hectares of trees. TGIFood goes behind the scenes to see how this luxurious liquid is made on a large scale.
SA Youth to Cyril Ramaphosa: South Africa is out of touch with Climate Crisis reality As we write this, South Africa is in the grip of a devastating drought. Farmers are committing suicide; more than 30,000 farming jobs have been lost. Towns across South Africa are running out of water. Food security is threatened, leaving our people less resilient.
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However, the stink of rotting stranded kelp is a temporary problem. It is soon solved by a myriad of little creatures that are hidden in the sand above the high water mark. Beach hoppers (Talorchestia capensis) are commonly termed ‘beach fleas’. They are actually air-breathing marine crustaceans with modified gills and are related to shrimps. They are not only champion jumpers but have prodigious appetites. Adults daily consume 60% and juveniles 100% of their body weight. They annually rid the beach of up to 1.8 tons dry weight per metre of sand or 53% of rotting kelp! For protection against desiccation and predatory birds, beach hoppers live in burrows on the high shore during daylight hours. When the moon rises to provide them with the necessary coordinates for navigation, they scramble down the beach as a task force of up to 25 000 per square metre. After attacking the kelp all night for its sugars, they set new coordinates by the rising sun and return to base. They have a builtin navigation system synchronised to the position of the sun and the moon over their beach. If they are moved to a beach with a different orientation they will scramble the wrong way. Sand lice (Tylos capensis), also called ‘pill bugs’, are also good at cleaning up seaweed debris on beaches. Like the beach hoppers their lives are controlled by the tides and the dark of night. ‘Sand lice’ emerge from their burrows only after dark and only at low tide. They progressively delay their nightly appearance by 50 minutes each day, to coincide with low tidal periods. When these low tides begin to occur after dawn, the sand lice reset their biological clocks to emerge
at the next low tide after dusk. Amazingly, sand lice continue this rhythm even in laboratories when there are no environmental influences. My firm favourites of the sandy beach live in the intertidal zone – the part of the beach that is sometimes under water and sometimes dry. It is a very challenging place to live and find food. Plough snails (Bullia sp.) also have rhythms of activity. Plough snails move up and down with the tide, using their large ‘foot’ as a sail with the waves. They stop exactly where the waves drop the food they carry – and the snails detect it by smell and swarm all over it. Their favourite food is dead jellyfish and bluebottles. Their sense of smell or ‘chemodetection’ is their superpower. They attack the food using a proboscis (trunk) to slurp up the food. Hand-feeding Bullia snails is surprisingly exciting. We are all familiar with the shells of white or sand mussels (Donax sp.) that wash up on the beach. In order to feed, sand mussels extend two siphons above the sand to find food in the water that washes over them. One siphon, with a frilled edge to keep out sand grains, draws in food-laden water and then passes it through the gills where the food is filtered out. The filtered water is expelled through the second siphon. It may seem hard to believe, but these mussels, especially young ones, also move up and down the beach with the tide. They come out of the sand and the waves of the rising tide roll them half-way up the beach, where they once more dig in. When the tide starts to go out, they hitch a ride with a wave down the beach and wait for the next tide. Our challenge is to find some mussels and watch them filter-feeding. Digging will be required. So, if you go down to Grotto Beach with Whale Coast Conservation on Tuesday 4 February at 17:30 you’re in for a big surprise. Booking is essential as numbers are limited. Tickets are R120 for adults and R60 for children. Mail anina.wcc@gmail.com to secure a place. Children are especially welcome.
ABOVE: Beach hoppers (Talorchestia capensis), commonly known as ‘beach fleas’ and Sand lice (Tylos capensis) are good at cleaning up seaweed debris on beaches. PHOTO: iSpot Nature BELOW: Donax sand mussels move up and down the beach with the tide to feed. PHOTO: WCC BOTTOM: The favourite food of plough snails such as this Bullia digitalis is dead jellyfish and bluebottles. PHOTO: commons.wikimedia.org
