When Louw Claassens talks about Knysna seahorses, there is a fire in her eyes. Her love affair with this iconic estuarine species (Hippocampus capensis) began after a chance meeting during a field trip with well known local Professor Brian Allanson from the Knysna Basin Project. At the time, she was studying for a Masters degree in Aquatic Health at the University of Johannesburg. The experience so inspired her that after graduating, she moved to Knysna, joined the Knysna Basin Project, shifted her field of study and made researching the status and distribution of the Knysna Estuary's most celebrated aquatic resident her primary mission.
Knysna seahorses are incredibly rare. They have the smallest geographical range of any seahorse and can be found in only three estuaries: Knysna, Swartvlei and Keurbooms. They are unique in that they are the only known true estuarine seahorse species in the world. They are classified by the International Union for the Conservation of Nature (IUCN) as endangered which makes the study and protection of the species critical. The study of seahorses is also extremely valuable because they serve as an indicator species, due to the fact that they are extremely sensitive to the adverse changes in the natural environment. A flourishing Knysna seahorse population could therefore, be indicative of a healthy estuarine system, or vice versa.
Collecting the data is essential. Few people are aware of the importance of the health of the Knysna Estuary. It is the most significant in South Africa in terms of species biodiversity and the protection of fauna and flora in the Knysna Estuary alone would ensure that 42% of South Africa’s estuarine biodiversity is conserved.
Under the banner of the Knysna Basin Project, a non-profit organisation that for nearly twenty years has been involved in monitoring the health of the Knysna Estuary and the impact of human development on this estuarine system, the Knysna Seahorse Status (KySS) project was launched in 2014 and forms part of Claassens PhD study through Rhodes University.
In order to establish the distribution and abundance of the species, researchers need to survey the populations across various habitats and see what, if any, patterns emerge. “Very quickly we found a consistent pattern of considerably higher population densities of the Knysna seahorse within the artificial (gabion) structures of the Thesen Island Marina, as a opposed to their natural habitat, such as eel grass beds” says Claassens.
The project researchers then went on to do 'habitat choice' experiments, where they placed two cages in the marina, one containing the artificial habitat and one containing the natural vegetation. What they found, was that the seahorses almost always preferred the artificial structures when given a choice. There are several theories as to why the Knysna seahorse seeks refuge in the canals of Thesen Island and this all forms part of the study. Much remains unknown.
“The question we have to ask now is “are they thriving here, or are they merely surviving?” Claassens aims to continue her quest once she has completed her PhD this year and if she receives adequate funding she will go on to do her Post Doctorate in order to further study this remarkable species. She hopes that her research can one day also be used for the international conservation of seahorses. Sadly, seahorse populations are threatened in many parts of the world. This is due to habitat destruction, bad fishing practises, and the exploitation for use in traditional medicines.
Claassens believes a lot more needs to be done to manage the species and the estuary as a whole and in order for research and conservation efforts to be successful, public awareness is key and Claassens is passionate about educating the public. The Knysna Estuary needs inspired custodians.
One thing is for certain - Knysna gained a genuine asset the day Louw Claassens decided to make the study of the Knysna seahorse and the estuarine system within which it finds sanctuary, her life's mission!
There have been a great line up of new events at this year's Oyster Festival, but none perhaps quite as inspiring (and environmentally significant) as the Artful Waste Challenge which took place on Wednesday, July 6. On certainly one of the coldest days of the winter, a morning coupled with sporadic rain and icy winds, a total of six teams along with a unit of SANparks rangers, braved the elements to take part in an event that the Knysna Basin Project – the organisers of the event - hope will inspire change. A wave of change!
“The aim of this event, says organiser Louw Claassens, a scientist working for the Knysna Basin Project, “was to raise awareness surrounding the issues of waste in Knysna.” The seriousness of which became exceedingly apparent to all those taking place in a clean-up event earlier in the year., After scouring the southern banks of Thesen Island (a relatively small area of the estuary) at low tide for less than an hour, a total of 16 bags of trash were collected,80% of which, was plastic.
The six teams (which included two visiting teams from Cape Town) then headed to the SANparks tent at the festival grounds where teams had to make something artistic out of the trash collected. All the artworks made sent a clear message about what our trash is doing to our oceans. It is a global problem, but the solution needs to start at a grass- roots, local level, which is the message the Knysna Basin Project is attempting to relay. The Knysna Estuary, our town's most precious aquatic asset, unites with the mighty Indian Ocean in daily tidal dance... often dumping plastic that has made its way into this estuarine system. An estimated 8 million tonnes of plastic end up in our oceans each year – a cause for great concern.
Looking after our lagoon is a collective responsibility. Each and every one of us needs to say NO to single use plastic items and the plastic that we do use must be RECYCLED!!
This event was generously supported by several local businesses: Pick n Pay, Ocean Odyssey Whale Watching and Eco Trips, Knysna Elephant Park and Metelerkamps in association with WESSA Knysna, Sanparks and Knysna Municipality and our Judge, local artist Jan Andre Raats.
For more information: www.knysnabasinproject.co.za
It was a new moon accompanied by a spring low tide the day I joined Knysna Basin Project’s ShoreSearch volunteers on a survey of the Knysna Estuary. The sky was punctuated with clouds and seagulls as we skirted the exposed western bank. In the shallow water nearby, a lone heron stood regal and motionless. Several sacred ibises stood feeding in the thick eel grass beds a little further away. The scene that unfolded before us was beautiful beyond words - one designed by nature to feed the soul.
The wonder of this iconic body of water, however, lies not in its aesthetic character alone, but in the mind-boggling diversity of life which it supports. It boasts such an astonishing web of life that it is rated as environmentally the most important estuary in South Africa.
The Estuary’s gently shelving intertidal shore has an intricate diversity of plant and substratum habitats, all of which provide food and shelter to all sorts of weird and wonderful creatures. Just how many different creatures and the numbers in which they occur is what the dedicated ‘citizen scientists’ of the ShoreSearch project (one of the Knysna Basin Project’s current research programmes).
ShoreSearch kicked off in 2013 with the aim of recording and monitoring the diversity of species found in the Knysna Estuary’s intertidal zone. One of the project’s key objectives is to engage members of the public by encouraging them to participate as volunteers. This opportunity serves as an ideal learning platform for those interested in the natural world.
Led by project leader Frances Smith and her assistant, Peter Smith, we set off on that particularly beautiful morning armed with containers, quadrats, clipboards and curious minds.
Once we reached our survey area, one of 15 different sites chosen throughout the Estuary for this comprehensive study, Frances first released back into the environment all the species she had collected two days earlier for microscopic study.
The surveys are relatively simple and take about 2 hours to complete. The first task is to do a little walkabout noting everything that can be seen in order to build an overall picture of the area. Secondly, a transect line is placed across each habitat zone (e.g., rock, sand, eelgrass) from the low to the high water mark and then everything that is seen on either side is recorded. They then place quarter meter square quadrats in each different habitat zone and count everything found in it, looking both above and just beneath the surface. Some are taken back to the lab to confirm identification (and then released back to their homes).
On this occasion, my eyes were immediately drawn to the sporadic spurts of water coming from holes in the shale beds. I went on to discover that these holes are the life-long home of piddocks, a unique bivalve mollusc which has a set of ridges or ‘teeth’ which are used to grind away at soft rock to create tubular burrows. The piddock – which is rare in South africa - stays in the burrow it bores with only its siphon exposed to take in water that it filters for food.
Another eye-catching creature, of which there were hundreds washed up all along the shoreline, was the shaggy sea hare, an otherworldly looking sea slug quite vivid in colour, which feeds on algae.
It is not immediately obvious to the untrained eye that the shoreline is simply teeming with life, both above the exposed surface and below. Some species are so small that you can easily miss them, or they may be merely lurking just beneath the muddy surface. Guided by the trained eyes of Peter and Frances, the shoreline life is revealed and it is something quite extraordinary to experience the wonders of the world at our feet.
Countless species of fauna and flora were recorded during this survey! These included ribbon worm, isopods, whelks, mud prawn, corrugated venus mollusc, crown crab, false limpets, true limpets, striped barnacle, spiny chiton, cape urchin, plum anemone, polychaete worms, crumb-of-bread sponge, ghost crab, eelgrass, arrow grass, sea lettuce, sea lavender…and the list goes on and on. It was a fascinating and rewarding experience to be a participant in the survey.
After about three years of ShoreSearch surveys, researchers and scientists involved in Knysna Basin Project hope to ascertain just what is living or washed up on the intertidal shores of the Knysna Estuary. How does it compare to previous studies and how has the system changed over the years? This data will help researchers and conservation organisations in their endeavours to protect and maintain the integrity of this celebrated natural asset.