Knysna Estuary ShoreSearch Update

We have now completed at least 3 full assessments using transects and quadrats with the help of our volunteers on our 12 sites around the estuary, including a number on the western shore. So we have a mass of data to collate and analyse and I have spent a busy time during the long, hot English summer (we are ‘swallows’) pulling this together and I am aiming to start producing reports in the new year. (more…)

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Wondering how pollution affects the estuary?

Knysna Estuary pollution

Plastic bottles, coffee cups and plastic packets, just some of the litter scooped up by the fantastic team working for SANParks, collecting litter before it gets into the Knysna Estuary. These aren’t the only pollutants that flow down our rivers and streams and reach the sea life in the estuary. Oils, grease and heavy metals like zinc and lead can be washed off roads or flushed into rivers by irresponsible industrial users. Nitrogen and Phosphorous rich water can originate from sewage spills from burst pipes or residents and farmers using too much fertiliser on gardens and crops. Think before you wash anything into the stormwater drains because chances are this will end up in the rivers and finally the estuary!...

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Have you seen the horses under the sea?

Knysna Seahorse Project

Sometimes, we don’t realise the curiosities that could be found right at our doorstep, all you must do is look. If you ever find yourself around the Thesen Island Marina in Knysna, be sure to look out for a little boat chugging along with a couple of students and a pool net on board. They’re not there to scoop leaves out of the Marina, I’m afraid, but rather to look for an illusive little fish known as the Knysna seahorse (Hippocampus capensis). (more…)

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Keurbooms Seahorse Research Project

Keurbooms Seahorse Research Project

My past twenty years of research work at sea involved taking along bins of equipment -glassware, chemicals, oceanographic instruments, batteries and spares for everything. So, walking down to the Keurbooms Estuary for this month’s seahorse survey with all my sampling gear inside a small rucksack, feels minimalistic to say the least. The 50m Research vessel has now been replaced by a canoe, and with my family as crew we set off on an ebbing tide to search for Knysna seahorses, albeit in the Keurbooms Estuary. This is one of the few localities other than Knysna, that this endangered species calls home. (more…)

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What lies beneath

What lies beneath by Johan Wasserman

Beneath the surface of the Knysna Estuary lies a rich diversity of plant and animal life which, until now, has been largely unexplored. Due to recent developments in Remote Operated Underwater Vehicle (ROV) technology, we can now discover what lies beneath our estuary. Using an ROV and Geographic Information System (GIS) software, we plan on creating a map that depicts the subtidal habitats of the Knysna Estuary. Estuarine habitats act as nursery areas for many important fish and invertebrate species, providing them with food and shelter for at least a part of their life cycle. As such, the subtidal habitats of estuaries often host diverse communities. It is important to study the distribution of these habitats for conserving and managing...

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What effect has the blanket of Ulva had on the animals of Leisure Island’s Steenbok Channel shoreline?

What effect has the blanket of Ulva had on the animals of Leisure Island's Steenbok Channel shoreline?

In early 2011, when the Steenbok Channel was clothed in a luxuriant and healthy eelgrass bed, Richard Barnes investigated its invertebrate fauna at a series of nine points (at Kingfisher Creek near its junction with the Ashmead Channel, at its head near the Armstrong Causeway, and at a point halfway between the two, adjacent to the Reserve's Indigenous Garden; and at three points down the shore at each of those three sites - low water neap, mean low water, and low water spring).  Early this year, he sampled those same nine points again but in 2018 in areas of bare mud left after loss of the seagrass.  This was a race against time before the bare mud itself disappeared under...

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Progress on identification of the Moonshine baitworm in Knysna Estuary

Progress on identification of the Moonshine baitworm in Knysna Estuary

The Moonshine worm, a popular bait worm that can be found almost anywhere in the Knysna Estuary, now most likely seems to be an alien species. Our work started owing to a rise in popularity in use of the Moonshine worm as bait among local fishermen. Further investigation showed that these worms were not found within the Knysna Estuary during the 1950’s and 90’s, during extensive ecological surveys. This provides strong circumstantial evidence that these worms moved into the Knysna Estuary some time during the last two decades. The question that arose was whether the worms moved in from another local area, such as a nearby estuary or the ocean floor, or whether it was brought here from elsewhere. (more…)

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Water quality monitoring in the Knysna estuary

KEMP Knysna Basin Project

The winter of 2017 was somewhat drawn out, cold and occasionally wet which fortunately did not interfere with the necessary sampling of the estuary water column in the vicinity of Thesen Jetty.  At this site KEMP, a part of the overall Knysna Basin Project had set up a Hach Ott multiparameter sonde well below the surface at low water and delivered real time changes in dissolved oxygen acidity (pH), water levels, and measured chla fluorometrically (digitally). (more…)

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Sea Star Sundays

The Spiny sea star Marthasterias glacialis

The Spiny sea star Marthasterias glacialis is widely distributed. However, the South African Marthasterias population has been reclassified as Marthasterias africana. These critters were easy to spot with their vibrant orange and purple colourings and their arms covered in small spines. The spread of M. africana within The Knysna Estuary is suspected to be because of the invasive mussel species Mytilus galloprovincialis, as it is the sea star’s main source of food. (more…)

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