Gearing up for the first complete population assessment for the endangered Knysna seahorse in two decades
Article Written by Clement Arendse & Ian Russell
Knysna seahorses, an Endangered estuarine fish, occur only in the Knysna, Keurbooms and Swartvlei estuaries, with the largest and most stable population thought to occur in the Knysna system. In 2022, the Featherbed company in Knysna made a generous donation to SANParks to support research on the Knysna seahorse throughout their range. This funding enabled SANParks to undertake surveys of the distribution and abundance of seahorses in the Knysna Estuary, as a follow-up to population assessments last conducted in the early 2000s.
As a first step, SANParks needed to contract a certified dive supervisor to oversee all diving activities in the project. During the search for an appropriately qualified and experienced dive team, SANParks staff were introduced to the Oceans Alive Conservation Trust, a registered non-profit organisation dedicated to saving and protecting our oceans and coastal environments. Oceans Alive generously agreed to provide the services of a dive supervisor for the project at no cost, along with an additional eight Class IV certified commercial divers to assist with data collection. The volunteer divers were from previously disadvantaged communities, whose training had been sponsored by Oceans Alive, with the Knysna surveys providing valuable work experience in the field of environmental research.
The project started with a few days of diver orientation, with discussions on diving procedures, the Knysna seahorse and its habitat, and data collection methods. This was followed by on-site orientation, to increase diver familiarity with the study sites and the spotting of seahorses.
The generous support from Oceans Alive meant that the dive team was much larger than initially envisaged, allowing more surveys to be undertaken in a shorter time. As a result, SANParks decided to expand the initial phase of the project by including Swartvlei Estuary in the assessment. The diving operation in Knysna and Swartvlei estuaries was initiated in October 2022 and repeated in September 2023. Another assessment is planned for September 2024, which will include the Keurbooms Estuary, thus making this study the first complete population assessment of the Knysna seahorse in two decades. The project will ultimately also include an investigation of the Knysna seahorse habitat in the three systems using an underwater drone purchased with funds donated by the Featherbed Co. This upcoming component of the study is particularly important given the recent proliferation of alien invasive species, and particularly a rapidly spreading red seaweed, within Knysna Estuary, and concerns over the potential negative effects of these newly introduced species on Knysna seahorses.
If you spot SANParks boats on the estuary with divers aboard in September/October 2024, it will likely be the SANParks/Oceans Alive dive group continuing research on our iconic seahorses and their habitat.
The dive team discussing the project and its requirements as part of diver orientation.
The dive team getting ready to enter the Swartvlei Estuary.
Divers undertaking a transect survey as part of the orientation dives.
Knysna seahorse being measured by a diver.
