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Knysna Seahorse Status

KySS - Knysna Seahorse Status - update

It is the end of an era for the Knysna Seahorse Status project! Louw Claassens submitted her thesis which was accepted in August 2017. She attended the Rhodes University graduation ceremony in March 2018.

Our initial research found that Thesen Islands Marina, and specifically the Reno mattresses, provide suitable additional habitat to the Knysna seahorse. More specifically, we found that seahorse densities within the marina are almost twice that found in eel grass beds within the estuary. After an in situ choice experiment, we found that seahorses were much more likely to remain on or move towards an artificial Reno mattress structure, compared to natural eel grass.

We also investigated the behaviour of the Knysna seahorse on the Reno mattress habitat by deploying GoPro cameras. Firstly, we found that this technique works well for studying seahorse behaviour! We also noted that Knysna seahorses perform a morning courting dance (similar to other seahorse species), and that they spend about 80% of their time feeding (not surprising seeing that these animals do not have a fully developed stomach and need to feed continuously). A more concerning observation was a major decrease in feeding and a complete halt in courting behaviour during the busy holiday season. One possible cause for this is the high noise levels created by boats during this time.

For more info on our behaviour work, and to see some of our video footage, please have a look at a guest blog Louw Claassens wrote for Crittersresearch:

To read more about our research outcomes, please refer to the scientific journal articles published as part of our research:

Claassens, L., Hodgson. 2018. Monthly population density and structure patterns of an endangered seahorse Hippocampus capensis: a comparison between natural and artificial habitats. Journal of Fish Biology. IN PRESS. https://www.ncbi.nlm.nih.gov/pubmed/29675915

Claassens, L., Booth, A.J., Hodgson, A.N. 2018. An endangered seahorse selectively chooses an artificial structure. Environmental Biology of Fishes. 101(5): 723-733. https://link.springer.com/article/10.1007/s10641-018-0732-4

Claassens, L., Hodgson, A.N., 2017. Gaining insights into in situ behaviour of an endangered seahorse using action cameras. Journal of Zoology. DOI: 10.1111/jzo.12509. http://onlinelibrary.wiley.com/doi/10.1111/jzo.12509/abstract

Claassens, L., 2016. An artificial water body provides habitat for an endangered estuarine seahorse species. Estuarine, Coastal and Shelf Science. 180. 1-10. http://dx.doi.org/10.1016/j.ecss.2016.06.011

Our work has been presented at two international conferences (Syngbio in Tampa in 2017 and ECSA57 in Perth in 2018), as well as at two local conferences (ZSSA in 2016 and SAMSS in 2017) and it is safe to say that our Knysna seahorse is known worldwide.

We are continuing our seahorse research and the next phase will entail an investigation of the home-range, site fidelity, population size and growth rate of seahorses within Thesen Islands Marina. We will do this by using a mark-recapture approach and marking the seahorses with a tiny VIFE tag (http://www.nmt.us/products/vie/vie.shtml). To find out more about the next phase of our research have a look at the September issue of the SANCOR newsletter: https://sancor.nrf.ac.za/Documents/SANCOR%20Newsletter%20222.pdf

We urge all to continue looking after the most iconic resident in this marina! Keep in mind that this tiny seahorse is listed as endangered on the IUCN Red List and is specifically threatened owing to its small population size, limited range and habitat vulnerability. Even though Thesen Islands Marina has provided additional and suitable habitat to this animal, it is everyone’s responsibility to continue advocating for the protection of our Knysna seahorse. All estuary users can help, by taking it slow (no wake), limiting boat noise (no need to rev that engine!), being mindful of the tidal nature of our estuary (spring low tide is no time for boating) and by keeping a protective eye on our seahorses!

During the past few years our research has been featured on various television shows, from 50/50 to Carte Blanch and even by Beautiful News (https://www.beautifulnews.co.za/stories/louw-claassens). We look forward to continuing our work on this beautiful animal and hope to achieve great conservation success going forward. We would also like to thank Thesen Islands Homeowners Association and all home owners that made this research possible!

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