Finding the Knysna Seahorse: Mini-blog 6

August 21, 2018August 21, 2018 / Maarten De Brauwer / Leave a comment

I feel like I only just arrived in South Africa to look for endangered seahorses, but instead I am flying to Johannesburg where I will catch a connecting flight to Perth. This trip was no different than other fieldwork trips in that regard: what looks like a long time of sampling at the planning stage just flies by before you know it.

Louw and me have been busy since the last mini-blog. Most importantly, we successfully finished sampling! The last locations were less explored areas than the first ones, which is very exciting. Even if we do not find seahorses in these spots, they give inspiration to come back for new research projects.

Cormorant in Jongensfontein

After wrapping up the sampling we visited Stellenbosch University. The university is the home to the von der Heyden Lab, which specialises on genetic research for conservation and biodiversity planning. They also have an eDNA project which investigates fish diversity in South Africa. During our visit I gave a talk about my own research to the marine students in the university. It was great to share my love for strange critters, especially since the students had some very relevant questions at the end of the talk. As much as I enjoy talking (or writing) about my research, it’s even more fun to have a conversation about it and getting a fresh look through someone else’s eyes.

South African penguins (Spheniscus demersus) taking a stroll

In the last two days of the trip we relaxed, caught up with friends, and explored Cape Town and False Bay. The highlights were definitely diving in the kelp forests of Simonstown and visiting the nearby African penguin (Spheniscus demersus) colony. While I have dived in cold water before, I never had the pleasure of seeing this particular ecosystem. If you ever have the opportunity, I can highly recommend it!

Kelp diving

If a coral reef dive is like swimming through an underwater flower garden, kelp diving would be the equivalent of walking through a forest. There’s something very special about weaving your way through underwater plants that reach from he bottom all the way to the surface. The sunlight is filtered and the canopy above creates shadows you just do not get in other kinds of diving. On top of that, the bottom is very rich with all kinds of life. There are plenty of invertebrates like sea urchins, featherstars and nudibranchs. The fish life is very different than what I am used to, the small pufadder shysharks (Haploblepharus edwardsii) only live in South Africa area and are the cutest little things. To top it off, two southern right whales passe by close to shore as we were exiting the water. Louw even managed to snorkel out and catch a glimpse of them!

I guess it’s safe to say that this trip has been a successful one. It will be another few months before we will have all the results, but I am very excited to discover in which places we found the elusive Knysna seahorse!

Not a bad spot for a dive…

Finding the Knysna Seahorse: Mini-blog 5

August 13, 2018 / Maarten De Brauwer / 1 Comment

It’s already been a week since I arrived in South Africa to study the endangered Knysna seahorse with Dr. Louw Claassens from the Knysna Basin Project. Together we are testing if environmental DNA (eDNA) can be used to find rare seahorses and pipefishes.

38875489_206756850187960_5584208399702163456_n

eDNA filtering in progress

To do this, we have been travelling along the southern coast of South Africa, taking water samples along the way in estuaries where our focal species lives, where it used to live, or where it might live. Yesterday we left Knysna to sample water in Klein Brak and Groot Brak. We are especially interested in the Klein Brak estuary, since there are multiple anecdotes that the Knysna seahorse (Hippocampus capensis) used to live here. Nobody has checked recently if it really was the Knysna seahorses and it seems that the most recent sighting has been many years ago. Because of this, it is usually assumed that there are no more Knysna seahorses in Klein Brak.

This brings me to a very important (maybe the most important?) question about this whole endeavour: WHY are we actually doing this? It’s all good an well to say that we want to help these endangered animals, but what exactly are we hoping to achieve? What will our results mean for managing the endangered Knysna seahorse, the critically endangered Estuarine pipefish, or any other endangered small fish for that matter?

Knysna estuary, just imagine all the seahorses down there!

What we are hoping to achieve can be summarised in three main points.

We want to test if the eDNA method can really be used to find small, endangered fishes (particularly seahorses and their relatives). So far, previous research has shown that eDNA work on large fishes such as sawfish, but it is not sure yet if this will work for seahorses, which are obviously much smaller.
The best case scenario would be that we could also find seahorses in estuaries where it was thought to have disappeared. This would be great news for the conservation status for the species, as it would mean that it occurs in a wider area than we thought, which would mean that it is less likely to go extinct.
If this would happen, it would mean two things. First of all, the new locations would have to be studied, so we can find out how many live in these estuaries. It would also mean that those new places need extra protection and monitoring to ensure the species do not disappear from their newly discovered homes.

Ultimately, if the eDNA method works for small, endangered seahorses (or their relatives), it could be used to monitor small fishes worldwide. This would help solving one of the biggest problems with studying small species, especially those that are rare or hard to find.

Louw looking for Knysna seahorses in the Thesen Island Marina (she found 3!)

Finding the Knysna Seahorse: Mini-blog 4

August 11, 2018August 11, 2018 / Maarten De Brauwer / 2 Comments

We are 5 days into sampling environmental DNA of the Knysna seahorse (Hippocampus capensis) and I continue to be impressed by the landscapes and nature of South Africa. After sampling at the southern Eastern Cape we traveled to the Knysna estuary in the Western Cape. We not only collected water samples along our way, but also passed through a national park to get a look at some of the wildlife.

And oh my, how lovely that was. I might be a marine scientist, but seeing the impressive wildlife here is pretty amazing as well. Obviously seeing elephants, zebras, lions and all the other cool animals roaming around is awesome, but there is so much more than that. There’s all the different kinds of gazelles, the warthogs (might be a personal favourite) and the very diverse birdlife. Unfortunately there won’t be enough time this trip to really experience it all, so I will just have to come back!

The focus of the trip is still very much on the endangered Knysna seahorse. But what does it mean when we say that an animal is endangered? And why are the Knysna seahorse and the estuarine pipefish endangered?

The easiest way to explain what “Endangered” means, is that an animal or plant has a high chance of becoming extinct in the near future. This can be caused by directly killing the animals/plants, such as overfishing or hunting (think rhinos and the ivory trade), but also by more indirect threats. For example: if you cut down the rainforest, the animals that need the forest to live in will disappear as well, even if you do not kill the animal directly.

Swartvlei estuary

In the case of the two species we are working on, two big factors are responsible for their high extinction risk. Both the Knysna seahorse and the Estuarine pipefish only occur in a very, very small area of the world. The seahorse only lives in 3 estuaries and the pipefish in 4 estuaries in the southern tip of South Africa. They do not live in the ocean or the rivers, but only in the small area of mix salt and fresh water where the rivers go into the ocean.

The other big factor is that both species only live in a particular habitat. That is, they don’t just live anywhere in those estuaries, that would be too easy! No no, the species we study aren’t happy anywhere else than in areas where there is enough seagrass. So even though there might be a lot of space in the estuaries they live, they only live in a very small area in that space.

Can you spot the Knysna seahorse (Hippocampus capensis) in the seagrass?

What this means is that small changes to the seagrass can have a very big effect on the seahorses or pipefishes. As you may or may not know, seagrass is disappearing all over the world, including South Africa. Some of the most important causes are poor water quality, coastal development, and climate change (Here is a great site for more info on threats to seagrass meadows).

For our two species, even a small, localised decrease of seagrass means they can go extinct in those estuaries where the seagrass is affected. The estuarine pipefish has in fact already disappeared from two estuaries where it used to live. This might also already have happened to the Knysna seahorse, but there is very little information about where it used to live and where it lives now, so it is hard to be certain about this.

Hopefully our work will help to protect these beautiful, but vulnerable animals. How the results of our research might help is for one of the next mini-blogs.

Early morning water sampling

Finding the Knysna Seahorse: Mini-blog 3

August 9, 2018August 9, 2018 / Maarten De Brauwer / Leave a comment

Kleine Monde

Today was busy, so not enough time to properly write. Instead, to give you an idea of what I do all day, here is the schedule of today’s fieldwork.

6:00 – Wake up
6:30 – Drive to first site (Kleine Monde)
7:50 – Collect samples (Kleine Monde West, 2 locations)
8:10 – Collect samples (Kleine Monde East, 2 locations)
10:00 – Back at room, start filtering samples
12:30 – Drive to site (Bushmans estuary)
13:15 – Collect samples (Bushmans, 2 locations)
14:50 – Back at room, start filtering samples
19:30 – Realise samples contained more sediment than expected and that filtering will take twice as long as planned, eat food, drink some wine
21:40 – Still filtering, drink tea, lots of tea
23:25 – Finished filtering samples, time to clean up
23:50 – Off to bed!