The discovery of the Sodwana seahorse (Hippocampus nalu), Africa’s first pygmy seahorse

I am beyond excited to share the news that with a fantastic team of colleagues, we described a new species of pygmy seahorse!!! Hippocampus nalu, or the Sodwana pygmy seahorse in normal language, is the 45th seahorse species to be described, and the first pygmy seahorse species found in African coastal waters. It’s gorgeous and cute and very tiny.

To explain the story of how such a discovery happens, we wrote an explainer in The Conversation. Just so you wouldn’t have to do effort of clicking the link, I am also sharing the article below, which was co-written by myself, Louw Claassens, Graham Short, and David Harasti. All pictures provided are by Richard Smith.


Before you read this article, pause for a moment and look at the nail on your little finger. That’s about the size of a new species of seahorse discovered in the waters of Sodwana Bay, South Africa, which falls within the iSimangaliso Wetland Park, a World Heritage Site, in KwaZulu-Natal province.

Hippocampus nalu grows to a maximum size of just 2cm. It is the first pygmy seahorse ever discovered in African waters. Our team has conclusively demonstrated that Hippocampus nalu is physically and genetically distinct from the seven known species of pygmy seahorses. Its nearest relatives are found more than 8,000 km away in the Pacific Ocean.

Hippocampus nalu - South African pygmy seahorse, Sodwana Bay

An adult male Sodwana seahorse (Hippocampus nalu). Credit: Richard Smith

Seahorses are threatened all around the world. Many species are at risk of becoming extinct because of human activities such as bottom trawling, over-fishing, and habitat destruction. As a result, several species are listed on the IUCN Red List of Threatened Species. However, to date no pygmy seahorses are considered threatened – because we simply do not know enough about them. By discovering more species, and learning more about these tiny creatures, scientists can offer advice on how best to protect them.

Pygmy seahorses can also provide an important boost for tourism: scuba divers love these small species and are willing to travel far and wide for a chance to see them. If coastal communities and scuba divers alike are taught about the best ways to protect these species and others in the oceans, there can be huge economic and social benefits.

The most astonishing part of this discovery is that it didn’t start in a laboratory, or with keen scientific minds assessing the likelihood of finding a pygmy seahorse in African waters. Instead, it began with a photograph.

Tracking the seahorse

Dr Louw Claassens and Dr Dave Harasti arrived in Sodwana in early 2018 looking for an entirely different animal: a seahorse-like species called a pygmy pipehorse. But then a local dive guide named Savannah Olivier showed them a photograph of a very small seahorse. The scientists recognised it as a pygmy seahorse, which are supposed to live an entire ocean away. South Africa is home to four other seahorse species, but this was the first time a pygmy seahorse had been observed in South Africa, let alone Africa.

Nine months later Louw returned to Sodwana Bay, this time accompanied by Dr Richard Smith, a pygmy seahorse expert. They, with Olivier, found a pair of the tiny pygmy seahorses along a rock face at about 15m depth. The little creatures were grasping on to slivers of algae amid raging surging seas. The reefs of Sodwana Bay are exposed to the swells of the Indian Ocean, very unlike the more sheltered coral reef settings in the tropical Pacific where the other known pygmy seahorses are found.

Later they even found a tiny juvenile measuring just a centimetre in length, which was dwarfed by a diver’s finger.

Juvenile Hippocampus nalu - South African pygmy seahorse, Sodwan

Juvenile Hippocampus nalu – South African pygmy seahorse, Sodwana Bay. Credit: Richard Smith

Finding the seahorses was only the first step in describing the new species. The rest of the team now got to work. Graham Short, a researcher at the Australian Museum and California Academy of Sciences, compared the mystery seahorses with other pygmy seahorse species by looking at their characteristics under a microscope, as well as a powerful CT scanner. Dr Mike Stat, a geneticist from Australia, used genetic methods to test how distinct it was from other species. Through combined team efforts, we confirmed that the Sodwana pygmy seahorse was a new species and could give it an official scientific name.

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CT scan of the Sodwana seahorse (Hippocampus nalu). Credit: Graham Short

The name “nalu” has three layers of meaning. In the local isiXhosa and isiZulu languages it means “here it is”, to show that the species had been there all along until its discovery. “Nalu” is also the diver Savannah Olivier’s middle name. Finally, “nalu” means “surging surf, wave” in Hawaiian, which hints at the habitat the species lives in.

More to learn

The discovery of the Sodwana pygmy seahorse is exciting for more than just its scientific value. It provides new insights into the global distribution of these tiny fish and paves the way for further exploration in other locations. Only a handful of research publications focused on the ecology of pygmy seahorses exist, so anything we can learn more about these critters will help the future conservation of this unique group.

Finding a species like Hippocampus nalu also shows how little we know about Africa’s marine biodiversity, and how much more is left to discover. It highlights how important the observations of keen amateurs are to help scientists. If a keen fisherman did not consider a strange looking fish caught off the south coast of South Africa worth sharing with Marjory Courtney-Latimer in 1938, the discovery of the coelacanth, a living fossil, might never have happened.

Similarly, without a diver’s sharp eyes and an expert’s initial questions, the world would still not know that the Sodwana pygmy seahorse exists. As scientists, being open to questions from the general public not only helps inform non-scientists, but can also help us make new discoveries.

Hippocampus nalu - South African pygmy seahorse, Sodwana Bay

 A female Hippocampus nalu. Credit: Richard Smith

TEDx talk: Small critters and ocean health

Last September I had the pleasure of doing a TEDx talk in Stuttgart. The video is online now so you can check it out on TED or just watch below. The talk combines aspects of my research on small critters, biofluorescence and environmental DNA. I hope you enjoy watching it as I enjoyed doing the talk 🙂

Ambon and Halmahera fieldwork: Mini-blog 3 – Surveying Ambon’s reefs

In the previous fieldwork blog I wrote that we were about to leave on the boat to survey coral reefs around Ambon. So let me walk you through how our first week went.

Leaving Ambon took a bit more effort than expected, getting the necessary pre-departure paperwork signed off took 6 hours instead of 10 minutes, but we finally managed to leave late afternoon. We left under a rather gloomy sky, with grey clouds and scattered rain showers seeing us out of the bay instead of the bright sunshine we hoped for. But with an overnight boat trip ahead of us to get to the first sites, we could maybe wake up to blue skies.

That, unfortunately, was not meant to be…

Leaving Ambon

Gloomy Ambon skies

When I mention “dive expedition in Indonesia”, most people tend not to imagine grey skies and unrelenting rain, but the lush tropics wouldn’t be quite as lush without lots and lots of rain! Throughout the week we had plenty of rain, sometimes so much we had to postpone dives because of the limited visibility at the surface: the boat driver needs to be able to see the divers at the surface to pick them up when surveys are done.

 

But we had come to Ambon to study coral reefs, so (mostly) undeterred by the rain, we hopped in and started our work! The first thing we noticed was a conspicuous lack of…coral. We started surveys in an area with a lot of human fishing activity, and it showed, big time. We did not hear any blasts while diving, but there was a lot of evidence of dynamite fishing. Entire reefs were reduced to rubble, some places even had large bomb craters, something I had never seen before. I dread to think about the size of the bomb and the immediate impacts of its blast. A lot of explosive power is required to leave a 40cm deep, 1.5m wide crater underwater!

It wasn’t all bad news though, some places were showing slow signs of recovery, which could mean they hadn’t been bombed for a while. There were still some large fish left, nowhere near as many as there should be, but I did spot a few large groupers and emperors, and even a few adult blacktip reef sharks. We saw encrusting algae and small coral slowly starting to take hold in some places, although they were still a long way from becoming a real coral reef again. I would estimate it could easily take another 50-100 years for these sites to become a fully functional reef, even if they were left in peace and there were no other impacts.

 

After a couple of days of rain and survey dives that made our hearts ache, the team’s morale (or at least mine) had seen better days. Luckily, two things happened: we moved on to sites that had less fishing pressure and the sun started shining!

This part of the trip brought home just how rich coral reefs can be if you just use them in a less destructive way. Sites with very high and diverse coral cover, big schools of fish, lots of invertebrates, funky critters, everything you could want in a dive. This time our only regret was that the tight schedule didn’t give us time to explore each site more thoroughly. Between trying to count and identify large schools of mixed fish species, processing eDNA samples and entering data, little time was left to do anything else than eat and prepare for the next dive. Not that I’m complaining though, being able to work on reefs like this is a privilege that never gets old.

We were also privileged to see some of Ambon’s funky critters. During quite a few dives we came across ghostpipefish (Solenostomus paradoxus and S. cyanopterus), a rare sight on standard coral reef surveys. Our invertebrate expert had his work cut out counting a variety of nudibranchs, shrimp, cowries, and anything in between. Even the algae crew got more fish than they bargained for when a giant frogfish (Antennarius commersoni) decided to swim by and say hello.

 

Despite some adverse weather and a slow start, we finished surveys within the planned time and arrived back in Ambon Bay two days ago. Our two days on land were put to good use, catching up on data entry and admin, meetings, and even catching a movie last night (Joker, pretty good actually). Tomorrow we leave at first light for a longer trip. We are headed to Halmahera, an area where precious little information exists on the health of coral reefs. If all goes according to plan, I should be able to write an update from Ternate in about 6 days!

Ambon and Halmahera fieldwork: Mini-blog 2 – Logistics

I have made my way to Ambon since the last blog, where I have been preparing the last logistics with my local colleagues from Pattimura University before the actual fieldwork begins. In the last 3 days, the other team members have also started arriving, with the final team member (and master fish counter) landing tomorrow morning. The main things that had to happen before our boat leaves port (besides recovering from jetlag), was organising a detailed plan, training new team members, and preparing all the gear. 

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Cloudy Ambon days

One of the things we will be doing, is collecting environmental DNA (eDNA) to study biodiversity on coral reefs. If you want to know more about eDNA, I have written more about it here or here. In short: eDNA are tiny fragments of DNA in the water column that come from poop, mucus, etc. By filtering and analysing a scoop of water, we can tell what lives in the area we took water from. Because eDNA is such a new method, most people have not used it before. So in a great mutual benefit arrangement, our Pattimura University colleagues took us (my colleague Dom and me) out for a dive and in return we showed them how to collect water 😉

We obviously did more than just collecting seawater, we also went back to the lab to teach them the protocols on how to filter samples while avoiding contamination. Since eDNA analysis is so good at picking up the tiniest fragments of DNA, a careless brush of a fingertip can render the entire sample useless. We are collecting data from a boat instead of a high-tech lab, so being aware of how things can go wrong is absolutely crucial to get reliable data.

Tomorrow morning we set sail (start engine?) for 10 days of research around Ambon. So today we had make sure all the equipment got to the boat, for us to leave at first light in the morning. Between dive gear (including compressors, tanks, etc), survey tools, eDNA equipment, and other random practical bits and pieces, it took multiple returns trips with the pickup to get everything to the boat. Science is of course hungry work and feeding 16 people takes a lot of grocery shopping, which was luckily taken care of by our local team. Gino (our Ambon trip leader) has assured me we have an excellent chef on board, so be aware that there is a decent chance that the rest of these fieldwork blogs will mostly be about tasty Indonesian food!

As we will be on a boat for quite a while in the next weeks, I am not sure yet if I will be able to post blogs until we are back on the mainland. If I can snatch up some 4G signal along the way, you’ll be able to read an update on the fieldwork in a couple of days. Otherwise, the next blog will be online around the 11th of October.

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Sunny Ambon days