More fieldwork discoveries in corona times: Sangihe

In the previous blog I described how my colleague Alessia and me explored Alor, on a mission to collect environmental DNA and study Indonesia’s remote reefs. I am still stuck at home in corona times, so what follows is the next leg of our trip. After we left Alor, we headed to an island that’s been a tempting dot on Indonesia’s map for a while: Sangihe. This particular trip was supported by a National Geographic grant to investigate Indonesia’s remote reefs.

Map

The tiny speck on the map that is Sangihe Island

To get to Sangihe, you have to pass through Manado, from there you can either take a long ferry ride or a tiny plane very early in the morning. Flying to the island is a great way to admire the volcanic activity that has formed the islands. Multiple volcanoes surround the airport in Manado and you fly over a few more dotted in the Celebes sea before landing in Sangihe, which has its own large volcano (Gunung Awu).

Sangihe fisherman

Fisherman in Sangihe. Photo credit: Maarten De Brauwer

The island itself is gorgeous, covered in forest with deep blue water around it. Being so remote, the place gets few divers, so dive facilities are nearly non-existing. When we were there (March 2020), the only place to rent equipment was the tourist info centre in Tahuna. Jemmy, who runs the shop is a great guy who went out of his way to help out were possible. Logistics were not quite on point yet since he only started in the scuba business a few weeks before we got there, but fieldwork logistics rarely are on point, so we still got to explore and collect the data we needed.

 

Sangihe

Sangihe boat views. Photo credit: Maarten De Brauwer

What stuck with me most about the sites, is the incredible visibility, which was 30m at the worst of times and up to 50m at some of the best spots. Otherwise, the health of the reefs was not as good as I hoped it would be. Some sites had extensive dynamite damage, others looked like they had bleached, and the northern sites were strangely devoid of coral, but also lacked the evidence of any typical human impacts. Bare in mind that we were exploring, and neither our fixer Jemmy, nor the boat driver had taken divers or snorkelers to most of the places we sampled. So there was a lot of searching, looking for spots, and the times we got it right, diving was as good as some of the very best Indonesia’s got to offer.

Sangihe island_boat_cave

Not a bad place to sample eDNA. Photo credit: Maarten De Brauwer

One of the cooler experiences during our time in Sangihe was exploring a small freshwater creek that entered the sea at the beach where we were having a surface interval. This small, fast-flowing river wasn’t only absolutely stunning to look at, it was also home to some very exciting fish life. Besides some very cute blue streamgoby (Sicyopterus lagocephalus), it also sheltered a healthy population of freshwater pipefish (Microphis retzii)!!! While I knew they existed, I had never seen them myself, so discovering a creek full of them definitely made my day!

Unfortunately, the next leg of the trip was cancelled due to the spread of COVID19. We were planning to head to an ever more remote island (Pulau Talaud), but the risk of getting stuck there grew a bit too serious. We managed to get a short sampling trip in at the more accessible Bangka island, but eventually had to cut our time short there as well. After only 2 nights on the island, we were told by both the university and friends in the government that the safest course of action would be to leave the country and head back to Europe. Where, at the time of writing, I still am…


A small word of warning for those of you reading this and feel like going for a diving adventure. Sangihe is proper frontier diving with lots of exploring to do. The island has few other sources of income than fishing and coconut farming, so tourism could boost livelihoods in the areas. Just be aware that safety protocols are not as well-established as they are in other, more touristy areas of Indonesia. You should be an experienced scuba diver who can deal with strong currents, basic conditions, and limited to no safety backup from operators.

Fish market Tahuna_yellowfin tuna

Yellowfin tuna for sale at Tahuna market. Photo credit: Maarten De Brauwer

Fish market Tahuna_tuna head

Tuna head was had. Photo credit: Maarten De Brauwer

Fishmarket

A man and his skipjack tuna. Photo credit: Maarten De Brauwer

Guestblog: Environmental DNA allows for the detection of cryptic seahorse species

I’m very proud to publish this guestblog by Georgia Nester. Georgia is a PhD-candidate at Curtin University, where she focuses on the use of environmental DNA on species that are otherwise hard to study. She has just published her first paper, which could be a game changer on how we detect and study seahorses and their relatives in the future.


Seahorses (members of the Syngnathidae family) have never been detected using environmental DNA (eDNA), despite the fact that globally there are 14 species classified as “Threatened” by the IUCN. We compared the ability to detect a wide range of fish including Syngnathidae of two existing fish metabarcoding assays (= methods to detect eDNA and two new fish metabarcoding assays which we developed. With our new assays, we detected three Syngnathidae species in eDNA survey of the Perth metropolitan area (Western Australia), while the existing assays did not detect any Syngnathidae. These detections include the seahorse species Hippocampus subelongatus and Hippocampus breviceps, which represents the first time a seahorse has been detected using eDNA.

 

H subelongatus

The West Australian Seahorse (Hippocampus subelongatus). Photo credit: Maarten De Brauwer

With increasing human pressures and climate change resulting in a continuous decline of global biodiversity, there is a growing demand for rapid and sensitive conservation and monitoring programs. Using traditional methods, accurate data on species presence/absence and distribution is often difficult to obtain in aquatic environments. Environmental DNA metabarcoding is an increasingly popular solution. eDNA metabarcoding is capable of revealing what species are present in an environment by detecting traces of DNA they leave behind in the environment (e.g. shed skin cells, scales, blood, faeces etc). While eDNA metabarcoding surveys have been applied to a wide range of aquatic environments, no one has reported the detection of a seahorse to the best of our knowledge.

Many Syngnathidae species are considered threatened, however many more species (over 30%) lack the data necessary to assess their extinction risk. With the risk of a ‘silent extinction’ for many Syngnathidae species, the design of a non-invasive method for monitoring and managing these cryptic species may be critical to their survival. False negatives (failure to detect a species when they are in fact present) are significant in conservation management. For this reason, we aimed to determine if the Syngnathidae family (seahorses, seadragons and pipefish) were being inadvertently missed in current eDNA surveys.

H breviceps (1)

Camouflaged species such as the shorthead seahorse (Hippocampus breviceps) can be hard to detect with the naked eye. Photo credit: Maarten De Brauwer

Australia is home to 128 species of Syngnathidae in 40 genera, 65 of which are found in Western Australian waters. The Perth metropolitan area in Western Australia was chosen as our study site as it encompasses several habitat types, including brackish and salt water. We sampled from five locations across the Perth metropolitan area and processed the samples back at the TrEnD Laboratory in Curtin University. The results of this study have recently been published in the scientific journal environmental DNA.

In total, we detected four species of Syngnathidae using our newly developed metabarcoding assays “16S_FishSyn_Short” and “16S_FishSyn_Long”. The Syngnathidae species we detected were the Western Australian seahorse (Hippocampus subelongatus), the shorthead seahorse (Hippocampus breviceps), the spotted pipefish (Stigmatopora argus) and the tiger pipefish (Filicampus tigris). With Syngnathidae populations declining due to exploitation for the aquarium trade and habitat degradation, we have shown that eDNA methodologies are capable of detecting Syngnathidae taxa in the environment. This will help inform conservation and management strategies by providing a much-needed non-invasive method for monitoring these populations. Importantly, our study represents the first time a seahorse species has been detected using eDNA methodologies.

H subelongatus_Dave

The Western Australia seahorse (Hippocampus subelongatus, one of the first seahorse species to be detected with eDNA. Photo credit: David Harasti

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.

CT_Hippocampus_nalu

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