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The Mysterious Life of Mister K: A Seahorse Life History Study in Cambodia

Guest post by Delphine Duplain and Amick Haissoune, project coordinators at Marine Conservation Cambodia, in conjunction with Dr. Tse-Lynn Loh, postdoctoral research associate at Shedd Aquarium

A seahorse (female Hippocampus kuda) getting comfortable around our survey line.
A seahorse (female Hippocampus kuda) getting comfortable around our survey line. (Photo by Amick Haissoune, Marine Conservation Cambodia)

Once upon a time, there were some buoys marking the edges of our house reef off Koh Seh in Kep Province, Cambodia, thus protecting the reef from passing boats. Surprisingly, the ropes holding those buoys seem to have another unexpected purpose: a shelter for some of our fishes. It is interesting to realize how the most useful purpose of an object is sometimes totally different from its primary function. Eventually, after the first aquatic pilgrims settled on our installations, we noticed a specific seahorse living on a particular rope. Curious, we decided to monitor his comings and goings, recording all information we could about him, including his behaviors and size, and photographing his unique features. As time passed by, we got to know each other, waiting with impatience to go see him, and finding excuses to go near his rope. That’s how our intriguing visitor, a male Hippocampus kuda (the common seahorse), affectionately named Mister K, became a true member of our community. One grey morning, Mister K vanished as mysteriously as he appeared. Days passed by and with no sign of our dear friend, we started to fear the worst…

Weeks later, we encountered another male seahorse of the same species near where Mister K used to hang. Every piece of information we had – measurements and photographs – seemed to point toward the visitor being Mister K. Unfortunately, due to their miniature size and mastery of camouflage, seahorse individuals are difficult to identify from one another. They’re not as similar as two grains of sand, but close. How could we know for sure it was him? With the intuition that these enigmatic creatures were still keeping marvelous secrets from us, we joined Dr. Tse-Lynn Loh, a postdoctoral research associate jointly based at Shedd Aquarium and Project Seahorse, in search of answers to these questions. Constantly adding to the world’s knowledge on seahorses and expanding the boundaries of science in her research work in Southeast Asia, this genuine, constantly smiling “ocean trotter” was the ideal collaborator for our project.

Before our tale continues, a primordial question remains: why spend hundreds of hours under the sea observing Mister K and his relatives? Surely, it’s driven by a desire to comprehend the largest and most important ecosystem on Earth, the ocean, of which we know less about than the surface of the sun and the moon! Mostly, and more pressing, it is driven by the need to understand the long-lasting damage that some of our current actions have caused and the extent to which they affect every form of life on this planet now and in the future. Studying details of our environment will initiate actions that will counter-balance anthropogenic (human-caused) degradation and guide more enlightened conservation and management policies.

The members of the seahorse family, Syngnathidae, are found nearly everywhere, from temperate to tropical water, in a vast range of habitats – coral reefs, seagrass beds, mangrove forests, estuaries, etc. – many of which are threatened habitats. These environments play a key role in the carbon cycle, storing and transforming large amounts carbon. Monitoring their health is imperative with the exponential rise of man-made carbon dioxide emissions. For this purpose, the study of seahorses and their relatives is ideal. Sparsely distributed at a low density while displaying high site fidelity on a small territory, syngnathids are particularly vulnerable to habitat destruction and human-induced change. This sensitivity makes some species “canaries” of the ocean. By monitoring them, we can act preemptively and maybe stop or reverse the ecological free-fall of our seas.

The enigmatic Mister K hanging on his beloved rope. (Photo by Paul Ferber, Marine Conservation Cambodia)
The enigmatic Mister K hanging on his beloved rope.
(Photo by Paul Ferber, Marine Conservation Cambodia)

To understand the connections between seahorses and marine ecosystems, broadening our knowledge of this mythical species is fundamental. According to the IUCN Red List of Threatened Species, many seahorse species have never been studied in the wild and most are considered threatened or data deficient. Although some pioneering researchers have answered important questions about seahorse biology, many aspects remain unknown.  To monitor individual seahorses within larger populations, a minimally invasive tagging procedure seems to be the method to undertake. Aiming to be as gentle as possible while still allowing for monitoring, over time, of individual animals, we used visible implant fluorescent elastomer (VIFE) tags, and work completely underwater to further minimize disturbance to the seahorses. Studying seahorses in their natural environments also allows us to observe seahorses in a more holistic manner. VIFE tags are colored silicone-based material injected under the skin of target animals, such as fish, crustaceans, reptiles and amphibians. The VIFE material does not irritate surrounding tissues and is inserted in tiny amounts, thus making it suitable for tagging small animals. A month after tagging, our new friends were found again on their favorite holdfasts, displaying normal behaviors without any sign of stress. Following individual seahorses over an extensive period of time will improve our understanding of the population sizes and trends in abundance for each species we study. This precious information will then be used to inform efficient conservation policies and sustainable fishing practices in Cambodia and the region.

After we got acquainted with the seahorse (a female Hippocampus kuda), she gracefully uncurled herself so we could measure her in all her splendor. (Photo by Amick Haissoune, Marine Conservation Cambodia)
A seahorse (a female Hippocampus kuda) getting comfortable around our survey line. (Photo by Delphine Duplain, Marine Conservation Cambodia)

Seahorses are heavily traded worldwide for traditional medicine, souvenirs and aquarium display. Sadly, seahorses are not only highly targeted, but many also end up as bycatch in trawling operations, a non-selective and often destructive fishing method. Trawl boats drag large nets weighted by steel-reinforced bottom scrapers along the ocean floor. Sometimes aiming for shrimp or fishes, sometimes collecting any and all ‘biomass’ for use in making fish meal and other animal feed, these trawl boats indiscriminately collect everything in their path. Because of its unselective nature and the damage caused to bottom habitat, it is extremely difficult for an ecosystem to recover after it has been exposed to trawling. This highly destructive technique has been forbidden by most countries in coastal waters shallower than 20 meters, Cambodia included. Unfortunately, even though all coastal waters here are shallower than 20 meters, trawling happens on a nightly basis around Kep Archipelago. The interviews we conducted for Marine Conservation Cambodia (MCC) with trawling boat captains in Kep Province reveal that bycatch averages 70-80% of the total haul, making it a major issue in the struggle to save the marine habitats here. If no measures are taken to put an end to illegal fishing today, the marine life that the local fishing communities rely on will be vastly impoverished in the next generation. Thankfully, law enforcement, community-based sustainable development and conservation implementation are possible and currently happening here and all around the globe.

Seahorses have the potential to be charismatic symbols for the conservation of marine ecosystems in the 21st century. In their own splendid way they embody all we need to save in the oceans that sustain us. If we allow these creatures and ecosystems to be devastated, it may well contribute a serious downturn in our evolutionary prosperity in the long run. On the other hand, by monitoring them more thoroughly we will be aware sooner of environmental changes and be able to take action. Stewardship and restoration of these marine ecosystems will be the chance for Mister K, his friends and their offspring to live happily ever after.

Join us if you want to be part of the seahorse revolution and save the Kep Sea! Visit www.marineconservationcambodia.org for more information.

Guest bloggers Delphine Duplain and Amick Haissoune are project coordinators at Marine Conservation Cambodia (MCC). MCC participates in iSeahorse Trends monitoring and just started a seahorse research project with Shedd Aquarium‘s postdoctoral research associate, Dr. Tse-Lynn Loh, off Koh Seh, Cambodia.