Reintroducing Snails () back to Tahiti – A 30 year Promise Glennon Frei Invertebrate Keeper, Saint Louis Zoo #1 Government Drive, St. Louis MO 63110

Abstract

Partula Snails were once a thriving taxa of gastropods spread throughout French Polynesia. However, due to human impact via the introduction of the Giant African and predatory Rosy Wolf Snail most Partula have been driven to the brink of . Nearly thirty years ago the Saint Louis Zoo became one of the last refuges for these displaced , and for the last three years Partula nodosa raised from six institutions across the United States are being put back into the very same valley they were rescued. This paper will describe the author’s participation in the reintroduction process.

Intro – The Plight of the Snail

Once a common sight throughout many Pacific Island forest understories, Partula snails have been pushed to the brink of extinction. At one time seventy-two species were in French Polynesia. That number is now down to sixteen (Coote et al). The main culprit in their demise is the introduction of the Rosy Wolf Snail (), a predatory snail species from the southeast U.S. disseminated across the islands as a control measure to combat the Giant African Land Snail ( fulica) that was released and wreaking havoc on the local agriculture (Clark et al).

In the mid-1980s scientists working in the field notice the indiscriminate destruction that the Euglandina were having on the local snail populations and collected as many of the species as they could (Coote et al). Sadly, on the island of Tahiti only four of the species still exist and far fewer in number (Kelly et al). The species that were collected eventually found homes in a few Zoos and Aquariums across the U.S. and Europe. The Saint Louis Zoo received their first snails in 1990 and have reared Partula nodosa until their eventual releases that started in the fall of 2015.

Zoo’s Involvement

Zoos and Aquaria have become the Ark that Partula Snails have relied on during their unfortunate exile. That Ark currently consists of fifteen zoos that are a part of the International Partula Conservation Program (IPCP) that work together to rear and to preserve the remaining Partula species. The Zoological Society of London heads the IPCP, leads the international planning of Partula, and plays a vital role by securing a field researcher in French Polynesia.

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It would be nice to say that everything has been smooth sailing, but a couple of species eventually went extinct while they waited for their return home. Those unfortunate events are tempered by the fact that there are thirteen species with an additional two subspecies still in culture after more than three decades of time. Over the last three years, approximately 7100 snails comprising of 10 species have been reintroduced. It is a truly staggering number of individuals and species in such a small window when one thinks of the process and obstacles involved to accomplish such a monumental task: coordination of fifteen institutions, Government entities, field research and funding needs.

The “Flights” of the Snail

Six U.S. institutions raise Partula nodosa: Akron Zoo, Detroit Zoo, Disney Kingdom, Saint Louis Zoo, Sedgwick County Zoo and Woodland Park Zoo. Each zoo takes meticulous care of their animals, including monthly counts of each tracked life stage that helps determine how many snails can be contributed to each yearly release. Once numbers are decided, snails are packed and shipped using tissue paper, paper towel rolls, Styrofoam boxes, and bags of water to maintain constant temperatures and then make their way to Saint Louis. There they are consolidated before they make the next leg of the trip - a 4,200 mile (6,750km) trek to Europe.

Either the London Zoo or Royal Artis Zoo then graciously accept the snails and run health screens to make sure the animals are healthy enough to be released. After a month long layover in Europe the snails make the longest leg of their journey, 9,000 miles (14,500km) to the South Pacific. The Partula landed in Faa’a, Tahiti on October 6, 2018 two calendar days after they departed the E.U. Three flights over a three-month period take the snails more than 15,000 miles (24,140km).

Meeting the Snails and Quarantine

After a couple of days acclimating to the island and meeting with the field researcher, Trevor Coote, and the local government entities we proceeded to the airport to collect the snails and bring back to the quarantine room at the Department of Environment (DIREN). Trevor, Claude Serrat of DIREN and I traveled to the airport to meet the Tahitian veterinarian Christophe Giraud who would inspect the Partula and grant them clearance to leave and be reintroduced. There was some apprehension as the airline had lost the necessary health documents and the replacements had yet to arrive. Upon examination of the snails and guarantee that paperwork was indeed on its way, we were allowed to take the snails.

Back at DIREN, we took the Partula to the quarantine room, i.e. the buildings IT server room – some things don’t change regardless of where you are – and the snails were carefully unpacked and each individual snail was scrutinized again to be doubly sure of proper health and to get an accurate count. Each snails was marked with blue enamel paint prior to shipping to differentiate from wild produced snails, but a few also needed a “touch up”. They were then transferred to one of their twenty-eight temporary housing containers and were fed by reconstituting a prepared powdered diet and smearing it on the sides of their critter keeper home. A liberal misting and a

2 layer of cling wrap over the top to retain humidity and affixing the lid finished off the nearly 4- hour process.

The bright spot during all this is that it does not appear that Partula snails suffer too much from jet lag. Of the 1,799 snails shipped, 1,790 made the trip alive. A 99.5% survival rate during shipping is astounding for any invertebrate and a tribute to each person involved developing the transfer protocol and those working with all the brokers and government entities to make sure everything went as smoothly as possible.

Over the next four days spent in quarantine, the snails were cleaned and fed twice more and again individually inspected for health. Approximately 24 hours of snail care was needed by standing in a 17°C (62°F) room. It really had me looking forward to the reintroduction and drove home the notion that conservation projects are not all fun and games, but require constant resolve to see it to fruition. The final positive note of the quarantine time was that only fifteen more snails were lost leaving us with 1775 individuals for release, a gaudy 98.7% survival rate.

The Release – Promise Fulfilled

To prepare for the release, 28 black plastic plant pots were purchased from the local home and garden store. The release pots were punched with holes so they could be suspended in the trees with twist ties. Each pot was lined with paper towels to help with humidity, wrapped in cling wrap, numbered, and marked for reference later.

Early in the morning, I arrived at the DIREN facility, began inspecting snails one last time for any health concerns, and then transferred the snails to the release pots. The snails were once again counted to ascertain the final release total. All the release pots were placed into soft-sided coolers for transport back to Papehue valley where they were collected from three decades earlier. Rodrigo Navarro, a local Tahitian and Partula colleague, picked us up in his pickup truck and we travelled to 11 miles to the reserve where the release would occur.

Once there we met with a handful of DIREN employees and a news reporter and then proceeded the approximately 0.5 mile hike up into the valley. It is a beautiful valley with a very complex habitat filled with tall trees and at times a very thick underbrush and a meandering stream running down the center. As with many of the pacific islands, invasive plants have come to dominate large swathes of the interior of the islands. The most noticeable invasive in this valley is the very large and abundant African Tulip Trees (Spathodea campanulata) that cover a large part of the canopy. The other large native tree present in good numbers and of interest to the release is the Tahitian Chestnut (Inocarpus fagifer), locally known as the Mape Tree. It was previously assumed that the dry bark of the Mape would be an uninviting climb for Partula and Euglandina. An observation and a tip from one of the local Tahitian helpers acting as snail spotters proved this inaccurate. Partula were found on the trees and higher up than what was always assumed. This has changed the release methodology to utilizing the Mape extensively.

Once the release area was reached and all interviews and general discussion were finished we proceeded to release the snails. The area was picked for the large abundance of Mape trees. A pot containing the snails were picked out and carried to the trees and cling wrap removed. Twist

3 ties were used to attach the pots to thick branches on the larger trees or to the trunks on the saplings. Distilled water was sprayed on the snails and on the tree above the pot up to 60cm (2ft) to get them moving and to encourage the snails to disperse vertically. All 28 pots were released in this manner spread out over an area roughly the size of a football field. In the end all it took was approximately 45 minutes to release the snails, make observations, pictures and recordings.

The snails are now on the own. All we can do is observe and hope for the best.

Monitoring - Observations

Monitoring counts occurred 1, 4, 7 and 10 days post release. Myself, Trevor and Eric Loeve (a French scientist who lives on the island) manned these observations. Once in the reserve what we found were almost all the snails had dispersed vertically into the trees or horizontally across the lower “canopy” the dense saplings made. In all, the first three monitoring sessions led to almost identical counts of snails

Slightly more than 70% of the adult snails were still visible at each count, with only six dead snails found during the first week. After the initial dispersal during the release the weather dried on that side of the island and the snails aestivated, refusing to move until better conditions arrived. These numbers are heartening in that the snails seemed robust enough to survive all the travel and stress of a release and still hang on with suboptimal release conditions. It would definitely have been nice to see the snails disperse and do what the snails are supposed to do, but we gladly accept having only a couple setbacks in the grand scheme of the reintroductions.

Two other observations of note include what I assume are a positive and a negative. The positive, and maybe the most impactful experience I had was following a slime trail of one of the Partula ascend the moss covered trunk of the Mape tree it was released on to a height of approximately 7 meters (21ft). While the predatory snail still occurs in Tahiti, they tend to be terrestrial. Watching the Partula climb to assumed safety, even if it means we can no longer observe them, is encouraging.

The negative observation was that one Partula snail was consumed by another introduced species, the New Guinea Flatworm (Platydemus manokwari). One Partula descended the tree it resided on and was attacked and eaten on a leaf 30 cm (1 ft.) off the forest floor. Platydemus have been purposely and accidently spread worldwide to combat invasive snail species. They have also left an ecological wake of destruction wherever they have been spread.

I left before the 10-day monitoring happened. Rain to come to the valley by then and the snails “woke up”. The vast majority dispersed out of observable range, and all things willing are doing well.

Conclusion

This was an amazing experience. Watching animals go from plastic or glass aquariums to traversing through island forests where they occurred decades before was very meaningful. We

4 conserve and educate by trade, but that field component that brings our animals back to their purpose was one of the highlights of my career thus far.

I try not to temper that feeling knowing that what we do is just a start and there are still many hurdles to clear. Euglandina and Platydemus are still threats, but one with a potential silver lining. Euglandina are nowhere near as numerous as they once were. They may have eaten themselves out of house and home on Tahiti. Platydemus may also have a redeeming quality by eating the Achatina and Euglandina as all three species tend to be terrestrial. Only time will tell.

I breezed through the entire zoo and aquaria’s involvement in the repatriation of these species. I certainly could have expanded on how much time and effort was expended for the 30 years in just keeping these animals, the three or more years of planning and coordinating for all the reintroductions and the hopeful continuation of the reintroduction program. Moreover, in the end all that work amounted to less than an hour of time to release them. In some ways, it seemed extremely anticlimactic. Nevertheless, it just goes to show what we do ex situ matters. Maybe not today or tomorrow or even three decades from now, but what we do makes an impact. Releasing more than 2000 snails in a three-year period is something we can hang our hat on, but it is still just a beginning.

References:

Clarke, B., J. Murray, and M. S. Johnson. 1984. The extinction of endemic species by a program of biological control. Pacific Science 38: 97-104.

Coote, T. 2006. A Long-Term Action Plan for the Protection of the Endemic Tree Snails of French Polynesia. (Unpub.) International Partulid Conservation Programme.

Pearce-Kelly, P., Clarke, D. and G. Mace. 1994. Partula '94: An action plan for the conservation of the family , by the Pacific Island Land Snail Group. (unpub. report): ZSL, Regents Park, London, NW1.

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Pictures:

Snails marked and in release pot. Trevor Coote with Snails in coolers. Release pots adhered to young Mape Tree.

Glenn Frei Releasing Snails into young Mape Tree Trevor Coote and Eric Loeve monitor post-release snail movement.

Partula nodosa slime trail ascending New Guinea Flatworm - Platydemus manokwari eating Partula Snail

Tahitian Chestnut tree

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