Algae Group Expeditions: Giant clams, cryptic algal diversity and trophic structures: Our expedition to Palau (Micronesia) after a quick stint to Japan

Frithjof C. Küpper and Eleni Kytinou

We have recently completed a two-week expedition to Palau (Micronesia, tropical western Pacific), following 4 days visiting Frithjof’s friends in Chiba and Tokyo (Japan). The objectives were

(1) To conduct some preliminary work investigating the photonics of the algal-clam symbiosis the planet’s largest molluscs, Giant Clams (Tridacna gigas);

(2) To assess Palau’s cryptic macroalgal diversity using the Germling Emergence Method[1], developed by Akira Peters in Roscoff – this consists of collecting substratum samples during dives using sterile tubes, which are then subsequently incubated under suitable culturing conditions in the lab allowing to isolate any developing algal outgrowth into unialgal or even clonal cultures. On other occasions of our expeditions since 2007, this has resulted in detecting numerous new records and, in some cases, species new to science (e.g. from Malaysia, the Arctic and Antarctic, Easter Island, Cyprus and Greece).

(3) To conduct visual surveys along transects in order to study the food web structure within the framework of Eleni’s PhD research.

On March 30, Frithjof flew from Aberdeen to Tokyo-Narita and spent the next 2 days with Yusai Itoh and Tatsuo Kaiho. Yusai and Frithjof had been postdocs together in Alison Butler’s lab at UC Santa Barbara, while he had collaborated with Tatsuo on iodine-related research[i]. Eleni followed 2 days later – Tatsuo and Frithjof were waiting for her at Narita Airport, and after a quick visit to Tatsuo’s beautiful house and garden in Chiba, we were met in Tokyo by Mikako Inada (Saito), a documentary film maker specialized in penguins whom Frithjof had befriended in the Falkland Islands back in 2010. Mika was an excellent guide – we spent the first evening dining together in Ginza. The night was very short – we got up at about 1.30 am for being in time for the tuna auction at the Tsukiji fish market. We had to wait for around 3 h until we were let into the auction. Outside the auction hall was a frenzy of trucks, forklifts and traders rushing around. Inside were around 1,000 deep-frozen tunas (mostly Bluefin) from around the world. Within around half an hour, the auction was over – a typical price for a Bluefin tuna was around US$ 10,000. This auction is held 3 times weekly. No surprise fewer and fewer top predators are left in the world’s seas – as even the tuna trader, who gave an English-language introduction to us prior to the event, had to admit. After the auction, we headed back to our hotel for another 2 h of much-needed sleep before a day of sightseeing around Tokyo – the Buddhist temples and Shinto shrines of Asakusa, and then a cruise down the Sumida River to the Odaiba district, which is built on reclaimed land in Tokyo Bay. All this in beautiful spring weather – it was Sakura (cherry blossom) season! In the evening, we saw the illuminated cherry blossom around the Imperial Palace, followed by our farewell dinner from Mika and Tatsuo.

The next day, we re-visited the Tsukiji fish market – this time the Inner and Outer Market. Pretty much everything in terms of marine animal diversity on the planet is on sale here. We then visited Yasukuni, the Shinto shrine where Japan’s war dead area honored (the shrine has repeatedly caused controversy with neighboring Asian countries, since the enshrined include convicted WW II war criminals – especially when it was visited by Japanese leading politicians). After a bit of rest, we headed to Narita Airport, where we met up with Dan and Aileen Morse, who had been traveling around Japan for around a week – Frithjof had been friends with Dan and Aileen ever since they met in Roscoff in late summer 1999, when he helped them collect the red alga Asparagopsis by snorkeling. Dan, Aileen and Frithjof had been discussing about a trip to Palau since around 2010 – Dan and Aileen had been working in Palau since the 1980s, almost a decade before this former US Territory became independent in 1994. They had been trying to develop a project (and, critically, to find grant funding) for a project on the mollusk-algal symbiosis since 2015. The trip finally came to reality when during Frithjof’s latest trip to California in December 2016, he visited them in Santa Barbara and they decided during their first evening together “now or never – we live only once – let’s go”.

And here we were, at Tokyo’s Narita Airport, boarding a flight to Palau… after 5 hours in the air, we landed at the small island country’s only airport about 1 am. A driver waited for us and took us to our accommodation.

After sleeping in the next morning to catch up on missed sleep after 3 short nights, we met at the Aquarium of PICRC (Palau International Coral Reef Center) and discussed plans and arrangements. Travelling independently, we were joined by Neal Hooker, long-time group member of Dan’s and Aileen’s lab (and friends with Frithjof since December 2000), Dan’s cousin Michael Gochfeld, an environmental toxicologist and ornithologis and his wife Joanna Burger, ornithologist and behavioral ecologist at Rutgers University, as well as Dan’s former grad student, Danny deMartini and his wife Caitlin.

Since everybody was still quite tired, we decided not to go diving or snorkeling, but had an excursion inland on Palau’s big island, Babeldaob. We explored the Ngardok Nature Reserve and were fascinated by the abundance of pitcher plants, clubmosses (Lycopodium sp.) and orchids – with large fruit bats flying above us. A bit further on, we reached Palau’s parliament in its capital, Melekeok (which consists only of the government buildings, nothing else), via a lengthy dirt track through the jungle – we figured later that this was due to poor signposting, there was indeed a more convenient, paved road… The parliament and other government buildings, with Greek columns and neoclassicist architecture, were modelled upon the US Capitol in Washington DC. We were particularly amused by depictions of the Money Bird (Delerrok) on the walls of the Palau capitol. Back in the capital, Koror, a magnificent Indian dinner at the Taj followed.

The next day, we got into the sea! Dan had arranged for a boat with skipper from PICRC, who took us to one of Palau’s many spectacular marine lakes. On the way, we stopped at a WW II Japanese gun emplacement and a resting site of sea snakes (which Dan had found during a previous trip) – but the snakes were obviously away (at sea). (They subsequently made appearances for Joanna – seeing one stretched-out sunning at full length, of nearly 2 meters!) and for Dan – when they wee apparently mating.) The marine lake was mostly surrounded by one of the famous Rock Islands, except for a small exit channel to the surrounding sea. Indeed, a very unique ecosystem – a coral reef community in the marine lake, and dense tropical rain forest on the Rock Island around it. The input of terrestrial biomass, wood and leaf litter, combined with very tranquil waters created very special conditions. We spent several hours snorkeling and were totally left in awe. After lunch on the boat, we went to another marine lake site closer to Koror and PICRC, for another round of snorkeling with a large abundance of fish and many Tridacna crocea (boring clams) in coral blocks and lime stone in shallow waters. Giant (Tridacna gigas) and boring clams (T. crocea) have an amazing diversity of brilliantly colored patterns. The origins and functions of these colors has been a very successful research area in Dan’s lab for years. These colors are not due to pigments, but entirely due to the reflective properties of membranes in the clam mantle tissue. The greater proportion of the light, however, is not reflected, but directed (via a process called Mie forward scattering) deeper into the clam tissue where it exposes symbiotic microalgae with photosynthetically active light.

The next day, we explored two more sites in the southern, outer lagoon by snorkeling – Ulong Channel and south of Ulong Island. The reefs that we encountered there and very much throughout the entire trip were in excellent shape, with close to 100% cover by healthy corals and no trace of coral bleaching.

10 days of intense scuba diving followed. Some of the sites visited have a mythical reputation among scuba divers throughout the world – including Blue Corner and Blue Hole. Again, the large diversity of marine life in nearly pristine coral reef systems was stunning. Eleni managed to conduct a large number of transects for her PhD, and Frithjof collected numerous substratum samples, which are now being incubated for algal isolation work by Akira. Particularly useful for Eleni’s studies was the large abundance of top predators, testimony to the absence of intense fishing pressures

On several occasions, we came across traces of the dramatic events of World War II in Palau – one day, we dived at a Japanese ship wreck west of Babeldaob Island which had been sunk by American forces. On another occasion, on an afternoon snorkeling and kayak excursion around Koror, we found the wreck of a Japanese Zero fighter aircraft in very shallow water! Close to the one of the entrance channels towards PICRC and Koror, we came past a Japanese gun emplacement. Some of our dive sites (e.g. Blue Corner) were close to Peleliu Island, which was heavily fought over between Japanese forces and U.S. Marines, resulting in one of the worst losses of life (> 20,000) on a single island in the Pacific War. Given what a peaceful place Palau now is, it is hard to imagine what occurred in and around these islands 73 years ago.

Thank you, Dan, for organizing such a marvelous expedition, and thanks to you, Aileen, Neal, Danny, Caitlin, Joanna and Mike, for being such a pleasant team! We will be working hard on the follow-up work in the lab back home to make it a success.

[1] Peters AF, Couceiro L, Tsiamis K, KüpperFC, Valero M, 2015: Barcoding of cryptic stages of marine brown algae isolated from incubated substratum reveals high diversity in Acinetosporaceae (Ectocarpales).- Cryptogamie-Algologie 36(1), 3-29

[i] http://www.scienceinschool.org/2013/issue27/iodine

http://onlinelibrary.wiley.com/doi/10.1002/anie.201100028/full

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Frozen lakes and taiga landscape in northern Russia near Arkhangelsk

Northern Lights in the Russian Arctic on the way from Amsterdam to Tokyo,
roughly between Novaya Zemlya and Norilsk

Narita-San, Shingon Buddhist temple

Lunch with Yusai in Narita - Kampai!

One of Chiba's landmarks, the suspended monorail (for those who know the Wuppertaler Schwebebahn in Germany, the parallel is obvious!)

Chiba's reconstructed castle

One of Chiba's pretty, artistic sewer lids

Cherry blossom in Tatsuo Kaiho's garden, Chiba

Tuna auction, Tsukiji Fish Market, Tokyo (foto: Eleni Kytinou)

Cruise on the Sumida River from Asakusa to Odaiba, Tokyo

Evening walk to watch the cherry blossom (Sakura) at the Imperial Palace, Tokyo

Yasukuni Shrine, Tokyo

After our overnight flight from Tokyo to Palau: First morning at PICRC, discussing plans

Orchid in the interior of Babeldaob Island

The Palauan government building, Melekeok

Japanese WWII gun emplacement at the entrance to Koror Harbor

Entrance passage to a marine lake in one of Palau's Rock Islands (foto: Eleni Kytinou)

Marine lake in one of Palau's Rock Islands (foto: Eleni Kytinou)

Marine lake in one of Palau's Rock Islands
- note the large amount of wood from the surrounding tropical rainforest

Marine lake in one of Palau's Rock Islands (foto: Eleni Kytinou)

Crown-of-thorns starfish, marine lake in one of Palau's Rock Islands (foto: Eleni Kytinou)

Jay, our skipper, driving one of the PICRC boats (funded by Japanese development aid) (foto: Eleni Kytinou)

Fusiliers (foto: Eleni Kytinou)

The endangered humphead wrasse (Cheilinus undulatus) (foto: Eleni Kytinou)

Fusiliers surrounding us (foto: Eleni Kytinou)

Boring clam (Tridacna crocea)

Sponge

Sunset at PICRC, Koror

Intact coral reef, Ulong Channel

Giant clam (Tridacna gigas) (foto: Eleni Kytinou)

Details of giant clam (Tridacna gigas) (foto: Eleni Kytinou)

Hawksbill turtle (Eretmochelys imbricata)

Aileen snorkeling above coral reef, Ulong Channel (foto: Eleni Kytinou)

Rainforest, Ulong Island

Barringtonia asiatica, a tree with fruit containing a potent neurotoxin
(used for traditional fishing in some Pacific islands), Ulong Island

Ulong Island

Palauan Rock Island scenery

Needlefish or halfbeak

Experiment by scientists based at PICRC

Sponge

These corals must be centuries old!

Neal on the PICRC boat

About half of our team on the PICRC boat

Return to PICRC

Traditional Palauan long house, Palau National Museum, Koror

Seagrass meadow during our nighttime snorkeling excursion

Eleni snorkeling at night

Christmas tree worm in seagrass meadow

Ascidians on seagrass leaves (foto: Eleni Kytinou)

Fruit bat above the rainforest in Babeldaob at dusk

The number and size of pitcher plants we encountered was amazing - like so much else!

Former mining area in the interior of Babeldaob

Trail in the rainforest, Babeldaob

Sea snail in seagrass meadow at night (foto: Eleni Kytinou)

Siganus sp. (Spinefoot), a herbivorous fish, in seagrass meadow (foto: Eleni Kytinou)

Pneumatophores of mangrove trees, east coast of Babeldaob

- with the capitol of Melekeok in the background

Hike to the Ngardmau Water Fall, Babeldaob

River downstream of the Ngardmau Water Fall, Babeldaob

Ngardmau Water Fall, Babeldaob

Fish eggs in pool beneath the the Ngardmau Water Fall, Babeldaob (foto: Eleni Kytinou)

Ngardmau Water Fall, Babeldaob (foto: Eleni Kytinou)

Fish in pool beneath the the Ngardmau Water Fall, Babeldaob (foto: Eleni Kytinou)

Starfish at night in seagrass meadow near Koror (foto: Eleni Kytinou)

Christmas tree worm & coral at night in seagrass meadow near Koror (foto: Eleni Kytinou)

Eleni diving at Blue Corner

Collecting a susbtratum sample

Eleni diving at Blue Corner

Dropoff at Blue Corner...looking up

Dropoff at Blue Corner...looking down over the cliff edge

(Translation from Greek:) "Do your work - it's a good spot" - "Let's go to 10 m and start"

Eleni laying her transect rope at 10 m depth

Ascidians

(foto: Eleni Kytinou)

The typical rainstorm at about 5 pm!

Eleni changing scuba tank before the rainstorm hit us

One of our dinner venues in Koror

Free-swimming nudibranch, seen while snorkeling at night (foto: Eleni Kytinou)

Skull of a saltwater crocodile, found while snorkeling at night

German Channel

On the PICRC boat

Green turtle (Chelonia mydas) sleeping (foto: Eleni Kytinou)

Outer reef slope

Eleni observing a grey reef shark (Carcharhinus amblyrhynchos) - Bue Corner

Grey reef shark (Carcharhinus amblyrhynchos) (foto: Eleni Kytinou) - Blue Corner

Eleni with the skull of the saltwater crocodile
which Danny had found while snorkeling with us a few nights before

Mud skipper in a mangrove on the east coast of Babeldaob

Thalassodendron, a seagrass in the lagoon on the east coast of Babeldaob

Preparing herbarium specimens at PICRC

(foto: Eleni Kytinou)

Details of a giant clam (foto: Eleni Kytinou)

Subterranean passage linking the Milky Way marine lake to the surrounding sea
- at low tide (at high tide this is under water!)

(foto: Eleni Kytinou)

The Milky Way marine lake
has its name from the fine-grain limestone particles suspended in its waters

Eleni in the cockpit of a WWII Japanese Zero fighter (the most common Japanese WWII aircraft model, which was also used for attacking Pearl Harbor) in a shallow lagoon near Koror