http://en.ird.fr/all-the-current-events/live-science/(view_mode)/rss fr The IRD invites you to follow the weblogs of researchers, during their on-the-ground missions. http://en.ird.fr/all-the-current-events/live-science/tuhaa-pae/end-of-the-expedition Mon, 08 Apr 2013 00:00:00 +0200 Two short sailing days to Tahiti allowed us to clear everything and to sum up the expedition results : 1850 miles , 250 dives, 74 sites investigated and described on 7 islands or group of islands, 250 taxa of macro-invertebrates and algae, over 1000 samples of mollusks for barcoding… the analytical reports shows that we did 96% of what was programmed : thanks a lot to the crew and its captain Jean-François Barazer for this success ! If the number of sponges is quite low with 49 species, only 10 of them are already known from Tuamotu, Gambiers or Society islands. These samples will take to about 150 the number of sponges species known in French Polynesia, with a level of new species as high as 30%. This number of species is quite low if related to the size of this territory and to the great collection effort lead for this. To give a better idea of the decreasing of biodiversity towards Eastern Pacific, 200 species oof sponges could be sampled in 3 weeks in Madang’s lagoon during Nuigini 2012 expedition, which is much smaller than the lagoons from Tahiti island itself.Further investigation on the samples will be identification, chemical and biological activity investigation of the major samples on aquaculture targets, an important economic field for French Polynesia and developing countries. © Jean-Michel Boré Tuhaa pae expedition’s team (last leg, Eric, Bertrand and Sylvain are missing) http://en.ird.fr/all-the-current-events/live-science/tuhaa-pae/inventory-of-maria-islands-terrestrial-fauna-and-flora-jean-yves-meyer Sun, 07 Apr 2013 00:00:00 +0200 Two days were spent exploring the four islets of the Maria atoll and inventorying native and introduced plants. Marine and migrating birds were also observed, as well as the terrestrial fauna of the atoll.Results : 26 native plants were found during this survey, which is the first and only one after the 1934’s survey of two American botanists during the “Mangareva Expedition” lead by the Bishop Museum of Honolulu. At that time, the flora was untouched, without any coconut plantations: coconut-tree has been introduced in the 50’s. © Jean-Yves Meyer Indigenous tree : Meisosperma oppositifolia 80 years after this expedition, indigenous flora remains about the same: only one species couldn’t be found, but 10 introduced species were observed such as Hibiscus tilliaceus , lemon tree, Baringtonia asiatica … and of course the coconut tree extensively farmed on the 2 biggest islands by people from Rimatara and Rurutu until late 90’s. These introduced species have probably been brought by copra workers, when the cargo-boat traveling to Australes islands was stopping there. These islands are original by their lack of weed and decorative plants : ecological and life conditions there are specially hard on these remote atolls. © Jean-Yves Meyer Phaéton juvénile (Phaeton rubricauda) Maria is a real paradise for marine birds with several hundreds of red tailed tropic birds nesting on the soil, nesting Pacific frigate birds, and dozens of boobies (brown, red-footed and masked) with their eggs and chicks. Dozens of Alaskan whimbrels on winter leave could be seen on the beach and in the forest, as well as Pacific reef-egret, golden-plover, wandering tattlers, common whit terns and brown noddys.Among other animals of the atoll are thousands of Hermit crabs and huge coconut crabs, lizards and geckos, and the Pacific rat. Mosquitoes are badly developing on the two main islands where copra was farmed and were remain old fresh water tanks. Atoll’s lagoon is very shallow (30cm to several meters) and only allows kayaking from one island to the next one. We could see many giant clams, holothurians, see urchins but very few fishes such as jackfishes and little black tip sharks (but this is the point of view of a botanist!). One night spent on a beach there allows feeling how man remains a stranger there! http://en.ird.fr/all-the-current-events/live-science/tuhaa-pae/maria-a-lost-atoll Sat, 06 Apr 2013 00:00:00 +0200 Jean-Yves Meyer, researcher in terrestrial ecology, joined us in Rimatara, and we left to Maria an atoll and the last step of our trip. It is the opportunity for Jean-Yves to explore this atoll which has been abandoned after a copra farming trial, and to check the terrestrial flora and fauna there. On the Maria’s islands, we are closer to Rarotonga (Cook Islands) than Tahiti! We are really lucky with a great weather forecast which allowed us to dive on all sides of the atoll. We found there a beautiful barrier reef and its fall, with healthy corals in crystal clear water. Corals are all small and really homogenous in size which let us think that they might be quite recent and a recovering reef, which is quite optimistic for Rurutu and Rimatara reefs. People in Rimatara told us about a small pass on the western reef: we found it getting around the atoll, but too small and dangerous even for our small diving boat. © Cécile Debitus Codium sp. This atoll is naturally protected by it remoteness and its efficient barrier reef. The abundance of corals doesn’t let much space to other sessile organisms. We find there thus 4 species of sponges, one of them known form other atolls in Tuamotu, but it lives there hidden in holes. Below 60 meter deep the bottom is covered by a giant Codium species, many sea urchins and gorgonians are appearing on falls. Two Codium species are known in French Polynesia as edible sea weeds but lives at shallower depth on Society islands’ reefs. http://en.ird.fr/all-the-current-events/live-science/tuhaa-pae/the-small-world-day Wed, 03 Apr 2013 00:00:00 +0200 After Rurutu which let us a so-so feeling shared between magnificent terrestrial landscapes and a dull underwater reefs, destroyed by some dramatic natural event (Taramea ? Hurricane ? Global warming? Swell?) , we reached the last inhabited island of the Australes archipelago, the tiny island of Rimatara, also deprived of lagoon. © Anthony Berberian crabe mimétique (<5mm) de Cladiella sp The island is surrounded by crystal clear water, but the reefs are also more than 90% destroyed, more eroded than in Rurutu. We explored sites on every face of the Island, and on different slopes more or less steep. Diversity is found there in the small species sampled by brushing: mollusks of course, but also crustaceans. Two mini-crabs are nicely representative of this small world: the boxing crabs, which “gloves” are anemones Bunodeopsis sp. on its claws, and a small crab which mimics the soft coral Cladiella sp. which hosts it.A small but beautiful nudibranch has also been catched in blue water. © Anthony Berberian Lybia tessellata (5mm), ou crabe boxeur © Anthony Berberian Dolicholatirus noumeensis (6-7mm) © Anthony Berberian Triphoridae (8-9mm) © Anthony Berberian Trochidae (4mm) http://en.ird.fr/all-the-current-events/live-science/tuhaa-pae/some-interesting-fishes Mon, 01 Apr 2013 00:00:00 +0200 This field trip to Australes Islands gave us the opportunity to meet some rare fishes, since most Australes islands are deprived of diving facilities and have been barely studied until now. We could observe some endemic species or fishes with a restricted distribution area, as for example Plessis’ triangle fish (Cheilodactylus plessisi ) which is only known from Rapa, Marotiri and Easter Island, or the wrasse of Rapa endemic from Rapa and Marotiri. © Anthony Berberian Golden lined soap-fish (Aulacocephalus temmincki) A beautiful golden lined soap fish (Aulacocephalus temmincki ), rare in Polynesia was seen and photographed off the coast of Rapa in a cave at a depth of 57 m: this fish is more common in other subtropical areas. © Anthony Berberian A new species of Canthigaster ? Among the thousands of fishes met during the different dives, some attracted our attention with their special color pattern such as a small Canthigaster sp found in Raivavae and Tubuai. It is close to Canthigaster coronata but differs from other Canthigaster species described in French Polynesia. We observed this species several times, always on sandy bottoms at about 50m deep © Anthony Berberian An interesting velvet-fish (Caracanthus sp) hidden in coral branches Velvet fishes are small common fishes which live hidden in Pocillopora corals branches. The body of Caracanthus maculatus, a common spotted velvet fish, is covered of papilla. It is rose-grey with brown spots. The Caracanthus sp. met in Rapa, Raivavae et Tubuai has not been seen yet in Rurutu, where only spotted velvet fish seen until now. It is dark brown with some white spots on each side, and bears specially developed skinned papilla above its head, which forms a kind of Iroquois’ head-dress. Two specimen could be catch and preserved to learn some more on this species. © Anthony Berberian Wrasse Bodianus bilunulatus Wrasses also present some special characteristics: Bodianus bilunulatus has been seen only in Marquesas Islands in French Polynesia, and we met there several times on the outer slope of Rurutu between 35 and 50m deep. © Anthony Berberian Wrasse Pseudocheilinus cf citrinus Pseudocheilinus cf citrinus looks like the Pygmy-wrasse which is known from the geographically close Cook Islands, but has not been yet recorded in French Polynesia. It was often met between 40 and 50m deep, but uncommon in Raivavae’s and Tubuai’s lagoons. © Anthony Berberian Wrasse from Rapa (Pseudolabrus torotai) This observations lead us to several questions: are the morphological differences the result of a speciation process? Is the endemism, as for other marine organisms, restricted to islands or to the archipelago? Why are patterns of distribution more complex in Polynesia for some species which are widely spread in the world? Since we do not have any fish specialist aboard, we are limited to iconographic and literature comparisons. These results will be anyway presented to specialists who will evaluate the need of further studies or not. http://en.ird.fr/all-the-current-events/live-science/tuhaa-pae/no-lagoon-anymore-conditions-are-getting-more-tough Fri, 29 Mar 2013 00:00:00 +0100 We are cruising up the Australes chain of islands and reached Rurutu : this high island (as Makatea) is surrounded by a fringing reef presenting few (dangerous) passes for small boats. The bottom follows a mild slope, but this island presents different capes and bays to be explored with different expositions to the sea. The only problem is to reach the diving sites ! Alis anchored on the western coast, a good shelter from the strong south-eastern swell that nothing stops. © IRD/Cécile Debitus The dive-whatching team The small size of the island allows us to reach the different diving sites using the small diving boat, stirred by Ronald, Edwin, Simon, Franck or Mickael who secures the dive from the top : we know they care finely for us and this allow us to work free and quiet on the bottom, whatever the conditions are. If needed, they will send us spare gaz tanks (air or oxygen) if asked using a code between bottom and top people. They also keep a vhf contact with the master ship Alis. Brushing rocks and hand-sampling allowed us to rise a nice collection of mollusks and crustaceans, but it has been more difficult for larger soft invertebrates. The collection is much smaller: sponges are there (9 species, 3 common for Australes), buch much smaller than usual. They reach and can fix on hard substrate there, but cannot develop much: the sea water seems too poor in nutrients for the high filtering organisms. © IRD/Cécile Debitus Callyspongia aerizusa The sponge Callyspongia aerizusa , known from the western Pacific and New Caledonia at a similar latitude (22°27’ south) is found there for the first time in French Polynesia, on sheltered rocks from the main bay (Moreai). Phylogenetic analysis of these samples and other samples from the Queensland Museum repository in Brsibane, will help to understand how it spread throughout the Pacific ocean. Bicolor crinoids common in Australes and the tunicate Ascidia cf tapuni are often found below the rocks. © IRD/Cécile Debitus Under-water landscape in the bay of Moerai Low pressure systems in the south forced us to leave to high sea : Sunday was suppose to be a day off for all of us and specially for divers who have to eliminate the excess nitrogen stored in their body. It was impossible to remain on the anchor anywhere along Rurutu, so we are cruising around at a low speed since Saturday evening. Croissants at breakfast are a sign that we are on Sunday, but walking around on the island would have been appreciated by everybody! Eric and Bertrand will leave on the 1st of April, and John will come aboard. Embarking and disembarking to reach the island will be quite challenging and wet… if possible anyway. Marine chart of Rurutu http://en.ird.fr/all-the-current-events/live-science/tuhaa-pae/tubuai Wed, 27 Mar 2013 00:00:00 +0100 We spent 4 days in the sea surrounding Tubuai and explored 17 underwater stations chosen according to their location on the outer slope or inside the lagoon. The outer slopes are covered with live coral and include a beautiful coral diversity (15-20 different species) and many green (Codium sp, Halimeda sp) or red algae (for example Asparagopsis taxiformis). Sponges are rare and hide under slabs of rock: is it because the water is too rough, or too scarce? We will eventually find more specimens inside the lagoon, many species of which are similar to those found in the Raivavae lagoon. A species of Suberea (Verongidae) proliferates on reefs inside the lagoon: so far, we have found these living organisms on the outer slopes of the Society Islands. The analysis of the histological sections will enable us to determine whether the species are identical.The small calcareous sponge found in Raivavae was also observed in the Tubuai lagoon: it is, therefore, not endemic to Raivavae, but probably to the Austral Islands. It would be interesting to know whether it is present in the nearby Cook Islands, since the Austral Islands are part of the same marine "eco-region" as the Cook Islands. © Anthony Berberian Coral diversity on the outer slope of Tubuai http://en.ird.fr/all-the-current-events/live-science/tuhaa-pae/mollusc-story Sat, 23 Mar 2013 00:00:00 +0100 Gastropodan molluscs, widely known as snails and slugs, are among the most wonderful and diverse inhabitants of the World Ocean. Over centuries humans have been attracted by marine shells with elaborate sculptures and intricate colour patterns, they were admired by naturalists and craved for by collectors. To date, the question of “How many species of molluscs live on our planet” remains unanswered. If the number of described species of the phylum Mollusca is being estimated at around 70-75 thousand species, a large proportion of mollusc species remain undescribed. Recent efforts to census marine life identified three major sources of yet undescribed marine species. So-called “cryptic” species – complexes of species, very similar, often practically indistinguishable morphologically constitute a first source of underestimated species diversity. The use of molecular techniques for surveys on biodiversity introduced a universal tool for species delimitation based on differences in the sequences of selected DNA markers. © IRD/Eric Folcher Glossodoris atromarginata The so-called molecular barcoding technique – implicates examination of the genetic marker, the sequence of which provides an unmistakable species recognition, enabled revolutionary advancements in current taxonomical classifications, allowing the reliable differentiation of cryptic species. The second source arises from the fact that different groups of molluscs are studied very unevenly – large molluscs, attractive for shell collectors, like cones and cowries, are studied more extensively than families of small (>1 cm) and superficial looking molluscs, and yet, these families often demonstrate remarkable species richness and conceal thousands of new, still undescribed species. The third source of a number of new mollusc species, is the understudied regions of the World Ocean – unreachable abyssal depths and insular regions with unique and endemic faunas. Often geographical isolation of remote islands makes the exchange of dispersal larvae with neighbouring regions impossible, leading to biological isolation – the powerful evolutionary factor causing appearance of new species restricted to insular regions. © IRD/Eric Folcher Lima sp One such region is a remote group of islands, the Austral Islands archipelago, on the very South of French Polynesia. Previous reports suggested a high proportion of endemic species in the fauna of the southernmost of the Austral Island, Rapa (27°S). One of the goals of the Tuhaa Pae 2013 expedition is a wide scale sampling on Molluscs in shallow water localities of the Austral Islands. Together with traditional underwater collection methods, we will employ specialized techniques, the so-called “brushing” and “air-lifting”, which allow for the preferential collection of micromolluscs. All collected specimens will be preserved for subsequent molecular study (typically molecular barcoding implies sequencing of COI – cytochrome-oxydase subunit 1 fragment from mitochondrial genome). As a result of our sampling we expect a representative dataset, enabling the determination of diversity gradients and rate of endemicity of the molluscan fauna of the Austral Island. Molecular studies will provide data on phylogenetic relationships of Austral Island molluscs, and, hopefully, answer the question on the origin of the characteristic molluscan fauna of Rapa Island. © IRD/Eric Folcher Mitra sp http://en.ird.fr/all-the-current-events/live-science/tuhaa-pae/raivavae Thu, 21 Mar 2013 00:00:00 +0100 Raivavae is a high island surrounded by a coral reef and “motus” islands (islets). Water flows into the lagoon through a narrow channel to the South of the lagoon and through some breaches in the barrier reef, and flows out through a large pass to the North, at a relatively low rate currently, due to the warm weather conditions and to the low swell. Unlike the Society Islands and the islands of the Tuamotu Archipelago, the island is surrounded by a vast gently sloping plateau that drops after 60-70m, well off the coast, which is not conducive to seabed explorations beyond 40m. The outer plateau has numerous live hard and soft corals, especially octocorals (Alcyonaria) of the genus Sinularia difficult to distinguish in the field. However, the lagoon with its sandy-muddy seabed is full of patch reefs and pinnacle reefs, home to several species of sponges © IRD/Cécile Debitus New calcareous sponge on a clam : the traditional Dysidea sp and Hyrtios sp, but also, on the southern side of the island, to a calcareous sponge so far never observed in Polynesia: this yellow sponge is small: 1-2 cm. It differs macro-morphologically from Leucetta chagosensis by its osculum, from which a translucent tube extends outwards, and by its habitat, since Leucetta chagosensis mainly lives on the outer slopes of the Society Islands, whereas our new discovery likes it best on the southern side of the lagoon, living on various hard substrates: live and dead corals, clams... Histological sections will enable us to describe and identify the sponge in the laboratory. A sufficient amount of the sponge (approximately 10g) was patiently collected in order to detect a chemical fingerprint, and possibly identify the predominant molecules extracted. These compounds are secondary metabolites, which contribute to the characterization of the species (chemotaxonomy). The chemodiversity is an understudied aspect of biodiversity: the numerous molecules (active or inactive) identified in each pathway (terpenes, alkaloids...) allow us to understand the mechanisms underlying the biosynthesis of complex molecules and to develop biomimetic syntheses in order to reproduce these natural molecules in vitro and ensure a good yield. http://en.ird.fr/all-the-current-events/live-science/tuhaa-pae/overview-of-the-rapa-prospection-results Mon, 18 Mar 2013 00:00:00 +0100 We spent two days exploring the seabed of the southern, western and northern coasts of Rapa. Following on from a request by the Tavana (mayor), the research project related to the campaign, as well as an overview of our Rapa prospection results, were presented to fifty very attentive people on Sunday afternoon. The translation into the Rapa dialect was done by the village Pastor. This brief overview was also the perfect occasion to present results obtained on the molluscs collected during the first workshop in 2002 by the Muséum National d’Histoire Naturelle (MNHN) team: the number of known species has risen from 150 to 600 species, and the rate of endemicity was evaluated at 15%. This high rate of endemicity is linked to the geographical isolation of this Island, and to the poor dispersal ability of some species. © Anthony Berberian Ambience of a diving site on the southern coast: live corals and field of seaweed Regarding our prospection (16 geographical sites were explored on Rapa and 7 on Marotiri), the number of sponges described on the Islands rose from 0 to 18 species, only 3 of which have previously been described in the other archipelagos. The sponge fauna is characterized, here, by the scarcity of most species encountered only once. A dozen species of octocorals were sampled, as well as 70 species of molluscs for barcoding. A small crown-of-thorns starfish (Acanthaster planci) was observed off the southern coast of the Island: this coral-eating starfish worries Rapa inhabitants, who noted its recent appearance and who organised collective fishing expeditions in an attempt to limit its dispersal, the coral is currently in good health currently. The reserve was closed by the Pastor once the overview presentation was finished; the crew of the Alis and the scientists were then invited to share another meal with local officials and the school headmistress. We would like to thank the population and the Tavana for their warm Polynesian welcome and for the interest they showed in our work. © Sylvain Petek Attentive assembly during the presentation of our results