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Our Planet Reviewed - Expedition Papua New-guinea :: Rubriques

Our Planet Reviewed - Expedition Papua New-guinea

Field_work

Marine mission

Everything starts with the satellite

 

 

Just like the land-based expedition, almost two years of preparation have gone into setting up the marine component of the expedition. This work involved researchers, technicians, students, volunteers, professional fishermen, artists and naturalists, among others. In total 111 people will take part in the marine part of the expedition, with on average 70 people present in the field at the same time. However, despite the number of people involved, choices had to be made in prioritising the organisms to study. Work will therefore focus on molluscs and crustaceans, which are predominantly benthic invertebrates, as well as algae. The marine component of the expedition is not limited to the sea itself, mangroves will also be studied, along with other areas containing seawater, sometimes beyond tidal areas (such as marine lakes, etc.). 

During the planning stages of the expedition, sites of potential interest were selected by analysing satellite images of Madang Province. 34 sites were selected based upon assumptions about the diversity of habitats and the number of species likely to be found there. The first fortnight of the expedition will be spent checking that these assumptions are correct, and that the communities of organisms we expected to find are indeed present in the areas selected. Other areas will be explored, according to the discoveries made during the first collections. 

 

Collecte d'échantillons de coraux

Collecte d'échantillons de coraux

Madang - Papouasie-Nouvelle-Guinée - Collecte d'échantillons de coraux, sur la pente externe du lagon de Madang [© Xavier Desmier / MNHN / PNI / IRD].

 

How you collect says a lot about you

 

 

Collection methods depend upon the target location: at depths of up to 30 to 40 metres, divers will visually select specimens and will use equipment such as samplers (a sort of underwater vacuum cleaner), nets or brush baskets (baskets above which small rocks are scrubbed to remove organisms attached to them). At depths below which divers can go (restricted to around 40 metres for safety reasons, due to the remoteness of the site), trawling techniques will be used. At depths below 150 metres, beam trawl and dredging will be the key tools. Nevertheless, unlike trawling nets used for fishing, nets will be rigged so as to collect the layer above the bottom, and to let fish escape.  

The Alis, the IRD’s science vessel will be the offshore expedition’s secret weapon. The trawler is 28 metres long and is equipped with a moving gantry and two fishing winches, it is also a research station, with a wet lab for filtering samples and a dry lab where samples can be observed and photographed. 

 

While specimen collection is taking place, small ‘colonisation modules’ will be placed on the seabed, these will gradually become a habitat for small fauna. A year later, once these habitats have become sufficiently mature and representative of organisms living in the area, they will be retrieved and specimens will be collected and recorded in an inventory. The advantage of this highly standardised, quantitative approach is that data can be cross-referenced with the data collected during the expedition, as well as with data collected from other regions around the world. 

With analysis of satellite images, naturalists’ inventories and quantitative approaches taken, rarely has such a comprehensive range of methods been deployed on one single site. 

Despite the scale of the means that will be deployed, the environmental impact of the expedition will be minimal. 

Specimens of emblematic species (such as sharks, dugongs, whales, dolphins, turtles, sea birds, etc.), will not be taken, and all specimen collection will be kept to a strict minimum. Furthermore, the species targeted are not considered to have commercial value. Finally, the habitats where sampling will take place will not be significantly disturbed. As such, the area covered by the hundred or so trawls planned during the expedition will be less than the area covered by one single commercial trawl. 

 

 

Le "laboratoire"

Le "laboratoire"

Madang - Papouasie-Nouvelle-Guinée - Le "laboratoire" mis en place pour la durée de la mission, dans les locaux de la Divine Word University à Madang [© Xavier Desmier / MNHN / PNI / IRD].

 

Processing and analysing samples

 

Once collected, samples will be sieved in clean seawater, in order to separate them according to size (known as fractionation). 

A first analysis will be made at the ‘Divine World University’ in Madang, whose field laboratory is equipped with around thirty workstations. The fractions containing the largest specimens (around 3 mm and larger) will be sorted by the naked eye, while others, which contain most of the interesting species, will be sorted using a microscope. The most interesting organisms will be photographed, and tissue samples will be taken for DNA sequencing at a later date. These sequences will be added to the ‘Barcode of Life’ Consortium database, which is a project that aims to identify plants and animals through the sequences of some of their genes, which will be used like a bar code. One of the major challenges of this work will be to bring together the morphology of specimens and this molecular bar code, the two methods have advantages and disadvantages for species identification.  

Specimens will then be preserved in alcohol or formalin solutions, before being sent to the expedition’s various partner institutions. This processing, which is essential to ensure the preservation of samples so that they can be analysed at a later date, has the disadvantage of damaging specimen colouring, although today this problem is solved by digital photography, as scientists are able to create photo libraries of living animals, which can be consulted, along with the corresponding specimen, during analyses carried out at a later date. 

The specimens collected during the expedition to Papua New Guinea will therefore be linked to a great deal of data: the geographical location, a description of the collection site and its ecology, macro photography, DNA sequencing, etc. 

After the expedition has returned, samples will be sorted a second time in order to be classified by family, then sent to specialists with species‐level taxonomic expertise. This network of scientists, which has been built up over the course of previous expeditions is essential for the analysis of collected specimens. Nevertheless, this analysis will take several years: a recent study has shown that the average time between collecting the first specimen of a new species and the publishing of its description in scientific literature is 21 years. The expedition is just the start of a scientific adventure.