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Q PRACTICAL OCEANOGRAPHY


cryophilic (i.e. survive at low temperatures) then the crash site identification can be narrowed to a few areas. “If we find Lepas australis on the wreckage then we can be prove with certainty that the plane fell into the cool southern marine areas west of Australia.” Lepas australis, as its Latin name suggests,


lives exclusively in southern latitudes, not in tropical regions. The crustacea, which are related to Balanidea, attach themselves to floating material in the ocean by means of a stalk. Herbig and Schiffer have been working on a bio-geographical classification of many subtypes of this species from all tropical and temperate latitudes of the ocean since 2008. So, says Herbig: “We just have to see the shells to be able to say which type of goose barnacles these are.”


54 Indian Ocean clues


A more detailed analysis will enable a reconstruction of how long the barnacles have been attached to the wreckage. Researchers at Southampton’s National Oceanography Centre (NOC) who are tracking the debris also have scientific expertise that could provide clues to the path the wing part took through the Indian Ocean. The Indian Ocean contains a mixture of cold


and warm waters, with different barnacle species living in each zone. The speculated crash site, in the south east Indian Ocean, spans a junction between the habitat of two species. One is the sub-Antarctic Lepas australis and the other is the tropical and subtropical Lepas anatifera. Professor Richard Lampitt


from the NOC, said: “The crucial analysis to be done now is to determine the species of all of the barnacles on the wreckage. In addition, the size of each specimen should be noted as it is possible that the larger and older specimens will have settled when the wreckage was in a different region.” Furthermore, the chemical composition


of barnacles can provide clues to the path of the aircraft debris because the concentra- tion and ratios of some naturally occurring trace elements will vary from area to area.


Drift simulations: finding with NEMO


The NEMO ocean model was developed by an international consortium, including the NOC. The model provides full depth coverage of ocean currents, temperatures and salinities. It has also been used to track the movements of oil spills.


Professor Adrian New, an expert in Indian Ocean currents at the NOC, says that the discovery of the aircraft wreckage in Réunion might be consistent with a possible


crash site in the south east Indian Ocean, although other crash sites cannot definitely be ruled out.


Scientists from Australia’s national science agency, CSIRO, have also constructed a computer simulation model that supports the idea that debris from MH370 may be found as far west of the search area as Réunion (see https://www.youtube.com/ watch?v=PZ7yQ1u2rqw). The Australian Transport


The DNA of individual barnacles could narrow the path area even further.


Model investigation


Together this information could help increase the degree of confidence in potential debris paths inferred by models of surface currents, which are also being analysed by researchers at the NOC. Lampitt added: “Judging from photographs I have seen of the wreckage, the size of the barnacles suggests that they may have been in the water for more than a year. I am basing this on my observations of barnacle growth on scientific research equipment that the NOC deploys and recovers from the ocean once a year.” This equipment is


deployed at the Porcupine Abyssal Plain ocean observa- tory, which is 500 miles to the


southwest of the United Kingdom, as


part of the Southampton institute’s long-term observation of the area. Researchers at the oceanography centre


believe that there are two possible scenarios for the potential pathway that has been taken by the wing part: “In the first, it would have initially been carried northwards in a large ‘round- about’ of currents in the South Indian Ocean


Safety Bureau believes that the pieces would have initially stayed at the latitude of the search site, before winds and currents – known as the Indian Ocean gyre – pushed them in a north- west arc.


On where the debris could have ended up, CSIRO ocean- ographer David Griffin says: “Madagascar was probably the highest probability, and Réunion is not far from that in the scheme of things.”


– called a ‘subtropical gyre’. It would have then been swept westward, towards Réunion Island, in a relatively fast moving band of water known as the South Equatorial Current. “This westward flowing water moves


across the entire southern Indian Ocean at the same latitude as northern Madagascar but can be partly deflected towards Réunion when it meets the Mascarene Plateau at 60°E. The speed of this current varies, although it can reach up to 0.5m/s.” “An analysis of a global ocean simulation,


provided by the NEMO model gives rise to the second scenario. In this situation it appears possible that the debris could have been carried more or less directly westwards by a complex pattern of swirling currents or ‘eddies’. These are rotary current structures that travel slowly westwards,” they added. To confirm the likelihoods of these


pathways, more detailed analysis is currently under way at the NOC – including the direct tracking of surface-floating particles. However early indications on the likely timescales for these routes could be between one year for the more northerly course and two years for the directly westward one. Until scientists have been able to examine


the wing fragment and its faunal cargo, speculation about the debris from flight MH370 will surely continue.


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