Barnacle Growth on MH370 Debris is Consistent with a 7th Arc Crash Site in Tropical Waters

Abstract

It has been ten years since Malaysian flight MH370 went missing on March 8, 2014. We know it crashed in the Indian Ocean because westward surface currents carried at least 30 pieces of debris drifting to the shores of the Mascarene Islands, Madagascar, and the African coast. In 2015, the first two pieces of MH370 debris were found, colonized by barnacles. The first was a “flaperon” found July 29, 2015 on Reunion Island. The second barnacled piece “Roy” (from engine stencil “Rolls Royce”) traveled the farthest and fastest of all debris found so far. It was photographed December 23, 2015 at Mossel Bay in South Africa covered in dying barnacles. It was found nearby again in March 2016 and recovered, but without the barnacles. In attempts to narrow the crash site origin, early reports on the growth rate of flaperon barnacles assumed that they attached and grew in the cold waters near the latitudes along the radius of the SATCOM 7th Arc being extensively searched at the time. Later mineral ratio and oxygen isotope analysis for growth temperature gave puzzling results showing that growth began at the warm end of the 19-25C reproductive range rather than the expected cold water origin. This paradox conflicted with the active search zone, and so the barnacle evidence has been mostly dismissed. New analysis of the growth rate indicates that the barnacles on both pieces were likely only weeks old rather than the 16-21 months since the crash. This is consistent with the reproductive range in temperate waters if MH370 crashed in tropical waters, not cold. Barnacle growth has previously been combined with drift modeling to help narrow the search range, based on how long the barnacles had been attached. Observation of barnacles growing on the flaperon now show that they proliferated after the the debris first reached land. These developments in both barnacle growth and drift analysis are a good match for a crash site at the acoustic anomaly detected directly on the 7th Arc near the coast of Java.

Introduction

The purpose of this report is to provide new information to assist investigators in selecting specific areas to resume the search for MH370. Only by recovering wreckage from the crash site will the true cause of the disappearance be revealed. Familiarity with the search up to this point is expected of the reader, so the focus will be on the background of barnacle and drift research done in the last decade.

Searches for MH370 have been focused on the southern section of the 7th Arc. That is the radius distance determined by timing the light speed of signals to a satellite over the equatorial Indian Ocean relaying the 7th and final handshake ping from the plane. The crash site is almost certainly within gliding distance of the 7th Arc, but the latitude is unknown. Timing of the previous six arcs seemed to fall on a curve that would match a straight flight path south that was tangent at the 2nd Arc near the equator. We know that the first two points are not on that curve due to a major turn south. Still, an assumption of no more turns (after navigating waypoints) spawned theories that the plane continued flying unpiloted. Reaching the 7th Arc without turns before fuel exhaustion requires the maximum efficiency of Long Range Cruise mode at high altitude. Solving for a match with satellite data could also only be done for a simple path without turns. Based on these assumptions, consensus estimates of search latitude along the 7th Arc were around 38 degrees south in 2015, and are currently around 34S, some 2,000 km west of Australia.

Reports of barnacles on a flaperon from MH370 got quite a bit of news coverage. Photos showed gooseneck barnacles. Several media reports included suggestions from marine biologists that the cold water subspecies lepas australis which inhabits cooler waters south of 35S could help confirm the active search zone, while the more widespread lepas anatifera would not. Other visual analyses of the photos included lepas indica (named for its habitat north of the equator near India but also found at similar latitudes south around Madgascar). Another is lepas anatifera striata known for a stripe of molting spots on the shells. There may have been a mix of these very similar temperate species on the flaperon.

As Reunion is a French island, the flaperon was quickly flown to an army base in Toulouse, France for further investigation. The French DGA report on the flaperon was released as Appendix 1.12A-2 to the July 2, 2018 Malaysian ICAO Safety Investigation Report, completed June 30, 2016. The first barnacle analysis was by Dr Joseph Poupin on Aug 15, 2015, seen as appendix 2.6a to the same ICAO report. Just two large barnacles were sampled plus many smaller ones, identified as lepas anatifera striata. The largest specimen measured a shell capitulum (overall length) of 36mm, the other 19mm. Optimum reproductive range was noted as 18-25 degrees C. Using a novel method specific to MH370, the growth rate was estimated by referencing three data points from a 1958 study of a different species showing average shell sizes of 8, 21, 25 mm at 8, 40, 107 days. A logarithmic curve was approximately fit through three points, and the age of the 36mm shell was extrapolated to a precise 476 days, just 32 days after the crash. This appeared to provide a near exact timing match, allowing for the larvae to attach and begin shell growth. Dr Poupin emphasizes, “This estimate, although very approximate and based on limited data, reinforces the idea that this part could belong to the missing aeroplane.”

Analysis of the calcium carbonate shell material to determine the temperature of growth was first done in France using oxygen isotope ratios. Photos of the unpublished French-language report by Blamart and Bassinot dated 23 June, 2016 was later included in the Malaysian Safety Investigation Report as Appendix 2.6B released July 30, 2018. The shells of twenty flaperon specimens under 10mm were ground and analyzed for an isotope ratio which was referenced to the local sea surface salinity and temperature (mean 26.2 C) at Reunion before discovery. Three larger specimens measured 16, 19, and 25 mm across the scutum shell segment, which is about 82% of the overall capitulum length as seen above. These shells were analyzed using microabrasion by distance from the corner of the shell umbra where growth began. It was determined that growth began in waters at a higher temperature of about 28C, proceeded to lower temps around 25C, then slowly rose again to 26-27C before discovery. The authors referenced the Poupin estimate of the rate of growth for smaller shells up to two weeks and declined to revise it for larger shells, but concluded that growth during drift likely occurred in under a few months with warmer waters E-NE from Reunion.

The three largest of the studied shells (samples A2-G1,G2, and G3) were then sent to Australia for growth temperature analysis by ANU professor Patrick De Deckker using calcium/magnesium ratios. He also analyzed two smaller barnacles from an MH370 internal cabin bulkhead found at Rodriguez Island (NE of Reunion) on Mar 31, 2016. The Australian study was revealed in 2016 press interviews, and the report later published in October 2017 as appendix F of the ATSB Final Investigation Report. Dr De Deckker references several reports on growth rates, documenting that barnacles on a buoy immersed in 25-28C waters for only 17 days can reach a shell size of 23mm. He summarized, “Finally, we still do not know the timing of barnacle adherence to the debris, or the respective ages of the barnacle.” The analyzed temperature/growth charts from Reunion and Rodriguez barnacles did not match because they were found just months short of a year apart. The shape of the flaperon barnacles temp/growth curve was a good match for the Blamart-Bassinot study, but showed slightly lower values starting at 24-25C, dipping quickly to 20C, reaching 17-18C mid-growth, then rising to 25-26C with a brief drop to 20C just before discovery. The overall temperature curve results do not not differ by more than 1-2 degrees between the two studies.

It should be noted that although barnacles only swim and attach within the reproductive temperature range of 18-25C, once anchored they can continue to thrive at warmer temperatures up to 34C. Their fastest growth temperature may be at around 25C.

More recent growth studies

In 2019, Nasser M Al-Qattan with the University of South Florida published his doctoral thesis dissertation titled, “Stable Isotope Geochemistry of Shelled Marine Invertebrates”. He grew lepas anatifera in a laboratory environment at various regulated temperatures and analyzed the associated oxygen 18 isotope ratios in their shells. He found a linear relationship across the range of 14-26C. His third and final chapter focused on, “The Search for Flight MH370: Using Stalked Barnacles as Geochemical Tracking Devices in the Open Ocean”. In three separate aquaria at different temperatures, 45 barnacles were grown for 21 days with fluorescent timing markers, then analyzed. He compared O₁₈ ratios to the Blamart-Bassinot flaperon data, and determined the temperatures to be 2-3C cooler, noting “a difference likely due to methodological approaches“. (The French study was calibrated against barnacle specimens from Australian museums, and volatile measurements at the outer part of the shell were pegged to an estimate of the surface water temperatures at Reunion.) The new data is closer to the De Deckker range, but variations include that the Gooseneck species studied was shipped live from Ireland. They may not be an exact match for the lepas striata that was previously analyzed, with brown molting spots that had a higher mineral ratio when sampled.

The Al-Qattan study included a comparison of drift based on the HYCOM model which includes live data for surface currents and winds, with air and water temperatures. He calculated barnacle age of the largest studied barnacle AG-G2 (28.4mm shell) based on the Poupin logarithmic growth formula at 154 days. From that, he estimated from sea surface temperatures along the assumed route that sample AG-G2 attached the flaperon in waters at a temperature of 27C about 2,000 km east of Reunion. He concludes, “Larger barnacles that were collected from the same wreckage could provide important information to constrain the latitude of the crash site better.”

In August 2023, Al-Qattan was the lead author on a followup paper with other team members and his professor Gregory Herbert who is credited in many media reports as leading the investigation into using barnacles to narrow the MH370 crash latitude. The report gives more detail on the methodology of the earlier growth temperature study, comparing to a subsequent MH370 barnacle temperature study (Mesaglio et al, 2021). It highlights drift analysis using 50,000 particles with a new interpolation technique of which only one beached at Reunion Island, and notes on that drifter, “Its recorded drift reveals that the MH370 flaperon likely spent its last several months west of longitude 70°E and within 1,500 km of Réunion Island”. The drift study was again based on the Poupin growth rate formula, which the author acknowledge as critical area for future work, noting: “Error is introduced here if actual growth rates of individual MH370 barnacles varied from Poupin’s (2015) average, smoothed growth curve, as pointed out by others (De Deckker, 2017).”

A 2020 report by Mesaglio, et al studies temperature and growth rate of lepas anatifera. It explicitly states the MH370 flaperon barnacle species as lepas indica, often misidentified as lepas anatifera (striata). Comparing their experimental oxygen isotope data to recorded temperatures, they found the estimate using the Blamart and Bassinot formula was on average 2.68 degrees C higher. They point out from various studies that the growth rate can exceed 1 mm/day, and their experiment saw 1.45 mm/day growth in a favorable environment.

One analysis of growth on other found MH370 debris comes from the Oct 2017 ATSB final report of The Operational Search for MH370, Appendix G.3, “Review of Macrofauna on Pieces from Mozambique”. Only flora and snails were found attached, and they are generally found in coastal waters. The report summarizes:

• From the species assemblage recovered and identified, there is no evidence of any cool- or cold-temperate mollusc or annelid in these samples that might suggest the aircraft pieces had been in the cold waters of the Southern Indian Ocean.
• One third of the identified molluscs on Item 3 are sufficiently opportunistic to grow on floating debris, and represent juveniles at approximately two months old.

Page 107 of the same ATSB final report summary expressed the prospect that, “the chemical composition of the barnacle shells may yield some information about the temperature and salinity of the water where the various stages of the barnacle growth took place. For the oldest (and largest) barnacles it was thought that this may yield some evidence as to where MH370 may be located.” Unfortunately, they then state that, “The results of the analysis were inconclusive”.

Checking Prior Assumptions about Barnacle Growth Rate

Given that the Poupin logarithmic formula for gooseneck barnacle growth underpins other research, we can validate it against recorded size data. The inverse of that formula, mm = 6.7041 ln(days) – 5.333 is: days = exp((mm+5.333)/6.7041). A 2008 Dutch report on Very Large Goose-Barnacles, Lepas Anatifera L, notes the discovery of a small wooden box with 30 damaged barnacles, all over 50 mm in size. Three large intact samples preserved for a museum had capitula lengths of 52, 64, and 72 mm. The Poupin log growth formula predicts that these individual barnacles would be 14, 84, and 280 years old, which is absurd since they colonized together in a much shorter timeframe, and have relatively brief lives.

To gauge real growth rate, we can refer to a fascinating 1979 study of foreign barnacles transported to New Zealand on an oil platform. The platform was constructed in Osaka, Japan, launched, and towed on its side for 68 days to New Zealand with a two day fuel stop near the equator. It was assessed two days after arrival with over 1,000 kg (a ton) of barnacle growth. Spending time in open water, the biofouling was mostly barnacles. Twelve barnacle species were found – eight acorn (balanus) species and two stalked (lepas). The acorn barnacles were all juveniles that grew in the coastal waters of Japan. The stalked barnacles later attached in the open ocean and thrived, often atop the acorn barnacles. All species were alive at the destination, so little sign of predation or atrophy from the temperature changes.

Most common was lepas ansifera which tended to dominate in the deeper portions of the colonies, and lepas anatifera with a black stalk and regularly spaced rectangular spots (like lepas indica and striata). The typical size range of lepas anatifera was 6-28 mm (very similar to the flaperon), with the largest recorded sample reaching 52 mm. Per the Poupin formula, that would be 5,176 days, or over 14 years old. Based on an expected growth rate from previous studies of 0.7 mm/day, the researchers estimated that the barnacles attached near the tropical portion of the voyage (less than 30 days), but the upper limit is 70 days for any attachment in Osaka. This match gives an approximate dating range on the flaperon of 1-2 months.

New Flaperon and Barnacle Observations

From surveying various photos of the flaperon, it appears that some of the barnacles detached between its discovery at Reunion and arrival in Toulouse. The larger barnacles are in protected crevices. The largest barnacle seen is in a broken upper flange of the inboard flaperon hinge, with a capitulum length of about 39 mm. Barnacle sizes were determined by photogrammetry, using pixel measurements vs known reference dimensions in the image. Most online media photos are low resolution for fast web viewing, or frame captures from video footage at around 1/3 of a megapixel, but some full resolution images have been published and a few key ones are included here for fair use with credits where known.

Measurement of this barnacle required determining the inboard thickness of the flaperon. The DGA report figure 19 included some measured dimensions as very helpful references.

However, the flaperon thickness tapers along the length from the inboard end to the larger outboard thickness of 304 mm. This can be seen in a clear edge-on AP photo by Lucas Marie, of the Flaperon being examined by police at Reunion. Due to perspective, the pixel scale is slightly different closer to the camera at the trailing edge plane (1.3583 pixel/mm) than at the thickest plane (1.2946 pixels/mm). The photo verifies the above proportions from the report, and gives a 226 mm reference thickness at the inboard end for sizing barnacles (and incidentally the inspector) in that depth plane. The unique perspective in this shot also reveals that the flaperon is twisted several cm with the trailing outboard edge higher than the leading edge. This could be due to ocean impact. A slight upward arch of about 1 cm is also detected along the top of the flaperon. This can be seen in smaller DGA report images. It seems unlikely that an undamaged flaperon has these distortions.

Further measurement of trailing edge barnacles, though pixellated, shows the five longest ones range from about 26 to 32 mm. Many more barnacles look foreshortened from pointing toward the camera, but their width can be measured. Extrapolating capitulum length by averaged ratio from width suggests that the largest seen trailing edge barnacle may be about 35 mm (as sampled by Dr Poupin). The first image above showing a closeup of barnacles on the trailing edge can also now be measured. It takes in a linear 185 mm along the trailing edge, which equates to 16.3 pixel/mm in perspective scale. The capitulum of largest barnacle at the center of the image is about 32mm in length.

An extraordinary photo of the inboard leading edge of the flaperon shows intricate details of the barnacle growth. The hinge that contained the largest 39 mm barnacle is in a recess on that corner. Photogrammetric measurement of the largest visible barnacle in the center of the scene puts it at 36 mm. Beyond the measurements, other details in this photo tell us some chronology of the growth.

Evidence of prior beaching on the flaperon

Close observation of the leading edge around the hinge shows that the composite material and the screws holding it in place have been abraded away by contact (likely with beach sand, coral, or pebbles). The foam/nylon seal is also worn away on all corners from repeated contact after grounding. The innermost leading edge is visibly flattened. It appears that the flaperon spent some time being tossed around nose downward in shallow water with a sandy bottom. Most remarkable is that the barnacles have visibly attached and are growing on top of the abrasion damage.

Given that the larger barnacles are in protected recesses, and mostly juveniles are seen on the outer surfaces and atop the abrasion damage, this is a definitive indication that barnacle growth began after the flaperon made first landfall. This timing is consistent with news reports on the flaperon discovery with testimony from multiple witnesses that had seen it ashore in early May.

Winter growth temperature in Reunion waters

For validation that growth began after beaching, the previously analyzed temperatures during growth should match with the temperatures near Reunion Island during that time. Sea Surface Temperature (SST) is mapped daily by multiple weather satellites in low Earth orbit. These measurements are included in various ocean survey databases such as the HYCOM.org model. For comparison in this report, data was collected in a 1×1 degree region off the NE shore of Reunion, at a 5 km resolution giving 21×21 = 441 averaged daily samples. The sampling period was from May 1 to July 29, 2015. (In retrospect, a broader time range might be informative.) The water temperatures were near the annual minimum of the Austral winter at Reunion.

The Blamart/Bassinot temperature growth graph is chosen because growth size progresses similar to the time plot. The De Deckker and Al-Qattan growth temp studies have similar temperature variance and shapes to the charts, but different offsets. The French study pinned the final temperature to an estimated average temperature for Reunion Island prior to discovery, while the Al Qattan estimate is a closer match to the slightly cooler temperature in the SST chart above. It can be seen that there is a convincing correlation between these two temperature charts.

Discussion

Past attempts at matching debris drift to barnacles had assumed that the crash site was in colder water, that barnacles grew more slowly as they aged, and that growth should have begun either near the crash site or somewhere en route toward Reunion Island. None were able to account for a faster than expected arrival, or for growth beginning at the warm end of the reproductive range. The proposed tropical crash site off the coast of Java based on acoustic detections is instead consistent with the barnacle and drift evidence. The only three pieces of debris found with barnacles were either found in winter months near Reunion, or at the far southern tip of South Africa in colder waters. All the other pieces found with algae and snails apparently never left tropical waters too warm for barnacle reproduction.

The ATSB worked closely with Dr David Griffin of CSIRO as their expert on drift modeling. In a CSIRO press release, Dr Griffin notes early concerns that the flaperon had arrived earlier than expected by drift modeling of mock debris, which also had debris going north of Reunion. His later drift experiments using a real flaperon from Boeing showed higher windage and a leftward track, which he says brought a revelation that the flaperon could have reached Reunion on time from the active search area. Debris from the Java candidate crash site would have drifted offshore and west, directly into the westward Southern Equatorial Current. Barnacle growth after beaching changes the estimated arrival time. Rapid crossing of the Indian Ocean also explains how the second item “Roy” traveled the farthest to the southern tip of Africa, carried there by prevailing ocean currents with few detours.

Other drift studies have used the CSIRO drift model data in attempts to narrow the crash origin. They applied constraints that the flaperon and other debris must have been discovered shortly after expected arrival. This finding that barnacles grew after beaching challenges the basis for their conclusions, confirming that various debris was likely found many months after expected landfall.

One of the earliest reports on drift modeling after the flaperon was found came from Geomar researchers in Sept 2015 using a previously established reverse drift model. They did not constrain origins to the 7th Arc. Looking at their probability map, the highest density along the 7th Arc occurs at the Java candidate site. Several later studies using critical windage and Stokes drift parameters tailored specifically to MH370 debris may have inadvertently skewed results toward the expected consensus search area.

A 2018 drift study by Oleksandr Nesterov addresses the barnacle growth temperatures, and randomizes drift parameters to avoid bias. Oleksandr developed supplementary drift animations from starting points along the 7th arc, and kindly tailored one specifically to the Java candidate site. It predicts debris drifting directly toward all the locations where debris was found, arriving earlier than from other candidates.

The finding of barnacle growth starting after landfall has direct implications on the rate of their growth. The slower the barnacles actually grew, the longer they must have arrived before the flaperon discovery. Advocates for 7th Arc crash sites south of 21S latitude are now faced with much quicker barnacle growth to allow time for late beaching then growth before discovery.

It is not impossible that flaperon beaching could have occurred before reaching the Mascarenes. The earliest opportunity for any grounding would have been at Christmas or more likely Cocos Keelings Islands, but that is far off track of any modeled drift from the areas already searched. Debris drifting that close to Indonesia only becomes likely from a tropical 7th Arc crash site.

More details might be gleaned from photographic evidence. The width/height ratio and shape of barnacle shell edges may be related to changes in their rate of growth over time. Swirling patterns on the ends of the flaperon indicate where algae was brushed off by the the waving cirri of the barnacles. Cleaner algae shadows show where some larger barnacles once swept a larger radius but are now missing. Even higher resolution closeups might reveal additional metrics and insights, if only they could be shared in a public archive.

Since the suspension of search efforts in 2018, Malaysian officials have set a threshold for resumption requiring “credible new evidence for a specific location”, plus a condition of “no find, no fee” from search contractors. On this 10th anniversary, officials want “compelling new evidence” to resume the search. The Java candidate site is very specific, defined by the epicenter directly on the 7th Arc of an acoustic event heard by 40 regional seismometers and over a dozen ocean hydrophones. The event timing and signature are consistent with the seabed impact of a large sinking section of MH370. The site is so specific that any team with a submersible capable of bathymetry at 3,400m depth might survey the site in a single dive. The site coordinates can be validated from public seismic data, and the location is surprisingly consistent with all of the factual evidence available about MH370.