URL originale : https://books.openedition.org/editionsmsh/57916

Chapter 12 – Debate with experts and general discussion
p. 275-299
Texte intégral
1Moderator : Robert J. Koestler
2Experts : Hideo Arai, Antoine Danchin, Thierry Heulin, Philippe Normand, Alena Nováková, Pascal Simonet
3[ The interventions in italic were translated from French to English.]
4Mr. Robert J. Koestler
5We need to begin; if you could take their places please. I had around 400 questions that I am sure you all thought of as well, but I would like to start by focusing the discussion at least a little. We may drift considerably, but it is important to begin, at least, with a specific issue: do we know enough to return the cave to its previous stable environment and should we? Then, my other personal thought concerns the use of enclosed UVC lamps to control the air‑born spores and fungi in the atmosphere in order to give us time to react. There are other intermediate subjects, but I think that we can start with this first one; some may feel prejudiced, but we must begin somewhere. If our panel participants could briefly introduce themselves, we can then begin with our questions.
6Mr. Antoine Danchin
7I am the Director of the Genomes and Genetics Department of the Institut Pasteur, and I am therefore here as a representative for the domain of microbiology.
8Mr. Thierry Heulin
9I am a Directeur de Recherche at the French Centre National de la Recherche Scientifique (CNRS), and I am the Director of an institute in Cadarache that takes an interest in plants and bacteria. I was fortunate enough to visit Lascaux a few years ago, in 2002, when the white fungus growth was at its peak. I am also a soil bacteriologist and microbial ecologist.
10Mr. Philippe Normand
11I have been the Director of a microbial ecology laboratory, and I am currently working on soil bacteria using physiological, genomic and general ecological methods. I am particularly interested in the actinobacteria found in soil and rocks.
12Mr. Pascal Simonet
13I am a Directeur de Recherche at the French Centre National de la Recherche Scientifique (CNRS) and a soil microbiologist, particularly in genomics and metagenomics. I am currently actively involved in a large project that consists of sequencing all the bacterial genomes of a soil type using such metagenomic methods.
14Ms. Alena Nováková
15I am mycologist and I would like to respond to all the presentations made up until now. In my opinion microscopic fungi are an integral part of the global system of the cave and they can grow in this oligotrophic environment in function of certain specific properties. As sapotrophic organisms, they of course need this organic material, which in the cave has a vegetal and microbial origin, but in an oligotrophic environment, they can draw a small amount of organic material from the water or from the biofilm covering the cables, for example. Fungus spores contain a minimal amount of nutrients that are essential for spore germination and for initiating mycelial growth. In addition, fungi grow in a larger part of the mycelium and can suddenly decompose all parts of mycelium and transport this compound over a larger space. This is how we can see a fungal mycelium, for example, in bio substrates such as the cave remains or vermiculations on cave walls. We have heard other opinions on the current situation inside Lascaux Cave, but only one presentation addressed the outside environment.
16Mr. Robert J. Koestler
17Can we hold on a second? I really just wanted your name. We will give you chance to talk again later. The first question I raised was: is our knowledge sufficient to return the cave to its stable environment and should we? Would anyone like to respond?
18Mr. Antoine Danchin
19As far as the microbes are concerned, I feel that it is extremely important to understand that it is difficult even to define a microbial species, for a very particular reason. In fact, even though they do have a common set of genes that more or less define the species, they share a very large number of other genes with the whole community in which they live, distributing them among different strains.
20I therefore think that, to start with, it is completely illusory to think that we could make a U‑turn. We are in a situation that must be analyzed on the basis of history. It is very important to understand what we have contributed to these microbial communities, and perhaps to associate genes to the consequences of our intrusion in the cave. In reality, we are in a situation that bears some resemblance to that of chemotherapy used to treat cancer. This therapy is successful only if it kills all the cancer cells. Yet, it is currently totally impossible to kill all the microorganisms in the Lascaux Cave.
21We must therefore aim rather at finding a new balance instead, one that adheres to the specific rules that must be applied— to the human impact in the cave — in particular, the significant constraints in terms of access, general monitoring of the cave and its atmosphere, etc.‑‑ and not think that we can return to the previous microbial community. We have visibly contributed a great number of elements that have allowed the development of new communities. We have especially talked about carbon and nitrogen, but it is very likely that there are also metals that completely change the electron transfer in cells and thus the microbial populations.
22It seems to me that we are in a situation where things are evolving very rapidly. We must therefore attempt to understand what is happening, but if we start to add further new elements, I fear that we will only make the situation worse.
23Mr. Pascal Simonet
24This morning, Claude Alabouvette showed how the development of techniques allowed increased precision in defining bacteria or fungi. We have seen that when we try to cultivate them we achieve some diversity, which becomes much greater when other methods are used. I would like to make it clear that these other methods also have their difficulties, their biases and their lack of sensitivity. We now know that we can use these methods to find a certain number of bacteria to represent the most prevalent types. We know that all ecosystems contain an extremely significant number of bacterial populations that are represented by a very small number of individuals. The tables that have been shown probably under‑represent the actual diversity, especially for bacteria that might be pathogenic to people. It is therefore far from certain that these bacteria have been introduced through visits. They could be present completely naturally, as can be the case with other bacteria. I also feel that even the anthropic origin of some of these microorganisms can be questioned, without excluding this possibility.
25Mr. Thierry Heulin
26First of all, I would like to highlight the quality of the work that has been done and to emphasize the contribution of molecular biology tools in the attempt to more effectively describe the evolution of the populations present.
27I just wonder about the strategy. It is completely illusory to imagine that a treatment could eradicate what seems unbearable to us on the paintings—especially mycelium—because any treatment will target not only what is visibly annoying, but will also probably eradicate everything that is not targeted, in other words, all the bacterial populations that are there and which, before the cave was opened, allowed a stable condition, a balance between hundreds, if not thousands of species that had a relative control, to the point that there was no population explosion of one species relative to the others.
28Every time we treat a target, we also affect the non‑target, as is the case when we take antibiotics. We are in exactly the same situation here. We must never lose sight of the fact that all treatments, including mechanical ones, remove the biofilm and sub‑strain of microorganisms present, which must be maintained at all costs.
29Nevertheless, we all agree that we do not have a solution. In 2002, I proposed the slightly crazy idea making an inventory in the Shaft of the Dead Man—which Claude must have partly done—and remove the populations that had never undergone treatment in order to see if it was possible to reintroduce them into a model system and manipulate them. I feel that some microbial ecology experiments need to be done using the native populations, to try and observe through experimentation whether introducing these populations—there have to be several species—would create a barrier effect to avoid the population explosion that we feel is visually unacceptable.
30Mr. Robert J. Koestler
31Whenever one of the speakers wants to add something, please don’t hesitate, so that we can get a dialogue going…
32Mr. Philippe Normand
33I would also like to highlight the quality of the work, even though I have never been to Lascaux and I do not know much about the situation. I do know about microbial ecology, however. One of the things that has surprised me in the work presented is that the catalogues of microbial strains found do not include anything at all on what is found in a typical soil.
34A typical soil would include dozens and dozens of taxa that grow extremely slowly, particularly actinobacteria that are also present in other caves, in Spain, for example. One of the properties of actinobacteria is that they produce antibiotics. It is therefore a matter of balance between populations, between large taxa, which seem to have changed completely here. The bacteria that are found grow very quickly, and this is the case with Escherichia coli, which is a fecal indicator. I would like to understand where it comes from. Maybe it comes from the soil above or from human contamination. There is not only Escherichia coli, moreover. Legionella, Burkholderia and Ralstonia are other bacteria that develop very quickly and are usually found in rocks or soils.
35Ms. Geneviève Orial
36I would like to make it clear that Escherichia coli has not been found in the cave. It was the strain that Claude Alabouvette worked on for the sequencing. There is no Escherichia coli at Lascaux.
37Ms. Fabiola Bastian
38I work with Claude Alabouvette. Escherichia coli was found using molecular biology. It is true that it has not been isolated, but it has been detected all the same. Claude has shown that it was not the most prevalent, but a small quantity of Escherichia coli has been found nonetheless.
39Mr. Antoine Danchin
40We have basically been talking about organisms that can be isolated on Petri dishes. Yet, the vast majority of organisms cannot be isolated, basically because they can only grow in combination with others. This is also a rather important point. What we find using non‑molecular morphological techniques most often corresponds to a small minority of the whole community.
41There are many contexts other than the Lascaux Cave where there is a situation of this kind. When we try to improve things — adopting the European cheese regulations, for example— we very quickly introduce the risk of allowing the development of a pathogenic bacterium, for example, that would otherwise have been blocked by a barrier consisting of the large community of bacteria that very often cannot be cultivated and live together with the cultivable species.
42Mr. Pascal Simonet
43We have spoken about the balance that could have existed before the cave was opened. Once again, this idea has perhaps been exaggerated a bit because bacterial genomes and interrelationships between microorganisms change continuously. Since these paintings were realized, there have probably been a large number of general modifications in the microbial communities, both bacterial and fungal, with no deterioration of the paintings as a result.
44At the microbial level, there are continuous changes. We must abandon the idea that humans entered into a cave that was completely static and that from then on everything was upset. Changes and modifications had already occurred. Maybe there are other caves where the paintings have been destroyed, and we will never know about them because their physic‑chemical and biological conditions were negative.
45Mr. Robert J. Koestler
46The presence of an organism does not mean the activity of organism. We can isolate them with our tools; our tools are wonderful for studying, identifying and finding things, but we always run into the problem of what are they doing and are they really doing anything. We can try to get around that by looking at RNA, or looking at other parameters that we can measure to find out if they are producing something, but again, it does not actually say that they are producing something that is a problem. The only way we know is visually; we know that we have fungi that are producing something producing a black stain which will not go away by itself. So we see a real problem at that point and we feel we have to do something.
47Mr. Claude Alabouvette
48The results are not yet available, but I know that Cesáreo Sáiz‑Jiménez is doing this type of work; comparing for the bacterial population what is coming from the DNA and what is coming from the RNA. This allows us to distinguish between the total population and the actively metabolically growing active population. We now have a project to do the same with the fungi, but this is technically more difficult to achieve.
49Mr. Robert J. Koestler
50Please, go ahead.
51Mr. Thierry Heulin
52We must indeed bear in mind that most microorganisms cannot be cultivated, either in this cave or anywhere else. To return to my suggestion of testing a barrier effect through experimentation, the idea is not to do classic microbiology, as we do when we isolate and cultivate a strain. I am rather referring to a somewhat complex microbiology, which involves cultivating—including minor fermenters—from all the populations, which has the advantage of not separating the bacteria and the fungi. It seems to me that the associations in this case are very strong and very interesting, to attempt to see, experimentally, whether this type of complex inoculum could be tested for its capacity to act as a barrier against the fungi that we know are very active, whose proliferation we could prevent experimentally.
53Mr. Philippe Normand
54Mr. Simon from Berlin said yesterday that we know everything about Lascaux. I do not entirely agree with him. In particular, we have learned that organic material circulates in the solution. This question of organic matter is key because a bacterium—and this is the first thing that we learn in microbial ecology—uses carbon and nitrogen. What is used by the strains that develop in the biofilm? I do not think that we have had any clear answers on this point. This is the domain of bacterial physiology, and I think this is something we need.
55Mr. Robert J. Koestler
56Dr. Arai, would you like to make a few comments?
57Mr. Hideo Arai
58First, I am grateful to the committee for inviting me to the 2009 Lascaux Symposium. In my opinion, microorganisms that develop on elements of cultural heritage should be eradicated as soon as possible because we must protect this heritage from deterioration. To control microorganisms, there are several methods: fumigation, application of biocides, water and environment controls.
After I received an e‑mail from Ms. Geneviève Orial from the Laboratoire de Recherche des Monuments Historiques about the 2009 Lascaux Symposium, I confirmed the efficacy of several sterilization methods that could be used against the fungi that have developed in Lascaux Cave.
1. Fumigation. We are applying in the field of cultural heritage in Japan, an ArP fumigation system using propylene oxide diluted argon. I have treated three strains (Fusarium solani, Ulocladium botrytis and Ulocladium consertiale) by this method. As a result, they were sterilized perfectly. However, since Lascaux Cave cannot be kept airtight, I think this method is not possible.
2. Biocide spraying. I tried the method of spraying a 2.0% mixture solution of 5‑chloro-2‑methyl-4‑isothiazoline-3‑one and 2‑methyl-4‑isothiazoline‑3‑one (trade mark: Hokucide R‑150). As a result, the three strains mentioned earlier were sterilized. This biocide is applied to protect the surface of decorative paintings on architectural works in Japan. Fungal growth was inhibited for 3‑4 years after treatment. I have heard that this biocide was already introduced to the LRMH.
3. Effects of fumigant and biocide on pigments. It is said that the rock art in Lascaux Cave was realized with three kinds of pigments (manganese oxide, hematite and magnetite).We prepared test pieces of these pigments on thick paper and treated them with ArP fumigant and biocide. When I confirmed the change of color, I could not find any adverse influence on these pigments of test pieces.
4. Water control. We know that water is essential for the growth of microorganisms. When it was found that the blackening of plaster walls in castles and other structures in Japan were caused by the growth of fungi (Cladosporium spp.), we treated the plaster walls with an inorganic and ventilating watertight chemical (trade mark: Rekkanon). We have not found fungal growth on these walls for seventeen years or more.
59I consider this to be very effective to protect the growth of fungi.
605. Control of the subterranean environment. According to archaeologists, fungal growth cannot be found in unexcavated subterranean environments. We carried out an investigation in order to learn about the subterranean environment in an unexcavated tomb at the Torazuka Tumulus in Japan. Although I reported amines as an antifungal factor as a result of this investigation, we have not been able to continue the research at other sites.
61However, if we can clarify the factors that contribute to maintaining a stable subterranean environment, it may be possible to propose to the world an effective conservation method. For this, it is necessary to conduct joint research with people from many fields.
62Mr. Robert J. Koestler
63Thank you. We must take note of this information and transmit it to the Committee so that new suggestions can emerge and be considered. Alena, I cut you off earlier, do you want to add something to what you said?
64Ms. Alena Nováková
65I can say that in our country, we had problems with micro‑fungal invasions, not on paintings but on aragonite speleothems, in the Zbrašov aragonite caves. This situation of micro‑fungal growth appeared after these speleothems had been disturbed; this situation was resolved by spraying a 10 %, hydrogen peroxide and fungicidal solution.
66Mr. Robert J. Koestler
67Okay, thank you.
68Mr. Pascal Simonet
69I would like to talk about what Claude Alabouvette presented. He indicated that the bacterial diversity in the treated zones, at least that of microorganisms, was greater than in the untreated areas, and that Lascaux also has a higher proportion of proteobacteria than elsewhere. This touches upon the whole difficulty of microbial ecology and is linked to the first question you raised: Can we reestablish the former condition? By wanting to eliminate, we create practically the opposite effect. We introduce more diversity. This diversity may be good or bad, but either way we see an increase. It might be interesting to go to the unexplored areas and see whether or not the same proportions are present there.
70It is extremely strong evidence of human intervention, of what humans have been able to do, by means of the proposed treatments, to change the ecosystem, at least in part.
71Mr. Thierry Heulin
72I have just one question for Claude Alabouvette. When you present the treated and untreated zones—I would like to be sure that I have understood this correctly—there are some areas that have experienced problems and that have been treated in a localized manner, using products or other means. With regard to what I consider to be the unvisited area, you sampled the beginning of it but you did not go to the end of it. Is that right?
73Mr. Claude Alabouvette
74We went to the end of the sanded gallery. The diversity there is extremely limited. Here, we clearly took a shortcut that is not entirely valid since we sampled the zones that were visibly colonized and the areas that were visibly not colonized, and the Shannon Index works when we compare colonized and non‑colonized zones. Nevertheless, the colonized areas were evidently treated, since they were the target of the treatments.
75Mr. Antoine Danchin
76You have not mentioned bacteriophage viruses at all. However, in the general environment we find billions of viruses all over the place, and this where the exchange of genes most effectively takes place. Furthermore, this could also be a possibility for control that would be interesting to try. Have you explored this?
77Mr. Claude Alabouvette
78No, we have definitely not observed the viruses.
79Mr. Robert J. Koestler
80Let me push it a little bit. We have a problem of organisms growing now and we know that there is a problem. We have the theoretical problems that we are now talking about: the ecology, the organisms. We are worried about organisms that may or may not have consequences. We are faced with an issue of solani that has already had effects and now seems to be under control, I think through biocide treatments. We do not know whether there will be any repercussions of that. Time will tell. We now have a proliferation of melanizing fungi, regardless of what we choose to call them, but we have a problem with the systematic manner in which we name things because we do not know what really makes the difference in some cases. We have black staining fungi with different names, some producing melanin. The melanin is roughly the same with some slight differences. Some treatments would get rid of all types of these. This one might be more specific. What are we going to do about those? Are we doing enough? Do we know what it is to control the environment? We know that as the humidity in the environment increases and decreases, it puts a stress on black staining fungi and it might be producing the melanin because of that. Is there any kind of consensus or agreement on this subject?
81Mr. Claude Alabouvette
82I spoke a lot yesterday and today with Philippe Malaurent concerning the carbon and nitrogen nutrient problems. You have commented that metallic salts in particular could great alter the microbial diversity, and yesterday all the discussion was about humidity.
83We must understand that microorganisms are sensitive to water activity, and not to relative humidity. Osmotic pressure must also be taken into account. Someone commented yesterday, after the presentation by Roland Lastennet, that there could have been very limited flows. These flows must not be viewed simply in terms of free water, but in terms of charged water. Moreover, one could well imagine that, depending on the nature and concentration of the salts present in this water, there would also be osmotic pressure problems, meaning that the fungi would not be able to develop there but might be able to develop elsewhere.
84Here, we are achieving the scale of the area colonized by microbes. I feel that it is something very important that needs to be taken into account.
85Ms. Isabelle Pallot‑Frossard
86I would like to make a general comment. Since I am not a microbiologist, I will not go into these very technical discussions, but would like to correct the impression that the sequence of our two presentations this morning may have given.
87One of them presented the history of what has happened in the cave, with a period that was necessarily very intrusive because the fungi were there too, and all the tests that we are doing relative to the various forms of treatment. You have been given our most recent results, which indicate the possibilities for chemical treatments. The other presented a research method that aims to understand the microbial ecology of the cave, and it may seem that the two approaches are completely opposed. In fact, they are not opposed. I would like us to refocus the debate on what we are actually concerned about. There is not, one on side, people doing research in order to better understand the microbial ecology of the cave, and on the other, people working to cope with the most urgent issues, applying rapid treatments without always measuring the consequences of their actions. This is nonetheless the impression that one could have. I would like it to be very clear that there is no such dichotomy.
88We all agree that the ideal would be to find a biological balance, the one that there was before the fungal explosion in 2001. We are all hoping for that, but we do not know at what stage this balance will return. In 2004, when there was less pressure from Fusarium solani, we were the first to want to stop the chemical treatment, and to remove the fungi physically—though we are now told that they must not be physically cleaned either.
89There comes a time when can no longer allow ourselves to leave a pool of permanent contaminants that are continuously likely to re‑sow their seeds in neighboring areas. We thus had to act. We understood that we needed to proceed in the least intrusive manner possible, and of course to find a balance. Nobody wants to eradicate anything, and this is why all the drastic solutions that could be imagined (fumigation, or radical treatments using ionizing radiation) were ruled out from the beginning, with the knowledge that we should not create a biological void under any circumstances. This would have been completely illusory; another species would have taken the place of those eliminated and we do not know which one. So we know we must live with fungi.
90We also have the huge responsibility of maintaining the fragile paintings, engravings and substrata. We have shown the possible negative effects of biocides, but we must know that microorganisms also have a negative impact on carbonated substrata, for example. Microorganisms that produce organic acids can trigger partial dissolution of carbonated substrata. They produce melanin, which causes stains. They act mechanically by penetrating the substrata: we can see mycelium entering the rock pores and acting mechanically on these substrata. We therefore have to take this action by microorganisms into account, as part of our collective obligation to preserve the paintings.
91Here is the crucial question: can we act to reduce this biological pressure, so as not to allow the development of microorganisms that could themselves develop into a pool of contaminants, which would in turn develop? If so, how can it be done? Is there a negative physical impact? It has been shown that it cannot be done in fragile areas. Can chemical products be imported and, if so, which ones? Here again, it must be demonstrated whether or not the products we have are possible nutrients for future microorganisms. The studies that we have done with Thomas Warscheid show that they are not, but Claude Alabouvette tells us the contrary. So let’s talk about it, openly and freely.
92The idea is not to create a biological void or carry out a drastic treatment, but to slightly reduce the biological pressure in order to preserve these paintings as well as possible and for as long as possible. Of course, research is completely fundamental, and this is why we chose some years ago to work closely with Claude Alabouvette, as well as Thierry Heulin.
93It is clear that we must become better acquainted with the cave’s biotope, using all modern techniques. We are learning a little more every day, in the medium term and not in the short term. Current research will not provide us with a solution for tomorrow. If the fungi develop more significantly tomorrow, we will not have the solution. We must thus not prevent ourselves from finding a medium term solution by acting irresponsibly today, but we must nonetheless find the key that will allow us to treat immediate problems.
94Mr. Thierry Heulin
95For my part, I would not say that we have to “reduce the biological pressure”. We have to reduce the target, the one that is annoying in this context, because the same microorganism could be very useful in another context. In this situation, we must try to aim specifically at this target. The biological pressure must be there, but with a balance other than the one that is currently there.
96All the same, I am quite sure that any chemical treatment will release the carbonated or nitrogenated substrata that could potentially be used by undesirable organisms. This is a gut feeling, but it is also based on some experimental data. I would err on the side of thinking it is urgent to do nothing in this domain. This being so, I agree with you that something has to be proposed.
97In the short term, I do not have a solution to suggest, even if one perhaps exists. In any case, we must remember that the solution has to take into account the fact that we must not decrease the number of organisms that could potentially be there to limit a proliferation.
98In the medium and long term, I feel that Lascaux—especially if you have identified a cave in which some experiments could be conducted effectively—should be used as an example in cave microbial ecology, since there are resources available for this, and we must consider testing several hypotheses related to barrier effects, other physical treatments and other possibilities.
99Even though I cannot suggest a miracle solution for the very short term, I would like to discuss what could be done to experiment with original solutions that have not been foreseen up to now and which could seem a little iconoclastic, such as reintroducing bacteria to combat the bacteria. Nevertheless, this is done very generally.
100Ms. Isabelle Pallot‑Frossard
101I think some years ago we sent some strains for testing with a view to biological control.
102Mr. Antoine Danchin
103Have bacteria that inhibit the growth of the melanin‑producing fungi been found in the cave, for example? It is conceivable that this property could be analyzed systematically.
104Mr. Robert J. Koestler
105It is difficult. Some years ago we started working on melanized fungi to try to produce them and isolate them from later stages. We were then able to perform sequencing and to determine the cause of the problem that I presented to you; there was a Cladosporium and I asked someone to perform direct sequencing from the spores. We were eventually able to identify the problem and we knew the kind of melanin that was there. The next stage was to organize it and try to produce it. We developed a chemical solution, the copper operating system, which would be more generic and easier to apply than before, but it would be interesting the follow up because every melanin is supposed to have specific properties; this would thus be an interesting study to try even if no one has the resources here. I imagine that it would be useful to do it right away.
106Mr. Philippe Normand
107I have a question for Claude Alabouvette, who has worked on suppressive soils and Fusarium. It is therefore a matter of biological control, and I was surprised that he did not talk about this much in his paper, because it seems to me that this is a very interesting approach. Claude, what can you say about suppressors?
108Mr. Claude Alabouvette
109Once again, it is a matter of increasing, and not reducing, the diversity of the biomass. Resistant, or suppressive, soils are those in which the pathogenic fungus, in this case a Fusarium oxysporum, is present at inoculum densities that are essentially as high as in the soils in which the disease appears. In these soils, the disease does not appear because all the microbial communities act to stop the pathogenic expression and activity of the fungus present.
110The density of a pathogenic fungus—this was our first surprise—that does not demonstrate its activity is often greater than the density in a soil type where the disease appears.
111It is very complicated from a microbiological perspective, and we initially worked on competitions within the Fusarium oxysporum species because competition for nutrients is generally even more intense.
112Mr. Robert J. Koestler
113May I ask you a question?
114Mr. Claude Alabouvette
115Of course.
116Mr. Robert J. Koestler
117The application is going to increase biodiversity in the cave. Do you have to reduce the number of people entering the cave?
118Mr. Claude Alabouvette
119Yes, probably.
120Mr. Robert J. Koestler
121Because there is a direct relationship. So, is five people a day too many?
122Mr. Claude Alabouvette
123I don’t know, but I think the tendency would be to increase the diversity.
124Mr. Robert J. Koestler
125Is there a general consensus that we need to increase the diversity?
126Mr. Pascal Simonet
127Yes, I completely agree with what is being suggested. Some other initiatives can be taken. For example, we know that for some organisms, genes will be expressed, particularly those that can produce phenomena such as the ones we observe here, but only when a certain population level is reached, and this is called quorum sensing. As long as the bacteria do not reach this population level, almost nothing will happen. When this level is reached, the genes are activated and many things can happen.
128There are now means for combating this, either by biological control or directly using these molecules. Thierry spoke of an experimental site a little while ago. In spite of everything, the risk is still less significant than having something extremely drastic that reduces everything to zero, with the risk of another colonization later on.
129Mr. Robert J. Koestler
130A middle term or intermediate strategy seems to be appearing. It seems that if you want to increase the biodiversity the process is longer and you must reduce the number of people entering the cave. Five a day is too many. I don’t know what the acceptable number is, we don’t necessarily know, but it will really have to be reduced. This is what I understand. This could be an intermediate solution. It will not remove the black fungi, but it seems to me to be a necessary long term goal for the health of the cave, if increasing the biodiversity is something we are aiming for. But in terms of more direct and immediate action regarding the Cladosporium, or whatever we are going to call this black staining fungi, what should we do about it?
131Ms. Isabelle Pallot‑Frossard
132This is our responsibility and we must answer this question. If these black stains develop more quickly than they are now, what will we do?
133Mr. Philippe Normand
134What do they feed on? What is their source of carbon? I don’t think we can progress beyond this point if we do not know what they feed on.
135Ms. Geneviève Orial
136Yes we can. In this cave there is a very significant accumulation of dust, which could even be carrying a source of nutrients. There are also some contributions that are linked to the infiltration waters. There is vegetal cover above, and the infiltration waters are not neutral.
137Mr. Philippe Normand
138I addressed this point through the presence of Escherichia coli, which I think might come from the infiltrations. I wondered what was foreseen in terms of drainage and protection from what descends from above. If the bacteria and fungi feed on organic matter originating from the soil above and we seek to reduce these infiltrations, we could consider drainage, among other things.
139Ms. Geneviève Orial
140We do not know about this part, because there really has been a normal amount of accumulated dust since the opening. In the first few years, many people entered, resulting in the accumulation of film of particle pollutants that became incrusted and are clearly a source of nutrition. What I am saying is hypothetical. There is also quite probably a contribution from infiltration waters, but there is a definite contribution from this particle layer.
141Mr. Pascal Simonet
142Of course, but here too, this solution involves the risk of significantly modifying the ecosystem, with consequences that we do not know about.
143Mr. Philippe Normand
144Yes, but I am talking about removing a source of carbon there. The disruption to the microbial ecosystem is much less significant and shorter‑term than when benzalkonium is added, since it is permanent.
145Mr. Antoine Danchin
146It seems to me that we might begin not with a solution, but at least with a way of improving our knowledge: in the very short term, assuming that there is appropriate funding, by deciphering the genome of the organisms that produce melanin. This is a huge endeavour…
147Mr. Robert J. Koestler
148If there are nutrients in the cave, which we know have been brought in by humans in all sorts of things and in all kinds of caves, we should be able to clean them out, right? Can’t we install filtering systems to help filter the air to pull some of the material out and reduce the food load, so that it will have an effect on the diversity? But the nutrients have been there since the 1940s…
149Ms. Geneviève Orial
150Yes, but we currently have far fewer entrances to the cave. I am talking about previous deposits that have become attached to the walls. As we told you, the impact study shows that we cannot clean the molds. If we can’t clean the molds, it will also be difficult to clean the layers of particle pollutants, at least in the sensitive zones that have been affected by contamination.
151Ms. Isabelle Pallot‑Frossard
152We should also note that the zones in which the melanin fungi are developing are not the ones that have been the most heavily treated in the past. They are some on the ceilings, for example, which are areas where there has not been a great accumulation of treatments, since they are the most difficult areas to reach. All this remains to be studied and I don’t think we have addressed all the pertinent questions.
153Mr. Thierry Heulin
154In principle, it seems that a mechanical removal treatment that takes much longer and which, in my opinion, must be much more cumbersome to carry out, would be preferable to a chemical treatment, for the very simple reasons that it does not re‑supply the carbonated substrata. That being said, we still need to have the means.
155Ms. Geneviève Orial
156We have said the same thing.
157Mr. Robert J. Koestler
158Let us open the discussion to the floor! Thomas.
159Mr. Thomas Warscheid
160First of all I must admit that I am a bit lost in this discussion. We talked about the implications or the possible influences of biocide treatments on the microflora, but we also talked about the possibility of limiting nutrients and about filtration systems. These would have impacts that would even further aggravate the situation. I am not a big fan of biocide treatments. I disagreed with the biocide treatment at terracotta, I convinced people that this treatment was not appropriate there. Here I have seen that we are in a totally different situation. I am not a fan of biocide treatments. Everyone who has worked with me for a long time knows this. I agree that if we can solve the problem through climatic assistance and cleaning, it is better.
161I must also say that I am also an ecologist and I like to see variety of organisms and their interrelationships in one place. We should never think that microorganisms take care of our cultural heritage. They want to live there and don’t care about the rest. They want to live there and I know that a diverse microflora is more stable than a monoculture. We have known this for a long time and it is not new, but the situation we are in now is slightly different. We are not dealing with a monoculture and we have to be careful in saying bacteria are beneficial; after all, bacteria produce acids just like fungi. And they can be responsible for acid attacks. Selenomonas was mentioned; if this bacteria feeds on organic materials, what about karstic stone? What do we really know? I come back to my question from yesterday: what are the consequences revealed by our studies concerning melanin? Because this is the threat we have to deal with. There is much to say in the domain of ecology. If we can do research on this subject, I am delighted. Many people in this auditorium are not microbiologists and do not understand a whole lot of our discussion. They hear about molecular biology, which is in style these days. There is a real interest, but no one has asked whether we are really able to use these techniques to better understand the ecology. They give us more information but make things more complicated than before. I insist on this aspect because it is a very important for us to be able to realize these studies. We must be cautious and not get carried away.
162You have highlighted the possibility of using organisms to combat other organisms, and we know that is possible. Nonetheless, we should not become overconfident in these techniques because, even in medicine, the results obtained are not as successful as we had hoped they would be after twenty years of molecular studies. Let me try to illustrate my point in a way that might be somewhat provocative. When you have a patient with cancer that must be treated by chemotherapy, with its numerous disadvantages for the patient, do you recommend to him that he stop the therapy and let himself die of cancer?
163Mr. Robert J. Koestler
164Okay.
165Mr. Claude Alabouvette
166I have just one comment to make. It is commonplace to oppose molecular biology and traditional techniques. This is a very old debate that has no reason to exist. Everyone knows that we should use all techniques conjointly. There is no sense in opposing traditional techniques and new methods. I am not a molecular biologist, as you can guess from my age, but it is obvious that new technologies that allow us to take into account the entire community with rapid techniques should be used in Lascaux if you have the possibility. We can have hundred of samples together.
167Mr. Robert J. Koestler
168We must also remember that just because we have a new technique does not mean it is not going to solve every problem encountered. It can be useful, and is the aim is to find the right balance between the technique and the knowledge we have in order to find the appropriate response. We need to find a solution to the problem of the black fungi; how are we going to do this? We should not leave this table until we come up with one because that is the most important point of this meeting. One moment there is a question at the back.
169Mr. Yves Martin
170I have worked for many years on parietal art and I am an expert on the cave of Gouy, a small decorated cave that is the most northernmost in France. Earlier, you spoke of caves that may have disappeared. Well, Gouy Cave, which my brother and I discovered when we were children, is in a disastrous state, to such an extent that I submitted a file on this cave to the offices of Ms. Albanel the day before yesterday. It is currently overrun by roots. The first chamber, withe abundantly decorated walls, is completely covered with them. All these walls are engraved with fine incisions, paintings and other elements that are currently being studied. Some analyses were planned, which it was not possible to carry out before this invasion. The proliferation of roots is due to the incompetence of administrative officials who abandoned the conservation measures associated with this cave.
171I have some photos that can be projected… We are here at the heart of the subject of this symposium because it also concerns Lascaux and the preservation of our decorated caves.
172Mr. Robert J. Koestler
173Okay. I think this subject can be addressed with certain people later.
174Ms. Laurence Léauté‑Beasley
175I wanted to hear Mr. Antoine Danchin; he had begun to tell us his point of view when he was kind of interrupted and I would like to hear his answer. What is this project, or this method of exploration or diagnosis that you mentioned, and that is apparently very costly, but maybe also very interesting and promising?
176Mr. Antoine Danchin
177I will answer in English because I might make a point to the former comment. First about cancer, I hope that my example was very clear. We use chemotherapy because we hope to kill all the tumor cells. Unfortunately, in the present situation, we will not kill all microbes in a particular setting. I think this answers the question: we cannot try to use lethal methods on a global scale. With respect to the idea of genome studies, the underlying rationale is that if we know the genome of the most pathogenic agents, in this case fungi, we have access to the Achilles’ heel of the organism. It then becomes possible to find a solution to control their propagation. I think that there is one point we did not sufficiently discuss today and unfortunately I could not be here yesterday. This is melanin and the possible destruction of melanin. We might be able to kill two birds with one stone if we could directly attack melanin based on its physical properties. Are there any chemical physicists involved?
178Mr. Robert J. Koestler
179I can show the structure of melanin if somebody would like to see it. It is on one of slides. I do not know if there is someone here who studied melanin directly.
180Mr. Pascal Simonet
181Even if we manage to destroy all the organisms in a given location, contrary to what happens with cancer cells, the problem will return, because these sites will be recolonized.
182The question is not to know whether we can treat them‑‑there are always means of doing this, while being cautious with the paintings‑ ‑but how to prevent them from recolonizing. We are not in a sterile environment, far from it.
183Mr. Paul‑Marie Guyon
184Today, I would like to review with this group three points that deserve to be considered in this heated scientific debate.
185The first is related to the history of Lascaux at the time of the first attack. I was there in the late sixties to study the climatology at a time when the microbiologists of the time were there and the matter was urgent, as it is now. The difference is that when I was called upon to deal with the climatology of the cave, the algae were already disappearing. We saw the green algae stains disappearing, thanks to the very precise wall observations made by Doctor Bauer using a macrophotographical method. I do not remember whether the structure of DNA had already been discovered at that time, but we dabbed the affected areas with formalin. After a year and a half, to put it simply, the algae disappeared and have not returned. The only question that remained was that of how to keep the cave parameters stable, and I contributed to this with the climatic assistance system.
186For thirty‑five years nothing changed, and suddenly, in 2000, things began to change. It has been said during this conference that new machinery was introduced, etc. It is true, as Mr. Geneste said, that Fusarium solani has been found in the machine room.
187I am slightly skeptical, because Ms. Pallot‑Frossard has just said that the Fusarium that developed rapidly in the cave does not have exactly the same biological origin. This Fusarium had been latent in the strains, as you are all saying.
188For me, there is a mystery that I do not understand, namely the dynamic of these explosions. Does it have to do with air currents? Was the door not opened? Was the machine working a little too hard? I don’t think so.
189Was there not, by any chance, work going on at the time of the installation that could have taken up or moved the ground in the cave, which had been tamped down underfoot?
190The third point concerns Mr. Alabouvette’s comment and this seems to me to be the most important one for the future. You spoke about a very interesting discussion with Mr. Malaurent about the climate problem. I think this is crucial because you have all been speaking about the importance of the microclimate for the local development of microorganisms. Biologists say that if the surface is very damp, there will be particular conditions; if it is not very damp, or if it is slightly dry, there will be other conditions and other developments.
191We will never monitor the microclimate at the scale of 35 cm², as you have all said. The only thing that can be done is to carry out an overall verification on the basis of this famous idea of climatic assistance. When you take your samples and do your follow‑up with the LRMH, do you take visual readings at the same time, as Jacques Marsal did, on the hygrometric condition of the surfaces? You have been using this treatment for several. Have you correlated it, as you should have done, with the humidity of the air and the wall at the visual level? Someone like Jacques Marsal, or now Bruno Desplat, a trained guardian who knows all the details, would do so.
192Mr. Robert J. Koestler
193Please, go ahead.
194Ms. Geneviève Orial
195I will answer the first question concerning the propagation of Fusarium. We have indeed said that there was a violent explosion of it in September, during and after the restoration work. Unfortunately, there were many additional circumstances, and we also had to deal with very significant rainfall that occurred at the same time as the elimination of the roof that Roland Lastennet spoke about yesterday. This roof served to collect the first infiltration water and was in the process of being replaced at the time. At a certain moment, the old roof was no longer there and the new one was not yet in place. We cannot control the weather, and there was some extremely heavy rainfall and storms. This water, which is normally collected, reached the bottom of airlock 2. There was liquid water.
196Only a small change in the microclimate is needed for germination to start. The conditions at that time were very humid. Basically, after 30 years of perfect stability, this cave underwent a small change in its microclimate, which extended as far as the bottom of the cave and triggered the germination of strains that were not introduced by anyone, but which were there all the same.
197I cannot remember the second question.
198Ms. Isabelle Pallot‑Frossard
199The second question was about the work, but the work did not take place inside the cave, but mainly in the machine room. The ground that was treated with formalin, under which were species that were ready to germinate, has not been disturbed. I do not think that this corresponds to the reality of the work at all.
200The last question was whether the hydric condition of the walls is still being observed. It is, as far as I know. Sandrine van Sonlinge does this very regularly. Is it being done enough? Since we are not hiding anything at this conference, we can ask if we sufficiently draw on all the information that we have accumulated on this cave? Quite frankly, no. We are not working in an ideal way. The ideal way of working would be for all this information to be systematically correlated. It is a considerable job. We have to learn to work together and to share this information. We also have to find the ways and means to use these results statistically, since it is not easy to correlate the hundreds of thousands of climatic data with the hundreds of visual observations and the thousands of microbiological species that have been proven to exist.
201If there is an effort to be made in the years to come, and we are here to try and improve, it is to work on these ways of using the results from multidisciplinary teams which, for the moment, have been working, not solely on their own—they present their results to each other within the scientific committee—but without fully exploiting these data scientifically.
202We are open to all propositions concerning experiences, multidisciplinary methods, multiple and complex data, that have been developed in other domains that we do not know about, in the field of medicine, for example. We are not familiar with this kind of thing. If the experts in this room can give us some specialized advice on this kind of data exploitation that could guide us with our method, we could make a lot of progress.
203Mr. Robert J. Koestler
204Ralph Mitchell has a comment on this and then we will come back to the front.
205Mr. Ralph Mitchell
206I am actually a microbiologist and I have no objection to molecular analysis and in my own laboratory, we do a good deal of molecular analysis. I have a question; our focus at this meeting really has to do with protection of Lascaux and mostly protection against a micro‑biocontamination of the paintings, which is really the issue here. First of all, I have a question about molecular analysis. It good to have an understanding of the complexity of the microflora in the cave, but my experience as a micro‑ecologist is that knowing about this large and diverse population of microorganisms does not allow us to predict the appearance of another dominant organism in the bio‑film.
207Bio‑films are amazingly diverse and in a sense escape our control. One year you may have Fusarium dominant and another year you may have Cladosporium, or some other fungus, dominant. The issue is how do you predict and control the biological activity on the surface.
208I have also worked on biological control in a number of different contexts, including with Fusarium, and I would strongly recommend that you not employ biological control because every time any of us tried, we failed. The system is too complex; it is perhaps possible with a plant pathogen and a specific plant, but not in the ground and certainly not in this rather open ecosystem. The ultimate question in my mind is to know we can do in the short‑term, since Dr. Koestler is asking for recommendations. What can we do in the short‑term and what can we do in the long‑term? I agree with Dr. Warscheid that in the short‑term, biocides will provide some degree of control. Unfortunately when the organisms die, they provide nutrients for the next generation or the next dominant organism. But let’s return to the medical analogy of surveillance. We do very well in controlling human infectious disease through close surveillance and I think that it is a very important answer in the long‑run. But the surveillance really must be linked to the micro‑climates and we have to ask the question: why did this system stay so stable and free of dangerous infectious diseases in the early years and why not now? These are micro‑climates and each micro‑climate needs to be controlled and I think if we control the micro‑climate, and in addition have a very close surveillance, we may be able in the long‑run to keep the environment of Lascaux safe.
209Mr. Robert J. Koestler
210Thank you Professor Mitchell. Would anyone like to comment this subject because it is at the heart of the question of what we must do immediately. We do need to control and we need to survey. In the long term, we will need to study the ecology and try to understand the organisms and be able to predict which will be the next dominant one that we will have to pay attention to, but in the meantime, we have this immediate problem that is preying on us now.
211We must face the issue of the Cladosporium. We really cannot leave here thinking that we can do other studies while letting this one take hold.
212Mr. Thomas Warscheid
213First of all I have to thank Ralph Mitchell for his comments. I do not have to analyze the question from the medical point of view. I did not want to talk about cancer, but I about a kind of disease and this is how we understand the problem. Molecular techniques are also available in our lab, but we know from experience where the limits are. I want to come back to this strategy and to the subject of control; a very important point that we should also to discuss this afternoon is how we can intervene. I know and I said already that I want to do as little as possible in terms of biocide treatment, but we have learned through cleaning operations and biocide treatments over the last six months that, as is indicated by the ATP measurements, cleaning alone does not significantly relieve the infection.
214We have to combine this method with others. These data have also shown that we need a better biocide and we will develop something that is specifically adapted to this environment. If we can achieve this objective, we might also be able to reduce the cleaning interventions. But I must stress the fact that we have a biomass on the surface; it is there now. We cannot wait until it dies or disappears by itself. It must removed because it will always be a danger for other organisms to grow in maybe in 5 or in 10 or in 50 years, or maybe even in a shorter time. We have to discuss this issue very carefully in regards to conservation because I know this is a sensitive environment and we cannot easily touch and clean it. But we must discuss whether this is necessary or not. Perhaps some people believe that the organisms will disappear by themselves. But I have not seen that in the last 25 years.
215I think we must at least intervene by cleaning, as is done in Altamira. We have to consider this as well. And we could perhaps reduce other types of interventions as well if we were able to stabilize the climate— and I also want to stress this—in a manner that does not create a contradiction between molecular biology and our classic methods. We have seen that the change in humidity at the PR1 and PR2 points of this small project clearly modified the microflora; bacteria disappeared and fungi appeared. This is ecology and we must understand that climatic control plays an important role. But to return to my question, what about cleaning? Do we have to remove the bio‑film, or are some really convinced that we can leave it there for conservation purposes?
216Mr. Antoine Danchin
217I have just one technical question. Is it not possible to irradiate locally, using a very strong gamma source, for example?
218Ms. Isabelle Pallot‑Frossard
219That is a solution that we thought of right from the start. We thought about drastic solutions: methyl bromide, irradiation, UV, etc. However, there are secondary effects every time. Introducing a source to the inside of the cave is not very easy all the same. I would like to ask Mr. Heulin, who might have some ideas about the nuclear issues. In terms of safety and implementation in the cave, it is not simple.
220We also understood that we must not create a biological void because irradiation would, of course, not be specific and targeted, but global. The ideal would be to find a type of radiation that could allow us to inhibit them. This works for algae. For fungi, on the other hand, we are only at the beginning. This could be an idea, but without necessarily going as far as gamma.
221Mr. Max Schvoerer
222If Mr. Arai has been able to change the color of what he calls pigments, this is because he has changed the valence state of manganese and iron. Everyone knows that iron is red in the 3 plus state, and that it has grey to black colors in the 2 plus state.
223I would like to return to the last comment about gamma irradiation. There is a source, called americium‑241, that emits an alpha particle and a gamma ray of 60 KeV, meaning that it is thousands of times less energetic, which we can manipulate with precaution, and which can be targeted. This must not be done at Lascaux, but first in a laboratory cave for testing purposes. Such radiation does not change the valence state of manganese and iron, so it does not change the color.
224What is the effect of this on the support? The support is made of calcite. Irradiation changes the color of silicates because we create colored centers, but it does not change the color of calcite or aragonite, because we are only talking about calcite, but we must…
225Mr. Robert J. Koestler
226I think that your point is well made, that there is a possibility that certain studies can done, but another one quick comment Stefan?
227Mr. Stefan Simon
228Yes, very quickly, thank you Bob. I was quoted as saying that we know everything about Lascaux, probably due to a translation error, because what I meant to say is that I do not know another site where we know as much as we know about Lascaux. This is not the same thing. I think that over these three days we have learned that many things are still unknown and if I may say so, starting from this oldest museum‑laboratory in the world (107 years of tradition), I will like to draw your attention back to the year 1869 when Rudolph Virchow, the famous pathologist, founded the Anthropological Society in Berlin saying that all available sciences should contribute to the study of the preservation of our heritage.
229This morning, not being an expert in microbiology myself, I had the impression that in this discussion there is somewhat of a competition between molecular analysis and other methods in biology. I think that there is no reason for this competition. We do not need to go back to 1869; the Venice Charter from 1964 recommends the same thing: to call upon all the sciences that can contribute to the study. But if I may just give my conclusion of I heard as a non‑expert, I very much appreciated what was said by the Director of the LMRH concerning multidisciplinarity and a better integration of this data. We may have a lot of data but perhaps we have not sufficiently integrated them. I think that is the point on which we should focus our efforts, maybe in the afternoon session, to attain a truly multidisciplinary approach, starting from what is happening here; considering the opinions one by one to establish a collective consideration of ideas and issues that will lead to a collective conclusion. This is perhaps the best approach to adopt in order to obtain a better knowledge of Lascaux.
230Mr. Robert J. Koestler
231I think that is an excellent approach: bring all the bibliographic references together in one place because there are studies that we have and others that we do not have and vice versa. We need to have access to all excellent suggestions in order to advance. Is there a quick comment?
232Mr. Jean‑Michel Geneste
233I will have to go back to two points of information that I would like to present so that they will not remain unanswered. With regard to cleaning interventions in the cave, it is true that this has been an important element. There was a critical phase during which systematic cleaning, especially of the ground after the spreading of lime and with the injector/ extractor, which was introduced for cleaning not only the ground, but also the walls up to the edges of the decorated areas, meaning the most resistant areas, was a very significant element for overcoming the first Fusarium attack. We are aware of that and it is certainly important. Whether a lot of residue or dust remains on the walls today is another question. We have removed as much as possible of what was deposited during the major visiting period of the cave between the 1960’s and 2001, which had never been cleaned.
234The second point I would like to make relates to infiltration waters. Roland Lastennet reminded us yesterday that the infiltration water in the cave has a long history on the surface and a relatively slow circulation rate. This could explain the high concentration that he observes in some materials. However, in this location we are almost on a hill terrace and agricultural practices were abandoned long time ago. The preservation of the cave implies maintaining it in its environmental setting and we must pay particular attention to monitoring what happens on the surface in terms of agriculture and maintaining the vegetal cover, which is vital for a proper ecosystem and water circulation.
235I wanted to clarify this. We are thus not in an environment where we will be able to cover and protect the entire surface. We would be wrong to do so. On the contrary, we must maintain this environment with the most natural ecological activity possible.
236Mr. Robert J. Koestler
237May I interrupt you? I am going to have to stop us now because we are going to leave, but I would like to say a couple of things. What we were talking about now is more the intermediate or longer term issues for which we have a little bit of time to move forward on.
238The immediate problems, according to what I have heard—and I am going to stick my neck out, but you can disagree if you want—are that these Cladosporium must be removed, and that to do this you have to use a biocide as quickly as possible because the arm of the cave is dying. It may not be the heart of Lascaux, but it is certainly the arm or the appendage of Lascaux that is dying because we are not acting on it now. There is another aspect, I think, because I understood that there is a favorable change in the cave concerning the doors and that the imbalance of the environment may have appeared following the removal of some of the doors. It is perhaps not the new air conditioning system that is bad; it may just be that the balance that maintained the humidity in the side chamber, where there is now Cladosporium, was disturbed.
239What I hear today; and all the information I have received on the short term issues, indicate that we should reinstall those doors and see if we can reestablish the former equilibrium. I may be wrong, but I think it is time now to say: “Let’s try this!” You can follow the evolution rapidly and see if a monitoring system can be put into place. It will then be necessary to reduce the number of visits in the cave in order to increase the ecological diversity with the goal of establishing a better balance of the organisms inhabiting the cave. But this is a long term strategy; this will be done in association with actions related to the hydrology of the cave. This is much more difficult since it is not easy to say what is correct or not because there are several different specialties involved, but I think more long term studies are necessary for this. I think it might also be useful to install some enclosed UVC lamps. They do not irradiate the surface and they remove elements from the air to help reduce the chance of re‑infestation for now, while you try to find a solution to the problems in the cave. They are very effective and act rapidly against bacteria, viruses and fungi, as well as particles, depending on the case. I really think it is necessary to give yourselves some breathing space in order to take control of the situation. The Fusarium is under control, from what I have heard, but not the Cladosporium. This what I suggest you do to get the situation under control, to give yourselves a little breathing time to let the long term studies make their contribution to the cave as a whole and to determine the possibilities for improving the overall health of the cave while you are treating the appendage. I think we must all move on and you can beat me up later.
240Thank you to all, the panel and participants.
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