Xabier Rubio: “Amphibians have disappeared due to habitat decline”
Xabier Rubio: “Amphibians have disappeared due to habitat decline”
Are amphibians disappearing? In what situation are they in the world?
In general yes. It is evident that they are disappearing. Populations are in decline and it is not known why it is occurring. There are many factors. Researchers began to worry about the discovery of some species from Central America, South America and Australia, which soon discovered that the population was declining. A year after being discovered, for example, in places where there were thousands of copies, they were completely missing or only some remained. This caused the alarm, especially because some of these species were very striking.
Some unknown factors have been found but in general it is not known why it has occurred. It seems that climate change has something to do with it and much has been said about it, but the history of this problem is quite new and therefore it is still uncertain why, in certain cases yes but not in general.
Is it a natural or human situation?
It is not known in all cases. In some places there are no remains of causes of extinction. The problem is that many populations have not been investigated beforehand and neither do we know their dynamics. But in many places it has become clear that the disappearance of amphibians has much to do with the activity of society. Amphibians disappear worldwide due to declining habitats. The masses of water, wells and lakes have dried up and contaminated. Many species do not admit contamination. But when they are not contaminated, these places are dried up or used for other things.
On the other hand, pesticides and other substances used also influence, since amphibian foods are reduced, especially insects. In addition, these substances are toxic. Keep in mind that amphibians have a special skin, it is not the real skin but the mucosa, since they have the ability to breathe on the surface. This somehow makes them more vulnerable.
It has been observed that in some areas ultraviolet radiation is also related. Some man-contaminated fungi, the chitridia, have also been found. It is a very serious problem, the first case has already been found in the Iberian Peninsula. Unfortunately, it seems that in some places they are infected by scientists, because it was not known. Now, on the contrary, very strict measures are taken, all materials are disinfected, the same material is transported from one place to another, etc. It seems that the hyphae of this fungus develop on the surface of the amphibian, hinder breathing and amphibian dies. In a very short time thousands can die, for example in a few weeks, so mortality rates increase considerably.
There are other factors: cutting vegetation they need, fires, etc. But perhaps most importantly, amphibians need a damp place to reproduce. If the water disappears and the wells dry, they disappear quickly.
What about all species?
I think in general all amphibians are decreasing. But some species are omnipresent, that is, they are found everywhere. They usually have few problems, as they find a playsite or another easy one. However, also in very common species in the Basque Country (common frog, palate triton, …) cities are conquering the places that were previously reproducing and are disappearing. In no case are they in danger, but it is a problem to consider because they may be in danger if we take away their habitats.
The case of the southern frog stands out. What is the current situation?
The tree frog is a special case, because it is not widespread in the Basque Country. In southern Spain there is a lot, but here is a very special case. It has to do with ancient, more Mediterranean climatology. We have other examples, such as cork oak and art, since formerly the climate was more suitable for these species. Hence the name of the frog, which rose from the water to the trees and to those plants of tropical flavor.
In a time, the frog was distributed throughout the Basque Country, and gradually, both by the climate and by other species, they have been limited to certain places. They are also found in the fields, as this territory has a fairly Mediterranean climate, and there is a bridge between the populations of the Mediterranean and the Landes. In this bridge the population is also decreasing and, in addition, there are cuts.
The tree frog here has been isolated, the nearest population may be from the north, but it is many kilometers away and has no relationship. We want to do a genetic study to know if, together with those in the south, they formed the same population. I do not think that the population has endogamy problems, since the number of specimens is not very small, but it is clear that it can be created. Genetic variability will be less than in other populations; all frogs will be to some extent ‘similar’. Yes, and if it is in danger or not, the genetic study will tell.
Are there other relevant cases?
In principle there are interesting populations, but there is no other case like the frog. It is very interesting, for example, the Pyrenean Triton, very abundant in Navarre and throughout the Pyrenees, but that here lives in few places. It inhabits some wells in the Leitzaran valley, but they are few. Another interesting case is that of the summit tritons. The populations left in our mountains are not very good. For example, those in Aralar are few and have many problems. The corridor toad is located in Txingudi, Álava and Navarra, and lives in the surroundings of the area. Before it was abundant on the coast, but it has almost disappeared. Txingudi is a very curious case, as there are still many specimens. In fact, it is classified as vulnerable in our Community.
Can we say that amphibians are "obsolete" in evolution?
It may be, but the trend to extinction in most populations is accelerating. I think, in that case, it should be a process of many years.
It is estimated that between 10 and 100 million species can exist and only a million are known. Many species are not yet known, most are invertebrates: insects, fungi, bacteria, etc. Many of them disappear as they are known. Therefore, I do not think that the process that is taking place is natural.
What is the origin of amphibians? It is not clear whether they are aquatic, terrestrial or both. Can it be said that they have been halfway through the evolution of water to earth?
Keep in mind that others have returned to the water after passing to land, such as whales and dolphins. These animals are more developed than amphibians, they are superior mammals.
What kind of research and projects are being developed in the world to analyze the problem and perhaps seek solutions?
I don't know if it is global, but at least in Europe there is an organization that handles this problem: DAPTF (Declining Amphibian Population Task Force). There are also other groups. We also want to create a group around this topic to strengthen relationships with existing groups, open communication channels and facilitate the dissemination of information. Thus, we would share the research and strategies we do with other groups. We could discuss what measures should be taken for conservation and create a protocol to standardize activities. Research is usually timely, but some populations require fifteen, twenty or thirty years to remain.
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