Tag Archives: caves

Even underground ecosystems are being influenced by humanity

Not even underground systems are free from the effects of pollution, according to a new study.

A cave in the Municipality of Quezon, Philippines (not Monte Conca).
Image via Wikipedia.

The research focused on the Monte Conca cave system, a sprawling gallery of springs and pools below a nature preserve in Sicily. According to the team, despite its isolation underground, even the Monte Conca system shows signs of changes in its microbe communities with species associated with human waste.

Nowhere to hide

Monte Conca is Sicily’s longest and deepest gypsum karst system and was dug out by sulfuric acid eating into the rock. It’s not a unique occurrence, and caves of this type have been found throughout the world.

Given how secluded it is, the system was believed to be pristine, but pollution seems to make an impact even here. The team reports that the cave system experiences seasonal changes in microbial communities between its wet and dry seasons. Their results suggest that such changes are driven by surface water percolating through soils beneath agricultural and urban areas that collect contaminants and deposit them in the cave.

These chemicals then alter the makeup of the cave’s microbial communities.

While the research focused on the Monte Conca spring pool, the team says it’s indicative of the impact surface runoff has on cave microbes throughout the world. Exactly what the long-term effect of these changes will be is not well known, says lead author Dr. Madison Davis of USF’s Department of Cell Biology, Microbiology and Molecular Biology.

During the dry season, biological activity in the cave is dominated by sulfur-oxidizing bacteria, which mix oxygen from the cave with hydrogen sulfide in the water for energy. They represent over 90% of the bacteria in this ecosystem.

After heavy rainfall, however, (which is especially likely during the wet season), this type of bacteria was overshadowed by surface-derived species which the team identified as being primarily human-associated strains, including Escherichia coli and other fecal bacteria.

One sampling (the team took four samplings between 2015 and 2016) appeared to show a transition between the wet and dry seasons when potential man-made contaminants (such as Escherichia and Lysinibacillus), sulfur-oxidizing bacteria, and nitrogen-fixing bacteria all were present within the spring pool after heavy rains. This helped show that what the team picked up on was indeed the effect of surface events and not a natural occurrence in the cave.

The paper “Surface runoff alters cave microbial community structure and function” has been published in the journal PLOS ONE.

A simple nettle. This one has plenty of light, though.

Ice age relics still alive in China’s darkest caves

In the darkest caves of  southwest China, one can experience fragments of the long set Ice Age and travel back in time 30,000 years. No, there isn’t any time machine or stargate of some sort (scientists say time travel is impossible, I beg to differ), instead what you’ll find in one of the darkest corners of the Earth is an ecosystem so perfectly preserved, that its vegetation is practically unchanged since the last ice age.

A simple nettle. This one has plenty of light, though.

A simple nettle. This one has plenty of light, though.

Part of a joint scientific effort between researchers from southwest China and UK,  scientists have identified seven species of nettle that grow in isolated, dark corners of the karst landscapes of Guangxi and Yunnan provinces. The nettles are only found in the darkest corners of the provinces’ caves and gorges, places where barely any sunlight ever shines. In fact, some survive in conditions in which just 0.02 per cent of sunlight penetrates the cave, a characteristic similar only to deep ocean vegetation.

Actually, one of the discovered species, Elatostema retrorstrigulosum, is limited to only 10 adult plants, which makes it “critically endangered” under the criteria of the International Union for Conservation of Nature.

“They grow at the backs of the main caverns in near-dark conditions. There must be something quite special about their photosynthesis. They probably activate the photosynthetic process very quickly, which enables them to take advantage of very short bursts of light, and they might go for slightly different wavelengths. [They could be] relics of a vegetation from a previous cooler climate that resembled that of the caves, ” says Natural History Museum researcher Alex Monro.

The last part is the most interesting of course. You see, all around these caves one can find typical tropical vegetation, where as the vegetation found in these caves is totally opposite from any specs one might expect to find.

It’s conceivable that the nettles evolved completely independently of the surrounding area, meaning they arose independently in the cave. The only problem with this hypothesis is that the cave is only 1 million years old, too short of a period on the evolutionary scale, so this assumptions kinda falls off the table. The only other possible explination is that they’re actually “relicts of a vegetation from a previous cooler climate that resembled that of the caves”, as Monro suggests. There you have it, 30.000 years and nothing’s changed. Mammoths, anyone?