SNIPPETS

A river runs through it...

A subterranean river said to be flowing beneath the Amazon region of Brazil is not a river in the conventional sense, even if its existence is confirmed. The “river” has been widely reported after a study on it was presented to a Brazilian science meeting recently. But researchers say the water was moving through porous rock at speeds measured in inches per year – not flowing. Another Brazilian expert said the groundwater was known to be very salty.

Valiya Hamza and Elizabeth Tavares Pimentel from the Brazilian National Observatory deduced the existence of the “river” by using temperature data from boreholes across the Amazon region. The holes were dug by the Brazilian oil company Petrobras in the search for new oil and gas fields, and Petrobras has since released its data to the scientific community.

Using mathematical models relating temperature differences to water movement, the scientists inferred that water must be moving downward through the ground around the holes, and then flowing horizontally at a depth of several kilometers. They concluded that this movement had to be from west to east, mimicking the mighty Amazon itself.

A true underground river on this scale – 6,000 kilometers long – would be the longest of its kind in the world by far. But Professor Hamza said that it was not a river in the conventional sense. “We have used the term ‘river’ in a more generic sense than the popular notion,” he said. In the Amazon, he said, water was transported by three kinds of “river” – the Amazon itself, as water vapour in atmospheric circulation and as moving groundwater.

“According to the lithologic sequences representative of Amazon (underground sedimentary) basins, the medium is permeable, and the flow is through the pores. We assume that the medium has enough permeability to allow for significant subsurface flows.”
 
Climate change boon to UK seafood
The United Kingdom’s waters may become more productive fishing grounds as climate change brings new species in from the south, according to researchers. Fish such as red mullet, hake and sole have become more abundant in the last 30 years, as the waters have warmed. But established favourites such as cod and haddock may be on the wane.

The findings come from an analysis of trawl data going back to 1980, covering about 100 million fish caught, and is published in Current Biology. “This is the first attempt that’s brought together many different data sets,” said project leader Steve Simpson from Bristol University.

“People have been reluctant to piece together data from lots of different surveys because there are some tough challenges there. But we spent about a year doing it, and it really gives us the first comprehensive look at (the effects of climate change on) fish in European shelf waters.”

The relatively shallow waters of the European continental shelf include those around the UK and Ireland, spanning the North Sea, English Channel and Irish Sea. Overall, three-quarters of the species in the area are responding to rising water temperatures, the team found. And of those, three times as many are increasing in abundance as declining.

Previous studies have also indicated that species such as haddock and mackerel are moving northward in response to warming – a situation that led to last year’s “mackerel war” between Iceland and the European Union, with Scotland especially vociferous in protest against the Icelandic quota.

The team behind this study – drawn from eight UK research institutes and one in the Irish Republic – emphasises there is no guarantee that abundances of these species will continue to rise. Each one needs not only water of a given temperature range but also factors such as a secure food supply and the right environment for reproduction.

The impact of ocean acidification is also unknown, but unlikely to be beneficial given the evidence so far.  But if warming water is the main factor, the trends seen over last three decades are likely to continue, because further temperature increases are expected.

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