New species of fish are being discovered in what’s being referred to as the Rariphotic zone. Deep reef ecosystems could still be explored much more.
It’s always been there, but a layer of the ocean is so distinct from the waters above and below it that it needed its own category.
Scientists have just defined the newly named rariphotic zone, a layer of ocean between depths of 130 and 300 metres (400 and 1,000 feet) – a low-light or “twilight zone” in deeper reef regions.
It sits just below the mesophotic zone, between 40 and 150 metres (131 and 492 feet), where medium light penetrates – the optimal waters for tropical coral reefs. And it’s teeming with previously unknown fish – a whole newly discovered ecosystem.
These fish are closely related to reef fish, which researchers didn’t think could live below the mesophotic.
This has led to a hypothesis that the new rariphotic zone may be a refuge for shallower reef fishes seeking respite from the warming waters and coral deterioration caused by climate change.
There’s a lot we don’t know about the ocean, simply because it’s so difficult for us to access. It was only thanks to advances in submersible technology that marine scientists have been able to explore down below the reef off the coast of Curaçao.
“It’s estimated that 95 percent of the livable space on our planet is in the ocean, yet only a fraction of that space has been explored,” said study lead author Carole Baldwin of the NMNH.
“That’s understandable for areas that are thousands of miles offshore and miles deep. But tropical deep reefs are just below popular, highly studied shallow reefs – essentially our own backyards. And tropical deep reefs are not barren landscapes on the deep ocean floor: they are highly diverse ecosystems that warrant further study. We hope that by naming the deep-reef rariphotic zone, we’ll draw attention to the need to continue to explore deep reefs.”
Harmful algal blooms are often caused by nutrient pollution via overused chemicals such as phosphorous. These algal blooms regularly represent threats to water-based freshwater ecosystems, and so it’s useful that a solution to this problem is being introduced more.
A cheap, safe and effective method of dealing with harmful algal blooms is on the verge of being introduced following successful field and lab tests.
Moves to adopt use of hydrogen peroxide (H2O2) as an effective treatment against toxic algae are already underway following the results of new research by a team from the John Innes Centre and the University of East Anglia (UEA.)
Successful trials last summer showed that H2O2 was effective against the golden algae, Prymnesium parvum. This is responsible for millions of fish kills worldwide each year and a threat to the £550m economy of the Broads National Park where trials are taking place.
Now follow up lab tests have demonstrated that controlled doses of the versatile chemical compound could be even more effective in dealing with cyanobacteria commonly known as blue green algae — a major public health hazard and potentially fatal to dogs and livestock.
Some of these exciting results are published today in the journal Biochemical Society Transactions along with a series of other scientific developments related to algal communities in the Broads National Park; one of the UK’s most popular and environmentally important network of waterways.
Dr Ben Wagstaff, one of the authors of the study from the John Innes Centre said: “We’ve demonstrated that the use of hydrogen peroxide is a practical, relatively easy way of managing these blooms.
“Work has already started to put together protocols for the use of hydrogen peroxide to control Prymnesium and our research showed that blue green algae are even more susceptible. You can potentially use even lower doses to wipe out blue-green blooms.”
The work in the Broads National Park could have widespread implications for the way harmful algal blooms are managed in waterways worldwide.