Putting algae and seaweed on the menu could help save our seafood

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This article was written by Pallavi AnandThe Open University and Daniela SchmidtUniversity of Bristol Cabot Institute. 

If we have to feed 9.8 billion people by 2050, food from the ocean will have to play a major role. Ending hunger and malnutrition while meeting the demand for more meat and fish as the world grows richer will require 60% more food by the middle of the century.But around 90% of the world’s fish stocks are already seriously depleted. Pollution and increasing levels of carbon dioxide (CO₂) in the atmosphere, which is making the oceans warmer and more acidic, are also a significant threat to marine life.There is potential to increase ocean food production but, under these conditions, eating more of the species at the top of the food chain, such as tuna and salmon, is just not sustainable. As a recent EU report highlighted, we should instead be looking at how we can harvest more smaller fish and shellfish, but also species that aren’t as widely eaten such as seaweed and other algae.The oceans have absorbed around one third of the CO₂ emitted into the atmosphere since the Industrial Revolution. The absorbed CO₂ goes through a series of chemical reactions that form carbonic acid and lower the pH of the water. These reactions also reduce the concentration of carbonate ions, which are vital for those creatures that grow external skeletons such as corals and shellfish.

The acid and the lack of carbonate mean these organisms form weaker skeletons and have to use more energy to do so, leaving less energy for growth and reproduction. Consequently, they up smaller in size. Aside from the impact this has on shellfish, several of the species affected, such as corals in the tropics or coralline algae in the waters around the UK, also play a key role in providing food and nursing grounds for fish. And less fish food leads to fewer fish for us to catch.

Climate change is affecting food production

The impact of ocean acidification varies widely across the globe. But it is already affecting marine food production, particularly of shellfish. For example, CO₂-rich water along the west coast of the US means more oysters in local hatcheries are dying when they are still larvae.
Warmer seas due to climate change are also affecting food supplies. Some species are moving towards the poles in search of cooler water, forcing fishermen into more northerly waters or leaving them without stocks altogether. Some fishing fleets in northern locations will find more fish available but many will see the amount of fish available to catch fall by between 6% and 30% depending on the region. The biggest impact will be on areas that are already the most dependent on fishing, such as Southeast Asia and West Africa.

One possible solution is to eat more smaller fish and shellfish such as mussels. Large fish need to eat smaller fish to grow. If we eat smaller fish instead then we remove a step from the food chain and reduce the amount of energy lost in the process. What’s more, it might become easier to farm these smaller fish because the algae, cyanobacteria and other plankton they eat could actually benefit from warmer waters and higher levels of CO₂ in the atmosphere. This is because they get their energy from photosynthesis and so use CO₂ like fuel.

Spirulina, the new seafood cocktail.

It might also be possible to take this a step further and add some of these organisms directly to our diet, giving us an abundant new source of food. Seaweed, for example, is a type of algae that has been eaten for centuries, but only 35 countries commercially harvest it today. Spirulina cyanobacteria is already eaten as a food supplement and several companies are trying to turn other forms of algae into a human food source.

Farming these organisms in the right way could even help counter some of the effects of climate change on the rest of the food chain. For example, growing more seaweed lowers the amount of CO2 in the surrounding water, reduces acidification, and improves the environment for oysters and other shellfish. Managing seaweed harvest correctly will also maintain the dissolved oxygen and nutrient levels in the water, contributing to the overall health of the ocean.

The ConversationMaking algae a common part of more people’s diets won’t be easy. We need to ensure that any new algae food products on our dinner plates have the needed nutritional value but are also attractive and safe to eat. But sticking with our traditional salmon and tuna diet isn’t sustainable. Expanding our seafood menus could be a vital way of keeping the ocean healthy while it supplies the food we need.
Pallavi Anand, Lecturer in Ocean Biogeochemistry, The Open University and Daniela Schmidt, Professor in Palaebiology, University of Bristol

This article was originally published on The Conversation. Read the original article.

Unless we regain our historic awe of the deep ocean, it will be plundered

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Image credit: BBC Blue Planet

In the memorable second instalment of Blue Planet II, we are offered glimpses of an unfamiliar world – the deep ocean. The episode places an unusual emphasis on its own construction: glimpses of the deep sea and its inhabitants are interspersed with shots of the technology – a manned submersible – that brought us these astonishing images. It is very unusual and extremely challenging, we are given to understand, for a human to enter and interact with this unfamiliar world.The most watched programme of 2017 in the UK, Blue Planet II provides the opportunity to revisit questions that have long occupied us. To whom does the sea belong? Should humans enter its depths? These questions are perhaps especially urgent today, when Nautilus Minerals, a mining company registered in Vancouver, has been granted a license to extract gold and copper from the seafloor off the coast of Papua New Guinea. Though the company has suffered some setbacks, mining is still scheduled to begin in 2019.

Blue Planet’s team explore the deep. Image credit BBC/Blue Planet

This marks a new era in our interaction with the oceans. For a long time in Western culture, to go to sea at all was to transgress. In Seneca’s Medea, the chorus blames advances in navigation for having brought the Golden Age to an end, while for more than one Mediterranean culture to travel through the Straits of Gibraltar and into the wide Atlantic was considered unwisely to tempt divine forces. The vast seas were associated with knowledge that humankind was better off without – another version, if you will, of the apple in the garden.

If to travel horizontally across the sea was to trespass, then to travel vertically into its depths was to redouble the indiscretion. In his 17th-century poem Vanitie (I), George Herbert writes of a diver seeking out a “pearl” which “God did hide | On purpose from the ventrous wretch”. In Herbert’s imagination, the deep sea is off limits, containing tempting objects whose attainment will damage us. Something like this vision of the deep resurfaces more than 300 years later in one of the most startling passages of Thomas Mann’s novel Doctor Faustus (1947), as a trip underwater in a diving bell figures forth the protagonist’s desire for occult, ungodly knowledge.

An early diving bell used by 16th century divers. National Undersearch Research Program (NURP)

Mann’s deep sea is a symbolic space, but his reference to a diving bell gestures towards the technological advances that have taken humans and their tools into the material deep. Our whale-lines and fathom-lines have long groped into the oceans’ dark reaches, while more recently deep-sea cables, submarines and offshore rigs have penetrated their secrets. Somewhat paradoxically, it may be that our day-to-day involvement in the oceans means that they no longer sit so prominently on our cultural radar: we have demystified the deep, and stripped it of its imaginative power.

But at the same time, technological advances in shipping and travel mean that our culture is one of “sea-blindness”: even while writing by the light provided by oil extracted from the ocean floor, using communications provided by deep-sea cables, or arguing over the renewal of Trident, we perhaps struggle to believe that we, as humans, are linked to the oceans and their black depths. This wine bottle, found lying on the sea bed in the remote Atlantic, is to most of us an uncanny object: a familiar entity in an alien world, it combines the homely with the unhomely.

Wine bottle found in the deep North Atlantic. Laura Robinson, University of Bristol, and the Natural Environment Research Council. Expedition JC094 was funded by the European Research Council.

For this reason, the activities planned by Nautilus Minerals have the whiff of science fiction. The company’s very name recalls that of the underwater craft of Jules Verne’s adventure novel Twenty Thousand Leagues under the Seas (1870), perhaps the most famous literary text set in the deep oceans. But mining the deep is no longer a fantasy, and its practice is potentially devastating. As the Deep Sea Mining Campaign points out, the mineral deposits targeted by Nautilus gather around hydrothermal vents, the astonishing structures which featured heavily in the second episode of Blue Planet II. These vents support unique ecosystems which, if the mining goes ahead, are likely to be destroyed before we even begin to understand them. (Notice the total lack of aquatic life in Nautilus’s corporate video: they might as well be drilling on the moon.) The campaigners against deep sea mining also insist – sounding not unlike George Herbert – that we don’t need the minerals located at the bottom of the sea: that the reasons for wrenching them from the deep are at best suspect.

So should we be leaving the deep sea well alone? Sadly, it is rather too late for that. Our underwater cameras transmit images of tangled fishing gear, cables and bottles strewn on the seafloor, and we find specimens of deep sea animals thousands of metres deep and hundreds of kilometres away from land with plastic fibres in their guts and skeletons. It seems almost inevitable that deep sea mining will open a new and substantial chapter on humanity’s relationship with the oceans. Mining new resources is still perceived to be more economically viable than recycling; as natural resources become scarcer, the ocean bed will almost certainly become of interest to global corporations with the capacity to explore and mine it – and to governments that stand to benefit from these activities. These governments are also likely to compete with one another for ownership of parts of the global ocean currently in dispute, such as the South China Sea and the Arctic. The question is perhaps not if the deep sea will be exploited, but how and by whom. So what is to be done?

A feather star in the deep waters of the Antarctic. BBC NHU
Rather than declaring the deep sea off-limits, we think our best course of action is to regain our fascination with it. We may have a toe-hold within the oceans; but, as any marine scientist will tell you, the deep still harbours unimaginable secrets. The onus is on both scientists and those working in what has been dubbed the “blue humanities” to translate, to a wider public, the sense of excitement to be found in exploring this element. Then, perhaps, we can prevent the deep ocean from becoming yet another commodity to be mined – or, at least, we can ensure that such mining is responsible and that it takes place under proper scrutiny.
The sea, and especially the deep sea, will never be “ours” in the way that tracts of land become cities, or even in the way rivers become avenues of commerce. This is one of its great attractions, and is why it is so easy to sit back and view the deep sea with awed detachment when watching Blue Planet II. But we cannot afford to pretend that it lies entirely beyond our sphere of activity. Only by expressing our humility before it, perhaps, can we save it from ruthless exploitation; only by acknowledging and celebrating our ignorance of it can we protect it from the devastation that our technological advances have made possible.-
This blog is written by Laurence Publicover, Lecturer in English, University of Bristol and Katharine Hendry, Reader in Geochemistry, University of Bristol and both members of the University’s Cabot Institute. This article was originally published on The Conversation. Read the original article.