ark in the sky vol 2 no 2

The state of our oceans

Fish

Coral

Tides

El Niño

Ocean plastic

Melting ice & oceans

plus ...

Whales

Dolphins

Sharks

Portuguese man-of-war

News

Your questions

Quiz & events

Volume 2 no2

Ark in the Sky

Ocean special

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Editor: Ita McCobbEditorial team: Richard Casna, Jennifer Hope-Morley, Elizabeth Rigby, Thomas P Sawyer.Photographs: Unless otherwise stated, all images are copyright Ark in the SkyDesign & layout: imcicE-mail: [email protected]: www.arkinthesky.org

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It is obvious that we while may think we understand nature there are many more complex long-term relationships within nature and the way it functions that we have still to comprehend.

Consider our oceans: according to UNESCO, our oceans make up over 90% of habitable space on our planet and 50-80% of all life on Earth is to be found there … and yet for most of us they remain something of a mystery.

They say that all life on Earth is said to have had its origins in the sea. This is why we have decided to dedicate this special issue to oceans and what we currently know about how important they are in maintaining the ecological balance of our world.

As Ben Halpern, University of California environ-mental science professor, pointed out, “Every single person on the planet benefits from the health of the ocean, but most don’t realize it.” But with 60% of the world’s major marine ecosystems being degraded or being used unsustainably we clearly need to reconsider how we interact with our oceans.

The research for this issue has been a real eye-opener, particularly the enormous variety of life to be found in our oceans and the way what happens there impacts on life on terra firma. Although the fact that marine biologists continue to use a

vocabulary alien to the rest of the world doesn’t help in understanding the problems and possibilities.

Shockingly, while sharks make news around the world killing on average 3 people per year, the fact that more than 100 million sharks (yes, 100,000,000!) are killed each year goes largely unnoticed.

Coral reefs, some of the world’s most diverse ecosystems – the “rainforests of the sea” – occupy less than 1% of the ocean floor but support about 25% of all marine species. Despite their importance, coral reefs are still one of the most complex and poorly understood ecosystems in the world.

The good news is though that governments around the world are becoming aware of the problems and are designating great stretches of ocean as Marine Protected Areas (MPAs). World Heritage marine sites now represent one third of all marine protected areas in terms of surface area.

As oceans are finally beginning to be noticed and better understood, research is moving apace. A marine biotechnologist has created artificial blood built on the haemoglobin of simple marine worms that is compatible with all blood groups! Let’s hope this is one of those discoveries that not only benefits mankind but also respects the complex long-term relationships within nature.

Ita McCobb

It’s time to force our heads out of the sand!Specialists to name images:plants

animalsbirds

insects

4 www.arkinthesky.org

ResourcesThe state of our oceans: NOAA; UNESCO; Marinebio Conservation Organization; The Oceanographic Museum of Monaco; Juliet Eilperin, The Washington Post 17 June 2014; Associated French Press (AFP) 18 June 2014. Whales: IUCN Red List; NMFS, NOAA fisheries; whale.org; National Geographic; bbc Wildlife; United Nations (UN); Oxford English Dictionary, Oxford University Press. Dolphins: Sea Life Park, Hawaii; Museum of Osteology; bbc World Service; Proceedings of the National Academy of Sciences; St Andrews University Sea Mammal Research Unit; NOAA. Coral: coral.org; nationalgeographic.com; wwf.panda.org; nhm.ac.uk.Fish in the ocean: IUCN Redlist; NOAA; Fisheries Research Report 2013; Oxford English Dictionary, Oxford University Press; Ocean Health Index; The Oceanographic Museum of Monaco. Tides: UK Met Office; NOAA; NASA; World Meteorological Organization (WMO).

Editor’s message page 3

State of our oceans 6

Whales 9

Dolphins 10

Coral 11

Fish in the ocean 14

Tides 17

Quiz 20

contents


¿es el Niño?: The Met Office; NASA; NOAA; UNESCO; World Meteorological Organization (WMO); International Research Institute for Climate and Society (IRI).Portuguese man-of-war: New Scientist; NOAA; National Geographic; The Oceanographic Museum of Monaco.Sharks: NFESC/NOAA; William C Hamlett, Sharks, skates, and rays: the biology of elasmobranch fishes, Johns Hopkins University Press; Shark Research Organization; WWF; Greenpeace; Global Shark Attack File. Plastic in our ocean: Times of India; Marine Debris; Bloom Association; Clean Ocean Action; CSV; Recycle Now; Waste Watch. World Health Organization; “Would You Like a Bag With That?” a Swiss exhibition; Malaspina Expedition study report.Melting ice and oceans: NASA online, Form and position of sea level, with special reference to its dependence on superficial masses symmetrically disposed about a normal to the earth’s surface, US Geological Survey No 48; Nature Geoscience, 2012 vol. 3; J Mitrovica, Harvard University; Stephen Battersby, New Scientist, 4 May 2013.Who stole our ozone?: NASA Goddard Space Flight Center, Maryland; Montreal Protocol.

contents continued

¿es el Niño? 23

Portuguese man-of-war 25

Sharks 26

Plastic in our oceans 27

Melting ice & oceans 28

Blogit 30

Events 31

Who stole our ozone? 32

Strangely enough, more is known about the entire surface of Mars than the surface of Earth, in particular our vast oceans!

cAccording to UNESCO, our oceans make up over 90% of habitable space on our planet and 50-80% of all life on Earth is to be found in them. Ocean species are all part of the essential biodiversity of our planet – each has a role to play in maintaining our ecosystem.

Our oceans contain not only thousands of exquisite fish species but also barnacles, birds, corals, dolphins, eels, jellyfish, molluscs, octopi, planktons, seagrasses, sharks, sponges, squid, turtles, whales and worms to name but a minute few of the millions of species that have been found there – many of which are major food sources for all of us.

We all benefit “Every single person on the planet benefits from the health of the ocean, but most of them don’t realize it,” commented Ben Halpern, environmental science professor at the University of California.

Which is why Marine Protected Areas (MPAs) are being created to conserve the biodiversity of the oceans and to maintain productivity, especially of fish stocks. World Heritage marine sites now represent one third of all marine protected areas in terms of surface area.

The most recent proposal relates to the U.S. Pacific Remote Islands Marine National Monument, which would be expanded from almost 87,000 square miles to nearly 782,000 square miles within the Central Pacific Ocean. The designation would include waters up to 200 nautical miles offshore from the territories.

According to Enric Sala, a National Geographic explorer-in-residence who has researched the area’s reefs and atolls since 2005, “It’s the closest thing I’ve seen to the pristine ocean.”

The UK government is also considering creating a sanctuary that would be centred round the Pitcairn Islands – those Pacific islands inhabited by the 56 remaining descendants of the mutineers from the HMS Bounty in 1789.

Anote Tong, president of the small Pacific island nation of Kiribati, recently announced that he will close an area roughly the size of California to commercial fishing by the end of 2014. “It’s our contribution to humanity,” he said.

Kiribati lies on average only seven feet above sea level. Scientists agree that it’s drowning and within a century is likely to become totally submerged in the Pacific Ocean.

The threats to our oceans While approximately 12% of our territories on land are protected only roughly 1% of the world’s oceans and seas are protected.

Without significant changes, more than half of the world’s marine species may stand on the brink of extinction by the dawn of the next century.

Today, 60% of the world’s major marine ecosystems that underpin livelihoods have been degraded or are being used unsustainably.

Ocean acidification may threaten plankton, which is the key to the survival of larger fish.


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04the state of our oceans

If the concentration of atmospheric CO2 continues to increase at the current rate, the oceans will become corrosive to the shells of many marine organisms by the end of this century. How or if marine organisms are able to adapt to this is not yet known.

Ocean acidification may render most regions of the ocean inhospitable to coral reefs. This will have an impact on tourism, food security, shoreline protection and biodiversity.

Commercial overexploitation of the world’s fish stocks is so severe that it has been estimated that up to 13 % of global fisheries have disappeared.

Agricultural practices, coastal tourism, port and harbour developments, damming of rivers, urban development and construction, mining, fisheries, aquaculture and manufacturing, among others, are all sources of marine pollution threatening coastal and marine habitats.

Excessive nutrients from sewage outfalls and agricultural runoff have contributed to the number of low oxygen (hypoxic) areas known as “dead zones”, where most marine life cannot survive, resulting in the collapse of some ecosystems.

There are now close to 500 dead zones covering more than 245,000 km² globally, equivalent to the entire area of the United Kingdom.

Technological change and the emergence of deep sea mining, sand dredging, more intensive fishing and deeper oil and gas drilling increase risks to ocean areas that historically were not under threat.

Coastal systems Coastal systems such as mangroves, salt marshes and seagrass meadows have the ability to absorb carbon at rates up to 50 times those of the same area of tropical forest.

Total carbon deposits in these coastal systems may be up to five times the carbon stored in tropical forests. Between 1980 and 2005 alone, 35,000 square kilometres of mangroves were removed globally.

Between 30% and 35% of the global extent of critical marine habitats such as seagrasses, mangroves and coral reefs are estimated to have been destroyed.

It is estimated that by 2100, unless we drastically change the way we interact with our oceans, more than half of the world’s marine species will be on the brink of extinction.

One of the major problems is that by not respecting how we treat our oceans we are being fools to ourselves – all the toxic waste we dump in the sea and abuse of our sea life comes back to haunt us when it enters our food chain and we eat the results.


The main species living in our oceans

Arthropods (such as horseshoe crabs, sea spiders, lobsters, crabs, shrimp, and barnacles)

•Cephalopods (such as octopi, squid and cuttlefish)

•Cnidarians (such as sea anemones, corals, sea pens,

jellyfish, box jellies, and hydrozoans). Coral reefs are the nurseries of the oceans, they are biodiversity hot spots. On some tropical coral reefs, for example, there can be 1,000

species per square metre•

Echinoderms (such as starfish, brittle stars, sea urchins, sea cucumbers, crinoids and sea daisies)

•Fish•

Marine birds•

Marine invertebrates (such as sponges, worms and molluscs)

•Marine mammals (such as whales, orca, porpoises, sea

otters, dolphins and even polar bears)•

Phytoplankton and marine plants (these provide 50% of our oxygen on Earth and form the basis of our oceans’

food chains – for fish and marine mammals and ultimately human consumption)

•Reptiles (such as sea turtles, marine iguanas, saltwater

crocodile and sea snakes)•

Sharks and rays (such as basking sharks, blue sharks, the great white shark, hammerheads, preying mantas and

stingrays, nurse sharks and whale sharks)•

Zooplankton (such as insect larvae and gastropods).

To find out more visit: www.arkinthesky.org/en/discover/oceans

Whales

Virtually everyone is fascinated by whales ... perhaps because like us – they are mammals.


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These impressive marine mammals roam throughout Earth’s oceans and yet still have the ability to remain in communication with each other, even over vast distances.

Whales belong to a group of marine mammals called cetaceans. Cetaceans are similar to humans in that they breathe air, are warm-blooded and give birth to live young. Others in the group are dolphins and porpoises.

A few whale factsAll whales are either “mysticeti” (that is, baleen whales such as the Humpback whale) or “Odonotoceti” (toothed whales such as the Sperm whale).

•One quarter of the world’s 80 whale and dolphin species belong to the family of beaked whales.

•The Right whales were called “right” because they are slow-moving and originally considered the “right” size for whalers to catch)!

The Sperm whale is the largest of the toothed whales.

•Narwhal is famous for its vast repertoire of sounds (hence its nickname – “the canary of the sea”) and its tusk-like tooth.

•Only 2 populations of Grey whales are still in existence – one of these populations is made up of just 130 individuals.

•The Humpback whale is the whale you are most likely to see when whale watching.

•The Fin whale is the fastest of the large whales.

•The Blue whale is probably the largest mammal to have ever lived on Earth and can reach over 182,000 kg!

•Bowhead whales are known to live for over 100 years.



Dolphins

Scientists have found evidence that dolphins call each other by “name”

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The range of abilities of dolphins never ceases to amaze us. Scientists have found evidence that dolphins call each other by “name” by using a unique whistle to identify each other.

A team of researchers found that when the animals hear their own call played back to them they respond.

Dr Vincent Janik, from the University of St Andrews in Scotland’s Sea Mammal Research Unit, said that dolphins live in a three-dimensional environment, offshore without any kind of landmarks and so they need to stay in touch in order to keep together as a group.

“These animals live in an environment where they need a very efficient system to stay in touch,” said Dr Janik.

“Most of the time they can’t see each other,

they can’t use smell underwater ... and they also don’t tend to hang out in one spot”

To investigate, researchers recorded a group of wild bottlenose dolphins, capturing each animal’s signature sound. They then played these calls back using underwater speakers.

“We played signature whistles of animals in the group, we also played other whistles in their repertoire and then signature whistles of different populations – animals they had never seen in their lives,” explained Dr Janik.

The researchers found that individuals only responded to their own calls. The team concluded that the dolphins were acting like humans: when they hear their name whistled, they whistle back!



Coral

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Despite their importance, coral reefs are one of the

most complex and poorly understood ecosystems in the world. Understanding

the specific causes of the problems facing reefs is an essential

step in protecting these important wildlife

habitats.


Corals are tiny animals called “polyps” that can live on their own but are mainly associated with the reefs they construct; however, these reefs face an uncertain future.

Coral polyps are fascinating, tiny, soft-bodied organisms related to sea anemones and jellyfish. They live in large communities made up of individual polyps that secrete a calcium carbonate substance that as it hardens forms the structure we know as coral reefs.

Polyps can vary in size, colour and shape. They are generally only a few millimetres, although some can be smaller and others much larger. Polyps always have a tiny mouth, which is surrounded by tentacles. The other end of the polyp is framed by a tiny exoskeleton.

Polyps are very sensitive to changes such as ocean temperature, pollution and acidity.

Coral reefs Amazingly, reefs begin when a polyp attaches itself to a rock on the sea floor, then divides into thousands of clones. The polyp “calicles” (limestone skeletons) connect to one another, creating a colony that acts as a single organism.

Several different types of corals can together form enormous colonies creating a coral reef, the largest of which is the Great Barrier Reef off the coast of Australia.

Coral reefs are some of the world’s most diverse ecosystems, sometimes referred to as the “rainforests of the sea”. Occupying less than 1% of the ocean floor, they support about 25% of all marine species.

There are three basic kinds of coral reefs: Fringing reefs grow in shallow waters close to the coast.

Barrier reefs are separated from land by a lagoon, growing parallel to the coast and forming a large and continuous reef.

Atolls are ring-shaped reefs that develop near the sea surface on underwater islands or islands that sink or subside. Some atolls are big enough to be inhabited, e.g. the Maldives.

A variety of shapes and sizes Corals come in a variety of shapes and sizes. There are two main types of coral:

Hard corals: These are made up of the hydrocorals and the stony corals. Both types of coral have hard skeletons made of calcium carbonate. There are two kinds of hydrocorals – fire and lace corals.

Soft corals: These are called soft corals because they do not have hard, rigid permanent skeletons. They sway back and forth with the currents. This group is made up of the gorgonians and the black corals.

Symbiotic life-style The coral polyps live symbiotically with algae that provide them with food. These algae are called zooxanthellae and give coral its colour.

Like their jellyfish and sea anemone relatives, coral polyps have stinging tentacles that they use to catch food. During the day, these tentacles are usually tucked away, out of reach of hungry fish and other marine animals. At night they unfold to catch their prey, mainly plankton.

When stressed the corals expel the algae (zooanthellae) causing the coral to lose both its colour and source of food. Called “coral bleaching,” this can eventually kill the colony. If the coral does not regain algae, the coral polyps eventually die.

Benefits of coral reefs Not only do they support enormous biodiversity, coral reefs are also of immense value to mankind as they act as natural barriers, protecting coastal cities, communities and beaches from the strength of storms, hurricanes, typhoons and even tsunamis.

Coral reefs are an important source of food for local communities and are vital to the world’s fisheries. They provide revenue for local communities as well as national and international fishing fleets. They also make important contributions to local economies as they attract tourists for diving tours, snorkelling, boating trips, the beaches and other activities.

Many corals have evolved chemical defences to protect themselves from predators. Scientists believe these defences may hold the key to new medicines to treat a variety of human diseases such as cancer.To find out more visit: www.arkinthesky.org/en/discover/oceans


Threats to coral

Coral reefs have survived tens of thousands of years of natural change but they are threatened by an increasing array of impacts. Many of the world’s reefs have already been destroyed or severely damaged.

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Climate change and water temperature. Coral is associated with warm waters, but corals cannot survive if the water temperature is too high. Even a small increase in the average temperature can result in coral bleaching.

Ocean acidification endangers coral reefs as it threatens the ability of corals to create their calcium carbonate skeletons and thus slows their growth.

Unsustainable fishing such as overfishing and destructive fishing practices, e.g. bottom trawling and cyanide fishing, blast or dynamite fishing, are all threats to coral.

Pollution from urban and industrial waste, sewage, agrochemicals and oil pollution are all poisoning reefs. Some pollutants, such as sewage and runoff from farming, increase the level of nitrogen in seawater, causing an overgrowth of algae that can swamp the coral, cutting off sunlight.

Increased sedimentation caused by construction can end up on the coral reefs surface; again, cutting off sunlight. The destruction of mangroves that normally trap large amounts of sediment is exacerbating the problem.

Coral mining and dredging activities along with careless tourism are other threats to coral reefs and their habitats.


Fish breathe through gills, usually live in water and are generally cold-blooded (that is, they are “ectothermic”, which means their body temperature adjusts quickly and so they easily adapt to the changing temperature of the water around them).

Even so, very active fish such as tuna, swordfish and some species of shark can heat their bodies above the temperature of the surrounding water.

While most fish breathe through gills, extracting oxygen from the surrounding water, many freshwater fish can also absorb oxygen from the air using a variety of alternative methods.

Fish classificationWith so many diverse fish species it is not surprising that their classification is somewhat complicated. In the simplified version and omitting extinct species, there are three main classifications of fish to be found in Earth’s waters today:

Agnatha (jawless fish) o Subgroup Cyclostomata (lampreys and hagfish)

Chondrichthyes (fish with cartilage) o Subgroup Elasmobranchii (sharks, rays and skates) o Subgroup Holocephali (chimaera – long-tailed fish with an erect spine before the first dorsal fin)

Osteichthyes – (bony fish) includes many well-known species of fish

o Subgroup Actinopterygii (ray- finned fish) o Subgroup Sarcopterygii (fleshy- finned fish)

As you will have noted, species such as shellfish, cuttlefish, starfish, crayfish and jellyfish are

With around 30,000 different species, fish are the most diverse of all vertebrate species (animals that have backbones). As you will discover – diversity is

everything in the fish world.

not included in this list as they are not fish in the true sense of the word.

Fish are found in most of the world’s waters – from oceans to streams and lakes – from shallow waters to the depths of the oceans, with approximately 50% of fish species living in marine oceans and approximately 50% being freshwater fish.

Diversity is everything Diversity is everything in the fish world and body shapes and fins are no exception. Shapes and fins range from the generally recognized as the normal fish shape of the salmon or cod to the exotic seahorse, pufferfish to the gulper deep-sea eel with its enormous jaws.

While most easily recognizable bony fish are covered in ctenoid scales, which have many tiny projections on the edge like the teeth of a comb (this is what clings everywhere when you’re trying to descale a fish), this is not necessarily the case for all fish species. The moray eel, for instance, has smooth skin while sharks and rays have tooth-like scales made of dentine with enamel (just like our teeth).

Although fish generally live in water some fish, particularly coastal fish, live in waterlogged

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environments found in coastal regions and mangroves. Mudskippers live in mudflats and catfish in waterlogged organic leaf detritus.

Fish range in size from the enormous 16 metres long whale shark to the minute 8 millimetres long infantfish.

Fish as foodFish is an important source of food throughout the world. Saltwater fish, such as haddock and cod, are found in our seas and oceans whereas freshwater fish, such as brown trout, carp, perch and grayling, are found in our lakes, rivers and streams. Some fish, such as salmon and sea trout, even live part of their lives in both saltwater (sea water) and freshwater.

In many countries people only survive because they are able to catch and eat fish. In other countries fish are specifically farmed in fish farms to provide food.

Fish under threatCurrently, the IUCN Red List calculates that 985 fish species are either critically threatened with extinction or endangered due mainly to habitat degradation, water pollution, “ocean acidification” and overfishing, including the discarding of unwanted fish.

“Ocean acidification” is the term used to describe the process of ocean water becoming more acidic as a result of absorbing nearly a third of the carbon dioxide released into the atmosphere from human sources. This change in ocean chemistry is affecting marine life, particularly the ability of shellfish, corals and small creatures in the early stages of the food chain to build skeletons or shells.

Overfishing is a major threat to edible fish such as cod and tuna. Fish stocks around the world are getting smaller and smaller. Eventually the fish that are left will not be able to produce enough young to replace current fish levels.


Discarded fish The Revised Common Fisheries Policy which came into force in 2014 bans the fishing practice of discarding unwanted fish back into the sea. Fish are discarded because they are generally too small to sell or the trawler has already caught its limit of that species of fish. As a consequence often half or more of a trawler’s catch is thrown back into the sea and many of these are either injured or are already dead.

But a report published in November 2013 by Fisheries Research has concluded that this ban won’t help protect fish stocks unless it is combined with carefully controlled quotas on total catches as they believe fishermen will still catch the same quantity of fish and any fish unsellable for human consumption will simply be sold on as animal food or for use in agriculture.

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There is a 19th century saying, “The tide never goes out so far but it always comes in again.”

Sea tides are dependable daily phenomena – but their seeming simplicity ends there. c

Tides are due to the interaction of the Sun and the Moon on Earth’s oceans and seas. This interaction causes our seas and oceans (and occasionally rivers) to alternately rise and fall – a reaction that is anything but simple!

Tides originate in the oceans and progress toward the coastlines where they appear as the regular rise and fall of the sea’s surface.

Sir Isaac NewtonIn 1687, Sir Isaac Newton discovered what is called the “Law of Universal Gravitation” (whereby the greater the mass of objects and the closer they are to each other, the greater the gravitational attraction between them*).

This discovery confirmed that relationship between the Earth, Moon and Sun’s individual masses and their distances to each other play critical roles in affecting our tides and that ocean tides are a direct result of this gravitational attraction.

The gravitational attraction between the Earth and the Moon is strongest on that side of the Earth that happens to be facing the Moon. It creates a tidal “bulge” on that side of the Earth, which fortunately results in a counterbalancing “bulge” on the other side of the world.

Because tides on Earth are a direct response to the alignment of the Moon and a lunar day is 24 hours and 50 minutes, coastal areas experience two high and two low tides during every 24 hours and 50 minutes.

Tidal “bulges”You would imagine that all areas on the planet experience two equally proportioned high and low tides every lunar day, but this is not the case. Since the Earth isn’t a perfect sphere and also has large continents hindering the flow of water, tides have established complex and differing patterns within each ocean.

When oceanic tidal “bulges” hit wide continental shores the height of the tides can be magnified. On the other hand, mid-oceanic islands that are not close to major continents generally experience very small tides of 1 metre or less.

The highs and lowsThe shape of bays and estuaries can magnify the intensity of a tide. Funnel-shaped bays in particular can dramatically alter the scale of a tide. A classic example is the Bay of Fundy in Nova Scotia which has the highest tides in the world – over 15 metres high!

Narrow inlets and shallow water tend to disperse incoming tides.

the time of tides

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In the Spring, powerful seasonal river flows in estuaries with strong tidal rivers can severely alter or mask an incoming tide – a potentially dangerous situation.

Strong offshore winds can move water away from coastlines making a low tide seem unusually low. Onshore winds may act to pile up water onto the shoreline making a high tide seem unusually high.

Local weather patterns can affect tides. High-pressure systems can lower sea levels resulting in clear sunny days with exceptionally low tides.

Low-pressure systems that result in cloudy, rainy conditions typically produce tides that are much higher than expected.

To help you surf through the mysteries of tides we’ve put together a list of tidal terms:

High tide When the highest part, or “crest”, of the wave reaches a particular location, a “high tide” occurs.

Low tide A “low tide” is when the lowest part of the wave, or its trough, reaches a particular location.

Tidal range The difference in height between a high tide and low tide is called the “tidal range”.

Neap & Spring tides There are two main tides (not to be confused with normal tides) that are higher or lower than average, they occur twice monthly and are referred to as “Neap” and “Spring” tides.

Spring tides When the Sun, Moon and Earth are in alignment (at the time of a new or full moon), extra-high high tides and extremely low tides are created – these are called “Spring tides” and occur twice a month.

Neap tides One week later, when the Sun, Moon and Earth


Tidal heights

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are at right angles to each other, the solar tide (caused by the gravitational attraction of the Sun) partially cancels out the lunar tide (caused by the gravitational attraction of the Moon) and produces moderate tides referred to as “neap tides”. A neap tide occurs twice a month during the first and last quarter of the Moon.

Perigee tidal impacts Once a month, when the Moon is closest to the Earth (referred to as “perigee”), tide-generating forces are higher than usual, producing above-average ranges in tides.

Apogee tidal impacts About two weeks later, when the Moon is farthest from the Earth (referred to as “apogee”), the lunar tide-generating force is less and the tidal ranges are lower than average.

Perihelion tidal impacts When the Earth is closest to the Sun (referred to as “perihelion”), which occurs around 2 January each year, tidal ranges are greater.

Aphelion tidal impacts Around 2 July, when the Earth is furthest from the

Tides and the Earth, Moon and Sun

Sun (referred to as “aphelion”), tidal differences are less.

Tidal currents These move marine life to and from breeding grounds in seas and estuaries to deeper waters. Tidal currents also circulate nutrients (and pollutants) around the oceans and have an impact on climatic change.

Flood & Ebb currents As the tides rise and fall, they create “flood” and “ebb” currents. The strongest flood and ebb currents usually occur before or near the time of high and low tides.

Flood currents An incoming coastal tide running into bays and estuaries can reach up to several kilometres per hour. This is called a “flood current”.

Ebb currents An outgoing tide is called an “ebb” current.

Slack tides The weakest currents occur between the flood and ebb currents and are called “slack tides”.

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Can you name these sea species?

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You’ll find all the answers in this magazine or at: www.arkinthesky.org/discover/oceans

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Oceans play an important part in our weather systems. We have certainly all heard about the dramatic consequences of some extreme El Niño events on our weather, in particular flooding, drought, bush fires and hurricanes. To help us prepare for these

changes in weather conditions the temperatures, currents and winds in our oceans are constantly monitored by a network of buoys and transmitted daily to researchers and

forecasters around the world.

To understand why El Niño events occur you also need to understand the impact our oceans have on our weather and the major role they play in regulating the weather and climate of our planet.

The “water cycle” The ocean waters are dynamic and their movements influence weather and climate, as well as living conditions on Earth.

The water cycle (also called the hydrologic cycle) is the continuous movement of water on, above and beneath Earth’s surface.

Ocean currents flow in complex patterns and are affected by wind, salinity, water temperature, ocean bottom topography and the Earth’s rotation.

Water evaporates from the ocean and the Earth’s surfaces, rises and cools as it moves higher in the atmosphere. It condenses as rain or snow and then falls to the surface where it collects in lakes, oceans, soil and in underground reservoirs.

Water flows in a circular pattern – clockwise in the Northern Hemisphere and anticlockwise in the Southern Hemisphere.

We have all heard the name El Niño and the dramatic consequences of some extreme El Niño events on our weather.

So why do these happen?

Wind-driven and ocean-current circulations move warm water towards the poles and colder water towards the equator.

Ocean/atmosphere relationshipThe oceans can store much more heat than land, which is why the majority of thermal energy at the Earth’s surface is to be found in our oceans. As a consequence the absorption and movement of energy on Earth is dependent on the ocean/atmosphere relationship.

When air in contact with the ocean is at a different temperature to the sea’s surface, heat transfer takes place. Oceans also absorb and store energy from the Sun and when rain falls, it releases this heat energy into the atmosphere.

The transfer of heat energy occurs as a result of radiation, convection (the transfer of heat caused by the tendency of heat to rise) and conduction (the transmission of heat from a region of higher temperature to a region of lower temperature).

Heat flows from warmer objects to cooler ones, until both reach the same temperature. Because ocean water holds a large amount of heat they have a major effect on our climate.

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El Niño regional impactsWarm episode relationships from December to February

Warm episode relationships from June to August

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Ocean currentsOcean currents play an important role in transferring this heat towards the Earth’s poles. Major currents, such as the northward flowing Gulf Stream, transport tremendous amounts of heat to the poles and contribute to the development of many different weather phenomena.

Seawater that flows in Polar Regions will cool or freeze, becoming saltier and denser and so it tends to sink and result in deep ocean currents.

El Niño eventsAn El Niño occurs when unusually warm ocean temperatures are experienced in the equatorial or tropical Pacific Ocean.

According to the UK Met Office, “The natural variability of our climate is driven in large part by the El Niño Southern Oscillation (ENSO) in the tropical (Equatorial) Pacific Ocean. In the El Niño phase, global temperature tends to rise, whereas in the La Niña phase it tends to fall.”

El Niño was first recognized thousands of years ago by fisherman off the coast of South America with the appearance of unusually warm water in the Pacific Ocean that occurred around Christmas time, which is why they called it the “Christ child” or “Little boy” (El Niño in Spanish).

The extremes of weather conditions that are the result of an El Niño event depend on normal local conditions and are difficult to predict, which is why the temperatures, currents and winds in the equatorial (or tropical) Pacific are constantly monitored by a network of buoys and transmitted daily to researchers and forecasters around the world.

The cycle of El Niño and La Niña in the equatorial (or tropical) Pacific Ocean affects not only global temperatures, but can also drive some dramatic changes in rainfall patterns in different parts of the world.

An El Niño can result in above or below average rainfall, flooding, extremes of temperature, abnormal thunderstorm activity, abnormally dry conditions, Indian monsoon rainfall being diminished or delayed, bush fires and increases or decreases in the number of hurricanes, typhoons and tropical storms.

La Niña eventsEl Niño should not be confused with La Niña, which occurs when unusually cold ocean temperatures are experienced in the equatorial or tropical Pacific Ocean.

La Niña means “Little girl” in Spanish. La Niña is sometimes called “El Viejo” or anti-El Niño, or simply “a cold event” or “a cold episode”.

Major Atlantic El Nino hurricanes

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Portuguese man-of-war

Is it a fish? Is it a jellyfish? Is it an alien? ... No, it’s none of these.

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The Portuguese man-of-war is actually a “siphonophore” – that is it is not one individual animal but a colony of genetically identical individuals called “zooids”.

Zooids are so interdependent on each other that they can’t survive on their own and together they form integrated groups (known as polyps) that specialize in specific organ functions – some are dedicated to digestion, others reproduction and still others, as in the case of the Portuguese man-of-war, to creating tendrils that can trail up to 50 metres below the surface of the ocean!

Poisonous tendrilsThe Portuguese man-of-war’s tendrils are highly poisonous and can kill young fish and small shrimp or tiny crustaceans that it captures and immobilizes to digest.

The tendrils contain miniscule hollow harpoons called “nematocysts” that act like hypodermic

needles injecting its venom into whatever prey they attack.

Gas-filled bladderIts name comes from its gas-filled bladder that floats above water and is thought to resemble an 18th century Portuguese warship.

This bladder is full of carbon monoxide and can shrink in an instant if the siphonophore should be under attack from an unexpected predator such as a sea turtle.

Its floating bladder allows the siphonophore to float wherever the wind takes it – even if it is straight into the arms of an unwary swimmer or to ultimately founder on a beach.

Its vibrant colouring encourages closer inspection – but take care – being a relative of the jellyfish, the Portuguese man-of-war is famous for the extreme pain it inflicts on anyone it stings!


Sharks

Mankind is more likely to kill a shark than a shark is to kill man ... according to WWF, more than 100 million sharks are killed each year.

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Sharks are among the most ancient of fish, having developed about 64 million years ago. They belong to a special category called “Elasmobranchs”, which means their body is made out of cartilage instead of bone. This group also includes rays, sawfish and skates.

Sharks can be found in all types of ocean waters – from deep to coastal, from icy to tropical. A few sharks even swim up rivers. The shape of a shark’s body provides clues as to its habitat and way of life.

Sharks breathe through their gills, taking in oxygen from the water. Most sharks live in the open seas and will suffocate if they cannot move forward in the water because they need to force seawater through their open mouths and over their gills to breathe.

Some sharks live on the sea floor where the current is strong enough to move water over their gills; others, with well-developed gill muscles, breathe by pumping water over their gills.

Sharks have relatively large, complex brains and communicate with each other through their body language.

They are omnivorous – they will eat anything, both meat and vegetation, although the largest shark of all, the Whale shark, feeds mainly on plankton.

Sharks have excellent eyesight and have three senses that we do not have. The lateral line, pit organs and Lorenzini are senses that have recently been discovered and play an important role in how the shark functions.

The dark spots on the shark’s snout and lower jaw are pores that mark the opening of the ampullae of Lorenzini, jelly-filled canals that allow the shark to pick up weak electrical fields. They use this sense to find food.

A shark’s teeth aren’t attached and are continually being replaced – it may lose between 12,000 and 30,000 teeth during its lifetime.



88% of the oceans’ surfaces contain plastic debris!High concentrations of floating plastic debris have been reported in remote areas of the ocean, increasing concern about the accumulation of plastic litter on the ocean surface and the potential harm to fish and other wildlife.

Ocean studyA study that draws on results from an ocean voyage around the world in 2010, the Malaspina Expedition, shows that up to 88% of the oceans’ surfaces contain plastic debris.

The study estimates only floating debris and not plastic that may be below the ocean surface.

Ocean gyresThe research showed plastic concentrations were highest in the convergence zones of each of the five subtropical gyres with comparable density (gyres are the circular patterns of currents in an ocean basin).

Where these gyres come together they make huge “conveyor belts”, bringing trash from shores onto the surface of the open ocean.

Lasting 100s of yearsAs well as the well-known accumulation of plastic rubbish in the North Pacific, the experts have proven the existence of similar accumulations in the centre of the North Atlantic, the South Pacific, the South Atlantic and the Indian Oceans.

“Ocean currents carry plastic objects which split into smaller and smaller fragments due to solar radiation,” said Andrés Cózar, author of the study at the University of Cadiz in Spain. “Those little pieces of plastic, known as microplastics, can last hundreds of years.”

These small fragments often accumulate contaminants that can be passed on to organisms that eat them.

The major residues found were polyethylene and polypropylene, polymers used in the manufacture of everyday products like bags, food and beverage containers, home utensils and toys, among others.

7,000 to 35,000 tons!On the basis of samples collected on the Malaspina Expedition, researchers estimated the total amount of floating plastic debris in the open ocean at 7,000 to 35,000 tons, with the greatest concentration in the North Pacific, which represents 33% to 35% of the total.

The amount is much smaller than expected and the study suggests that surface waters are not the final destination for buoyant plastic debris in the oceans.

“Our estimates indicate that the tens of thousands of plastic tons floating on the surface waters could represent only 1% of the plastic pollution in the oceans,” Cózar said.

The quantity of plastic floating in the oceans, its final destination and impact is still unknown.

Some good newsOcean Cleanup has created The Ocean Cleanup Array to clean up plastic debris. If the proposed system is deployed, in 10 years it could remove half of the plastic in the area which has become known as the Great Pacific Garbage Patch.

plastic in our oceans

For more: www.arkinthesky.org/en/discover/innovations-of-man

We all know that water finds its own level, so you could be forgiven if you thought that our oceans and seas are like water in a full bathtub

– but our oceans and seas are anything but smooth and level.c

The surface of our oceans and seas are anything but flat – they are as undulating as the rolling countryside we find on land and have been like this for thousands of years. But these levels are beginning to change.

Melting ice sheetsOne of the most important causes of these changes is melting ice sheets. Ice sheets are so huge that their gravity “sucks” water inwards towards their edges so that when they melt this causes the sea levels around them to drop.

There are three main hypothesis:

•If Greenland’s ice sheet were to disappear completely, it is estimated that sea levels around northern Scotland would drop by more than 3 metres and around Iceland by more than 10 metres; whereas around most of Europe’s coasts it would rise to above-average levels. Other parts of the world would experience above-average rises in sea levels, except for South America where the rise would be a massive 10 metres.

•If the West Antarctic’s ice sheet were to melt it is estimated that sea levels near Antarctica would fall; around the southern tip of South

America there would be a slight rise in sea levels; but elsewhere, sea levels would increase by between 3 and 6 metres except for the east coast of the USA, where they would reach at least 25% above average.

•But one melting ice sheet can change the rate at which another ice sheet melts. If climate change causes sea levels around Greenland to rise, West Antarctic’s ice sheet would melt more quickly, so it is important to keep precise measurements about melting ice sheets and changes in sea levels.

As ice sheets in the Antarctic (in the southern hemisphere) and in Greenland (in the northern hemisphere) are melting, more water is being added to our seas and oceans – and it has to go somewhere.

Greenland’s ice sheet is currently melting faster than West Antarctic’s ice sheet. Recent studies suggest that Greenland’s ice sheet will eventually disappear but it could take several centuries for this to happen – although it is difficult to be precise because the Earth has never before warmed at its current rate.

It is even more difficult to accurately calculate the melting of West Antarctic’s ice sheet



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because it is sitting on rock that is several hundred metres below sea level. This fact alone could slow down the speed at which it melts.

The researchThe original research comes from Dr Robert Woodward who was a physicist working on the 1888 US Geological Survey. He realized that large landmasses and ice sheets on Earth exert a strong gravitational pull on surrounding water – “sucking” the surrounding water towards their edges

He deduced that this gravitational pull reduces as the ice melts, thereby causing the sea to recede. He worked out a way to calculate the changes in water levels caused by this.

In the mid-1990s, the TOPEX/Poseidon satellite confirmed Dr Woodward’s findings and was able to measure sea levels to an unprecedented accuracy.

“Rapid rebound” is another phenomenon that affects sea levels. The vast ice sheets that formed originally in North America and Eurasia were so heavy that the pliable Earth’s crust below them sank by as much as 500 metres.

When the ice began melting 20,000 years ago this land started to rebound, slowly springing

back into place. Some of these areas are still rising or sinking even today.

Altering Earth’s balanceIn 2001, J Mitrovica and his team at Harvard University showed that if an ice sheet melts the subsequent change in weight distribution also alters Earth’s balance by shifting the axis on which the Earth rotates, which in turn adds extra bumps or dips to sea levels.

After measuring the position of the North Pole from 2005 to 2013, Jianli Chen of the University of Texas, Austin and his colleagues have shown that the North Pole suddenly began moving eastwards in 2005 – moving 1.2 metres to date. “Ice melting and sea level changes can explain 90% of this shift,” says Chen.

Warmer oceansAccording to the Intergovernmental Panel on Climate Change, changes in wind patterns over the Tropical Pacific are playing key roles in driving up sea levels – piling up debris in the Western Pacific and increasing global sea level rise due to expanding warmer oceans and melting ice sheets.

blogit Highlights of some of your questions and answers. For the complete answers to these and lots of other questions visit: www.arkinthesky.org/en/blogit/blog

Jamie McPherson, Scotland asks: They say that the oceans are a largely

untapped source of food and other possible resources, is this true?

According to UNESCO, our oceans make up over 90% of habitable space on our planet and 50-80% of all life on Earth is to be found in them. So it is not surprising that they are probably the most under explored and scientifically understood area of our planet. This is why we must do our best to ensure their survival and that of all the animals, plants and the fragile ecosystem that exists there.

There have been fascinating recent discoveries regarding both marine worms and whales.

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Marine wormsAll life on Earth is said to have had its origins in the sea. According to Dr. Franck Zal, founder of Hemarina Discovery (a marine biotechnology company based in Morlaix, France), he has created artificial blood that is compatible with all blood groups. This blood is built on the haemoglobin of simple marine worms that are found on beaches and coasts around the world! As strange as it may seem, these worms’ haemoglobin could save millions of people’s lives because its oxygenating power is 50 times larger than ours. This could be a fantastic discovery since there are often many problems related to finding sufficient compatible blood-type transfusion sources especially in emergency situations.

Whales

Whales are generally very large so it is not surprising that when they excrete they excrete a lot and they do so near the surface of the ocean. Their excreta release huge amounts of nutrients into the ocean. The ocean’s surface is also where most of the Sun’s rays and oxygen are on Earth.

Living in our oceans are microscopic plants called “phytoplankton”. These phytoplankton plants produce 50% of the oxygen we breathe and form the basis of our oceans’ food chains driving the ecosystems of our oceans. When phytoplankton have used up all the nutrients in the water around them they start to die off – which is where whale pooh comes in – whale excrement is an excellent fertilizer and so helps the phytoplankton to survive and continue to propel the ecosystems in our oceans and oxygen for us.

People used to think that whales were our competitors because they consumed the same fish that we eat. Now we know they are our allies by recycling nutrients, helping to sustain our oceans.

See: http://www.arkinthesky.org/en/discover/oceans

Concerned, Truro, UK asks: Elephants are wonderful creatures but

people that live near them in the wild say that they destroy huge areas of cultivated

land and even homes and gardens.

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19-22 SEPTEMBER Beachwatch Big WeekendBeachwatch Big Weekend is a national event held annually by the Marine Conservation Society which involves thousands of volunteers cleaning up and recording the rubbish they find on beaches all around the UK.

16 OCTOBER World Food Day The aim of World Food Day is to increase awareness of world hunger and to encourage action. Many different events round the world raise awareness of problems in food supply and distribution and raise money to support projects to aid in the cultivation of food plants and the distribution of food.

Is this true and why should we try to protect animals that do so much damage?

Did you know that the elephant is a key element in maintaining our flourishing tropical forests? The tropical rainforests of Africa and Asia play a crucial role in keeping our planet healthy. They moderate our climate, absorb the carbon we produce … and act as a major source of atmospheric moisture.

Because elephants eat huge amounts of seeds and disperse them throughout the forest (complete with a package of excellent fertilizer), plants and trees continue to propagate naturally – keeping our eco-system in balance – so the whole planet benefits.

There are several reasons why we should protect our World’s elephants, not least because they are the largest living animals on Earth and both the African and Indian elephant species are seriously endangered due mainly to habitat degradation and poachers hunting them for their ivory tusks.

Although the IUCN Red List of Threatened Species announced in 2013 that key states had committed to urgent measures to halt the illegal trade and secure elephant populations across Africa but the gory slaughtering of elephants continues.

As with most problems on Earth, the elephant’s habitat degradation is caused by mankind. Mankind continues to expand and expect from Earth more than Earth’s diminishing resources are able to provide. In order to provide homes and food for mankind we are occupying more and more of Earth and in the process destroying and taking over many places that are the natural environments and food sources of many other species such as elephants.

See: http://www.arkinthesky.org/en/discover/animals

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22 SEPTEMBER World Rhino Day This event was established to raise the profile of rhino conservation and to encourage awareness of the issues facing all five rhino species today.

4 OCTOBER World Animal Day The aim of World Animal Day is to celebrate animal life in all its forms as well as humankind’s relationship with the animal kingdom. Established in 1931 at a convention of ecologists it has now spread around the world, celebrating not just endangered and rare species, but all kinds of animal life.

29 NOV–7 DEC National Tree Week National Tree Week is the UK’s largest tree celebration – annually launching the start of the winter tree planting season. This is a great chance for communities to do something positive for their local treescape.

11 DECEMBER International Mountain Day International Mountain Day is intended to create awareness about the importance of mountains to life and highlight the opportunities and constraints in mountain development in order to build partnerships that will generate positive change to the world’s mountains and highlands.


For all these and more visit: www.arkinthesky.org/en/events

who’s stealing our ozone?

For more visit: www.arkinthesky.org/en/discover/climate_change

Scientists and regulators want to know where the excess of carbon tetrachloride recently found in our

atmosphere is coming from ... do you know?

On 20 August 2014, NASA announced that it had detected an unexplained quantity of carbon tetrachloride (CC14) in our atmosphere. This chemical is a major destroyer of our ozone layer and its usage had been phased out under the Montreal Protocol of 1987. Protocol member countries announced no new CC14 emissions between 2007 and 2012.

But the recent NASA study shows that global emissions of this pollutant are currently averaging 39,000 tonnes per year, or about 30% of the maximum volume ever recorded before the entry into force of the Montreal Protocol.

“We should not see any CC14”, said Qing Liang, a scientist at the NASA Goddard Space Flight Center in Maryland and lead author of the research. “It is clear that we are in the presence of unidentified industrial leaks of either significant emissions of contaminated sites or unknown sources of CCl4,” he added.

For a long time now scientists have wondered why the observed levels of carbon tetrachloride (CCl4) in our atmosphere are decreasing more slowly than anticipated.

Scientists and regulators want to know where this CC14 is coming from. It had accounted for approximately 11% of the chlorine decrease in the ozone layer in 2008.

According to scientists, without any emission of CCl4 being reported between 2007 and 2012, atmospheric concentrations of this chemical agent should have dropped by 4% per year, although observations from the ground have shown a decrease of only 1% each year.

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ark in the sky vol 2 no 2

Documents

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