SCUBA Travel News

Human activity in the deep sea is extending ever deeper, with recent research showing that this environment is more sensitive to human and natural impacts than previously thought.

Some deep-water fish stocks have collapsed and fishing methods such as bottom trawling have raised international concern over the habitat damage they cause. It is likely that in its current form, deep-sea fishing is unsustainable.

Diminishing reserves of hydrocarbons in shallow water are pushing exploration and production into deeper waters, which may cause damage to little known deep-sea habitats.

The deep sea is also proposed as an environment where carbon dioxide could be stored to minimise the effect of its release into the atmosphere. At the same time, rising atmospheric carbon dioxide levels may be altering the chemical equilibrium of the global ocean by lowering pH.

Many countries are now beginning to designate some deep-sea habitats as marine protected areas in measures to reduce the damage caused by fishing and other human activities.

A new review examines these issues in deep-sea conservation and discusses the conservation status and the designation of protected areas. The enforcement of protected areas using satellite tracking of vessels is discussed and applied to an internationally agreed deep-water conservation area, which aims to protect cold-water coral habitats on the Darwin Mounds in the north east Atlantic Ocean.

Journal Reference: Biological Conservation (2007), doi:10.1016/j.biocon.2007.05.011

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Labels: environment, marine biology

Table coral has a short, stout stem attached by a spreading base. Branches arise from the top of the stem and spread in a horizontal rather than a vertical direction, often fusing together. The closely set and interlocking branches form a roughly circular plate sometimes two or three metres in diameter.

Acropora species are among the fastest growing corals, with upward growth between 10 and 20 cm per year. This is achieved through their porous skeleton and the branched habit that will re-establish themselves readily when damaged.

In the Caribbean, Acropora colonies are brown or yellowish in colour, often with white tips. In the Indo-Pacific, though, they are among the most brightly coloured corals on the reef. Acropora is an important reef-building coral and often dominates shallow areas. It provides shelter for a variety of small fishes and other animals.

Table corals are the most vulnerable to storm damage. Their broad, flat top supported by a narrow stalk makes them more susceptable to strong wave forces than bushy or mounded corals. However, severe storms, by themselves, would do not pose a large threat to reefs. Young colonies do not form tables and the Acropora corals grow and mature quickly.

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Labels: coral, marine biology

On Midsummers Day in 1919, a German Admiral ordered the German High Seas Fleet to be scuttled. Seventy-four German ships had been anchored at the Orkney Islands of Scotland. They were sunk to prevent them being divided up amongst the allies. Many of the ships were recovered for salvage; but those remaining submerged have helped make Scapa Flow into one of the most popular dive sites in Europe.

Lawson Wood's latest book is a comprehensive guide to diving Scapa Flow. The book begins with an introduction to the Orkneys and a history of the German High Seas Fleet. It goes on to cover travelling to, and staying in, Scapa. The rest of the book is a guide to the diving

It is a very extensive guide covering 75 wrecks and 9 reefs. Wood gives the history of each wreck and has plenty of photographs of the dives and the ships. He also provides sea-bed scans of the wrecks and detailed descriptions of each dive site. For each site there is a key points box with a summary of vital information such as location, depth, access and diving experience required.

Many divers assume that you must be extremely experienced to dive Scapa Flow, but the book makes plain that even novice divers can enjoy a good diving holiday there. All of the Motor Torpedo Boats and Blockships are in less than 18 m (60 ft) with many in less than 9 m (30 ft). Lawson Wood rates these as "quite possibly some of the best shallow shipwrecks in the world".

If you are considering going to Scapa Flow then this book is a must. I would buy it well in advance to help you prepare for the trip, deciding where to dive and what equipment to take. It is a great diving guide which is a blend of detailed diving information, wreck history and local information.

About the Author
Lawson Wood has written more than 40 historical and diving guides, including the successful Shipwrecks of the Cayman Islands. He is a founding member of the Marine Conservation Society and founder of the St.Abbs and Eyemouth Voluntary Marine Nature Reserve in Scotland. He made photographic history by becoming a Fellow of the Royal Photographic Society and Fellow of the British Institute of Professional Photographers solely for underwater photography. He is also a Fellow of the Royal Geographical Society.

Review by Andrew Reay-Robinson

The Scapa Flow Dive Guide is available from Aquapress, Amazon and all good bookshops.



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Labels: books, dive destination, UK, wrecks

Fish use the threat of punishment to keep would-be jumpers in the mating queue firmly in line and the social order stable, a new study led has found.

Studying small goby fish at Lizard Island on Australia's Great Barrier Reef, Dr Marian Wong and colleagues have shown the threat of expulsion from the group acts as a powerful deterrent to keep subordinate fish from challenging those more dominant than themselves.

In fact the subordinate fish deliberately diet - or starve themselves - in order to remain smaller than their superiors and so present no threat that might lead to their being cast out, and perishing as a result.

"Many animals have social queues in which the smaller members wait their turn before they can mate. We wanted to find out how they maintain stability in a situation where you'd expect there would be a lot of competition," says Dr Wong.

In the case of the gobies, only the top male and top female mate, and all the other females have to wait their turn in a queue based on their size - the fishy equivalent of the barnyard pecking order.

Dr Wong found that each fish has a size difference of about 5 per cent from the one above and the one below it in the queue. If the difference in size decreases below this threshold, a challenge is on as the junior fish tries to jump the mating queue - and the superior one responds by trying to drive it out of the group.

Her fascinating discovery is that, in order to avoid constant fights and keep the social order stable, the fish seem to accept the threat of punishment - and adjust their own size in order to avoid presenting a challenge to the one above them.

"Social hierarchies are very stable in these fish and in practice challenges and expulsions are extremely rare - probably because expulsion from the group and the coral reef it occupies means almost certain death to the loser.

"It is clear the fish accept the threat of punishment and co-operate as a way of maintaining their social order - and that's not so very different to how humans and other animals behave."

Dr Wong said that experimentally it has always proved extremely difficult to demonstrate how higher animals, such as apes, use punishment to control subordinates and discourage anti-social activity because of the difficulty in observing and interpreting their behaviour.

In the case of the gobies the effect is much more apparent because they seek to maintain a particular size ratio relative to the fish above them in the queue, in order not to provoke a conflict.

"The gobies have shed new light on our understanding of how social stability is maintained in animals," she says.

The paper entitled "The threat of punishment enforces peaceful cooperation and stabilizes queues in a coral-reef fish" was co-authored with Dr Philip Munday and Professor Geoff Jones of CoECRS and Dr Peter Buston of the Biological Station of Doñana, Spain. It appears in Proceedings of the Royal Society B, 274.

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Labels: environment, fish, marine biology, research, sealife