Archive for the 'Pacific Ocean' Category

Extensive coral bleaching is destroying reefs

According to the National Oceanic and Atmospheric Administration (NOAA) of the U.S., the longest coral bleaching ever is occurring in the tropical seas. The on-going, especially strong El Niño is prolonging the event, which started in 2014 and which is likely to lead to a wide-spread die-off of reef corals around the world. The scientists of NOAA expect the bleaching to continue in 2016 and 2017. So far, the Caribbean, Indian Ocean and Pacific Ocean have been affected.

The current bleaching is a serious environmental accident not only for all of us fascinated by the oceans, but especially for those 500 million people whose survival depends on the reefs. Fish species important for human consumption live in the coral communities. In addition to provision of food, the reefs also protect the islands and coastal areas from erosion and other damage caused by powerful waves.

Partly bleached coral colony in Saint Lucia. Copyright (c) 2016 Erkki Siirila.

Partly bleached coral colony in Saint Lucia. Copyright (c) 2016 Erkki Siirila.

Coral reefs are also key habitats for marine biodiversity and, related to that, increasingly important for underwater tourism. NOAA estimates the positive annual contribution of coral reefs to world economies to be about 30,000 million US dollars.

When corals get stressed by elevated seawater temperatures, they expel their zooxanthellae, the microscopic algae living in their tissues. As the pigment is in the algae, the corals lose their typical color. Bleaching is a serious occurrence, because without their symbiotic zooxanthellae the corals are starving as the microscopic algae are a significant food source. The bleached corals also become attacked by diseases more easily than before.

In case the average water temperature continues at levels higher than normal for several days, the corals can not recover their symbiotic algae and may die. When the colonies die, erosion starts eating reef structures away. A high percentage of the coral area may be lost for ever if a new bleaching hits the reef within a few years, i.e. when there has been too little time for recovery. As in many cases there are also other environmental stress factors (overfishing, sediment runoff, etc.) present, in today’s world, complete recovery is often impossible.

The first serious global bleaching in history occurred in 1998. The second one occurred in 2010. Like in the current third one, the El Niño / La Niña phenomenon is seen as the main underlying course (via elevated mean sea water temperatures). Global climate change is considered as a significative contributing factor behind the exceptionally strong El Niño and La Niña weather changes.

Carbon sink and diversity oasis – Kelp forests are abundant in the coastal waters of all continents

Text and photos (c) 2013 Erkki “Eric” Siirila, copyright & all rights reserved. 

Orange garibaldis, the “official” fish of California, are the first thing I see while entering the undersea kelp jungle of Santa Catalina Island outside Los Angeles. In front of me 50-60-meter long stalks of Macrocystis pyrifera rise from the depth of 20 meters to the surface. They get their buoyancy from gas filled bladders called pneumatocysts. When a diver explores the forest formed by the biggest kelp species in the world, not only the size amazes. Also the growth speed, which in the favorable conditions of southern California may reach 45-50 cm in 24 hours, seems unbelievable.

Diving in a kelp forest is an unforgettable experience.

Diving in kelp forests provides unforgettable experiences.

Even though most kelp areas in California are protected, some others are being utilized for kelp harvesting. Harvesting takes place also in the kelp beds of Baja California, Mexico. Algin, the chemical extracted, is used for getting the right smoothness and thickness, when chemical, cosmetic, pharmaceutical and food processing industries make products for you.

A garibaldi in the waters of Santa Catalina.

A garibaldi in the waters of Santa Catalina.

Charles Darwin highlighted the biodiversity of Macrocystis habitats in the following words: “If in any country a forest was destroyed, I do not believe nearly so many species of animals would perish as would from the destruction of kelp.” In spite of being a statement before the ultra high diversity of the tropical rains forests was known to scientists, the comment still indicates something very basic about the importance of the kelp communities.

Gas-filled pneumatocysts give the kelp stalks buoyancy.

Gas-filled pneumatocysts give the kelp stalks buoyancy.

After the dive, together with diver colleagues we summarize our underwater experiences: the peak moments included encounters with a spiny lobster, horn shark and hawksbill turtle. From the shore I see an American blue heron searching for food on top of the floating kelp. Around the Macrocystis communities I also observe harbor seals and California sea lions. In the undersea jungles of Southern California at least 750 species of fish and invertebrates are known to live. A single kelp stalk may be the home to half a million critters.

Holdfasts anchor the kelp to the sea bottom.

Holdfasts anchor the kelp to the sea bottom.

The same kind of examples from the ocean´s forests are being told around the world. So it is no wonder that the environmental organization Oceana has started to defend the kelp beds, which are found close to shore in regions where the waters are cool – each continent, except the Antarctic, has thousands of kilometers of coast where kelp is an important part of undersea nature (see Kelp forest distribution map). In spite of this, internationally there is little environmental legislation protecting these undersea habitats. Of course all the underwater forests are not as mighty as those built by Macrocystis. In Europe, the kelp communities are formed by Laminaria species, which are common in Norway, to give one example. There they reach a height of two to five meters.

My dive continues with photography of sea urchins, which can be found under rocks at daytime. The urchins are the main enemy of Macrocystis. They eat and destroy Macrocystis´ holdfasts, the “roots” of the giant kelp. In the Santa Catalina waters there are only few urchins. In consequence, the kelp forest looks healthy. When I see a 60-centimeter California sheephead in the viewfinder, I feel grateful to it. The urchins are part of its diet. The fish, which regularly approaches divers and gives the impression of being intelligent, is well known to the Catalina visitors. This exceptionally big individual is easily recognizable and has gotten the name Oscar.

California sheephead keep the sea urchin populations under control.

California sheephead is a fish species which controls the sea urchin populations.

Like Oscar also Californian divers have supported the survival of kelp by removing sea urchins from key bottom areas. The urchin numbers had grown much higher than normal. This lack of balance had mostly resulted from the hunting and overfishing of their natural enemies. In addition to urchin control, in California techniques have been developed to help young and drifting kelp attach to the sea floor. The support actions have resulted in the return of kelp to areas where Macrocystis had disappeared.  For Santa Catalina, healthy kelp forests have become a major attraction which draws thousands of tourists to the island every year.

In Monterey I photograph the graceful sea otters. Here the good news is that the otter population of central and northern California, which was practically destroyed by fur hunters, has significantly grown. In 2013 an estimated 3,000 sea otters live in the region. The animal prays on sea urchins and, when abundant, keeps their numbers at an environmentally sound level.

When sea urchin populations grow in an uncontrolled manner, they can destroy entire kelp forests.

When sea urchin populations grow in an uncontrolled manner, they can destroy Macrocystis forests.

The value of the sea otters and kelp forests off the Pacific coast of North America got a new recognition some time ago. In the October 2012 issue of Frontiers in Ecology and the Environment, Christopher C Wilmers, James A Estes, Matthew Edwards, Kristin L Laidre, and Brenda Konar presented a study which covers the Macrocystis-dominated kelp forests from Vancouver Island to the western edge of Alaska´s Aleutian Islands.

Sea otters feed on sea urchins and can be extremely useful to kelp forest wellbeing.

Sea otters feed on sea urchins and support the survival of kelp communities.

The main conclusions include that in areas where the otters are abundant and at their natural levels, they suppress the sea urchin populations significantly, i.e. so much that the kelp forests flourish. Every year the additional kelp is estimated to capture as much carbon dioxide from the atmosphere as the CO2 production of three to six million passenger cars in 12 months. In ideal conditions, the kelp forests’ capacity to store carbon equals that of a tropical rain forest of the same size.  Thus the kelp forests (especially those dominated by Macrocystis) are an important carbon sink slowing down climate change and global warming.

Alarming coral death on South-East Asian reefs

“It is certainly the worst coral die-off we have seen since 1998. It may prove to be the worst such event known to science,” says Dr. Andrew Baird, an Australian coral reef specialist in an interview by published on 18 October, 2010.

Dr. Baird estimates that approximately 80% of Acropora coral colonies and 50% of colonies by other species have died during the past six months on the bleached coral reefs in the Indian and Pacific Oceans.

Healthy-looking and bleached coral side by side. Photo (c) 2010 Erkki Siirila.

The reefs are numerous: the mass bleaching affects an area which extends from the Seychelles to Sulawesi and the Philippines. Included are reefs in Sri Lanka, Burma, Thailand, Malaysia, Singapore, and Indonesia.  The most diverse reefs of the world are found in the so-called “Coral Triangle” which is within the affected area.

In the Underwatertimes article Dr Baird comments the seriousness of the situation by stating that the live percentage coral cover on the reefs could drop from 50% to about 10% (these are average values).  The recovery, if it ever occurs, will take years.  Fisheries and tourism in the affected coastal and island nations will suffer: the livelihoods of millions of people are likely to be hampered.

The bleaching is being caused by elevated mean seawater temperatures which result in the loss of symbiotic microalgae from the coral tissues. As the pigments are in the algae, the coral colony turns white. When the seawater temperature stays higher than normal for weeks, the bleached coral colonies often die – for nutrition the coral depends on the algae.

The warming of seawater to levels which are higher than normal is related to the planet-wide effects of the periodic El Niño and La Niña weather disturbances, which in turn seem to be getting more extreme with global climate change.

In non-scientific terms the recent events in South-East Asia could perhaps be summarised by stating that “the rainforests of the sea are dying”.  People who have seen a healthy coral reef might also use the expression “a very sad and serious ecological disaster is taking place”.

Coral builds impressive living structures in the tropical oceans. Climate change, seawater warming and coral bleaching may kill these underwater cities. Photo from Hurghada,Egypt, copyright (c) 2010 Erkki Siirila.

Good news from the Californian kelp forests

At the beginning of May 2010 California’s underwater state park system in the U.S. was expanded. As a result, well-known north central coastal areas like Point Reyes Headlands, Bodega Head, the Farallon Islands, and Fitzgerald Marine Reserve are now more professionally protected than in the past. The measure is part of a new conservation regime, in which the state is creating a series of marine protected areas. They stretch from Point Arena to Pigeon Point.
The final result will be well-protected marine parks which are part of a statewide network. One of the key concepts is multiple use: new protected areas will not only restore sea life and habitats but also leave nearly 90 percent of the coast open for fishermen. The rebuilding of fisheries is included in the goals.

The giant kelp (Macrocystis pyrifera) seen in the background is the fastest growing plant on Earth.It grows more than 60 cm in length in 24 hours.Kelp is harvested in order to obtain alginic acid,an important ingredient of beer,icecream and cosmetic products. In the past coastal wastewaters led to population explosions of sea urchins.This harmed the kelp forests as sea urchins eat the holdfasts which anchor the kelp to the bottom. Photo from Santa Catalina Island, California, (c)2010 Erkki Siirila.

Kelp forests, canyons and reefs, where fish and shellfish feed and breed, are habitats of emphasis of the ocean conservation plan being applied. In many cases, the new sanctuaries, in which these habitats are located, are close to land-based parks. This facilitates their use for recreation and education.
Marine Life Protection Act (MLPA) requires the California state to develop a science-based system of marine protected areas. California is the first state in the U.S. to have this kind of comprehensive resource management plan. The latest implementation phases are important steps towards full statewide implementation by 2011. Local conservationists, divers, surfers, scientists, fishermen and business leaders take part in the process.
At the February 2010 Conference of American Association for the Advancement of Sciences several new marine protection studies were released. They confirmed the effectiveness of marine parks, mentioning success stories from the Channel Islands of California and the Great Barrier Reef of Australia. The studies show that ocean habitat protection benefits both fish and fishermen.
The new marine protected areas of California will be monitored by professionals.  Scientists will observe the ecological developments as part of the most ambitious study ever done of California’s coastal waters.  A great deal of work will be carried out underwater.

Tsunami hits Juan Fernández archipelago in Chile

The powerful earthquake which hit Chile on 27 February, 2010, resulted in a tsunami.  Chilean coastal towns south of the capital Santiago suffered. In several communities the devastation was nearly complete.

The tsunami resulted in serious damage and lost lives also in the Juan Fernández archipelago, the home of Robinson Crusoe.  Eyewitness reports tell the megawaves caused destruction in places located 15 metres above the high-tide level. (Commonly tsunamis behave more like sudden and extreme high tides than normal waves.)

Sad events like these emphasise the importance of sound management of the coastal zone.  Wise people are proactive, while the less wise are reactive and pay a higher price: a well known fact in coastal risk management is that prevention costs less than reparation.

The wise never forget the power of the sea. Photo (c) 2010 Erkki Siirila.

In Chile, the government is aware that earthquakes are part of life. The Chileans cannot be critised for the lack of preparedness.

In any case, the first pictures taken after the earthquake in Juan Fernández in the Pacific Ocean show the power of tsunamis.  Lessons in coastal management can be learned by looking at the photos.

Wide construction-free zones on oceanic shores are one solution. Improving the tsunami warning systems would be another. Also better construction practices, which take into consideration the forces of nature, help minimise the damage.

Most of the people who suffered from the tsunami in Chile were not warned because of misunderstandings between authorities and hesitation during the crucial moments. Radio news had even transmitted messages telling there was no tsunami risk.

It is also possible that many people did not remember the simple safety rule the Chilean authorities use when they inform of precautionary measures: If you cannot keep your balance while experiencing an earthquake on the coast, the earthquake is so strong that it can produce a tsunami.  You should immediately escape.

The link to the first Chilean tsunami images, which are from Juan Fernández, is here:

Tsunami damage in the Juan Fernández archipelago, Chile  (Sorry, the photographer has removed the pictures from Flickr. This direct link is not working any more.)

Alarming coral news from Australia

Science presented in January 2009 alarming news on the challenges facing coral reefs.  In a scientific article Glenn De’ath, Janice M. Lough and Katharina E. Fabricius summarised the evidence from 69 reefs in the Great Barrier Reef of Australia.  According to that study reef-building corals are under increasing physiological pressure from a changing climate and ocean absorption of increasing atmospheric CO2.

The calcification rate in the studied areas had diminished by 14.2% since 1990.  This kind of drop in calcification is “unprecedented in at least the past 400 years”.

The authors suggest that temperature stress and declining saturation state of seawater aragonite are diminishing the ability of the Great Barrier Reef corals to deposit calcium carbonate.  If this is really happening, the physical structure of the reefs is in danger to erode away and the whole coral reef ecosystem can be considered endangered.

Professor Ove Hoegh-Guldberg from the University of Queensland has presented similar alarming indications of the threats to coral reefs.  He highlighted the dangers of  the increasing atmospheric CO2 levels to coral reefs at the U.S. Center, Copenhagen, in December 2009.  This is the link to the video summary of his presentation:


Coral reef calcification: hope and controversy

In a controversial article in the journal Geophysical Research Letters Australian scientists state that coral reefs could expand in size by more than 30% in response to ocean warming related to climate change.

The research results published five years ago suggest that coral reef calcification rates would not be in decline.  In fact, they are said to be equivalent to those observed more than 200 years ago.

The observations were done at major reef-building colonies around the globe in the Indo-Pacific coral region and in massive Porites (a genus of finger-like stony coral) reef colonies in Australia, Hawaii, Thailand, the Persian Gulf and New Ireland.

The scientists say that the increase in reef calcification is probably due to enhanced coral metabolism and/or increases in photosynthetic rates of the symbiotic algae. The researchers expect the increases in calcification associated with ocean warming outweigh the decreases associated with higher CO2 levels.   “While initially showing a decrease in calcification up to 1964, ocean warming outweighs the CO2 effect and stimulates recovery of coral reef calcification”, says Richard Matear, one of the researchers, at Scienceagogo: 20041112235853data_trunc_sys.shtml

Enjoying a healthy reef of Roatan Island in Honduras. Photo (c) 2009 Erkki Siirila.