Archive for the 'Ecosystem restoration' Category

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.

Rehabilitation helps suffering coral reefs

Global climate change is expected to cause serious damage to coral reef ecosystems during the coming 50 years. The rising sea surface temperatures and increasing ocean acidification are so serious global threats, that even the relevance of reef rehabilitation at the local level can be questioned.

The answer to those who doubt is that well-managed reefs which are relatively free of human impacts have shown resilience to coral bleaching and reef mortality. On the other hand, the badly managed reefs which were already affected by local impacts (such as pollution and overfishing), have often shown very limited recovery or no recovery at all.

Future reefs may look like this: eroding coral rock with little live cover. Photo from Utila, Honduras, (c) 2011 Erkki Siirila.

When we try to manage human impacts in the world´s coral areas, reef rehabilitation techniques are an important tool. Rehabilitation together with other local management activities (regulation of fisheries, control of pollution, development of marine parks) is likely to improve ecosystem resilience. Those reefs which are well-managed will have a real possibility of surviving as productive and functional systems, when they are impacted by global environmental pressures.

The above is some of the key information included in the Reef Rehabilitation Manual edited by A.J. Edwards and published by Coral Reef Targeted Research & Capacity Building for Management Program, Australia, in 2010. The Manual, its sister publication Reef Restoration Concepts & Guidelines and other useful coastal management publications can be found at http://www.gefcoral.org. The direct link to the Reef Rehabilitation Manual is here: Reef Rehabilitation Manual

In spite of the considerable progress in coral reef restoration over the last 35 years, this field of science is still in its infancy. There have been a few successful rehabilitation projects already – and many others which have not met their goals.

Healthy coral builds incredible structures in the Red Sea. With the changing environmental conditions these living structures may disappear. Photo from Egypt (c) 2010 Erkki Siirila.

Reef Rehabilitation Manual states that the primary aims of this handbook are:

  1. “to reduce the proportion of reef rehabilitation projects that fail”,
  2. “to introduce protocols for methods that could allow larger areas of degraded reef to be repopulated with corals  whilst minimising collateral damage to reefs where corals are sourced”,
  3. “to highlight factors to take into consideration at the planning stage so as to minimise the risk of failure”, and
  4. “to underline the current limitations of reef rehabilitation”

The publication seeks to “disseminate protocols that will, on the one hand, increase the chance of success of active restoration projects and on the other, reduce the impact of these projects on the natural reef if they fail”.

The Manual tells us that normally a two-step process is required when we want to supply coral transplants for large scale rehabilitation projects. The steps are:

  1. small fragments of coral or coral spat (settled larvae) are reared in nurseries until they are big enough to survive on a degraded reef,
  2. the nursery-reared colonies are transplanted to stable reef areas (obviously attaching them securely is important)

Reef Rehabilitation Manual has three central technical chapters. They build on work and describe protocols which have been developed in several countries. The technical chapters help the reef manager construct and manage a nursery for farming of coral fragments, offer information on how to rear coral larvae for restoration, and give instructions for deployment of coral transplants on a degraded reef.

Finally, it is important to remember that the best alternative is to be proactive and avoid ecosystem degradation. The Manual provides this reminder: “Although restoration can enhance conservation efforts, restoration is always a poor second to the preservation of original habitats.”

Connectivity, coral reefs and marine parks

Water is in constant motion and transports sediments, nutrients and pollutants. At least during one life stage, most marine organisms move within the water stream, either passively or actively. Connectivity is the word used to describe all these movements.

Connectivity is an important consideration in coastal management and in the design of marine protected areas (MPAs) and MPA networks. When fish larvae and fertilized coral eggs move in water currents from one place to another, these movements become crucial for the location of the new generation of these animals.

Most marine organisms on reefs and in coastal waters are relatively sessile during most of their life. This sedentary lifestyle is abandoned during reproduction: most reef species produce pelagic eggs which become pelagic larvae. Some of these pelagic larvae become fish. When fish grow older, they may travel to another location, while juvenile coral colonies will generate a reef where the coral eggs and larvae end up – in case the marine environment is suitable for reef growth.

Some habitats are critical to the early developmental stages of fish, lobster, and shrimp, while others serve as spawning or feeding grounds. Marine organisms also migrate daily and/or seasonally between habitats. The daily shifts commonly involve nightly feeding migrations between feeding and resting habitat. In some fish species, these daily movements lead to nutrient transfer between seagrass/mangrove areas and the coral reef.

Connectivity is an important consideration in the management of this Red Sea coral reef surrounding an Egyptian island. Photo (c) 2010 Erkki Siirila.

The marine ecosystem is so complex that many connectivity issues are poorly known. Nevertheless, this field of marine ecology is advancing: better understanding is crucial for sound marine management.  An example of these advances is the publication in 2010 of “Preserving Reef Connectivity: A Handbook for Marine Protected Area Managers”, which can be found here: Handbook

Special attention in the Handbook (written by P.F. Sale et al., edited by Lisa Benedetti and published by UNU-INWEH), which is the main source for this Coastal Challenges’ article, is given to populational connectivity. This includes

  1. Evolutionary (genetic) connectivity; and
  2. Demographic (ecological) connectivity.

In the Handbook, number 1 is said to “be informative when considering long-term (evolutionary) and large-scale biogeographic dispersal patterns of organisms. It can also be useful for managers wanting to assess the genetic uniqueness of populations when making decisions concerning biodiversity preservation.”

Number 2 “involves the extent of linkages that occurs among nearby local populations of a species due to the exchange of individuals”. This type of connectivity is important for the design and management of marine protected areas (MPAs) and no-take fishery reserves (NTRs), and when we want to know the ideal amount of coral reef habitat to protect.

The results of recent investigations are clear: pelagic larvae do not drift aimlessly in the ocean. They use for example sensory capabilities to minimize the extent of dispersal. In many species the larvae have the capability to settle on suitable reef habitat and specific microhabitats.

Connectivity amongst populations of reef species is primarily due to dispersal during larval life; demographic connectivity takes place on scales of up to tens of kilometers. The concept of demographically well connected populations for example across the Caribbean is not true and belongs to the past. Only genetic (evolutionary) connectivity links these habitats far away from each other, when larvae occasionally get transported beyond the usual dispersal range.

When marine parks are intended to function as fisheries management tools, the smaller scale of demographic connectivity should be taken into consideration in the MPA design – and in the design of MPA networks. This type of connectivity is worth remembering also when coral reefs experience massive destruction (hurricanes, bleaching, crown-of-thorns attacks): demographic connectivity defines the limits of natural re-seeding.

Coastal development may damage important inshore areas used by developing fishes and other organisms. For example, pathways between these and offshore habitats may be disrupted. Negative impacts during an organism’s early life stages may also have consequences for the abundance of adults. In addition, linked food webs may be affected. Furthermore, daily or seasonal migration routes could be disrupted. – MPAs and MPA networks should be large enough to encompass the interlinked habitats.

Spawning aggregations of groupers are an exciting phenomenon in many parts of tropical seas. During large scale oceanic movements and gatherings, species behaving in this manner are vulnerable to overfishing. The spawning sites should be part of no-take fishery reserves (NTRs). (More information on NTRs specifically can be found in “Fully protected marine reserves: a guide” by Callum M. Roberts and Julie P. Hawkins, 2000, which can be downloaded from here: Guide)

In general, NTRs promote fish survival and reproduction even when serious overfishing takes place in the surrounding area. Studies have shown that four positive changes inside NTRs take place. These changes, which may benefit fished populations outside reserves, are summarized in the Handbook on reef connectivity. They are:

  1. Increased reproductive output (increases in fish abundance, spawning biomass, mean age, and body size result in this change)
  2. Higher net export of juveniles and adults (to surrounding fished areas);
  3. Higher net export of eggs and larvae (to surrounding fished areas); and
  4. Protection and recovery of crucial habitats/ecosystems (key underwater areas for the fished species)

The NTR studies indicate that when neighboring NTRs are not more than 10-30 km apart, appropriate levels of populational connectivity exist for most reef species targeted by fishermen. As indicated above, early hydrodynamic models predicted dispersal distances of hundreds of kilometers. Based on new evidence, even relatively small MPAs may be self-sustaining.

In a world of climate change, it is important that coral reefs and other coastal ecosystems are managed as effectively as possible. Their natural resilience can be supported by taking connectivity into consideration.

Thai challenge: warming seas bleach the coral

Several popular dive sites at seven marine parks have been closed to diving in Thailand. The ban covers coral reefs suffering from serious coral bleaching which started in 2010. The reefs which will be off-limits to diving are located in the Andaman Sea on Thailand’s west coast.

The purpose is to let the reefs rest under circumstances in which as few environmental pressures as possible affect the coral. “We will give the reefs time to recover naturally,” Sunan Arunnopparat, director general of the National Parks, Wildlife and Plant Conservation Department, said in an interview. The comments were published by the Thai newspaper The Nation on 20 January, 2011.

The director general added that more than 80% of the coral in the areas was affected by bleaching.  Overall the situation is serious: more than 50% of all the reefs in southern Thailand show signs of whitening and loss of colour. Divers visiting Thailand tell that it is not question of bleaching only. They say that at least in some places a high percentage of the bleached coral has actually died.

Widespread bleaching and death of corals could be one of the first concrete signs of climate change in the ocean. Photo (c) 2010 Erkki Siirila.

While announcing the ban, Sunan Arunnopparat also told that the restrictions were introduced in consultation with academics. As regards the duration of the emergency measures, Sunan Arunnopparat said: “The recovery of the coral will be monitored before the ban is lifted.”

In addition to the reef closure, the Department will apply other habitat protection measures. Limiting admissions to national parks and educating the tourists in environmentally sound practices were mentioned as examples.

The new restrictions are likely to hurt Thailand’s tourism industry and especially the dive business in the short term. In the long term the dive business may benefit. In case the new conservation measures lower enough the combined environmental stress factors on the reefs they could prove helpful – globally coral reefs are mainly threatened by the warming of seawater. The root cause is climate change.  Not only tourism is at stake, reef health is crucial to maintenance of local fisheries and prevention of coastal erosion.

The coral bleaching – whitening due to the loss of the symbiotic zooxanthella microalgae from coral tissues – was first observed across the Andaman Sea in May 2010 after a surge in seawater temperatures. Serious bleaching was reported also from other parts of the Indian Ocean in 2010. Furthermore, similar news came from some reef areas in the western Pacific Ocean and the Caribbean Sea.

Bleached coral often dies. As coral grows slowly, the recovery of a reef will usually take years. As coral reefs often suffer from several environmental stress factors, there is no guarantee that a damaged reef will recover.

Healthy reefs are important for the success of dive tourism in many developing countries. Photo (c) 2010 Erkki Siirila.

Revolutionary method: gypsum controls runoff

An interesting discovery is helping in Baltic Sea conservation efforts in Finland. It involves the use a gypsum, which is a chemical substance known to most of us.

The environmental challenge we are talking about is that phosphorus, an essential plant nutrient, is transported from the farming fields through runoff into the rivers and sea. In the sea water, elevated levels of phosphorus cause eutrophication.

Yara, a chemical company, has together with a few Finnish partners developed a gypsum-based technique to stabilize soil particles in the farming fields. The method reduces soil (and nutrient) erosion caused by surface runoff.

The results achieved indicate that a high percentage of the phosphorus stays in the soil when the new technique is used. Consequently, harmful nutrient inputs into the waterways and sea are highly reduced. The new method also helps the farmer as more phosphorus is available for the agricultural plants. Furthermore, there is less need for costly, additional phosphorus fertilizers.

In spite of not being visible in this image, eutrophication caused by excessive nutrients is a problem on the Baltic coast of Finland. Photo (c) 2010 Erkki Siirila.

The method involves spreading of a gypsum-based product on the farming field after harvest or before planting. The product, which is basically gypsum (calcium sulphate), infiltrates with water into soil. According Yara, this well-known chemical compound in its slightly developed form improves “particle aggregation and dissolved phosphorus retention”. In addition, “better soil structure means that the earth resists rain and melting snow better and therefore prevents erosion and phosphorus leakage”.

Gypsum is useful to the farmer also because it improves the plants’ ability to utilise the phosphorus reserves of the soil. In addition, farmers can continue their agricultural activities as before. For the gypsum treatment to be effective, it would need to be repeated once in three to four years.

Gypsum treatment of the soil could be important news for many countries. Soil,sediment and nutrient runoff is degrading forestry and agricultural areas around the world. This runoff is also killing shallow marine ecosystems. Could gypsum help save the world’s endangered coral reefs?

A brochure on the gypsum-based method to control agricultural runoff into the sea can be found here:

http://orgprints.org/16037/1/Pietola.pdf

Living Planet Report and the fisheries’ footprint

“Living Planet Report 2010 – Biodiversity, biocapacity and development” is an important conservation document published in 2010.  As regards coastal zone management, the report presents alarming information of world fisheries.

Under the heading “Focus on our footprint: marine fisheries” the report reminds us of certain key facts:

  • Wild fish is an important food source for billions of people. Nearly 3 billion people get 15% or more of their crucial animal protein intake from fish.
  • Most stocks of the top 10 commercial species – this corresponds to about 30% of marine catches – are either fully exploited or overexploited.  No significant  increases in the catches of these stocks can be expected in the near future.
  • 52% of all marine fish stocks are fully exploited already.
  • 28% of marine fish stocks monitored in 2007 had serious problems. Of these endangered stocks 19% were overexploited, 8% were depleted and only 1% recovering from depletion.
  • The habitats that support the fisheries are important areas to conserve. These areas are not only fish nurseries and spawning grounds. They are important also from the biodiversity point of view.  In addition, they provide coastal protection during storms and support marine-related tourism.

Bad governance is an expression which is used in the Living Planet Report to describe the state of the world fisheries – these two words are likely to be a good summary.

School of small barracudas in the Red Sea. Photo (c) 2010 Erkki Siirila.

What does the Report propose in order to make our fisheries better managed? These are some of the suggestions found in the publication, which concentrates on the human footprint on our planet:

  • Science-based fisheries management can help increase fisheries production in the long term. It also makes the fisheries and marine ecosystems more resistant to pollution, ocean acidification and climate change. Other benefits include safeguarding important food supplies for coastal communities.
  • In order to make fisheries management sustainable, the following needs to occur in specific activity areas: Drastic catch reductions in many marine fisheries need to accepted now in order to have benefits in the long term. Fishing governance needs to be improved especially in areas beyond national jurisdiction. Expansion of aquaculture needs to be balanced with the protection of wild fish stocks, biodiversity and habitats.
  • Overall, fisheries’ biocapacity needs to be increased. This means maintaining fish stocks at optimal population and age levels to maximize growth. At the ecosystem level this means better habitat conservation by establishing protected areas, controlling coastal pollution and curbing carbon dioxide emissions.

The WWF Living Planet Report 2010 can be downloaded from here:

Living Planet Report 2010

Mangroves and environmental impacts

Like the previous Coastal Challenges’ article, this summary of mangroves and environmental impacts is based on How to assess environmental impacts on tropical islands and coastal areas: South Pacific Regional Environment Programme (SPREP) training manual. The manual was edited by Richard A. Carpenter and James E. Maragos.  This handbook was prepared by Environment and Policy Institute, East-West Center, in 1989, and sponsored by Asian Development Bank.

The Carpenter and Maragos manual presents useful tips and background material for the management of mangrove communities in the tropics.  (The three most important marine ecosystems in the tropical coastal zones are the coral reefs, mangroves and seagrass beds.) The information on mangroves is summarised in a slightly edited form below: 

Sustainable uses and values of mangroves: Mangroves maintain nearshore fisheries and are an important area for fish & shellfish production in the sea. Mangrove communities also protect the coast from storms; especially low-lying areas benefit.  By trapping of nutrients and sediments from drainage, mangroves protect coral reefs, sea grass meadows and coastal waters in general. In addition, wood and other forest products are obtained from mangrove areas.

Sensitivity to environmental changes: Changes in tidal flushing patterns damage mangroves.  Oil spills can be extremely harmful to mangrove communities.  Mangroves are also sensitive to salinity changes.  Furthermore, excessive harvesting can weaken the natural production and regeneration capacity of the mangrove ecosystem.

Development hazards: Environmental impacts which change the topography and water flow in the mangrove areas can be considered development hazards (for example damming, dredging, bulk-heading and impoundment). Activities which result in excessive sediment production may also damage the mangroves. Freshwater discharges, freshwater diversions and groundwater pumping are other examples of possible development-related threats. Naturally, clear-cutting, deforestation and land reclamation may seriously damage or destroy a mangrove area.

Mitigation: Natural characteristics of water movement need to be maintained. Harvesting limits need to be set and enforced. Buffer zones are a useful tool in mangrove management.

Mangrove management is an important component of coastal zone management when we get prepared for global climate change and sea-level rise. Youtube provides access to a Wetlands International video highlighting these issues. The link to the video is here: