Archive for the 'Ecosystem restoration' Category

Rehabilitation helps suffering coral reefs

Published April 28, 2011 Climate change , Coastal management , Coral reefs , Ecosystem restoration , Marine parks Closed

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

Published February 7, 2011 Coastal management , Connectivity , Coral reefs , Ecosystem restoration , Fisheries , Marine parks Closed

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

Published January 23, 2011 Climate change , Coral reefs , Ecosystem restoration , Indian Ocean , Marine parks , Tourism Closed

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

Published January 6, 2011 Baltic Sea , Coastal management , Coral reefs , Ecosystem restoration , Environmental impacts , Eutrophication , Sediment control Closed

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