Archive for the 'Environmental impacts' Category

Microplastic pollution – a serious threat to marine ecosystems

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

Pioneering research has shown that plastic waste entering the ocean may have more serious negative effects on marine life than what was previously thought. Two studies published in Current Biology focus on the ecosystem effects of microplastic fragments less than 1 mm in diameter. The very small pieces of plastic have been polluting the ocean for about half a century.

Previous research has concentrated on the effects of bigger plastic objects in the marine ecosystem. This time the focus is on the fragments, which are produced for example as a result of gradual breakdown of plastic bottles in nature.

The tiny plastic particles are so small that wastewater treatment plants cannot stop them from entering the sea. A serious challenge for waste management is that this pollution does not originate only in what we normally consider plastic. The sources include synthetic textiles e.g. polyester – many of our clothes release a high number of microscopic pieces of plastic fibre when they are washed. Microbeads from cosmetic facial scrubs are one more source of harmful plastic particles. On the shores and in the sea, the microscopic plastic waste sinks into the sediments in high concentrations.

An additional problem with microplastics is that, in addition to the direct effects, they transfer harmful chemicals to marine organisms eating them. This was shown to take place in the case of lugworms by Mark Browne and his colleagues (link to Abstract). Lugworms (Wikipedia Lugworm) are an example of a common North Atlantic species using the sediments as food source. Starfish and sea cucumbers have similar feeding strategies. Mark Browne’s work was completed at Plymouth University, UK.

Plastic waste entering the Atlantic via Rio de la Plata (River Plate), Buenos Aires, Argentina.

Plastic waste entering the Atlantic via Rio de la Plata (River Plate), Buenos Aires, Argentina.

The harmful substances within the microplastics include antimicrobials, hydrocarbons and flame retardants, which are often persistent and may reduce health and biodiversity. Furthermore, minute plastic particles concentrate substances from the surrounding water on their surface: to name two examples, detergents and pesticides can be detected. The chemicals may be carried over to the next predators in the food chain – lugworms are eaten by flounders and wading birds. The harmful substances could also accumulate in the top predators, perhaps even in us humans. If lugworms are seriously affected, as they are, the whole food chain could be subject to significant adverse effects.

In the study by Stephanie Wright, University of Exeter, UK, and her colleagues, it was found that those lugworms which (in laboratory tanks) were subject to varying levels of plastic contamination, gained less weight than the worms in a clean environment. Consequently, the worms suffering from the consequences of plastic pollution had less energy for growth and reproduction. The worms were also likely to be less efficient in their important ecosystem service, i.e. in eating and keeping the sediments healthy and oxygenated for other animals. The article by Wright et al. is here: http://download.cell.com/current-biology/pdf/PIIS0960982213013432.pdf?intermediate=true .

When interviewed by the BBC, Dr Browne summarised his earlier findings relating to 18 sediment samples from the beaches in several countries: “We found that there was no sample from around the world that did not contain pieces of microplastic.”

Based on these two ground-breaking articles in Current Biology, there seems to be an urgent need to develop the use practices and waste management techniques of plastic products in our societies. This is an important coastal and marine conservation issue.

In addition to the material published in Current Biology, summaries published by the British BBC and The Guardian, were helpful in the preparation of this Coastal Challenges’ article.

 

Human wastewaters infect elkhorn coral

A human pathogen has been shown to contribute to the degradation of elkhorn coral (Acropora palmata) colonies in the Caribbean Sea. The pathogen Serratia marcescens is known to be present in human wastewaters, which enter the coastal marine areas untreated in many parts of the Caribbean. In the recent study by K.R. Sutherland et al., strain PDR60 of the pathogen was shown to cause disease signs in A. palmata colonies in as little as four or five days, when the surrounding waters were polluted with S. marcescens.

In the Caribbean the lack of wastewater treatment is a common problem. This colony of elkhorn coral looks healthy in spite of the fact that raw sewage enters the sea 100m from the reef. Photo taken in Utila, Honduras, copyright (c) 2011 Erkki Siirila.

In 2003 there was an outbreak of this coral disease called acroporid serratiosis (APS). During the episode, the corallivorous snail Coralliophila abbreviata and stony coral Sideastrea siderea were noticed to be play a role in the development of the disease. Now, in aquaria experiments, wastewater has been demonstrated to be a definitive, direct source of the disease, while C. abbreviata and S. siderea are known to act as vectors and reservoirs, which may also to contribute to the infection of A. palmata.

The research results by K.R.Sutherland et al. published in 2011 demonstrate for the first time that a human pathogen can be passed from us humans to marine invertebrates and infect them. The authors of the study “Human Pathogen Shown to Cause Disease in the Threatened Eklhorn Coral Acropora palmata” say that “these findings underscore the interaction between public health practices and environmental health indices such as coral reef survival”.

A direct link to the article is here:  Elkhorn and sewage

Coastal zone of Chile: ten management recommendations

Chile is a country with thousands of kilometres of coastline (the exact length of the coast depends on the definition applied). Naturally, moving towards integrated coastal zone management benefits a country like that.

The Coastal Challenges editor did a consultancy in the Fourth Region (Coquimbo Region) of Chile a few years ago. One of the results was a set of general guidelines for integrated coastal management in that region. In the ten conclusions/recommendations the local experiences were combined with the lessons learned in coastal management internationally.

A powerful tsunami in 2010 made Chileans aware of the need for sound coastal management. This Chilean government fax indicating there was a tsunami risk was not enough to result in massive coastal evacuations. As a result, lots of human lives were lost.

The conclusions and recommendations for integrated management of the Coquimbo coastal area are listed below:

  1. Integrated management of the coastal zone is a learning process with incremental implementation, feedback and adjustment mechanisms.
  2. At all levels of action, it is important to build the integrated management on a sustainable  financial and economic base, for example through self-funding.
  3. It is important to incorporate in the process the opinions of all the involved and interested parties, for example by applying conflict resolution mechanisms.
  4. It is essential that the actions keep focus on just a few issues which are understood by all the participants in the process. The focus on the issues means that an exact definition of the coastal zone is not a precondition for the action to begin.
  5. In general, construction on the local institutional roots is the safest option. E.g. the existing management systems, which are politically supported, can be modified instead of building totally new management institutions. Also in this case, the application of innovative ideas for real integration is important.
  6. A long-term vision is essential, and as part of this, opportunities should be left open for the future generations.
  7. The management should be based on good knowledge of the laws of nature. Implementation would need to be proactive instead of retroactive.
  8. It is important that the decision-making system is just and efficient.
  9. It is essential to understand that combining sustainable management with the poverty of resource users is difficult. Because of this, development of economic alternatives for the least favoured groups is needed.
  10. In sustainable coastal zone management, integration mechanisms are only one element. Specific action is needed also in the management of key species and habitats, pollution control, land use planning and environmental impact assessment. In addition to integration, sectoral activities in these and other action fields need to continue. (Naturally, sector-specific work needs to go on, but the sectoral actions should no more be implemented in isolation from other coastal zone activities.)

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

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 Underwatertimes.com 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.

Shifting baselines threaten marine conservation

About 12 percent of the Earth’s land surface is conserved in some way; the corresponding figure for the oceans is little more than 1 percent.  This is the starting point for the battle for more marine protected areas (MPAs), which Dr. Sylvia Earle, a well-known U.S. marine scientist, has initiated.  Dr. Earle’s thoughts are described in the October 4, 2010, print and iPad editions of Time magazine.

The article written by Shaul Schwarz (reportage by Getty for Time) helps us understand that in spite of being immense, the oceans are not invulnerable – this is why the urgent changes in marine management proposed by Earle are needed.

To Earle, the extremely limited coverage of marine protected areas reflects the fact that we actually consider the oceans as a “supermarket and sewer”: The seas are being overfished by trawlers and long-liners, and this is made possible by government subsidies. More than 90 percent of the populations of large predatory fish like sharks may have been lost while those of the important food fish bluefin tuna are only a fraction of their original levels. The Time article indicates that actually a global disruption of the marine food chains is taking place.

The article on Earle describes the situation of the world’s coral reefs, another biodiversity hot spot, by stating that “pollution and fertilizer runoff from agriculture have pushed one-third of the more than 700 reef-building corals close to extinction; 70 percent of all coral reefs could be gone by midcentury”.

Unauthorised fishing keeps the fish populations of this Caribbean reef at a low level. The baseline values are not well known either. Image from the Utila marine park,the Bay Islands of Honduras, (c) 2010 Erkki Siirila.

Because of the burning of fossil fuels, our seas are becoming more acidic – the carbon dioxide dissolving in the seas lowers their pH. As the oceans’ capacity to store carbon is 50 times that of the atmosphere, the oceans were thought to be a buffer to the adverse effects of climate change. This thinking is changing as no one can predict the outcome accurately. What is known already is that the increasing acidity of the oceans will cause calcification problems to many marine animals. This will weaken their physical structures.

After all, the biggest problem may be the “shifting baselines” (an expression used by marine scientist Daniel Pauly and cited in the Time article).  The expression means that ”we can’t tell how bad it’s gotten because we don’t remember how good it was”.

As regards Dr. Earle, she plans to stop the degradation of the oceans (or at least alleviate the problems) through her nonprofit organisation Mission Blue. Earle has already found many influential supporters who agree on the importance of new marine sanctuaries in key biodiversity areas. The new MPAs would not stop climate change but they would keep the environmental pressures under control locally and regionally.

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: