Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The exhorbitant price of unmanaged shrimp farming

14.01.2005


Water quality in the Rio Chone estuary in Ecuador has degraded over the last three decades by a combination of man-made impacts, including the input of organic wastes from shrimp farming activities located in what were once tropical mangrove forests.



An article in the current issue of the Journal of Coastal Research describes water quality experiments by University of Rhode Island oceanographers Diana Stram and Chris Kincaid and US Environmental Protection Agency (EPA) oceanographer Dan Campbell to assess the extent of water quality degradation in this ecologically sensitive area. The project was funded by a URI/EPA cooperative fellowship agreement and by the URI Coastal Resources Center.

The Rio Chone estuary has a history of water quality problems due to the combination of seasonal climate influences and management of natural resources. The estuary is affected primarily by an influx of sediment because of erosion of hillsides and construction of ponds; seasonal climate changes combined with decreased freshwater flow; and shrimp mariculture development resulting in mangrove habitat loss and the flushing of shrimp pond production wastes into the estuary.


The team of scientists characterized the water quality problems in the Rio Chone estuary by modeling the seasonal distribution of biochemical oxygen demand (BOD) and dissolved inorganic nitrogen (DIN) within the water column. The model allows the scientists to simulate which areas of the estuary are at greatest risk for low water quality, as well as which regions are primarily contributing to the pollution of the estuary.

The model was run under varying water conditions, during both wet and dry seasons, and for a variety of pond effluent locations. The development of the shrimp mariculture industry without regard to its environmental impacts has led to increased BOD and DIN, which, in turn, has caused a number of problems in the estuary.

Shrimp mariculture effluents contain high concentrations of BOD, DIN, and salt (from high evaporation). In the dry season, when the estuarine salinity is inverted (with higher salinity at the head than at the mouth) and circulation in the estuary is sluggish, elevated BOD concentrations from the pond effluents are not flushed from the upper estuary leading to areas of extreme oxygen depletion.

Ammonia represents a large proportion of the DIN concentration. Ammonia can impact aquatic life by acute and chronic toxicity as well as ammonia oxidation, which reduces dissolved oxygenlevels. Ammonia in shrimp ponds causes high mortality rates and can also cause low growth rates in shrimp. Low dissolved oxygen concentrations also increase the toxicity of ammonia to shrimp. Thus, a combination of chronic dissolved oxygen problems and an increase in nutrients can lead to serious effects of decreased water quality on shrimp growth. Increased nitrogen can also contribute to the development of toxic phytoplankton blooms such as red tides. Red tides have not occurred in the Rio Chone, but the increased nitrogen loading may allow them to develop.

The average production in shrimp ponds in the Rio Chone has decreased over the last decade. Increased DIN (and therefore increased ammonia) coupled with increased BOD has likely produced this decline.

The conversion of 90% of the area’s mangrove forests to shrimp mariculture ponds is of particular importance to water quality issues. Studies have shown that mangroves can be used for removing excess nutrients from coastal waters, and mangrove sediments may also be able to absorb some of the BOD from pond effluent.

Other studies have attempted to link water quality with profitability of shrimp mariculture. In the Rio Chone, the ponds closer to the mouth of the estuary, where there is more well-flushed water than the ponds located in the upper regions of the estuary, enjoy higher growth rates of shrimp.

"Our results suggest that site selection of shrimp ponds as well as restoration plans for mangroves should consider the hydrodynamic regime of the estuary in order to maximize pond production and maintain estuarine water quality," said Stram. "Site selection and the subsequent conversion of mangroves to ponds near the head of the estuary should be avoided in order to sustain water quality and prevent seasonal self-pollution problems in pond production."

Lisa Cugini | EurekAlert!
Further information:
http://www.gso.uri.edu

More articles from Ecology, The Environment and Conservation:

nachricht How does the loss of species alter ecosystems?
18.05.2017 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

nachricht Excess diesel emissions bring global health & environmental impacts
16.05.2017 | International Institute for Applied Systems Analysis (IIASA)

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Strathclyde-led research develops world's highest gain high-power laser amplifier

The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.

The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

New insights into the ancestors of all complex life

29.05.2017 | Earth Sciences

New photocatalyst speeds up the conversion of carbon dioxide into chemical resources

29.05.2017 | Life Sciences

NASA's SDO sees partial eclipse in space

29.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>