USGS Multimedia Gallery: African Dust, Coral Reefs and Human Health

[OBSERVAÇÃO preliminar importante (extraída do GLOSSÁRIO DE ECOLOGIA): "Estudos recentes realizados por Leon Rotstyn (do CSIRO − Commonwealth Scientific and Industrial Research Organisation, Instituição da Austrália) e por Ulrike Lohmann (da Universidade de Dalhousie, Canadá)mostraram que as interações entre dióxido de enxofre e formação de nuvens (poluentes emitidos nos EUA e Canadá) provocavam condensação e precipitação de chuvas na América do Norte, que assim deixavam de se deslocarem para o norte da África. O sofrimento nessa região tende a se agravar porque o solo desnudo (pelas secas contínuas) reflete mais radiação solar enquanto os aerossóis de poeira refletem os raios de volta, mantendo assim a atmosfera sempre quente; e sem vegetação a erosão eólica se acentua,
reduzindo assim as propriedades produtivas do solo"].
[Vejam o vídeo do USGS e depois, leiam todo o texto. Chamo a atenção para as afirmações de um dos cientistas entrevistados, GINGER GARRISON, que assinalei em negrito]

USGS Multimedia Gallery: African Dust, Coral Reefs and Human Health

Narrator - Coral reefs worldwide are in decline. Over the last three decades, coral reefs throughout the world have been damaged by human activities, powerful storms, abnormally high water temperatures, and diseases. Where coral has died, algae have quickly grown in its place. Scientists are particularly concerned because, once damaged, these key marine ecosystems are not recovering.
Ginger Garrison - Diseases were first reported on coral reefs in the Caribbean in the early 1970s. But today disease is considered probably the primary factor causing mortality in corals. Today, there are more diseases on coral reefs. There are more coral species that are affected by disease and disease is causing more mortality. Caribbean coral reefs were the first ones that were hit and hit hardest, the problem today is global and it is very serious.
Narrator: Currently, there are around 30 types of diseases or disease-like states recognized. Thus far, scientists have identified the causes of six coral diseases: sea-fan disease (or Gorgonian aspergillosis), black band disease, white plague, white pox, bacterial-induced bleaching, and pink-spot disease.
Why are the diseases on an increase? Why are they so widespread? Why are reefs worldwide in decline? What large-scale processes could be at work?
Hundreds of millions of tons of dust are carried each year from the Sahara and Sahel regions of Africa to the Caribbean, the eastern United States, and beyond. At times, these dust air masses cover the tropical Atlantic and the entire Caribbean Sea. Is this large-scale system having an effect on coral reefs throughout the Caribbean?
African desert locusts are known to be periodically carried along with the dust and arrive alive on several Caribbean islands. If a two-inch locust can survive the trip across the Atlantic, can smaller organisms such as the disease-causing microbes survive as well? Scientists at the U.S. Geological Survey are trying to determine whether downwind ecosystems are being harmed by nutrients, microbes, or chemical contaminants carried with African dust.
Suzette Mormon - By the time the African dust reaches the Caribbean, the particles are very small, about one micron in diameter. These fine particles are easily inhaled and less easily exhaled. The compositions of these particles are primarily clay with some other smaller amounts of gypsum and iron oxides. The iron oxides are important because they work as a sponge for other metals and they carry with them things, in particular arsenic.
Narrator - To test the hypothesis that African dust is a factor in the deteriorating state of Caribbean coral reefs, air samples were collected from the source region of Mali in Africa, off the western coast of Africa in Cape Verde, and at downwind sites in Trinidad and Tobago in the southeastern and the U.S. Virgin Islands in the northeastern Caribbean.
Suzette Mormon: The dust in the downwind sites had slightly lower concentrations of total metals but the bio-accessibility of these metals was higher. This may be related to the very fine particle size in these iron oxide coatings, which tends to absorb these metals on them and release them very easily. The very fine particles are very easy to inhale. We know that the less than 5-micron particles will travel further into the lungs. We know that these very fine particulate matters have been correlated health wise with increased rates of heart attack and stroke and exacerbations of asthma and other respiratory diseases.
Chris Kellogg: What we wanted to know is whether viable bacterial and fungal spores could be transported long distance across the ocean in African dust events, and the answer is yes. We found much higher numbers of microbes, say 10 to 100 times more cultured bacteria, when we tested air samples from Mali, West Africa, a source region, compared to downwind sites in the Caribbean. The downwind samples are complicated, because you have local aerosolized microbes and then you have microbes that have come in the dust and as of now there is no good way to tell the source of a microorganism. For example, Garriet Smith isolated Aspergillus sydowii, which is a fungus that causes disease in sea fans, from a dust event in the Virgin Islands, but the question remains is the source of that fungus local or long distance?
Narrator - Microarray technology recently developed at the Lawrence Berkeley Lab in California is using molecular techniques to identify microorganisms in dust samples.
Eoin Brodie: At Lawrence Berkeley National Lab, we have developed a microarray technology called the folic chip, which can be used to simultaneously detect up to 30,000 different types of bacteria in any environmental sample. Working with researchers at the USGS, we have been attempting to identify the microorganisms present in African dust samples, and we hope to correlate the presence of those organisms with coral disease and changes in human health in the Caribbean. We receive a filter sample containing dust. We extract the DNA and apply the DNA to this microarray device, the folic chip. Within 24 hours, we can identify the organisms present in a sample and then inform researchers at USGS which organisms are associated with dust and which organisms may be associated with coral disease.
Narrator - Although African dust has been carried out of the Sahara and into the Caribbean and the Americas for hundreds of thousands of years, there have been significant changes in the past 40 years: the quantity of dust has increased and the composition has changed. Scientists have identified carcinogens, neurotoxins, endocrine disruptors, and suppressors of immune systems.
Ginger Garrison - Greater amounts of dust have been carried out of the Sahara since the 1970s due to a number of factors: global climate, changes in regional meteorology, and local human activities. During that same time, the composition of the dust has changed. Toxic chemicals are produced by the combustion of biomass, fossil fuels, the burning of garbage, and things like plastics in the source region. These have been carried along with the dust particles from Africa into the Caribbean. At the same time in the source region, they are using pesticides for things such as malaria from mosquitoes, on their crops, and also against locust plagues, and those pesticides are also coming across.
Narrator -These chemicals can travel around the globe and have long-term effects on ecosystems because they persist in the environment, accumulate in organisms, and are toxic in low concentrations.
Ginger Garrison - The question is, can we really point our finger at any one source for this load of inorganic contaminants that we are finding in the atmosphere, both in Mali and also in the Caribbean, and we think not. We think that there is an underlying burden of contaminants. If you look at the pollution plume that will come out of the northeast United States, crosses the Atlantic into Europe, mixes with air pollution from Europe, that can conceivably be brought down south, especially with a cold front in winter, into Africa where it mixes with the African and Saharan air layer and then everything comes over into the Caribbean, comes around again.
Narrator - Scientists are beginning to test the toxicity of African dust and associated chemical contaminants on the life stages of many kinds of marine organisms, including corals, to see if they harm marine life and how they do so. Preliminary laboratory research has found some disturbing results. Two of the pesticides most commonly found in dust air samples from source and downwind sites were found to interfere with the settlement of coral larvae - an important stage in the life of a coral.
The movement of small particles of dust, metals, and toxic chemical pollutants through the air, across the oceans, and among continents is occurring. USGS research continues on this global issue.

USGS Multimedia Gallery: The Effects of Urbanization on Stream Ecosystems (extended) Part III: Study Results

[Hello dear friends: this is a quite interesting video from the UNITED STATES GEOLOGICAL SURVEY, about urban development that influences stream ecosystems, an approach that interests particularly to us, because most of our urban waterflows are also affected in a similar way. I have chosen just one of the 3 videos they have of the project]
Jerry McMahon: Over the last 10 years the US Geological Survey’s National Water Quality Assessment Program has examined the effects of urban development on stream ecosystems. In this study, the two primary objectives were first of all to look at the physical, chemical and biological responses of streams to urban development. And also, to look at how those responses varied across the country. OK, our first finding was that all three biological communities we examined, algae, invertebrates and fish responded to urban development. Urban development significantly affected one or more biological communities in eight of the nine metropolitan study areas with Denver being the exception.
In Portland, which is shown in this slide, all three communities responded negatively to urban development. Because invertebrate communities showed the strongest and most consistent response to urban development across the country, we will focus on the response of macroinvertebrate. The second finding is that declines in aquatic insect communities are noted at the early stages of urban development. Unlike the hypothesized response, even small levels of urban development had an immediate negative effect on aquatic insects. There’s no period of resistance to the effects of urban development. This is illustrated by the immediate decline in the aquatic insect community composition as the level of urban development in the Boston study watersheds increases. This response is continuous over the entire range of urban development. The aquatic insect communities studied in the Boston watersheds never reach a state of exhaustion.
Our third finding is that urban development is often accompanied by a loss of pollution sensitive species and a shift toward communities that are dominated by pollution tolerance species. EPT Richness represents the sum of sensitive insect species in the order of Ephemeroptera - mayflies, Plecoptera – stoneflies and Trichoptera – caddisfly. This figure indicates the difference in the number of sensitive EPT invertebrate species found in watersheds at the high end of the urban gradient and at the low end. A substantial decline in EPT species richness occurred in all but the Denver, Dallas and Milwaukee study areas. Measures of EPT Richness are commonly used to assess biological condition of stream in state biomonitoring program.
A biological community that includes sensitive species is often an indication of healthy stream ecosystem and therefore changes in the presence of sensitive species provides useful information about the biological condition of the stream. Our fourth finding is that important regional differences existed in the types of land cover that were being converted to urban uses. Across the nine regions of the country that were studied, urban development occurred primarily through the conversion of either agricultural or forested lands. Forest is the dominant pre-urban development land cover in Portland, Salt Lake City, Birmingham, Atlanta, Raleigh and Boston; whereas, in the other three study areas land being converted to urban uses is associated with some form of agricultural activity. The characteristics and activities associated with these two land cover types may mask or escalate the influence of urban development on stream ecosystems.
For example, although agricultural practices have evolved dramatically in the last hundred years, nutrient enrichment, soil erosion, monocultural practices and the loss of natural habitat are still major concerns. Watersheds where the predominant pre-urban development land cover is agricultural land already have some degree of water quality impairment prior to the urbanization that can obscure the effects of urban development. This may help explain the very small loss of sensitive taxa in areas where urban development occurs on land that previously was in agricultural uses. Sensitive species had already been lost before urban development occurred. So how can this information be used?
The information we’ve developed on the response of stream ecosystems to urban development will help urban planners and other stakeholders clarify the most appropriate strategies in managing, protecting and restoring urban streams. Two findings are of particular importance. First, the fact that macroinvertebrate community conditions starts degrading almost immediately once urban development begins suggests that a great deal of caution should be exercised in thinking that there is a safe zone of urban development at least for a stream’s macro invertebrate communities. Second, we now know that streams in different regions of the country respond differently to urban development. This is due to regional differences in the overall template of factors that affects stream ecosystems such as climate and the types of land that are being developed for urban uses. These regional factors also affect the response of hydrology, habitat, water chemistry and stream biota. Management approaches have to be shaped by an understanding of how this regional template helps determine what is possible to achieve in terms of water quality, criteria and standing.
For additional information about our project, please visit the project website where you can obtain both reports as well as the data used in the project. I’m Jerry McMahon and on behalf of all my colleagues, I’d like to thank you for your interest in understanding the effects of urban development on stream ecosystems.
USGS Multimedia Gallery: The Effects of Urbanization on Stream Ecosystems (extended) Part III: Study Results

AFRICAN SNAILS THE LATEST WEAPON IN POLLUTION CONTROL

[SCIENTIFIC AMERICAN video]
[Watch the video: http://www.scientificamerican.com/video.cfm?id=776291606001][and follow the text below, extracted by Breno Grisi]

The Achatina snail [Achatina fulica] is usually found in the sub-Saharan Africa. This one is it working in Russia. Its task it is to sample the atmosphere at the water treatment plant at St. Petersburg, monitoring air pollution produced by the sewage works incinerator. The living sensor reacts to gases in the air, according to environmentalist researcher [Russian researcher].
When gas concentration changes drastically the molecules get disturbed. It can change relatively and it can behave as a connective one. At the same time the frequency of [...] rates increases, as a matter of fact, this reaction is a test for air pollution.
Scientist are able to monitoring changes in the snail heart beat and behaviour by watching it in real time on a computer screen. This kind of snail can live for up to 10 years, it [...] to 20cm in length. It was chosen for the task because they have lungs and breathe in a similar way to humans. The snails are not being exposed to dangerous levels of gas, says leader researcher [...] Snails are not breathing smoke but a gas with a thousand times lower concentration of the smoke. Why? Because people are concerned about the quality of air outside the plant restricted zone.
Animals have been involved in the environmental monitoring in St. Petersburg before with crayfish tasting water quality in the [Never???] river. Now this not so little snail is joining the effort to clean up the atmosphere. [...]