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<DIV><FONT size=4>Antibiotic pollution can disrupt aquatic food
chains</FONT></DIV>
<DIV class=author>Athar Parvaiz</DIV>
<DIV class=source>29 June 2012</DIV>
<DIV class=date><A
href="http://www.scidev.net/en/south-asia/news/antibiotic-pollution-can-disrupt-aquatic-food-chains.html">http://www.scidev.net/en/south-asia/news/antibiotic-pollution-can-disrupt-aquatic-food-chains.html</A></DIV>
<DIV class="article_content cf">
<P><SPAN>[SRINAGAR] Indian scientists have found that diatoms, primary
food-producers in aquatic food chains, undergo significant variation after
being treated with commonly used antibiotics. </SPAN></P>
<DIV>
<P><SPAN>The new findings on diatoms follow a 2011 study by Swedish scientists
from the University of Gothenburg, Chalmers University of Technology, and Umeĺ
University, who reported antibiotic contamination in river sediment samples
collected near an Indian waste water treatment plant processing effluent
from more than 90 bulk drug manufacturers. </SPAN></P></DIV>
<P><SPAN>Recently, scientists Priya M. D’Costa and Arga Chandrashekar Anil of
the National Institute of Oceanography at Dona Paula, Goa, studied the effects
of streptomycin, penicillin and chloramphenicol on diatom communities and
published their findings in <EM>Current Science</EM> (April 2012).</SPAN></P>
<DIV>
<P><SPAN>"These antibiotic concentrations were chosen to mimic conditions in
highly <A
href="http://www.scidev.net/en/agriculture-and-environment/land-water-pollution/"><FONT
color=#336699>polluted environments</FONT></A>. For example, untreated sewage <A
href="http://www.scidev.net/en/agriculture-and-environment/water/"><FONT
color=#336699>water</FONT></A> and aquaculture pond sediments where antibiotics
can enter the sediments directly without undergoing any purification process,"
the <EM>Current Science</EM> study says. </SPAN></P></DIV>
<P><SPAN>It suggests that while chloramphenicol directly affects a diatom
community, streptomycin has the potential of damaging it. Penicillin, on the
other hand, can affect diatoms only when mediated through a bacterial
colony.</SPAN></P>
<DIV>
<P><SPAN>"High antibiotic combinations reduced diatoms by 99–100 per cent and
favoured emergence of yeast, probably due to high concentrations and synergistic
effects," the study says.</SPAN></P></DIV>
<P><SPAN>Changes in diatom communities in individual antibiotic treatments were
either direct (chloramphenicol and potentially streptomycin) or
bacteria-mediated (penicillin). According to the study, "streptomycin and
chloramphenicol have the potential to affect diatoms directly by inhibiting
their protein synthesis."</SPAN></P>
<P><SPAN>In the chloramphenicol treatments, diatoms were reduced to 8–19 per
cent of control values while in streptomycin treatments, diatoms did not show a
dose dependent response at higher concentrations of the
antibiotic. </SPAN></P>
<P><SPAN>The study found that antibiotics inhibit competitors at high
concentrations and function as signalling molecules that influence metabolism at
low concentrations. </SPAN></P>
<P><SPAN>"These findings seem to be significant since diatoms, apart from being
the basis of aquatic food-chains, are a popular tool for monitoring past and
present environmental conditions and are commonly used in studies of water
quality," Samiullah Bhat, assistant professor at the Kashmir University’s
department of environment, told <EM>SciDev.Net</EM>.</SPAN></P>
<P><SPAN>The study suggests that investigations on the fate of antibiotics in
antibiotic-polluted and natural environments must consider effects across
trophic levels (position of an organism in a food chain) and particularly,
diatoms, the base of aquatic food webs. </SPAN></P>
<P><A href="http://cs-test.ias.ac.in/cs/php/forthcoming/RA788.pdf"
target=_blank><SPAN><FONT color=#336699>Link to report in <EM>Current
Science</EM>: </FONT></SPAN></A></P></DIV></FONT><BR>
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