More cattle deaths from algal toxins

1 July 2012

Four show cows have died, and others possibly affected,  from the effects of cyanobacterial liver toxins in a farm pond in Gwinnett County,  Georgia, USA.  Interesting I see that a decision to treat the algal bloom with algaecide was taken – which will simply release all the toxins into the water en masse.  This is not an action that I would recommend as it merely treats the symptoms, rather than addressing the cause.

Baptiste Lake, near Edmonton, Alberta, has been placed off limits due to the presence of toxic algae.  Health alerts have been issued in Nebraska for Lake Maskenthine and in Washington State (Clark County) for Lacamas Lake.  There is also an algal bloom reported for St Mary’s Pond in Rhode Island.

Not to be outdone, authorities in Middlesex, England, have issued a warning for Pottersburg Creek where positive tests for algal toxins have been recorded.

Diatoms prove their worth yet again

1 July 2012

The diatom Navicula tripunctata, common in eutrophic waters with a high salt content (Photo: Bill Harding)

Diatoms, microscopic algae with cell walls made of silica, have proven to be extremely valuable indicators of water quality.  They also provide indications of the presence of toxic compounds, for example misformed cells as a result of trace metal contamination.

Now, researchers in India have demonstrated that diatoms may also reflect the presence of antibiotics.  Increasing levels of antibiotics in our water resources, originating from either human or animal medications, are an increasing cause for concern.  The research found that

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.’

‘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,’ [said] Samiullah Bhat, assistant professor at the Kashmir University’s department of environment.  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.

Diatoms also act as indicators of climate change and are frequently used to determine the historical nature of water quality in lakes and wetlands – this because the glass-walls of the algal cells do not disappear!