Tanzania concerned about human impact on lakes

29 December 2011

Microcystis, a genus of blue-green algae. Photo: Bill Harding

A study undertaken in Tanzania has provided some insight as to the impacts of humans on lake environments:

An increase in human activity is posing a threat to natural aquatic ecosystems in Tanzania and contributing to environmental damage and ecological changes. Doctoral research carried out by Hezron Emmanuel Nonga shows that agriculture and livestock farming leads to eutrophication in lakes and the proliferation of cyanobacteria which produce microcystins. New information about microcystins and other mycotoxins in Tanzanian lakes is useful for appraising the risk linked to drinking water and edible fish, which in turn affects the health of both humans and animals.

Owasco Lake, one of the Finger Lakes in New York, has received an unwanted load of sewage:

An equipment breakdown this spring at the Groton Wastewater Treatment Plant sent scores of pounds of extra phosphorus into Owasco Lake, a problem the plant manager and the DEC said is now under control.

At the end of May, a mixer fan in one of the plant’s two 300,000 gallon tanks broke, putting the facility on half capacity and leading to the discharge of wastewater that had been only partially treated.

From Owasco to Oswego (pay attention now, Osewgo Lake is in Oregon (where the pine trees come from!):

Runoff from phosphorus fertilizers can cause the growth of harmful algae in the area’s stormwater detention systems.

While winter’s chill has driven thoughts of spring from most people’s minds, some in Oswego are already thinking about warmer times ahead.

And when it comes to future lawn and garden maintenance, Oswegoland Park District Executive Director Bill McAdam hopes residents will think twice before using fertilizers containing phosphorus. McAdam said runoff from phosphorus fertilizers can cause the growth of harmful algae in the area’s stormwater detention systems.

“The water turns that icky green color which then in turn sucks more oxygen out of the water and has a detrimental effect on the fish,” he said.

Ridding a pond of the algae can also be costly to property owners, includng public bodies. Already, McAdam said several states have enacted a ban on lawn fertilizers containing phosphorus, including Maine and Wisconsin.

In Oz, the Gippsland Lakes are at last off the danger list:

Authorities have deemed fish caught in the algae-affected Gippsland Lakes, south-east of Melbourne, are safe to eat if the gills and guts are removed.

Commercial fishers are back out on the lakes after authorities lifted a ban on eating the fish, caused by an algae bloom.

The ban started on December 16 after the Health Department determined the algae was causing high levels of toxicity in fish.

Tests have since found the toxins are concentrated in the innards of a fish, not in the flesh, and are safe to eat if the guts and gills are removed.

The news is not as good for Nowra Lake in New South Wales (note the “end of pipe” management options and the wishful “remove the algae permanently” hope – Australian water quality managers are usually better informed on their options):

Nowra’s Marriot Lake will not be cleaned up until after the New Year after the appearance of yetanother algal bloom.

Shoalhaven Council has been looking for a way to permanently remove the algae from the lake and prevent it from reappearing, however, there is the danger that any chemicals used on the lake could damage the wildlife.

Of course there is a way to reduce the algal bloom intensity: just get the nutrient levels down!

Jennifer Klug has been given an award for her work on eutrophication in Lake Lilli. Nice to see the locals recognizing people who try to make a difference.

Jennifer Klug (Source: Fairfield University).

Lake Lillinonah, Connecticut’s second largest lake, is one of the state’s premier fishing holes, a fact not lost on both savvy anglers and the many bald eagles that roost along its 45 miles of serene shoreline from Southbury to New Milford.

Unfortunately, “Lake Lilli” is also widely known for its overabundance of algae blooms, which can make some of the lake’s surface look like it’s covered in pea soup in late summer, leaving swimmers and water-skiers looking elsewhere for fun.

That’s where Jen Klug, Ph.D., associate professor of biology for Fairfield University, comes in. A Newtown, resident, Dr. Klug has spent the last eight years monitoring and studying the lake’s algae blooms, which could threaten the bass and other wildlife if they grow unchecked.

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