Jennifer Marohasy

a forum for the discussion of issues concerning the natural environment

Archives for June 2013

Causes of Honey Bee Decline

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bees 4 I visited Hidcote Manor Gardens in Warwickshire earlier today. They have several honey bee hives and a notice board claiming three different reasons for the decline in honey bee colonies across the UK.

“The number of honey bee colonies in the UK has halved in recent years. This is probably due to:
1. The use of agricultural pesticides and chemicals;
2. Varroa mites, blood sucking parasite which seriously weaken or even wipe out whole colonies; and
3. Cold wet summers which prevent bees from leaving the hives to gather food.”

I wonder how much evidence there is for the three possible causes and which might be having the most impact?

The Native Fish Strategy for the Murray Darling Ten Years On (Part 2)

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HUNDREDS of millions of dollars have been spent on fishways, resnagging, riparian revegetation, not to mention the billions for water buyback, all recommendations of the Native Fish Strategy for the Murray Darling Basin 2003-2013 [1]. Those who implemented the program, however, claim no progress, in particular that numbers of Murray cod are still in decline [2]. Murray Cod

Interestingly there has been no review of the program of works over the last ten years against the original recommendations in the strategy. Yet such a review could throw light on why, despite all the money spent, Murray cod numbers are still apparently in decline.

[Read more…] about The Native Fish Strategy for the Murray Darling Ten Years On (Part 2)

The Native Fish Strategy for the Murray Darling Ten Years On (Part 1)

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IT is ten years since the launch of the ‘Native Fish Strategy for the Murray Darling Basin 2003-2013’ [1]. Hundreds of millions of dollars have been spent on the program including to re-snag the main channel of the Murray River with microchip embedded logs, building fish-ways and of course returning hundred of gigalitres of water. All of these initiatives should have helped restore populations of native fish, the objective of The Strategy. Native Fish Strategy Cover

In January I asked the Murray Darling Basin Authority, MDBA, if there would be a formal assessment of the effectiveness of The Strategy ten years on. It was suggested that I consult Edition 34 of RipRap, a publication of the Australian River Restoration Centre dedicated to highlighting many of the achievements of The Strategy. [Read more…] about The Native Fish Strategy for the Murray Darling Ten Years On (Part 1)

Water Levels in the Swan River Estuary: A Personal Observation

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I READ with interest an article in The Fremantle Herald newspaper in which global warming was blamed for rising sea levels, which in turn were said to be submerging the mud flats in the Swan River estuary and thus destroying the habitat of migratory birds.

Reading it, I could not but reflect on my own observations of water levels and on the accretion and erosion of mud banks in the Swan River over my life-time. I have known the river intimately since the early 1940s when as a toddler I first paddled in the waters of Freshwater Bay. Over the years I have swum and fished in, and canoed, rowed and sailed on the river. I have cycled around the riverside paths, explored the river’s shores and bushland, walked my dogs at the river’s edge, and enjoyed the wildlife – some of which (like the river cobbler) seems to have disappeared, while other species (like the black swans) appear to be flourishing. I have known the river from Preston Point at East Fremantle to the Perth Causeway and beyond for over 60 years, and since 1980 I have swum regularly at the old Bicton Baths.

Over all this time I have seen the river rise and fall with the ocean tides, respond to flood waters coming down from the Avon, and fill to its brim with the run-off from heavy rain storms. But I have also seen the Point Walter sand spit so far above the water that it has grown a small-vegetated island. And only last summer there were occasions when the water was so low at Bicton Baths that the bottoms of the swimmers’ ladders were exposed and there were acres of temporarily exposed mudflats west of Alfred Cove and along the Como foreshore.

[Read more…] about Water Levels in the Swan River Estuary: A Personal Observation