Michael McCarthy: Nature Studies

Here’s a link to an interesting article in today’s Independent about the state of England’s chalk streams.   They are not, says Environment Editor Michael McCarthy, in a very good condition, pointing to the problems of “diffuse pollution” (a catch-all phrase for all the pollutants that find their way into our rivers across the land, rather than via industrial or sewage effluents).   Principal amongst these is the run-off of agricultural chemicals, particularly nutrients.   This leads, says McCarthy, quoting members of the Salmon and Trout Association, to the growth of “blanket weed”, filamentous algae such as Cladophora glomerata.  Blanket weed smothers the gravel on the river bed which, in turn, makes life difficult for the bugs on which the trout and salmon feed.


The River Wylye at Kingston Deverill: a classic example of an English chalk stream. photographed in May 2010.

All this forms a narrative that has been repeated many times by river users and environmental scientists, including many in the Environment Agency.  The condition even has a name: Chalk Stream Malaise.   The problem is that there is no “smoking gun” to link the run-off to the decline of salmon and trout beyond reasonable doubt.   I had to research the literature on this as part of a study a few years back and was surprised about how little hard evidence I could find.  The circumstantial evidence is strong, so long as you cast your net wider than just English chalk streams, but I could not find one paper in a peer-reviewed literature that demonstrated an unambiguous link between nutrients and blanket weed, or between blanket weed and salmon and trout populations, specifically in chalk streams.   The reality is that there is much else happening in the surrounding catchments, including over-abstraction by water companies, which also affects stream ecology.   Nor are nutrients the sole consequence of increased agricultural production: silt and pesticides also enter the rivers and have their own effects, all of which are difficult to disentangle from one another. The result is a plot of interweaving motives and alibis that would make Hercule Poirot blanch.

See also streams of consciousness, my post from 21 August.


Stream of Consciousness …

A couple of Saturdays ago I picked up a book from the Durham-Palestine Educational Trust’s second-hand book stall in Durham Market.   It was a hardback copy of The Stream by Brian Clarke (Black Swan books, ISBN 978-0552770774), a book I had vaguely registered in my sub-conscious when it was first published in 2002 but never got around to reading.   The Stream is a novel, telling the story of a fictional chalk stream in southern England as an industrial park is developed within the catchment.  It was, I am pleased to say, a very well-spent pound and I would recommend tracking down a copy.

The term “novel” does not really do the book justice.  The perspective swings between human protagonists – the multinational industrialists, local and national politicians and environmental activists – and the life in the stream itself.   Brian Clarke is a fly fisherman so we meet the trout and salmon that live in the stream and are told their stories.  We also meet the mayflies and some of the other invertebrate inhabitants of the stream.   The Stream includes vivid descriptions – perhaps the first in literary history – of trout and mayfly orgasms (perhaps it should be reissued as 50 Shades of Grayling?) and even has some chapters where the algae take centre stage.  The human drama is set against this on-going soap opera in the stream itself.

The human drama, however, is inevitably inter-weaved with the life of the stream itself.   The strength of the book is the way that Clarke manages to do this.   He does not take the sensationalist option; there are no pipes gushing with toxic effluent here.  Rather, there are allusions to slight changes in practice – a decision to take more water from a borehole some distance from the stream itself, a farmer grubbing out hedges to make larger fields that will move the farm into profit – and the subtle chains of causation that are precipitated.  The water table drops … the springs that feed the stream have less water, the bankside vegetation where adult mayflies congregate to breed are lost, and so on.  Finally, the fish themselves struggle to feed and breed and the stream slowly changes its nature.

It is, quite simply, one of the best lay introductions to stream ecology, and their vulnerability to human activities, that I have ever read.   I am becoming increasingly aware that there is a gulf between what environmental professionals want to achieve, and the aspirations of the wider public.  The professionals are often not doing enough to explain their work in terms that the public – who will have to pay for the improvements via higher water charges – can understand.  Books like The Stream are one way that we can do this.