The dynamics of didymo

Visual Arts:No one could accuse Barrie Cooke of jumping on the environmental bandwagon. As far back as 1988 he painted a major diptych called simply Death of a Lake. It was exhibited the following year at the Kerlin Gallery, addressing in schematic form the destruction of an Irish lake through eutrophication, caused by the excessive proliferation of nutrients in the water, writes Aidan Dunne

In the same exhibition, he showed some of his first paintings of New Zealand, then a place apparently untouched by pollution or other environmental problems. The contrast between the brilliant light and space of New Zealand and the clogged, dying Irish lake was stark and intended.

Fast-forward nearly 20 years to Didymo Paintings, Cooke's current show at the Kerlin Gallery. It focuses exclusively on New Zealand and on a single organism, Didymosphenia geminata, a single-celled microscopic algae. Didymo, known colloquially as "rock snot", is considered a nuisance organism, not directly harmful or poisonous to humans but capable of proliferating at a great rate, producing dense networks of branching stems that clog up stream beds and shallow bodies of water, which is bad for the fish population.

Didymo was once confined to areas of the northern hemisphere, but gradually it started not only to appear in the south but also to grow in greater and greater volumes. Then, in 2004, it appeared in several of the waterways of New Zealand's South Island. Despite efforts at containment, didymo can spread from place to place in a single drop of water, and it has since found its way into many of the rivers that Cooke has come to know as both artist and fisherman, and has now made the leap to the North Island.

There is a certain austerity to Cooke's treatment of this ominous subject. He draws on a limited palette of predominantly muted earth hues and greys, flushed occasionally with orange oxides, subdued pinks and purples, and not a sign of the lush tangles of green or the startlingly clear blues previously associated with his New Zealand paintings. It's not that Cooke is a sentimental environmentalist. He's always taken a pragmatic view of the balance to be struck between nature and culture and the way one can enrich the other. But one would have to say that the didymo paintings suggest that he takes a dim view of the way we're headed.

It could be seen as a paradox that most of the paintings he has made that treat pollution issues are quite beautiful. Algal Growth, from 1990, is probably one of the most beautiful paintings he has ever made. The didymo pictures are beautiful too in their way, but in a sterner, graver register. He is as good as ever at conveying flow with flow: translucent glazes of liquid pigment wash across the canvases in great swathes like water currents. Flow and restraint are the two ideas that shape the dynamics of the images, and we are carried along by the process despite the ominous undertones. They are tough paintings in every sense, and all the better for that.

SCULPTOR CORBAN WALKER, the son of architect Robin Walker and writer and critic Dorothy Walker, has established a real presence on the international stage, and his current Green on Red Gallery show marks something of a triumphant homecoming, following his highly successful exhibition at Pace Wildenstein in New York (where he will continue to be based) earlier this year. He shows a series of geometric glass sculptures and a number of drawings (using AutoCAD software). The seeds of the sculptures are surely in the drawings, even though none of the latter are obvious studies for the three-dimensional pieces.

Walker's work has for some time been linked to a measurement derived from his own height, 129cm, and it is often related to our perception of scale and space, and to the way we negotiate space. The five grid stacks that make up the main part of the show are vertical box-like forms, each composed of a large number of uniform rectilinear strips of two kind of glass: clear float and diamanté.

Every layer of glass is cushioned by an intervening layer of some other transparent material. By varying the positioning of each successive layer of glass strips, precisely calculated angular patterns are formed in the stacks.

Geometric precision on this scale entails an industrial technology, and the pieces were apparently made to order in the Czech Republic. Each work is an amazing physical object, managing to be at once ethereal and very substantial. The patterns generated by the interwoven stacks of glass appear and disappear as you move around the pieces, and the sheer proliferation of individual reflective surfaces, including not only each glass segment but also its bevelled edges, allows the emergence of remarkable visual complexities.

The box-like forms, thus constructed, are architectonic and might almost be scale models of proposed buildings. Yet they are also like individual personages, each with their own character. The sum of these two ideas, of person and building, gives us images of person as building or building as person, and without doubt all of these possibilities are integral to the work. While in one way they are very straightforward things - produced by the application of simple algorithms to a building block methodology - they turn out to be, in the flesh, surprisingly complex. Walker's approach is characterised by precision and formal restraint, and the results are impressive.

Barrie Cooke: Didymo Paintings is at the Kerlin Gallery, Anne's Lane, South Anne Street, Dublin 2, until Dec 22; Corban Walker: Grid Stack Sculptures and Drawings is at the Green on Red Gallery, 26-28 Lombard Street East, Dublin 2, until Dec 22