Quick Dips

Blasting Away

Many small Pacific islands blast boat channels through their reefs to improve transportation, but are worried about the ecological consequences. A two-year study funded by the Ministry of External Relations and Trade has produced some guidelines for environmentally friendly blasting.

Dr Geoff Jones, of Auckland University's Zoology Department, studied the impact of channel construction on local reef structure and marine life. A blasting team dynamiting a channel in Tuvalu recorded the immediate effects of the blast in the area. This was followed up with comparative studies some three months and 14 months later.

"We were surprised in some ways that there turned out to be less negative effects than expected," Jones remarked. The Tuvalu site, and others studied, showed no major long-term problems with the channel construction. The diversity of species was maintained and irregular channel walls provided suitable niches for marine life.

Jones was, however, concerned to see channels being blasted right up into the beach. This leads to erosion from the beach and silting of the channel. He was also opposed to building channels from the sea to internal lagoons. This was done during the war on one island in the Tuvalu group, and Jones hopes it is never done again. "It lowers the water level of the lagoon and kills organisms left beached. It also causes enormous currents which makes it unusable during tide changes," he says.

Jones is pleased to see suggestions of developing marine reserves to compensate for disturbing the reef in channel areas. MERT has published a leaflet outlining Jones's findings and is having this translated into a number of Pacific Island languages.