Everyone has seen some sort of human impact in the ocean, from plastic washed up on the beach, to a plankton bloom driven by nutrient pollution, possibly even something as confronting as a fish kill (or even dolphins!). But what about the things you can’t see, say some noise?
Marine noise pollution has again become topical in South Australia, with the announcement that seismic surveys in the waters south and west of Kangaroo Island will begin in 2015. But this raises the question, what do we know about the effects of seismic surveys? The answer is…. not much. There is obviously immense community concern, and I was lucky enough to talk about it on ABC radio today.
For those of you who don’t know, the most common method of seismic surveys in marine waters is to use an array of air guns that are towed below the surface (at say, 8 m depth) behind a ship, firing in a sequence at intervals from seconds to minutes. The sound that is reflected back is then analysed to tell you what is on and under the sea floor, important information if you’re looking to extract resources. These surveys can span hundreds of square kilometres and run for months.
There is some literature on the effect of these surveys, but woefully little, and none in this region. The little information that we do have suggests that the effects will be variable, depending on taxa. Whales and dolphins seem to alter the way they communicate and potentially migration routes or residency patterns, at least in the short term, which is concerning because of the seasonal Blue Whale and Southern Right Whale populations in this region. Fish may become stressed and migrate away from the testing area, which includes important fisheries for species such as the Southern Bluefin Tuna. In contrast, it seems that at least some invertebrates may not be affected. I would reiterate, however, that the evidence in either direction is extremely sparse, which concerns me because this region (South Australia) is a global hotspot for species diversity and endemism.
This is where the discussion collides with another topical issue in Australia – how much information do we need to properly assess applications to develop marine resources, and which activities should we allow in our marine (and terrestrial) environments in the name of “progress”? Although some development and an increase in productivity is good, there is more and more support from the scientific community to make sure we don’t damage our environment beyond repair. I won’t go into detail on this, however, as others have written about this topic in much more depth. But, I note that other countries are taking the issue of marine noise seriously, and discussing it, so why aren’t we?