If the underwater noise levels from boat traffic and industrial activity are too intense they may seriously affect the ability of cetaceans to communicate or to echolocate. Both oil drilling ships and seismic surveys are strongly suspected of having particularly severe effects on cetaceans. For example, in 1992, humpback whales off Newfoundland, Canada, were found with damaged ear structures after underwater blasting was used in constructing oil installations. As the evidence accumulates of severe perturbations in ocean currents caused by global warming, whales cannot be expected to be immune from the consequences. There are also indications that the higher levels of solar radiation caused by the dramatic reduction in stratospheric ozone over the Antarctic has already led to significant declines in phytoplankton production.
Phytoplankton is the basis of the entire food chain in the oceans.
Accidents and disturbance Many of the few remaining northern right whales in the North Atlantic have scars from boat propellers. Collisions with ships are a serious threat to them and other depleted whale populations. Whale watching can provide valuable economic, scientific, and educational benefits, but care is needed to make sure that the additional boat traffic is regulated and the whales protected from harassment.