Sinking of Explorer--Questions Remain

(from eco-page continued)

Last May at a conference of Antarctic Treaty nations, Britain and the United States ominously warned that the tourism situation in the regions was a disaster in the making. Traffic has increased to over 30,000 passengers per year from about 6,000 (1992-1993) and many of these are now coming on large cruise ships. One of these, The Golden Princess, operated by Princess Cruises, carries 2500 passengers and 1200 crew members. The U.S. warned that the treaty nations should "take a hard look at tourism issues now, especially those related to vessel safety, and not await more serious events to spur them to action."

The safety issues relate to poor marine mapping, changeable and extreme weather, lack of rescue capability for large ships, increasing ice-floes from calving of Antarctic shelves, and limited survivability of large hulls if struck by ice.

Mysteries Surround Sinking

Speculation abounds about what breached Explorer's hull and the chain of events that led to her sinking. All the pieces don't yet fit together. Explorer was no ordinary cruise vessel. She was small and agile and designed to handle the seas she was sailing in. She had been here on scores of other sailings. Boasting a double hull, she was supposed to withstand the impact of smaller chunks of floating ice and able to detect and avoid the larger ones. The crew on board was experienced in reading the differences and equipped with state-of-the-art electronic equipment.

Launched in 1969 and first owned by Lindblad Travel, Explorer was built to ferry tourists to Antarctica and give them a chance to experience the natural wonder that has recently been captured by such environmental documentaries as Planet Earth. This particular trip, labeled Spirit of Shackleton, ironically ferried passengers to the site of the famous shipwreck of Ernst Shackleton and Endurance in 1915.

Besides her double hull, M.V. Explorer possessed high-quality sonar and radar; she could even download satellite imagery that could discriminate cloud cover from large, floating bergs. Like the larger ships plying these waters, she also ran with high-beam ice lights after darkness and was manned by ice masters, skilled in reading which ice should be avoided.

"Speed Kills" When It Comes to Antarctic Cruising

She was also prepared for emergencies. According to knowledgeable Antarctic mariners, she followed a well defined protocol for travel under icy conditions. This included speed reduction to 3-5 knots in "band ice"--the type she was transiting at the time of the accident. In the words of one of Explorer's previous captains, Finnish-born, Leif Skog, "In these waters, speed kills." Explorer's protocol also included specifics steps for prompt escape to open seas, signaling to "paired" vessels in the area, and use of auxiliary power in the event that her engine compartment were flooded. (continued on p.2)

Marine Impacts Uncertain After Rosy Initial Reports

PAH Impacts Cause for Concern

Shortly after Explorer sank to the bottom of Bransfield Strait, press reports suggested that marine damage would be minimal. Officials noted that Explorer was carrying light diesel fuel, considered a lesser hazard to marine life than either crude oil or heavier diesel fuels.

Now, it seems that at least a few prominent marine biologists with expertise in cold-climate spills are not quite so ready to dismiss impacts. At issue are the effects of polycyclic aromatic hydrocarbons (PAH's), the light chemical hydrocarbons that constitute a significant portion of light diesel oil.

"Oiling" Not the Only Concern

Historically, scientists studying spills have focused on the toxic effects of crude oil and heavier types of marine diesel, but recent research indicates that PAH's present in lighter fuels can pose a variety of serious problems for marine life. Some PAH's find their way to the surface, while others are dissolve in the water column where they can be ingested by fish, mammals and plankton. A smaller percentage may actually attach to sediment and settle on the bottom, subsequently toxifying filter feeders.

NOAA chemist Dr. John Incardona, whose experience with spills includes work on the effects of the Exxon Valdez, was interviewed by Sydney's Thumb. He notes that "fish and marine birds metabolize these toxics fairly well but shrimp, krill, molluscs, limpets and other marine life are poor metabolizers." They are at risk if they take in water high in PAH's.

Food Web Sensitivity High in Antarctic

Effects on birds and mammals may occur from the reduction of their food source. This is an increased concern when the food web is thin, as it is in Antarctic. As stated in a United Nations Environmental Report, "The marine ecosystem, which contains most of the Antarctic flora and fauna is characterized by short food chains from phytoplankton through krill to large mammals and birds. These short food chains make the Antarctic... very fragile and susceptible to disruption."

Krill a Critical Element in the Web for Whales, Birds, Marine Mammals

The abundance of krill accounts for the fact that whales in the Antarctic are more numerous than at any other place on the planet. Five species graze in the krill-abundant waters, including endangered blue whales that only number about 10,000. Other krill-dependent marine mammals include three species of seals, 20 fish species, squid and seabirds.

The dependence on krill goes deeper, however, as the krill depend on phytoplankton such as algae. Phytoplankton depend in large measure on the presence of sea ice.

Krill and Plankton Sensitive to PAH's

"PAH's from spills (like the current one) pose a potential risk in both the sediment and water column," states Incardona. He is quick to point out that the biological stage of development also makes a difference--"Embryos can be especially sensitive. He adds, "In general, the science (in this area) is still immature." Both he and Woods Hole ecologist, Dr. Hugh Ducklow, caution against over-reacting to the Explorer spill but worry about cumulative effects throughout the marine food chain as more and more cruise ships visit Antarctica. (continued on p.2)