The day-to-day impacts of shipping on the environment are caused by ordinary operational discharges and of organotin compounds from anti-fouling systems. To protect ships against corrosion, zinc anodes are used in addition to special paint. If zinc anodes are used in ballast tanks, the zinc content in the water discharged may exceed the tolerance limits of fish eggs and larvae by a factor of 10 to 100. This may have local impacts in areas where ballast water is discharged, although no such impacts have been registered so far.
Emissions due to normal shipping operations are thought to have negligible or small effects on seabirds (Christensen-Dalsgaard et al., 2008). Individual birds may be affected by the small amounts of oil floating on the sea, but probably not to a degree noticeable at the population level. Chronic oil pollution must be considered as the most serious potential problem with regard to the possible consequences of ship traffic (without taking acute spillages into account). If large amounts of oil are released illegally, this may have serious consequences for seabirds. Chronic oil pollution along the Labrador and Newfoundland coast has annual impacts on seabird mortality at similar levels as the Exxon Valdez accident (Wiese et al., 2004).
Introduction of alien species
Today, the introduction of alien species through ballast water is considered to be one of the most serious threats to biodiversity in marine ecosystems. Thus, vessels from other parts of the world where the climate and ecological conditions are similar to those in the Barents Sea area may represent a great risk. However, we know very little about impacts of introduced species in ballast water in the Barents Sea. Alien species, particularly benthic species and species with a benthic stage in the life cycle, may also be introduced as fouling on ships’ hulls.
Other impacts from ship transport
Ship transport poses risks to some marine mammals, particularly near the coast in the Barents Region. White Sea harp seals are currently experiencing considerable pup mortality due to shipping, when vessels break through the ice in whelping patches (Vorontsova et al., 2008). These sorts of issues are likely to represent increased risks to marine mammals in the Barents Region as retracting sea ice permits a longer shipping season, and increased potential for industrial activity.