Routine shipping can be responsible for many types of adverse impacts on the environment. These include water pollution, toxic contamination by antifouling paints, seabird collision and behaviour changes, ship strikes of whales, underwater sound, and air pollution. The latter three are elaborated upon below.
Ship strikes: Records of ship strikes with whales date back to the advent of steam-powered ships. They began to increase, however, between the 1950s and 1970s with the growth in the number and speed of vessels (Laist et al., 2001). While data limitations make it difficult to assess frequency, analysis of stranded whales in the United States from 1975 to 1996 and from 1980 to 2006 suggest ship strikes are responsible for about 15% of observed mortalities, with some species, such as fin whales (33%), more affected than others (Laist et al., 2001; Douglas et al., 2008). Speed is recognized as a critical yet controllable factor in strikes, with most severe and lethal injuries resulting from strikes with vessels travelling at or above 14 knots (Laist et al., 2001). Location of shipping lanes and implementation of marine-protected areas can mitigate the risk of strikes.
Underwater sound: With ships now a dominant and growing source of underwater low-frequency sound (Chapman & Price, 2011), there is an increasing concern over the impact of such noise on any marine life that depends on sound for communication, foraging and predator avoidance (NRC, 2005). Documented responses of fish include: physiological effects such as elevated heart rate, secretion of stress hormones, and increased metabolism and motility (Logan et al., 2015). For marine mammals, impacts include: behavioural changes (avoidance, diving pattern changes); displacement from habitats and masking or interfering with vocalizations made for communication and sensation (which can disrupt feeding) (Jasny et al., 2005; NRC, 2005; Lacy et al., 2015). For the beluga population, strong and prolonged behavioural responses have been linked to the sound of icebreakers some 50 kilometres away (NRC, 2005). In recognition of these impacts, the National Oceanic and Atmospheric Administration in the United States has introduced interim guidance on sound pressure thresholds as it develops comprehensive guidance on sound characteristics likely to cause injury and behavioural disruption (NOAA, 2015).
Air pollution: Although marine shipping is an efficient mode of freight transport, marine engines have been responsible for sizeable quantities of air pollutants, notably PM2.5 (fine particulate matter), SO2 and NOx. This is due to the lack of pollution control requirements and the ships’ use of low-quality, high-sulphur bunker fuels consisting mostly of residual oil (ICCT, 2007; IMO, 2015e). Such pollutants have been shown to affect air quality across entire shipping regions (BC Chamber of Shipping, 2007; Matthias et al., 2010) and can result in higher health risks and costs in port regions where concentrations are highest (Chatzinikolaou et al., 2015). In the Arctic, black carbon particles, which are formed from incomplete fuel combustion and emitted in the form of PM2.5, pose additional ecological and health risks. As the most strongly light-absorbing component of PM black carbon reduces the ability of ice and snow to reflect sunlight, thereby accelerating the retreat of Arctic sea ice (Arctic Council, 2009; EPA, 2015). Air pollution from ships is, however, improving as a result of a 2010 amendment to the International Convention for the Prevention of Pollution from Ships (MARPOL), which has designated significant portions of North American waters (excluding the Arctic) as Emission Control Areas (ECAs). Ships entering ECA waters must now meet new stringent emissions standards for NOx, PM2.5 and SOx levels (EPA, 2010).
Source: Science Advice
