9 Other Human Uses and Impacts

Download9 Other Human Uses and Impacts

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Some signs of decreasing oil pollution in the North Sea

Because the North Sea has been designated a Special Area under MARPOL Annex I, the discharge of oil or oily waste is more stringently regulated. Nevertheless, aerial surveillance conducted under the Bonn Agreement suggests that illegal discharges of oil or oily wastes are still occurring Figure 9.3. Limited data are available to quantify how much oil has been spilt in the OSPAR area since 2000 as a result of incidental and illegal discharge. For around 80% of slicks detected using aerial surveillance it is not possible to identify the polluter. This means it is not possible to quantify how many of the slicks are attributable to shipping. Monitoring for the North Sea Ecological Quality Objective (EcoQO) on oiled guillemots suggests that oil pollution at sea has been decreasing.

Figure 9.3 Oil spills detected using aerial surveillance...

Box 9.2 Reduced rate of oiled guillemots indicates decreasing oil pollution in the North Sea

North Sea EcoQO: The average proportion of oiled common guillemots in all winter months (November to April) should be 10% or less of the total found dead or dying in each of 15 areas of the North Sea over a period of at least 5 years.

Guillemots are deep-diving seabirds that are common and widespread throughout the OSPAR area. They are very sensitive to oil pollution. A guillemot will soon die once it is oiled, due to hypothermia and because it is unable to forage and feed. These dead birds wash ashore and the proportion of stranded guillemots that are oiled can be used as an indication of oil pollution in specific areas.

In some parts of the North Sea, over 90% of all stranded common guillemots were oiled until only a few decades ago. Since then rates of oiled birds have declined substantially in most areas. This is thought to be the result of better enforcement of measures, improved awareness and the introduction of port reception facilities for waste oil. However, the EcoQO is achieved in very few parts of the North Sea. Current rates of oiled birds in the North Sea vary significantly from over 50% in the southern North Sea (the Netherlands, Belgium and south-east England) to approximately 4% in Orkney in the northern North Sea.

The main inputs of mineral oil originate from operational discharges from ships, land-based sources and, to a lesser extent, from the offshore oil industry. This partly explains why higher bird oiling rates are seen near busy shipping lanes (southern North Sea, Channel). Accidents at sea are a less frequent source.

Since the discharge of oil or oily mixtures that cause slicks is prohibited in the North Sea, management measures need to focus on the further enforcement of current regulations and raising awareness among operators of vessels to reduce illegal oily discharges.

Evaluation of the EcoQO system for the North Sea

Incidental spills can cause severe damage

Incidents involving spills from ships carrying oil and other hazardous or toxic substances can have severe effects on the marine ecosystem. The effects may be short- or long-term depending on climatic and environmental conditions at the time of the spill and the sensitivity of the area. The Prestige oil spill demonstrates the importance of enforcement of IMO ship standards, appropriate risk response and management of shipping lanes in ecologically sensitive areas to reduce risks of incidents and impacts of oil spills.

Box 9.3 The long-term effects of the Prestige oil spill are not yet known

In 2002, the 26-year old, single-hull tanker Prestige started leaking heavy fuel oil from its 77 000 tonne cargo following an incident 50 km off the Galician coast of northern Spain. The Prestige was towed out to sea. During this operation it broke in two in a storm and sank some 200 km off the coast coming to rest at 3600 m depth on the slopes of the Galicia bank seamount where the wreck continued leaking oil.

An estimated 64 000 tonnes of oil were spilled and polluted the seabed and more than 1000 km of coastline in Spain and France. The immediate area affected off Galicia is an area of ecological importance supporting cold-water coral reefs and deep-sea sponges. The area is also important for the fisheries on which 60% of the Galician population depends.

Initial effects on seabirds were profound. Of the 20 000 oiled birds collected, 75% were dead and few of those collected alive were able to recover. The last remaining Iberian populations of the guillemot were among the worst affected. Given the widespread and long-term impact of the oil spill on the Atlantic coast, estimates suggest that the total number of birds affected was much higher, up to some hundred thousand.

Biomarker measurements in fish showed that large areas of the northern Iberian shelf were affected by oil from the Prestige and that measurable effects decreased over the period 2002 to 2005 indicating a recovery of the water quality. Little is known about the effects of the oil pollution on the deep seabed and its biological communities and the rate of recovery.

Since 1998, a number of incidents have occurred in the OSPAR area involving loss of cargo (e.g. chemicals, timber, containers) and of ships. In most cases, there is limited information to assess the environmental impact of these losses. Improved controls on the securing of cargoes could work to minimise cargo loss.

Air pollution from ships is increasing

Emissions of nitrogen oxides (NOX), SOX and particulate matter from engine exhaust gases and cargo tanks may be carried long distances. Most emissions in EU sea areas are from cargo ships over 500 gross register tonnage. Around 45% of all emissions are from EU-flagged ships and around 20% of emissions are emitted within 12 miles of the coast. The total contribution of NOX from international ship traffic in the North Sea and the Atlantic was 1850 kt in 2007. This is an increase of more than 20% since 1998. Without the strict standards of the revised MARPOL Annex VI adopted in 2008, emissions from international shipping would have been expected to increase substantially. Models predict that by 2020 emissions of sulphur dioxide, NOX and particulate matter from international shipping in all EU seas would have increased from their 2000 levels by 40% (3200 kt), 45% (4800 kt) and 55% (400 kt) per year, respectively Figure 9.4. Implementing the more stringent emissions standards in the amended MARPOL Annex VI will help target air pollution and should be given high priority, particularly in light of the expected increase in ship traffic. Even stricter standards apply in designated NOX and SOX Emission Control Areas. As a SECA, the North Sea currently profits from the more stringent ship fuel regulation for SOX, but this still allows sulphur contents in fuels 15 000 times that of fuel for road vehicles. Moreover, fuel regulations under MARPOL Annex VI address only sulphur and not other polluting substances. This is a gap that needs to be closed. Despite a large amount of information on inputs via the atmosphere, there is limited understanding of the contribution of shipping to environmental impacts.

Ships also emit ozone-depleting gases (e.g. from incinerators and cooling installations) and greenhouse gases from engine exhausts and so contribute to global emissions. A recent IMO study estimates that shipping emitted 1046 million tonnes of carbon dioxide (CO2) globally in 2007, which is 3.3% of total worldwide CO2 emissions in 2007. Most of these emissions (870 million tonnes or 2.7% of global CO2 emissions) have been attributed to international shipping.

The IMO is currently working towards measures to reduce greenhouse gas emissions from shipping. The EU also targets air emissions from shipping through its 2005 Thematic Air Strategy. OSPAR countries support these initiatives.

Illegal discharges and disposal of waste are still occurring

Illegal disposal of waste (litter) from ships can be as detrimental to marine life as oil or chemicals. The greatest danger comes from plastics. Discharge of garbage is regulated through MARPOL Annex V. This prohibits the disposal of plastics anywhere into the sea, and severely restricts discharges of other types of garbage from ships to coastal waters and Special Areas. While shipping is acknowledged as a major source of marine litter it is difficult to quantify the exact amount as many litter items can be attributed to more than one source.

The effects of sewage discharges on water quality and in relation to eutrophication are thought to be minimal provided they comply with MARPOL Annex IV. In the open sea, raw sewage is assimilated through natural bacterial action, but illegal sewage discharges near the coast may be a problem locally.

Lack of data prevents assessment of port waste reception facilities

According to MARPOL, oily ballast and tank washing water, oily bilge water and wastes should be retained on board until they can be delivered to port waste reception facilities. It is difficult to identify improvements brought about by the introduction of port waste reception facilities because there are few data on the amounts and types of wastes handled. Prior to the implementation date of measures there was no reporting system in place and most waste operations in ports are contracted out to private operators which rarely report to port authorities.

TBT losses are expected to cease

There has been much progress towards the phasing out of tributyltin (TBT) Chapter 5. Following the global ban on TBT in anti-fouling systems through the IMO, the release of TBT from ships’ hulls is expected to cease with an associated decline in effects on marine species from TBT. However, losses of TBT substitutes (such as copper and Irgarol) are expected to increase. It has been estimated that ships in the Netherlands’ Exclusive Economic Zone (EEZ) collectively release up to 30 tonnes of copper into the North Sea each year, both in transit and at anchor Figure 9.5. There has been some progress in the development of non-biocidal alternatives to TBT and copper such as self-polishing surfaces and non-sticky paints.

Introductions of non-indigenous species through ballast water continue

Over 160 non-indigenous species have been identified in the OSPAR area, as reported later in this chapter. Some of the main routes for these unintended introductions are through the discharge of ballast water (and the sediments that it carries) and fouling on ships’ hulls. The risk of new species introductions is related to the amount of ballast water discharged, the frequency of ship visits and the match between environmental conditions where ballast water originated and where it is discharged. With increasing ship traffic there is a higher risk that new species will be introduced. Faster ships and shorter journey times mean that organisms have a greater chance of surviving the voyage.

Non-indigenous species can severely affect the structure of ecosystems. For example, the comb jelly (Mnemiopsis leidyi) which feeds on zooplankton and fish eggs was introduced to the Black Sea through ballast water in the 1980s and has been associated with dramatic changes in the pelagic food web and the collapse of commercial anchovy fisheries. The species was first recorded in the Netherlands, Norway and Sweden in 2006. So far, effects on the North Sea trophic structure and on fish stocks are unknown. Milder winters due to climate change are expected to favour its expansion. There is a need for OSPAR countries to ratify and implement the IMO Ballast Water Convention and to assess the risk of new species introductions.

Increasing concern over noise and ship strikes

There are growing concerns over pressure on marine mammal populations due to noise from shipping and the risk of ship strikes, especially along migration routes in Regions I, IV and V. Ship traffic has been shown to be a dominant source of low frequency noise in many, if not most, coastal zones with high ship traffic. It is estimated that there has been an approximate doubling (3 dB increase) of background noise per decade since the 1950s in some sea areas. Commercial shipping is the most probable source of this increase. The development of faster and larger ships, and growth of ship traffic have increased concern about the risks associated with ship strikes. Collisions with ships are known to be fatal for whales, especially larger species, and may be a threat to vulnerable populations in waters with high levels of shipping.

Pressures on the environment are expected to increase

Predictions for shipping for the period to 2020 are difficult, due to confounding economic factors such as oil price and geopolitical issues. However, through-traffic of oil tankers is predicted to increase with higher environmental risks in the busier shipping lanes especially in Region II. Shipping is expected to increase in Region I, where sea-ice retreat and new technology are expected to afford new opportunities for exploiting Arctic resources (hydrocarbons, minerals, fisheries). The most significant threats from Arctic shipping are oil discharges.

With growing ship traffic and vessel size, increasing pressure can be expected from dredging and dumping of sediments from shipping channels, land reclamation and the construction of port facilities. These pressures are mainly concentrated on coastal areas where increasing pressures may conflict with nature conservation objectives for areas of particular ecological value.

Figure 9.4 Percentage of atmospheric deposition of sulphur originating...

Figure 9.5 Estimated losses of TBT and copper from ship coatings...