Offshore Industry Thematic Assessment

Ecosystem services impacted by oil and gas

As shown schematically in Figure I.1, each state change/environmental impact associated with the oil and gas industry and carbon dioxide storage will affect a range of different ecosystem services. The specific impact on each ecosystem service is further elaborated in the following text.

Wild fish and other natural aquatic biomass and related raw materials

The discharge of produced water could expose fish and other aquatic biomass to contaminants. This could potentially affect the biomass provisioning service from wild fish and other natural aquatic biomass and community functions such as reproduction. Among the fish species potentially most impacted, at biomarker level, are demersal species such as cod and haddock. Results obtained in studies with field-realistic concentrations indicate that impacts are expected to be modest. The overall risk of produced water discharges exerting an adverse impact on populations of wild fish and other pelagic organisms is therefore expected to be low.

The possible release of oil and chemicals from the disturbance of old cuttings piles, either through decommissioning activities or from bottom trawling after decommissioning, could also expose fish or other aquatic biomass to contaminants. This disturbance results in additional, albeit generally short-term and localised impacts on the water column, and in some (not all) cases could cause contamination of the seabed outside the areas impacted by the original cuttings discharge. Fishing may be able to resume above cuttings piles previously contained in a 500 m safety zone where fishing activities would have been excluded.

It is believed that the physical presence of offshore installations can contribute to biomass production. This ability to contribute to the biomass provisioning service is supported by the intermediate ecosystem service of nursery population and by the habitat refuge provided by the offshore installations, which offer protection against invasive species. This in turn can be assumed to have a relatively small positive effect on the very biomass that makes up the marine food web, i.e., the ecosystem service comprising wild animals, plants, and other biomass.

Noise from seismic surveys can also potentially harm fish, with effects varying greatly from very subtle behavioural changes and avoidance reaction to hearing loss, injury and death in extreme cases.

Ecosystem services impacted by underwater noise associated with the oil and gas industry

For more details on the environmental impacts associated with underwater noise (mainly impulsive noise when it comes to the oil and gas industry) and the resulting impacts on ecosystem services see the Underwater Noise Thematic Assessment .

Wild animals, plants, and other biomass

The construction, operation and decommissioning of pipelines and offshore installations, the discharge of cuttings drilled with water-based mud and disturbance to historic cuttings piles can have a localised and transient negative effect on benthic organisms and could alter the local food web, particularly in aggregations of deep-sea corals and sponges.

Platform lighting and flaring are also known to attract birds, and might cause some mortality in migratory species. The level of impact depends on the location of the platform, the time of year and the prevailing weather conditions, with birds being most frequently attracted during the autumn migration and in poor weather.

Anthropogenic noise introduced to the marine environment can potentially affect marine mammals in various ways and alter prey / food availability. The nature of the effects reviewed range widely, from masking of biological communication and small behavioural reactions to chronic disturbance, injury, and mortality. Noise can also potentially harm fish, with effects varying greatly from very subtle behavioural changes and avoidance reaction to hearing loss, injury, and death in extreme cases.

(Global) climate regulation

Atmospheric emissions from the oil and gas industry have a negative impact on climate regulation services by adding CO₂, methane, and NMVOCs to the atmosphere.

Carbon dioxide capture and storage in geological formations is expected to contribute to reducing CO₂ emissions.

Sediment quality regulation and water quality regulation

The construction, operation and decommissioning of pipelines and offshore installations, the discharge of cuttings drilled with water-based mud and disturbance to historic cuttings piles can have a localised and transient negative effect on benthic organisms. This could potentially affect sediment reworking (bioturbation), filtering organisms and sediment microbial organisms to some extent, which in turn could affect the sediment and water quality regulation service provided by these organisms. The effects on the water column are expected to be local and modest, according to the results of water column monitoring.

Despite the large volumes of produced water discharged, the effects appear to be low and mainly seen at biomarker level. However, the causality between biomarkers and toxic effects and impact at organism and population levels remains to be proven. It should be emphasised that this does not imply that no causal relationships exist between impacts at organism level and impacts at population or ecosystem level. It should only be seen as an indication that there is a lack of evidence and that further investigations are needed to establish whether such relationships exist. They may affect the regulation of both sediment quality and water quality,

Pest control

The potential role of offshore installations (and associated protection material including rock and concrete mattresses) in facilitating the establishment of invasive species by acting as stepping stones is recognised (Fowler et al., 2018). There is also a risk of spreading invasive species when installations are moved to shore after decommissioning. Healthy ecosystems established on and around installations may on the other hand offer protection against invasive species.

For more details on the environmental impacts associated with non-indigenous species and the resulting impacts on ecosystem services, see the Non-Indigenous Species Thematic Assessment .

Nursery population and habitat maintenance

The construction, operation and decommissioning of pipelines and offshore installations and discharges of drill cuttings can have a localised negative impact on megafauna communities, for example by reducing sponge density and diversity. Similarly, seabed disturbance can possibly affect burrowing species and the spawning grounds of bottom spawning fish. This may have the localised effect of reducing habitat maintenance services. Offshore installations can also act as a refuge, providing habitats which offer opportunities for shelter, refuge from predators, and foraging.

Noise from seismic surveys can also possibly negatively affect the breeding areas of marine mammals and fish spawning areas.

Cultural ecosystem services

In relation to the offshore industry, as with most OSPAR pressure-based thematic assessments, assessing cultural ecosystem services and the impacts on them is challenging, due to the fact that cultural ecosystem services rely heavily on personal preferences that will undoubtedly polarise opinions. The very existence of offshore installations and activities close to shore, as well as the risk of accidents, can influence, for example, people’s spiritual connection to the ecosystem.

The physical presence of offshore installations close to shore may affect the wellbeing derived from seeing a pristine seascape, and may adversely affect spiritual, artistic, symbolic, and visual amenity services, in turn affecting the sensory and/or visual perception of the people who benefit from them. However, there are very few offshore installations close to shore (e.g., the eastern Irish Sea, United Kingdom, and the Schleswig-Holstein Wadden Sea, Germany) in the OSPAR Maritime Area.

A number of spills of oil and chemicals from offshore oil and gas operations have been recorded in the OSPAR Maritime Area. Accidental spills of oil and chemicals may have an impact on  marine life. While the nature and extent of the spills from offshore industry to date in the OSPAR Maritime Area have been limited, with a few exceptions the available evidence indicates that the impacts on ecosystem services have also been limited. However, depending on time (season), and location, it is acknowledged that an accidental spill could have a significant effect on cultural ecosystem services, such as ecosystem and species appreciation, and spiritual, artistic, symbolic, and visual amenity services.

Ecosystem services impacted by marine litter associated with the oil and gas industry

For more details on the environmental impacts associated with marine litter and the resulting impacts on ecosystem services see the Marine Litter Thematic Assessment.