13.1.1 Oil and gas drilling

No evidence found (no assessment)

1We have captured no evidence for the following interventions:

• Bury drill cuttings in the seabed rather than leaving them on the seabed surface
• Cease or prohibit oil and gas drilling
• Cease or prohibit the deposit of drill cuttings on the seabed
• Dispose of drill cuttings on land rather than on the seabed
• Limit the thickness of drill cuttings
• Recycle or repurpose fluids used in the drilling process
• Remove drill cuttings after decommissioning
• Set limits for change in sediment particle size during aggregate extraction
• Use water-based muds instead of oil-based muds (drilling fluids) in the drilling process.

13.1.2 General

No evidence found (no assessment)

2We have captured no evidence for the following interventions:

• Bury pipelines instead of surface laying and rock dumping
• Leave pipelines and infrastructure in place following decommissioning
• Limit the amount of stabilisation material used
• Remove pipelines and infrastructure following decommissioning
• Set limits for change in sediment particle size during rock dumping
• Use stabilisation material that can be more easily recovered at decommissioning stage.

13.1.3 Mining, quarrying, and aggregate extraction

Beneficial

Cease or prohibit aggregate extraction

3Seven studies examined the effects of ceasing or prohibiting aggregate extraction on subtidal benthic invertebrate populations. One study was in the English Channel (France), one in the Mediterranean Sea (Italy), one a global study, and four in the North Sea (UK, Belgium).

4COMMUNITY RESPONSE (6 STUDIES)

5Overall community composition (4 studies): One global systematic review found that it took nine months to several decades for overall invertebrate community composition to recover after ceasing aggregate extraction. One before-and-after, site comparison study in the Mediterranean Sea and one of two site comparison studies in the North Sea found that after ceasing aggregate extraction overall invertebrate community composition became more similar to pre-extraction and/or natural site communities.

6Overall richness/diversity (5 studies): Two before-and-after, site comparison studies in the English Channel and the Mediterranean Sea and one of two site comparison studies in the North Sea found that after ceasing aggregate extraction, overall invertebrate species richness and/or diversity became more similar to that of pre-extraction and/or natural sites. The other site comparison found that species richness did not change over time and remained different to that of natural sites. One replicated, site comparison study in the North Sea found that 21 months after ceasing aggregate extraction, invertebrate species richness was similar to that of natural sites.

7Worm community composition (1 study): One before-and-after study in the North Sea found that after ceasing aggregate extraction, nematode worm community composition remained different to the pre-extraction community. Worm richness/diversity (1 study): One before-and-after study in the North Sea found that after ceasing aggregate extraction, nematode worm species richness remained different to pre-extraction richness.

8POPULATION RESPONSE (6 STUDIES)

9Overall abundance (5 studies): Two before-and-after, site comparison studies in the English Channel and the Mediterranean Sea and one of two site comparison studies in the North Sea found that after ceasing aggregate extraction overall invertebrate abundance and/or biomass became more similar to that of pre-extraction and/or natural sites. The other site comparison found that abundance and biomass did not change over time and remained different to that of natural sites. One replicated, site comparison study in the North Sea found that 21 months after ceasing aggregate extraction, invertebrate abundance was similar to that of natural sites.

10Worm abundance (1 study): One before-and-after study in the North Sea found that after ceasing aggregate extraction, nematode worm abundance remained different to pre-extraction abundance.

11Assessment: beneficial (effectiveness 65 %; certainty 60 %; harms 0 %).

12https://www.conservationevidence.com/actions/2070

Unknown effectiveness

Cease or prohibit marine mining

13One study examined the effects of ceasing or prohibiting mining on subtidal benthic invertebrate populations. The study was in the Bering Sea (USA).

14COMMUNITY RESPONSE (1 STUDY)

15Overall community composition (1 study): One site comparison study in the Bering Sea found that following cessation of gold mining, overall invertebrate community composition became similar to that of an unmined site.

16Overall richness/diversity (1 study): One site comparison study in the Bering Sea found that following cessation of gold mining, overall invertebrate richness and diversity became similar to that of an unmined site.

17POPULATION RESPONSE (1 STUDY)

18Overall abundance (1 study): One site comparison study in the Bering Sea found that following cessation of gold mining, overall invertebrate abundance and biomass became similar to that of an unmined site.

19Assessment: unknown effectiveness (effectiveness 70 %; certainty 31 %; harms 0 %).

20https://www.conservationevidence.com/actions/2075

Extract aggregates from a vessel that is moving rather than static

21One study examined the effects of dredging from a vessel that is moving rather than static on subtidal benthic invertebrate populations. The study was in the English Channel (UK).

22COMMUNITY RESPONSE (1 STUDY)

23Overall species richness/diversity (1 study): One site comparison study in the English Channel found that a site where aggregate extraction was undertaken using a moving trailer suction hopper dredger had similar invertebrate species richness and lower diversity compared to a site where extraction occurred using a static suction hopper dredger.

24POPULATION RESPONSE (1 STUDY)

25Overall abundance (1 study): One site comparison study in the English Channel found that a site where aggregate extraction was undertaken using a moving trailer suction hopper dredger had higher abundance of invertebrates compared to a site where extraction occurred using a static suction hopper dredger.

26Assessment: unknown effectiveness (effectiveness 35 %; certainty 20 %; harms 18 %).

27https://www.conservationevidence.com/actions/2071

Leave mining waste (tailings) in place following cessation of disposal operations

28One study examined the effects of leaving mining waste (tailings) in place following cessation of disposal operations on subtidal benthic invertebrate populations. The study was in Auke Bay (USA).

29COMMUNITY RESPONSE (1 STUDY)

30Overall community composition (1 study): One replicated, paired, controlled study in Auke Bay found that plots where mine tailings were left in place had similar invertebrate community composition as plots where tailings had been removed, but both had different communities to plots of natural sediment. Overall richness/diversity (1 study): One replicated, paired, controlled study in Auke Bay found that plots where mine tailings were left in place had similar invertebrate species richness as plots where tailings had been removed, but both had lower richness compared to plots of natural sediment.

31POPULATION RESPONSE (1 STUDY)

32Overall abundance (1 study): One replicated, paired, controlled study in Auke Bay found that plots where mine tailings were left in place had similar invertebrate overall abundance and biomass as plots where tailings had been removed. While plots with and without tailings had similar abundances to plots of natural sediment, their biomasses were higher.

33Assessment: unknown effectiveness (effectiveness 15 %; certainty 25 %; harms 5 %).

34https://www.conservationevidence.com/actions/2077

No evidence found (no assessment)

35We have captured no evidence for the following interventions:

• Cease or prohibit mining waste (tailings) disposal at sea
• Limit, cease, or prohibit sediment discard during aggregate extraction
• Remove discarded sediment material from the seabed following cessation of aggregate extraction.

13.1.4 Renewable energy

No evidence found (no assessment)

36We have captured no evidence for the following interventions:

• Co-locate aquaculture systems with other activities and other infrastructures (such as wind farms) to maximise use of marine space
• Limit the number and/or extent of, or prohibit additional, renewable energy installations in an area.