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Providing evidence to improve practice

Action: Remove or clean-up oil pollution following a spill Subtidal Benthic Invertebrate Conservation

Key messages

Read our guidance on Key messages before continuing

  • One study examined the effects of removing and cleaning-up oil pollution following a spill on subtidal benthic invertebrates. The study was in the Baltic Proper (Sweden).




  • Mollusc condition (1 study): One replicated, controlled, before-and-after study in the Baltic Proper found that after cleaning-up spilled oil using high pressure hot water, crude oil content increased in mussels and did not naturally decrease over time, and was higher than in mussels from an uncleaned contaminated and a non-contaminated site.

Supporting evidence from individual studies


A replicated, controlled, before-and-after study in 1983 in one area of rocky coastline in the northern Baltic Proper, Sweden (Ganning et al. 1983) found that high pressure hot water shore cleaning technique following an oil spill tended to increase crude oil content of blue mussels Mytilus edulis. Results were not statistically tested. After three days, petroleum hydrocarbon content (crude oil) appeared to have increased in mussels from 40 µg/g to 533–657 µg/g, and decreased by only approximately 20–45% (to 290–530 µg/g) after two weeks. These levels tended to be higher than in mussels from an adjacent uncleaned contaminated site (43 µg/g) and mussels from a non-contaminated site (30 µg/g). In summer 1980, crude oil was experimentally spilled on the shore and cleaned. The “cleaned” sea area directly off the shore was fenced with booms, and sorption agents used on the sea surface. Blue mussels (>30 mm in length) collected from a non-contaminated site were placed in 11 net bags (12/bag). A week before cleaning, nine bags were placed within the fenced area, one bag at an uncleaned contaminated site, and one bag at the non-contaminated site, all at 0.5 m depth. One fenced bag was retrieved before cleaning. Three days after cleaning, the bag from the uncleaned contaminated site was retrieved, as well as six bags from the cleaned area. After two weeks, all remaining bags were retrieved. The crude oil content of mussels was measured.

Referenced papers

Please cite as:

Lemasson, A.J., Pettit, L.R., Smith, R.K., and Sutherland, W.J. (2019) Subtidal Benthic Invertebrate Conservation: Global Evidence for the Effects of Interventions. Synopses of Conservation Evidence Series. University of Cambridge, Cambridge, UK.