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Providing evidence to improve practice

Action: Designate a Marine Protected Area and prohibit dredging Subtidal Benthic Invertebrate Conservation

Key messages

Read our guidance on Key messages before continuing

  • One study examined the effects of prohibiting dredging in marine protected areas on subtidal benthic invertebrates. The study was in the Firth of Lorn (UK).

 

COMMUNITY RESPONSE (1 STUDY)

  • Overall community composition (1 study): One paired, replicated, site comparison study in the Firth of Lorn found that sites inside a protected area that had been prohibiting dredging for approximately 2.5 years had different combined invertebrate and fish community composition compared to unprotected dredged sites.

POPULATION RESPONSE (1 STUDY)

  • Overall abundance (1 study): One paired, replicated, site comparison study in the Firth of Lorn found that sites inside a protected area that had been prohibiting dredging for approximately 2.5 years typically had greater combined cover of bryozoans and hydroids (combined) compared to unprotected dredged sites.

Supporting evidence from individual studies

1 

A paired, replicated, site comparison study in 2009 of nine sites in three areas of sandy and rocky seabed in the Firth of Lorn, Scotland, UK (Boulcott et al. 2014) found that sites inside a protected area that had been prohibiting dredging for approximately 2.5 years typically had greater combined cover of bryozoans and hydroids and different combined invertebrate and fish community composition compared to unprotected dredged sites. In four of six comparisons, sites inside the protected area had higher cover of bryozoans and hydroids compared to dredged sites outside (inside 43 vs outside 34%; 25 vs 15%; 21 vs 10%; 22 vs 9%). In two comparisons, cover was similar inside and outside (19 vs 14%; 52 vs 54%). Community composition varied across the three areas, but within each area was always different in the protected and dredged sites (data presented as graphical analyses). Part of the Firth of Lorn was designated as a Special Area of Conservation in March 2005 and closed to scallop dredging in the boreal spring of 2007. Three areas (25–89 m depth) along the boundary of the closed area were selected. In each area, one site on each side of the boundary (i.e. one inside the closed area, one outside) was surveyed in May and again in July–August 2009. Invertebrates were surveyed using a camera at 30–40 sampling stations/area. For three photographs/station/survey, the combined area covered by erect bryozoans and hydroids was measured, and all animals (24 invertebrate species; combined with one species of skate and one group of fish species) identified and counted.

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.