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Providing evidence to improve practice

Action: Designate a Marine Protected Area and install physical barriers to prevent trawling Subtidal Benthic Invertebrate Conservation

Key messages

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  • One study examined the effects of installing physical barriers to prevent trawling in a protected area on subtidal benthic invertebrate populations. The study was in the South China Sea (Hong Kong).

 

COMMUNITY RESPONSE (1 STUDY)

  • Worm community composition (1 study): One replicated, site comparison study in the South China Sea found that sites in a protected area where physical barriers were installed to prevent trawling had a different community composition of nematode worms compared to nearby unprotected fished sites, after up to two years.
  • Worm species richness/diversity (1 study): One replicated, site comparison study in the South China Sea found that sites in a protected area where physical barriers were installed to prevent trawling had similar diversity and species richness of nematode worms to nearby unprotected fished sites, after up to two years.

POPULATION RESPONSE (1 STUDY)

  • Overall abundance (1 study): One replicated, site comparison study in the South China Sea found that sites in a protected area where physical barriers were installed to prevent trawling had fewer small invertebrates compared to nearby unprotected fished sites, after up to two years.
  • Worm abundance (1 study): One replicated, site comparison study in the South China Sea found that sites in a protected area where physical barriers were installed to prevent trawling had fewer nematode worms compared to nearby unprotected fished sites, after up to two years.

Supporting evidence from individual studies

1 

A replicated, site comparison study in 2007–2008 of four soft seabed sites in the South China Sea, Hong Kong (Liu et al. 2011) found that sites inside a marine protected area where barriers were deployed to prevent trawling had fewer small invertebrates and nematode worms, a different nematode community composition, but similar nematode diversity and species richness, compared to adjacent unprotected fished sites, after up to two years. Invertebrate abundance was lower in the protected area (198 individuals/10 cm2), compared to the unprotected fished area (290 individuals/10 cm2). Nematode abundance was lower in the protected area (183 individuals/10 cm2), compared to the unprotected fished area (280 individuals/10 cm2). Nematode community was different inside and outside the protected area (community data reported as a graphical analysis). Nematode diversity (reported as diversity indices) and species richness were typically similar in the protected (ranging from 10 to 39 species) and unprotected areas (ranging from 20 to 33 species). Increased abundances were associated with increased sediment disturbance from trawling. In 2006, a 12 km2 area was designated as a marine protected area and trawling discouraged by placing artificial reefs and concrete blocks with steel spikes inside and along the boundary of the area. Two sites inside and two outside the protected area were sampled at quarterly intervals between April 2007 and January 2008 at 20 m depth using a sediment grab (0.1 m2). Small invertebrates (0.038–0.5 mm) were extracted and counted. Nematode worms were identified and counted. In the sites outside the protected area, one bottom trawl was conducted prior to each sampling.

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.