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Providing evidence to improve practice

Action: Extract aggregates from a vessel that is moving rather than static Subtidal Benthic Invertebrate Conservation

Key messages

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  • One 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).

 

COMMUNITY RESPONSE (1 STUDY)

  • Overall 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.

POPULATION RESPONSE (1 STUDY)

  • Overall 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.

Supporting evidence from individual studies

1 

A site comparison study in 2000 of two soft seabed areas in the central English Channel, UK (Boyd & Rees 2003) found that using moving trailer rather than static suction hopper dredgers during aggregate extraction appeared to result in a similar number of invertebrate species, and a lower species diversity, but a higher abundance. Data were not statistically tested. The number of species at trailer- and static-dredged sites were similar (trailer: 20; static: 21). Species diversity was lower at the trailer dredged site than at the static dredged site (data presented as diversity indices). However, abundance of invertebrates was higher at the trailer dredged site (1,617 individuals/sample) compared to the static dredged site (103). In June 2000, sediment samples were collected using a sediment grab (0.1 m2) from two sites at 18–25 m depths. One site had been dredged since 1968 by static suction, while the other had been dredged since 1989 by trailer suction. Invertebrates >0.5 mm were identified and counted from three to four samples/site.

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.