Extract aggregates from a vessel that is moving rather than static

How is the evidence assessed?
  • Effectiveness
    35%
  • Certainty
    20%
  • Harms
    18%

Study locations

Key messages

  • 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.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

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.

    Study and other actions tested
Please cite as:

Lemasson, A.J., Pettit, L.R., Smith, R.K. & Sutherland, W.J. (2020) Subtidal Benthic Invertebrate Conservation. Pages 635-732 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

Subtidal Benthic Invertebrate Conservation

This Action forms part of the Action Synopsis:

Subtidal Benthic Invertebrate Conservation
Subtidal Benthic Invertebrate Conservation

Subtidal Benthic Invertebrate Conservation - Published 2020

What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

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