Conservation Evidence strives to be as useful to conservationists as possible. Please take our survey to help the team improve our resource.

Providing evidence to improve practice

Action: Remove and relocate habitat-forming (biogenic) species before onset of impactful activities Subtidal Benthic Invertebrate Conservation

Key messages

Read our guidance on Key messages before continuing

  • One study examined the effects of removing and relocating habitat-forming species before onset of impactful activities on subtidal benthic invertebrates. The study was in the Fal Estuary (UK).

 

COMMUNITY RESPONSE (1 STUDY)

  • Overall community composition (1 study): One replicated, paired, controlled study in the Fal Estuary found that invertebrate community composition was different in plots where maërl bed habitat had been removed and relayed compared to undisturbed maërl after five weeks, but similar after 44 weeks.
  • Overall species richness/diversity (1 study): One replicated, paired, controlled study in the Fal Estuary found that invertebrate species richness was lower in plots where maërl bed habitat had been removed and relayed compared to undisturbed maërl after five weeks, but similar after 44 weeks.

POPULATION RESPONSE (1 STUDY)

  • Overall abundance (1 study): One replicated, paired, controlled study in the Fal Estuary found that invertebrate abundance was different in plots where maërl bed habitat had been removed and relayed compared to undisturbed maërl after five weeks, but similar after 44 weeks.

Supporting evidence from individual studies

1 

A replicated, paired, controlled study in 2012–2013 of 24 plots in six sites of maërl bed in the Fal Estuary, southwest England, UK (Sheehan et al. 2015) found that plots where maërl bed habitat had been temporarily removed then relayed had fewer invertebrate species, reduced abundance, and a different community composition, compared to plots of undisturbed maërl, after five weeks but not after 44 weeks. After five weeks, the removed-relayed plots had fewer species (54 species/core) and lower abundance (155 individuals/core) compared to undisturbed maërl plots (species: 94; abundance: 282), and a different community composition (community data presented at statistical model results and graphical analyses). After 44 weeks, species richness and abundance were similar in the removed-relayed plots (species: 93; abundance: 263) and the undisturbed maërl plots (species: 91; abundance: 178), and community compositions were similar. Dredging of shipping lanes was planned in Falmouth Harbour. This trial study aimed to assess the feasibility of removing and relaying maërl as a mitigation action prior to dredging. Four 5 m2 plots were selected at each of six sites.  One of two treatments was attributed to each plot: maërl removed then relayed, undisturbed maërl (representing natural maërl where no dredging for shipping lane occurred). In September 2012, the top 0.3 m of maërl was dredged from the removed-relayed plots and relayed to its original position 12 h later (to mimic the duration of shipping lane dredging). Five maërl samples were collected using a hand corer (25 cm length, 10 cm diameter) from one plot/treatment/site after five and 44 weeks. Invertebrates associated with maërl habitat (>0.5 mm) were 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.