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Habitat Type: Intertidal hard structures - Artificial hard structures
Habitat Type: Intertidal hard structures - Artificial hard structures
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Written by Oliver Lewis
Updated over 5 months ago

The following is a short summary of the habitat type and how to create/enhance it to a "good" condition. For an informed position, please refer to official up-to-date Government guidance or the UK Government's Condition Assessment Sheet.

Artificial hard structures are man-made structures fulfilling a range of functions (for example coastal defences, port, harbour and marina installations, energy infrastructure, aquaculture). They can be made of various hard materials (artificial or natural rock, wood, plastics, metal) that would not normally be found in the area they are being deployed. Examples: seawalls, breakwaters, groynes, jetties, pilings, aquaculture trestles.

How to Create / Enhance to a "Good" condition

⚠️ Important Note

The design and management of coastal habitats will have specific competency requirements which should be demonstrated where these habitats are targeted in the SSM.

There are a set of criteria that are used to judge the condition of this habitat. These are listed below.

Indicator

Good (3 points)

Moderate (2 points)

Poor (1 point)

A

Coastal processes

Coastal processes are functioning naturally. No evidence of human physical modifications which are clearly impacting the habitat.

Artificial structures present, for example groynes that are impeding the natural movement of sediments or water, affecting up to 25% of the habitat.

Artificial structures present, for example groynes that are impeding the natural movement of sediments or water, affecting more than 25% of the habitat.

B

Presence and abundance of invasive non-native species

Not more than one invasive non-native species is ‘Occasional’ on the SACFOR scale or is occupying more than 1% of the habitat. No high-risk species indicative of suboptimal condition present, see Footnote 1 for details.

No invasive non-native species are present above ‘Frequent’ on the SACFOR scale or they occupy between 1-10% of the habitat. No high-risk species indicative of suboptimal condition present, see Footnote 1 for details.

One or more invasive non-native species present at an ‘Abundant’ level on the SACFOR scale; they occupy more than 10% of the habitat; or a high-risk species indicative of suboptimal condition is present – GB Non-native Species Secretariat should be notified, see Footnote 1 for details.

C

Water Quality

No visual evidence of pollution. There are no nuisance algal growths that are likely to be attributable to nutrient enrichment. Consider seasonality of survey timing2.

Visual evidence of low to moderate levels of pollution. Elevated algal growth with increases in cover that may indicate nutrient enrichment. Consider seasonality of survey timing2.

Visual evidence of high algal growth that is indicative of nutrient enrichment. Signs of eutrophication that would impede bird feeding. Consider seasonality of survey timing2.

D

Litter (when examining a beach strandline, mean high water line or intertidal rocky shore)

Following the Marine Conservation Society (MCS) beach litter survey method, the number of items of litter does not exceed 0.0036 m−1 min−1 person−1, equivalent to up to 20 items per person per 100 m per hour. See Footnote 3 for details.

Following the MCS beach litter survey method, the number of items of litter does not exceed 0.0078 m−1 min−1 person−1, equivalent to between 21 and 47 items of litter per person per 100 m per hour. See Footnote 3 for details.

Following the MCS beach litter survey method, the number of items of litter exceeds 0.0078 m−1 min−1 person−1, equivalent to more than 47 items of litter per person per 100 m per hour. See Footnote 3 for details.

E

Amount of colonisation

More than three different communities of flora or fauna present.

Two or three different communities of flora or fauna present.

One or no communities of flora or fauna present.

Condition Assessment Result

TOTAL SCORE 12-15 (75-100%) = GOOD CONDITION

TOTAL SCORE 8-11 (50-75%) = MODERATE CONDITION

TOTAL SCORE 5-7 (0-50%) = POOR CONDITION

Footnotes

Footnote 1 - Abundances estimated using SACFOR scales details available here: JNCC (No date) SACFOR abundance scale used for both littoral and sublittoral taxa from 1990 onwards [online]. Available from:

Use the non-native species list available here:

DEFRA (2022) UK Marine Non-Indigenous Species Priority List (updated 2020) [online]. Available on:

High-risk species indicative of suboptimal condition at time of publication include:
• Didemnum vexillum – Carpet sea squirt
• Hemigrapsus spp. – Asian Shore crabs (H. sanguineus, H. takanoi or H. penicillatus)
• Ficopomatus enigmaticus - Trumpet tube worm
• Corella eumyota – Orange-tipped sea squirt
• Grateloupia turuturu – Devil’s tongue weed, gracie, red menace and red tide
• Schizoporella japonica – Orange ripple bryozoan
Please check for updates of high-risk species.

Footnote 2 - Peak bloom time is July – September

Footnote 3 - Please use the method as set out in Nelms et al (2017) to identify litter m−1 min−1 person−1, which is summarised below:
Collect litter along a linear transect parallel with the strandline, located between the back of the beach and the strandline. The transect should be 100 m long. Assign gathered items of litter to one of 101 item categories, and further classify them into 12 material groups (plastic, polystyrene, rubber, cloth, metal, medical, sanitary, faeces, paper, wood, glass, pottery/ceramic) using MCS classifications. Following this, record and sum all anthropogenic litter items and remove them from the beach. Litter identification guides may be useful, please see Nelms et al (2017) for more details on the method:
NELMS, S.E. ET AL. (2017) Marine anthropogenic litter on British beaches: A 10-year nationwide assessment using citizen science data. Science of The Total Environment [online], 579. Available from:

The indicator thresholds for litter are based on the methods in Van Loon et al (2020), which is guidance developed within the Common Implementation Strategy for the Marine Strategy Framework Directive (MSFD) by the MSFD Technical Group on Marine Litter.
VAN LOON, W. ET AL. (2020). A European Threshold Value and Assessment Method for Macro Litter on Coastlines. EUR 30347 EN, Publications Office of the European Union, Luxembourg. [online] Available from:

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