Biosecurity Pathway: Coastal and Marine Infrastructure

Coastal and marine infrastructure includes facilities such as docks, piers, quays, jetties, seawalls, moorings, pontoons and navigational aids. The RAPID project found that an ‘urbanised’ marine environment, typified by man-made structures, can favour marine invasives through factors such as:

• Providing stepping stones for rapid spread.
• Providing substrates of a physical and chemical nature that favour invasives over native species.
• Artificial surfaces are often vertically orientated and therefore shaded (favouring non-native fauna) especially those that have arrived on ship’s hulls.
• Water movement is often slowed and results in accumulation of invasive larvae or spores.
• Antifouling and polluting heavy metals facilitate invasive dominance over native species.
• Fast-growing or opportunistic invasives will establish on new artificial surfaces faster than native species.
• Lack of natural predators/grazers on artificial substrata encourages invasives dominance.
• Eco-engineering can help to reverse some of these factors by providing more naturalised habitats that encourage the return of native species.

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What Damage can Marine Invasives Cause?

Marine invasive species can cause significant damage to waterside infrastructure by organisms attaching themselves to their surfaces causing erosion, weakening, and as a worse case scenario collapse. They can also cause difficulties with the operational aspect of infrastructure such as hydraulic pumps and rams by blocking intakes and moving parts.  The Trumpet tube worm, which is found in the Solent, fouls ships, buoys and other harbour structures by constructing large reef-like structures.  Large tubes (twice the size of those found in natural environments) have been recorded causing operational obstructions which can lead to economic losses through cleaning costs and loss of utility. 

Case Study: Carpet Sea Squirt in Holyhead Marina

The carpet sea squirt Didemnum vexillum was first recorded in north Wales in 2008. Surveys determined it was confined to marina structures. Eradication started in 2009, using isolation and stagnation methods with a chemical accelerant to speed up the process. Further monitoring, eradication and control is still being undertaken and this continued intervention has been successful in containing this species at a low level within the marina. The total cost so far been approximately £800,000. Although numbers have been reduced, it has taken a significant amount of time and resource and highlights the difficulty of control and eradication from marine infrastructure once a species has been introduced.

What Infrastructure is most at Risk?

Marine invasive risk is highest in fully saline environments, where structures without an antifouling coating have been submerged longer than six months and for fixed structures that can only be cleaned in situ. Species can spread when anything is moved, this includes infrastructure especially when it is moved outside of its immediate locality. It also applies to any construction materials, machinery and equipment used to undertake construction or maintenance that is stored in water. For example steel pontoons covered in marine bio-fouling from a fully saline site being moved to a new site would risk introducing marine invasives. Bio-fouling on these structures would require effort to to clean or recoat with anti-fouling paint before installation. 

Operators removing and/or moving in-water infrastructure and equipment (e.g. floating pontoons, buoys, navigational aids) should consider using biosecurity measures, particularly if the movement is outside of the home port/area. Standard good practice is to clean and dry all structures and equipment after moving them from their original location. If cleaning can only occur once the infrastructure/equipment has arrived best practice is it should be carried out in a low-risk area and follow Check Clean Dry protocols. Heavy encrustrations should be scraped off and bagged for landside disposal.

Waterside structures, such as modular marina pontoons, that are designed to make components easy to disassemble and swap on a rotational basis (e.g. every 6-9 months) give an opportunity for the infrastructure to be dried out and kill any marine invasives present.

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Settlement Panels

Settlement panels can be a useful tool to detect and help prevent the spread of marine invasive species on infrastructure at an early stage. The Marine Biological Association have produced a guide on how to make and install these panels. Operators can deploy panels throughout their site to monitor if any marine invasive species are present, resources can then be targeted in any areas that are particularly vulnerable or operationally sensitive. Checking infrastructure for marine invasives during planned inspections and/or maintenance is more cost effective.

What are settlement panels?

These are artificial structures (such as tiles or plates) that are placed in marine environments to attract and monitor the settlement of fouling organisms. The idea is to be able to identify invasive species at an early stage and take measures to prevent their spread. Panels were used in Maryport marina in the Solway Firth for this purpose.

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Biosecurity Actions

Please refer to our Biosecurity Action Plans for measures that you can take regarding waterside infrastructure.

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Coastal and Marine Infrastructure Resources

• GB NNS Guidance on submerged structures
• Monitoring of Marine INNS Using Submerged Settlement Panels, Stranraer Marina and Portpatrick Harbour
• Marine INNS Settlement Panels Instructions for Construction
• Marine Engineering Biosecurity

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