Understanding the different types of biofouling and its impact on vessel hulls and fleets

BIOFOULING DEFINITION

Biofouling refers to the attachment of algae, plants, microorganisms, or small animals (also known as Invasive Aquatic Species) on damp or submerged surfaces, such as vessel hulls, that serve a mechanical function. Also known as biological fouling, these organisms can be categorised into microfouling and macrofouling or into soft and hard-fouling types. The accumulation of biofouling on vessel hulls is a significant problem

TYPES OF BIOFOULING

Here are some examples, identified as IAS, that contribute to the spread of harmful marine species into our oceans across the world.

Bay barnacle

First recorded as invasive in California and Europe, the bay barnacle is a fast-growing species with high reproductive potential and tolerating wide fluctuations of water salinity and temperature. Able to affect biodiversity, change community structures, and alter the food chain levels.

The species has been introduced to the South-west Atlantic, Caribbean Sea, Atlantic, Baltic Sea, Black Sea, Caspian Sea, North-west Pacific, East Asia Seas; detected but not established in Australia and New Zealand

Asian Paddle Crab

Native to southeast Asia, this swimming crab was first detected in New Zealand in 2000 and currently poses the significant potential to establish itself in Australia. They affect biodiversity through aggressive and competitive predation and also carry diseases like White Spot Syndrome Virus that can impact other crab species, prawns, and lobsters.

Asian green mussel

Occurring mainly throughout the Indo-Pacific and along the Indian coast, the Asian green mussel is robust, tolerating various salinity and temperature ranges. (and reaches high densities)

The species has been introduced to the Caribbean, South Atlantic, South Pacific; detected but not established in far North Queensland, Australia.

Wakame seaweed

Native to cold temperate coastal areas of Korea, Japan, and China, this species is able to colonise rapidly in mild temperature regions. It is therefore able to foul hydro-technical constructions, ships and aquaculture infrastructure.

The species has been introduced to the Mediterranean, North-east Atlantic, South-west Atlantic, North-east Pacific, South-east Australia, New Zealand

European shore crab

Home to the North-east Atlantic and The Baltic Sea, adult specimens are able to withstand salinity fluctuations as well as wide-ranging temperatures. This rugged species can tolerate up to 3 months of starvation but becomes a voracious predator when it is able to feed.

Now the species has been introduced to West Africa (Mauritania to South Africa), the Mediterranean, North-west Atlantic (Delaware to Nova Scotia), South-west Atlantic (Panama to Argentina), East Africa (the Red Sea to South Africa; including Madagascar), North-west Pacific (Japan), North-east Pacific (South-east Alaska to California), East Asian Seas (Burma), Central Indian Ocean (Sri Lanka), South Pacific and South-eastern Australia.

European fan worm

Native to the Mediterranean and northeast Atlantic, this highly fertile species forms dense populations and competes with local filter-feeding organisms for habitat and food.

Now also introduced to the South-west Atlantic, Southern Australia, New Zealand, North-west Pacific.

Colonial tunicate

Home to the North-west Pacific, this species is an aggressive invader that easily reproduces and grows over or smothers existing species.

This species has been introduced to the northeast and north-west Atlantic, north-east Pacific and New Zealand.

North Pacific seastar

A voracious carnivorous feeder native to the North-west Pacific, this highly reproductive species is able to establish large populations in new areas. Forming a serious pest to local species like the endangered spotted handfish as it prays on the fish’s egg masses.

Now introduced North-east Pacific and Southern Australia.

THE EFFECTS OF BIOFOULING ON VESSEL HULLS:

The accumulation of marine biofouling on vessel hulls presents a significant issue to the shipping industry. The build up of biofouling on ship hulls can:

• Increase both the hydrodynamic friction and volume of a vessel, which can increase the drag.
• The increased drag may lead decrease of speed by up to 10%, which may require up to a 40% increase in fuel to counterbalance
• Long-term build-up of fouling can increase the period for dry docking, additional anti-fouling coating replacement and in severe cases, hull repair.

PREVENTING MARINE HITCHHIKERS

Traditional Hull Cleaning Methods:

For many years, hull divers using brushes or karts have been used to clean biofouling and maintain boat bottoms. This method can be seen as dangerous as divers can get lost as a result of murky water due to weather conditions, entanglement or hooking under the vessel and when cleaning around propellers and shafts. In rare cases, this can be fatal.

Brush systems and diver techniques can damage expensive anti-fouling vessel hull coatings and cause grooves which promote the regrowth of slime, algae and barnacles. These methods are harmful to the marine ecosystem as fouling removed during a clean falls into the sea.

As port and IMO (International Maritime Organisation) regulations become increasingly stringent, ship operators and owners are more often required to implement practices to control and manage biofouling to reduce the risk of the transfer of these invasive aquatic species.

Eco-friendly ROV

HullWiper brings a new type of green technology to vessel hulls. As opposed to the traditional methods of hull cleaning, our Remotely Operated Vehicle (ROV) uses high-pressure adjustable seawater jets to dislodge fouling on hulls, eliminating the need for abrasive scrubbing or harsh chemicals that scratch anti-fouling coats. Debris and biofouling are captured, pumped through a filter into an onboard unit and disposed of into dedicated drums onshore for eco-friendly disposal. The ROV can clean day or night, during most weather conditions, and whilst cargo or bunker fuel operations are underway.

With operations bases in Dubai including key locations across the Middle East, Sweden, Norway, Denmark, Singapore, Spain, Egypt, Australia, Panama, and Mauritius, ship owners, and operators can proactively manage the effects of hull fouling on vessel hulls and reduce costs. We’re set to launch our hull cleaning services in Sri Lanka, Korea, South Africa, Chile, and the Bahamas soon!

Get in touch with the HullWiper team at [email protected] to find out what we can do for you and your fleet.

Image Credit: Hamish Lass, BOOP