Biofouling is the attachment of organisms to submerged surfaces such as ship hulls,
underwater instruments, and marine or freshwater platforms. In this video,
we will examine why biofouling is problematic, the factors that influence biofouling, and then
we will finish with a few innovative engineering solutions to the problem. The cost to the
shipping industry associated with biofouling is in the billions of dollars. Biofouling of
ships results in increased hydrodynamic friction leading to higher ship drag and subsequently
higher fuel requirements. More fuel consumption results in higher carbon dioxide emissions
and more harm to the environment. Furthermore, as ships go around the world, biofouling can result
in the introduction of nonnative species to new environments, which leads to the rise of invasive
species. Time and time again, invasive species have been shown to be detrimental to ecosystems.
Biofouling can also initiate and facilitate the corrosion of metals
thereby increasing the probability of structural failure. The performance of an underwater marine
instrument can be also negatively affected by biofouling because of the increased weight and
sometimes living organisms can interfere with the normal functioning of sensors.
For all these reasons, biofouling is very much an economic and an environmental problem.
There are several thousands of organisms that engage in biofouling. These include but are
not limited to barnacles, zebra mussels, tubeworms, mollusks, microorganisms, plants
and algae. According to the International Maritime Organization (IMO), biofouling begins within hours
of ships being placed in water. Biofouling depends on the design and construction of the ship. In
other words, a ship with a large number of niche areas such as hull appendages and protrusions may
have more fouling. Another factor that contributes to biofouling is the specific operating profile
which may entail operating speed and location of ship when not in use (whether it is in an
estuarine port or open anchorage). The form of ship maintenance is also a factor, in that the
type of antifouling agent used, and hull cleaning practices affect fouling. For more details,
I have placed a link to article discussing biofouling on the International Maritime
Organization website in the description below. So, what can be done about biofouling?
This problem presents an environmental engineering challenge. The traditional engineering approach
was to use the toxicity of metallic compounds to reduce or limit biofouling. The metallic
compounds can be oxides such as cuprous oxide, or organometals like tributyltin
(TBT). Cuprous oxide and TBT were added to paints that were used on ship hulls. However, a ban was
placed on the use of TBT after it was discovered that this chemical was bad for the environment
in that it is toxic to a variety of organisms such as marine mammals and fish that are not involved
in biofouling. TBT is detrimental to fish as it interferes with liver metabolism, causes tail
abnormalities and leads to a slower development rate that is concentration dependent. Hence,
other antifouling agents have been sought out. The use of nontoxic coatings such as silicone coatings
and fluoropolymers prevent or minimize biofouling to an extent. Also, ultrasonic transducers are
effective in small and medium sized boats. It has been demonstrated that the use of plasma pulse
technology is effective against Zebra mussels. All relevant links to materials used to make the
video are in the description below. Please don’t forget to like, subscribe and return next week
for more engaging videos. I post videos just like this every Thursday for environmental scientists
and engineers and for anyone who is interested in the Environment. Thanks for watching! Cheers!