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Aquaculture Biosecurity Challenges in the Light of the Ballast Water Management Convention


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Shipping plays a crucial role in supporting global trade, including the transport of products from the aquaculture industry. However, ships may also unintentionally transport invasive species and pathogens in their ballast water which pose biosecurity risks for aquaculture. The Ballast Water Management Convention was developed to manage the biosecurity risks posed by ballast water and has entered into force in September 2017. The management measures and technologies arising from the convention provide some solutions and opportunities for the aquaculture industry. Among these is the potential transfer of treatment technologies between shipping and aquaculture in order to deal with bio-invasion and biosecurity. However, there are residual weaknesses in the regulatory regimes for ballast water management which may reveal a continuous risk from shipping to the aquaculture industry. Gaps include knowledge and management of other aquatic bacteria or viruses that could cause outbreaks in the aquaculture industry and threaten food security and human health. Solutions include focused risk assessments for aquaculture and regional collaboration.
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Asian Fisheries Science 31S (2018): 168181
Asian Fisheries Society
ISSN 0116-6514
E-ISSN 2071-3720
Aquaculture Biosecurity Challenges in the Light of the Ballast
Water Management Convention
1DHI Water & Environment, Singapore
2SGS Testing & Control Services, Singapore
3Tropical Marine Science Institute National University of Singapore, Singapore
4 DairyNZ, Otago, New Zealand
5 Singapore ETH Centre, ETH-Zurich, Singapore
Shipping plays a crucial role in supporting global trade, including the transport of products
from the aquaculture industry. However, ships may also unintentionally transport invasive species
and pathogens in their ballast water which pose biosecurity risks for aquaculture. The Ballast Water
Management Convention was developed to manage the biosecurity risks posed by ballast water and
has entered into force in September 2017. The management measures and technologies arising from
the convention provide some solutions and opportunities for the aquaculture industry. Among these
is the potential transfer of treatment technologies between shipping and aquaculture in order to deal
with bio-invasion and biosecurity. However, there are residual weaknesses in the regulatory regimes
for ballast water management which may reveal a continuous risk from shipping to the aquaculture
industry. Gaps include knowledge and management of other aquatic bacteria or viruses that could
cause outbreaks in the aquaculture industry and threaten food security and human health. Solutions
include focused risk assessments for aquaculture and regional collaboration.
Keywords: compliance, invasive species, pathogens, regulation, shipping, water treatment
Shipping is one of the key stakeholders of global trade and plays a crucial role in transporting
more than 90 % of all international goods across the globe (Wan et al. 2016). Altogether, there are
more than 50 000 merchant ships sailing the world’s oceans, and this represents a global tonnage of
600 million tonnes (Globallast 2016).
*Corresponding author. E-mail address:
169 Asian Fisheries Science 31S (2018): 168181
Naturally, this global trade also includes the trade of fish meals, animal feeds and aquaculture
products. Nearly 40 % of fish output (wild caught and farmed) is traded internationally, making
seafood one of the most extensively traded commodities in the world. It is considered that exports of
fish products from developing countries represent a larger proportion of total exports compared to
that of tropical beverages, nuts, spices, cotton and sugar combined (Asche and Khatun 2006). In this
respect, the aquaculture industry is dependent on the capacity of shipping to transport these goods
and products, and at reasonable prices. There is however, another linkage between these two
industries, and that is the biosecurity risks posed by the global movement of ships which may
unintentionally transport pathogens with the potential to affect aquaculture. There is a need to
understand and evaluate how these two industries are inherently connected. In this paper, we offer
an overview of the existing regulatory regimes developed by the member states participating in the
global objectives of the International Maritime Organization (IMO) as well as the United States of
America's Coast Guard to decrease the risks of transfer of pathogens. We focus on the management
tools and frameworks dealing with the risks associated with the transport of ballast water and
eventually reflect on the potential transfer of technologies between shipping and aquaculture in
order to deal with bio-invasion and biosecurity.
History of Bio-Invasions Associated with Shipping
Invasive species are viewed as a major threat to aquatic ecosystems and have been reported to
affect global economies and societies (Carlton 2002; Occhipinti-Ambrogi and Savini 2003). In the
United States of America alone, the impact of aquatic invasive species is estimated to range between
millions and billions of dollars annually (Lovell et al. 2006). The shipping industry has been
identified as a major source of transport of exogenous species across ecosystems, with about a third
of the introductions due to fouling on ships' hulls and another third due to ballast water exchanges
(Gollasch 2006, 2007; Galil et al. 2014). Aquaculture as a whole represents the other major source
of invasions, and approaches to diminish these risks have been proposed (Leung and Dudgeon
2008). The impacts of shipping on the occurrence of biological invasions was recognized over 100
years ago, when the first suggested introduction of a non-indigenous marine species, the diatom
Odontella sinensis, known from the tropical and subtropical coasts of the Indo-Pacific, was reported
in European waters where it produced dense plankton blooms in the North Sea and more recently in
the Baltic Sea (Olenina et al. 2009). Unlikely to have been carried by ocean currents from such
distant seas, Ostenfeld (1908) suggested that this species was introduced by shipping as part of the
biofouling community on a vessel’s hull or discharged with the water or sediments contained in
ships’ ballast tanks. Later, other phytoplankton species such as toxic dinoflagellates were also
demonstrated to be transported via ballast water (Hallegraeff and Bolch 1992). This is also the case
for species of zooplankton, for which Acartia tonsa, for example, was first described in Europe in
1927 and for which haplotypes were found in the Baltic Sea that were 100 % similar to specimens
from Rhodes Island, United States of America (Rémy 1927; Drillet et al. 2008).
Asian Fisheries Science 31S (2018): 168181 170
Fortunately, not all species can survive the transfer through ecosystems in tanks or on ship
hulls; and those surviving the transfer may not become invasive. In order to be successful at
invading a new area, an exogenous species must first be pumped into ballast water tanks or
colonialize the hull of a ship; it must survive transportation to a new location where it would be
either discharged or would release offspring; then it must be able to colonize the new ecosystem and
establish itself to the point that it becomes considered invasive (Carlton 1985; Smith et al. 1999).
There is a broad principle that estimates that only 10 % of all potential invasive species make it to
the next step of this succession (Williamson et al. 1986; Williamson and Fitter 1996; Boudouresque
and Verlaque 2002; Coutts et al. 2010).
However, aquaculture pathogens are particularly of concern because they usually remain
unnoticed until disease outbreaks are recognized, by which point they have already affected a
multibillion dollar industry (Minchin 2007; FAO 2016). Furthermore, there is clear evidence of the
role of ships in spreading protozoans, bacteria and viruses to different world regions in ballast water
and sediments, as well as in biofilms on ballast tank surfaces (Drake et al. 2007) and ship hulls
(Sylvester et al. 2011). As most aquaculture activities are usually in the vicinity of ports and quite
often create nutrient-rich sediments, there is a possibility of transfer of pathogens from ballast water
to aquaculture facilities. For example, the human pathogen Vibrio cholerae was released by ships’
ballast waters in Mobile Bay, United States of America in 1994 and led to the poisoning of oysters,
which were subsequently taken off the market for a period of time, leading to significant economic
losses (McCarthy and Khambaty 1994). Other famous cases include the spread of the parasite
Bonamia ostreae or bonamiosis along the south coast of Britain, potentially via barges fouled with
infected native oysters (Ostrea edulis) (Howard 1994). Vertical transmission of certain molluscan
diseases such as Perkinsis spp. have also been observed as a result of the fouling of ships’ hulls by
contaminated commercial molluscs (Gollasch 2002). Contamination via biofouling communities has
also been held responsible for the spread of amoebic gill disease (Neoparamoeba pemaquidensis) in
cultured Atlantic salmon (Tan et al. 2002).
Ballast Water as a Vector of Concern
As previously mentioned, global trade is heavily dependent on the import or export of raw
materials such as wood products, grains, coal, iron and other minerals. These commodities are
transported across the oceans in specialized bulk carrier ships in one direction, taking on ballast
water for their return voyages when not carrying goods. Although ship owners try to transfer goods
during voyages from and to different ports to avoid travelling empty, there is often a need to balance
cargoes in weight. Other ship types such as container vessels may adapt their ballasting regime to
the amount and type of cargo in each port visited through a route across the globe. Ballast water is
used in ships as a means to stabilize the ship when no or limited cargo is present (Fig. 1). It is an
important aspect of the routine activities on-board and ensures that the ship and the crew are safe.
Because of this vital role, ships will to continue to use ballast water for many more decades, if not
171 Asian Fisheries Science 31S (2018): 168181
Fig. 1. Cross-section of ships showing ballast tanks and ballast water cycle. (Adapted from GloBallast 2016).
Because of the consequences of bio-invasions generated by the exchange of ballast water
across ecosystems, this topic has received quite a bit of attention in the last decades, and much
research on organisms transferred through ballast water or its sediments has been carried out
(Carlton and Geller 1993; Eno et al. 1997; Ruiz et al. 1997; Briski et al. 2011; Seebens et al. 2013).
Ballast water is estimated to be responsible for the transfer of between 7 000 and 10 000 different
species of marine microbes, plants and animals globally, each day (Carlton 1999).
The annual amount of ballast water transported is large; estimated to be between 3.5 billion
tonnes (Endresen et al. 2004) and 10 billion tonnes (Gollasch 1998). Large ships such as bulk
carriers may pump 10 000 to 20 000 m3 of water per hour (GloBallast 2016). Relating this to a
traditional pond size in the Asian shrimp industry, this would equate to 13 shrimp ponds per hour.
The International Maritime Organization (IMO), with its headquarters in London, has come up with
a list of the ten most unwanted marine species carried by ballast water (Table 1).
Asian Fisheries Science 31S (2018): 168181 172
Table 1. The International Maritime Organization's top-ten most unwanted species. Note that this list still omits viruses
and bacteria, which may be more problematic for aquaculture.
Vibrio cholerae (various strains)
Cladoceran water flea
Cercopagis pengoi
Mitten crab
Eriocheir sinensis
Toxic algae
Red/brown/green tides of various species
Round goby
Neogobius melanostomus
North American comb jelly
Mnemiopsis leidyi
North Pacific seastar
Asterias amurensis
Zebra mussel
Dreissena polymorpha
Asian kelp
Undaria pinnatifida
European green crab
Carcinus maenas
Ballast Water Management
To address the issue of biological invasions through shipping, the IMO has worked towards
the development of a regulatory regime which provides measures to protect the environment from
bio-invasions. This includes the Guidelines for the control and management of ships' biofouling to
minimize the transfer of invasive aquatic species (Biofouling Guidelines, resolution MEPC.207
(62)), which are intended to provide a globally consistent approach to the management of
In 1991, the Marine Environment Protection Committee (MEPC) of the IMO adopted the
International guidelines for preventing the introduction of unwanted aquatic organisms and
pathogens from ships' ballast water and sediment discharges through the resolution MEPC.50 (31).
A few years later in 1997, the developments and discussion generated from these first guidelines
supported the IMO-MEPC in adopting the Guidelines for the control and management of ships’
ballast water to minimize the transfer of harmful aquatic organisms and pathogen through the
resolution A 868(20). Eventually, the International Convention for the Control and Management of
Ships’ Ballast Water and Sediments was adopted in 2004 through the resolution MEPC.253 (67).
This last resolution is also referred to as the Ballast Water Management Convention, or BWMC. As
a convention and not a guideline, this last is legally binding. The convention was to enter into force
exactly one year after at least 30 countries representing 35 % of the world merchant shipping
tonnage have ratified it (Article 18). In order to prepare for the convention to enter into force, there
has been a large amount of work carried out by IMO (Fig. 2). To support the preparation of
stakeholders to the entry into force of the convention, the GEF-UNDP-IMO GloBallast Partnerships
Programme was developed (Globallast 2016). This programme was initiated in late 2007 and was
intended to be finished in 2012, but has been extended until the spring of 2017.
173 Asian Fisheries Science 31S (2018): 168181
Following the ratification of the convention by Finland in September 2016, the BWMC has
entered into force in September 2017. The world merchant fleet is now bonded to the convention.
This entry into force will ensure that a good part of the bio-invasion risks associated with ballast
water exchanges will be managed and reduced.
Fig. 2. Developments associated with the preparation of the entry into force of the Ballast Water Management
Convention. (Adapted from Drillet (2016)). BWMC = Ballast Water Management Convention, BWMS TA = Ballast
Water Management System Type Approval, PSC = Port State Control.
In short, from September 2017 to 2024, more and more ships will have to comply with the
convention in that they will have to ensure that every single ship will have a ship-specific Ballast
Water Management Plan (BWMP) describing how the ship is managing its ballast water and its
sediments, an International Ballast Water Management Certificate (delivered by a flag state,
eventually through a recognized organization), and a Ballast Water Record Book, where every
single ballasting or de-ballasting event will have to be reported. The BWMP will in most cases
include the treatment of ballast water using a Ballast Water Management System (BWMS) which
must receive a Type Approval by an administration (see following paragraphs). However, ship(s) on
short-sea voyage(s) between specified ports or locations across international borders may be granted
an exemption from applying ballast water management systems under the convention (regulation A-
4), if it is decided that the risk of transfer of invasive species is acceptable. A risk assessment should
be carried out and Guideline G7 details the recommended process for this. The regulations allow an
exemption to be granted for multiple ships and voyages between specified ports and locations,
thereby supporting a regional approach to exemption through the identification of a “Same Risk
Area” or SRA (Stuer-Lauridsen et al 2018).
Asian Fisheries Science 31S (2018): 168181 174
Draft guidelines for the risk assessment of a SRA were proposed (Saunders et al. 2016 and
references therein) and were accepted by the MEPC in 2017. Nevertheless, while short-sea shipping
may have a possibility to be exempted of using BWMS, it is expected that most ships will have to fit
or retro-fit a system type approved to treat water.
The Type Approval of Ballast Water Management Systems
In line with the convention, all equipment on-board a ship is type-approved and proven to
work according to a strict set of specifications; BWMS therefore have also to be tested. There are to
date 59 type-approved systems under the IMO umbrella, and the guidelines used for carrying out
these evaluations are referred to as the G8 and G9 guidelines. Globally, there are at least 19
organizations involved in testing BWMS, and these are represented by the NGO Global TestNet
(Global TestNet, 2018).
This network was initially supported through the work of The GEF-UNDP-IMO GloBallast
Partnerships Programme and became independent from this support when signing the Busan
Memorandum of Understanding (MoU) in 2013. The Global TestNet aims to increase levels of
standardization, transparency and openness in testing BWMS. Typically, the BWMS are tested
using volumes of 250 m3 of water through the use of pumps; the water is stored in tanks before
testing the capacity of the BWMS to ensure a valid discharge through a stringent biological
evaluation by an independent laboratory (Fig. 3).
Fig. 3. Top left: the DHI ballast water technology and innovation centre in Singapore, bottom left: cultures of standard
test organisms (Tetraselmis sp.); right: inside a 250 m3 retention tank used for mimicking ballast water transported
during a ship’s voyage.
175 Asian Fisheries Science 31S (2018): 168181
Similar to the BWMC of the IMO, the United States of America has implemented its own
regulation to deal with the risk management of biological invasions through ballast water. This is
commonly referred as the United States Coast Guard (USCG) regulations, and they became
effective in June 2012 (U.S. Coast Guard. Standards for Living Organisms in Ships’ Ballast Water
Discharged in U.S. Waters. 33 CFR Part 151 and 46 CFR Part 162). Being a national regulation, this
applies only to ships discharging ballast water in United States waters. The discharge standard of
both the USCG and the IMO regulations is similar, and a ship may discharge water containing less
than the following number of organisms:
a) 10 viable organisms per m3 >50 μm;
b) 10 viable organisms per mL between 10 and 50 μm
c) one cfu of Vibrio cholerae per 100 mL or one cfu per 1 g (wet weight) zooplankton;
d) 250 cfu of Escherichia coli per 100 mL; and
e) 100 cfu of intestinal enterococci per 100 mL.
There are some differences between the two regulations, for example, in terms of the
definition of "viability": the USCG regulation considers that an organism discharged in its territorial
waters should be dead, whereas the IMO considers that non-viable organisms should not be taken
into account in the discharge assessment, because of their incapacity to reproduce. Other differences
between the IMO and USCG regulations exist in the guidelines and protocols describing the testing
procedures for granting a type-approval to a BWMS. To date, the USCG has only approved six
systems and more applications are being processed. Yet, this this is seen as a bottleneck by the
shipping industry, who must fit systems onboard ships as soon as possible. The G8 guidelines which
are used as a basis for the testing of BWMS under the IMO umbrella initially presented limitations
because they were developed before any BWMS was ever tested. Some of these limitations have
been raised to the IMO-MEPC, as well as in peer-reviewed papers (Miller et al. 2011; Drillet et al.
2013). In light of these issues, the MEPC has re-opened the G8 guidelines for review and a new
version with a set of more stringent testing obligations was submitted to MEPC, and approved in
October 2016. The revised testing Guidelines G8 are now mandatory (as a code) and this ensures
that no new type-approval will be given to systems tested under the old G8 guidelines after 2018;
and all systems installed on ships after 2020 will be required to be tested under the revised G8
guidelines (the Code). This revision by IMO ensures that the convention will become better at
reaching its objectives of decreasing the rates of bio-invasions.
Remaining Weaknesses, Biosecurity Challenges and Gaps
Although the BWMC provides an important tool for managing the environmental risks from
ships’ ballast water, some stakeholders still consider that the 27 years taken to achieve this has been
too long, that too few states representing the highest tonnage have signed up to the Convention
(Wan et al. 2016) and that gaps remain in the protection measures (Drillet et al. 2016).
Asian Fisheries Science 31S (2018): 168181 176
The BWMC is an international agreement and therefore only regulates ships exchanging
ballast water across international borders, not wholly within domestic waters. The regulation
applying to ships travelling solely in a single country’s water are specific to that particular country.
The convention therefore creates a scenario where exchange of ballast water between distant ports
of a single country may be unregulated (if not regulated at the national level), while the discharge of
ballast water between ports in neighbouring countries (for example across a strait) is subject to the
regulations set out by the BWMC despite the expected higher ecosystem similarity at the local scale.
For example, in the Southeast Asian context, a ship ballasting on the west coast of Thailand in
the Andaman Sea and travelling to and deballasting in a Thai port in the Gulf of Thailand (ca. 1 500
nautical miles away) would not require an application under the BWMC, while a ship sailing from
Singapore to the island of Pulau Batam (Indonesia), less than 10 nautical miles away, would have to
comply with the convention. This is both biologically and administratively unsound (Stuer-
Lauridsen and Overgaard 2014; Saunders et al. 2016). Currently the only way to resolve such issues
is voluntarily through regional sea approaches and working groups such as the Helsinki Commission
(HELCOM) for the Baltic Sea, OSPAR Commission for the North-East Atlantic sea region and the
Regional Marine Pollution Emergency Response Centre (REMPEC) for the Mediterranean Sea.
Furthermore, while the BWMC will reduce the risks of transfer of organisms larger than
10 μm and of bacteria that are harmful to humans, including Vibrio cholerae, Escherichia coli and
Enterococcus spp., the convention does not mention any other aquatic bacteria or viruses that could
cause epizootics in the US$ 160 billion aquaculture industry and threaten food security and human
health (Drillet et al. 2016). Therefore, it has been proposed that risk assessments should be carried
out and eventually flagged to United Nations (UN) interagencies such as UN-Oceans or GESAMP
(Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection) to
circumvent the potential residual risks which may have been omitted in the BWMC (Drillet et al.
Opportunities: Common Treatment Methodologies
While the gaps outlined above are being addressed, there is also an opportunity for the
aquaculture industry, partly due to the efforts of the shipping industry, to advance the technologies
available for water treatment. The BWMC has permitted the development of a range of technologies
which have been tested in independent test facilities in a robust and controlled manner (see above-
mentioned regulations and guidelines). Some of the technologies developed for the shipping
industry are therefore applicable to aquaculture as well. For a ships' ballast water, the technologies
can be either port-based or ship-based, with the latter being easier to implement because it is more
flexible and ensures that systems are able to function during worldwide operations and capable of
treating very dirty/murky waters (Tsolaki and Diamadopoulos 2010). Ballast water treatment
methods can be categorized as physical separation, mechanical or chemical methods (Tsolaki and
Diamadopoulos 2010).
177 Asian Fisheries Science 31S (2018): 168181
Filtration, either by screen or hydro-cyclone filters, is effective against sediment particles and
a wide range of organisms. Hydro-cyclones require less pump pressure than screen filters and allow
separation of sediments and other suspended solids to approximately 20 μm. Particles or organisms
smaller than this require additional treatment methods.
Thus, filtration or separation treatment is generally run in combination with additional
treatment methodologies such as ultraviolet radiation, heat treatment, electromagnetic pulse
applications, oxidizing and non-oxidizing biocides, and deoxygenation (see review by Tsolaki and
Diamandopoulos 2010). These treatment approaches have also been tested and used in aquaculture
(Otte and Rosenthal 1979; Summerfelt 2003). Therefore, lessons learned in the development of
systems for the shipping industry could be readily transferred to the aquaculture sector in order to
maintain the required high levels of biosecurity in farms (FAO 2010).
Ballast water is a vital aspect of maritime safety, as it ensures the stability and safety of the
ship and therefore protects its crew. The USCG and IMO regulations stand as a cornerstone of the
upcoming achievements from the shipping industry. These regulatory regimes, developed to support
the management of the risks inherently associated with the use of ballast water, will help to reduce
the rate and number of exogenous species transferred across ecosystems. Nevertheless, the
understanding of the risks generated by the exchange of ballast water for the aquaculture industry is
generally low. Limitations in the testing of BWMS have been identified and reveal potential impacts
on human health risk management (Cohen and Dobbs 2015). This may also be true for understudied
pathogens in ballast water tanks and their potential impacts on aquaculture, even after the
installation of BWMS in all ships worldwide (see recent work by Ng et al. 2015; Kim et al. 2015;
and Kim et al. 2016).
There is a gap in our knowledge and a residual weakness in the regulatory regimes for ballast
water management which may reveal a continuous risk from shipping to the aquaculture industry
(Drillet et al. 2016). Until this is evaluated, there are dispositions in the BWMC about the measures
which port states are to take in the event of a bloom of potentially harmful organisms occurring in
their waters and where a ship may ballast water from (regulation C-2). In such cases, port states are
required to inform the ships and eventually propose measures to decrease the risk of ballasting water
containing such organisms in ballast water tanks.
The aquaculture stakeholders may benefit from this disposition by ensuring that countries
monitoring the water quality in their port test for pathogens potentially affecting aquaculture, such
as those reported by the World Organisation for Animal Health (OIE, 2017). Impact assessments of
the risk for aquaculture and marine spatial planning may be used as proper tools to ensure improved
biosecurity (Drillet et al. 2014).
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... A risk assessment methodology must be developed to protect the marine environment effectively from HAOP transferred by ballast water. Ships engaged on shortsea voyages between specific ports or locations ("same location") may be granted an exemption from installing BWMS under the BWMC (regulation A-4) if it is assessed that the risk of HAOP transfer is relatively minor [48]. Although this approach is beneficial for liner ship shipowners in specific areas, regional administrations should bear in mind the results of [20] and carefully assess the risks before granting any exceptions. ...
... A risk assessment methodology must be developed to protect the marine environment effectively from HAOP transferred by ballast water. Ships engaged on short-sea voyages between specific ports or locations ("same location") may be granted an exemption from installing BWMS under the BWMC (regulation A-4) if it is assessed that the risk of HAOP transfer is relatively minor [48]. Although this approach is beneficial for liner ship shipowners in specific areas, regional administrations should bear in mind the results of [20] and carefully assess the risks before granting any exceptions. ...
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Ballast water is recognized as a major vector for the transfer of Harmful Aquatic Organisms and Pathogens (HAOP) and a source of sea pollution that negatively affects the environment and human health. Therefore, the International Maritime Organization (IMO) adopted the International Convention for the Control and Management of Ship’s Ballast Water and Sediments (BWM Convention) in 2004. The BWM Convention introduced two standards, Ballast Water Exchange Standard (Regulation D-1) and Ballast Water Performance Standard (Regulation D-2). Ships are required to install Ballast Water Treatment (BWT) equipment in order to comply with Regulation D-2. However, the deadline for the installation of BWT is prolonged until September 2024, and many ships are still complying only with Regulation D-1. In addition, there are specific sea areas where Regulation D-1 cannot be complied with, and hence, HAOP could be easily transferred between ports. Consequently, it is essential to develop a system to protect the marine environment, human health and economy in coastal areas from the introduction of HAOP. This paper analyses ballast water discharged in the Port of Ploče (Croatia) according to ship type, age and flag they are flying. It was found that general cargo ships and bulk carriers discharged most of the ballast (87% of the total quantity) in the Port of Ploče. Moreover, discharged ballast water was analysed according to the origin, and it was found that 70% of discharged ballast originates from the Adriatic Sea. Based on the analysis of the research results and literature review, the ballast water risk assessment (BWRA) method was adopted, however, with certain modifications. The adopted method is modified by an additional risk factor (the deballasting ship’s age), different risk scoring of the deballasting ship type and adding Paris MoU Grey and Black lists flag ships as high-risk ships. As a result, the BWRA method presented in the paper could be used as an early warning system and to facilitate the implementation of adequate measures to prevent pollution by discharged ballast water.
... These, together with the occurrence of other contaminants such as nutrients, pathogens or emerging contaminants may also be transferred to another area. For these reasons, harbors can be considered a point of transfer between aquaculture and shipping [60,61]. Some examples of this transference are the amoebic gill disease (N. ...
... Thus, it should involve a "worst case scenario" that could occur in real water conditions [18,73]. Additionally, the development of efficient ballast water management systems in these scenarios would also benefit some related industries, such as aquaculture, which is also, potentially, affected by possible spread of organisms resulting from an inadequate ballast water management [61,70]. Data Availability Statement: This essay did not report any data. ...
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New observations of non-indigenous species (NIS) in coastal waters, such as the Gulf of Cadiz (Spain) have increased since 1980 and more or less exponentially in the last five years. Ballast water has become the most significant pathway for unintentional introductions of NIS into marine ecosystems. For example, the marine larvae of crustacean decapods that inhabit the water column could be transported in ballast water. Although elevated concentrations of metals are toxic to many marine organisms, some of them have evolved effective detoxification, or avoidance mechanisms making it possible to consider they have a superior ability to withstand exposures to these toxicants. In this text, we try to reinforce the hypothesis that anthropogenic modifications (such as chemical alterations and modified environments) benefit NIS with broad environmental tolerances. Taking these risks into account, a reinforcement of efficient Ballast Water Management Systems to respond to today’s challenging environmental conditions is discussed.
... These activities promote the introduction of aquatic invasive species that can have a huge ecological impact on the environment and destabilize ecosystems. It subsequently causes significant economic and public health impacts due to the proliferation of pathogens and related diseases [3,4]. ...
Controlling pathogens and undesired biofouling in aquaculture or shipping activities is important due to the related potential economic and public health impacts. Accordingly, the treatment of seawater has increased interest in the maritime industry. Advanced Oxidation Processes are promising techniques for the treatment of different aqueous matrices. In this context, sulfate radical-based AOPs appear to be a good alternative for seawater applications. Consequently, the goal of this study is to evaluate the disinfection efficacy of combining the peroxymonosulfate salt ([PMS] = 1 and 5 mg L⁻¹) with an ozonation treatment. Different inactivation processes (O3, PMS, and O3/PMS) have been investigated with Vibrio alginolyticus as a target microorganism. In comparison with single ozonation, kinetic rates have been accelerated by 65% and 123% with the addition of 1 and 5 mg L⁻¹ of PMS, respectively. It results in a synergistic effect for the O3/PMS combination. The transferred ozone dose is also notably reduced for reaching the 4 Log-removal value (O3: 1.53 mg O3 · L⁻¹; O3/PMS: 0.87 mg O3 · L⁻¹ (1 mg PMS·L⁻¹), and 0.59 mg O3 · L⁻¹ (5 mg PMS·L⁻¹)). O3/PMS treatment also presents a greater residual effect and higher acute toxicity of the treated effluent. Results obtained suggest the peroxymonosulfate as a good promoter of disinfection in the presence of O3, not only by increasing the inactivation rate but also in minimizing bacterial regrowth, which implies greater cell damage during treatment processes. Thus, the O3/HSO5- process deserves further research as an alternative to traditional techniques for water treatment.
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Increasing global population has resulted in increased urbanization of coastal areas across the globe. Such an increase generates many challenges for sustainable food production and food security. The development of aquaculture has proven to be an extremely good option to ensure food security (uninterrupted supply and good quality of food) by many countries, especially those with urban areas affected by space limitations such as Singapore. However, the implementation of aquaculture is not without its challenges and impacts to the environment, with Harmful Algal Blooms (HABs) being one of the major concerns in coastal waters. In this review we analyze the development of the aquaculture industry with respect to HABs in Singapore and compare it to similar urban areas such as Hong Kong (SAR China), Salalah (Oman), Cape Town (South Africa), Valencia (Spain), Rotterdam (The Netherlands), Tampa bay (USA), Vancouver (Canada), and Sydney (Australia). Along with HABs, the abovementioned urban areas face different challenges in sustainably increasing their aquaculture production with respect to the economy and geography. This review further assesses the different production and monitoring strategies that have been implemented to counter these challenges while sustainably increasing production. The ongoing COVID-19 pandemic has affected the world with lockdowns and border closures resulting in logistical difficulties in seafood trade which has further accentuated the dependencies on food import. We conclude that the challenges faced by urban areas for sustainable achievement of food security through development of the aquaculture industry can be effectively managed through proper planning, management and collaboration of knowledge/skills on an international level.
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Same Risk Area refers to an area-based approach for the risk assessment of aquatic invasive species that considers the extent of natural dispersal. It is a new addition to the Guidelines on Risk Assessment (G7) under the International Convention for the Control and Management of Ships' Ballast Water and Sediments. The method outlined here to define the extent of a Same Risk Area assesses the connectivity of species of concern within a wider area by combining information from simulated hydrodynamic data and agent-based modelling with the biological traits and habitat preferences of the selected target species.
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Aquaculture is the world’s fastest-growing food-production sector and a crucial contributor to the United Nations’ Sustainable Development Goals. As a group of scientists, ocean-policy experts, aquaculture professionals and technical consultants from international organizations, we argue that, despite recent legislation, fish farms may still be at risk from pathogens in ballast water discharged from ships.
Technical Report
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The International Convention for the Control and Management of Ships' Ballast Water and Sediments (The Ballast Water Management Convention or BWMC) (IMO, 2004) and its associated guidelines aim to reduce the impact of potentially harmful aquatic organisms and pathogens by preventing their spread from one region to another, by establishing standards and procedures for the management and control of ships' ballast water and sediments. Once the BWMC is in force, most ships will be required to treat their ballast water using on-board type approved Ballast Water Management Systems (BWMSs) applying physical and/or chemical means to meet the ballast water discharge criteria (regulation D-2 of the BWMC). In effect, this means that the potential primary invasion from inter-oceanic voyages will be controlled through BWMS. However, ship(s) on short-sea voyage(s) between specified ports or locations across international borders may be granted an exemption from applying ballast water management systems under BWMC regulation A-4, if it is decided that the risk of transfer of invasive species is acceptable. This implies that a risk assessment should be carried out and Guideline (G7) details the recommended process for this. Furthermore, regulation A-4 allows an exemption to be granted for multiple ships and voyages between specified ports and locations. This supports a regional approach to exemption. Although low risk and high risk scenarios are described in evaluating the risk from the transfer of invasive species via ballast water, the risk assessment approaches recommended do not take into account the ability for species to disperse through natural mechanisms. So the risk from shipping is not set into the context of the natural baseline. In effect, the principle of proportionality in risk management has not been considered in G7. Mobile aquatic species and pelagic life stages of marine organisms may disperse naturally across international borders, irrespective of other vectors of transfer such as ballast water. It follows that ships that take short-sea voyages within such an area of natural dispersion are unlikely to greatly alter the consequences from the transfer of potentially harmful and invasive species. Based on rates and patterns of natural dispersion, the area can be viewed as a "Same Risk Area" or SRA. The study presented here proposes a complementary approach for exemption to that recommended in G7, for multiple State, short-sea shipping based on the concept of SRA. It is offers a regional and proportionate approach to exemption that supports consistency, transparency and efficiency in the regulatory process while still providing the same level of environmental protection relevant to the degree of risk.
Conference Paper
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With the efforts made at IMO in recent years with the preparation of the Port State Control (PSC) guidelines, the revision of the G8, the resolution A1088; many countries have recently ratified the Ballast Water Management Convention (BWMC) and therefore an entry into force is considered imminent. For PSC officers, the PSC guidelines offers a 4 steps approach for compliance verification (The "initial inspection", the "more detailed inspection“, the “Indicative sampling”, and finally, the “detailed analysis”). However, under the existing MoUs (i.e. Tokyo, Paris), the amount of information shared between ports may be limited and therefore may not support the decision of PSC officers to pick ships on which more focus should be put when checking for compliance in regards to the BWMC. In our Research Centre at DHI-Singapore, we have initiated the conceptualization of a software to rank ship entering ports with a risk of non-compliance score. The tools which is expected to be developed as a web-based system can be used by every port in the world to rank ships entering local waters from the most likely to the least likely to be in compliance with the BWMC. The “pay as you go” (per ship entry) approach has the advantage that it allows large and small port terminals to enjoy similar tools, supporting the sharing information on type approved ballast water management systems performances in different areas in the world. In fine, this supports the day to day work of PSC officers in accomplishing their duties more efficiently while creating information to better advance the global capacities in Ballast Water Management.
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Studies of marine viromes (viral metagenomes) have revealed that DNA viruses are highly diverse and exhibit biogeographic patterns. However, little is known about the diversity of RNA viruses, which are mostly composed of eukaryotic viruses, and their biogeographic patterns in the oceans. A growth in global commerce and maritime traffic may accelerate spread of diverse and non-cosmopolitan DNA viruses and potentially RNA viruses from one part of the world to another. Here, we demonstrated through metagenomic analyses that failure to comply with mid-ocean ballast water exchange regulation could result in movement of viromes including both DNA viruses and RNA viruses (including potential viral pathogens) unique to geographic and environmental niches. Furthermore, our results showed that virus richness (known and unknown viruses) in ballast water is associated with distance between ballast water exchange location and its nearest shoreline as well as length of water storage time in ballast tanks (voyage duration). However, richness of only known viruses is governed by local environmental conditions and different viral groups have different responses to environmental variation. Overall, these results identified ballast water as a factor contributing to ocean virome transport and potentially increased exposure of the aquatic bioshpere to viral invasion.
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Indicator organisms and antibiotic resistance were used as a proxy to measure microbial water quality of ballast tanks of ships, and surface waters in a tropical harbor. The survival of marine bacteria in ballast tanks appeared to diminish over longer water retention time, with a reduction of cell viability observed after a week based on heterotrophic plate counts. Pyrosequencing of 16S rRNA genes showed distinct differences in microbial composition of ballast and harbor waters. The harbor waters had a higher abundance of operational taxonomic units (OTUs) assigned to Cyanobacteria (Synechococcus spp.) and α-proteobacteria (SAR11 members), while marine hydrocarbon degraders such as γ-proteobacteria (Ocenspirillaes spp., Thiotrchales spp.) and Bacteroidetes (Flavobacteriales spp.) dominated the ballast water samples. Screening of indicator organisms found Escherichia coli (E. coli), Enterococcus and Pseudomonas aeruginosa (P. aeruginosa) in two or more of the ballast and harbor water samples tested. Vibrio spp. and Salmonella spp. were detected exclusively in harbor water samples. Using quantitative PCR (qPCR), we screened for 13 antibiotic resistant gene (ARG) targets and found higher abundances of sul1 (4.13-3.44 x 102 copies/mL), dfrA (0.77-1.80 x10 copies/mL) and cfr (2.00-5.21 copies/mL) genes compared to the other ARG targets selected for this survey. These genes encode for resistance to sulfonamides, trimethoprim and chloramphenicol-florfenicol antibiotics, which are also known to persist in sediments of aquaculture farms and coastal environments. Among the ARGs screened, we found significant correlations (P
The ballast water that stabilizes marine vessels is the greatest source of harmful bacteria and invasive species in aquatic ecosystems. But global action has been slow. We argue that it must take a close look at the ballast-water convention, whose inadequacies highlight fundamental problems with international maritime governance. The lessons learned might steer other global environmental policies, from reductions in greenhouse-gas emissions to mitigating acoustic and light pollution. Going forward, the IMO should develop strategies to ensure that nations enter into its conventions promptly and to coordinate regional actions. It should establish market instruments to provide incentives and reform how maritime data are collected and used.