Ecospeed is a registered brand name of Subsea Indus tries NV Haven 29, Noorderlaan 9, 2030 Antwerp, Belgium Tel: +32 3 213 53 18 Fax: +32 3 213 53 21 info@ecospeed.be - www.ecospeed.be 

## Proposed criteria for safe in-water hull husbandry practices with respect to the risk of transferring

Non-Indigenous Species

with particular attention to Surface Treated Coatings

Subsea Industries Technical Report No. 2009.4 Revis ion 0

Maxim Candries April 20092



### Table of contents

Executive Summary..................................

................................................... .......... 3 Objective ..........................................

................................................... .................. 6 Abbreviations and terminology ......................

................................................... ..... 7

1 Introduction.....................................

................................................... ... 8 1.1 Non-indigenous species (NIS) ................... ............................................. 8 1.2 Shipping vectors...............................

................................................... ... 9 1.3 NIS management strategy: hierarchical approach. ................................. 10 2 Hull fouling management .......................... .......................................... 11 2.1 Fouling settlement .............................

................................................... 11 2.2 Antifouling coatings ........................... .................................................. 1 1 2.3 Fouling removal ................................

................................................... 12 3 Surface treated coatings......................... .............................................. 14 3.1 The incorporation of coating and maintenance te chnology.................... 14 3.2 Effluent analysis and evaluation of non-toxicit y during the in-water cleaning of STCs. .................................. .............................................. 17 4 Assessment of hull fouling extent ................ ........................................ 17 5 Risk factors in the translocation of NIS by hull fouling........................ 20 5.1 Risk assessment with regards to vessel type.... ...................................... 21 5.2 Risk assessment with regards to geographic loca tion and environmental

conditions.........................................

................................................... 22 5.3 Risk assessment with regards to antifouling sys tem .............................. 24

5.4 Niche areas....................................

................................................... .... 24 6 Safe hull husbandry.............................. ............................................... 25 6.1 The need for in-water cleaning ................. ............................................ 25 6.2 Criterion 1: Non-toxic coating ................. ............................................. 27 6.3 Criterion 2: Lightly fouled.................... ................................................ 30

6.4 Criterion 3: Active vessels.................... ................................................ 31 6.5 Total risk factor and procedures............... ............................................. 31 6.6 Suggestions for future research................ ............................................. 32

References .........................................

................................................... ............... 34 Appendix I. Figures of increasing FR...............

................................................... . 383



### Executive Summary

Several regulatory bodies worldwide have put progra ms in place to compile guidelines or regulations aimed at combating the in troduction of non-indigenous species (NIS) associated with shipping. NIS are tra nslocated in a number of ways. Over the last decade, the possible transfer of spec ies by hull fouling has been given due attention and it is now recognized as one of th e most important pathways of NIS

translocation.

Published literature on the subject has mainly focu sed on reporting the spread of NIS in various regions and on identifying the different factors associated with hull fouling that may have caused that spread. Relatively little information is available on management issues, although research efforts are un derway and being published.

The management issues that are generally consideredare in-water cleaning or out-ofwater removal. Since drydock or haul-out facilities offer more possibilities for containment of solid debris and filtering of efflue nts, thus minimizing the risk of toxic paint waste or viable NIS entering port waters, out -of-water removal is generally recommended or even required by authorities.

In terms of preventing the transfer NIS, due attent ion has been given to the efficacy of antifouling technology. The overviews in literature almost invariably discuss coating technology with an emphasis on biocidal and fouling release coatings. Novel technologies are often discussed only in terms of p rospective efficacy.

Virtually no attention has been given to Surface Tr eated Coatings (STCs) and it is the main objective of this report to discuss this conce pt in view of the risk of transferring

NIS.

STCs essentially involve both coating technology an d regular in-water treatment. This treatment consists of a unique conditioning aspect and a cleaning aspect. Whereas cleaning removes any marine fouling in an early sta ge of development, conditioning is carried out with specially designed tools to bri ng the smoothness of the paint surface to an optimum condition and thereby reduce frictional resistance.4

STCs are entirely biocide-free and the analysis of effluent samples has shown that no toxins are released at any stage, either during cur ing, conditioning or the in-water cleaning. In addition, it was found that during in- water cleaning any fouling organisms were crushed to such an extent that the o rganic matter was considered

unviable.

This report reviews the main risk factors involved with hull fouling as a pathway of NIS in order to identify the circumstances in which the overall risk is minimized. The literature survey reveals that the risk of transfer ring NIS mainly depends on the following factors:

1. vessel type; including time spent in port or statio nary, voyage speed,

duration and route

2. geographic location and environmental conditions;

3. antifouling system; quality of its application; age , type, suitability and condition of the antifouling system;

4. presence of niche areas and application of antifoul ing to them;

5. defouling activities, i.e. in-water cleaning or out -of-water removal.

In-water defouling activities have come under envir onmental scrutiny mainly because of concerns of pulse releases of toxins and ineffec tive removal. It is argued that these concerns do not hold for in-water cleaning on STCs. No biocides are released at any stage and because STSs are so durable, there is no concern for preserving the paint system so that maintenance technology can be optimi zed to be as effective as possible. This involves several parameters of the s pecially designed tools such as materials, speed of rotation and operational pressu re.

Several publications have pointed out that in-water cleaning as a remedial measure under controlled circumstances is preferable to an outright ban in order to reduce the

risk on NIS incursions.

It is emphasized, however, that the in-water cleani ng of STCs is not a remedial measure against NIS and therefore on a scale down f rom preventive measures in the hierarchical approach to NIS management. Regular in -water cleaning keeps the5

surface conditions of STCs optimal and lightly foul ed and should be regarded as a truly preventive measure against NIS.

Based on the identified risk factors, criteria for safe hull husbandry with respect to the risk of transferring NIS are proposed. These criter ia are:

1. The ships are coated with an entirely non-toxic pai nt system

2. The hull of the arriving vessel is only lightly fou led, which implies that the hull is only covered by diatom and bacterial sl imes or fine green and brown algae (classified as < 5mm in length)

3. The in-water cleaning is carried out on low-risk ty pe of ships.

Criterion 1 is self-evident (e.g. by the IAFS Certi ficate) and criterion 2 can be checked by underwater inspection using a fouling ra te or index. Criterion 3 depends on the type of vessel, the level of activity (i.e. restricted port residency time) and the service speed. Port authorities should determine lo cally what exactly constitutes a low-risk type of vessel.

The total risk of transferring NIS is minimal if cr iterion 1 is met simultaneously with either criterion 2 or 3. The second criterion is pr eferable because it implies a direct evaluation of the hull fouling extent, but it is pr oposed that criterion 3 is a valid indirect indication that the hull is lightly fouled . In-water cleaning should be allowed when criteria 1 and 3 are met and should be accompa nied by visual inspection to validate criterion 2, with special attention to nic he areas.

In this way, it is argued that regular in-water cle aning coupled with fouling assessment by divers minimizes the risk of a hull b ecoming (heavily) fouled at all.

The report concludes with some recommendations for further research to support the proposed criteria. In particular, it is suggested t hat the viability of defouled material

should be further studied and that a database with the hull fouling extent on STCs is compiled.6



### Objective

This report is submitted to regulatory bodies that are reviewing the relative risks of hull fouling for the introduction of non-indigenous species (NIS) from commercial

vessels.

It is the main objective of this report to present the concept of Surface Treated Coatings and to discuss it in view of the risk of t ransferring NIS. An STC is a preventive measure against NIS that partly relies o n regular in-water cleaning.

The second objective of this report is to review th e risk factors associated with hull fouling and in-water cleaning and to propose criter ia for safe in-water hull husbandry practices with respect to NIS.7



### Abbreviations and terminology

Antifouling system A coating, paint, surface treatm ent, or device that is used on a

ship to control or prevent attachment of unwanted o rganisms, as defined by the IMO. Fouling removal Generic term to denote any defoulin g activities to remove

marine growth from a vessel, either by out-of-water removal (e.g. in drydock or haul-out facilities) or by in-w ater cleaning FR Fouling Rate (cf. Section 4) HHRF Hull Husbandry Reporting Form IAFS Certificate International Anti-fouling System Certificate as stipulated by

the IMO Marine Environment Protection Committee IMO International Maritime Organization Lightly fouled Hull condition whereby the hull is c overed only by diatom and

bacterial slimes or fine green and brown algae (cla ssified as < 5mm in length) Niche areas Submerged parts of a vessel that are at higher risk of being

fouled NIS Non-indigenous species, referring to aquatic sp ecies in this

report SPC Self-Polishing Co-polymer STC Surface Treated Coating that incorporates both coating and inwater maintenance technology TBT Tributyltin VOC Volatile Organic Compounds8



### 1 Introduction

1.1 Non-indigenous species (NIS)

A non-indigenous species (NIS) is a species which has been introduced by human activity to a new geographic area or ecosystem outs ide of its natural distribution range, and which has then established and spread, t hreatening ecosystems, habitats and/or other species, and potentially causing econo mic and/or environmental damage, or harm to human health (GISP, 2008).

NIS in the marine environment are called by a varie ty of names including Invasive Alien Species (IAS), Introduced Marine Pests (IMP), Aquatic Nuisance Species (ANS), Aquatic Invasive Species (AIS) and Harmful A quatic Organisms (GISP, 2008). The term ‘invasive’ is not always used consi stently and may refer to introductions of different extent (Ricciardi and Co hen, 2007). Since this report is concerned with preventing that a non-indigenous spe cies transported by hull fouling reaches invasive status to any extent, the choice i s made for non-indigenous species (NIS).

NIS are now generally recognized as one of the grea test threats to biodiversity globally. In marine and coastal environments, invas ive species have been identified as one of the four greatest threats to the world’s oce ans (Bax et al., 2003; GISP, 2008).

NIS affect biodiversity by displacing native specie s, by altering community structure, food webs and ecological processes, and have now be en documented in the majority (84%) of the world’s 232 marine ecoregions, with pa rticularly high levels of invasion in Northern California, the Hawaiian Islands, the N orth Sea, and the Eastern Mediterranean (Molnar et al., 2008):

- more than 250 introduced species have been reported in San Francisco Bay alone with approximately 350 non-native marine inve rtebrates and algae being considered established in the USA (Ruiz et al., 200 0; GISP, 2008)

- 343 NIS have been found in Hawaii (Godwin et al., 2 004);9 - in the North Sea, Gollasch (2002) reported establis hed populations of 80 introduced species and 61 NIS were reported for Bel gian marine and brackish waters (Kerckhof et al., 2007).

- in the Mediterranean, more than 500 NIS were report ed, the majority introduced via the Suez canal, although there are d istinct differences between the western and eastern Mediterranean, with far few er introductions in the west (Galil, 2008).

NIS also impact on commercial fisheries, including mariculture with serious economic implications. In addition, fouling of phys ical structures by introduced species has major impacts on other industries by, f or example, decreasing the speed of vessels and clogging water intake pipes (GISP, 2008 ).



### 1.2 Shipping vectors

The means and routes by which species are introduce d into new environments are called pathways or vectors. A number of studies ha ve looked at the relative importance of shipping in relation to other pathway s. Such studies are complicated by the facts that the provided information is often in complete and that numerous species have probably been introduced by several vectors at different times and in different geographic areas (GISP, 2008). In any case, it is g enerally agreed that the rate, and thus the risk, of species invasions has increased s ignificantly during recent decades. One of the primary factors leading to this increase has been the vast expansion of global trade during the past years, which in turn h as lead to significantly more ballast water, fouled hulls, and associated organisms movin g around the world (Minchin and Gollasch, 2003).

A recent analysis by Molnar et al. (2008) drawing o n information from over 350 databases and other sources, showed that for the 32 9 marine NIS considered, shipping was the most common pathway (69%), with others bein g aquaculture (41%), canals (17%), the aquarium trade (6%), and the live seafoo d trade (2%) whereby, on average, 2 pathways per species were identified. Of the 205 species introduced via shipping –

and for which sufficient information was available – 39% were introduced by hullfouling, 31% via ballast water, and the remainder b y both.10

A study on ship-related vectors of introduction int o the North Sea between 1992 and 1996 found that samples of hull-fouling, taken from 186 commercial vessels visiting German ports, had more than twice the number of NIS as those from ballast water – 74% of the species identified. The study concluded that, despite inevitable differences in sampling methodology, hull fouling was an import ant – if not the most important – vector for introductions (Gollasch, 2002).



### 1.3 NIS management strategy: hierarchical approach

The first step in a biological invasion is the intr oduction of the species concerned into the new environment. Once there, the species must b e able to survive in the ambient conditions (temperature, salinity, etc.), and the s urvivors must persist and reproduce successfully until they establish a self-sustaining founder population. Once established, the species begins to multiply and spr ead, sometimes after a substantial time lag – maybe a few years, or even decades. The period of spreading – sometimes known as the explosion phase – is when the species/ population becomes invasive (GISP, 2008).

Management measures may be applied at various point s in the process of invasion, starting from prevention of introductions, to early detection of introduced species or founder populations and rapid response thereto – in the form of eradication or containment - and long-term control of invasive pop ulations. The further along in the process of invasion that the measure is applied the more costly and less effective it generally is. In other words, although prevention m easures may be costly, an analysis of the long-term costs and benefits (environmental, economic and social) will invariably show that they are less than the losses and costs which are incurred if the NIS are allowed to establish, acquire invasive stat us, and then require ongoing

control.

The starting point for the management of NIS – as f or most environmental problems - is that prevention is better than cure. In other wo rds, prevention is the most costeffective and environmentally desirable option, and should be given priority in any management strategy. This is commonly known as the hierarchical approach to11

management of biological invasions. Prevention is e specially important for marine environments given the difficulties of detecting in troductions in marine habitats, of eradicating species that have become established, a nd of functional control and mitigation programs (GISP, 2008).



### 2 Hull fouling management

2.1 Fouling settlement

Preventing the introduction of NIS and spread via f ouling requires adherence to effective antifouling technology aimed at one of th e following three approaches: i) preventing the settlement of fouling organisms by r epelling or killing them; ii) preventing growth of settled organisms by killing t hem, inhibiting their growth or reducing their adhesion ability, iii) removing and disposing of biofouling organisms that have established.

Antifouling coatings are commonly applied for the f irst two approaches, whereas the third approach.is concerned with fouling removal, e ither by underwater cleaning or by out-of-water removal (e.g. in drydock.or haul-out f acilities).



### 2.2 Antifouling coatings

Antifouling coatings broadly function in one of two ways: i) The coating contains biocides or non-toxic acti ve agents which gradually leach from the coating, thereby deterring the settl ement of marine organisms; ii) The coating aims to prevent attachment of marin e organisms – mainly fouling-release or metallic coatings.

The most widely applied type of biocidal antifoulin gs are self-polishing copolymers (SPCs), which allow a gradual release of the biocid e from the polymer. Other types of biocidal coatings leach their toxins faster and do not last as long as SPCs.12

The biocide tributyltin (TBT) dominated the market because of its wide spectrum efficacy and but its use has been banned completely as of September 17, 2008. As it

became clear that the use of TBT would be banned so oner or later, and particularly during the phase-out period, it has often been ment ioned in the literature that the risk posed by hull fouling as a transport mechanism for NIS may increase as new coatings are developed and vessels shift to different antifo uling coatings with potentially lower efficacies (Drake and Lodge, 2007).

Most SPCs now use copper compounds as biocides, tho ugh they are generally less effective and their longevity is shorter than TBT. In addition, bans and restrictions on copper-based paints are being considered in a numbe r of places so there has been increasing emphasis on the development of environme ntally acceptable, biocide-free, alternatives (Lewis, 2002b).

While several biocide-free coatings are in developm ent to prevent the settlement of organisms, the majority of biocide-free coatings th at are presently on the market are formulated to prevent firm attachment and developme nt of fouling organisms. These coatings are known as foul(ing) release coatings (C hambers et al., 2006). They are more costly to apply than biocidal antifoulings and are currently only practically effective for active, swift vessels (Falkner et al. , 2009).



### 2.3 Fouling removal

The frequency with which most vessels remove foulin g is usually based on the maintenance rules of the classification society (i. e. organization that establishes and applies technical standards for ship design, constr uction and survey). Vessel-specific programs may include a five-year cycle of annual in -water surveys and special out-ofwater (i.e. drydock or slipway) surveys. Most vesse l owners commonly take advantage of required drydockings to remove fouling organisms and apply new antifouling coatings.

Because fouling continues to accumulate between req uired drydockings, vessel owners also conduct interim in-water cleanings of t he vessel hull. In-water cleaning techniques generally vary depending on the size of the vessel as well as the13

composition of the hull and the type of antifouling paint applied thereon. Small vessels (i.e., less than 25m) are typically cleaned by divers using hand-held scrapers, while commercial vessels generally require diver-op erated devices with rotating

brushes.

With the shift to TBT-free antifoulings, there has been a surge in antifoulings losing their efficacy more rapidly than the previously com mon 5-year inter-drydocking period (Drake and Lodge, 2007). As a consequence i n-water cleaning practices have increased in recent years to extend the time betwee n an antifouling losing effectiveness and drydocking. For commercial vesse ls, the diver operated machines with rotating brushes can clean the hull while the ship is loading or unloading in port. Such practices, however, have become increasingly r estricted because of concerns about the pulse release of antifouling biocides dur ing the scrubbing of the paint (Conway and Locke, 1994; Valkirs et al., 1994).

Out-of-water fouling removal during drydock allow f or the containment of toxic materials, including fouling organisms that are rem oved from the vessel hull. Even though out-of-water removal is not 100% effective a t containing debris and depends on environmental-, facility- and biotic-related var iables, the debris produced during water-blasting carried out at drydock or haul-out f acilities generally contains fewer viable organisms than in-water cleaning (Woods et a l., 2007). Especially mobile organisms such as byssal mussels and other molluscs , dislodged during cleaning can be transported by currents to nearby substrates suc h as pilings, rocks, or rubble and sand patches where they can settle and re-attach. M oreover, it has been reported that the crushing of invertebrate species can release eg gs and sperm, while fragments of some macroalgae - such as Caulerpa - bryozoans, asc ideans, sponges and worms such as Sabella can regenerate (Lewis, 2002a; Hopkins an d Forrest, 2008). In-water cleaning, therefore, has increasingly come under sc rutiny not only due to concerns about toxins and water quality, but also because of NIS introductions (Falkner et al., 2009).

To address this issue, experimental in-water cleani ng technology is being researched and developed to in order to retain all defouled ma terial and released substances. At present, these systems are not yet fully effective. Hopkins and Forrest (2008) tested14

two diver-operated rotating brush systems which wer e coupled with a purpose-built suction and collection capability and found that ev en where brushes were combined with a suction system to collect the material, up t o 12% was still lost.

As an alternative to remove fouling by in-water cle aning, in-water encapsulation techniques have recently been developed. Although t hese techniques appear promising, the development of anoxic conditions may be too slow to cause mortality where the time frames of visiting vessels are short and they are therefore not yet a viable option at present for commercial vessels (Ho pkins and Forrest, 2008).



### 3 Surface treated coatings

3.1 The incorporation of coating and maintenance te chnology

As mentioned in Section 2.1, antifouling technologi es may be distinguished based on the sequence of settlement. A consequence of this c lassification, however, is that coating technology is commonly regarded as the only preventive measure with respect to NIS, whereas cleaning technology is regarded as a remedial measure (i.e. on a scale down in the hierarchical approach to management of NIS, cf. Section 1.3).

Figure 1 gives an overview of antifouling systems t hat rely on coating technology and those that do not. An antifouling system is hereby defined by the International Convention on the Control of Harmful Antifouling Sy stems on Ships, 2001 (AFS Convention) as “a coating, paint, surface treatment , or device that is used on a ship to control or prevent attachment of unwanted organisms ”.

This Section deals with Surface Treated Coatings (S TCs), which is a concept that is often overlooked and that was originally not includ ed in Figure 1. The edit in red on Figure 1 shows that STCs involve both coating and n on-coating technology.15 Figure 1. Technologies and strategies to combat bi ofouling on submerged surfaces (Willemsen, 2005) (Edited).

Surface treated coatings are by definition subjecte d to regular in-water treatment. The treatment consists of a conditioning aspect that im proves the surface characteristics of the coating and a cleaning aspect that removes any marine fouling in an early stage of development (Van Rompay, 2008).16

One STC that is commercially available under the br and name Ecospeed, is formulated as a vinyl ester with a high concentrati on of embedded glass platelets. This coating has a low amount of volatile organic compou nds (VOC) and is typically applied in two coats of 500 μ m, which is considerably higher than the total dry film thickness of traditional antifouling schemes. The h igh film thickness and the presence of glass flakes which act as an impermeable barrier contribute to the anti-corrosive properties and the high durability explain why the coating is so well suited for regular

in-water treatment.

The conditioning aspect is unique to STCs because t his in-water treatment results in a smooth but wavy surface to which fouling organisms have difficulty re-attaching. In effect, for the commercial STC example given above, the conditioning results in a surface layer of aligned glass platelets that are s uspended in a leveled matrix of vinyl

ester. It is assumed that the number of crevices ar ound the impermeable glass flakes is drastically reduced which would explain why good an tifouling properties are obtained for a coating which was originally developed as an anti-corrosive barrier coating. Ongoing research is evaluating this assumption by stu dying the roughness characteristics over short cut-off lengths (Van Rompay, 2008).

Figure 2. In-water treatment by rotating brush tech nology of a hull coated with STC.17

By means of specially developed tools, the conditio ning and cleaning operations of an STC can be carried out simultaneously, as shown in Figure 2. This significantly reduces the required amount of time and consequentl y saves on costs.



### 3.2 Effluent analysis and evaluation of non-toxicit y during the inwater cleaning of STCs.

Wijga et al. (2008) studied the effluents released at various stages in the lifecycle of a commercially available STC. By chemical analysis th ey found that in the curing phase only aromatic solvents were leached (xylene, styren e). During the conditioning 168 hours after exposure in artificial seawater, non-to xic polymer was also released. The absence of biocidal substances was validated by tox icity and oestrogenic tests on a number of organisms.

During the in-water cleaning of a test plate which had been exposed in seawater for 1 year and which was moderately fouled, the compositi on of the released substances was significantly different: aromatic solvents and non-toxic polymer were only present in modest quantities as the released substa nces consisted mainly of crushed organic matter. A taxonomic analysis of the fouling organisms present prior to inwater cleaning was not carried out.

The reported concentrations of released matter were analyzed in a volume of water that was restricted by the dimensions of the test b asin. In practice, the concentrations of released effluent, either during cleaning or con ditioning, will be diluted by naturally occurring current and flow effects (Wijga et al., 2008).



### 4 Assessment of hull fouling extent

No matter how effective the antifouling system, fou ling of submerged surfaces will occur sooner or later. The process of biological fo uling is often grouped in the literature into key growth stages which include an initial accumulation of adsorbed organics, the settlement and growth of pioneering b acteria creating a biofilm matrix within a matter of hours upon immersion and the sub sequent succession of micro and macrofoulers (Chambers et al., 2006). Settlement of the latter almost invariably takes18

place in port regions when ship speeds are low or w hen ships are anchored or berthed since few species attach to substrates at speeds of > 2m/s (Minchin and Gollasch, 2003).

Compared to the ballast water vector, there is very little recent data directly from commercial ships on which assessments can be made r egarding the movements of species at various scales and the factors that infl uence biofouling accumulation, survival and species incursions (Davidson et al., 2 006).

Hull sampling of commercial vessels is traditionall y achieved by divers when the ship is in water or during drydocking events when the sh ip is more readily accessible. A major constraint of drydock surveys is that vessels tend to be skewed toward the most

fouled vessels that have reached the end of their i nter-drydocking period. In addition, accessibility to all locations on the hull is not g uaranteed, usually rendering much of the hull’s area (beyond the reach of a step ladder) inaccessible. The unconstrained field-of-view of the vessel is beneficial, however, as is the controlled environment in which the survey takes place, the collection of spe cimens for species level identification, and the low cost of data collection

.

Underwater inspection allows for a more representat ive subset of vessels to be sampled with access to all underwater locations and species level data collection but may be constrained by visibility (Davidson et al., 2006).

Methodologies have been proposed to assess the leve l of fouling on a hull based on the change in fouling communities over time.

Floerl et al. (2005) developed an index to assess l evels of fouling on small craft. Table 1 shows that the index goes from 0 – 5, with, for e xample, 0 indicating no biofilm or macro-fouling; 2 indicating light fouling - hull covered in biofilm, with 1 – 5% of the surface with small patches of macro-fouling; an d 5 indicating very heavy fouling with 41-100% coverage of the hull surface by divers e assemblages of fouling species.19 Table 1. Fouling index used to quantify hull foulin g on private yachts arriving in New Zealand (Floerl et al., 2005a).

Floerl et al. (2005) carried out a visual inspectio n of 189 yachts in situ using a remoteoperated video camera

. 55% of the vessels surveyed were allocated a fouli ng index of 0 or 1, with an average macrofouling coverage of 0. 1 ± 0.1%. 12% of vessels were allocated an index of 2, with average macrofouling coverage of 4.35 ± 2.39%. None of the remaining third of vessels surveyed with an allocated index of 3-5 were devoid of macrofouling.

Because of the need for longer inter-drydocking int ervals, hull husbandry practices have always been common on navy vessels, even in th e era of antifoulings containing tributyltin (Preiser et al., 1975). The US Naval Sh ips’ Technical Manual contains several criteria for evaluating fouling severity an d coating condition. The fouling rating scale given in Table 2 describes the ten mos t frequently encountered fouling patterns in order of increasing severity. The types of fouling are separated into soft, hard, and composite categories and the fouling rati ng is then further refined by the percentage of covered area. For illustrative purpos es, 22 figures directly taken from the Manual, are included in Appendix I.

It seems logical to use either of these methods or a similar method in the hull fouling assessment of commercial vessels but at present thi s is rarely done during underwater inspections.20 Table 2. US Navy Fouling Ratings (FR) in order of i ncreasing severity (Naval Ships' Technical Manual, 2006)



### 5 Risk factors in the translocation of NIS by hull fouling

The threat of possible NIS transferred by hull foul ing depends on a variety of factors which influence the likelihood of any particular ve ssel carrying potentially harmful species. The most important factors are:

1. vessel type; including time spent in port or statio nary, voyage speed,

duration and route

2. antifouling system; quality of its application; age , type, suitability and condition of the anti-fouling system;

3. geographic location and environmental conditions;

4. presence of niche areas and application of antifoul ing to them;

5. defouling activities, either by out-of-water remova l or by in-water cleaning.

The concerns about defouling activities have been d iscussed in Section 2.3, while the

other factors are discussed below.21



### 5.1 Risk assessment with regards to vessel type

It has long been known that ships on active duty te nd to be less fouled than those which spend much of their time stationary. This is mainly because fouling organisms will only attach to slowly moving surfaces (cf. Sec tion 4) but also because vessels with short port residency times generally invest in better antifouling measures.

Biofouling on a ship’s hull will increase the hydro dynamic drag and lower the maneuverability of the vessel, leading to increased fuel consumption (Chambers et al., 2006). Depending on the type of vessel, fuel may ma ke up about 50% of the operational costs of a ship, and it has been estima ted that fouling increases the annual fuel consumption of the commercial shipping fleet b y 40%, or 120 million tonnes of fuel at a cost of about $ 7.5 billion in 2000 per y ear (GISP, 2008).

For commercial vessels, the increased drag and asso ciated fuel consumption as a result of biofouling alone make it economically ine vitable for shipping companies to invest in antifouling technology, i.e. coatings and /or cleaning measures. Other benefits include the improved maneuverability, whic h can be impaired by propeller fouling and better control of microbially induced c orrosion (Chambers et al., 2006).

Trading vessels include chemical tankers, container ships, crude oil, gas and dry bulk carriers, general cargo ships, livestock carriers, product tankers, vehicle carriers, various roll-on roll-off ferries and cargo ships (r o-ro vessels).

It is clear that low activity vessels present a hig h risk. These include barges, drilling platforms and dredgers. With the decline in fish ca tches in many parts of the world, many commercial fishing vessels are underutilized a nd poorly maintained with vessels being laid up and/or sold off for fisheries or other purposes in other areas. They therefore also represent a considerable risk i n terms of hull fouling (Godwin, 2003; Minchin and Gollasch, 2003; GISP, 2008).

Small craft have long been known to play an importa nt role in the spread of NIS and their role in the spread via hull fouling has been investigated in depth. The emerging22

picture suggests that these vessels in fact pose a significant threat for various reasons (Floerl and Inglis, 2003; Mineur et al., 2008) :

- many are stationary for long periods of time,

- they are often poorly maintained,

- the probabilities of yacht-mediated dispersal are m ultiplied by the relatively high numbers of recreational yachts sailing along s hores

- most are moored in marinas or in sheltered bays or estuaries which provide ideal conditions for the establishment and spread o f fouling organisms.

Based on a survey of the voyage characteristics of 400 vessels (through the collection of hull husbandry reporting forms), Falkner et al. (2009) suggest a gradient of risk associated with different vessel types, with auto, container, and passenger vessels posing the lowest amount of risk and barges, bulk, and tank vessels posing the greatest amount of risk. The lower risk vessel clas ses all share short average port residency times, elevated traveling speeds and fres hwater port calls (Falkner et al., 2009).



### 5.2 Risk assessment with regards to geographic loca tion and

environmental conditions

The ability of NIS to invade a particular port will vary according to the degree of biophysical similarity between its native range and that available in or close to the port of introduction. Critical parameters include e xtreme maximum and minimum temperatures, salinities, dissolved oxygen levels a nd sediment stability (Hutchings et al., 2002). It is long known (e.g. by the pioneerin g work of Visscher) that fouling organisms are capable of surviving on vessels remai ning at similar latitudes because of the relatively consistent ambient water temperat ures (and sometimes salinity levels) at similar latitudes, and short voyages have little influence on the ability of biofouling organisms to feed and grow rapidly (Woods Hole Ocea nographic Institution, 1952).

Other factors include the composition, biodiversity , health and stress status of the organisms that are present in the port of arrival. Healthy communities will be able to offer stronger resistance to invasive alien species and diverse communities will offer fewer opportunities of introduction.23



### 5.2.1 Example: Northern Australia vs. Hawaii

Whether or not a NIS may become invasive depends on a number of factors and a good example of this is a comparison of the well-do cumented cases of Northern

Australia versus Hawaii.

Hutchings et al. (2002) report a number of surveys looking for introduced species in tropical ports across northern Australia. The surve ys supported the conclusions from a 1997 risk assessment examining introductions to 12 tropical ports in Queensland (Northern Australia) which concluded that far fewer marine species appeared to have been introduced, even at major bulk export ports wh ere the number of ship visits and volume of discharged ballast water are more than at most of Australia’s cooler water ports. The 1997 report also concluded that, apart f rom pathogens and parasites of warm-water species, the potential for marine pest i nvasions in Queensland tropical ports appeared to be low, and not only because the majority of arriving vessels originated from temperate ports in North Asia, incr easing the likelihood that NIS will not survive the changes in temperature, salinity et c. (Hutchings et al., 2002).

In contrast, surveys of harbors in Hawaii have foun d over 110 introduced species (including 23 cryptogenic species, i.e. opportunist ic cosmopolitan species). Hutchings et al. (2002) suggest that the biogeographically is olated and less diverse marine communities of Hawaiian ports have been more suscep tible to introductions than those of tropical Australia for several reasons, in cluding the proximity of Australia to the central Indo-Pacific triangle of megadiversity ( Indonesia-Philippines-Papua New Guinea) and consequent high biodiversity and low en demicity, hence offering fewer niches for non-indigenous species to become establi shed.

These considerations should be combined with the ri sk factor described in the previous Section. With regards to arriving vessel t ypes, the isolated central Pacific position of Hawaii has a long history of receiving a relatively large share of naval shipping, which pose a markedly greater risk of bei ng heavily fouled than highactivity bulkers that predominantly arrive in north ern Australian ports (Hutchings et al., 2002).24

Baseline surveys of several of these ports have bee n carried out to further monitor the risk of NIS incursions (Hoedt et al., 2001; Neil et al., 2008).



### 5.3 Risk assessment with regards to antifouling sys tem

Several studies have reported that paint age is the most important factor governing the effectiveness of antifouling coatings on both recre ational (Floerl and Inglis, 2005; Floerl et al., 2005b) and commercial vessels (Coutt s and Taylor, 2004; Otani et al., 2007). This is simply because the majority of appli ed coatings are still biocidal, and

with time there is an increased likelihood that the coatings are depleted of biocides.

Mechanical integrity and quality of application is another important factor. Piola and Johnston (2008) studied fouling taxa recruitment on experimental scrapes of paint surfaces and concluded that slight disruptions to n ewly antifouled surfaces may be all that is necessary for the establishment of fouling organisms and the translocation of a wide range of invasive taxa (Piola and Johnston, 20 08).

It should be noted that long stationary periods red uce the effectiveness of both biocidal antifoulings and fouling release coatings.



### 5.4 Niche areas

Fouling organisms tend to concentrate in sheltered areas of the hull, such as sea chest intakes, the rudderpost and other crevices which ar e protected from turbulent flow (Coutts et al., 2003). Other areas which require sp ecific attention are drydock support strips that are often left uncoated. These have bec ome known as ‘niche areas’ and should be inspected with special care.25



### 6 Safe hull husbandry

6.1 The need for in-water cleaning

In-water cleaning should remain a viable option for hull fouling management. From an economic point of view, there is great demand fr om ship operators to sail with optimum hull condition. From an environmental point of view, avoiding the added drag of a fouled hull will save on fuel consumption and reduce greenhouse gas emissions. Drydocking or out-of-water removal is an expensive option that is not always available or feasible. With potentially less effective biocidal antifoulings after the TBT ban, in-water cleaning is therefore often t he only option to extend the interdrydocking period.

Leaving a fouled hull totally unmanaged poses a gre at risk of introducing NIS. Once heavily fouled vessels arrive in a new port with al ready mature species, cues within enclosed harbor basins or estuaries, such as change s in temperature or salinity, can stimulate these adults to spawn within a few hours of arrival, with nearby wharf piles, jetties, breakwaters and other hard surfaces offeri ng convenient settlement areas (Minchin and Gollasch, 2003; GISP, 2008). Fouling o rganisms may also be dislodged during mooring operations (Takata et al., 2006). Mo reover, mobile organisms, such as crabs or seastars, which are typically nestled amon gst encrusting species on heavily fouled vessels, may find ways to escape from the hu ll and settle within the vicinity of port waters (Lewis, 2002a).

It is clear that heavily fouled vessels should be t reated with care and only after this has been given due attention by the authorities, e. g. by deciding which is the most viable management strategy and by issuing permits o n a case-by-case basis.

A heavily fouled hull implies that the antifouling system has failed as a preventive measure in the transfer of NIS. Too often, in-water cleaning is only considered at this stage, i.e. when heavy fouling is either clearly vi sible or evident through markedly increased ship fuel consumption. In-water cleaning is then an option as a remedial measure against NIS, which has come under increased environmental scrutiny.26

Several researchers have nevertheless pointed out t hat in-water cleaning as a remedial measure under controlled circumstances is preferabl e to an outright ban in order to reduce the risk on NIS incursions (Lewis, 2002b; Ho pkins and Forrest, 2008). For example, it may be advisable that a vessel that has been stationary for a long time and has acquired substantial fouling is cleaned in-wate r before it leaves port and sails elsewhere. Figure 3 illustrates the risks of in-wat er cleaning as a measure against NIS versus the risks of no management measure whatsoeve r.

Figure 3. Conceptual diagram of the risks posed by a fouled vessel if left unmanaged compared with the risks of in-water cleaning (Edited from Ho pkins and Forrest, 2008).

It should not be forgotten, however, that in-water cleaning may also be a preventive measure. or a precautionary approach to managing hu ll-fouling NIS (Woods et al., 2007). This is indicated in red in Figure 3, which is edited from Hopkins and Forrest27

(2008). Hull cleaning as a preventive measure occur s when theoretically no fouling is present and in practice when the hull is ‘lightly f ouled’ (which is further discussed in Section 6.3 below). This is the design scenario for STCs where regular in-water cleaning to keep fouling to a minimum is essential to the whole concept. STCs combine maintenance and coating technology to provi de an effective preventive measure against NIS. As the fouling extent magnifie s, however, the baseline risk with potential release of planktonic propagules or dispe rsed fragments increases and inwater cleaning becomes a remedial measure against N IS.

The main premise of this report is to argue that th e in-water cleaning of hulls of ships exceeding 25m in length can be an acceptable preven tive measure and will not exacerbate the risk of spreading NIS if a number of criteria are satisfied. These

criteria are:

1. the hull is coated with an entirely non-toxic paint system

2. cleaning is only carried out when the hull is light ly fouled

3. cleaning is only carried out on ships which have a sufficiently high level of activity and which have not been stationary for lon g periods



### 6.2 Criterion 1: Non-toxic coating

In-water cleaning is only truly acceptable when the release of toxic matter is entirely avoided and when it leaves the paint system undamag ed. As mentioned in Section 2.3, the main concern of cleaning hull surfaces is that it may result in a pulse release of biocides around the vessel and gradual buildup of t oxicity levels within port waters (Valkirs et al., 1994). Another aspect of in-water cleaning is that it is likely to remove at least part of the existing anti-fouling, reducin g he scheduled lifetime of the paint system. Since no new paint is applied, it therefore increases the chance of the surface being recolonized. Boats that had been cleaned in A ustralia, for example, were found to have up to six times more recruitment than those that had been sterilized or left uncleaned (Floerl et al., 2005b; Hopkins and Forres t, 2008).

The only types of biocide-free antifoulings which a re currently in use on a commercial basis are fouling release and surface tr eated coatings. Fouling release coatings, however, pose the disadvantage that they are mechanically soft and28

therefore easily damaged (Meyer et al., 1995; Eiss, 1999; Holm et al., 2003). In addition, Nendza (2007) states that the silicone oi ls which are present in a number of fouling release coatings formulated around chains o f polydimethylsiloxane may leach out from the coatings. These oils are highly persis tent and have low solubility in water. Consequently, they may clog surface sediment s and cause anoxic conditions (Nendza, 2007).

It is proposed that cleaning on foul release coatin gs is accompanied by visual inspection using a paint deterioration rating (cf. Section 4) to ensure that the coating is in acceptable condition.

STCs, however, are specifically formulated to be su bjected to regular in-water cleaning by specially designed tools. Because of th eir durability, higher forces can therefore be applied by the tools than the rotating brushes traditionally used for other antifoulings and preserving the life span of an STC is not an issue. In-house research and development has determined the best combination of design parameters such as for surface optimization (i.e. conditioning) and or ganism removal (i.e. in-water cleaning). With respect to removal, various configu rations and materials can be selected, depending on the inter- and intra-specifi c variation in adhesion strength among organisms. In addition, smaller and more flex ible tools have specially been designed to address niche areas. To illustrate this , Figure 4 (Hopkins and Forrest, 2008) shows that in general, removal by brushes is not 100% effective and becomes increasingly ineffective as the fouling extent prio r to treatment is greater. In contrast, Figure 5 shows the hull of a cruise vessel coated w ith STC which had spent nine months stationary in tropical waters. The upper lef t part of the picture shows the fouling extent whereas the lower right part of the picture shows the effective removal where the in-water cleaning tools have passed.29 Figure 4. Photographs of settlement plates (350 by 350 mm) before and after treatment by rotating brushes after (a) 3 months and (b) 12 mont hs of fouling (Hopkins and Forrest, 2008).

Figure 5. Photograph taken underwater of a hull co ated with STC that is partially covered by fouling after spending 9 months stationary in tropi cal waters (upper left) and that has partially undergone in-water cleaning (lower right).30

In addition, as mentioned in Section 3.2, effluent analysis has shown that any substances released during in-water cleaning of STC s are non-toxic and that all

defouled material is crushed to the extent that it is not considered viable (Geens, 2008; Wijga et al., 2008).

Woods et al (2007) compared the viability of organi sms in solid debris and found fewer viable organisms after water blasting in dryd ock and haul-out facilities than after in-water cleaning by manual scraping, with le ss damage done to soft-bodied taxa than to brittle hard-bodied taxa by either cleaning method. It may be expected, however, that the pressure put on organisms by rota ting brushes used for the in-water cleaning of commercial vessels strongly reduces the overall viability compared to manual scraping. Preiser et al (1975) compared seve ral methods of in-water cleaning

and concluded that brush machines were the most eff ective removal method. The advantage of STCs over other coatings in this respe ct is that significantly more pressure can be transmitted by the specially design ed in-water cleaning tools to effectively remove and crush fouling organisms with out damaging the surface.



### 6.3 Criterion 2: Lightly fouled

It is proposed to automatically allow the in-water cleaning of ships arriving in port areas when the hull is ‘lightly fouled’ only. This includes the presence of diatom and bacterial slimes which are not distinguished from b are metal and anti-fouling paint with any certainty and are therefore generally not included as separate taxa in surveys of fouling extent (Coutts and Taylor, 2004). It is generally agreed that the adhesion of slime films cannot be prevented by any type of anti fouling, including biocidal and foul release coatings (Anderson et al., 2003; Holla nd et al., 2004). A ‘lightly fouled’ hull may also be covered by fine green and brown al gae (classified as < 5mm in length). In terms of Floerl et al.’s fouling index, this proposition would effectively imply a fouling index of less than three.

It may be argued to also allow moderate levels of f ilamentous algae (i.e. longer than 5 mm in length) since these are generally cryptogenic and pose no risk as NIS. This would imply to allow a fouling index of 3 or a Navy fouling rate of 30 with limited cover (cf. Section 4). Port authorities should deci de whether this is locally acceptable31

since there is some discussion as to which species are regarded as cryptogenic (Gollasch and Nehring, 2006; Kerckhof et al., 2007; Minchin, 2007).

The US Navy combines the Fouling Rating with a Pain t Deterioration Rating in order to determine when hull husbandry should be performe d and to what extent. The decision to initiate an in-water cleaning operation is based on the results of precleaning hull inspections performed on regularly sc heduled intervals (Naval Ships' Technical Manual, 2006). The difference here is tha t it is proposed to allow in-water cleaning below a certain fouling rate, whereas the Navy performs cleaning above a certain fouling rate.



### 6.4 Criterion 3: Active vessels

There is general agreement that high activity vesse ls with short stays in port represent a low risk with respect to transferring NIS (cf. Se ction 5.1). Based on the type of vessel, the service speed and the documented activi ty level (i.e. latest port entries), it is proposed that criterion 3 could be an alternativ e to criterion 2.

Port authorities should determine locally what exac tly constitutes a low-risk type of vessel. Ports in tropical waters, for example, may require higher service speeds, shorter port residency times or, in the case of STC s, shorter intervals between inwater cleanings.



### 6.5 Total risk factor and procedures

The total risk of transferring NIS is minimal if cr iterion 1 is met simultaneously with either criterion 2 or 3. The second criterion is pr eferable because it implies a direct evaluation of the hull fouling extent, but it is pr oposed that criterion 3 is a valid indirect indication that the hull is lightly fouled

.

The advantage of initially validating criteria 1 an d 3 is that they can readily be demonstrated by providing the appropriate documents (e.g. IAFS Certificate in combination with latest port entries) so that in-wa ter cleaning can be allowed for a ship arriving in a port without the lengthy procedu re of applying for a permit, now32

often given on a case-by-case basis. During in-wate r cleaning, visual documentation

should then be collected to validate criterion 2. T his documentation, preferably in the form of a fouling rating and paint deterioration ra ting accompanied by archival video material and diver report forms that pay special at tention to niche areas, should be kept onboard. The visual documentation and monitori ng will also provide evidence that regular in-water treatment is a justified prev entive measure. This will contribute to the evaluation of hull fouling as a NIS vector a nd can serve as an appropriate monitoring program to inform adopted management app roaches in general (Neil et al., 2008).

In this way, it may be argued that regular in-wate r treatment coupled with fouling assessment by divers minimizes the risk of a hull b ecoming (heavily) fouled at all. Over the last couple of years a lot of new paint fo rmulations were launched in order to find the best response to the TBT ban. Not all of t hese formulations have been as successful as hoped and it may be argued that the l ast decade has seen more heavily fouled vessels than the decade before (Drake and Lo dge, 2007). Allowing regular inwater cleaning when the criteria proposed above are satisfied would avoid this.

The in-water cleaning and inspection frequency will depend on the type of vessel (i.e. service speed and port residence time) and the voya ge route. As a first indication, a frequency of twice a year may be assumed for vessel s plying only temperate waters and every three months for vessels plying tropical waters.



### 6.6 Suggestions for future research



### 6.6.1 Viability of defouled material

This literature survey indicates that the viability of organisms removed by rotating brush technology or by the in-water cleaning tools used with STCs have not been studied by quantitative assessments for different t axa. This could be researched by following a similar methodology to Woods et al. (20 07) whereby fouling organisms removed from hulls are collected using catch bag s made from fine nylon mesh (0.2 mm). The fouling organisms are consequently placed in sorting trays filled33

with clean filtered (60 μm) seawater, and th e viability of organisms can be assessed using the procedures described by Woods et a. (2007).



### 6.6.2 Hull fouling assessment

The extent of hull fouling on non-toxic coatings sh ould be further evaluated in order to find further support that criterion 3 is a valid alternative to criterion 2. This may be done by taking a number of photographs (20 by 20 cm ) during underwater inspections at selected areas around the hull (including rudder and keel). The average coverage per digital image can be calculated by superimposin g 60 random dots and twenty randomly placed images may be used for the extrapol ation formula to estimate coverage for the total wetted surface area.

These figures may be used to establish a database w ith the fouling rate/ fouling index per vessel. This database can then be used to study the correlation between vessel activity and port residency time with increasing fo uling rate.34



### References

Anderson, C., M. Atlar, M. Callow, M. Candries, A. Milne and R. L. Townsin (2003). "The development of foul-release coatings for seago ing vessels." Proceedings of IMarEST - Part B - Journal of Marine Design and Operations (B4): 11-23. Bax, N., A. Williamson, M. Aguero, E. Gonzalez and W. Geeves (2003). "Marine invasive alien species: a threat to global biodiver sity." Marine Policy 27 : 313- 323. Chambers, L. D., K. R. Stokes, F. C. Walsh and R. J . K. Wood (2006). "Modern approaches to marine antifouling coatings." Surface & Coatings Technology 201 : 3642-3652. Conway, J. B. and L. P. Locke (1994). A final repor t on marine fouling and underwater hull cleaning in San Diego Bay

. Prepared for the Regional California Water Control Board, San Diego Region . 54pp. Coutts, A. D. M., K. M. Moore and C. L. Hewitt (200 3). "Ships’ sea-chests: an overlooked transfer mechanism for non-indigenous ma rine species?" Marine Pollution Bulletin 46 : 1510-1513. Coutts, A. D. M. and M. D. Taylor (2004). "A prelim inary investigation of biosecurity risks associated with biofouling on merchant vessel s in New Zealand." New Zealand Journal of Marine and Freshwater Research 38 : 215-229. Davidson, I., G. Ruiz and M. Sytsma (2006). Protoco l for sampling commercial vessel biofouling using a remotely operated vehicle (ROV)

. Report submitted to The California State Lands Commission , Aquatic Bioinvasion Research & Policy Institute. 20pp. Davidson, I. C., L. D. McCann, M. D. Sytsma and G. M. Ruiz (2008). "Interrupting a multi-species bioinvasion vector: The efficacy of i n-water cleaning for removing biofouling on obsolete vessels." Marine Pollution Bulletin 56 : 1538- 1544. Drake, J. M. and D. M. Lodge (2007). "Hull fouling is a risk factor for intercontinental species exchange in aquatic ecosys tems " Aquatic Invasions 2 (2): 121-131. Eiss, N. S. (1999). Durability Testing for Fouling Release Coatings

. 19990511 093

, Virginia Polytechnic Institute and State University , Department of Mechanical Engineering. 6pp. Falkner, M., N. Dobroski, C. Scianni, D. Gehringer and L. Takata (2009). 2009 Biennial Report on the California Marine Invasive S pecies Program Produced for the Calfornia State Legislature . California State Lands Commission Marine Facilities Division. 108pp. Floerl, O. and G. J. Inglis (2003). "Boat harbour d esign can exacerbate hull fouling." Austral Ecology 28 : 116-127. Floerl, O. and G. J. Inglis (2005). "Starting the i nvasion pathway: the interaction between source populations and human transport vect ors." Biological Invasions 7 : 589-606. Floerl, O., G. J. Inglis and B. J. Hayden (2005a). "A risk-based predictive tool to prevent accidental introductions of nonindigenous m arine species." Environmental Management 35 (6): 765-778.35

Floerl, O., G. J. Inglis and H. M. Marsh (2005b). " Selectivity in vector management: an investigation of the effectiveness of measures u sed to prevent transport of non-indigenous species." Biological Invasions 7 : 459-475. Galil, B. S. (2008). "Taking stock: inventory of al ien species in the Mediterranean sea." Biological Invasions 11 : 359-372. Geens, M. (2008). Ecospeed: Risk evaluation for the spread of "alien species" in surface water when using hard coatings on ship hull s

. Project Number 0058713. Report for the EU Life Project ECOTEC-STC LIFE06 ENV/B/000362 , Environmental Research Management. 17pp. GISP (2008). Marine Biofouling: An Assessment of Ri sks and Management Initiatives . Global Invasive Species Programme (GISP) and the UNEP Regional Seas Programme. 68pp. Godwin, L. S. (2003). "Hull fouling of maritime ves sels as a pathway for marine species invasions to the Hawaiian Islands." Biofouling: the Journal of Bioadhesion and Biofilm Research 19 : 123-131. Godwin, L. S., L. G. Eldredge and K. Gaut (2004). T he assessment of hull fouling as a mechanism for the introduction and dispersal of m arine alien species in the main Hawaiian Islands

. Bishop Museum Technical Report No. 28 . 122pp. Gollasch, S. (2002). "The importance of ship hull f ouling as a vector of species introductions into the North Sea." Biofouling: the Journal of Bioadhesion and Biofilm Research 18 (2): 105-121. Gollasch, S. and S. Nehring (2006). "National check list for aquatic alien species in Germany." Aquatic Invasions 1 : 245-269. Hoedt, F. E., J. H. Choat, J. J. Cruz, K. M. Neil a nd J. Collins (2001). Survey of the port of Weipa: port marine baseline surveys and sur veys for introduced marine pests . CRC Reef Research Centre & School of Marine Biolo gy and Aquaculture James Cook University. 43pp. Holland, R., T. M. Dugdale, R. Wetherbee, A. B. Bre nnan, J. A. Finlay, J. A. Callow and M. E. Callow (2004). "Adhesion and Motility of Fouling Diatoms on a Silicone Elastomer." Biofouling 20 (6): 323-329. Holm, E. R., E. G. Haslbeck and A. A. Horinek (2003 ). "Evaluation of brushes for removal of fouling from fouling-release surfaces, u sing a hydraulic cleaning device." Biofouling 19 (5): 297-305. Hopkins, G. A. and B. M. Forrest (2008). "Managemen t options for vessel hull fouling: an overview of risks posed by in-water cle aning." ICES Journal of Marine Science 65 : 811-815. Hutchings, P. A., R. W. Hilliard and S. L. Coles (2 002). "Species Introductions and Potential for Marine Pest Invasions into Tropical M arine Communities, with Special Reference to the Indo-Pacific." Pacific Science 56 (2): 223-233. Kerckhof, F., J. Haelters and S. Gollasch (2007). " Alien species in the marine and brackish ecosystem: the situation in Belgian waters " Aquatic Invasions 2 (2): 243-257. Lewis, J. (2002a). Hull Fouling as a Vector for the Translocation of Marine Organisms. Phase 1 Study - Hull Fouling Research

. Ballast Water Research Series: Report no. 14 , AMOG Consulting Marine Science and Ecology to Department of Agriculture, Fisheries and Forestry, Australia. 142pp. Lewis, J. (2002b). Hull Fouling as a Vector for the Translocation of Marine Organisms. Phase 3 The Significance of the Prospect ive Ban on Tributylin Antifouling Paints on the Introduction and Tansloca tion of Marine Pests in Australia

. Ballast Water Research Series: Report no. 15 , AMOG Consulting36 Marine Science and Ecology to Department of Agricul ture, Fisheries and Forestry, Australia. 133pp. Meyer, A. E., R. E. Baier and R. L. Forsberg (1995) . Degradation of Nontoxic Fouling-Release Coatings as a Result of Abrasion an d Long-Term Exposure

. Proceedings of The Fifth International Zebra Musse l and Other Aquatic Nuisance Organisms Conference : 337-342, Toronto, Canada Minchin, D. (2007). "A checklist of alien and crypt ogenic aquatic species in Ireland " Aquatic Invasions 2 : 341-366. Minchin, D. and S. Gollasch (2003). "Fouling and sh ips' hulls: how changing circumstances and spawning events may result in the spread of exotic species." Biofouling: the Journal of Bioadhesion and Biofilm Research 19 : 111-122. Mineur, F., M. P. Johnson and C. A. Maggs (2008). " Macroalgal introductions by hull fouling on recreational vessels: seaweeds and sailo rs." Environmental Management 42 : 667-676. Molnar, J. L., R. L. Gamboa, C. Revenga and M. D. S palding (2008). "Assessing the global threat of invasive species to marine biodive rsity " Frontiers in Ecology and the Environment 6 : 485-492. Naval Ships' Technical Manual (2006). Chapter 081. Waterborne underwater hull cleaning of Navy ships

. S9086-CQ-STM-010. Revision 5 , Naval Sea Systems Command. 68pp. Neil, K. M., R. Hilliard, B. Russell and P. Clark ( 2008). "Introduced marine species: Management arrangements of consideration for the To rres Strait." Continental Shelf Research 28 : 2317-2323. Nendza, M. (2007). "Hazard assessment of silicone o ils (polydimethylsiloxanes, PDMS) used in antifouling-/foul-release-products in the marine environment." Marine Pollution Bulletin 54 : 1190-1196. Otani, M., T. Oumi, S. Uwai, T. Hanyuda, R. E. Prab owo, T. Yamaguchi and H. Kawai (2007). "Occurrence and diversity of barnacle s on international ships visiting Osaka Bay, Japan, and the risk of their in troduction." Biofouling 23 : 277-286. Piola, R. F. and E. L. Johnston (2008). "The potent ial for translocation of marine species via small-scale disruptions to antifouling surfaces." Biofouling: the Journal of Bioadhesion and Biofilm Research 24 (3): 145-155. Preiser, H. S., C. P. Cologer and H. E. Achilles (1 975). Energy (Fuel) conservation through underwater removal and control of fouling o n hulls of navy ships

. Report 4543 (ADB007927) , David W. Taylor Naval Ship Research and Development Center. 53pp. Ricciardi, A. and J. Cohen (2007). "The invasivenes s of an introduced species does not predict its impact." Biological Invasions 9 : 309-315. Ruiz, G. M., P. W. Fofonoff, J. T. Carlton, M. J. W onham and A. H. Hines (2000). "Invasion of coastal marine communities in North Am erica: apparent patterns, processes, and biases." Annual Review of Ecology and Systematics 31 : 481- 531. Takata, L., M. Falkner and S. Gilmore (2006). Calif ornia State Lands Commission Report on Commercial Vessel Fouling in California: Analysis, Evaluation, and Recommendations to Reduce Nonindigenous Species Rel ease from the NonBallast Water Vector . California State Lands Commission. Marine Facilit ies Division. 83pp.37

Valkirs, A. O., B. M. Davidson, L. L. Kear, R. L. F ransham, A. R. Zirino and J. G. Grovhoug (1994). Environmental Effects from In-Wat er Hull Cleaning of Ablative Copper Antifouling Coatings

. Technical Document 2662 , Naval Command, Control and Ocean Surveillance Center RDT& E Division. 80pp. Van Rompay, B. (2008). Surface treated coatings and ship hull performance

. PCE 2008 : Paper 6, Hamburg Wijga, A., J. Romeijn, J. Tiesnitsch, S. Rotteveel and R. Berbee (2008). Biocide-free antifouling for ships. Emissions from the underwate r coating 'Ecospeed' (English Translation)

. Report for the EU Life Project ECOTEC-STC LIFE06 ENV/B/000362 , Dutch Ministry of Transport, Public Works and Wat er Management. Directorate-General for Public Works an d Water Management. 34pp. Willemsen, P. R. (2005). "Biofouling in European aq uaculture: is there an easy solution?" European Aquaculture Society Special Publications 35 : 82-87. Woods, C., O. Floerl, I. Fitridge, O. Johnston, K. Robinson, D. Rupp, N. Davey, N. Rush and M. Smith (2007). Evaluation of the seasona l efficacy of hull cleaning methods Final Biosecurity New Zealand Technical Report for Project ZBS2005-22 , National Institute of Water and Atmospheric Resea rch. 119pp. Woods Hole Oceanographic Institution (1952). Marine Fouling and its Prevention

. Annapolis, Maryland, US Naval Institute.38



### Appendix I. Figures of increasing FR

The figures have been taken directly from the Naval Ships’ Technical Manual for illustrative and contemplative purposes (Naval Ship s' Technical Manual, 2006).

FR 10. Over 30 Percent Of Area

FR 10. Over 100 Percent Of Area39 FR 20. Over 80 Percent Of Area

FR 30. Over 40 Percent Of Area40 FR 40. Over 20 Percent Of Area

FR 40. Over 30 Percent Of Area41 FR 40. Over 90 Percent Of Area

FR 50. Over 20 Percent Of Area42 FR 50. Over 40 Percent Of Area

FR 50. Over 100 Percent Of Area43 FR 60. Over 15 Percent Of Area

FR 60. Over 20 Percent Of Area44 FR 60. Over 90 Percent Of Area

FR 70. Over 20 Percent Of Area45 FR 70. Over 80 Percent Of Area

FR 80. Over 60 Percent Of Area46 FR 80. Over 80 Percent Of Area

FR 80. Over 90 Percent Of Area47 FR 90. Over 90 Percent Of Area

FR 90. Over 90 Percent Of Area48 FR 100. Over 50 Percent Of Area

FR 100. Over 100 Percent Of Area