Ecological Management factors associated with Wind Farms, Oil Rigs and other Off-Shore Marine Structures; all serviced

1. Ecological Management factors associated with Wind Farms, Oil Rigs and other Off-Shore Marine Structures; all serviced by large vessels.

2. Introduction: WINDFARMS • Wind power is growing at the rate of 30% annually, with a worldwide installed capacity of 121,000 megawatts (MW) in 2008, and is widely used in European countries and the United States. • Wind Farm Types • Onshore • Offshore and Nearshore • Offshore wind farms are generally considered to be ten kilometres or more from land. • Nearshore wind farms are on land within three kilometres from the coastline or on water within ten kilometres of land.

3. Transition piece and foundations (under water) require a Cathodic Protection (CP)design system (sacrificial anodes) and a paint system.

4. Corrosion: ALL OFF-SHORE MARINE STRUCTURES(INCLUDING WIND FARMS) • Greater problem of access during bad weather, and greater expense when replacing larger main components. Transition piece, foundations etc require a Cathodic Protection (CP)design system (sacrificial anodes) and a paint system. • Galvanic or sacrificial anodes are designed with a more negative electrochemical potential than the metal of the structure. The voltage potential of the steel surface is polarised (pushed) more negative until the surface of the structure has a uniform voltage potential and the driving force for the corrosion reaction is halted. The sacrificial anode continues to corrode (sacrifice), which consumes the anode material until it requires replacement. The polarisation is caused by the current flow from the anode to the cathode. The driving force for the CP current flow is the difference in electrochemical voltage potential between the anode and the cathode. • Galvanising (also known as Hot Dip Galvanising) is the process of applying a zinc coating to steelwork which prevents corrosion of the protected metal by forming a protective physical barrier. • Benefits: Protection - Coverage - Coating toughness

5. Protecting against Marine Biofouling • Marine fouling and biofouling can form on structures at all depths and temperatures and is commonly found in vessel's seawater cooling systems. • A common Anti-fouling system consists of two types of anodes, a Copper alloy rod to prevent fouling and Aluminium or Ferrous alloy rod to prevent corrosion. • An anti-fouling anode, once fitting requires little maintenance and is not damaging to the environment. As a thin surface over the cathodic structure It erodes taking away the fouling organisms with it.

6. Hull Anodes on service vessels Coatings are the first barriers to protect vessel hulls against corrosion. Due to microscopic pinhole defects in the coating and damage to it whilst in service localised pitting will occur. Hull/flush mounted anodes are used to complement the coating at areas of exposed steel prolonging the life of the coating. Hull anodes are also employed to reduce corrosion rates on areas of the hull that are local to propellers and the propellers themselves. Alloys of Zinc, Aluminium and Magnesium with the necessary trace elements to provide correct performance are used for the manufacturing of Sacrificial anodes Even with correctly designed cathodic protection systems marine fouling is a constant problem.

7. Anti-fouling paints and devices. Mechanical: • blasting devices e.g. sand abrasion, • heated water in pipes and at power stations; different species have different tolerance, • metal chains or foam skirting and other structures that move up and down girders, piling structures, sometimes spinning • ultra-sonic or low frequency resonators and vibrating structures to prevent settlement • energizing a piezofilm layer carried on the outside of a vessel or structure to cause mechanical vibration of the layer. This can be developed into a self- powered system. A system including an electroded layer of piezoelectric material mounted in a position to be stressed and strained and to then produce an alternating current (a.c.) voltage. This piezoelectric material being coupled to voltage rectifying means for converting the a.c. energy produced by the piezoelectric material when stressed and strained, into direct current (d.c.) energy for charging a battery; and a direct current to alternating current converter means coupled between the battery and the piezoelectric material for converting the direct current energy stored in the battery into an alternating current signal having a preselected frequency and applying the a.c. signal to the piezoelectric material for causing the piezoelectric material to vibrate at a rate proportional to the preselected frequency, to prevent settlement of fouling organisms.

8. Anti-fouling paints and devices. Coating: • anti fouling paints with toxic metals e.g. Tin, Copper or Lead; very toxic to all life in the environment ; use banned. • these toxic metals micro-encapsulated for slower release; still toxic • Non toxic shiny slippery plastics and resins, some slowly breaking down and continuously forming new surfaces; may slow down fouling but do not stop it. • superhydrophobicity (i.e. extreme non-wettability) research aimed at fabricating superhydrophobic surfaces by tailoring their chemical nature and physical appearance (i.e. substratum texture) . The aim is the formation of responsive/‘‘smart’’ surfaces, which adjust their physico-chemical properties to variations in some outside physical stimulus, including light, temperature, electric field, or solvent. Finally, implications of tailoring the surface chemistry, texture, and responsiveness of surfaces on the design of effective marine fouling coatings are being considered. • Utilising Bioactive Compounds from marine invertebrates (e.g. sponges) algae, and microorganisms, (produce to enhance their competitivity for space or to prevent other organisms settling on their surfaces and overgrowing them). • Cyanobacteria produce a variety of bioactive metabolites that may have allelochemical functions in the natural environment, such as in the prevention of fouling by colonising organisms. Cyanobacterial metabolites have the potential for use in antifouling technology, since they show antibacterial, antialgal, antifungal and antimacrofouling properties which could be expoited in the prevention of biofouling on man-made substrata in the aquatic environment. A survey of antibiotic compounds with antifouling potential revealed more than 21 different antifouling substances from 27 strains of cyanobacteria.

9. Anti-fouling paints and devices Electrical: • Galvanic or sacrificial anodes designed with a more negative electrochemical potential than the metal of the structure (as described previously), which gradually erode dislodging recently settled fouling organisms. • intermittent pulses of electric currents at various voltages along submerged metal structures, often between short strips; some kill organisms but some work by causing thin layers of the metal to slowly fall off with time in a process similar to sacrificial anodes also dislodging recently settled fouling organisms. • an anti-fouling system that includes a pair of electrodes positioned apart and a means for supplying an electrical current to the electrodes; The electrolysis of sea water produces toxic agents such as chlorine and sodium hypochlorite adjacent the aquatic body that removes barnacles, algae, fungi and other marine growths. Further, the electrodes require regular maintenance, which may be difficult.

10. Combating Marine Fouling • Prevention of marine fouling • Study Theory of processes involved in marine fouling, to try and better understand how to control it and limit its destructive powers and in some cases utilise it for benefit.

11. Best Practice regarding Off Shore Marine structures • Spatial planning is important: to get the best sites with the least damage to the environment, pre –production (GIS studies) • Environmental Impact Assessments (EIAs) are necessary pre- and post-production • Disposal or amelioration of structures / sites must be considered early for the post-production phase.

14. Notes on Fouling A. Marine

15. Marine Fouling 1. Artificial substrates mimic natural ones when chosen properly 2. Non comparability between localities • Workers vary substrate size, materials & observation techniques; select for different animals; where possible keep features the same. • Rarely can colonisation patterns on identical substrates from different latitudes be compared. 3. Initial rates of increase in number of sessile species accumulating with time are inversely related to latitude (in Northern Hemisphere: tropics to arctic); however eventually have higher fouling in temperate versus tropical latitudes. 4. Initial dominance by colonial organisms changes to dominance by solitary organisms in northern hemisphere, in contrast to tropical localities, where it is the opposite (e.g. ending with colonial corals). • Solitary: sexual reproduction more common. • Colonial: asexual reproduction more common.

16. Marine Fouling 5. Replicability • Diversity is usually constant in an area • Less variability among species totals than among species identities (species substitution) • Trophic dynamics the same: filter feeders are the most common • 6 – 10 panels seem reasonable: benefits of larger sample size diminish quite rapidly beyond this • Although compositional differences exist between individual panels & may well be the result of presence or absence of particular species, quantitative descriptions of the colonisation process can accommodate these variations, while still portraying many of the general aspects of colonisation.

17. Marine Fouling 6. Seasonal difference in colonisation • Rate of colonisation increases in late spring; is low in winter: • mussels may be an exception (highest in February / March). 7. In tropical localities colonial organisms eventually predominate but it takes considerably longer (14 – 26 months) for them to emerge as dominants over solitary species.

18. B. Protozoan Colonisation (Fresh Water):(but probably the same in the marine environment for most species) • There is an initial non interactive stage, followed by a longer interactive stage. • Initial island colonisation is essentially a non-interactive process, primarily influenced by the dispersal capacities and extinction potentials of the colonising organisms. • With the establishment of an equilibrium species number, interactive processes such as competition and predation take precedence in determining the island’s species composition. • The island assemblage soon manifests the characteristics of an autonomous community capable of maintaining its integrity in the face of environmental change. (Ref. Zoology, Mac Arthur Wilson). • Use plates as a sampling device: a. may retrieve plates before equilibrium (where the numbers of individuals of species are increasing) do not get very characteristic or repeatable results b. or at equilibrium (where the numbers of individuals of species coming in are the same as numbers leaving) get associated species assemblage. c. Appropriate immersion time will vary under different environmental conditions, making comparable sample days difficult to choose.

19. B. Protozoan Colonisation (Fresh Water): 2. Because the effectiveness of an artificial substrate sampler can be affected differently by the factors of : • Substrate size, • Position in space, and • immersion time, • in a particular environment, it is preferable to: a. hold size constant when comparing specific systems, b. position substrates so they act as habitat islands, (need care in siting them in characteristic regions), c. monitor colonisation through time, as an alternative to one-time sampling. A time–dependant process is then analysed as the indicator of natural community structure. 3. Need sufficient size (5 X 7.5 X 6.5 cm) to collect the majority of species (of Protozoa) from one location • too large : is too time consuming & plate may become too heavy. • too small : can sample poor competitors.

20. A.Marine Fouling 8. Pioneer species (r-selection strategies): have high reproductive rates; live in regions with unpredictable resources in unsaturated, non-equilibrium communities; e.g. solitary ascidians (Cliona), more effort in reproduction. 9.Later species (K-selection strategies): lower reproductive rates, density dependant mortality, specialised for habitat; e.g. solitary ascidians, e.g. thicker tunic (Ascidia), less reproductive effort. 10. Interactive equilibrium succeeded by an "assortive" equilibrium: consists of a combination of species that are either better adapted to the conditions of the local environment, or else were able to coexist longer with the particular set of species among whom they find themselves. Simberloffexpanded this concept of multiple equilibria to include evolutionary and taxon cycle equilibria. He predicted that non-interactive and interactive (including assortive) would be achieved on an ecological time scale, and evolutionary and taxon cycle equilibria would occur on an evolutionary time scale.

21. 11. Substrate angle and predation as determinants in fouling Succession Harris and Irons, working with sub-littoral populations in New Hampshire, tested the hypothesis that ‘substrate angle and predation are determinants in fouling community succession’ (vertical and lower horizontal surfaces would be expected to have no crab predators, but may have starfish and fish predators). The primary experiment involved arrays of 1/10-m2plexiglass panels set up in horizontal and vertical planes against and away from the wall of a wooden crib to facilitate and inhibit access by sea stars, crabs and wrasses. Two replicates of the experiments were established in summer and winter, respectively, to test for temporal effects on long-term succession. The results showed both substrate angle and predation effects, but no seasonal effects. • Siltation and predation interacted to exclude most species from the upper horizontal surfaces, the exception being Mytilusedulis(mussels) in predator-free systems. • Lower horizontal surfaces had higher diversities and more species with upright growth forms than vertical surfaces. • Mussels dominated most surfaces on predator-free panels, regardless of substrate angle. • Predation effects included keystone predation (on mussels), larval filter (by tunicates), and cropping of colonial species (hydroids and ectoprocts); in each case, the survival and distribution of species had been altered. • Inter-phyletic competitive interactions were documented and the results suggested that size, longevity and a living surface layer are important mechanisms enhancing the competitive abilities of encrusting colonial forms such as sponges.