Biodiversity characterisation and hydrodynamic consequences of marine fouling communities on marine renewable energy infrastructure in the Orkney Islands Archipelago,Scotland, UK

As part of ongoing commitments to produce electricity from renewable energy sources in Scotland, Orkney waters have been targeted for potential large-scale deployment of wave and tidal energy converting devices. Orkney has a well-developed infrastructure supporting the marine energy industry; recently enhanced by the construction of additional piers. A major concern to marine industries is biofouling on submerged structures, including energy converters and measurement instrumentation. In this study, the marine energy infrastructure and instrumentation were surveyed to characterise the biofouling. Fouling communities varied between deployment habitats; key species were identified allowing recommendations for scheduling device maintenance and preventing spread of invasive organisms. A method to measure the impact of biofouling on hydrodynamic response is described and applied to data from a wave-monitoring buoy deployed at a test site in Orkney. The results are discussed in relation to the accuracy of the measurement resources for power generation. Further applications are suggested for future testing in other scenarios, including tidal energy.     

Biofouling community composition across a range of environmental conditions and geographical locations suitable for floating marine renewable energy generation

Knowledge of biofouling typical of marine structures is essential for engineers to define appropriate loading criteria in addition to informing other stakeholders about the ecological implications of creating novel artificial environments. There is a lack of information regarding biofouling community composition (including weight and density characteristics) on floating structures associated with future marine renewable energy generation technologies. A network of navigation buoys were identified across a range of geographical areas, environmental conditions (tidal flow speed, temperature and salinity), and deployment durations suitable for future developments. Despite the perceived importance of environmental and temporal factors, geographical location explained the greatest proportion of the observed variation in community composition, emphasising the importance of considering geography when assessing the impact of biofouling on device functioning and associated ecology. The principal taxa associated with variation in biofouling community composition were mussels (Mytilus edulis), which were also important when determining loading criteria.     

Offshore wave energy generation devices: Impacts on ocean bio-environment

As the crisis of petroleum-based energy is aggravating and the carbon emission is elevating, the search and exploitation of renewable energy sources such as solar, wind and oceanic powers, are of global interest and underway in some developed countries. In western countries pioneering the oceanic energy utilization, wave is currently an attractive energy source due to the predictability and the ease to be absorbed into power grid. As wave-energy generators (WEGs) and the associated devices interact with the surrounding environment, they would have impacts on the biological components within the ecosystem in the vicinity of WEGs. However, the environmental effects of offshore WEGs on local fauna and flora have yet to be evaluated in a comprehensive way. This article discusses several aspects, including influence of offshore WEGs on marine macrofaunal communities, interactions between offshore WEGs and biofouling organisms, impacts of offshore WEGs on marine birds and of electromagnetic fields (EMFs) on marine animals as well as “artificial reef” effects. If precaution is taken with the planning and construction of offshore WEGs, and environmental monitoring is performed with operation of these devices, marine wave energy can become a desirable alternative to fossil fuels.     

Risk factors for fouling biomass: evidence from small vessels in Australia

Abstract

Invasive non-indigenous species (NIS) are a threat to marine biodiversity and marine reliant industries. Recreational vessels are recognised as an important vector of NIS translocation, particularly domestically. This paper reports on a novel application of multilevel modelling and multiple imputation in order to quantify the relationship between biofouling biomass (wet weight) and the vessel-level characteristics of recreational and fishing vessels. It was found that the number of days since the vessel was last cleaned strongly related to the biofouling biomass, yet differed dependent on vessel type. Similarly, the median number of trips undertaken was related to the biofouling biomass, and varied according to the type of antifouling paint (AF) used. No relationship was found between vessel size and biofouling biomass per sample unit. To reduce the spread of NIS, vessel owners should use an AF paint suitable to their vessel’s operational profile, and follow a maintenance schedule according to the paint manufacturer’s specifications.     

Propagule pressure determines recruitment from a commercial shipping pier

Artificial structures associated with shipping and boating activities provide habitats for a diverse suite of non-indigenous marine species. Little is known about the proportion of invader success in nearby waters that is attributable to these structures. Areas close to piles, wharves and piers are likely to be exposed to increasing levels of propagule pressure, enhancing the recruitment of non-indigenous species. Recruitment of non-indigenous and native marine biofouling taxa were evaluated at different distances from a large commercial shipping pier. Since artificial structures also represent a desirable habitat for fish, how predation on marine invertebrates influences the establishment of non-indigenous and native species was also evaluated. The colonisation of several non-indigenous marine species declined rapidly with distance from the structure. Little evidence was found to suggest that predators have much influence on the colonisation success of marine sessile invertebrate species, non-indigenous or otherwise. It is suggested that propagule pressure, not predation, more strongly predicts establishment success in these biofouling assemblages.     

Potential impacts of wave‐powered marine renewable energy installations on marine birds

One potential approach to combat the impacts of climate change is the expansion of renewable energy installations, leading to an increase in the number of wave‐powered marine renewable energy installations (MREIs). The consequences of increased use of these devices for birds are unknown. Here we describe the wave‐powered energy‐generating devices currently either operational or in development and review the potential threats and benefits of these to marine birds, their habitats and prey. Direct negative effects include risk of collision, disturbance, displacement and redirection during construction, operation and decommissioning. Above‐water collision is a particular concern with wind‐powered devices, but, because of their low profiles, the collision risk associated with wave‐powered devices is likely to be much lower. Conversely, wave devices also pose the novel threat of underwater collision. Wave‐energy‐generating devices may indirectly impact marine birds by altering oceanographic processes and food availability, with implications for trophic cascades. Through appropriate mitigation, wave‐powered MREIs offer the potential to enhance habitats. Direct positive effects may include provision of roosting sites, and indirect positive effects may include prey aggregation due to suitable substrates for sessile organisms or because they act as de facto protected areas. The cumulative effect of these could be the improvement and protection of foraging opportunities for marine birds. Recent studies have been critical of the methods used in the assessment of wind‐powered MREI impacts, which lack sufficient sample sizes, controls or pre‐development comparisons. Here we suggest solutions for the design of future studies into the effects of MREIs. Wave‐powered MREIs are certain to become part of the marine environment, but with appropriate planning, mitigation and monitoring they have the potential to offer benefits to marine birds in the future.     

The effect of vessel speed on the survivorship of biofouling organisms at different hull locations

This study used a specially designed MAGPLATE system to quantify the en route survivorship and post-voyage recovery of biofouling assemblages subjected to short voyages (<12 h) across a range of vessel speeds (slow, medium, fast; in the range 4.0–21.5 knots). The effect of hull location (bow, amidships and stern) was also examined. While no significant differences were evident in en route survivorship of biofouling organisms amongst hull locations, biofouling cover and richness were markedly reduced on faster vessels relative to slower craft. Therefore, the potential inoculum size of non-indigenous marine species and richness is likely to be reduced for vessels that travel at faster speeds (>14 knots), which is likely to also reduce the chances of successful introductions. Despite this, the magnitude of introductions from biofouling on fast vessels can be considered minor, especially for species richness where 90% of source-port species were recorded at destinations.     

Potential biocontrol agents for biofouling on artificial structures

The accumulation of biofouling on coastal structures can lead to operational impacts and may harbour problematic organisms, including non-indigenous species. Benthic predators and grazers that can supress biofouling, and which are able to be artificially enhanced, have potential value as augmentative biocontrol agents. The ability of New Zealand native invertebrates to control biofouling on marina pontoons and wharf piles was tested. Caging experiments evaluated the ability of biocontrol to mitigate established biofouling, and to prevent fouling accumulation on defouled surfaces. On pontoons, the gastropods Haliotis iris and Cookia sulcata reduced established biofouling cover by >55% and largely prevented the accumulation of new biofouling over three months. On wharf piles C. sulcata removed 65% of biofouling biomass and reduced its cover by 73%. C. sulcata also had better retention and survival rates than other agents. Augmentative biocontrol has the potential to be an effective method to mitigate biofouling on marine structures.     

Mini-review: Assessing the drivers of ship biofouling management – aligning industry and biosecurity goals

Biofouling exerts a frictional and cost penalty on ships and is a direct cause of invasion by marine species. These negative consequences provide a unifying purpose for the maritime industry and biosecurity managers to prevent biofouling accumulation and transfer, but important gaps exist between these sectors. This mini-review examines the approach to assessments of ship biofouling among sectors (industry, biosecurity and marine science) and the implications for existing and emerging management of biofouling. The primary distinctions between industry and biosecurity in assessment of vessels biofouling revolve around the resolution of biological information collected and the specific wetted surface areas of primary concern to each sector. The morphological characteristics of biofouling and their effects on propulsion dynamics are of primary concern to industry, with an almost exclusive focus on the vertical sides and flat bottom of hulls and an emphasis on antifouling and operational performance. In contrast, the identity, biogeography, and ecology of translocated organisms is of highest concern to invasion researchers and biosecurity managers and policymakers, especially as it relates to species with known histories of invasion elsewhere. Current management practices often provide adequate, although not complete, provision for hull surfaces, but niche areas are well known to enhance biosecurity risk. As regulations to prevent invasions emerge in this arena, there is a growing opportunity for industry, biosecurity and academic stakeholders to collaborate and harmonize efforts to assess and manage biofouling of ships that should lead to more comprehensive biofouling solutions that promote industry goals while reducing biosecurity risk and greenhouse gas emissions.     

Who is where in the Plastisphere,and why does it matter?

To fully understand how plastic is affecting the ocean, we need to understand how marine life interacts directly with it. Besides their ecological relevance, microbes can affect the distribution, degradation and transfer of plastics to the rest of the marine food web. From amplicon sequencing and scanning electron microscopy, we know that a diverse array of microorganisms rapidly associate with plastic marine debris in the form of biofouling and biofilms, also known as the “Plastisphere.” However, observation of multiple microbial interactions in situ, at small spatial scales in the Plastisphere, has been a challenge. In this issue of Molecular Ecology Resources, Schlundt et al. apply the combination labelling and spectral imaging – fluorescence in situ hybridization to study microbial communities on plastic marine debris. The images demonstrate the colocalization of abundant bacterial groups on plastic marine debris at a relatively high taxonomic and spatial resolution while also visualizing biofouling of eukaryotes, such as diatoms and bryozoans. This modern imaging technology provides new possibilities to address questions regarding the ecology of marine microbes on plastic marine debris and describe more specific impacts of plastic pollution in the marine food webs.     

Evaluation of dihydrooroidin as an antifouling additive in marine paint

Methods used to deter biofouling of underwater structures and marine vessels present a serious environmental issue and are both problematic and costly for government and commercial marine vessels worldwide. Current antifouling methods include compounds that are toxic to aquatic wildlife and marine ecosystems. Dihydrooroidin (DHO) was shown to completely inhibit Halomonas pacifica biofilms at 100 μM in a static biofilm inhibition assay giving precedence for the inhibition of other marine biofilm-forming organisms. Herein we present DHO as an effective paint-based, non-cytotoxic, antifouling agent against marine biofouling processes in a marine mesocosm.     

On microalgal settlements and the sluggish development of marine biofouling in Port Blair waters,Andamans

Settlement of microalgae was investigated on Perspex®, aluminium and zinc coupons immersed in Port Blair Bay waters for over 3 months. Commencement of fouling was exceptionally slow, and few microalgae were found until 14 days. Settlement occurred thereafter, and 47 microalgal species contributed to the fouling. The dominant forms belonged to the genera Navicula and Nitzschia, whereas Coscinodiscus eccentricus, Gyrosigma balticum and Trichodesmium erythraeum also accounted for high proportions of the settlements. The dominance of Nitzschia sigma was particularly marked on zinc coupons, suggesting an ability by the organism to resist toxicity. Settlement of both centric and pennate diatoms was observed in the early and mid periods, and absolute dominance of the pennate diatoms subsequently. The fouling mass was low even after 103 days, and it is speculated that strong ultraviolet radiation might be the prime reason for the sluggish development of marine biofouling in these oceanic island waters.     

Non-chemical biofouling control in heat exchangers and seawater piping systems using acoustic pulses generated by an electrical discharge

Acoustic pulses generated by an electrical discharge (pulsed acoustics) were investigated as a means for biofouling control in two test formats, viz. a 5/8" outside diameter titanium tube and a mockup heat exchanger. The pulsed acoustic device, when operated at 17 kV, demonstrated 95% inhibition of microfouling over a 20 ft length of titanium tube over a 4-week period, comparable to chlorination in combination with a high-velocity flush. The pulsed acoustic device inhibited microfouling over a downstream distance of 15 ft, therefore, a single pulsed acoustic device is theoretically capable of protecting at least 30 ft of tube from microfouling (15 ft on either side of the device). A correlation between acoustic intensity in the frequency range 0.01-1 MHz and the level of biofouling inhibition was observed. The threshold acoustic intensity for microfouling inhibition was determined for this frequency range. It was also observed that the orientation of the device is critical to obtaining microfouling inhibition.     

Making the Case for Marine Spatial Planning in the Maltese Islands

Marine spatial planning (MSP) has been gaining in stature recently as an ecosystem-based tool for the management of marine space that promotes the sustainable and optimal use of resources with minimal stakeholder conflicts. Malta is the quintessential maritime nation, with a disproportionately large marine area compared to its terrestrial area. Nonetheless, its limited coastline, a considerable portion of which is inaccessible, poses inevitable conflicts between multiple marine activities and designations, including aquaculture, fishing, bunkering, coastal tourism, navigation, renewable energy installations, conservation of biological diversity and protected areas (on ecological criteria). This article makes the case to implement MSP-based policies and an applicable legal framework in the Maltese Islands.     

Effects of surface texture and interrelated properties on marine biofouling: a systematic review

This systematic review examines effects of surface texture on marine biofouling and characterizes key research methodologies. Seventy-five published articles met selection criteria for qualitative analysis; experimental data from 36 underwent quantitative meta-analysis. Most studies investigated fouling mechanisms and antifouling performance only in laboratory assays with one to several test species. Textures were almost exclusively a single layer of regularly arranged geometric features rather than complex hierarchical or irregular designs. Textures in general had no effect or an inconclusive effect on fouling in 46% of cases. However, effective textures more often decreased (35%) rather than increased (19%) fouling. Complex designs were more effective against fouling (51%) than were regular geometric features (32%). Ratios of feature height, width, or pitch to organism body length were significant influences. The authors recommend further research on promising complex and hierarchical texture designs with more test species, as well as field studies to ground-truth laboratory results.     

Microbial characteristics of marine sediments in bathing area along Pesaro-Gabicce coast (Italy): a preliminary study

AIMS: This paper evaluates the presence of human pathogen micro-organisms in marine sediments in a coastal area suitable for bathing. In addition, the grain size analysis was performed in order to correlate the characteristics of the sediments and the microbial content. METHODS AND RESULTS: The samples were collected in two small bays along the central Adriatic coast, where breakwaters had been built for the purpose of halting marine erosion. Faecal contamination indicators, Salmonella and Vibrio species, enteric viruses were investigated using standard techniques for isolation and identification. The grain size was determined using calibrated sieves and 'Sedigraph' device. In some samples, the faecal contamination indices overstepped legislative limits. Salmonella was never found. Vibrio and enteric viruses were isolated: the micro-organisms were preferentially abundant in fine sediments. CONCLUSIONs: Marine sediments can represent an important reservoir of allochthonous and marine micro-organisms and the microbial charge correlates with the characteristics of the sediments. SIGNIFICANCE AND IMPACT OF THE STUDY: This study indicates that it is important to analyse marine sediments before defining the quality of coastal areas.     

Non-Chemical biofouling control in heat exchangers and seawater piping systems using acoustic pulses generated by an electrical discharge

Acoustic pulses generated by an electrical discharge (pulsed acoustics) were investigated as a means for biofouling control in two test formats, viz. a 5/8" outside diameter titanium tube and a mockup heat exchanger. The pulsed acoustic device, when operated at 17 kV, demonstrated 95% inhibition of microfouling over a 20 ft length of titanium tube over a 4-week period, comparable to chlorination in combination with a high-velocity flush. The pulsed acoustic device inhibited microfouling over a downstream distance of 15 ft, therefore, a single pulsed acoustic device is theoretically capable of protecting at least 30 ft of tube from microfouling (15 ft on either side of the device). A correlation between acoustic intensity in the frequency range 0.01-1 MHz and the level of biofouling inhibition was observed. The threshold acoustic intensity for microfouling inhibition was determined for this frequency range. It was also observed that the orientation of the device is critical to obtaining microfouling inhibition.     

Evaluation of the sea anemone Anthothoe albocincta as an augmentative biocontrol agent for biofouling on artificial structures

Augmentative biocontrol, defined as the use of indigenous natural enemies to control pest populations, has not been explored extensively in marine systems. This study tested the potential of the anemone Anthothoe albocincta as a biocontrol agent for biofouling on submerged artificial structures. Biofouling biomass was negatively related to anemone cover. Treatments with high anemone cover (>35%) led to significant changes in biofouling assemblages compared to controls. Taxa that contributed to these changes differed among sites, but included reductions in cover of problematic fouling organisms, such as solitary ascidians and bryozoans. In laboratory trials, A. albocincta substantially prevented the settlement of larvae of the bryozoan Bugula neritina when exposed to three levels of larval dose, suggesting predation as an important biocontrol mechanism, in addition to space pre-emption. This study demonstrated that augmentative biocontrol using anemones has the potential to reduce biofouling on marine artificial structures, although considerable further work is required to refine this tool before its application.     

Effects of marine reserve characteristics on the protection of fish populations: a meta-analysis

Meta-analyses of published data for 19 marine reserves reveal that marine protected areas enhance species richness consistently, but their effect on fish abundance is more variable. Overall, there was a slight (11%) but significant increase in fish species number inside marine reserves, with all reserves sharing a common effect. There was a substantial but non-significant increase in overall fish abundance inside marine reserves compared to adjacent, non-reserve areas. When only species that are the target of fisheries were considered, fish abundance was significantly higher (by 28%) within reserve boundaries. Marine reserves vary significantly in the extent and direction of their response. This variability in relative abundance was not attributable to differences in survey methodology among studies, nor correlated with reserve characteristics such as reserve area, years since protection, latitude nor species diversity. The effectiveness of marine reserves in enhancing fish abundance may be largely related to the intensity of exploitation outside reserve boundaries and to the composition of the fish community within boundaries. It is recommended that studies of marine reserve effectiveness should routinely report fishing intensity, effectiveness of enforcement and habitat characteristics.     

Sounding out pests: the potential of hydroacoustics as a surveillance and compliance tool in aquatic biosecurity

Shipping is the main method for goods transportation, accounting for approximately 60% of all global trade. Biofouling of these shipping vessels is a critical pathway for the introduction of non-indigenous species (NIS) across the world’s oceans. In order to reduce the likelihood of NIS introductions, appropriate biosecurity mechanism need to be in place, including maintaining high standards in vessel hygiene, such as zero secondary biofouling. Development of methodologies that can accurately quantify vessel biofouling without impeding maritime operations, while simultaneously providing effective biosecurity for the marine environment and resources, and mitigation of introduced marine pests would be highly advantageous. This study tests such a methodology. We conduct a proof-of-concept study that uses hydroacoustics to quantify the biofouling on a vessel’s hull, using surrogates for a vessel hull and biofouling. Based on a simple off-the-shelf single beam echosounder, the method was able to visually detect and quantify various biofouling mimics (ranging in height from 10 to 200 mm in height) at a slow tow speed (0.5 m/s). The efficacy of the hydroacoustic method was influenced by the movement of the echosounder, with the discriminating capability reduced to the detection of only larger mimics as the speed of movement increased. With further development, the use of hydroacoustics could become a viable biosecurity surveillance option for the mitigation of introduced marine pest incursions.