Williamson, L.D., Scott, B.E., Laxton, M., Bachl, F., Illian, J., Brookes, K., and Thompson, P.
Marine Mammal Science In Press (2021)
Understanding spatiotemporally varying animal distributions can inform ecological understanding of species’ behavior (e.g., foraging and predator/prey interactions) and support development of management and conservation measures. Data from an array of echolocation-click detectors (C-PODs) were analyzed using Bayesian spatiotemporal modeling to investigate spatial and temporal variation in occurrence and foraging activity of harbor porpoises (Phocoena phocoena) and how this variation was influenced by daylight and presence of bottlenose dolphins (Tursiops truncatus). The probability of occurrence of porpoises was highest on an offshore sandbank, where the proportion of detections with foraging clicks was relatively low. The porpoises’ overall distribution shifted throughout the summer and autumn, likely influenced by seasonal prey availability. Probability of porpoise occurrence was lowest in areas close to the coast, where dolphin detections were highest and declined prior to dolphin detection, leading potentially to avoidance of spatiotemporal overlap between porpoises and dolphins. Increased understanding of porpoises’ seasonal distribution, key foraging areas, and their relationship with competitors can shed light on management options and potential interactions with offshore industries.
Susini, I., & Todd, V.L.G
The ecosystem modelling complex ‘Ecopath with Ecosim’ has been implemented extensively in the field of marine science; however, despite its widespread application, descriptions of its functionality remain arcane in the literature. This study conducts an evaluation of the software’s prediction capacity using eight published Ecopath models. Response of six ecosystem-status indicators to four basic input variables to which imprecision had been added was investigated. Kempton’s Q Index and total system throughput emerged as the most consistently responsive parameters. Moreover, input biomass was identified as a ‘high-leverage’ parameter, its influence on outputs being greater than that exerted by any other input variable. This study constitutes one of the first comprehensive investigations of the response of selected outputs to imprecise input values, and provides sufficient basis to warrant a sensitivity assessment of the software, as well as introduction of a dedicated tool to perform such a task within Ecopath with Ecosim.
Todd, V.L.G., Williamson, L.D., Jiang, J., Cox, S.E., Todd, I.B., and Ruffert, M
Acoustic Deterrent Devices (ADDs) are used worldwide to deter pinnipeds from predating fish-aquaculture facilities. Desk-based noise-propagation modelling of six commercial ADD models, and a ‘fictional’ ADD was performed, the latter involving alternating source level, frequency, duty cycle, noise-exposure duration, and number of ADDs active simultaneously. Potential auditory impacts on marine mammals were explored using the Southall et al. (2019) criteria. Depending on operational characteristics, real ADDs were predicted to cause Temporary Threshold Shift (TTS) to Very High Frequency (VHF) cetaceans at ranges of 4–31 km, and a single fictional device operating at the highest outputs tested was predicted to cause TTS to VHF cetaceans at up to 32 km. Cumulative effects of 23 real fish-farm ADDs produced noise across large swathes of the Inner-Hebrides. The single variable causing greatest reduction in potential impact to marine mammals from fictional ADDs was SL.
Vedor, M., Queiroz, N., Mucientes, G., Couto, A., da Costa, I., dos Santos, A., Vandeperre, F., Fontes, J., Afonso, P., Rosa, R., Humphries, N.E., Sims, D.W.
Climate-driven expansions of ocean hypoxic zones are predicted to concentrate pelagic fish in oxygenated surface layers, but how expanding hypoxia and fisheries will interact to affect threatened pelagic sharks remains unknown. Here, analysis of satellite-tracked blue sharks and environmental modelling in the eastern tropical Atlantic oxygen minimum zone (OMZ) shows shark maximum dive depths decreased due to combined effects of decreasing dissolved oxygen (DO) at depth, high sea surface temperatures, and increased surface-layer net primary production. Multiple factors associated with climate-driven deoxygenation contributed to blue shark vertical habitat compression, potentially increasing their vulnerability to surface fisheries. Greater intensity of longline fishing effort occurred above the OMZ compared to adjacent waters. Higher shark catches were associated with strong DO gradients, suggesting potential aggregation along suitable DO gradients contributed to habitat compression and higher fishing-induced mortality. Fisheries controls to counteract deoxygenation effects on shark catches will be needed as oceans continue warming.
Williamson, B.J., Blondel, P., Williamson, L.D., and Scott, B.E.
Changes in animal movement and behaviour at fine scales (tens of metres) in immediate proximity to tidal stream turbine structures are largely unknown and have implications for risks of animal collision with turbine blades. This study used upward-facing multibeam echosounder data to detect and track animal movement comprising fish, diving seabirds, and marine mammals. Measurements over spring-neap tidal cycles at a turbine structure (no blades present) are compared to a neighbouring reference area with no structure and comparable conditions, with measurements consecutive in time to maximize comparability.
The majority of tracked animals (93.4% around turbine structure and 99.1% without turbine structure) were observed swimming against the flow, with 87.5% and 97.8%, respectively, making ground and showing capability of manoeuvring in tidal stream flow speeds. Track tortuosity increased around the turbine structure compared to the reference site, particularly in the wake and at low flow speeds, indicating animal station-holding or milling behaviour. These data also evidence the benefits of multibeam echosounders to measure animal movement through larger measurement volumes rather than relying on single-beam echosounders to measure animal presence alone, including to avoid large biases overestimating the size of schools swimming against the flow measured by time-in-beam.
Todd, V.L.G., Susini, I., Williamson, L.D., Cox, S.E., Todd, I.B., McLean, D.L., and Macreadie, P.I.
Offshore Oil and Gas (O&G) infrastructure affords structurally complex hard substrata in otherwise featurless areas of the seafloor. Opportunistically collected industrial ROV imagery was used to investigate the colonization of a petroleum platform in the North Sea 1–2 years following installation. Compared to pre-construction communities and pioneering colonizers, we documented 48 additional taxa, including a rare sighting of a pompano (Trachinotus ovatus). The second wave of motile colonizers presented greater diversity than the pioneering community. Occurrence of species became more even over the 2 years following installation, with species occurring in more comparable abundances. No on-jacket sessile taxa were recorded during first-wave investigations; however, 17 sessile species were detected after 1 year (decreasing to 16 after 2). Motile species were found to favour structurally complex sections of the jacket (e.g. mudmat), while sessile organisms favoured exposed elements. Evidence of on-jacket reproduction was found for two commercially important invertebrate species – common whelk (Buccinum undatum) and European squid (Loligo vulgaris). Moreover, abundance of larvae-producing species experience an 8.5-fold increase over a 2-year period compared to baseline communities. These findings may have implications for decommissioning and resource-management strategies, suggesting that a case-by-case reviewing approach should be favoured over the most common “one size fits all”.
Todd, VLG., Williamson, LD, & Jiang, J., Cox, S.E., Todd, I.B., & Ruffert, M
Little is known about localized, near-field soundscapes during offshore hydrocarbon drilling campaigns. In the Dogger Bank, North Sea, underwater noise recordings were made 41–60 m from the drill stem of the Noble Kolskaya jack-up exploration drilling rig. The aims were to document noise received levels (RLs) and frequency characteristics of rig-associated near-field noise. The rig produced sound pressure levels (SPLs) of 120 dB re 1 μPa in the frequency range of 2–1400 Hz. Over transient periods, RLs varied by 15–20 dB between softest (holding) and noisiest (drilling) operations. Tonal components at different frequencies varied with depth. Support vessel noise was significantly louder than the jack-up rig at frequencies <1 kHz, even in its noisiest “boulder-drilling” phase, though radiated noise levels were higher above 2 kHz. Rig SPLs fell rapidly above 8 kHz. Marine mammals, such as harbor porpoise (Phocoena phocoena) forage regularly near offshore oil and gas rigs and platforms, and it is predicted that animals experience different noise regimes while traversing the water column and can potentially detect the higher-frequency components of drilling noise to a distance of 70 m from the source; however, while levels were unlikely to cause auditory injury, effects on echolocation behavior are still unknown.
Todd, V.L.G., Lazar, L., Williamson, L.D., Peters, I., Cox, S.E., Todd, I.B.
In oceans and seas worldwide, an increasing number of end-of-life anthropogenic offshore structures (e.g., platforms, pipelines, manifolds, windfarms, etc.) are facing full or partial removal. As part of the decommissioning process, studies on potential importance of subsea infrastructure to marine megafauna (defined as: cetaceans, pinnipeds, sirenians, large fish – such as sharks, rays, billfishes, and tuna, as well as marine reptiles, and seabirds) are lacking. Dedicated scientific Remotely Operated Vehicle (ROV) surveys around offshore installations are rare, but there is a wealth of archived industrial data and noteworthy species sightings posted publicly on various social media platforms. This study used routine, incidentally collected ROV (n = 73) and commercial diver (n = 9) video recordings spanning 1998–2019 globally. Data were gathered directly from industrial partners (n = 36) and the public domain (YouTube; n = 46) to provide an account of marine megafauna presence and potential feeding behavior in the near-visible vicinity of subsea anthropogenic structures. A total of 79 video clips and 3 still images of marine megafauna near offshore structures were examined, resulting in 67 individual sightings and 16 sub-sightings (in which an individual was recorded within the same day). At least 178 individuals were identified to a minimum of 17 species of marine megafauna, amounting to a total (combined) sighting duration of 01:09:35 (hh:mm:ss). Results demonstrated proximate presence of marine megafauna (many of which are threatened species) to anthropogenic structures, with most animals displaying foraging or interaction behaviors with the structures. Observations included the deepest (2,779 m) confirmed record of a sleeper shark (Somniosus spp.) and the first confirmed visual evidence of seals following pipelines. These ROV observations demonstrate a latent source of easily accessible information that can expand understanding of marine megafauna interactions with offshore anthropogenic infrastructure. Consequently, other workers in this field should be encouraged to re-analyze archived datasets, commence further collaborative research projects with industrial partners, and/or expand Internet search terms to additional species assemblages, in a bid to quantitatively elucidate relationships between offshore infrastructure and marine species.
McLean, DL., Gates, AR., Benfield, MC., Bond, T., Booth, D., Bunce, M., Fowler, AM., Harvey, ES., Macreadie, PI., Rouse, S., Parsons, MJG., Partridge, JC., Pattiaratchi, C., Thomson, PG., Todd, VLGT., and Jones, DOB
Remotely operated vehicles (ROVs) are used extensively by the offshore oil and gas and renewables industries for inspection, maintenance, and repair of their infrastructure. With thousands of subsea structures monitored across the world’s oceans from the shallows to depths greater than 1,000 m, there is a great and underutilized opportunity for their scientific use. Through slight modifications of ROV operations, and by augmenting industry workclass ROVs with a range of scientific equipment, industry can fuel scientific discoveries, contribute to an understanding of the impact of artificial structures in our oceans, and collect biotic and abiotic data to support our understanding of how oceans and marine life are changing. Here, we identify and describe operationally feasible methods to adjust the way in which industry ROVs are operated to enhance the scientific value of data that they collect, without significantly impacting scheduling or adding to deployment costs. These include: rapid marine life survey protocols, imaging improvements, the addition of a range of scientific sensors, and collection of biological samples. By partnering with qualified and experienced research scientists, industry can improve the quality of their ROV-derived data, allowing the data to be analyzed robustly. Small changes by industry now could provide substantial benefits to scientific research in the long-term and improve the quality of scientific data in existence once the structures require decommissioning. Such changes also have the potential to enhance industry’s environmental stewardship by improving their environmental management and facilitating more informed engagement with a range of external stakeholders, including regulators and the public.
Fujii, T., Pondella, D.J., Todd, V.L.G. & Guerin, A.J.
Some of the most productives and biodiverse communities occur on “reefs” (Birkeland, 2015). Many species benefit from physical presence of habitat-forming reefs which provide complex three-dimensional hard substrates and a greater number of ecological niches (Loke et al., 2015). Although reefs are often exemplified by “corals,” they also include other seafloor features such as biogenic substrates, natural bedrock, and man-made sub-sea structures (Steimle and Zetlin, 2000). Installation of sub-sea infrastructure is often considered to have negative impacts on surrounding marine ecosystems (Halpern et al., 2008; Benn et al., 2010; Bullieri and Chapman, 2010), although some studies show that such structures can also have beneficial effects by acting as “artificial reefs” (Gass and Roberts, 2006; Claisse et al., 2014).
Marine ecosystems are changing at alarming rates as a result of increasing anthropogenic influences (Halpern et al., 2008; McCauley et al., 2015; Duarte et al., 2020), and artificial structures are becoming ubiquitous. The sphere of influence, and effects of these artificial habitats on marine ecosystem dynamics, are poorly understood. This Research Topic assembles 11 articles investigating relationships between marine ecosystem dynamics and various types of anthropogenic structures globally. Here we present an overview of these contributions and highlight emerging views and future directions in this field.
Ruffert, M, Todd, VLG. & Todd, IB.
C-PODs are used for Passive Acoustic Monitoring (PAM) of harbour porpoises (Phocoena phocoena) at an offshore open sea location in the German North Sea.
Diel patterns of echolocation click trains are extracted from minimum inter-click interval (minICI) data by binning. The aim of this study is to reassess and refine minICI ranges of click train data with particular consideration to the binning widths. Emphasis is also placed on choosing an appropriate visualisation of these binned data.
Key ecological results include presence of higher train rates during the day with intermediate minICI values defined by the range 6–28 ms and a higher train rate with short minICI values 1.25–2.00 ms at night. This indicates an increase in porpoise feeding behaviour, or change of style, at night. Click trains with long minICI values >35 ms occur at an equal rate throughout both diel phases, suggesting a more routine behaviour, such as navigation.
Results could be revealed only by judicious choice of binning widths, e.g. previously overlooked patterns within historical echolocation data. The classification methodology can be used to analyse echolocation trains from a variety of species and can be applied to any PAM data with the relevant click parameters.
Losada Ros, MT, Al-Enezi, E, Cesarini, E, Canonico, B, Bucci, C, Alves Martins, MV, Papa, S, & Frontalini, F Water, 12(4), 1018 (2020)
Heavy metals are one of the most hazardous pollutants in marine environments because of their bioaccumulation and biomagnification capabilities. Among them, cadmium (Cd) has been considered as one of the most dangerous for marine organisms. Here we incubated Ammonia cf. parkinsoniana specimens, a benthic foraminiferal taxon used in previous experiments, for up to 48 h in natural seawater with different concentrations of Cd to unravel the physiological change. We document a reduced pseudopodial activity of the Cd-treated specimens at concentrations >10–100 ppb in comparison with the control specimens. Moreover, confocal images of Cd-treated specimens using Nile Red as a fluorescent probe reveal an enhanced intracellular neutral lipid accumulation in the form of lipid droplets at 6 h and 12 h. This bioassay experiment allows for the direct evaluation of Cd-dose to A. cf. parkinsoniana-response relationships under laboratory controlled conditions and provides complementary information to field observations as well as to water quality guidelines and thresholds.
Todd, VLG, Williamson, LD., Cox, SE., Todd, IB. & Macreadie, PI.
Offshore Oil & Gas (O&G) infrastructure creates artificial reef complexes that support marine communities in oceans. No studies have characterized the first wave of colonization, which can reveal information about habitat attraction and ecological connectivity. Here we used opportunistically-collected industrial Remotely Operated Vehicles (ROVs) to investigate fish and invertebrate colonization on a new North Sea O&G platform and trenching of an associated pipeline. We observed rapid colonization of fish communities, with increases in species richness (S), abundance (N), and diversity (H′) over the first four days (the entire study period). By contrast, there was minimal change in motile invertebrate communities over the survey period. After trenching, invertebrate S, N and H′ decreased significantly, whilst fish S, N and H′ increased. This study is the first to report on the pioneer wave of fish and invertebrate colonization on O&G infrastructure, thereby providing rare insight into formation of new reef communities in the sea. These short and opportunistic data are valuable in terms of showing what can be discovered from analysis of ‘pre-installation’ ROV footage of O&G structures, of which there are terabytes of data held by O&G companies waiting to be analyzed by environmental scientists.
Lucke, K., Clement, D., Todd, V., Williamson, L., Johnston, O., Floerl, L., Cox, S., Todd, I. & McPherson, C.R.
Document 01725, Version 1.0. Technical report by JASCO Applied Sciences (2019)
Cawthron Institute, and Ocean Science Consulting Ltd. for the Department of Conservation, New Zealand.
The North Island population of Hector’s dolphins (Cephalorhynchus hectori) is formally described as a subspecies, the Māui dolphin (Cephalorhynchus hectori maui). Both Hector’s and Māui dolphins, are endemic to New Zealand waters, where animals are exposed to a range of human (anthropogenic) and non-human-induced threats. To better protect these species, the Department of Conservation (DOC) and Fisheries New Zealand (FNZ) are currently in the process of updating the Threat Management Plan (TMP) for Hector’s and Māui dolphins. To assist in determining potential measures that could be taken to protect these dolphins from non-fishing related threats, DOC commissioned
JASCO Applied Sciences (JASCO) to undertake a literature review on potential impacts of petroleum and minerals exploration and production on Hector’s and Māui dolphins. This document presents a collaborative effort by JASCO, Cawthron Institute (New Zealand) and Ocean Science Consulting NZ (Asia-Pacific) Limited (OSC-NZ).
Williamson, B., Fraser, S., Williamson, L., Nikora, V. & Scott, B.
There is uncertainty on the ecological effects of tidal stream turbines. Concerns include animal collision with turbine blades, disruption of migratory and foraging behaviour, attraction of animals to prey aggregating around turbines, or conversely displacement of animals from preferred habitat.
This study used concurrent ecological and physical measurements to show the predictability of fish school characteristics (presence, school area and height above seabed) in a high energy tidal site across spring/neap, ebb/flood and daily cycles, and how this changed around a turbine structure.
The rate of schools and school area per hour increased by 1.74 and 1.75 times respectively around a turbine structure compared to observations under similar conditions without a turbine structure. The largest schools occurred at peak flow speeds and the vertical distribution of schools over the diel cycle was altered around the turbine structure.
While predictable attraction or aggregation of prey may increase prey availability and predator foraging efficiency, attraction of predators has the potential to increase animal collision risk. Predictable changes from the installation of turbine structures can be used to estimate cumulative effects on predators at a population level. This study can guide a strategic approach to the monitoring and management of turbines and arrays.
Todd, VLG., & Williamson, LD.
Distributions of Daubenton’s bat (Myotis daubentonii), common pipistrelle, (Pipistrellus pipistrellus), and soprano pipistrelle (Pipistrellus pygmaeus) were investigated along and altitudinal gradient of the Lledr River, Conwy, North Wales, and presence assessed in relation to the water surface condition, presence/absence of bank-side trees, and elevation. Ultrasound recordings of bats made on timed transects in summer 1999 were used to quantify habitat usage. All species significantly preferred smooth water sections of the river with trees on either one or both banks; P. pygmaeus also preferred smooth water with no trees. Bats avoided rough and cluttered water areas, as rapids may generate high-frequency echolocation-interfering noise and cluttered areas present obstacles to flight. In lower river regions, detections of bats reflected the proportion of suitable habitat available. At higher elevations, sufficient habitat was available; however, bats were likely restricted due to other factors such as a less predictable food source. This study emphasizes the importance of riparian habitat, bank-side trees, and smooth water as foraging habitat for bats in marginal upland areas until a certain elevation, beyond which bats in these areas likely cease to forage. These small-scale altitudinal differences in habitat selection should be factored in when designing future bat distribution studies and taken into consideration by conservation planners when reviewing habitat requirements of these species in Welsh river valleys, and elsewhere within the United Kingdom.
Todd, VLG., Jiang, J., and Ruffert, R.
The modelled acoustic characteristics of three Acoustic Harassment Devices (AHDs) deployed from a fully operational salmonid fish farm, located in the Sound of Mull, Scotland (UK) are presented, using empirical seabed and water column measurements at the same location. In the Beaufort Sea state 0, the depth range of 10–50 m is the maximum range at which AHDs are potentially audible to five marine mammal species. The species present within this survey region are: the harbour porpoise, Phocoena phocoena (99.1 km), the killer whale, Orcinus orca (110 km), the bottlenose dolphin, Tursiops truncatus (89.6 km), the common seal, Phoca vitulina (88 km), and the grey seal, Halichoerus grypus (69 km). Consequently, within the Sound of Mull, all three AHDs could be heard throughout the water column by all species. For two models of AHDs, a behavioural disturbance level of between 140 dB–180 dB is observed at 1.3 km. Habitat displacement is a cause for concern, particularly if several fish farms within a small area all deploy AHDs simultaneously. This can create a confusing sound field of varying intensity, which has potential to deter harbour porpoises from sections of their habitat.
If positioned effectively, AHDs have the potential to deter all five marine mammal species from industrial operations such as aquaculture facilities. Source levels, propagation and transmission loss measurements were highly variable and should be considered as site specific, meaning new estimates should be made for each situation.
Fowler, AM, Jørgensen, A-M, Svendsen, JC, Macreadie, PI, Jones, DO, Boon, AR, Booth, DJ, Brabant, R, Callahan, E, Claisse, JT, Dahlgren, TG, Degraer, S, Dokken, QR, Gill, AB, Johns, DG, Leewis, RJ, Lindeboom, HJ, Linden, O, May, R, Murk, AJ, Ottersen, G, Schroeder, DM, Shastri, SM, Teilmann, J, Todd, VLG, Van Hoey, G, Vanaverbeke, J, & Coolen, JW.
The removal of thousands of structures associated with oil and gas development from the world’s oceans is well underway, yet the environmental impacts of this decommissioning practice remain unknown. Similar impacts will be associated with the eventual removal of offshore wind turbines. We conducted a global survey of environmental experts to guide best decommissioning practices in the North Sea, a region with a substantial removal burden. In contrast to current regulations, 94.7% of experts (36 out of 38) agreed that a more flexible case-by-case approach to decommissioning could benefit the North Sea environment. Partial removal options were considered to deliver better environmental outcomes than complete removal for platforms, but both approaches were equally supported for wind turbines. Key considerations identified for decommissioning were biodiversity enhancement, provision of reef habitat, and protection from bottom trawling, all of which are negatively affected by complete removal. We provide recommendations to guide the revision of offshore decommissioning policy, including a temporary suspension of obligatory removal.
Todd, VLG, Lavallin, EW & Macreadie, PI.
Decommissioning of offshore infrastructure has become a major issue facing the global offshore energy industry. In the North Sea alone, the decommissioning liability is estimated at £40 billion by 2040. Current international policy requires removal of offshore infrastructure when their production life ends; however, this policy is being questioned as emerging data reveal the importance of these structures to fish and invertebrate populations. Indeed, some governments are developing ‘rigs-to-reef’ (RTR) policies in situations where offshore infrastructure is demonstrated to have important environmental benefits. Using Remotely Operated Vehicles (ROVs), this study quantified and analysed fish and invertebrate assemblage dynamics associated with an oil and gas (O&G) complex in the Dogger Bank Special Area of Conservation (SAC), in the North Sea, Germany. We found clear depth zonation of organisms: infralittoral communities (0–15 m), circalittoral assemblages (15–45 m) and epi-benthic communities (45–50 m), which implies that ‘topping’ or ‘toppling’ decommissioning strategies could eliminate communities that are unique to the upper zones. Sessile invertebrate assemblages were significantly different between structures, which appeared to be driven by both biotic and abiotic mechanisms. The O&G complex accommodated diverse and abundant motile invertebrate and fish assemblages within which the whelk Buccinium undatum, cod fish Gadus morhua and lumpsucker fish Cyclopterus lumpus used the infrastructure for different stages of reproduction. This observation of breeding implies that the structures may be producing more fish and invertebrates, as opposed to simply acting as sites of attraction (sensu the ‘attraction vs production’ debate). At present, there are no records of C. lumpus spawning at such depth and distance from the coast, and this is the first published evidence of this species using an offshore structure as a spawning site. Overall, this study provides important new insight into the role of offshore O&G structures as habitat for fish and invertebrates in the North Sea, thereby helping to inform decommissioning decisions.
Todd, V.L.G. & Waters, D.A.
Distribution and abundance of two temperate-zone insectivorous bats, Daubenton’s (Myotis daubentonii) and common pipistrelle (Pipistrellus pipistrellus), and their potential prey were studied along an altitudinal river gradient in relation to environmental variables including air temperature, wind speed, water surface state, and presence or absence of bank-side trees. Using a Latin square design at ten different habitat combination types, ultrasound recordings and insect sampling were carried out to quantify bat habitat preferences and potential prey abundance and classification. Myotis daubentonii and P. pipistrellus activity was significantly higher over smooth water river sections with trees on either or both banks while cluttered and rapid water sections were avoided. Conversely, insect abundance was not related to water surface condition or the presence or absence of bank-side trees. Nematoceran dipterans made up 98% of insect numbers, with small numbers of brachycerans and cyclorrhaphans. The most common insect families were Chironomidae and Ceratopogonidae. There was no correlation between bat activity and aerial insect activity, suggesting that aerial prey availability is not the sole driver of bat habitat choice. Bat and insect abundance were each correlated positively with night-time air temperature. No bat passes or flying insects were recorded at temperatures < 4°C. At 5°C, only M. daubentonii were observed foraging, and at 6ºC there were more M. daubentonii present than any other bat species. No correlation was found between number of bat passes hr-1 and wind speed, moon visibility, moon phase, and percentage cloud cover. Rain did not affect M. daubentonii, but P. pipistrellus preferred to forage on dry nights. Bats were predicted to forage preferentially where aerial insect abundance was highest but this was found to not be case, and other aspects such as detection of prey against clutter may have an important role to play in habitat choice.
Ford, B., Jiang, J., Todd, V. & Todd, I.
24th International Congress on Sound and Vibration. London, UK (2017)
Offshore pile and conductor driving can potentially cause acoustic disturbance to marine mammals, such as cetaceans (whales, dolphins and porpoises), the odontocetes (toothed cetaceans) of which are particularly reliant on the underwater sound field for spatial orientation, navigation, prey capture, communication, and predator avoidance. Disturbance ranges from behavioural changes, masking of communication signals, and temporary or even permanent hearing loss. There is currently no specific legal noise threshold in UK waters, but the Marine Management Organisation (MMO) has stipulated the requirement for noise monitoring during pile-driving operations when some windfarms are constructed. Measurements presented in this paper were taken during nearshore pile driving in the UK from a support vessel located 750 m from each pile (wind-turbine foundation). Results were compared with a threshold issued by the German Federal Environment Agency (UBA). Noise levels beyond the measurement location were predicted using a numerical model. Comparing results with the Southall criteria (Southall, B. L., et al., Marine Mammal Noise Exposure Criteria: Initial Scientific Recommendations, Aquatic Mammals, 33 (4), 2007), the Joint Nature Conservation Committee (JNCC) 500 m exclusion zone offered protection for most of marine mammals during pile driving events in this particular case.
The illustrious marine scientist and explorer, Sylvia Earle, once said of anthropogenic (man-made) noise: ‘Undersea noise pollution is like the death of a thousand cuts. Each sound in itself may not be a matter of critical concern, but taken all together, noise from shipping, seismic surveys, and military activity is creating a totally different environment than existed even 50 years ago. That high level of noise is bound to have a hard, sweeping impact on life in the sea’. The subtle, but key phrase in that quote is ‘bound to’. There is negligible doubt that some noise activities are detrimental to marine mammals (and, in some cases, will cause death), but quantifying this doubt is hard.
Todd, V.L.G., Gardiner, J. C., & Todd, I. B.
A decade of visual and acoustic detections of marine megafauna around offshore Oil & Gas (O&G) installations in the North and Irish Seas are presented. Marine megafauna activity was monitored visually and acoustically by Joint Nature Conservation Committee (JNCC) qualified and experienced Marine Mammal Observers (MMO) and Passive Acoustic Monitoring (PAM) Operators respectively, ith real-time towed PAM in combination with industry standard software, PAMGuard. Monitoring was performed during routine O&G industrial operations for underwater noise mitigation purposes, and to ensure adherence to regulatory guidelines. Incidental sightings by off-effort MMOs and installation crew were also reported. Visual and acoustic monitoring spanned 55 non-consecutive days between 2004 and 2014. A total of 47 marine mammal sightings were recorded by MMOs on dedicated watch, and 10 incidental sightings of marine megafauna were reported over 10 years. Species included: harbour porpoise (Phocoena phocoena), Atlantic white-sided dolphin (Lagenorhynchus acutus), white beaked dolphin (Lagenorhynchus albirostris), common dolphin (Delphinus delphis), minke whale (Balaenoptera acutorostrata), common seal (Phoca vitulina), grey seal (Halichoerus grypus) and, basking shark (Cetorhinus maximus). Passive Acoustic Monitoring was conducted on two occasions in 2014; 160 PAM hours over 12 days recorded a total of 308 individual clicks identified as harbour porpoises. These appear to be the first such acoustic detections obtained from a North Sea drilling rig whilst using a typically configured hydrophone array designed for towing in combination with real-time PAMGuard software. This study provides evidence that marine megafauna are present around mobile and stationary offshore O&G installations during routine operational activities. On this basis, Environmental Impact Assessments (EIAs) for decommissioning O&G platforms should be carried-out on a case-by-case basis, and must include provisions for hitherto overlooked marine megafauna.
Jiang J., Todd V.L.G., Gardiner J.C., & Todd I.B.
In: Euronoise 2015, p. 6. Acoustical Society of the Netherlands (NAG) and Belgian Acoustical Society (ABAV), Maastricht, The Netherlands (2015)
Cetaceans (whales, dolphins and porpoises) rely heavily on sound for communication, foraging, predator avoidance, orientation, and navigation. Noise generated by offshore construction work, such as piling during wind-farm construction and conductor hammering during exploration-drilling operations, has the potential to cause behavioural changes, masking of communication signals or, in extreme cases, a temporary loss of hearing in marine mammals. Numerous countries have issued individual standards for offshore noise monitoring before, during and after construction, but few standards specify actual noise thresholds, due to the complexity of underwater environments. Underwater noise measurements were taken from an offshore support vessel, stationed at distances of 750 m, 1 km, and 2 km away from a drilling-rig conductor hammering site in the North Sea. Results were then compared with the only official threshold value, which was issued by the German Federal Environment Agency (UBA). Sound Pressure Level (SPL) at various measurement locations, and beyond was predicted. The Sound Exposure Level for conductor hammering noise was monitored in real time, and did not reach 160 dB re 1 μPa at a distance of 750 m, in accordance with the UBA. Given the known behaviour of porpoises around offshore installations, it is unlikely that animals were exposed to levels of sound that might be potentially detrimental in the single and brief 2 h period that conductor hammering occurred.
Todd, V.L.G., Gardiner, J.C., & Todd, I.B.
Decommissioning of Offshore and Subsea Structures, Glasgow, UK: ASRANET pp. 10 (2015)
Condensed highlights from a decade of Marine Mammal Observer (MMO) and Passive Acoustic Monitoring (PAM) projects carried out from stationary and on-tow Oil & Gas (O&G) exploration jack-up drilling-rigs and production platforms is presented. The majority of work was undertaken as routine monitoring and mitigation permit requirements, but a partial aim was to investigate the hypothesis that, because of a potential rig-as-a-reef effect, echolocation activity of harbour porpoises (Phocoena phocoena) is likely to be higher at offshore installations compared with the open sea. Porpoise activity was monitored visually and acoustically using MMOs, real-time PAM, and a brief, controlled experiment using T-PODs – autonomous, static, echolocation-click detectors. Throughout the last decade, porpoises were detected visually, acoustically, and consistently at varying levels, at all offshore locations undergoing routine operational activities. The controlled T-POD experiment gave reasonable evidence to support the hypothesis that porpoises may target offshore installations compared to the open sea, but further long-term, replicated and controlled visual and acoustic experiments using recently optimised mooring techniques are required to ‘put the theory to bed’. In conclusion, this paper puts forward the notion that decommissioning of O&G installations in the North Sea may remove valuable porpoise foraging habitat and thus may have implications for the long-term survival of this listed and threatened species.
Todd, V.L.G., Todd, I.B., Gardiner, J.C., & Morrin, E.C.N.
Marine Mammal Observer and Passive Acoustic Monitoring Handbook is the ultimate instruction manual for mitigation measures to minimise man-made acoustical and physical disturbances to marine mammals from industrial and defence activities.
Based on more than two decades of offshore experience, and a decade of supplying MMO and PAM services (commercial and scientific), the Handbook is a long overdue reference guide that seeks to improve standards worldwide for marine operations such as seismic and drilling exploration, wind farm piling, civil engineering, dredging, rock-dumping, and hydrographical surveys. By popular request, this manual will also form an accompaniment to MMO and PAM courses.
The Handbook consolidates all aspects of this discipline into one easily accessible resource, to educate all stakeholders (e.g. MMOs, PAM operators, suppliers, recruitment agencies, clients, contractors, regulators, NGOs, consultants, scientists, academia and media), regardless of experience.
Topics include worldwide legislation, compliance, anthropogenic noise sources and potential effects, training, offshore life, visual and acoustic monitoring (theory and practice), marine mammal distribution, hearing and vocalisations, and report writing.
Advice is provided on implementing sensible and practical mitigation techniques, appropriate technologies, data collection, client and regulator liaison, and project kick-off meetings.
A foreword is provided by Dr Phillip J. Clapham.
Todd, V.L.G., Todd, I.B., Gardiner, J.C., Morrin, E.C.N., MacPherson, N.A., DiMarzio, N.A., & Thomsen, F.
Marine dredging is an excavation activity carried out worldwide by many industries. Concern about the impact dredging has on marine life, including marine mammals (cetaceans, pinnipeds, and sirenians) exists, but effects are largely unknown. Through consulting available literature, this review aims to expand on existing knowledge of the direct and indirect, negative and positive impacts on marine mammals. In terms of direct effects, collisions are possible, but unlikely, given the slow speed of dredgers. Noise emitted is broadband, with most energy below 1 kHz and unlikely to cause damage to marine mammal auditory systems, but masking and behavioural changes are possible. Sediment plumes are generally localized, and marine mammals reside often in turbid waters, so significant impacts from turbidity are improbable. Entrainment, habitat degradation, noise, contaminant remobilization, suspended sediments, and sedimentation can affect benthic, epibenthic, and infaunal communities, which may impact marine mammals indirectly through changes to prey. Eggs and larvae are at highest risk from entrainment, so dredging in spawning areas can be detrimental, but effects are minimized through the use of environmental windows. Sensitive environments such as seagrass beds are at risk from smothering, removal, or damage, but careful planning can reduce degradation. Assessing impacts of contaminant remobilization is difficult, but as long as contaminated sediments are disposed of correctly, remobilization is limited in space and time. Effects of suspended sediments and sedimentation are species-specific, but invertebrates, eggs, and larvae are most vulnerable. Positive effects, including an increase in food, result from greater nutrient loads, but are often short term. Dredging has the potential to impact marine mammals, but effects are species and location-specific, varying also with dredging equipment type. In general, evidence suggests that if management procedures are implemented, effects are most likely to be masking and short-term behavioural alterations and changes to prey availability.
Marine Scientist 43, 22025 (2013)
Whether ‘tis nobler in the mind to suffer the slings and arrows of outrageous fortunes, or to take arms against a sea of troubles. The dilemma Hamlet faced in the 1600s is strikingly similar to the one faced today by oil and gas companies, regulators, policy-makers and Non-Governmental Organisations (NGOs) when it comes to decommissioning offshore oil and gas installations at the end of their operational lifetimes. There is no doubt that the ‘outrageous fortune’ generated by oil and gas firms sustains the economy, drives industry and fuels technological progress, but what happens after reserves are spent and the ‘sea of troubles’ manifest themselves potentially as environmental consequences thereafter?
Todd, V.L.G., & Morrin, E.C.N
Irish Birds 9, 638-639 (2013)
On 7 May 2012 a second-year Ring-billed Gull Larus
delawarensis was observed in flight near the south western
limit of the Celtic Sea at 48° 27’N 09° 11’W at 14.07 GMT(about 330 km south of Ireland). This gull was encountered only once during afive-day offshore cetacean survey between 6 and 10 May 2012. Throughout the monitoring period, two observers were on watch for a combined total of 130 hours. The Ring-billed Gull approached to 5 m and followed the vessel for a period of about two minutes before heading out to sea. The gull was accompanied by Gannets Morus bassanus, which were the only other bird species seen circling and following the vessel regularly.
Ruffert, M., Todd, I.B., Todd, V.L.G., & Gardiner, J.C.
In: Proceedings of 11th European Conference on Underwater Acoustics (ECUA) (eds. By Popper, A., & Hawkins, A.) Institute of Acoustics, 2-6 July, Edinburgh (2012)
International Journal of Ocean Systems (2011)
Rigs may provide vital habitat for endangered marine mammals and their prey Scientists from Scotland-based Ocean Science Consulting (OSC) were the first in the world to eavesdrop on the acoustic activity of marine mammals around the legs of North Sea offshore oil and gas installations. From 2004 to 2010, OSC used autonomous underwater echolocation click-detectors called T-PODs and C-PODs to monitor acoustic activity of harbour porpoises (Phocoena phocoena) around oil and gas installations in the German sector of the North Sea. Under the supervision of Dr Victoria Todd and Ian Todd, OSC initially assessed the underwater noise regime of rigs, to determine if drilling and operational sounds were likely to be audible to porpoises. The next stage of the research was to find out if porpoises were present around rigs, and to what extent.
Todd, V.L.G., & Grove, J.S.
Journal of the Marine Biological Association – Global Marine Environment (2011)
In 1995, a complete survey of the fish collection in the Charles Darwin Research Station (CDRS) Museum (Galápagos Islands, Ecuador) was undertaken. Five specimens represented possible new records to the archipelago, but insufficient material was available at CDRS to confirm identification.
Science World 67 8-12 (2010)
Last April 20, an explosion rocked the Deepwater Horizon oil-drilling rig – a platform the size of two football fields moored in the Gulf of Mexico. The rig, operated by energy giant BP, had just placed a temporary seal on the oil well it was drilling. A more permanent production platform was planned to extract the 50 million barrels of oil in the reservoir that workers had tapped 5,486 meters (18,000 feet) below the seafloor. One barrel equals 159 liters (42 gallons). But two days after the explosion, the fiery rig sank a mile to the bottom of the Gulf. Near the wreckage, broken pipes steadily leaked an estimated 35,000 to 60,000 barrels of oil per day from the underwater well.
Todd, V.L.G., & Grove, J.S.,
In 1995, a complete survey of the fish collection in the Charles Darwin Research Station (CDRS) Museum (Gala´pagos Islands, Ecuador) was undertaken. Five specimens represented possible new records to the archipelago, but insufficient material was available at CDRS to confirm identification. On 5 November 2007, the specimens were removed from the CDRS fish collection under licence from the Parque Nacional Gala´pagos (PNG) on loan to the Los Angeles County Museum of Natural History (LACM). Identification of all species was confirmed using comparative LACM voucher specimens, including X-rays, scientific keys and other resources, which were, at the time, unavailable to scientists at the CDRS. Four of the five specimens were incorrectly identified in 1995, the fifth, the golden trevally, Gnathodon speciosus, is the first confirmed record of this species for the Gala´pagos. One of the originally mis-identified specimens, the longnose anchovy (Anchoa nasus), proved to be A. ischana
(sharpnose anchovy), and A. nasus can now be eliminated as a verified record from the islands. The first confirmed record of the sharp-tail mola, Masturus lanceolatus, for the archipelago is also presented based on photographic and video evidence. The first physical evidence of the white shark, Carcharodon carcharias, in the Gala´pagos Archipelago based on discovery of a tooth and C14 analysis, is presented.
Todd, V.L.G., & White, P.R.
2nd International Conference on the Effects of Noise on Aquatic Marine Life (2010)
Underwater sound recordings were made from the Noble Kolskaya jack-up gas-exploration drilling-rig in the German region of the Dogger Bank, North Sea. The aim was to document received levels, characteristics, and range-dependence of sounds produced by the rig’s site installation and drilling during the winter. Sound pressure levels (SPLs) generated by the Kolskaya were similar to previous measurements from the metal-legged bottom-founded rigs, both in level (120 dB re 1μPa) and in frequency range of dormant tonals (2-1400 Hz). Received levels were highly variable over short periods and generally varied by 15-20 dB between quietest (holding) and loudest (drilling) operations. The rig was significantly quieter than its associated support vessels at low frequencies, though radiated noise levels were higher above 2 kHz. The rig’s high-frequency SPLs dropped rapidly above 8 kHz.
British Wildlife Magazine 27 40 (2009)
The last report was dominated by the ‘big’ news of Blue Whales Balaenoptera musculus and ‘singing’ Humpback Whales Megaptera novaeangliae off Ireland. It was very opportune timing then for the Bioacoustics Research Program at Cornell University, in the United States, to publish some preliminary results (Technical Report 08-07) from a ten-year period (1996-2005) of monitoring seabed-mounted hydrophone arrays operated by the US Navy as part of the SOund SUrveillance System (SOSUS). The system was designed to detect submarine activity at low frequencies and is also, coincidentally, ideal for listening for and tracking the loud, infrasonic calls of large baleen whales, often at ranges of several hundred kilometres.
BBC Wildlife Magazine 27 40 (2009)
Greenpeace may oppose it, but a programme of sinking old oil rigs would interest porpoises. The question of whether oil and gas rigs can benefit marine life has been reopened after a study suggested that the structures can create extensive ecosystems and that, in UK waters, porpoises in particular now associate them with food sources.
Mammal News 155 10-11 (2009)
Let’s face it, when it comes to environmental stewardship, oil and gas companies get a bad press. The media have successfully portrayed the worst aspects of this industry, notably graphic representations of wrecked oil tankers, flailing in raging surf and brown foam, against a backdrop of glistening black shores with heart-wrenching images of oil-drenched birds and lifeless sea otters. As a result of these connotations, a recently discovered and potentially significant environmental benefit of the oil and gas industry could prove controversial.
Todd, V.L.G., Todd, I.B., & Treganza, N.C.
Echolocation clicks of harbour porpoises (Phocoena phocoena) were detected with T-PODs, autonomous, passive, acoustic-monitoring devices, deployed from an offshore-exploration-drilling-rig and gas-production-platform complex in the Dogger Bank region of the North Sea from 2005 to 2006. Echolocation-click trains were categorized into four phases of the diel cycle: morning, day, evening, and night. Porpoises were present near (,200 m) the platform, and there was a pronounced diel pattern in echolocation activity; the number of porpoise encounters (visits) was greater by night than by day. The number of click trains with a minimum interclick interval of ,10 ms also increased at night. This was confirmed by a comparison of the ratios of feeding buzzes to searchphase clicks (feeding buzz ratios) and an analysis of the changes in pulse-repetition frequencies within each train. A reasonable interpretation of this pattern was that porpoises were feeding below or around the platform at night. The evidence for changes in activity during the morning and evening was less clear, so these may be transitional phases. The pattern of porpoise-echolocation behaviour around this platform is related most probably to the diel activity of their prey. If porpoises cluster regularly around such installations within 500-m shipping exclusion zones, they may be omitted from population surveys. We conclude that offshore installations may play an important role as nocturnal porpoise-feeding stations in an overfished environment, but that further replicated and controlled studies are required. These findings should be taken into consideration during offshore-installation-decommissioning decisions in the North Sea
Todd, V.L.G., Todd, I.B., Lepper, P.A., & Treganza, N.C.
Fifth International Conference of Bio-Acoustics 8 31 March – 2 April Holywell Park, Loughborough University, UK (2009)
Harbour porpoises (Phocoena p. phocoena L.) are vocal animals and their activity can be monitored effectively using underwater, autonomous, passive-acoustic cetacean-click detectors called T-PODS [e.g. 1, 2, 3]. The characteristics of porpoise-echolocation clicks have been described in great depth over the last forty years [4-10]; clicks can be emitted singularly or in groups known as ‘trains’. There is a linear correlation between porpoise-echolocation pulse intervals and target range [11, 12] with a peak in repetition rate as the animal nears the target, analogous to the ‘terminal buzzes’ repeatedly observed in echolocating bats . Determination of a successful prey-capture event in wild echolocating bats has been achieved effectively [e.g.14], but for wild porpoises, underwater filming of prey-capture attempts is extremely troublesome. Moreover, in the wild, without visual confirmation, any correlation between porpoise buzz activity and feeding success cannot be assumed a priori without experimental evidence, because a high buzz rate may simply be associated with increased foraging effort for the same amount of prey. Nonetheless, it is conceivable that by using acoustics alone, a proxy of feeding activity could be surmised by examining the relative incidence of increasing click rates, emitted during range-locking echolocation behaviour, and the associated decreasing interval between clicks, known as ‘inter-click-intervals (ICI)’ [see 2]. While we cannot exclude the possibility that a decrease in ICI could be associated with inanimate object investigation, such as the rig structures, a link between feeding a decreasing ICI has been established for foraging Blainville’s beaked whales (Mesoplodon densirostris)  and harbour porpoises .
Gordon, J., Thompson, D. Gillespie, D., Lonegran, M., Calderan, S., Jaffey, B., & Todd, V.L.G.
International Meeting on Marine RenewableEnergy and the Environment (MAREE) 16-17 June Royal Institution, London, UK (2008)
The construction of offshore wind-farms generates a range of high-level underwater noise to which marine mammals, which have acute underwater hearing and use acoustics as their primary sensory modality, is at levels that could cause hearing or physical damage. Risks will rise as pile diameter increases. We explore the risks posed by pile driving to the hearing of marine mammals found in the vicinity of the UK offshore wind farms using a cumulative exposure model incorporation animal movement and simple propagation models. Runs of these models showed that marine mammals’ hearing could be affected at ranges of several kms and highlight animal movement and sound propagation as poorly measured parameters with a major influence on the risk of damage.
Todd, V.L.G., & Waters, D.A.,
Foraging in Daubenton’s bats Myotis daubentonii, at two altitudinal locations along a river gradient in North Wales was investigated in relation to aerial insect density and to the density of prey on the water surface. Prey capture in Daubenton’s bats consisted of aerial hawking, where prey was taken in the air, and trawling, where bats gaffed invertebrates from the water surface. Aerial hawking accounted for 86% of all prey capture attempts, despite aerial insect availability falling close to zero for much of the night. Conversely, prey density on the water surface was an order of magnitude higher than aerial prey density and increased through the night due to aquatic invertebrate drift. At the higher altitude site, M. daubentonii switched prey capture strategy to gaffing, possibly to reflect this change in prey availability on the water’s surface, but at the lower altitude site, they maintained aerial hawking as the preferred strategy. The switch to gaffing may be inhibited by the significant downstream accumulation of large numbers of inedible exuviae of caddis flies, Trichoptera, at the low-altitude site, which form both acoustic clutter and increase the probability of capturing inedible prey, making foraging less efficient. These small altitudinal differences in foraging strategy should be factored into the design of future altitudinal bat foraging studies and if found to be a widespread strategy, taken into consideration by conservation planners when reviewing the habitat requirements of Daubenton’s bats in river valleys within the United Kingdom.
Todd, V.L.G., Lepper, P.A., & Todd, I.B.,
In: Improving Environmental Performance: A Challenge for the Oil 60pp. Industry Proceedings of the International Association of Drilling Contractors
3-4 April Amsterdam, the Netherlands (2007)
Two sets of field trials were performed from offshore installations in the German Entenschnabel sector of the Dogger Bank, North Sea. Trial 1 was undertaken from the jackup drilling rig Noble Kolskaya and its support vessel Northern Seeker, at locations B4-5 and B11-4 over three discrete periods (October/November 2004 and December 2004/January 2005). The purpose of these trials was to perform measurements of acoustic noise levels generated by the rig during routine activities and to undertake preliminary passive acoustic monitoring (using T-PODs) of porpoises (Cetacea: Phocoena phocoena) around the rig. Trial 2 was a six-month study (August 2005-January 2006) using T-PODS around the A6-A gas-production platform when it was isolated, when the Noble Kolskaya was docked alongside, and after the rig’s departure.
Gordon, J., Gillespie, D., Lonergan, M., Calderan, S., Jaffey, B., & Todd, V.L.G.
A report commissioned by COWRIE Ltd, SMRU Ltd, 7 Woodburn Place, KY16 8LA, St Andrews, Fife, UK (2007)
A number of anthropogenic activities that occur in coastal and offshore waters generate sound or impulses at levels which are sufficiently high to pose a risk of causing physical damage or hearing impairment in sensitive wildlife such as marine mammals. The use of explosives, for example, for well-head removal, certainly poses this risk and it is possible that pile driving during windfarm construction could also do so. One potential means of reducing the risk of damage to marine mammals from such activities is to move sensitive animals out of the high risk area by using aversive or alarming sounds produced by an acoustic mitigation device (AMD). This report investigates the potential for using AMDs for mitigation during windfarm construction, explores the types of acoustic signals that might be suitable for this application, and the devices available for producing them in the field. It makes recommendations in relation to the areas of research that would be needed to develop and quantify the performance of a working system, and reviews legal aspects of using AMDs for mitigation in UK waters.
New Scientist 2581 25 (2006)
Your report on the Galápagos was mostly negative about the impact of tourism on the wildlife of this exceptional archipelago (14 October, p8). In 1995, I spent six months on the islands working as a volunteer research scientist.
Lepper, P.A., Turner, V.L.G., Goodson, A.D., & Black, K.D.
Proceedings of the Seventh European Conference on Underwater Acoustics 5-8 July
ECUA, Delft, The Netherlands (2004)
Marine finfish aquaculture fish farm facilities can suffer severe predation from seals and other animals. Underwater transmitting commercial aquaculture acoustic devices (CAADs), intended to provide protection by deterring the close approach of seals are used in many countries. Few reliable acoustic data are available with which to assess the impact of such systems on target and non-target species in the surrounding marine environment. This paper reports an April 2003 study in which 160 kHz bandwidth measurements of source level and power spectra were carried out of three CAAD devices that are currently used in British salmonid fish farm facilities. The three devices tested employed very different signalling methods and whilst the fundamental acoustic frequencies (including harmonics) appear similar, the total energy distribution, delivered into the water column differed considerably.
Turner, V.L.G., Lynch, S.M., Paterson, L., Léon-Cortés, J.L., & Thorpe, J.P.
Marine Ecology Progress Series 247 85-92 (2003)
ABSTRACT: The beadlet sea anemone Actinia equina (L.) shows a well-documented sequence of aggressive responses towards conspecific individuals. Aggression is also shown towards sea anemones of certain other species. A study was carried out to assess aggressive responses of A. equina to other anemones over a wide range of levels of genetic divergence from genetically identical individuals (clonemates) to various other species, all of which were potentially sympatric. The other species used were the dahlia anemone Urticina felina (L.), the gem anemone Bunodactis verrucosa (Pennant), the snakelocks anemone Anemonia viridis (Forskål), the plumose anemone Metridium senile (L.) and the strawberry anemone Actinia fragacea Tugwell. Intraspecific aggression was also studied in A. fragacea. A. equina exhibited high levels of aggression to all the other species and to unrelated (i.e. non-clonal) individuals of its own species, but was never aggressive to clonemates. The levels of aggression shown by A. equina were found to correlate with the genetic divergence of the other anemone. It was also noted that A. equina only left damaging acrorhagial peels on conspecific individuals, whereas A. fragacea never left a peel on other A. fragacea, but produced peels during all successful ‘fights’ against A. equina. It is suggested that the non-self recognition system, which triggers the acrorhagial application behaviour in A. equina, is not species-specific, although the occurrence of acrorhagial peeling may be species-specific.
Ph.D. Thesis (Ecology & Acoustics) p. 250
Department of Biology, University of Leeds, Leeds, UK (2002)
Turner, V.L.G., Waters, D.A., Altringham, J., & Warren, R.
In Z. Akbar (Ed.): 12th International Bat Research Conference 6-8 August
Universuty Kebangsaan, Bangi, Malaysia (2001)
The small, (6-12g) Daubenton’s bat has a wide distribution ranging throughout the Palaearctic over the whole of Europe, Russia, Central Asia and outer India. Individuals feed almost exclusively over water, usually in the 0.3 1.0 m airspace above the water by either aerial hawking insects from the air or gaffing prey from the surface using their large feet or tail membranes (Fig.1.).
Mammalaction News 94 5-6 (2001)
What are killer whales? Whales are dolphins belong to the order Cetacea. There are two sub-orders of whales: Mysticeti (baleen whales, such as the blue whale) and the Odontoceti (the toothed whales, including, for example, the beluga whale). The killer whale, or ‘orca’ (Orcinus orca), belongs to the family: Delphinidae which includes the commonly recognised bottlenose dolphin.
National Trust Conservation Newsletter 6 (1) 7-8 (2001)
Recent work on Daubenton’s bats in Upper Wharfedale funded by The National Trust and The Environment Agency has revealed an unusual population structure. There appears to be a marked sexual segregation, with females occupying the lower reaches of the river, while the upper reaches are populated exclusively by males. Daubenton’s bat is heavily reliant on river systems for foraging and the question is why females do not use the upper reaches, since as male density is high, prey is expected to be abundant? The hypothesis is that the mean prey abundance at higher altitudes is the same as that at lower alititudes, but that due to more marked temperature variations, prey are temporally clustered. Males, which can use torpor (a form of temporary hibernation) during periods of low prey availability, can exploit this resource, while pregnant, or lactating females are effectively excluded since the use of torpor would slow foetus or offspring development.
Hamer, KC & Turner, VLG
The Island Naturalist 33: 3–5 (1997)
The immediate effects of marine oil spills on seabirds in the vicinity of the spill are well known, and large-scale mortality resulting from fouling of plumage and ingestion of oil have been well documented. However in addition to acute lethal effects, populations may experience longer-term sublethal effects of ingested hydrocarbons. These have potentially profound consequences for productivity and population dynamics, but there are very few data to allow a proper assessment of the likely impacts of these factors on different species.
BBC Wildlife Magazine 12: (11) (1994)
Report to the Gesellschaft zum Schutz der Meeresäugetiere (1994)
Report to United Nations Environment Programme, Conservation of Migratory Species (UNEP/CMS) Internal Report (1994)
B.S.c. (Hons) Thesis (Marine biology). Department of Evolution and Environmental Biology, Port Erin Marine Laboratory (University of Liverpool), Port Erin, the Isle of Man, UK, p.125 (1994)