The effect of man-man structures on the marine ecosystem is likely to depend on the type and status of the structure. Commissioning and decommissioning of structures can cause disturbance and displacement of marine mammals. Established structures may also result in displacement due to operational noise, presence of maintenance vessels or habitat destruction. However, such structures may provide refuge for predators or their prey due to access and fishing restrictions within their vicinity. Furthermore, such structures can host artificial reefs and may present foraging opportunities for some predators, for example in a recent paper (Russell et al., 2014) the applicants demonstrated that some seals use such structures for foraging. How either deterrence or attraction to these structures may affect the marine environment is still poorly understood.
We will map the distributions of top predators in the North Sea, including seabirds, seals and cetaceans, and quantify overlap with man-made structures. We will examine how the distributions of apex predators are influenced by proximity to man-made structures, while considering other temporal and spatial variation in their environment (e.g. habitat, depth, temperature). This will provide information on the current effect of man-made structures on the distribution of key apex predators and also on the proportion of the population of each species which could be potentially impacted by disturbance resulting from commissioning and decommissioning.
For finer spatial scale analyses, we will use data from animal-borne devices which record and transmit locational and in some cases behavioural data on harbour and grey seals (minimum sample size of 282) and five species of seabird (n=700). These data will allow us to quantify the encounter rate with man-made structures and also the proportion of encounters that result in the use of structures for foraging. We will investigate how the results vary among individuals, species, structure type and age. Along with the overlap between species and man-made structures, this will allow us to report on the extent to which manmade structures may influence foraging behaviour at a population level. Our results will inform the review of OSPAR Decision 98/3 and any commissioning and decommissioning processes to reduce any negative impact on the ecosystem.