A Ship Traffic Disturbance Vulnerability Index for Northwest European Seabirds as a Tool for Marine Spatial Planning

Abstract

Ship traffic in Northwestern European seas is intense and continuing to increase, posing a threat to vulnerable seabird species as a result of disturbance. However, information on species-specific effects of ship traffic on seabirds at sea is limited, and tools are needed to prioritize species and areas to support the integration of conservation needs in Marine Spatial Planning. In this study, we investigated the responses of 26 characteristic seabird species in the German North and Baltic Seas to experimental ship disturbance using large datasets collected as part of the Seabirds at Sea counts. We developed a Disturbance Vulnerability Index (DVI) for ship traffic combining indicators for species' shyness, escape costs, and compensatory potential, and analyzed the relationships among shyness, escape costs, and vulnerability. The DVI was calculated using the following eight indicators: escape distance, proportion of escaping birds, proportion of birds swimming prior to disturbance, wing loading, habitat use flexibility, biogeographic population size, adult survival rate, European threat and conservation status. Speciesspecific disturbance responses differed considerably, with common scoters (Melanitta nigra) and red-throated loons (Gavia stellata) showing the longest escape distances and highest proportions of escaping individuals. Red-throated loon, black guillemot (Cepphus grylle), Arctic loon (Gavia arctica), velvet scoter (Melanitta fusca), and redbreasted merganser (Mergus serrator) had the highest DVI values, and gulls and terns had the lowest. Contrary to theoretical considerations, shyness correlated positively with escape costs, with the shyest species also being the most vulnerable among the species studied. The strong reactions of several species to disturbance by ships suggest the need for areas with little or no disturbance in some marine protected areas, to act as a refuge for vulnerable species. This DVI can be used in combination with distribution data to identify the areas most vulnerable to disturbance.

Boat disturbance effects on moulting common eiders Somateria mollissima

“…Besides wind direction-in combination with wind speed-this would also involve the transmission of noise under water. Due to the physical properties of water, sound travels much faster and further under water than through air (even under tailwinds) (Everest and Pohlmann 2009). Thus, eider ducks might notice the presence of a boat by acoustical cues under water (especially when diving) rather than through the air.…”

Use of an INLA Latent Gaussian Modeling Approach to Assess Bird Population Changes Due to the Development of Offshore Wind Farms

“…Members of the diver family (Gaviidae) are among the seabird species most susceptible to human disturbance in the North Sea (Garthe and Hüppop, 2004;Furness et al, 2013). Divers show avoidance behavior toward vessels at distances of more than one kilometer (Bellebaum et al, 2006;Fliessbach et al, 2019) and show reduced densities in areas of high ship traffic (Schwemmer et al, 2011;Burger et al, 2019). Many studies have been conducted into reactions of divers to offshore wind farms, consistently reporting avoidance behavior toward the wind farm itself and lower sighting rates within a certain buffer zone around the wind farm (Dierschke et al, 2016;Mendel et al, 2019;Allen et al, 2020;Heinänen et al, 2020).…”

Integrating Wind Turbines and Fish Farms: An Evaluation of Potential Risks to Marine and Coastal Bird Species

“…Given the turbine sizes and designs used in this study, we have assumed that these impacts will be less pronounced when compared with commercial offshore wind farms. Divers and seaducks are examples of species known to be sensitive to disturbance [55,56], and an attempt was made to include this sensitivity through the interaction factor G: Foraging around fish farms. It is presently unclear whether wind turbine-derived deterrence effects might be different from those deterrent effects caused by salmon farms themselves, including through regular human presence, boat movements, artificial lighting, etc.…”