The two most common sources of continuous anthropogenic noise are shipping, and more recently, offshore wind turbines or wind farms. In order to understand the impacts of offshore wind farms on the marine environment, all aspects need to be understood - both the potential positive effects in terms of reduced take zones and increased habitat availability, as well as the negative effects in terms of changes in sediment-water dynamics and those of exposure to the continuous operational noise. As the knowledge on the effects of noise on invertebrates is still very limited, especially in comparison to the other effects, there is an urgent need to create the fundamental knowledge base by combining laboratory-based experimental work under controlled conditions, using different key organisms, and field observations and experiments.
Orchestra will investigate the effects of continuous underwater noise on the physiology, growth, reproduction, feeding, intraspecific communication, predator avoidance and mortality of key invertebrate species in multi-stressor laboratory setups. Further, the project will evaluate the potential ensuing cascading effects on the function of those species in the ecosystem. In addition, it will assess the validity of the results obtained in the laboratory and complement them by using a combination of sampling and experimental studies in the field at different distances to continuous boat and offshore wind noise sources. The results from these experiments will be checked against existing invertebrate species distribution and abundance data sets. Further, understanding the combined effects of underwater noise with climate warming is particularly relevant as underwater noise propagation changes with temperature, salinity and pressure and animal sensory organs can be affected by temperature. The project will uncover the conservational relevance of underwater noise on invertebrate-based food webs in a warming environment. In laboratory settings, Orchestra will cross underwater noise treatments with temperature treatments, in order to assess how these stressors interact. This is particularly relevant given that most poikilothermic organisms react strongly to changes in temperature, and higher temperatures may incur stress to those organisms, which could then be exacerbated by underwater noise in turn.
With that the objectives of ORCHESTRA are:
1) Evaluating the responses of selected invertebrates to continuous low-frequency noise. The response of individual organisms will be linked to physiological and behavioural response measurements. The molecular expression of genes associated with stress responses will provide information about the ecological performance or lifespan resulting from noise exposure.
2) Understanding how individual reaction norms of key species affect species interactions (predator-prey interactions), both in benthic communities, as well as in the pelagic zone, and shape invertebrate-based food webs and, in turn, biogeochemical cycles.
3) Predicting ecosystem consequences on larger scales, thus allowing the assessment of the impact of underwater noise on marine ecosystems and ultimately the prediction of potential implications in the age of 'Blue Growth'. Objective 3 will use the outcome of ORCHESTRA laboratory and field work and integrate this with existing literature and data sets about species distribution, plus abundance in the North Sea and Adriatic Sea soundscape/noise maps that can be obtained from assessments of locations of OWF and important shipping routes.
Maarten Boersma, Alfred Wegener Institute for Polar and Marine Research (Germany)
Christian-Albrecht University of Kiel, Germany
University of Padua, Italy
Ghent University, Belgium
The Norwegian Institute of Marine Research, Norway
The National Research Council, Italy