Objective: This activity aims at filling the existing gaps in terms of the behaviour of HNS spilled at sea, their impact in the ecosystems and in key marine species, and implementing the obtained knowledge at operational level. Actions: 2.1. Revision of available information:  - 2.1.1. Revision on the fate and weathering of HNS involved in previous spill incidents.  - 2.1.2. Review of the fate, behaviour and weathering of priority HNS in sea water and shoreline environments focusing on the environment and public health impacts. 2.2. Experimental tests:  - 2.2.1. Determination of acute and chronic toxicity of priority HNS upon representatives of different aquatic animal taxa.  - 2.2.2. Determination of bioaccumulation and biomagnification of priority HNS in selected taxa based on laboratory studies.  - 2.2.3. Validatation of ecological modelling to predict the population level-impact of priority HNS. 2.3. Implementation at operation level:  - 2.3.1. Planning and preparedness for specific chemical risks and response.  - 2.3.2. Development of response protocols and definition of equipments.  - 2.3.3. Production of guidelines for monitoring and environmental impact assessment to be used by local authorities in response to spills.  - 2.3.4. Collection of information on the available R&D expertise and competencies for conducting monitoring and environmental impact assessment in partners’ regions. Managing partner: CIIMAR Contributing partners: Health Protection Agency, Cefas, INTECMAR, National Maritime College of Ireland (NMCI), Pembrokeshire County Council.