Threats to blue mussels — a European risk analysis Ane Timenes Laugen Centre for Coastal Research (CCR), Universitetet i Agder, Kristiansand NAEMO, Oban, 2019-10-30 Acknowedgements •Åsa Strand, IVL Swedish Environmental Institute •Kristina Svedberg, IVL & University of Gothenburg •Matthias Obst & Jon Havenhand, University of Gothenburg [Why] are blue mussels in decline? Human disturbance Coastal exploitation/ shoreline hardening • Direct damage (anchoring etc.) • Sediment dispersal & noise during construction Boat traffic • Turbulence (wave exposure, sediments) • Direct damage (anchoring etc.) • Noise Pollution • Engines • Toilets • Antifouling http://havsmiljo.se/media/fritidsbatars_miljopaverkan.pdf; https://en.wikipedia.org/wiki/Seawall#/media/File:Seawallventnor.jpg https://balticeye.org/sv/livsmiljoer/kustmiljobloggen/fritidsbatar-och-undervattensnatur/ Qualitative threat analysis Svedberg 2019. MSc thesis, Gothenburg University Eutrophication Increased presence of epibionts/fouling • reduced hard surface areas for settlement • increased energy allocation to byssus production • increased risk for dislodging Increased abundance of food 1 cm Buschbaum, C., & Saier, B. (2001). Growth of the mussel Mytilus edulis L. in the Wadden Sea affected by tidal emergence and barnacle epibionts. Journal of Sea Research, 45(1), 27–36 Biotoxins / pollution Algal toxins • reduced risk of algal blooms with decreased eutrophication • increased risk of algal blooms with increasing temperatures PAH • negative effect on M galloprovincialis (Cajaraville et al 1995) • little knowledge about effects of PCB, HCB, DDT PCB, HCB, DDT, others • more or less unknown Climate change Ocean warming • growth/reproduction • risk of disease • distribution range • epibionts/fouling Extreme weather • nutrient runoff • disturbance (ice, sediments, storms) Ocean acidification • growth/reproduction/survival Laugen, Strand, Havenhand, Obst (in prep) Invasive species Pacific oyster (Magallana gigas) • competition (space/food) • protection (fouling/predation) • settling surface Sea walnut (Crepidula fornicata) • competition (space/food) Common slipper shell (Mnemiopsis leidiy) • larval mortality Predation/pathogens Birds • eider populations varies in space and time Invertebrates • crabs and sea stars prefer mussels to pacific oysters Pathogens • spatiotemporal variation in outbreak risk • expected to increase with climate change Strand, Fredriksson & Laugen (in prep) Extending the risk assessment •From qualitative to quantitative whenever possible •Multidisciplinary (aquaculture/wild-harvest/ecology/evolution etc.) •International (from regional to European/North Atlantic) •Call for collaboration.