title: Detection and effects of harmful algal toxins in Scottish harbour seals and potential links to population decline.
abstract: Over the past 15 years or so, several Scottish harbour seal (Phoca vitulina) populations have declined in abundance and several factors have been considered as possible causes, including toxins from harmful algae. Here we explore whether a link could be established between two groups of toxins, domoic acid (DA) and saxitoxins (STXs), and the decline in the harbour seal populations in Scotland. We document the first evidence that harbour seals are exposed to both DA and STXs from consuming contaminated fish. Both groups of toxins were found in urine and faeces sampled from live captured (n = 162) and stranded animals (n = 23) and in faecal samples collected from seal haul-out sites (n = 214) between 2008 and 2013. The proportion of positive samples and the toxins levels measured in the excreta were significantly higher in areas where harbour seal abundance is in decline. There is also evidence that DA has immunomodulatory effects in harbour seals, including lymphocytopenia and monocytosis. Scottish harbour seals are exposed to DA and STXs through contaminated prey at potentially lethal levels and with this evidence we suggest that exposure to these toxins are likely to be important factors driving the harbour seal decline in some regions of Scotland.
authors: Sea Mammal Research Unit and Marine Alliance for Science and Technology Scotland, Scottish Oceans Institute, University of St. Andrews, St. Andrews, KY16 8LB, UK. Electronic address: siljekristinjensen@gmail.com.
authors: Silje-Kristin
authors: SK
authors: Jensen
authors: Marine Laboratory, Marine Scotland Science, 375 Victoria Road, Aberdeen, AB11 9DB, UK.
authors: Jean-Pierre
authors: JP
authors: Lacaze
authors: Marine Laboratory, Marine Scotland Science, 375 Victoria Road, Aberdeen, AB11 9DB, UK.
authors: Guillaume
authors: G
authors: Hermann
authors: Sea Mammal Research Unit and Marine Alliance for Science and Technology Scotland, Scottish Oceans Institute, University of St. Andrews, St. Andrews, KY16 8LB, UK.
authors: Joanna
authors: J
authors: Kershaw
authors: Scotland's Rural College, Drummondhill, Stratherrick Road, IV2 4JZ, UK.
authors: Andrew
authors: A
authors: Brownlow
authors: Cefas, Barrack Road, The Nothe, Weymouth, Dorset, DT4 8UB, UK.
authors: Andrew
authors: A
authors: Turner
authors: Sea Mammal Research Unit and Marine Alliance for Science and Technology Scotland, Scottish Oceans Institute, University of St. Andrews, St. Andrews, KY16 8LB, UK.
authors: Ailsa
authors: A
authors: Hall
mesh_terms: D000818:Animals; D004781:Environmental Exposure; D004797:Enzyme-Linked Immunosorbent Assay; D005243:Feces / Q000737:chemistry; D005399:Fishes / Q000378:metabolism; D020387:Food Chain; D006854:Hydrocortisone / Q000097:blood; D007608:Kainic Acid / Q000031:analogs & derivatives* / Q000378:metabolism / Q000652:urine; D007958:Leukocyte Count; D008387:Marine Toxins / Q000378:metabolism* / Q000652:urine; D046049:Phoca / Q000378:metabolism* / Q000652:urine; D011157:Population Dynamics; D012530:Saxitoxin / Q000378:metabolism* / Q000652:urine; D012606:Scotland
chemical_list: D008387:Marine Toxins; D012530:Saxitoxin; C012301:domoic acid; D007608:Kainic Acid; D006854:Hydrocortisone
keywords: Domoic acid (DA); HABs; Marine mammal; Paralytic Shellfish Poisoning (PSP) toxins; Phoca vitulina; Scotland