5/27（水）15時〜 EESセミナー開催について　

5月27日（水）15時から環境科学院C204-1室でEESセミナーを行います。
今回はノーザンミシガン大学で淡水生態系の研究をしているJill Leonardさんに、北米五大湖の移入種問題についてお話し頂きます。
外来二枚貝やハゼ科魚類の移入により在来種の食性が急速に変化したり、水鳥のボツリヌス中毒症に外来種が関与していそうなことなど、興味深い研究結果を報告して頂く予定です。
幅広い環境問題を扱っているため多くの方に興味を持って頂けると思います。
皆さまのご参加お待ちしております。

小泉逸郎

研究院アワーのお知らせ（EES seminar）
Time: 2015年5月27日（水）15:00-16:30bio-senko@ees.hokudai.ac.jp
Place: C204-1
Speaker: Dr. Jill B.K. Leonard
Chair: 小泉逸郎

Title: Great Lakes Invaders: Changes to the Lake Michigan Food Web and Their Links to Botulism Toxicity

Abstract:

The Laurentian Great Lakes in North America are the largest group of freshwater lakes in the world and contain ~21% of the surface freshwater on the planet. The lakes vary in ecological conditions from the relatively pristine and oligotrophic Lake Superior to the more eutrophic and anthropogenically impacted Lake Erie. All the lakes have been subjected to substantial human modification including water diversion, pollution, and non-native species introductions. While some non-native species introductions have been intentional (e.g. Pacific salmonids), many more have been unintentional and some of these species have caused dramatic ecological changes in the lakes. In two studies, we have been working to understand alterations caused by the introduction of dreissenid mussels (Dreissena spp.) and round goby (Neogobius melanostomus) in Lake Michigan.

First, we evaluated the change in diet of the piscivorous burbot (Lota lota) over a 16 year (1996-2012) sample series from eastern Lake Michigan. Burbot dramatically shifted their diet from alewife (Alosa pseudoharengus) and freshwater sculpin (Cottus spp.) to round goby. Goby first appeared in the diet in 1999 and became frequent in 2006 reaching ~56% of all items consumed by 2012. This change is important because it demonstrates the ability of this native predator to take advantage of a new, invasive, prey source. Our data also suggest that native predatory species may be able to impact invasive species population dynamics and bring nutrients sequestered to the lake bottom back up into the water column through round goby consumption.

In the second study, we also worked to understand the prey consumption dynamics of top-level predators; however, we focused on waterbirds such as the common loon (Gavia immer), piscivorous and molluscivorous ducks, and double crested cormorants (Phalacrocorax auritus) which have been the victims of botulism type E mortality in Lake Michigan. We were able to evaluate stomach contents of recently dead waterbirds collected from several areas in northern Lake Michigan and confirmed that most species had been feeding on round goby immediately before death. Several other species had fed substantially on dreissenid mussels. This data confirms that native species, including migratory waterbirds, are shifting their diet to the abundant invasive species in Lake Michigan and suggests two additional potential pathways for botulism to affect birds: directly through mussel consumption and less directly through the consumption of intoxicated round goby.