Eutrophication modelling chain for improved management strategies to prevent algal blooms in the Bay of Seine

Type Article
Date 2016-02
Language English
Author(s) Passy Paul1, 2, 3, Le Gendre RomainORCID4, 8, Garnier Josette1, 2, 5, Cugier Philippe6, Callens Julie1, 2, Paris Francois4, 7, Billen Gilles1, 2, 5, Riou Philippe4, Romero Estela1, 2
Affiliation(s) 1 : CNRS, 4 Pl Jussieu, F-75005 Paris, France.
2 : Univ Paris 06, FIRE FR 3020, 4 Pl Jussieu, F-75005 Paris, France.
3 : Natl Univ Singapore, Dept Geog, 1 Arts Link, Singapore 117570, Singapore.
4 : IFREMER, LER N, Ave Gen Gaulle, F-14520 Port En Bessin, France.
5 : Univ Paris 06, UMR 7619, 4 Pl Jussieu, F-75005 Paris, France.
6 : IFREMER, Ctr Bretagne, Dyneco LEBCO, CS 10070, F-29280 Plouzane, France.
7 : Bur Rech Geol & Minieres, Coastal Risks & Climate Change Unit, Risks & Prevent Div, 3 Av C Guillemin,BP 36009, Orleans 45, France.
8 : IFREMER, Unite Rech Lagons Ecosyst & Aquaculture Durable L, BP 2059, Noumea 98846, New Caledonia.
Source Marine Ecology Progress Series (0171-8630) (Inter-research), 2016-02 , Vol. 543 , P. 107-125
DOI 10.3354/meps11533
WOS© Times Cited 27
Keyword(s) Eutrophication, Harmful algal blooms, Nutrient load, Modelling, Water quality, Seine
Abstract Eutrophication of the Seine estuary and the Bay of the Seine is a crucial environmental issue for the management of ecosystems and economic activities related to fisheries and tourism. A large quantity of nutrients, especially nitrogen, is brought to the coastal zone by the Seine River, the main input of that area, but also by smaller rivers along the Normandy coast. This large delivery of nitrogen leads to an imbalance between nitrogen (N), phosphorus (P) and silica (Si), which affects the growth of planktonic organisms and can exacerbate the occurrence of harmful algal blooms (HABs). These events can be damaging for shellfish fisheries, an important economic resource for the region. The study describes a new modelling chain coupling a riverine and a marine model (the Seneque/Riverstrahler and the ECOMARS-3D, respectively), which allows us to explore the effects on the coast of two scenarios of watershed management. The first one, focused on an upgrade of wastewater treatment plants, decreases the P fluxes by 5–35 kgP km-2 yr-1 on average over the 2000–2006 period, depending on the watershed, and would reduce about three fold the concentration of dinoflagellates in the adjacent coastal zone. The second one explores a hypothetical scenario of generalisation of organic farming on all agricultural areas of the basin. Although this is not realistic, it shows the best theoretical results we can achieve. With this scenario the N fluxes decrease by almost 50%, and the dinoflagellate blooms and thus possibly the Dinophysis sp. blooms are drastically reduced by a factor of 20–40. Nevertheless, diatoms, which are the main primary producers in the bay and sustain the marine food web, are not significantly affected by this drastic scenario.
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Passy Paul, Le Gendre Romain, Garnier Josette, Cugier Philippe, Callens Julie, Paris Francois, Billen Gilles, Riou Philippe, Romero Estela (2016). Eutrophication modelling chain for improved management strategies to prevent algal blooms in the Bay of Seine. Marine Ecology Progress Series, 543, 107-125. Publisher's official version : https://doi.org/10.3354/meps11533 , Open Access version : https://archimer.ifremer.fr/doc/00300/41103/