TY - JOUR T1 - Long-term evolution (1988-2008) of Zostera spp. meadows in Arcachon Bay (Bay of Biscay) A1 - Plus,Martin A1 - Dalloyau,Sebastien A1 - Trut,Gilles A1 - Auby,Isabelle A1 - de Montaudouin,Xavier A1 - Emery,Eric A1 - Noel,Claire A1 - Viala,Christophe AD - IFREMER, LER AR, F-33120 Arcachon, France. AD - Univ Bordeaux 1, CNRS, UMR EPOC 5805, Stn Marine Arcachon, F-33120 Arcachon, France. AD - IFREMER, LER PAC, F-83507 La Seyne Sur Mer, France. AD - SEMANTIC TS, F-83110 Sanary, France. UR - https://doi.org/10.1016/j.ecss.2010.01.016 DO - 10.1016/j.ecss.2010.01.016 KW - seagrass KW - temporal evolution KW - aerial photography KW - acoustic sonar KW - Zostera noltii KW - Zostera marina KW - Arcachon Bay N2 - The spatial variability of seagrass meadows in Arcachon Bay, was studied between 1988 and 2008 using a combination of mapping techniques based on aerial photographs for intertidal dwarf-grass (Zostera noltti) beds and acoustic sonar for permanently submerged eelgrass (Zostera marina) populations. The results show a severe decline over the period for both species, as well as an acceleration of the decline since 2005 for Z. noltii. The total surface regression over the studied period is estimated to be 22.8 km(2) for Z. noltii and 2.7 km(2) for Z. marina, which represent declines of 33 and 74% respectively. Environmental data time series spanning the same period were investigated in order to seek the causes for such a decline. The calculated inter-annual trends for temperature, salinity, nitrate plus nitrite, ammonia, suspended sediment and chlorophyll a did not identify any clear environmental change capable of explaining the observed seagrass regression. For instance, no evident sign of eutrophication was observed over the study period. On the other hand, we suggest that the observed variations of ammonia in the inner part of the lagoon are a symptom of the seagrasses' disappearance and thus, a first sign indicating a change of the Arcachon Bay ecosystem towards more instability and vulnerability. Several hypotheses to explain the observed seagrass decay are proposed. (C) 2010 Elsevier Ltd. All rights reserved. Y1 - 2010/04 PB - Academic Press Ltd- Elsevier Science Ltd JF - Estuarine Coastal And Shelf Science SN - 0272-7714 VL - 87 IS - 2 SP - 357 EP - 366 ID - 11376 ER -