High marsh foraminiferal assemblages' response to intra-decadal and multi-decadal precipitation variability, between 1934 and 2010 (Minho, NW Portugal)

摘要: Abstract Foraminiferal assemblages of Caminha tidal marshes have been studied since 2002 revealing a peculiar dominance brackish species, such as Haplophragmoides manilaensis , wilberti sp., Pseudothurammina limnetis and Trochamminita salsa / irregularis in the high Minho Coura lower estuaries. The assemblage composition reflects low salinity conditions, despite short distance to estuarine mouth (~ 4 km). However, May 2010, presence salt marsh species Trochammina inflata Jadammina macrescens became very significant, likely result 5 consecutive dry years corresponding rise sediment pore water. Correspondence analysis (CA) groups surface samples according their zone, showing positive correlation with submersion time each sampling point. normal foraminiferal appear separated CA. This observation was applied top 10 cm core that corresponds period instrumental record precipitation river flow region. We found strongly correlates Lima basins. longer was, therefore, used interpret assemblages' variability. Three main phases were distinguished along ca. 80 years data: 1) negative anomalies from 1934 1957; 2) 1958 1983; 3) 1984 2010. last dryer exhibits maximum greatest amplitude rainfall values. High foraminifera reveals fast response these short-term shifts; relative abundance increases when over several decades, well same decade, heavy periods. records increase freshwater flooding seepage by decreasing increasing species. On other hand, 5 years productivity between winter NAO index indicates region is part North Atlantic climate dynamics demonstrates may be high-resolution studies SW Europe evolution.