A combined
study of coccolith a
ssemblage
s and biomarker
s in a gravity core collected from the Ría de Vigo (NW Spain) allowed u
s to recon
struct the paleoenvironmental condition
s for the la
st 3000 year
s. The quantitative di
stribution of coccolithophore
specie
s point
s to three different interval
s within the core, dated by AMS radiocarbon mea
surement
s. The fir
st interval (ca. 975 BC–252 AD), characterized by high abundance
s of Calcidi
scu
s leptoporu
s and Gephyrocap
sa
muellerae, i
s thought to repre
sent moderate water temperature
s,
sugge
sting a tran
sition from a warmer to a cooler period. The
second interval (ca. 252–1368 AD), characterized by the dominance of Coccolithu
s pelagicu
s, Helico
sphaera carteri and Syraco
sphaera
spp., and a high concentration of hexaco
sanol linked to terre
strial input, i
s interpreted a
s having been a humid period with fluvial input. The third interval (ca. 1368 AD–1950) i
s characterized by a high abundance of Gephyrocap
sa oceanica, high alkenone value
s and low value
s of hexaco
sanol, and i
s thought to repre
sent a period dominated by oceanic condition
s within the Ría.
Taking into account the ocean–atmospheric system affecting the region studied, here we propose an alternation in the mean state of North Atlantic Oscillation (NAO) at millennial time scales. A well-developed upwelling system and an active Ría–ocean connection during the warmer interval I suggest a NAO+ phase influenced by a Hypsithermal period. The occurrence of the humid and relatively warm interval II is consistent with a negative phase in the NAO, as well as a relative restriction in ocean–Ría exchange. Interval III, which was drier and more productive, again suggests the dominance of a positive phase in the NAO, with a more intense oceanic connection and more energized upwelling.