The Bay of Brest is a semi-enclosed basin of 180 km2 subject to tidal dynamics and to the fluvial influences of both Aulne and Elorn Rivers, which drain watersheds representing 2600 km2 around the Bay, the major one being the Aulne River catchment. This coastal environment, at the land-sea interface, is subject to natural climate oscillations, typical of the North Atlantic Basin, with the superimposed paleoenvironmental transformations inherited from the post-glacial sea level rise and the anthropogenic forcing increasing from the Neolithic (6,950 ka BP) and especially from the Bronze Age (4,200 ka BP). Therefore, it is an ideal site for the reconstruction of the interactions and retroactions between climate, environment and human dynamics at the western tip of Brittany. To that end, a Holocene paleoenvironmental study was conducted thanks to eight cores collected around the Bay of Brest in four different subtidal areas (i.e., the Roscanvel Bay, the Brest Harbour, the South of the Plougastel peninsula and the mouth of the Aulne River) more or less impacted by oceanic vs. fluvial influences. First, a spatial comparison of pollen and dinoflagellate cyst (or dinocyst) assemblages (terrestrial and aquatic bioindicators, respectively) was conducted thanks to cores retrieved at the mouth of the Aulne River (twin cores "F" and "KS22"; major fluvial influence) and close to the Brest Harbour (twin cores "KS06" and "KS05"; increasing oceanic influence), on same time intervals encompassing 200 years: i) first around 4 ka BP and ii) second around 1 ka BP. Both spatial comparisons allowed recognizing fluvialpalynological tracers among palynological assemblages (Alnus and Corylus for pollen taxa; L. machaerophorum for dinocyst ones). This spatio-temporal investigation was then discussed in parallel with palynological data acquired on the southern Brittany shelf over the last 7 kyrs BP (core CBT-CS11). This allowed discussing the synchronous character of environmental observations considered as regional for western France (i.e., the general decline of the forest cover and related increase in Poaceae testifying of the landscape opening) and also local characteristics specific of Bay of Brest watersheds and linked to paleo-regimes of winter precipitation regimes above northern Europe (cf. NAO-like configurations). Then, in a second step, a stack of the eight Bay of Brest study cores was established to discuss the paleo-landscape evolution over the last 9 kyrs BP in this macro-tidal estuarine environment. Since the Neolithic period, the forest cover decreased in favour of open landscapes, including cultivated and grazed areas, in connection with the development of agriculture, or wastelands in the case of the metal industry. Nevertheless, the rate of opening of the landscape did not follow the "exponential" trend of herbaceous taxa: the forest cover slowly declined around 4 ka BP, then strongly decreased at the end of the Iron Age, before experiencing a revival of about 5 centuries at the end of the Gallo-Roman period. This latter period is discussed at the light of archaeological evidences of withdrawal of coastal societies in Brittany potentially echoing a climate deterioration combined to an unfavourable socio-economic context. Finally, a drastic fall is recorded at the start of the Middle Ages and is related to the population dynamics around the Brest Harbour and in particular to intensive agro-pastoral practices. This study therefore represents the first long-term Holocene trend of Bay of Brest paleo-landscapes allowing discussing both climatic and anthropogenic forcing thanks to the permanent change of scale performed when interpreting very local signals (Bay of Brest) face to macro-regional evidences of climate and environmental changes thanks to north-eastern Atlantic marine records.