The interplay of climate change and human activity in the central Mediterranean region during the last millennia: the varved, multiproxy record of Lake Butrint (Albania)

Past Global Changes. Open Science Meeting (5º. 2017. Zaragoza)Butrint is a 21 m deep lagoon located at the Ionian Sea coast of Albania. Permanent water stratification led to the deposition of varved sediments during the last millennia. Variations in the thickness and/or presence of seasonal laminae (endogenic calcite, organic matter, and clay) indicate fluctuations in water salinity, bioproductivity, and runoff, resulting from the interplay of climate and anthropogenic forcing. The multi-proxy analysis (sedimentology, geochemistry, pollen and ostracods) of a 12 m long sediment core, supported by an age model through varve counting, radiocarbon and 137Cs dating, enables a precise reconstruction of environmental change in the central Mediterranean region during the last 4.5 cal kyrs BP. Additionally, the nearby archaeological site of Buthrotum, continuously populated from Greek times until the late 18th century AD, provides an exceptional record of human impact. Increasing siltation after the foundation of the city and subsequent farming and urbanization of the catchment led to the progressive isolation of the Butrint basin from an open bay to a restricted lagoon. Maximum clastic input at 500 AD likely coincides with the most intense farming during the Late Antiquity. Intervals of maximum water salinity and bioproductivity coincide with warmer conditions, such as the early Roman Warm Period (500 BC-0 AD) or the Medieval Climate Anomaly (800-1400 AD). Conversely, lower salinity, more oxic conditions, and higher runoff occurred during 1400-500 BC, Late Roman and Early Medieval times (0-800 AD), and during the Little Ice Age (1400-1800 AD). Ongoing research on microfacies and stable isotopes (δ 18O and δ 13C in authigenic calcite) allows a more precise reconstruction of the main hydrological changes in the lagoon during the last millennium. The sedimentary record of Lake Butrint demonstrates the complex interplay of climate variability and human impact in the recent evolution of coastal Mediterranean regions.Instituto Geológico y Minero de España, EspañaDepartamento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, EspañaInstitute of Geological Sciences and Oeschger Centre of Climate Change Research, University of Bern, SuizaDipartimento di Scienze della Terra, Sapienza University of Rome, ItaliaDepartment of Earth Sciences, University of Geneva, SuizaDepartamento de Procesos Geoambientales y Cambio Global, Instituto Pirenaico de Ecología, Consejo Superior de Investigaciones Científicas, EspañaDepartamento de Estratigrafía, Universidad Complutense de Madrid, EspañaDepartment of Geology and Mineralogy, University of Cologne, AlemaniaAlbanian Geological Survey, AlbaniaPeer reviewe

Human–climate interactions in the central Mediterranean region during the last millennia: The laminated record of Lake Butrint (Albania)

Lake Butrint (39°47 N, 20°1 E) is a ca. 21 m deep, coastal lagoon located in SW Albania where finely-laminated sediments have been continuously deposited during the last millennia. The multi-proxy analysis (sedimentology, high-resolution elemental geochemistry and pollen) of a 12 m long sediment core, supported by seven AMS radiocarbon dates and 137Cs dating, enable a precise reconstruction of the environmental change that occurred in the central Mediterranean region during the last ∼4.5 cal kyrs BP. Sediments consist of triplets of authigenic carbonates, organic matter and clayey laminae. Fluctuations in the thickness and/or presence of these different types of seasonal laminae indicate variations in water salinity, organic productivity and runoff in the lake's catchment, as a result of the complex interplay of tectonics, anthropogenic forcing and climate variability. The progradation of the Pavllo river delta, favoured by variable human activity from the nearby ancient city of Butrint, led to the progressive isolation of this hydrological system from the Ionian Sea. The system evolved from an open bay to a restricted lagoon, which is consistent with archaeological data. An abrupt increase in mass-wasting activity between 1515 and 1450 BC, likely caused by nearby seismic activity, led to the accumulation of 24 homogenites, up to 17 cm thick. They have been deposited during the onset of finely laminated sedimentation, which indicates restricted, anoxic bottom water conditions and higher salinity. Periods of maximum water salinity, biological productivity, and carbonate precipitation coincide with warmer intervals, such as the early Roman Warm Period (RWP) (500 BC–0 AD), the Medieval Climate Anomaly (MCA) (800–1400 AD) and recent times (after 1800 AD). Conversely, lower salinity and more oxic conditions, with higher clastic input were recorded during 1400–500 BC, the Late Roman and the Early Medieval periods (0–800 AD) and during the Little Ice Age (1400–1800 AD). Hydrological fluctuations recorded in Butrint are in phase with most central and western Mediterranean records and correlate with NAO variability. In contrast, opposite hydrological patterns have been recorded in the Eastern Balkans and the Levant during the last millennium, emphasizing a complex spatial variability in the region. Phases of maximum settlement intensity in Butrint (Roman-Late Antique) coincide with warmer and/or stable climate periods (0–800 AD and MCA, respectively), indicating a long-term influence of climatic conditions on human activities. The Late Holocene sedimentary record of Lake Butrint demonstrates the complex interplay of climate variability, tectonics and human impact in the recent evolution of coastal Mediterranean regions

Picking Up the PiecesHarmonising and Collating Seabed Substrate Data for European Maritime Areas

The poor access to data on the marine environment is a handicap to government decision-making, a barrier to scientific understanding and an obstacle to economic growth. In this light, the European Commission initiated the European Marine Observation and Data Network (EMODnet) in 2009 to assemble and disseminate hitherto dispersed marine data. In the ten years since then, EMODnet has become a key producer of publicly available, harmonised datasets covering broad areas. This paper describes the methodologies applied in EMODnet Geology project to produce fully populated GIS layers of seabed substrate distribution for the European marine areas. We describe steps involved in translating national seabed substrate data, conforming to various standards, into a uniform EMODnet substrate classification scheme (i.e., the Folk sediment classification). Rock and boulders form an additional substrate class. Seabed substrate data products at scales of 1:250,000 and 1:1 million, compiled using descriptions and analyses of seabed samples as well as interpreted acoustic images, cover about 20% and 65% of the European maritime areas, respectively. A simple confidence assessment, based on sample and acoustic coverage, is helpful in identifying data gaps. The harmonised seabed substrate maps are particularly useful in supraregional, transnational and pan-European marine spatial planning