Coastal Evolution in a Mediterranean Microtidal Zone: Mid to Late Holocene Natural Dynamics and Human Management of the Castelló Lagoon, NE Spain

RESEARCH ARTICLE Coastal Evolution in a Mediterranean Microtidal Zone: Mid to Late Holocene Natural Dynamics and Human Management of the Castelló Lagoon, NE Spain Ana Ejarque1,2*, Ramon Julià3, Jane M. Reed4, Francesc Mesquita-Joanes5, Javier MarcoBarba5, Santiago Riera3 a11111 1 CNRS, UMR 6042, GEOLAB, 4 rue Ledru, F-63057 Clermont-Ferrand cedex 1, France, 2 Université Clermont Auvergne, Université Blaise Pascal, GEOLAB, BP 10448, F-63000 Clermont-Ferrand, France, 3 Seminary of Prehistoric Studies and Research, Department of Prehistory, Ancient History and Archaeology, University of Barcelona, 08001, Barcelona, Spain, 4 Department of Geography, Environment and Earth Sciences, University of Hull, Cottingham Road, Hull, HU6 7RX, United Kingdom, 5 Cavanilles” Institute of Biodiversity and Evolutionary Biology, University of València, Av. Dr. Moliner, 50, E-46100, Burjassot, Spain * OPEN ACCESS Citation: Ejarque A, Julià R, Reed JM, MesquitaJoanes F, Marco-Barba J, Riera S (2016) Coastal Evolution in a Mediterranean Microtidal Zone: Mid to Late Holocene Natural Dynamics and Human Management of the Castelló Lagoon, NE Spain. PLoS ONE 11(5): e0155446. doi:10.1371/journal. pone.0155446 Editor: João Miguel Dias, University of Aveiro, PORTUGAL Received: January 27, 2016 Accepted: April 28, 2016 Published: May 13, 2016 Copyright: © 2016 Ejarque et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the paper and its Supporting Information files. Funding: This research was funded by the INTERAMBAR (CGL2009-12676-C02-01) and TerAmAr (HAR2012-39087-C02-0) projects from the Spanish Ministry of Economy and Competitiveness. It also received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 655659 (ULISSES project). The funders had no Abstract We present a palaeoenvironmental study of the Castelló lagoon (NE Spain), an important archive for understanding long-term interactions between dynamic littoral ecosystems and human management. Combining geochemistry, mineralogy, ostracods, diatoms, pollen, non-pollen palynomorphs, charcoal and archaeo-historical datasets we reconstruct: 1) the transition of the lagoon from a marine to a marginal environment between ~3150 cal BC to the 17th century AD; 2) fluctuations in salinity; and 3) natural and anthropogenic forces contributing to these changes. From the Late Neolithic to the Medieval period the lagoon ecosystem was driven by changing marine influence and the land was mainly exploited for grazing, with little evidence for impact on the natural woodland. Land-use exploitation adapted to natural coastal dynamics, with maximum marine flooding hampering agropastoral activities between ~1550 and ~150 cal BC. In contrast, societies actively controlled the lagoon dynamics and become a major agent of landscape transformation after the Medieval period. The removal of littoral woodlands after the 8th century was followed by the expansion of agrarian and industrial activities. Regional mining and smelting activities polluted the lagoon with heavy metals from the ~11th century onwards. The expansion of the milling industry and of agricultural lands led to the channelization of the river Muga into the lagoon after ~1250 cal AD. This caused its transformation into a freshwater lake, increased nutrient load, and the infilling and drainage of a great part of the lagoon. By tracking the shift towards an anthropogenically-controlled system around ~750 yr ago, this study points out Mediterranean lagoons as ancient and heavily-modified systems, with anthropogenic impacts and controls covering multi-centennial and even millennial timescales. Finally, we contributed to the future construction of reliable seashell-based chronologies in NE Spain PLOS ONE | DOI:10.1371/journal.pone.0155446 May 13, 2016 1 / 28 Mid to Late Holocene Natural Dynamics and Human Management of the Castelló Lagoon, NE Spain role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. by calibrating the Banyuls-sur-Mer ΔR offset with ceramic imports from the Emporiae archaeological site. Competing Interests: The authors have declared that no competing interests exist. Introduction Coastal lagoons are shallow basins connected to the sea by one or more inlets between barrier islands. They form in gently sloping coasts where sea level is rising relative to the shoreline. The relationships between tidal regime, size of the inlets, freshwater inflow, precipitation/evaporation ratios and basin morphology exert a strong influence on water exchange with the adjacent sea, internal circulation, suspended sediment transport and water salinity of the lagoon [1, 2]. These characteristics make coastal lagoons unique aquatic ecosystems, which are characterized by high sensitivity to natural and anthropogenic forcing [3, 4]. Mediterranean lagoons are highly productive ecosystems and since prehistoric times have constituted a vital natural resource for human communities. The range of ecosystem services provided is large, including food production, both within (e.g. shellfish, birds, fish) and around lagoons (e.g. cropping, pasturelands), and industrial exploitation such as salt works, soap and commercial fisheries [5, 6]. Their function as centres of human population benefits also from the proximity of lagoons to river deltas, ensuring freshwater supply. Millennia of coupled climatic-environmental and human exploitation for agriculture, industry and urban development have deeply impacted lagoonal landscapes, contributing to the contraction and loss of littoral wetlands [5]. Coastal lagoons provide invaluable sedimentary archives by which to reconstruct the longterm evolution of the coastal zone, with potential to disentangle the relative influence of climate change, sea-level change and human impact [7, 8]. This knowledge can contribute significantly to predictions of future coastline response to anthropogenic and natural forcing, and to development of sustainable management strategies for the conservation of endangered natural and cultural resources in coastal areas [9]. Geomorphological and palaeoecological research on Mediterranean lagoons has expanded considerably over the last decade. Studies performed in Greece [10, 11], Italy [12, 13]; France [8, 14, 15], and south-eastern Spain [16, 17] have unraveled natural and anthropogenic triggers in the Holocene evolution of coastal landscapes, underlining the intense human exploitation of lagoonal areas from the Neolithic to the present day. However, there are few detailed and well-dated studies of lagoonal ecosystems in NE Spain integrating palaeoecological and archaeo-histor (...truncated)