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• A multi-proxy approach of late Holocene evolution from Valencia lagoon is presented. • A transition from coastal to fluvial processes shapes the lagoon morphology. • Between 2.8 and 1.2 ka, cold event is registered as a decline in marine influence. • A brackish marsh around 1.2 ka is contemporary with Medieval Climate Optimum. • In the last 0.8 ka, increased fluvial activity in the Little Ice Age is recorded. This study reconstructs the evolution of foraminiferal assemblages and the environmental variables (type of substrate, content in calcium carbonate and content in organic matter) in the Valencia lagoon (western Mediterranean) in response to changes in the late Holocene. In this area of low tidal range, several multiproxy analyses were carried out to determine which environmental variables influence the distribution of the fossil assemblage, and its association with global, regional or local climatic phenomena. The statistical results show that in environments with higher exposure to marine conditions, the calcium carbonate content is the dominant factor, whereas in more restricted environments the type of substrate (grain size) is determinant. The micropaleontological content reveals the evolution from a saline paleoenvironment with a clear marine influence towards the hyposaline or freshwater conditions, recorded at the top. Three phases were identified in the evolution of this area from 2800 cal yr BP to the present. A brackish lagoon with marine connection at the base, followed by a deposit of brackish lagoon (1232 ± 74 cal yr BP − 791 ± 104 cal yr BP), culminating in a brackish marsh (791 ± 104 cal yr BP to present), interpreted as the definitive closure process of the lagoon, favored by the coastal progradation processes related with an extraordinary input of sediments. These findings reflect the climatic variability of the Medieval Climate Optimum (MCO) (1.05 and 0.65 kcal BP) and the migration of the river Turia mouth, which favored the coastal progradation processes. The flood events registered at this phase, may have coincided with changes in the landscape and greater anthropic influence at the end of the LIA, 150 cal yr BP. Coastal processes are mainly responsible for the evolution of this area during phase I, while the influence of fluvial processes is significant towards the top, especially in phase III. [ABSTRACT FROM AUTHOR]

The Albufera de Valencia is one of the largest lagoon in the Spanish Mediterranean. Two continuous borehole cores reaching depths of 8 and 14 m in the northern part of the lagoon underwent sedimentological, micropaleontological and biological study. The organic content was also analysed, and 14 C radiometric dating and amino acid racemization were performed. Study of the content of benthic foraminifera and n-alkanes and alkanoic acids in the lagoon sedimentary record identified several periods. The core records showed seven different environments: alluvial; freshwater marsh; brackish marsh; brackish lagoon; brackish lagoon with marine connection, backbarrier flat, and backshore. These environments changed due to eight phases associated with the transgression and regression of the barrier system, which caused the shift from exposed environments as the backshore with washover, to the typical low-energy lagoon and marsh deposition. The paleoenvironmental evolution described above is interpreted as a response to global climate changes. The shift from an alluvial setting to a brackish lagoon is probably related to the late of Early Holocene sea level rise ending at the Holocene Climate Optimum, when the highest sea level was reached. The persistence of the brackish lagoon, with no marine connection, is probably synchronous with dry conditions in the area (Booth et al., 2005) at the time of Bond event 3 (i.e., 4.2 ka) in the North Atlantic region (Bond et al., 2001). Finally, the arrival of large amounts of sediment triggered the accretion of the barrier, also enhancing coastal progradation until the present day. These results allow an evaluation of the impact of anthropic action on the Valencia lagoon, especially since the eighteenth century, and a short- and medium-term projection of the consequences of present-day climate change., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The environmental variables that determine the distributions of benthic foraminiferal assemblages on the shoreface and inner shelf of the north of Valencia province (Western Mediterranean) are identified. The possible influence of variables such as water depth, distance from shore, hydrodynamics, substrate type, carbonate content, organic matter content and human activity is evaluated. Multivariate cluster-Q-type analysis and redundancy analysis (RDA) are used to identify the environmental variables that have the greatest influence on the assemblage distribution. The spatial distribution of the assemblages is closely associated with water depth and substrate. The diversity and abundance of foraminifera shells increase with depth and their conservation improves. The most common species in the study area are Ammonia beccarii, Rosalina globularis, Buccella granulata, Planorbulina mediterranensis, and Lobatula lobatula. The presence of wastewater in the study area has not polluted the foraminiferal assemblages (absence of anomalous shells). The direction of the discharge plume is a potential source of nutrients for deep water., (Copyright © 2014 Elsevier Ltd. All rights reserved.)