A multiproxy study of sediment cores from Zoñar Lake (37°29′00″N, 4°41′22″W, 300 m a.s.l.) suppor... more A multiproxy study of sediment cores from Zoñar Lake (37°29′00″N, 4°41′22″W, 300 m a.s.l.) supported by 11 14C AMS dates provides the first high-resolution centennial-scale reconstruction of past humidity changes in southern Spain during the last 4000 years. Arid periods occurred prior to 2.9 cal. kyr BP and during 1.3—0.6 cal. kyr BP (`Mediaeval Climate Anomaly'). The most humid period occurred during 2.6—1.6 cal. kyr BP encompassing the late Iron Age—Iberian and Roman epochs. Two humid periods of lower intensity occurred between 0.8 and 0.6 cal. kyr BP (AD 1200—1400) and about 400 cal. yr BP (around AD 1600) coinciding with the onset of the `Little Ice Age'. Humid conditions are synchronous with a decline in solar output and seem to correspond to atmospheric patterns similar to negative NAO phases. Arid conditions show better correlation with northern Africa climate evolution, suggesting a possible link to subtropical dynamics. The geographic location of Zoñar Lake and the...
The black-necked grebe Podiceps nigricollis is a relatively scarce species but, likewise, a regul... more The black-necked grebe Podiceps nigricollis is a relatively scarce species but, likewise, a regular feature of the sheltered coastal waters of Galicia. In this paper a review is presented on its phenology, wintering population, distribution, habitat preferences and trends, based on bibliographic material, unpublished observations and the results of the Waterfowl January Census. The species was present mainly from November to March, with numerical peaks between January and February. In recent years (2002-06) its population in January was evaluated between 187 and 272 individuals and over 80% was supported by the coastal sites of Ribadeo, Ferrol and Arousa. With 80% of the records and 97% of the individuals recorded between 1993 and 2006, rias and estuaries were the most favoured habitats. Moreover, population proportions remained constant in both habitats between 1988-92 and 2002-06. However, record frequency in different habitats experienced a significant seasonal variation, with many more records than expected in rias during winter and more in wetlands (estuaries, lagoons and reservoirs) during autumn and spring. Grebes were located on extensive open waters, with depth ranges of 2-7 m and polihaline-euhaline salinity regimes in the major sites of the rias of Ferrol and Arousa. Its wintering population showed a strong upward trend between 1988 and 2006, with annual growth rates of 15.6% to 18.7% (according to different log-linear regression models). The increases were particularly pronounced in Ferrol and Arousa.
Lake Chungará (18º15'S, 69º09'W, 4520 m a... more Lake Chungará (18º15'S, 69º09'W, 4520 m asl 22.5 Km2 and 40 m of water depth) is a hydrologically closed lake located on the Andean Altiplano. The lake is polymictic, meso to eutrophic and currently primary productivity is mainly governed by diatoms and ...
The status of the Great Northern Diver Gavia immer in Galicia, northwest Spain, is reviewed. Numb... more The status of the Great Northern Diver Gavia immer in Galicia, northwest Spain, is reviewed. Numbers peaked in late autumn and early winter, and again in spring. Post-breeding moult was recorded from November to mid December. Individuals in flight feather moult were recorded between February and March, the rest of the pre-breeding moult extending until the last birds departed around mid May. It is suggested that new birds arrive in the area in early spring to moult, replacing part of the wintering population. The species showed a strong preference for exposed sandy coasts in all seasons, but particularly in late winter and spring. The wintering population declined markedly following the Prestige oil spill in 2002/03 (c. 57% from 2002 to 2005). After 2005 the population returned to previous levels, possibly through immigration of birds from the nearby region of Asturias, where the wintering population collapsed in the same period. The average wintering population (uncorrected for detectability) was 123 birds (95% CI = 76–166), c. 2.5% of the estimated European wintering population.
The rocky and indented coast of NW Iberia is characterized by the presence of highly valuable and... more The rocky and indented coast of NW Iberia is characterized by the presence of highly valuable and vulnerable, small and shallow barrier–lagoon systems structurally controlled. The case study was selected to analyse barrier–lagoon evolution based on detailed sedimentary architecture, chronology, geochemical and biological proxies. The main objective is to test the hypothesis of structural control and the significance at regional scale of any high-energy event recorded. This work is also aimed at identifying general patterns and conceptualizing the formation and evolution of this type of coastal systems. The results allowed us to establish a conceptual model of Holocene evolution that applies to rock-bounded barrier–lagoon systems. The initial stage (early Holocene) is characterized by freshwater peat sedimentation and ended by marine flooding. The timing of the marine flooding depends on the relation between the elevation of the basin and the relative mean sea-level position; the lower the topography, the earlier the marine inundation. Thus, the age of basin inundation ranged from 8 to 4 ka BP supporting significant structural differences. Once marine inundation occurred, all systems followed similar evolutionary patterns characterized by a phase of landward barrier migration and aeolian sedimentation towards the back-barrier (i.e. retrogradation) that extended circa 3.5 ka BP. The later phases of evolution are characterized by a general trend to the stabilization of the barriers and the infilling of the lagoons. This stabilization may be temporally interrupted by episodes of enhanced storminess or sediment scarcity. In this regard, washover deposits identified within the sedimentary architecture of the case study explored here suggest pervasive high-energy events coeval with some of the cooling events identified in the North Atlantic during the mid- to late Holocene.
High-resolution laminated lacustrine sediments are excellent archives of the past hydrological ch... more High-resolution laminated lacustrine sediments are excellent archives of the past hydrological changes and they provide valuable insights about the climatic processes that trigger these changes. The paleoclimatic records located in the Southern Hemisphere are fundamental for understanding the evolution of the El Niño - Southern Oscillation (ENSO) since this climatic phenomena is the main cause of droughts and floods in many areas of South America and other regions of the world, like Spain and Egypt. Available regional paleoclimate reconstructions show that modern climatic patterns in South America were established during the Late Holocene. The laminated sediments of Lago Chungará (18° 15' S - 69° 10' W, 4520 m a.s.l., Chilean altiplano) have allowed us to characterize the evolution of this climatic phenomena for the transition Late Glacial - Early Holocene (12,300 - 9,500 calendar years BP) as well as its relationship with other climate forcings, namely the solar activity. T...
Azores archipelago lies in the southern area of the dipole that defines the North Atlantic Oscill... more Azores archipelago lies in the southern area of the dipole that defines the North Atlantic Oscillation (NAO). During the negative phase of the NAO, the Azores high pressure is displaced southwards allowing the storms to cross the islands increasing the precipitation in this area and also in southern Europe. This fact makes them excellent key places to perform accurate high-resolution climate reconstructions. Lake Azul (37o 52' 21"N - 37o52'21"W) is a monomictic lake infilling the volcanic complex of Sete Cidades which is located in São Miguel island. This monomictic and eutrophic lake was formed around 22000 cal. years B.P. by consecutive collapses of the underneath volcanic caldera. The last eruption of the Sete Cidades crater complex was radiocarbon-dated at 500-650 cal years B.P. At present, macrophytes are restricted to the lake shore and consist mainly of Potamogeton spp., Myriophyllum alterniflorum, Ceratophyllum demersum, Nymphaea alba, and, Chara fragilis. ...
A multiproxy study of sediment cores from Zoñar Lake (37°29′00″N, 4°41′22″W, 300 m a.s.l.) suppor... more A multiproxy study of sediment cores from Zoñar Lake (37°29′00″N, 4°41′22″W, 300 m a.s.l.) supported by 11 14C AMS dates provides the first high-resolution centennial-scale reconstruction of past humidity changes in southern Spain during the last 4000 years. Arid periods occurred prior to 2.9 cal. kyr BP and during 1.3—0.6 cal. kyr BP (`Mediaeval Climate Anomaly'). The most humid period occurred during 2.6—1.6 cal. kyr BP encompassing the late Iron Age—Iberian and Roman epochs. Two humid periods of lower intensity occurred between 0.8 and 0.6 cal. kyr BP (AD 1200—1400) and about 400 cal. yr BP (around AD 1600) coinciding with the onset of the `Little Ice Age'. Humid conditions are synchronous with a decline in solar output and seem to correspond to atmospheric patterns similar to negative NAO phases. Arid conditions show better correlation with northern Africa climate evolution, suggesting a possible link to subtropical dynamics. The geographic location of Zoñar Lake and the...
The black-necked grebe Podiceps nigricollis is a relatively scarce species but, likewise, a regul... more The black-necked grebe Podiceps nigricollis is a relatively scarce species but, likewise, a regular feature of the sheltered coastal waters of Galicia. In this paper a review is presented on its phenology, wintering population, distribution, habitat preferences and trends, based on bibliographic material, unpublished observations and the results of the Waterfowl January Census. The species was present mainly from November to March, with numerical peaks between January and February. In recent years (2002-06) its population in January was evaluated between 187 and 272 individuals and over 80% was supported by the coastal sites of Ribadeo, Ferrol and Arousa. With 80% of the records and 97% of the individuals recorded between 1993 and 2006, rias and estuaries were the most favoured habitats. Moreover, population proportions remained constant in both habitats between 1988-92 and 2002-06. However, record frequency in different habitats experienced a significant seasonal variation, with many more records than expected in rias during winter and more in wetlands (estuaries, lagoons and reservoirs) during autumn and spring. Grebes were located on extensive open waters, with depth ranges of 2-7 m and polihaline-euhaline salinity regimes in the major sites of the rias of Ferrol and Arousa. Its wintering population showed a strong upward trend between 1988 and 2006, with annual growth rates of 15.6% to 18.7% (according to different log-linear regression models). The increases were particularly pronounced in Ferrol and Arousa.
Lake Chungará (18º15'S, 69º09'W, 4520 m a... more Lake Chungará (18º15'S, 69º09'W, 4520 m asl 22.5 Km2 and 40 m of water depth) is a hydrologically closed lake located on the Andean Altiplano. The lake is polymictic, meso to eutrophic and currently primary productivity is mainly governed by diatoms and ...
The status of the Great Northern Diver Gavia immer in Galicia, northwest Spain, is reviewed. Numb... more The status of the Great Northern Diver Gavia immer in Galicia, northwest Spain, is reviewed. Numbers peaked in late autumn and early winter, and again in spring. Post-breeding moult was recorded from November to mid December. Individuals in flight feather moult were recorded between February and March, the rest of the pre-breeding moult extending until the last birds departed around mid May. It is suggested that new birds arrive in the area in early spring to moult, replacing part of the wintering population. The species showed a strong preference for exposed sandy coasts in all seasons, but particularly in late winter and spring. The wintering population declined markedly following the Prestige oil spill in 2002/03 (c. 57% from 2002 to 2005). After 2005 the population returned to previous levels, possibly through immigration of birds from the nearby region of Asturias, where the wintering population collapsed in the same period. The average wintering population (uncorrected for detectability) was 123 birds (95% CI = 76–166), c. 2.5% of the estimated European wintering population.
The rocky and indented coast of NW Iberia is characterized by the presence of highly valuable and... more The rocky and indented coast of NW Iberia is characterized by the presence of highly valuable and vulnerable, small and shallow barrier–lagoon systems structurally controlled. The case study was selected to analyse barrier–lagoon evolution based on detailed sedimentary architecture, chronology, geochemical and biological proxies. The main objective is to test the hypothesis of structural control and the significance at regional scale of any high-energy event recorded. This work is also aimed at identifying general patterns and conceptualizing the formation and evolution of this type of coastal systems. The results allowed us to establish a conceptual model of Holocene evolution that applies to rock-bounded barrier–lagoon systems. The initial stage (early Holocene) is characterized by freshwater peat sedimentation and ended by marine flooding. The timing of the marine flooding depends on the relation between the elevation of the basin and the relative mean sea-level position; the lower the topography, the earlier the marine inundation. Thus, the age of basin inundation ranged from 8 to 4 ka BP supporting significant structural differences. Once marine inundation occurred, all systems followed similar evolutionary patterns characterized by a phase of landward barrier migration and aeolian sedimentation towards the back-barrier (i.e. retrogradation) that extended circa 3.5 ka BP. The later phases of evolution are characterized by a general trend to the stabilization of the barriers and the infilling of the lagoons. This stabilization may be temporally interrupted by episodes of enhanced storminess or sediment scarcity. In this regard, washover deposits identified within the sedimentary architecture of the case study explored here suggest pervasive high-energy events coeval with some of the cooling events identified in the North Atlantic during the mid- to late Holocene.
High-resolution laminated lacustrine sediments are excellent archives of the past hydrological ch... more High-resolution laminated lacustrine sediments are excellent archives of the past hydrological changes and they provide valuable insights about the climatic processes that trigger these changes. The paleoclimatic records located in the Southern Hemisphere are fundamental for understanding the evolution of the El Niño - Southern Oscillation (ENSO) since this climatic phenomena is the main cause of droughts and floods in many areas of South America and other regions of the world, like Spain and Egypt. Available regional paleoclimate reconstructions show that modern climatic patterns in South America were established during the Late Holocene. The laminated sediments of Lago Chungará (18° 15' S - 69° 10' W, 4520 m a.s.l., Chilean altiplano) have allowed us to characterize the evolution of this climatic phenomena for the transition Late Glacial - Early Holocene (12,300 - 9,500 calendar years BP) as well as its relationship with other climate forcings, namely the solar activity. T...
Azores archipelago lies in the southern area of the dipole that defines the North Atlantic Oscill... more Azores archipelago lies in the southern area of the dipole that defines the North Atlantic Oscillation (NAO). During the negative phase of the NAO, the Azores high pressure is displaced southwards allowing the storms to cross the islands increasing the precipitation in this area and also in southern Europe. This fact makes them excellent key places to perform accurate high-resolution climate reconstructions. Lake Azul (37o 52' 21"N - 37o52'21"W) is a monomictic lake infilling the volcanic complex of Sete Cidades which is located in São Miguel island. This monomictic and eutrophic lake was formed around 22000 cal. years B.P. by consecutive collapses of the underneath volcanic caldera. The last eruption of the Sete Cidades crater complex was radiocarbon-dated at 500-650 cal years B.P. At present, macrophytes are restricted to the lake shore and consist mainly of Potamogeton spp., Myriophyllum alterniflorum, Ceratophyllum demersum, Nymphaea alba, and, Chara fragilis. ...
Uploads
Papers