ALBERT

Description: A high-resolution carbonate C-isotope (δ13Ccarb) stratigraphy for the Aptian is presented for the Cau core from Alicante, Spain. The studied succession, lower to upper Aptian, embraces the record of the Early Aptian OAE 1a. The data provided includes δ13Ccarb, δ18O isotopes, Total Organic Carbon (TOC) and CaCO3. Four overlapping cores (D1 to D4) were drilled with an almost 100% recovery of a total (corrected for dip) thickness of 143 m. The cores were split in two parts. One half was described, photographed and scanned, and then sampled with a drill to obtain powdered samples for geochemical analyses. Also, small solid samples were taken from the drill for biostratigraphic characterization of the nannofossil and planktonic foraminifera associations. Second half was stored for archive and future research.

Description: Physical oceanography variables and carbon flux (for juveniles/adults of dominant mesopelagic migratory species) were determined during the CAPEGOLCA XIII and CAPEGOLCA XIV cruises (June-October 2018). This dataset contains the depth, temperature, and conductivity that were recorded with a Star-ODDI CTD attached to a Bongo net during CAPEGOLCA XIII and with a SeaBird SB11 CTD attached to an oceanographic rosette in CAPEGOLCA XIV. Values of numerical abundance, migrant biomass, specific respiration and respiration flux data for each individual of fishes, decapods and large euphausiids analyzed at the north-central regions in the Gulf of California are given. Specimens were collected during the nighttime (20:00–05:00 h local) using a standard Bongo net (0.61 m mouth diameter, 505 µm mesh net). The integrated layer from maximum depth to surface (32–272 m) was evaluated through oblique hauls for each cruise. Collected specimens were identified on board to the lowest possible taxonomic level and those selected for electron transfer system (ETS) activity analysis were immediately frozen in liquid nitrogen contained for posterior chemical analyses in the land-based laboratory. Values of abundance, migrant biomass, specific respiration and respiration flux were integrated from sampling depth to surface.

Description: Depth, temperature, and conductivity were recorded with a Star-ODDI CTD attached to a Bongo net during CAPEGOLCA XIII and half of CAPEGOLCA XIV (stations 36–101), and additionally with a calibrated SeaBird SB11 CTD attached to an oceanographic rosette for stations 4–95 during CAPEGOLCA XIV in October 2018.

Description: The values of carbon flux were determined in juveniles/adults of 3 species of migratory mesopelagic fishes, 2 species of decapods and 2 species of large euphausiids sampled during the CAPEGOLCA XIII and CAPEGOLCA XIV cruises (June-October 2018). This dataset contains the values of numerical abundance, migrant biomass, specific respiration and respiration flux data for each individual analyzed at the north-central regions in the Gulf of California. Specimens were collected during the nighttime (20:00–05:00 h local) using a standard Bongo net (0.61 m mouth diameter, 505 µm mesh net). The integrated layer from maximum depth to surface (32–272 m) was evaluated through oblique hauls for each cruise. Collected specimens were identified on board to the lowest possible taxonomic level and those selected for electron transfer system (ETS) activity analysis were immediately frozen in liquid nitrogen contained for posterior chemical analyses in the land-based laboratory. Values of abundance, migrant biomass, specific respiration and respiration flux were integrated from sampling depth to surface.

Description: Documenting changes in distribution is necessary for understanding species' response to environmental changes, but data on species distributions are heterogeneous in accuracy and resolution. Combining different data sources and methodological approaches can fill gaps in knowledge about the dynamic processes driving changes in species-rich, but data-poor regions. We combined recent bird survey data from the Neotropical Biodiversity Mapping Initiative (NeoMaps) with historical distribution records to estimate potential changes in the distribution of eight species of Amazon parrots in Venezuela. Using environmental covariates and presence-only data from museum collections and the literature, we first used maximum likelihood to fit a species distribution model (SDM) estimating a historical maximum probability of occurrence for each species. We then used recent, NeoMaps survey data to build single-season occupancy models (OM) with the same environmental covariates, as well as with time- and effort-dependent detectability, resulting in estimates of the current probability of occurrence. We finally calculated the disagreement between predictions as a matrix of probability of change in the state of occurrence. Our results suggested negative changes for the only restricted, threatened species, Amazona barbadensis, which has been independently confirmed with field studies. Two of the three remaining widespread species that were detected, Amazona amazonica, Amazona ochrocephala, also had a high probability of negative changes in northern Venezuela, but results were not conclusive for Amazona farinosa. The four remaining species were undetected in recent field surveys; three of these were most probably absent from the survey locations (Amazona autumnalis, Amazona mercenaria and Amazona festiva), while a fourth (Amazona dufresniana) requires more intensive targeted sampling to estimate its current status. Our approach is unique in taking full advantage of available, but limited data, and in detecting a high probability of change even for rare and patchily-distributed species. However, it is presently limited to species meeting the strong assumptions required for maximum-likelihood estimation with presence-only data, including very high detectability and representative sampling of its historical distribution.

Description: The continental shelf adjacent to the Río de la Plata (RdlP) exhibits extremely complex hydrographic and ecological characteristics which are of great socioeconomic importance. Since the long-term environmental variations related to the atmospheric (wind fields), hydrologic (freshwater plume), and oceanographic (currents and fronts) regimes are little known, the aim of this study is to reconstruct the changes in the terrigenous input into the inner continental shelf during the late Holocene period (associated with the RdlP sediment discharge) and to unravel the climatic forcing mechanisms behind them. To achieve this, we retrieved a 10 m long sediment core from the RdlP mud depocenter at 57 m water depth (GeoB 13813-4). The radiocarbon age control indicated an extremely high sedimentation rate of 0.8 cm per year, encompassing the past 1200 years (AD 750-2000). We used element ratios (Ti / Ca, Fe / Ca, Ti / Al, Fe / K) as regional proxies for the fluvial input signal and the variations in relative abundance of salinity-indicative diatom groups (freshwater versus marine-brackish) to assess the variability in terrigenous freshwater and sediment discharges. Ti / Ca, Fe / Ca, Ti / Al, Fe / K and the freshwater diatom group showed the lowest values between AD 850 and 1300, while the highest values occurred between AD 1300 and 1850. The variations in the sedimentary record can be attributed to the Medieval Climatic Anomaly (MCA) and the Little Ice Age (LIA), both of which had a significant impact on rainfall and wind patterns over the region. During the MCA, a weakening of the South American summer monsoon system (SAMS) and the South Atlantic Convergence Zone (SACZ), could explain the lowest element ratios (indicative of a lower terrigenous input) and a marine-dominated diatom record, both indicative of a reduced RdlP freshwater plume. In contrast, during the LIA, a strengthening of SAMS and SACZ may have led to an expansion of the RdlP river plume to the far north, as indicated by higher element ratios and a marked freshwater diatom signal. Furthermore, a possible multidecadal oscillation probably associated with Atlantic Multidecadal Oscillation (AMO) since AD 1300 reflects the variability in both the SAMS and SACZ systems.