Description: Here, we present 23 water physical (temperature, dissolved oxygen, pH, conductivity) and chemical (major anions Cl-, SO42-, CO32-, HCO3- and cations Ca2+, K+, Mg2+, Na+), sedimentological (total carbon (TC), total inorganic carbon (TIC), total organic carbon (TOC), total nitrogen (TN)), mineralogical (quartz, carbonate, phyllosilicates and feldspars) and geological (altitude, bedrock type and age of sediments) variables of aquatic systems of the Northern Neotropical region. Sampling was conducted in 76 aquatic systems during July-October 2013, coinciding with the rainy season in the region. Sampling sites are located on the Yucatán Peninsula Mexico (n=28), Guatemala (n=26), El Salvador (n=14), Honduras (n=5) and Nicaragua (n=3). We aim to identify limnological regions based on the measured variables and to infer the influence of geodiversity in observed patterns. Water physical and chemical variables were measured in situ with a WTW Multi Set 350i multiparameter probe at a water depth of 0.5 m. Water samples for analysis of major anions and cations were collected at water depths of 0.5 m below surface. TC and TN in sediments contents were determined by combustion with a LECO TruSpec Macro CHN analyzer. TIC was quantified with a Woesthoff Carmhograph C-16. TOC was calculated by subtracting TIC from TC. Qualitative and semi-quantitative mineralogical compounds were examined by x-ray diffraction with a RIGAKU Miniflex600. ArcGIS software was used to identify geological attributes of sampling sites such as bedrock and age of sediments. Altitude, latitude, and longitude were determined with the navigator Garmin GPSmap 60c.

Description: The following database contains freshwater ostracode relative abundances from littoral and sediment surface samples of 76 aquatic ecosystems of the Northern Neotropical region. Samples were collected during July-October 2013, coinciding with the rainy season in the region. Sampling sites are located on the Yucatán Peninsula Mexico (n=28), Guatemala (n=26), El Salvador (n=14), Honduras (n=5) and Nicaragua (n=3). Ostracode species were used to test their potential as bioindicators of (paleo) climate change and anthropogenic impact in aquatic ecosystems of the region. At littoral areas, we sampled between submerged vegetation using a 250 µm mesh hand net, whereas sediment samples were collected from the deepest bottom using an Ekman grab. Ostracode extraction and counting was carried out using 15 cm3 of each sample. Species identification was undertaken using individual adult specimens with complete soft parts. When identification down the species level was not possible, we assigned a putative species name (e.g., “Cyprideis sp 1”).

Description: Inorganic geochemistry data (Ti, Al, Ca, Fe, and Mn) and mineralogy of sediments from Lake Petén Itzá are presented. Lake Petén Itzá was drilled in 2006 by the International Continental Discovery Program, obtaining seven lacustrine sedimentary records: PI-01, PI-02, PI-03, PI-04, PI-06, PI-7, and PI-9. Here, we present data from site PI-02 located north of the lake (16°59'58.04''N; 89°44'41.51''W) and measured between 67 and 19 m depth. Inorganic geochemistry data were obtained by X-ray fluorescence (XRF) using a Cox Analytical Itrax Core Scanner (Cr tube, 30 kV, 55 mA, 15 s exposure) with a resolution of 1 cm. XRF data is displayed in counts per second (cps). Subsequently, a transformation to centered log-ratio (CLR) was performed. The CLR data were obtained by dividing each value by the geometric mean of the elements measured at said depth, then the natural logarithm of said quotient was obtained. CLR results have no units. The mineralogy data were obtained every 1 m by ray diffraction (XRD) using a Rigaku MiniFlex 600 equipment (15 mA/40kV) in a rotation axis between 3 and 80°. The XRD values are in relative percentages obtained using the X-Pert High Score software (version 1.0b) and the diffraction potential files of the International Center for Diffraction Data, USA. Depth data corresponds with the master composite sequence presented by Mueller et al. (2010), while age data belongs to the age-depth model presented by Martínez-Abarca et al. 2023.

Description: Highlights • Evaluation of environmental variability induced by Heinrich Stadials (HS5a-HS1) in continental northern Neotropical region. • Multiproxy evidence reveals mild temperature decreases and drastic fluctuations in precipitation during HSs. • Ultrastructure of HSs suggests individual environmental response of each Stadial making them contrasting from each other. • Most drastic climate changes induced by HSs exerted positive effects on diversity of aquatic communities. Abstract We reconstruct environmental conditions of the period 53-14 kyr BP in the continental northern Neotropical region. We evaluate in detail the magnitude of climatic fluctuations and their effects on aquatic communities during six Heinrich Stadials (HS1-HS5a), using sediments from Lake Petén Itzá, Guatemala, and a multiproxy approach. In Lake Petén Itzá typical Heinrich Stadials (HSs) are recorded in sediments as alternations of gypsum and clay, and abrupt changes in magnetic susceptibility, CaCO3 and biological compositions. This suggests that HSs were periods of hydrological unbalance, characterized by dry spells, punctuating the predominant humid conditions characterizing the period 53-14 kyr BP. The ultrastructure of HSs allows us to identify four different types of climatic conditions associated to HSs: 1) prevailing dry conditions but changing to humid (HS5, HS3); 2) predominantly humid conditions but changing to arid (HS2); 3) fluctuating humid-dry-humid (HS4, HS1); and 4) arid with high lake water conductivity (HS5a). The continuous presence of tropical ostracode species during HSs suggests that lake water temperatures were not drastically lowered. Ostracode-based transfer functions indicate that during HSs, epilimnetic water temperatures decreased by 1–3 °C compared to mean modern temperatures. Lake solute composition and conductivity were strongly affected by HSs. During HS5a and HS1 we estimate conductivity values 〉 800 μS cm−1. Diversity indices show significant differences (F5,70 = 3.74, p = 0.004) of ostracode species composition among HSs. Highest diversities occurred during HS5a, HS4 and HS1, which display greater climatic alterations than the other HSs. Fluctuating climates seem to have exerted positive effects on diversity of aquatic communities by producing an increase in habitat heterogeneity.

Description: We evaluated how ranges of four endemic and non-endemic aquatic ostracode species changed in response to long-term (glacial–interglacial cycles) and abrupt climate fluctuations during the last 155 kyr in the northern Neotropical region. We employed two complementary approaches, fossil records and species distribution models (SDMs). Fossil assemblages were obtained from sediment cores PI-1, PI-2, PI-6 and Petén-Itzá 22-VIII-99 from the Petén Itzá Scientific Drilling Project, Lake Petén Itzá, Guatemala. To obtain a spatially resolved pattern of (past) species distribution, a downscaling cascade is employed. SDMs were reconstructed for the last interglacial (∼120 ka), the last glacial maximum (∼22 ka) and the middle Holocene (∼6 ka). During glacial and interglacial cycles and marine isotope stages (MISs), modelled paleo-distributions and paleo-records show the nearly continuous presence of endemic and non-endemic species in the region, suggesting negligible effects of long-term climate variations on aquatic niche stability. During periods of abrupt ecological disruption such as Heinrich Stadial 1 (HS1), endemic species were resilient, remaining within their current areas of distribution. Non-endemic species, however, proved to be more sensitive. Modelled paleo-distributions suggest that the geographic range of non-endemic species changed, moving southward into Central America. Due to the uncertainties involved in the downscaling from the global numerical to the highly resolved regional geospatial statistical modelling, results can be seen as a benchmark for future studies using similar approaches. Given relatively moderate temperature decreases in Lake Petén Itzá waters (∼5 ∘C) and the persistence of some aquatic ecosystems even during periods of severe drying in HS1, our data suggest (1) the existence of micro-refugia and/or (2) continuous interaction between central metapopulations and surrounding populations, enabling aquatic taxa to survive climate fluctuations in the northern Neotropical region.