Imprints of the Little Ice Age and the severe earthquake of AD 2001 on the aquatic ecosystem of a tropical maar lake in El Salvador

Using a 530-year sediment record from the maar Lake Apastepeque, El Salvador, and based on diverse geochemical and biological (cladocerans, chironomids, diatoms, ostracods, testate amoebae) indicators, we estimated climatic and environmental alterations during the Little Ice Age (LIA) and reconstructed the recent history of the lake. Results demonstrate relatively humid conditions in the mid-elevations (500 m a.s.l.) of El Salvador during most parts of the LIA, resulting in high lake levels. Contrarily, the first part of the LIA was characterized by drier climates comparable to studies from Mexico and Belize, which correlated this phase with the Spörer minimum. Regional comparison with palaeorecords from the northern Neotropics reveals a high heterogeneity in local expressions of the LIA in Central America, likely connected to the high topographic heterogeneity of the region. Since the beginning of the 20th century, Lake Apastepeque has experienced enhanced human impact expressed as increased nutrient supply. The most recent period was characterized by significant environmental disturbance, which we relate to an upper-crustal earthquake, one of the strongest over the last 500 years, that affected the region on 13th February 2001 (Mw = 6.6, epicentre at 10 km depth, 30 km from the lake). The release of toxic bottom components such as hydrogen sulphide and high turbidity and turbulence of water caused major species turnover in the lake ecosystem, resulting in a massive fish kill and colonization by large cladocerans. Modern sediments still show slightly altered biota communities compared to pre-earthquake assemblages, indicating that the ecosystem has still not fully recovered

Accumulation of elements in vegetation spontaneously developing on self-heating waste dumps in the Upper Silesia area (Poland)

Accumulation of 34 trace and major elements was analysed in 9 plant species (Tussilago farfara, Arctium tomentosum, Solidago canadensis, Populus L., Eupatorium cannabinum, Verbascum sp., Solanum nigrum, Rumex crispus L., Betula pendula) and one fungus (Schizophyllum commune) collected from coal, PbZn-smelting, and mixed-type waste heaps in Upper Silesia (Poland). The most persistent and extreme enrichment was found in the burnt bark of Betula pendula from Bytom. Enrichment factors in relation to the geometric mean of elevated (PE) and hyperaccumulator (PH) plant contents show extreme values for elements toxic to vegetation, such as Zn (EFPE up to 13, EFPH up to 17), Pb (EFPH up to 4, EFPE up to 161), Tl (EFPE up to 8), Cd (EFmax of 327), Hg (EFPH up to 3), and Ag (maximum EFPE of 14). Elevated are also V (EFPN up to 13), Sc (EFPN up to 14), Ni (EFPN up to 17), Se (EFPN up to 16), Fe (EFPN up to 48), Co (EFPN up to 23), Sb (EFPN up to 31), and Bi (EFPN up to 34). Although the levels of the elements studied were usually below potentially toxic levels, they were often above the normal ones. Furthermore, significant differences in the contents between different plant tissues were observed, as reflected in the translocation factor (TF). Verbascum sp. and S. nigrum accumulate such elements mostly in their above-ground tissues, and may thus be considered useful in phytoextraction of Zn, Pb and other elements. Sl. canadensis and E. cannabinum mostly display the opposite strategy, with element immobilization in their roots. Extreme Zn contents in E. cannabinum, peaking in its roots, suggest it to be a potential Zn phytostabilizer

Cladocera Responses to the Climate-Forced Abrupt Environmental Changes Related to the Late Glacial/Holocene Transition

This article aims to trace in detail the periods of rapid changes during the Late Glacial period based on a subfossil Cladocera analysis and a palynological, geochemical, and statistical analysis. At the end of the Older Dryas, the water level in the reservoir was low, with quite cold waters and inconvenient conditions for developing Cladocera-dominated cold-tolerant species. The beginning of the Alleröd is marked by increasing vegetation density and a rising water temperature, with favorable conditions for developing rare species. At its end, there was a large diversity of species, along with the quite deep and rather mesotrophic nature of the water body. The beginning of the Younger Dryas is a shift back to conditions similar to those noticed during the Older Dryas. The shift to Holocene is manifested by a rapid increase in the number of species and abundance of planktonic forms that appeared before the Holocene onset. The high resolution of the research (1 cm sampling) allowed us to set up more precisely the boundaries between the stadials and interstadials of the Late Glacial and to find some species which were found in the sediment earlier than in previous studies

Tracking Fish Introduction in a Mountain Lake over the Last 200 Years Using Chironomids, Diatoms, and Cladoceran Remains

We analysed a 24 cm long sediment sequence (past ~200 years) from an alpine lake (Tatra Mts., Slovakia) for chironomids, cladocerans, and diatoms to reconstruct the effects of a historically documented fish introduction. Our results indicate that fish introduction predated the age of the sequence, and thus, we did not cover the lake’s fishless period. The individual proxies coincide in showing two main lake development stages. The first stage lasted until ~1950 CE and was interpreted as the stage when brown trout and alpine bullhead co-occurred. The extremely low concentration of cladocerans, the dominance of small-bodied chydorids, and the low share of daphnids, together with the low proportion/absence of large-bodied tanypod chironomids, suggest a strong effect of both species. The beginning of the next stage is probably related to the ban on fish manipulations and grazing in the catchment. A significant increase in the total abundance of cladocerans and of daphnids may indicate the extirpation of trout. The steep increase in thermally plastic chironomid taxa since the end of the 20th century indicates climate warming. Generally, while cladocerans primarily indicate fish manipulations, chironomids and diatoms mainly reflect other local and global environmental stressors

New Estimates of the Magnitude of the Sea-Level Jump during the 8.2 Ka Event

We analyzed sediment cores from coastal Lake Izabal, Guatemala, to infer Holocene biogeochemical changes in the lake. At ca. 8370 calibrated yr B.P. (cal. yr B.P.), marine waters entered the lake, which presently lies ~38 km from the Caribbean coast. Temporal correlation between Early Holocene drainage of high-latitude Lakes Agassiz and Ojibway (in North America) and marine flooding of Lake Izabal suggests a causal link between the two processes. Our data indicate a relative sea-level jump of 2.60 ± 0.88 m, which is larger than previous estimates of sea-level rise during the 8.2 ka event. The inferred sea-level jump, however, cannot be explained solely by the volume of water released during drainage of Lakes Agassiz and Ojibway. Instead, we propose that previous studies underestimated the magnitude of Lakes Agassiz and Ojibway discharge, or that additional meltwater sources contributed to global sea-level rise at that time

Imprints of the Little Ice Age and the severe earthquake of AD 2001 on the aquatic ecosystem of a tropical maar lake in El Salvador

Using a 530-year sediment record from the maar Lake Apastepeque, El Salvador, and based on diverse geochemical and biological (cladocerans, chironomids, diatoms, ostracods, testate amoebae) indicators, we estimated climatic and environmental alterations during the Little Ice Age (LIA) and reconstructed the recent history of the lake. Results demonstrate relatively humid conditions in the mid-elevations (500 m a.s.l.) of El Salvador during most parts of the LIA, resulting in high lake levels. Contrarily, the first part of the LIA was characterized by drier climates comparable to studies from Mexico and Belize, which correlated this phase with the Spörer minimum. Regional comparison with palaeorecords from the northern Neotropics reveals a high heterogeneity in local expressions of the LIA in Central America, likely connected to the high topographic heterogeneity of the region. Since the beginning of the 20th century, Lake Apastepeque has experienced enhanced human impact expressed as increased nutrient supply. The most recent period was characterized by significant environmental disturbance, which we relate to an upper-crustal earthquake, one of the strongest over the last 500 years, that affected the region on 13th February 2001 (Mw = 6.6, epicentre at 10 km depth, 30 km from the lake). The release of toxic bottom components such as hydrogen sulphide and high turbidity and turbulence of water caused major species turnover in the lake ecosystem, resulting in a massive fish kill and colonization by large cladocerans. Modern sediments still show slightly altered biota communities compared to pre-earthquake assemblages, indicating that the ecosystem has still not fully recovered.Fil: Wojewódka Przybył, Marta. Polish Academy of Sciences; ArgentinaFil: Krahn, Kim J.. Technische Universitat Carolo Wilhelmina Zu Braunschweig.; AlemaniaFil: Hamerlík, Ladislav. Matej Bel University; EslovaquiaFil: Macario González, Laura. Matej Bel University; EslovaquiaFil: Cohuo, Sergio. Technische Universitat Carolo Wilhelmina Zu Braunschweig.; AlemaniaFil: Charqueño Celis, Norma Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Cisneros, Anaís. Universidad Nacional Autónoma de México; MéxicoFil: Hoelzmann, Philipp. Freie Universität Berlin; AlemaniaFil: Yang, Handong. Colegio Universitario de Londres; Reino UnidoFil: Rose, Neil L.. Colegio Universitario de Londres; Reino UnidoFil: Zawisza, Edyta. Polish Academy of Sciences; ArgentinaFil: Pérez, Liseth. Technische Universitat Carolo Wilhelmina Zu Braunschweig.; AlemaniaFil: Schwalb, Antje. Technische Universitat Carolo Wilhelmina Zu Braunschweig.; Alemani