Stream diatom biodiversity in islands and continents—A global perspective on effects of area, isolation and environment

Aim The species-area relationship (SAR) is one of the most distinctive biogeographic patterns, but global comparisons of the SARs between island and mainland are lacking for microbial taxa. Here, we explore whether the form of the SAR and the drivers of species richness, including area, environmental heterogeneity, climate and physico-chemistry, differ between islands and similarly sized areas on mainland, referred to as continental area equivalents (CAEs). Location Global. Taxon Stream benthic diatoms. Methods We generated CAEs on six continental datasets and examined the SARs of CAEs and islands (ISAR). Then, we compared CAEs and islands in terms of total richness and richness of different ecological guilds. We tested the factors contributing to richness in islands and CAEs with regressions. We used structural equation models to determine the effects of area versus environmental heterogeneity, climate and local conditions on species richness. Results We found a non-significant ISAR, but a significant positive SAR in CAEs. Richness in islands was related to productivity. Richness in CAEs was mainly dependent on area and climate, but not directly on environmental heterogeneity. Species richness within guilds exhibited inconsistent relationships with island isolation and area. Main conclusions Ecological and evolutionary processes shaping diatom island biogeography do not depend on area at the worldwide scale probably due to the presence of distinct species pool across islands. Conversely, area was an important driver of diatom richness in continents, and this effect could be attributed to dispersal. Continents had greater richness than islands, but this was a consequence of differences in environmental conditions such as specific island climatic conditions. We stress the need for more island data on benthic diatoms, particularly from archipelagos, to better understand the biogeography of this most speciose group of algae

Long-term hydroclimate variability in the sub-tropical North Atlantic and anthropogenic impacts on lake ecosystems: A case study from Flores Island, the Azores

Human land use and climate change threaten ecosystems and natural resources, particularly on remote islands such as the Azores Archipelago in the North Atlantic. Since the official Portuguese settlement of the archipelago in the 15th and 16th centuries humans have extensively modified the Azorean landscape, with invasive plants dominating the present-day vegetation and evidence of eutrophication in numerous lakes. To evaluate changes in terrestrial and aquatic ecosystems in the Azores, we developed paleoecological and paleoclimate records from Lake Funda on Flores Island that span the last millennium. Changes in precipitation amount, as recorded by hydrogen isotopes from C30 fatty acids (δ Dwax), suggest that the climate was relatively stable between c. 1000–1400 CE. Recent evidence of early human settlers on the Azorean islands (c. 850–1300 CE) suggests that the introduction of livestock led to an increase in primary productivity in Lake Funda and other lakes in the Azores. More depleted δ Dwax values between c. 1500–1620 CE suggest that wetter climate conditions existed during the establishment of permanent settlements on Flores Island. Landscape changes between c. 1500–1600 CE coincided with an increase in primary productivity and hypoxic conditions in the lake bottom water, signifying the eutrophication of Lake Funda. Despite reforestation efforts in the Azores in the early 20th century and shift towards drier conditions, eutrophication in Lake Funda persisted. Reforestation efforts likely reduced nutrient leaching and soil erosion in the catchment area of Lake Funda and other Azorean lakes, yet eutrophication continues to be widespread. This highlights the lasting impacts of early human settlers on Lake Funda, and the need for more active remediation efforts.This work was supported by the Spanish Ministry of Economy and Competitiveness through the RapidNAO (CGL2013-40608-R) and PaleoModes (CGL2016-75281) projects, DiscoverAzores (PTDC/CTA AMB/28511/2017), a Luso-American Foundation “Crossing the Atlantic” grant, the Netherlands Earth Systems Science Center, the Institute at Brown for Environment and Society, and the Geological Society of America. Support for undergraduate research was provided by the Brown University Undergraduate Teaching & Research Awards. A. Hernández was funded by the Spanish Ministry of Science and Innovation through the Ramón y Cajal Scheme [RYC2020-029253-I]. We would like to thank everyone who participated in the 2017 and 2018 field campaigns to the Azores, in particular A. C. Costa and E. Zettler. We would like to thank J.S. Sinninghe Damste for support and advice. We would also like to thank J. Orchardo, E. Santos, and M. Baas for technical support and advice, and R. Vachula for advice.Peer reviewe

The Optical Instrumentation of the ATLAS Tile Calorimeter

The purpose of this Note is to describe the optical assembly procedure called here Optical Instrumentation and the quality tests conducted on the assembled units. Altogether, 65 Barrel (or LB) modules were constructed - including one spare - together with 129 Extended Barrel (EB) modules (including one spare). The LB modules were mechanically assembled at JINR (Dubna, Russia) and transported to CERN, where the optical instrumentation was performed with personnel contributed by several Institutes. The modules composing one of the two Extended Barrels (known as EBA) were mechanically assembled in the USA, and instrumented in two US locations (ANL, U. of Michigan), while the modules of the other Extended barrel (EBC) were assembled in Spain and instrumented at IFAE (Barcelona). Each of the EB modules includes a subassembly known as ITC that contributes to the hermeticity of the calorimeter; all ITCs were assembled at UTA (Texas), and mounted onto the module mechanical structures at the EB mechanical assembly locations.The Tile Calorimeter, covering the central region of the ATLAS experiment up to pseudorapidities of ±1.7, is a sampling device built with scintillating tiles that alternate with iron plates. The light is collected in wave-length shifting (WLS) fibers and is read out with photomultipliers. In the characteristic geometry of this calorimeter the tiles lie in planes perpendicular to the beams, resulting in a very simple and modular mechanical and optical layout. This paper focuses on the procedures applied in the optical instrumentation of the calorimeter, which involved the assembly of about 460,000 scintillator tiles and 550,000 WLS fibers. The outcome is a hadronic calorimeter that meets the ATLAS performance requirements, as shown in this paper

Mechanical construction and installation of the ATLAS tile calorimeter

This paper summarises the mechanical construction and installation of the Tile Calorimeter for the ATLAS experiment at the Large Hadron Collider in CERN, Switzerland. The Tile Calorimeter is a sampling calorimeter using scintillator as the sensitive detector and steel as the absorber and covers the central region of the ATLAS experiment up to pseudorapidities +/- 1.7. The mechanical construction of the Tile Calorimeter occurred over a period of about 10 years beginning in 1995 with the completion of the Technical Design Report and ending in 2006 with the installation of the final module in the ATLAS cavern. During this period approximately 2600 metric tons of steel were transformed into a laminated structure to form the absorber of the sampling calorimeter. Following instrumentation and testing, which is described elsewhere, the modules were installed in the ATLAS cavern with a remarkable accuracy for a structure of this size and weight

Data Descriptor : A European Multi Lake Survey dataset of environmental variables, phytoplankton pigments and cyanotoxins

Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent problem resulting from nutrient pollution and climate-change induced stressors, like poor transparency, increased water temperature and enhanced stratification. Consistency in data collection and analysis methods is necessary to achieve fully comparable datasets and for statistical validity, avoiding issues linked to disparate data sources. The European Multi Lake Survey (EMLS) in summer 2015 was an initiative among scientists from 27 countries to collect and analyse lake physical, chemical and biological variables in a fully standardized manner. This database includes in-situ lake variables along with nutrient, pigment and cyanotoxin data of 369 lakes in Europe, which were centrally analysed in dedicated laboratories. Publishing the EMLS methods and dataset might inspire similar initiatives to study across large geographic areas that will contribute to better understanding lake responses in a changing environment.Peer reviewe