Diatoms from small ponds and terrestrial habitats in Deserta Grande Island (Madeira Archipelago)

Freshwater diversity, and diatoms in particular, from Desertas Islands (Madeira Archipelago, Portugal) is poorly known, although the Islands are protected and became a Natural Reserve in 1995. During two field expeditions in 2013 and 2014 to Deserta Grande Island, several freshwater and terrestrial habitats were sampled. The analysis of these samples aims to contribute to the biodiversity assessment of the freshwater biota present in Deserta Grande Island. Here, we present the diatom diversity in Deserta Grande Island resulting from that survey. This study contributes to improve the knowledge of Madeira Archipelago freshwater diversity, particularly in the Desertas sub-archipelago.New information To our knowledge, we present the first diatom data for the Desertas sub-archipelago. This work resulted in a list of 60 diatom taxa for Deserta Grande, from which 57 were identified to species level. From the 60 new records for Desertas sub-archipelago, 30 of them were also new records for Madeira Archipelago. Several specimens could not be assigned to a known species and may be new diatom species not yet described.info:eu-repo/semantics/publishedVersio

The Vanishing and the Establishment of a New Ecosystem on an Oceanic Island: Anthropogenic Impacts With No Return Ticket

[Abstract] A multiproxy approach was applied to a sediment core retrieved from the deep crater Lake Funda, located in the middle of the North Atlantic Ocean on Flores Island, Azores archipelago (Portugal). The purpose of this study was to determine how this ecosystem responded to natural and anthropogenic forces over the last millennium. We distinguished three main phases in lake evolution using multiproxy reconstructions and documentary sources. (A) Climate and lake catchment processes, as well as internal ones, were the main drivers of ecosystem variability before 1335 CE, when human disturbances were absent in the Lake Funda catchment. (B) The second phase is marked by unprecedented changes in all studied proxies between 1335 and 1560 CE, including abrupt changes in the composition and diversity of diatom and chironomid assemblages. Synergistic effects from high climate variability and the onset of human disturbances in the catchment (e.g., introduction of livestock) during the Medieval Climate Anomaly-Little Ice Age transition, led to an increase in lake trophic state from mesotrophic to eutrophic conditions. (C) In the last phase (1560 CE to the present), the eutrophic conditions in Lake Funda were maintained through a positive feedback loop between lake productivity and in-lake phosphorous recycling. Variability within the lake ecosystem was mainly associated with climate variability and internal lake dynamics (e.g., phosphorus remobilization). Our results show that a paleoecological approach is crucial to understanding lake ecological states in the present-day in order to develop locally adapted management and restoration strategies. A long-term perspective enables us to understand the harmful consequences of ongoing climate change and human disturbances on lake ecosystems.The research was funded by the Portuguese Science Foundation (FCT) (DL57/2016/ICETA/EEC2018/25) and the DISCOVERAZORES (PTDC/CTA-AMB/28511/2017), together with the PaleoModes project (CGL2016-75281-C2) funded by the Spanish Ministry of Economy and Competitiveness, and the Luso-American Foundation. AH is funded by the Spanish Ministry of Science and Innovation through the Ramón y Cajal Scheme (RYC2020-029253-I)Portugal. Fundação para a Ciência e a Tecnologia; DL57/2016/ICETA/EEC2018/25Portugal. Fundação para a Ciência e a Tecnologia; PTDC/CTA-AMB/28511/201

Estabelecimento e multiplicação in vitro de Luehea divaricata Mart. & Zucc.

Luehea divaricata Mart. et  Zucc. (acoita-cavalo) of the Malvaceae family, is a forest-tree species that has suffered great anthropic disturbance during the last decades. This fact has contributed to the reduction of natural populations and, consequently, of its genetic variability. This justifies studies related to the propagation of the species. As a means of vegetative propagation, micropropagation is an alternative for the regeneration of plants with difficult natural regeneration and a strategy for species conservation. The objectives of this study were to determine the most efficient type of explant and growth medium for in vitro establishment and verify the influence of different concentrations of BAP cytokinin in the multiplication of nodal segments of Luehea divaricata. The seeds used were collected and stored by the Fundação Estadual de Pesquisa Agropecuária – FEPAGRO/Florestas (Agriculture and Cattle Research State Foundation – FEPAGRO/Forests), in Santa Maria, RS, Brazil, and the seedlings obtained in vitro were used as sources of the explants. In the selection of the explants and growth medium, the tips of stems and nodal segments grown in the MS and WMP nutritive media were tested. Different concentrations of BAP (0, 5, 10 and 15 mg L-1) were evaluated in the in vitro multiplication of the species. In the in vitro establishment of Luehea divaricata, both tips of stems and nodal segments can be used and also both growth media. To maximize the growth of the species, the WPM growth medium should be used due to its reduced cost. In the in vitro multiplication of the species, cytokinin BAP should not be added because, besides reducing the costs in the in vitro cultivation of Luehea divaricata, the best response for the majority of the characteristics evaluated was observed in the absence of this regulator,.O açoita-cavalo, Luehea divaricata Mart. & Zucc., pertencente à família Malvaceae, é uma espécie florestal que sofreu grande ação antrópica nas últimas décadas. Esse fato contribuiu muito para a redução das populações naturais e, consequentemente, de sua variabilidade genética, o que justifica a realização de estudos relacionados à propagação da espécie. Como forma de propagação vegetativa, a micropropagação torna-se uma opção para a regeneração de plantas que apresentam dificuldade de reprodução natural, além de ser uma estratégia para a conservação das espécies. O trabalho teve como objetivos determinar o tipo de explante e o meio de cultivo mais eficientes para o estabelecimento in vitro, além de verificar a influência de diferentes concentrações da citocinina BAP na multiplicação de segmentos nodais de açoita-cavalo. As sementes utilizadas foram coletadas e armazenadas pela Fundação Estadual de Pesquisa Agropecuária – FEPAGRO-Florestas em Santa Maria, RS e as plântulas obtidas in vitro foram utilizadas como fonte de explantes. Na seleção de explantes e meio de cultivo, foram testados segmentos apicais caulinares e segmentos nodais cultivados nos meios nutritivos MS e WPM. Diferentes concentrações de BAP (0, 5, 10 e 15 mg L-1) foram avaliadas na multiplicação in vitro de açoita-cavalo. No estabelecimento in vitro de açoita-cavalo podem-se empregar tanto segmentos apicais caulinares como segmentos nodais e ambos os meios de cultivo. Visando a maximizar o cultivo de açoita-cavalo, deve-se utilizar o meio de cultivo WPM, pelo custo reduzido. Na multiplicação in vitro de açoita-cavalo não deve ser adicionada a citocinina BAP, pois na ausência desse regulador se observa melhor resposta dos explantes para a maioria das características avaliadas, além de reduzir os custos no cultivo in vitro da espécie

Stream diatom community assembly processes in islands and continents: a global perspective

[EN] Understanding the roles of deterministic and stochastic processes in community assembly is essential for gaining insights into the biogeographical patterns of biodiversity. However, the way community assembly processes operate is still not fully understood, especially in oceanic islands. In this study, we examine the importance of assembly processes in shaping diatom communities in islands and continents, while also investigating the influence of climate and local water chemistry variables on species distributions. Location Global. Taxon Stream benthic diatoms. Methods We used diatom datasets from five continents and 19 islands and applied beta diversity analyses with a null model approach and hierarchical joint species distribution modelling. To facilitate comparisons with continents, we used continental area equivalents (CAEs), which represent continental subsets with comparable areas and the same number of study sites as their corresponding islands counterparts. Results We found that homogeneous selection (i.e., communities being more similar than the random expectation) was the dominant assembly process within islands whereas stochastic processes tended to be more important within continents. In addition, assembly processes were influenced by study scale and island isolation. Climatic variables showed a greater influence on species distribution than local factors. However, in islands, local environmental variables had a greater impact on the distributions of unique taxa as opposed to non-unique taxa. Main Conclusions We observed that the assembly processes of diatom communities were complex and influenced by a combination of deterministic and stochastic forces, which varied across spatial scales. In islands, there was no universal pattern of assembly processes, given that their influence depends on abiotic conditions such as area, isolation, and environmental heterogeneity. In addition, the sensitivity of species occurring uniquely in islands to local environmental variables suggests that they are perhaps less vulnerable to climatic changes but may be more influenced by changes in local physicochemistrySIFor financial support, the authors thank the Academy of Finland (grant nr. 346812 to JS); the Institut Francais de Finlande; the Embassy of France to Finland; the French Ministry of Education and Higher Education; Finnish Society of Sciences and Letters. J.J. Wang was further supported by the National Natural Science Foundation of China (91851117, 41871048), CAS Key Research Program of Frontier Sciences (QYZDB-SSW-DQC043), and The National Key Research and Development Program of China (2019YFA0607100

Climate change facilitated the early colonization of the Azores Archipelago during medieval times

Humans have made such dramatic and permanent changes to Earth's landscapes that much of it is now substantially and irreversibly altered from its preanthropogenic state. Remote islands, until recently isolated from humans, offer insights into how these landscapes evolved in response to human-induced perturbations. However, little is known about when and how remote systems were colonized because archaeological data and historical records are scarce and incomplete. Here, we use a multiproxy approach to reconstruct the initial colonization and subsequent environmental impacts on the Azores Archipelago. Our reconstructions provide unambiguous evidence for widespread human disturbance of this archipelago starting between 700 -60/+50 and 850 -60/+60 Common Era (CE), ca. 700 y earlier than historical records suggest the onset of Portuguese settlement of the islands. Settlement proceeded in three phases, during which human pressure on the terrestrial and aquatic ecosystems grew steadily (i.e., through livestock introductions, logging, and fire), resulting in irreversible changes. Our climate models suggest that the initial colonization at the end of the early Middle Ages (500 to 900 CE) occurred in conjunction with anomalous northeasterly winds and warmer Northern Hemisphere temperatures. These climate conditions likelyinhibited exploration from southern Europe and facilitated human settlers from the northeast Atlantic. These results are consistent with recent archaeological and genetic data suggesting that the Norse were most likely the earliest settlers on the islands

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

Disentangling the geologic, human and climate drivers influencing sediment deposition in volcanic lakes on the Azores Archipelago

IAL-IPA joint meeting "Lakes as Memories of the Landscape", Patagonia, Argentina, 27 November-01 December 2022The Azores Archipelago Western (AAWG) and Central (AACG) groups present a high diversity of tectono-volcanic settings, and, therefore, a wide range of lake-watershed system morphometries. This archipelago has suffered from anthropic impacts, mainly abrupt land-use changes, since medieval times (between 700 and 850 CE), and increasingly after the Portuguese arrival in the 15th century. In this complex geologic and human context, we used a multiproxy approach in sediment records from Lakes Caldeirão (Corvo Island), Funda (Flores Island), and Caveiro (Pico Island) to demonstrate a complex interlinking among several environmental drivers over the last millennia. Paleoenvironmental changes have been defined by a multivariate analysis of sedimentary facies, biogeochemical and mineralogical data. This analysis highlights that the most prominent sedimentary process in the AAWG lakes (Caldeirao and Funda) is hydrological grain size sorting, driven by runoff. Additionally, smooth catchment slopes of the low-gradient lake, Caldeirão, modulated this process by favouring rock grain size diminution through weathering, whereas the steep topographic-bathymetric profile of the high-gradient lake, Funda, do through water-level fluctuations. The frequent volcanic activity of the AACG and the small size of Caveiro lake catchment favoured the deposit of pyroclastic tephra through direct fallout in the lake, over the catchment-sourced inputs, reworked by climate and tectonic activity. The biogeochemical and mineral composition of the sedimentary records present extreme change rates at 1288+28-22-1388+41-32 CE, corresponding with the age of the most intense landscape transformation. Therefore, to obtain robust climate reconstructions from these Azorean lacustrine records, we present a detailed statistical approach to isolate the climate signal from volcano-tectonic, morphometric, and anthropic driversThis research was funded by the Spanish Ministry of Economy and Competitiveness research projects PaleoNAO (CGL2010-15767), RapidNAO (CGL2013-40608-R), PaleoModes (CGL2016-75281-C2), and NEOCLIM (PID2020-113798GB-C33), and through Portuguese Science Foundation (FCT) (DL57/2016/ICETA/EEC2018/25) and the DISCOVERAZORES (PTDC/CTA-AMB/28511/2017)N

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio