Eglantine Chappuis

Bio: Eglantine Chappuis is an academic researcher from Spanish National Research Council. The author has contributed to research in topics: Macrophyte & Aquatic plant. The author has an hindex of 14, co-authored 31 publications receiving 614 citations.

Global variation in the beta diversity of lake macrophytes is driven by environmental heterogeneity rather than latitude

Abstract: Additional co-authors: Gana Gecheva, Patrick Grillas, Jennifer Hauxwell, Seppo Hellsten, Jan Hjort, Mark V. Hoyer, Agnieszka Kolada, Minna Kuoppala, Torben Lauridsen, En‒Hua Li, Balazs A. Lukacs, Marit Mjelde, Alison Mikulyuk, Roger P. Mormul, Jun Nishihiro, Beat Oertli, Laila Rhazi, Mouhssine Rhazi, Laura Sass, Christine Schranz, Martin Sondergaard, Takashi Yamanouchi, Qing Yu, Haijun Wang, Xiao‒Ke Zhang, Jani Heino

Vertical zonation is the main distribution pattern of littoral assemblages on rocky shores at a regional scale

Abstract: Vertical variation in the distribution of rocky shore assemblages is greater than horizontal variation, as shown by univariate and multivariate analysis performed with data obtained along 1000 km of shoreline and covering from the upper supralittoral to the upper infralittoral zone (� 1 m). Consequently, vertical littoral zonation is a consistent pattern at a regional scale within the same biogeographical zone. While their distribution varies at the same shore height, marine species and assemblages from rocky shores show a specific vertical sequence known as zonation. A key question in ecology is how consistent is zonation along large spatial scales. The aim of this study is to show distribution patterns of littoral assemblages at a regional scale and to identify the most relevant abiotic factors associated to such patterns. The study is based on a detailed and extensive survey at a regional scale on a tideless rocky shore. Benthic

Macrophyte landscape modulates lake ecosystem‐level nitrogen losses through tightly coupled plant‐microbe interactions

Abstract: Root functional diversity of submerged vegetation exerts a major effect on nitrogen (N) cycling in lake sediments. This fact, however, is neglected in current N-balance models because the links between the engineering role of plants and in situ microbial N cycling are poorly understood. We hypothesized that macrophyte species with high root oxygen loss (ROL) capacity promote the highest denitrification because of a higher abundance of ammonia oxidizers and tighter coupling between nitrifiers and denitrifier communities. We sampled five small ultraoligotrophic shallow lakes with abundant macrophyte cover including sediments dominated either by Isoetes spp. (high ROL), mixed communities of natopotamids (low ROL), and unvegetated sandy sediments. At each site, we quantified denitrification (DNT) rates and proxies for the abundance of denitrifiers (nirS and nirK genes), and both ammonia oxidizing archaea (AOA) and ammonia oxidizing bacteria (AOB) and the diversity of nirS-harboring bacteria. Vegetated sediments showed significantly higher abundances of N-cycling genes than bare sediments. Plant communities dominated by Isoetes generated sediments with higher redox and NO3− concentrations and significantly higher DNT rates than natopotamids-dominated landscapes. Accordingly, increasing DNT rates were observed along the gradient from low ROL plants-bare sediments-high ROL plants. Significantly higher abundance of the archaeal amoA gene was recorded in sediments colonized by high ROL plants unveiling a key biogeochemical role for AOA in coupling macrophyte landscape and ecosystem denitrification.

Distribution and richness of aquatic plants across Europe and Mediterranean countries: patterns, environmental driving factors and comparison with total plant richness

Abstract: Questions What are the geographic patterns of γ-diversity of aquatic plants and what are the main driving factors? Are richness trends for aquatic plants similar to total plant richness? Is the Mediterranean area a hot spot for aquatic plants? Location Europe and the Mediterranean Basin. Material We listed vascular aquatic plant presence or absence for 44 countries. We also compiled total plant species richness and geographic and environmental variables for each country. Methods We first analysed country ordination based on their aquatic flora constrained by environmental variables (dbRDA), and selected the environmental variables best explaining species patterns (BEST analysis). Total species richness patterns were studied using maps and latitudinal gradients. We used generalized additive models (GAM) to detect the main environmental factors driving species richness, both for aquatic plants and total plants. Results The BEST analysis identified a single variable that best explains aquatic plant species distribution: evapotranspiration. However, richness of aquatic plants vs latitude varies and no clear trend was observed. No relation was found between total plant and aquatic plant richness. Aquatic and total plant richness peak between 40° and 50°N, and values were intermediate at low latitudes. GAM related aquatic plant richness with water resources and rainfall, while total plant richness is mainly driven by evapotranspiration and temperature. Hydrophytes were relatively more abundant at higher latitudes than helophytes and the ratio correlated with evapotranspiration. Conclusion Southern and western Europe hold the highest aquatic plant diversity, although no clear latitudinal species richness patterns were found. Aquatic plant richness is mainly driven by water-related variables. Total plant richness exhibits a latitudinal pattern influenced by the Sahara desert, which depresses richness at low latitudes. Best predictors of total plant richness patterns are water–energy variables.

A meta-analysis of nestedness and turnover components of beta diversity across organisms and ecosystems

Abstract: Aim The number of studies investigating the nestedness and turnover components of beta diversity has increased substantially, but our general understanding of the drivers of turnover and nestedness remains elusive. Here, we examined the effects of species traits, spatial extent, latitude and ecosystem type on the nestedness and turnover components of beta diversity. Location Global. Time period 1968–2017. Major taxa studied From bacteria to mammals. Methods From the 99 studies that partition total beta diversity into its turnover and nestedness components, we assembled 269 and 259 data points for the pairwise and multiple site beta-diversity metrics, respectively. Our data covered a broad variation in species dispersal type, body size and trophic position. The data were from freshwater, marine and terrestrial realms, and encompassed geographical areas from the tropics to near polar regions. We used linear modelling as a meta-regression tool to analyse the data. Results Pairwise turnover, multiple site turnover and total beta diversity all decreased significantly with latitude. In contrast, multiple site nestedness showed a positive relationship with latitude. Beta-diversity components did not generally differ among the realms. The turnover component and total beta diversity increased with spatial extent, whereas nestedness was scale invariant for pairwise metrics. Multiple site beta-diversity components did not vary with spatial extent. Surprisingly, passively dispersed organisms had lower turnover and total beta diversity than flying organisms. Body size showed a relatively weak relationship with beta diversity but had important interactions with trophic position, thus also affecting beta diversity via interactive effects. Producers had significantly higher average pairwise turnover and total beta diversity than carnivores. Main conclusions The present results provide evidence that species turnover, being consistently the larger component of total beta diversity, and nestedness are related to the latitude of the study area and intrinsic organismal features. We showed that two beta-diversity components had generally opposing patterns with regard to latitude. We highlight that beta-diversity partition may give additional insights into the underlying causes of spatial variability in biotic communities compared with total beta diversity alone.

The ecological role of ponds in a changing world

Abstract: The fifth conference of the European Pond Conservation Network (Luxembourg, June 2012) brought together researchers, environmental managers, and other stakeholders with the aim to share state-of-the-art knowledge on the ecology, management, and conservation of ponds in the context of the many challenges facing the wider water environment. Although well-known ecological patterns apply to most ponds in Europe and elsewhere, recent data highlight that part of the environmental variables governing pond biodiversity remain specific to climatic/biogeographic regions and to elevation ranges, suggesting that, in addition to common practice, management plans should include range-specific measures. Beyond the contribution of individual ponds to the aquatic and terrestrial life, connected networks of ponds are vital in the provision of new climate space as a response to global climate change, by allowing the observed northward and/or upward movements of species. In terms of services, ponds offer sustainable solutions to key issues of water management and climate change such as nutrient retention, rainfall interception, or carbon sequestration. While the ecological role of ponds is now well-established, authoritative research-based advice remains needed to inform future direction in the conservation of small water bodies and to further bridge the gap between science and practice.

Mountain lakes: Eyes on global environmental change

Abstract: Mountain lakes are often situated in protected natural areas, a feature that leads to their role as sentinels of global environmental change. Despite variations in latitude, mountain lakes share many features, including their location in catchments with steep topographic gradients, cold temperatures, high incident solar and ultraviolet radiation (UVR), and prolonged ice and snow cover. These characteristics, in turn, affect mountain lake ecosystem structure, diversity, and productivity. The lakes themselves are mostly small, and up until recently, have been characterized as oligotrophic. This paper provides a review and update of the growing body of research that shows that sediments in remote mountain lakes archive regional and global environmental changes, including those linked to climate change, altered biogeochemical cycles, and changes in dust composition and deposition, atmospheric fertilization, and biological manipulations. These archives provide an important record of global environmental change that pre-dates typical monitoring windows. Paleolimnological research at strategically selected lakes has increased our knowledge of interactions among multiple stressors and their synergistic effects on lake systems. Lakes from transects across steep climate (i.e., temperature and effective moisture) gradients in mountain regions show how environmental change alters lakes in close proximity, but at differing climate starting points. Such research in particular highlights the impacts of melting glaciers on mountain lakes. The addition of new proxies, including DNA-based techniques and advanced stable isotopic analyses, provides a gateway to addressing novel research questions about global environmental change. Recent advances in remote sensing and continuous, high-frequency, limnological measurements will improve spatial and temporal resolution and help to add records to spatial gaps including tropical and southern latitudes. Mountain lake records provide a unique opportunity for global scale assessments that provide knowledge necessary to protect the Earth system.

DNA metabarcoding of littoral hard-bottom communities: high diversity and database gaps revealed by two molecular markers

Abstract: Biodiversity assessment of marine hard-bottom communities is hindered by the high diversity and size-ranges of the organisms present. We developed a DNA metabarcoding protocol for biodiversity characterization of structurally complex natural marine hard-bottom communities. We used two molecular markers: the "Leray fragment" of mitochondrial cytochrome c oxidase (COI), for which a novel primer set was developed, and the V7 region of the nuclear small subunit ribosomal RNA (18S). Eight different shallow marine littoral communities from two National Parks in Spain (one in the Atlantic Ocean and another in the Mediterranean Sea) were studied. Samples were sieved into three size fractions from where DNA was extracted separately. Bayesian clustering was used for delimiting molecular operational taxonomic units (MOTUs) and custom reference databases were constructed for taxonomic assignment. Despite applying stringent filters, we found high values for MOTU richness (2,510 and 9,679 MOTUs with 18S and COI, respectively), suggesting that these communities host a large amount of yet undescribed eukaryotic biodiversity. Significant gaps are still found in sequence reference databases, which currently prevent the complete taxonomic assignment of the detected sequences. In our dataset, 85% of 18S MOTUs and 64% of COI MOTUs could be identified to phylum or lower taxonomic level. Nevertheless, those unassigned were mostly rare MOTUs with low numbers of reads, and assigned MOTUs comprised over 90% of the total sequence reads. The identification rate might be significantly improved in the future, as reference databases are further completed. Our results show that marine metabarcoding, currently applied mostly to plankton or sediments, can be adapted to structurally complex hard bottom samples. Thus, eukaryotic metabarcoding emerges as a robust, fast, objective and affordable method to comprehensively characterize the diversity of marine benthic communities dominated by macroscopic seaweeds and colonial or modular sessile metazoans. The 18S marker lacks species-level resolution and thus cannot be recommended to assess the detailed taxonomic composition of these communities. Our new universal primers for COI can potentially be used for biodiversity assessment with high taxonomic resolution in a wide array of marine, terrestrial or freshwater eukaryotic communities.

Translating Regime Shifts in Shallow Lakes into Changes in Ecosystem Functions and Services

Abstract: Shallow lakes, the most prevalent type of freshwater ecosystems, can shift between clear states with macrophyte dominance and turbid, phytoplankton-dominated states. Such transformations, commonly termed regime shifts, have gained increasing attention in recent decades. Of 1084 studies documenting regime shifts, only 28% investigated the consequences for ecosystem functions and services such as habitat (13%), carbon processing (4%), or nutrient retention (4%). Although there is general consensus that a clear macrophyte state supports a higher diversity of aquatic organisms than a turbid one, the effects of shifts on primary production, carbon burial, greenhouse-gas emissions, and nutrient retention remain ambiguous. Shifts between the two states also affect drinking-water quality and the recreational value of lakes, leading to conflicting management measures and potentially deteriorating natural functions. We call for more comprehensive studies on the effects of regime shifts on ecosystem functions in shallow lakes to guide their sustainable management.