Maria Alp | Inra - Academia.edu (original) (raw)

Papers by Maria Alp

Ecosystems, 2020

Productive and ecologically highly valuable ecosystems, macrotidal estuaries are also characteris... more Productive and ecologically highly valuable ecosystems, macrotidal estuaries are also characterised by complex habitat and connectivity dynamics driven by tidal and freshwater influence. Organisms living in these constantly changing systems have to match their movement patterns to the shifting habitat mosaic using available windows of connectivity to access habitat patches of interest. This appears particularly important for the juvenile stages of many fish species colonising shallow and intertidal areas of the estuaries as summer nurseries. We apply tools from landscape ecology to investigate the estuarine habitat and connectivity dynamics on the example of juvenile seabass (Dicentrarchus labrax). We test, under which conditions spatio-temporal bottlenecks to estuarine nursery colonisation may emerge for this species in a human-modified estuary. Combining a hydrodynamic model of the Seine estuary with remote-sensing data allows us to capture structural changes in habitat availability and connectivity at the estuarine scale and at a fine spatio-temporal resolution. With chronological least-cost modelling of successive tidal steps, we assess patterns of nursery accessibility and estimate tidal colonisation fronts for different mobility scenarios. We show that, at certain hydrological conditions, tidal water level variation causes local disruptions of habitat availability and connectivity, creating temporary bottlenecks for seabass juveniles' movement. Fish mobility appears determinant for their vulnerability to these connectivity disruptions. Our approach allows for quantitative assessment and visualisation of riverscape complexity related to tidal dynamics. It is applicable to other highly dynamic ecosystems, where the mobile nature of connectivity and habitats needs to be integrated into conservation and management planning.

River Research and Applications

ABSTRACT Die verschiedenen Abschnitte eines Fliessgewässers sind Teile eines Ganzen und beein!uss... more ABSTRACT Die verschiedenen Abschnitte eines Fliessgewässers sind Teile eines Ganzen und beein!ussen sich gegenseitig. Kenntnisse über die Vernetzung sind Voraussetzung dafür, lokale und regionale Prozesse in Fliessgewässern zu verstehen. Wie diese bei einer Revitalisierung am besten berücksichtigt werden können, zeigt das vorliegende Merkblatt.

Zusammenfassung Die funktionelle Vernetzung von Flussgebieten spielt eine wichtige Rolle fur aqua... more Zusammenfassung Die funktionelle Vernetzung von Flussgebieten spielt eine wichtige Rolle fur aquatische und terrestrische Lebensgemeinschaften. Sie erlaubt eine Besiedlung der Habitate, den genetischen Austausch zwischen Populationen und fuhrt zu einer zeitlichen Verknupfung der Lebensraume zu unterschiedlichen Jahreszeiten, Tageszeiten oder Lebensphasen. Die strukturelle Vernetzung von Lebensraumen kann mit Erhebungen zur Okomorphologie des Fliessgewassers und einer Analyse des Vorhandenseins von kunstlichen Barrieren erhoben werden. Der Grad der funktionellen Vernetzung kann mit drei Methoden quantifiziert werden – Fang markierter Individuen, Radiotelemetrie, oder mit Daten von genetischen Markern. Verschiedene Populationsmodelle beschreiben die Populationsstruktur und den genetischen Austausch zwischen Populationen am Fliessgewasser. Insbesondere bei Metapopulationen und raumlich strukturierten Populationen muss darauf geachtet werden, dass die einzelnen Flussabschnitte gut verne...

Biodiversitat ist eine grundlegende Eigenschaft natUrlicher Dkosysteme, die durch zunehmende mens... more Biodiversitat ist eine grundlegende Eigenschaft natUrlicher Dkosysteme, die durch zunehmende menschliche Eingriffe in den letzten Jahrhunderten stark bedroht ist. Der komplexe Begriff Biodiversitat umfasst die Vielfalt an Lebensraumen und Arten mit ihren 6kologischen Funktionen und Interaktionen und ihrer genetischen Vielfalt. AI/ diese Aspekte sind eng miteinander verknupft, und ein sachkundiges Wissen uber diese Zusammenhange ist eine wichtige Voraussetzung fur die effiziente Planung von Massnahmen zur Erhaltung und zur F6rderung der Biodiversitat. Dieser Artikel erlautert wichtige Aspekte der Biodiversitat in Fliessgewassern. Unter anderem werden Ergebnisse von vier ausgewahlten Studien vorgestellt, die sich im Rahmen des Projekts «Integrales Flussgebietsmanagement" mit verschiedenen Aspekten derBiodiversitat befassthaben. Wie hangtdie Vielfalt aquatischerOrganismen mit der Flussmorphologiezusammen? Wie k6nnen die Anspruche verschiedener Lebensphasen bei aquatischen Organism...

Annual Review of Ecology, Evolution, and Systematics

Understanding what regulates population sizes of organisms with complex life cycles is challengin... more Understanding what regulates population sizes of organisms with complex life cycles is challenging because limits on population sizes can occur at any stage or transition. We extend a conceptual framework to explore whether numbers of successfully laid eggs determine densities of later stages in insects, fish, amphibians, and snails inhabiting marine, freshwater, or terrestrial habitats. Our review suggests novel hypotheses, which propose characteristics of species or environments that create spatial variation in egg densities and predict when such patterns are maintained throughout subsequent life-cycle stages. Existing data, although limited, suggest that persistent, strong associations between egg and subsequent juvenile densities are likely for species where suitable egg-laying habitat is in short supply. Those associations are weakened in some environments and for some species by density-dependent losses of eggs or hatchlings. Such cross-ecosystem comparisons are fundamental to...

Merkblatt Sammlung Wasserbau Und Okologie, Oct 15, 2012

Scientific Data

Dispersal is an essential process in population and community dynamics, but is difficult to measu... more Dispersal is an essential process in population and community dynamics, but is difficult to measure in the field. In freshwater ecosystems, information on biological traits related to organisms’ morphology, life history and behaviour provides useful dispersal proxies, but information remains scattered or unpublished for many taxa. We compiled information on multiple dispersal-related biological traits of European aquatic macroinvertebrates in a unique resource, the DISPERSE database. DISPERSE includes nine dispersal-related traits subdivided into 39 trait categories for 480 taxa, including Annelida, Mollusca, Platyhelminthes, and Arthropoda such as Crustacea and Insecta, generally at the genus level. Information within DISPERSE can be used to address fundamental research questions in metapopulation ecology, metacommunity ecology, macroecology and evolutionary ecology. Information on dispersal proxies can be applied to improve predictions of ecological responses to global change, and...

Getting from Sea to Nurseries: Considering Tidal Dynamics of Juvenile Habitat Distribution and Connectivity in a Highly Modified Estuarine Riverscape, 2020

Productive and ecologically highly valuable ecosystems, macrotidal estuaries are also characteris... more Productive and ecologically highly valuable ecosystems, macrotidal estuaries are also characterised by complex habitat and connectivity dynamics driven by tidal and freshwater influence. Organisms living in these constantly changing systems have to match their movement patterns to the shifting habitat mosaic using available windows of connectivity to access habitat patches of interest. This appears particularly important for the juvenile stages of many fish species colonising shallow and intertidal areas of the estuaries as summer nurseries. We apply tools from landscape ecology to investigate the estuarine habitat and connectivity dynamics on the example of juvenile seabass (Dicentrarchus labrax). We test under which conditions spatio-temporal bottlenecks to estuarine nursery colonisation may emerge for this species in a human-modified estuary. Combining a hydrodynamic model of the Seine estuary with remote sensing data allows us to capture structural changes in habitat availability and connectivity at the estuarine scale and at a fine spatio-temporal resolution. With chronological least-cost modelling of successive tidal steps, we assess patterns of nursery accessibility and estimate tidal colonisation fronts for different mobility scenarios. We show that, at certain hydrological conditions, tidal water level variation causes local disruptions of habitat availability and connectivity, creating temporary bottlenecks for seabass juveniles’ movement. Fish mobility appears determinant for their vulnerability to these connectivity disruptions. Our approach allows for quantitative assessment and visualisation of riverscape complexity related to tidal dynamics. It is applicable to other highly dynamic ecosystems, where the mobile nature of connectivity and habitats needs to be integrated into conservation and management planning.

Efficient monitoring tools for the assessment of stream ecosystem response to urbanization and ag... more Efficient monitoring tools for the assessment of stream ecosystem response to urbanization and agricultural land use are urgently needed but still lacking in West Africa. This study investigated taxonomic and functional composition of macroinver-tebrate communities at 29 sites, each exhibiting one of four disturbance levels ['protected' (P), 'extensive agriculture', 'intensive agriculture' (IA) and 'urban' (U)] in Burkina Faso and explored their potential for bioassessment. We recorded a total of 100 taxa belonging to 58 families, with the highest richness (16.9 taxa per site) observed in the sites with IA and lowest (3.4 taxa) in U sites. We found a gradual decrease of sensitive Ephemeroptera, Plecoptera and Trichoptera taxa and of collector-filterers feeding guild between P, agricultural and U sites accompanied by an increase in the relative abundance of tolerant dipteran taxa. Measures of overall taxonomic richness and diversity were mostly efficient in detecting the high impoverishment of the U sites, while FFG ratios did not deliver consistent results. Finally, all four land use types were successfully distinguished by identifying indicator taxa through hierarchical clustering and indicator value index. This work produced an unprecedented faunal inventory of Burkina Faso streams and laid the basis for the development of urgently needed stream assessment tools.

Ecology letters, Jan 2, 2016

Although climate warming has been widely demonstrated to induce shifts in the timing of many biol... more Although climate warming has been widely demonstrated to induce shifts in the timing of many biological events, the phenological consequences of other prominent global change drivers remain largely unknown. Here, we investigated the effects of biological invasions on the seasonality of leaf litter decomposition, a crucial freshwater ecosystem function. Decomposition rates were quantified in 18 temperate shallow lakes distributed along a gradient of crayfish invasion and a temperature-based model was constructed to predict yearly patterns of decomposition. We found that, through direct detritus consumption, omnivorous invasive crayfish accelerated decomposition rates up to fivefold in spring, enhancing temperature dependence of the process and shortening the period of major detritus availability in the ecosystem by up to 39 days (95% CI: 15-61). The fact that our estimates are an order of magnitude higher than any previously reported climate-driven phenological shifts indicates that ...

Your article is protected by copyright and all rights are held exclusively by The Japanese Societ... more Your article is protected by copyright and all rights are held exclusively by The Japanese Society of Limnology. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".

Freshwater Biology, 2014

1. Molecular genetic techniques have been used in freshwater biology for more than 30 years. Earl... more 1. Molecular genetic techniques have been used in freshwater biology for more than 30 years. Early work focussed on studies of population structure, systematics and taxonomy. More recently, the range of studies has broadened to include ecology and adaptation. Advances in analytical methods and in technology (e.g. next-generation sequencing) and decreasing costs of data production ensure that the field will continue to develop and broaden in scope. 2. At least three factors make the application of molecular techniques to freshwater biology exciting. First, the highly variable nature of many aquatic habitats makes them excellent models for the study of environmental change on ecological and evolutionary time scales. Second, the mature state of the field of freshwater biology provides an extensive foundation of ecological knowledge of freshwater organisms and their distinct adaptations. Third, the methodological advances allow researchers to focus more on merging molecular and ecological research and less on designing studies around technical limitations. 3. We identified eight research areas in freshwater biology in which the integration of molecular and ecological approaches provides exceptional opportunities. The list is not exhaustive, but considers a broad range of topics and spans the continuum from basic to applied research. The areas identified use a combination of natural, experimental and in silico approaches. 4. With advancing molecular techniques, freshwater biology is in an unusually strong position to link the genetic basis and ecological importance of adaptations across a wide range of taxa, ecosystems and spatiotemporal scales. Our aim was to identify opportunities for the integration of molecular and ecological approaches, to motivate greater collaboration and crossover, and to promote exploitation of the synergies of bridging ecological and evolutionary freshwater research.

Freshwater Biology, 2013

ABSTRACT 1. Many streams today have modified channels, substratum composition, flows and temperat... more ABSTRACT 1. Many streams today have modified channels, substratum composition, flows and temperature regimes. Understanding how these potential stressors affect key processes governing populations is crucial towards counteracting species decline and loss. For aquatic organisms with complex life cycles that include a terrestrial adult stage, successful reproduction involving a transition from the terrestrial to aquatic environment for oviposition can be an important constraint. 2. Our main goal was to test for the effects of local stream degradation on egg mass densities of macroinvertebrates with different requirements for oviposition habitat. We experimentally manipulated oviposition substrate availability in two Swiss gravel-bed rivers by adding bricks to stream beds of channelised, restored and near natural reaches differing in their depth profile and availability of large rocks. We followed oviposition on bricks and natural rocks between May and October 2008 and quantified egg mass densities of two aquatic insects with a terrestrial stage (Baetis spp. and Hydropsyche spp.) and an entirely aquatic leech Erpobdella octoculata. Individual and interactive effects of mean water depth fluctuations, depth variability, frequency of large rocks and temperature on egg mass densities were evaluated using a model selection approach. 3. Response to our manipulation in terms of relative use of bricks for oviposition was strongest in the two insect taxa, whose egg mass densities responded to the presence of large substrata in study reaches. We also found evidence for a weak water level effect on egg mass densities of Baetis, a mayfly that uses protruding rocks for oviposition, in contrast to Hydropsyche, which apparently is capable of diving. While no clear response to our manipulation was found in Erpobdella octoculata, its overall cocoon densities were influenced by the variability of depth profile and increased in reaches with lower streambed heterogeneity. 4. Our results suggest that stream degradation has high potential to constrain reproduction of many species, in particular those with complex life cycles such as aquatic insects. Investigation in modified riverscapes of the specific effects of different constraints to recruitment processes is a prerequisite for successful management and conservation.

Efficient monitoring tools for the assessment of stream ecosystem response to urbanization and ag... more Efficient monitoring tools for the assessment of stream ecosystem response to urbanization and agricultural land use are urgently needed but still lacking in West Africa. This study investigated taxonomic and functional composition of macroinvertebrate communities at 29 sites, each exhibiting one of four disturbance levels [‘protected’ (P), ‘extensive agriculture’, ‘intensive agriculture’ (IA) and ‘urban’ (U)] in Burkina Faso and explored their potential for bioassessment. We recorded a total of 100 taxa belonging to 58 families, with the highest richness (16.9 taxa per site) observed in the sites with IA and lowest (3.4 taxa) in U sites. We found a gradual decrease of sensitive Ephemeroptera, Plecoptera and Trichoptera taxa and of collector-filterers feeding guild between P, agricultural and U sites accompanied by an increase in the relative abundance of tolerant dipteran taxa. Measures of overall taxonomic richness and diversity were mostly efficient in detecting the high impoverishment of the U sites, while FFG ratios did not deliver consistent results. Finally, all four land use types were successfully distinguished by identifying indicator taxa through hierarchical clustering and indicator value index. This work produced an unprecedented faunal inventory of Burkina Faso streams and laid the basis for the development of urgently needed stream assessment tools.

Aquatic Sciences, 2013

Stable isotopes ( 13 C and 15 N) are widely applied in studies of trophic links. We used this met... more Stable isotopes ( 13 C and 15 N) are widely applied in studies of trophic links. We used this method to investigate the contribution of aquatic and terrestrial prey to the diet of riparian predatory arthropods in two mountain headwater streams in Colorado, USA. Aquatic and terrestrial prey and riparian predators were collected during summer 2009. To evaluate the reliability of conclusions based on stable isotope ratios, we compared the isotopic signatures of aquatic larval and terrestrial adult stages of three abundant stream insect species and assessed variation in mixing model estimates for spider diet composition under varying assumptions for trophic fractionation. Adult isotopic signatures of some aquatic prey species were indistinguishable from those of prey species with exclusively terrestrial life histories (stoneflies: 13 C and 15 N, chironomids: 13 C). Other prey had distinctly aquatic isotopic signatures as both larvae and adults (a mayfly and a caddisfly). There was no evidence that prey with aquatic isotopic signatures contributed to the diet of the spiders near one stream. For the other stream, mixing model analysis suggested that chironomids were included in the diets of lycosid, linyphiid and liocranid spiders. Reliable estimates of the contributions of prey sources were compromised by the sensitivity of mixing models to assumptions on trophic fractionation and the presence of ''isotopically cryptic'' prey. This study emphasizes the importance of supporting isotope-based studies on crossboundary trophic links with data on isotopic shifts in prey with complex life cycles and assessment of fractionation rates specific to the study system.

Hydrobiologia, 2013

We present a new hydro-morphological index of diversity (HMID), a tool aimed for use in river eng... more We present a new hydro-morphological index of diversity (HMID), a tool aimed for use in river engineering projects and firstly developed at gravel-bed streams in Switzerland, but intended for a broader use. We carried out field work with extensive hydraulic and geomorphic data collection, conducted correlation analysis with hydro-morphological variables, formulated the HMID, and analyzed the correlation between HMID and a visual habitat assessment method. The HMID is calculated by means of the coefficient of variation of the hydraulic variables flow velocity and water depth, which have been demonstrated to sufficiently represent the hydro-morphological heterogeneity of alpine gravel-bed stream reaches.

Ecosystems, 2020

River Research and Applications

Annual Review of Ecology, Evolution, and Systematics

Merkblatt Sammlung Wasserbau Und Okologie, Oct 15, 2012

Scientific Data

Getting from Sea to Nurseries: Considering Tidal Dynamics of Juvenile Habitat Distribution and Connectivity in a Highly Modified Estuarine Riverscape, 2020

Productive and ecologically highly valuable ecosystems, macrotidal estuaries are also characteris... more Productive and ecologically highly valuable ecosystems, macrotidal estuaries are also characterised by complex habitat and connectivity dynamics driven by tidal and freshwater influence. Organisms living in these constantly changing systems have to match their movement patterns to the shifting habitat mosaic using available windows of connectivity to access habitat patches of interest. This appears particularly important for the juvenile stages of many fish species colonising shallow and intertidal areas of the estuaries as summer nurseries. We apply tools from landscape ecology to investigate the estuarine habitat and connectivity dynamics on the example of juvenile seabass (Dicentrarchus labrax). We test under which conditions spatio-temporal bottlenecks to estuarine nursery colonisation may emerge for this species in a human-modified estuary. Combining a hydrodynamic model of the Seine estuary with remote sensing data allows us to capture structural changes in habitat availability and connectivity at the estuarine scale and at a fine spatio-temporal resolution. With chronological least-cost modelling of successive tidal steps, we assess patterns of nursery accessibility and estimate tidal colonisation fronts for different mobility scenarios. We show that, at certain hydrological conditions, tidal water level variation causes local disruptions of habitat availability and connectivity, creating temporary bottlenecks for seabass juveniles’ movement. Fish mobility appears determinant for their vulnerability to these connectivity disruptions. Our approach allows for quantitative assessment and visualisation of riverscape complexity related to tidal dynamics. It is applicable to other highly dynamic ecosystems, where the mobile nature of connectivity and habitats needs to be integrated into conservation and management planning.

Ecology letters, Jan 2, 2016

Freshwater Biology, 2014

Freshwater Biology, 2013

Efficient monitoring tools for the assessment of stream ecosystem response to urbanization and ag... more Efficient monitoring tools for the assessment of stream ecosystem response to urbanization and agricultural land use are urgently needed but still lacking in West Africa. This study investigated taxonomic and functional composition of macroinvertebrate communities at 29 sites, each exhibiting one of four disturbance levels [‘protected’ (P), ‘extensive agriculture’, ‘intensive agriculture’ (IA) and ‘urban’ (U)] in Burkina Faso and explored their potential for bioassessment. We recorded a total of 100 taxa belonging to 58 families, with the highest richness (16.9 taxa per site) observed in the sites with IA and lowest (3.4 taxa) in U sites. We found a gradual decrease of sensitive Ephemeroptera, Plecoptera and Trichoptera taxa and of collector-filterers feeding guild between P, agricultural and U sites accompanied by an increase in the relative abundance of tolerant dipteran taxa. Measures of overall taxonomic richness and diversity were mostly efficient in detecting the high impoverishment of the U sites, while FFG ratios did not deliver consistent results. Finally, all four land use types were successfully distinguished by identifying indicator taxa through hierarchical clustering and indicator value index. This work produced an unprecedented faunal inventory of Burkina Faso streams and laid the basis for the development of urgently needed stream assessment tools.

Aquatic Sciences, 2013

Hydrobiologia, 2013