Search

Coastal ecosystems dominate oceanic methane (CH4) emissions. However, there is limited knowledge about how biotic interactions between infauna and aerobic methanotrophs (i.e. CH4 oxidizing bacteria) drive the spatial–temporal dynamics of these emissions. Here, we investigated the role of meio- and macrofauna in mediating CH4 sediment–water fluxes and aerobic methanotrophic activity that can oxidize significant portions of CH4. We show that macrofauna increases CH4 fluxes by enhancing vertical solute transport through bioturbation, but this effect is somewhat offset by high meiofauna abundance. The increase in CH4 flux reduces CH4 pore-water availability, resulting in lower abundance and activity of aerobic methanotrophs, an effect that counterbalances the potential stimulation of these bacteria by higher oxygen flux to the sediment via bioturbation. These findings indicate that a larger than previously thought portion of CH4 emissions from coastal ecosystems is due to faunal activity and multiple complex interactions with methanotrophs.

Fishing-down-marine-food-webs has resulted in alarming declines of various species worldwide. Benthic rays are one examples of such overexploited species. On tidal flats, these rays are highly abundant and play an ecologically important role. They use tidal flats as refuge, feeding and resting grounds, during which they bury into the sediment, which results in sediment bioturbation. Changes in bioturbation intensity, following ray removal, may affect the biogeomorphology of tidal flats with possible cascading effects on the macrozoobenthic community. However, it is poorly understood how these indirect effects could influence ecosystem function. We therefore studied the geomorphic impact of benthic rays (specifically the pearl whipray/stingray Fontitrygon margaritella) on the tropical tidal flats of the Bijagós Archipelago, Guinea-Bissau, on a landscape scale. We investigated 1) bioturbation rates by rays using drone and ground surveys, 2) the spatial distribution of ray pits on multiple tidal flats, 3) the impact of rays on sediment properties and macrozoobenthos by experimental exclusion (15 months). Benthic rays bioturbated 3.7 ± 0.35% of the tidal flat’s sediment surface per day over one single 24-h period, which equals a complete top-sediment-surface turnover every 27 days. The spatial distribution of ray pits was affected by tidal flat geomorphology since pits decayed faster at areas exposed to strong hydrodynamic forces. Predator exclusion altered sediment properties, leading to changes in sedimentation (− 17%) and erosion (− 43%) rates. In addition, macrozoobenthic species composition changed, marked by an increase in Capitellidae worms and a greater biomass of Malacostraca over time. These changes indicated substantial effects of ray bioturbation on the biotic and geomorphic landscape of tidal flats. Overall, we conclude that changing abundances of benthic rays can have clear landscape-wide geomorphological effects on intertidal ecosystems. These indirect co

Fishing-down-marine-food-webs has resulted in alarming declines of various species worldwide. Benthic rays are one examples of such overexploited species. On tidal flats, these rays are highly abundant and play an ecologically important role. They use tidal flats as refuge, feeding and resting grounds, during which they bury into the sediment, which results in sediment bioturbation. Changes in bioturbation intensity, following ray removal, may affect the biogeomorphology of tidal flats with possible cascading effects on the macrozoobenthic community. However, it is poorly understood how these indirect effects could influence ecosystem function. We therefore studied the geomorphic impact of benthic rays (specifically the pearl whipray/stingray Fontitrygon margaritella) on the tropical tidal flats of the Bijagós Archipelago, Guinea-Bissau, on a landscape scale. We investigated 1) bioturbation rates by rays using drone and ground surveys, 2) the spatial distribution of ray pits on multiple tidal flats, 3) the impact of rays on sediment properties and macrozoobenthos by experimental exclusion (15 months). Benthic rays bioturbated 3.7 ± 0.35% of the tidal flat’s sediment surface per day over one single 24-h period, which equals a complete top-sediment-surface turnover every 27 days. The spatial distribution of ray pits was affected by tidal flat geomorphology since pits decayed faster at areas exposed to strong hydrodynamic forces. Predator exclusion altered sediment properties, leading to changes in sedimentation (− 17%) and erosion (− 43%) rates. In addition, macrozoobenthic species composition changed, marked by an increase in Capitellidae worms and a greater biomass of Malacostraca over time. These changes indicated substantial effects of ray bioturbation on the biotic and geomorphic landscape of tidal flats. Overall, we conclude that changing abundances of benthic rays can have clear landscape-wide geomorphological effects on intertidal ecosystems. These indirect co

Ambitious to fulfill the European Water Framework Directive obligations, the European governments support projects to rehabilitate lakes with poor water quality. However, most lake restorations having relied on biomanipulation by fish thinning have failed to improve or even maintain water quality. Previous attempts removed all target fish species simultaneously, thus making it impossible to assess the specific impact of each feeding group on water chemistry. Lake Bromme was selected for extensive, time-selective fish biomanipulation to improve water clarity and promote submerged macrophytes and piscivorous fish stocks over a three-year monitoring period. Thinning of adult benthivorous bream (Abramis brama) and tench (Tinca tinca) was conducted throughout year one while thinning in years two and three targeted planktivorous roach (Rutilus rutilus), juvenile bream, and small perch (Perca fluviatilis). Yearly fish surveys assessed changes in fish population structure and biomass. Water quality parameters were monitored continually, and the cover of submerged macrophytes was surveyed annually via sonar. We found no improvement in water clarity or reductions of nutrients, organic particles, chlorophyll concentrations, or watercolor, despite a 6-fold thinning of total estimated fish biomass, from 112 to 19 kg ha−1. Over the period, the macrophyte cover increased from 0.8 to 13.5 %, but no recruitment of large piscivorous fish (perch and pike (Esox lucius) > 10 cm) was detected. We found higher correlations of particle concentration and water clarity to water temperature than to wind speed, which indicates sediment particle resuspension by the remaining fish community (mostly carp Cyprinus carpio) that forage on benthos in shallow lakes. Further system-ecological research in Lake Bromme should evaluate whether thinning the stock of carp and increasing plant cover may improve water quality and test which optical properties sustain high water turbidity and prevent shallow, Ambitious to fulfill the European Water Framework Directive obligations, the European governments support projects to rehabilitate lakes with poor water quality. However, most lake restorations having relied on biomanipulation by fish thinning have failed to improve or even maintain water quality. Previous attempts removed all target fish species simultaneously, thus making it impossible to assess the specific impact of each feeding group on water chemistry. Lake Bromme was selected for extensive, time-selective fish biomanipulation to improve water clarity and promote submerged macrophytes and piscivorous fish stocks over a three-year monitoring period. Thinning of adult benthivorous bream (Abramis brama) and tench (Tinca tinca) was conducted throughout year one while thinning in years two and three targeted planktivorous roach (Rutilus rutilus), juvenile bream, and small perch (Perca fluviatilis). Yearly fish surveys assessed changes in fish population structure and biomass. Water quality parameters were monitored continually, and the cover of submerged macrophytes was surveyed annually via sonar. We found no improvement in water clarity or reductions of nutrients, organic particles, chlorophyll concentrations, or watercolor, despite a 6-fold thinning of total estimated fish biomass, from 112 to 19 kg ha−1. Over the period, the macrophyte cover increased from 0.8 to 13.5 %, but no recruitment of large piscivorous fish (perch and pike (Esox lucius) > 10 cm) was detected. We found higher correlations of particle concentration and water clarity to water temperature than to wind speed, which indicates sediment particle resuspension by the remaining fish community (mostly carp Cyprinus carpio) that forage on benthos in shallow lakes. Further system-ecological research in Lake Bromme should evaluate whether thinning the stock of carp and increasing plant cover may improve water quality and test which optical properties sustain high water turbidity and prevent shallow

Ambitious to fulfill the European Water Framework Directive obligations, the European governments support projects to rehabilitate lakes with poor water quality. However, most lake restorations having relied on biomanipulation by fish thinning have failed to improve or even maintain water quality. Previous attempts removed all target fish species simultaneously, thus making it impossible to assess the specific impact of each feeding group on water chemistry. Lake Bromme was selected for extensive, time-selective fish biomanipulation to improve water clarity and promote submerged macrophytes and piscivorous fish stocks over a three-year monitoring period. Thinning of adult benthivorous bream (Abramis brama) and tench (Tinca tinca) was conducted throughout year one while thinning in years two and three targeted planktivorous roach (Rutilus rutilus), juvenile bream, and small perch (Perca fluviatilis). Yearly fish surveys assessed changes in fish population structure and biomass. Water quality parameters were monitored continually, and the cover of submerged macrophytes was surveyed annually via sonar. We found no improvement in water clarity or reductions of nutrients, organic particles, chlorophyll concentrations, or watercolor, despite a 6-fold thinning of total estimated fish biomass, from 112 to 19 kg ha−1. Over the period, the macrophyte cover increased from 0.8 to 13.5 %, but no recruitment of large piscivorous fish (perch and pike (Esox lucius) > 10 cm) was detected. We found higher correlations of particle concentration and water clarity to water temperature than to wind speed, which indicates sediment particle resuspension by the remaining fish community (mostly carp Cyprinus carpio) that forage on benthos in shallow lakes. Further system-ecological research in Lake Bromme should evaluate whether thinning the stock of carp and increasing plant cover may improve water quality and test which optical properties sustain high water turbidity and prevent shallow, Ambitious to fulfill the European Water Framework Directive obligations, the European governments support projects to rehabilitate lakes with poor water quality. However, most lake restorations having relied on biomanipulation by fish thinning have failed to improve or even maintain water quality. Previous attempts removed all target fish species simultaneously, thus making it impossible to assess the specific impact of each feeding group on water chemistry. Lake Bromme was selected for extensive, time-selective fish biomanipulation to improve water clarity and promote submerged macrophytes and piscivorous fish stocks over a three-year monitoring period. Thinning of adult benthivorous bream (Abramis brama) and tench (Tinca tinca) was conducted throughout year one while thinning in years two and three targeted planktivorous roach (Rutilus rutilus), juvenile bream, and small perch (Perca fluviatilis). Yearly fish surveys assessed changes in fish population structure and biomass. Water quality parameters were monitored continually, and the cover of submerged macrophytes was surveyed annually via sonar. We found no improvement in water clarity or reductions of nutrients, organic particles, chlorophyll concentrations, or watercolor, despite a 6-fold thinning of total estimated fish biomass, from 112 to 19 kg ha−1. Over the period, the macrophyte cover increased from 0.8 to 13.5 %, but no recruitment of large piscivorous fish (perch and pike (Esox lucius) > 10 cm) was detected. We found higher correlations of particle concentration and water clarity to water temperature than to wind speed, which indicates sediment particle resuspension by the remaining fish community (mostly carp Cyprinus carpio) that forage on benthos in shallow lakes. Further system-ecological research in Lake Bromme should evaluate whether thinning the stock of carp and increasing plant cover may improve water quality and test which optical properties sustain high water turbidity and prevent shallow

Understanding the formation of tropical yellow to red earth (TYRE) is essential for preserving soil multifunctionality in well-drained tropical landscapes. Weathering and bioturbation mutually interact in TYRE evolution, whereas allochthonous materials appear restricted to distinct (paleo)landscapes. A layered appearance of TYRE can result from quasi-constant deposition of invertebrate mound debris, outcompeting diffusional mixing. Age-depth profiles from optically stimulated luminescence (OSL) and charcoal radiocarbon (14Cchar) data of TYRE sites in different tropical landscapes, both from the literature and the present study, all reveal quasi-constant soil upbuilding, in accordance with our model. The rates of soil upbuilding are mostly in the range of 100–200 mm*ka−1, which conforms with published mounding rates of termites and ants. By comparison, geochemical transformation of rock to saprolite proceeds at rates at least one order of magnitude smaller. Termites mining saprolite, sometimes even below indurated subsoil, produce TYRE, thus linking the interconnected subsystems of differing process rates. The work of the bioengineers appears essential for transforming the deep-weathering products into well-structured TYRE. Future research may extend the provided database, the spatial scale, and the use of geochronology, coupled with paleoenvironmental proxies, in order to further enhance our understanding of tropical soil and landscape evolution, as one basis for advances in sustainable land use., SCOPUS: re.j, info:eu-repo/semantics/published

In the nineteenth century, numerous settlements were established in the alpine region of Fennoscandia (the Scandes), an area that later became a major international scene for Arctic research. Here we raise awareness of this era and show that earthworm-driven bioturbation in “pristine” soils around contemporary Arctic research infrastructure is caused by soil fauna left behind during early land use. We use soil preserved under an alpine settlement to highlight that soils were not bioturbated when the first house was built at a site where bioturbation is now widespread. A review of archived material with unique site-specific chronology constrained the onset of bioturbation to the post-1871 era. Our results suggest that small-scale land use introduced earthworms that now thrive far beyond the realms of former cultivated fields. The legacy of soil fauna from this example of “ecological imperialism” still lingers and should be considered when studying soils of the Scandes.

In the nineteenth century, numerous settlements were established in the alpine region of Fennoscandia (the Scandes), an area that later became a major international scene for Arctic research. Here we raise awareness of this era and show that earthworm-driven bioturbation in “pristine” soils around contemporary Arctic research infrastructure is caused by soil fauna left behind during early land use. We use soil preserved under an alpine settlement to highlight that soils were not bioturbated when the first house was built at a site where bioturbation is now widespread. A review of archived material with unique site-specific chronology constrained the onset of bioturbation to the post-1871 era. Our results suggest that small-scale land use introduced earthworms that now thrive far beyond the realms of former cultivated fields. The legacy of soil fauna from this example of “ecological imperialism” still lingers and should be considered when studying soils of the Scandes.

Extreme weather events are increasing in intensity, duration, and frequency, and threatening tidal flat ecosystems due to global climate change. Benthic macrofauna plays essential roles in biogeomorphic feedback as ecosystem engineers, yet they are prone to extreme environmental fluctuations in storms and drying tidal regimes. Moreover, modern globalization has accelerated the invasion of introduced species, which compete with native species for natural resources. Therefore, studying how benthic macrofauna responds to climate-change-induced extreme weather events may convey an essential message on short-term equilibrium and the long-term development of tidal flat ecosystems. A mesocosm system was designed and customized in the lab to mimic the heatwaves with contrasting magnitudes and durations on tidal flats. Simulated heatwaves were imposed on the model bioturbator species Cerastoderma edule living in different micro-topographies and sediment types, to study the response of bioturbation activities under thermal stress (Chapters 2 & 3). Besides individual-level response, an in-situ experiment was applied to study the effects of repeated storm events on benthic community structure, using a raking treatment to mimic storm-induced sediment disturbance (Chapter 4). Moreover, the effects of compound extreme weather events on species shift were studied by imposing different salinity settings and heatwave profiles on the native C. edule and an introduced bivalve Ruditapes philippinarum (Chapters 5). Macrobenthos' response on the individual level is categorized into the “fight, flight, or freeze” framework. Bioturbators increase metabolic rates to “fight” against the thermal stress and maintain optimal physiological conditions (Chapters 2); they burrowed deeper during low tide to escape from (“flight”) the thermal stress, thereby causing more sediment mixings (Chapters 2 & 3); they reduce activity and metabolism (“freeze”) to maintain basic physiological functions

The ecological deterioration caused by the continuous and excessive use of synthetic inputs in agriculture has prompted the searchfor environmentally favorable resources for crop production. Many have advocated for the use of soils from termite mounds to improve soil andplant health; therefore, the purpose of this study was to characterize the microbiome multifunctionalities that are important for plant health andgrowth in termite mound soil. The metagenomics of soil from termite mounds revealed taxonomic groups with functional potentials associated withpromoting the growth and health of plants in nutrient-poor, virtually dry environments. Analysis of microorganisms revealed that Proteobacteriadominated the soil of termite colonies, while Actinobacteria ranked second. The predominance of Proteobacteria and Actinobacteria, the well-known antibiotic-producing populations, indicates that the termite mound soil microbiome possesses metabolic resistance to biotic stresses.Functions recognized for diverse proteins and genes unveiled that a multi-functional microbiome carry out numerous metabolic functions includ-ing virulence, disease, defense, aromatic compound and iron metabolism, secondary metabolite synthesis, and stress response. The abundanceof genes in termite mound soils associated with these prominent functions could unquestionably validate the enhancement of plants in abioticand biotically stressed environments. This study reveals opportunities to revisit the multifunctionalities of termite mound soils in order to establisha connection between taxonomic diversity, targeted functions, and genes that could improve plant yield and health in unfavorable soil conditions.

Human introductions have resulted in earthworms establishing in the Arctic, species known to cause cascading ecosystem change. However, few quantitative outdoor experiments have been performed that describe how these soil modifying earthworms are reshaping structures in tundra soils. In this study, we used three-dimensional (3-D) X-ray images of soil cores (approximately 10 cm diameter, 20 cm height, N = 48) to assess how earthworms (Aporrectodea sp. and Lumbricus sp.) affect soil structure and macropore networks in an outdoor mesocosm experiment that lasted four summers. Effects were assessed in both shrub-dominated (heath) and herb-dominated (meadow) tundra. Earthworms almost doubled the macroporosity in meadow soils and tripled macroporosity in heath. Interestingly, the fractal dimension of macropores decreased in response to earthworm burrowing in both systems, indicating that the presence of earthworms reduced the geometric complexity in comparison to other pore-generating processes active in the tundra. Observed effects on soil structure occurred along with a dramatically reduced soil moisture content, which was observed the first winter after earthworm introduction in the meadow. Our findings suggest that predictions of future changes in vegetation and soil carbon pools in the Arctic should include major impacts on soil properties that earthworms induce.

The increasing frequency and intensity of marine heatwaves (MHWs) observed worldwide entails changes in the structure and functioning of ecological communities. While severe and extreme heatwaves often have more destructive effects, the more subtle effects of moderate and strong heatwaves may nevertheless affect ecosystem functioning through complex, context-dependent linkages between different processes. Here we conducted a laboratory experiment to study the effects of repeated short-term, strong MHWs on macrofauna bioturbation and associated solute fluxes as a measure of ecosystem functioning using natural soft-sediment communities from the Baltic Sea. Our results showed changes in both bioturbation and biogeochemical cycling of nutrients following short-term, strong heatwaves, which seemed to contribute to an enhanced degradation of organic matter in the seafloor and an enhanced exchange of solutes across the sediment-water interface as well as increased sediment oxygen consumption. Following changes in these processes, the relative contribution of macrofauna and the environmental context to ecosystem functioning was altered. Our results highlight the potential of even shorter-term, strong MHWs of having system-wide impacts due to changes in the mechanistic process of bioturbation underpinning the biogeochemical cycling of nutrients. This study also highlights the need to measure a wide range of variables for a comprehensive understanding of the changes in functioning under disturbances, such as MHWs.

Bioturbating organisms provide a key function in marine environments and are generally considered ecosystem engineers. Still, our knowledge of bio- turbation activity in the Arctic deep sea remains relatively shallow. In this study the bioturbation of arctic deep sea macrobenthos in the LTER obser- vatory HAUSGARTEN was studied using multiple sampling devices collected with the research icebreaker Polarstern. The thesis yielded the following out- comes: (I) Spatial patterns in the bioturbation activity were detected and four distinct communities could be identified based on the bioturbation activity. (II) Statistically significant relationships between data gained from different sam- pling devices were proven: Bioturbation potential (BPc, giant box corer) and bioactive depth (BAD, sediment profile imagery) showed a positive relation- ship, which opens new possibilities in the assessment of bioturbation activity. (III) Environmental factors gained from sediment profile imagery and multiple corer samples were able to further categorize the spatial differences between the found communities and their respective habitats. The study found bio- turbation activity in the deep sea of Fram Strait to be similar with bioturbation activities calculated for other habitats (e.g, the German and Belgian North Sea and the English Channel). Bioturbation activity in Fram Strait, being vital for carbon sequestration and nutrient fluxes, was found to be carried out by only a few key species. By identifying new key species for bioturbation, this the- sis not only broadened our understanding of important ecosystem processes but also gave vital insights usable in future habitat and species protection. Sediment profile imagery proved to provide fast and only minimal invasive de- tection of important ecosystem functions and could therefore show to be a vital tool in future conservation management in the area., by Maximilian Tim Schrade, BSc, BSc, Masterarbeit Universität Innsbruck 2023

The increasing frequency and intensity of marine heatwaves (MHWs) observed worldwide entails changes in the structure and functioning of ecological communities. While severe and extreme heatwaves often have more destructive effects, the more subtle effects of moderate and strong heatwaves may nevertheless affect ecosystem functioning through complex, context-dependent linkages between different processes. Here we conducted a laboratory experiment to study the effects of repeated short-term, strong MHWs on macrofauna bioturbation and associated solute fluxes as a measure of ecosystem functioning using natural soft-sediment communities from the Baltic Sea. Our results showed changes in both bioturbation and biogeochemical cycling of nutrients following short-term, strong heatwaves, which seemed to contribute to an enhanced degradation of organic matter in the seafloor and an enhanced exchange of solutes across the sediment-water interface as well as increased sediment oxygen consumption. Following changes in these processes, the relative contribution of macrofauna and the environmental context to ecosystem functioning was altered. Our results highlight the potential of even shorter-term, strong MHWs of having system-wide impacts due to changes in the mechanistic process of bioturbation underpinning the biogeochemical cycling of nutrients. This study also highlights the need to measure a wide range of variables for a comprehensive understanding of the changes in functioning under disturbances, such as MHWs.

The paper aims to build seasonal silica budgets in two macrotidal estuaries, the Elorn and Aulne estuaries of the Bay of Brest (North-Western France), based on modeling and measurements, in order to increase our understanding of the silica (Si) cycle at land-sea interfaces. A diagenetic model was developed to quantify benthic Si fluxes, e.g. aSiO2 deposition fluxes that are difficult to assess through direct measurements. Sediment cores were also seasonally sampled at six stations to provide data essential to parametrize and validate the model. Vertical profiles of porosity, burrowing depth, biodiffusive coefficients, concentrations of amorphous silica (aSiO2) and silicic acid (Si(OH)4 and the proportion of reactive aSiO2 were measured. The results show that sites sampled along the Elorn and Aulne estuaries constitute significant net Si deposition areas (1-4.5 mmol Si m-2 d-1), particularly in the upstream during winter and in midstream and downstream during summer. Year round, reprecipitation is negligible (< 3%) while burial accounts for the retention of ~ 30-80% of deposited aSiO2. In winter, burial dominates the benthic Si budget. As surface-integrated benthic Si fluxes are low compared to riverine aSiO2 fluxes, the Si export to coastal waters is high (93%) during winter. In contrast, in summer, burial accounts for 38% of river Si fluxes, and Si(OH)4 flux from the sediment is high as a result of enhanced benthic recycling and bioirrigation. Internal estuarine processes, e.g., benthic and pelagic primary production, dissolution and benthic Si fluxes, surpass river fluxes in magnitude during summer. Overall, we conclude that the Elorn and Aulne macrotidal estuaries are efficient filters of Si, retaining about 4-38% of river Si fluxes, and even 6-67% when accounting for retention in intertidal marshes, but with massive exports occurring during winter floods.

In the nineteenth century, numerous settlements were established in the alpine region of Fennoscandia (the Scandes), an area that later became a major international scene for Arctic research. Here we raise awareness of this era and show that earthworm-driven bioturbation in “pristine” soils around contemporary Arctic research infrastructure is caused by soil fauna left behind during early land use. We use soil preserved under an alpine settlement to highlight that soils were not bioturbated when the first house was built at a site where bioturbation is now widespread. A review of archived material with unique site-specific chronology constrained the onset of bioturbation to the post-1871 era. Our results suggest that small-scale land use introduced earthworms that now thrive far beyond the realms of former cultivated fields. The legacy of soil fauna from this example of “ecological imperialism” still lingers and should be considered when studying soils of the Scandes.

In the nineteenth century, numerous settlements were established in the alpine region of Fennoscandia (the Scandes), an area that later became a major international scene for Arctic research. Here we raise awareness of this era and show that earthworm-driven bioturbation in “pristine” soils around contemporary Arctic research infrastructure is caused by soil fauna left behind during early land use. We use soil preserved under an alpine settlement to highlight that soils were not bioturbated when the first house was built at a site where bioturbation is now widespread. A review of archived material with unique site-specific chronology constrained the onset of bioturbation to the post-1871 era. Our results suggest that small-scale land use introduced earthworms that now thrive far beyond the realms of former cultivated fields. The legacy of soil fauna from this example of “ecological imperialism” still lingers and should be considered when studying soils of the Scandes.

Soil structure is a dynamic property of soils, which refers to temporal changes in the spatial arrangement of pores, organic matter, and minerals. Its turnover, i.e. the irreversible redistribution of soil constituents, determines essential soil functions including carbon storage. Structure turnover times and its response to biotic versus abiotic drivers have never been quantified directly under natural conditions. We used a novel combination of structure labelling with inert garnet particles and X-ray Computed Tomography to determine structure turnover times of two grassland topsoils with either access or exclusion of roots and fauna > 30 µm. Both, abiotic and biotic factors developed soil structure at a site-specific rate towards a dynamic equilibrium, at which bulk properties remain constant because creation and destruction of structural properties are in balance. Its turnover, however, was mainly determined by macrofaunal activity which varied with environmental conditions. Under dry conditions less favorable for bioturbation, the extrapolated structure turnover time was 33 ± 3 years, while being 16 ± 1 years under moist conditions. Previous studies on organic matter turnover determined in the vicinity of the experimental site showed similar turnover times for particulate organic matter. The similar turnover times suggest that the accessibility of particulate organic matter to decomposers is closely linked to structure turnover, thus highlighting the intimate nexus between structure evolution and carbon persistence in soil.

This paper aims to provide information about the behavior and diet composition of fiddler crabs. The large percentage of sediments present in the stomach of fiddler crabs proves that fiddler crabs play an important role in aerating the soil, which would help in the growth of mangrove and wetland plants. Observations were done in sandy, muddy, and coralline substrates for four months. Thirty fiddler crabs were collected for laboratory test of their diet composition. Sediments had the highest percentage in the stomach content of the fiddler crabs (60%), followed by chum (25%), and leaf particles (15%). The analysis of the fullness of their stomach showed that it was highly significant (df = 2, MS = 2.09, F = 34.34, p = 0.001). While the fiddler crabs ate all three colors of mangrove leaves, it preferred to forage on yellow leaves (n = 104) followed by the brown leaves (n = 78) and the green leaves (n = 77), proving that nutrient recycling occurs in the mangrove area. The existence of the fiddler crabs contributes to a more stable mangrove ecosystem. In addition, this study is the first assessment of fiddler crabs documented in Mindanao, Philippines. Results of the study can be used as a baseline for the protection of mangrove ecosystem species., Este trabajo tiene como objetivo proporcionar información sobre el comportamiento y la composición de la dieta de los cangrejos violinistas. El gran porcentaje de sedimentos presentes en el estómago de los cangrejos violinistas demuestra que los cangrejos violinistas juegan un papel importante en la aireación del suelo, lo que ayudaría al crecimiento de las plantas de manglares y humedales. Las observaciones se realizaron en sustratos arenosos, fangosos y coralinos durante cuatro meses. Treinta cangrejos violinistas fueron recolectados para estudiar en de laboratorio la composición de su dieta. Los sedimentos tuvieron el porcentaje más alto en el contenido estomacal de los cangrejos violinistas (60%), seguidos de la carnada (25%) y las partículas de hojas (15%). El nivel de llenado del estómago mostró que era altamente significativo (df = 2, MS = 2,09, F = 34,34, p = 0,001). Si bien los cangrejos violinistas comieron los tres colores de las hojas de mangle, prefirieron alimentarse de las hojas amarillas (n = 104), seguidas de las hojas marrones (n = 78) y las hojas verdes (n = 77), lo que demuestra que el reciclaje de nutrientes ocurre en la zona de manglares. Los cangrejos violinistas contribuyen a mantener un ecosistema de manglar más estable. Además, este estudio representa la primera evaluación de cangrejos violinistas documentada en Mindanao, Filipinas. Los resultados se pueden utilizar como referencia para la protección de las especies del ecosistema de manglares.

This dataset contains data collected from field experiments studying the use of bioturbation mound as a niche for invasive seagrass settlement and growth, as well as for competition between invasive seagrass and upside-down jellyfish in the Dutch Caribbean. The experimental data describes how many native, invasive and upside-down jellyfish individuals were counted within the in total 20 plots divided over three treatments (natural bioturbation mounds, artificial bioturbation mounds and control vegetated plots) and was collected on the island of Curacao in a 45 day experiment. The transect data describes how the number of invasive seagrass shoots and bioturbation mounds are distributed over a spatial invasion gradient, comparing transect points close to shore (shore) and in the direction towards the center of the bay (inward) and was collected on Bonaire.

Landscapes and ecosystems are the result of two-way interactions between hydro-geomorphic and biological processes. Many animals, particularly those that build structures or transport sediment, are important biogeomorphic agents. Glossosomatidae caddisfly larvae (Insecta, Trichoptera) are globally widespread and abundant inhabitants of gravel-bed rivers. Glossosomatidae build mobile cases from sand that they transport over the river bed. However, there is limited understanding on how Glossosomatidae bioconstructions may influence sand distribution in rivers or how their zoogeomorphic behaviours are influenced by hydraulics or characteristics of the river bed. First, we conducted surveys to quantify the magnitude of sand incorporated into Glossosomatidae (Agapetus fuscipes) cases within a UK river. Second, we studied A. fuscipes movement behaviour and quantified the direction and magnitude of sediment reworking, in a flume, under differing flow velocity and gravel size treatments. We found that 99 % of A. fuscipes larvae transported sediment vertically upwards. This resulted in an average conveyance per larvae of 0.06 g sand upwards by 25 mm (maximum of 50 mm). In gravel beds with a coarse surface layer, this resulted in displacement of sand from sheltered interstices onto the surface of exposed gravel particles. In the flume, this behaviour was maintained even at high flows, sufficient to entrain empty cases from these locations. Whilst the mass of sediment moved by individual larvae is small, dense populations of Glossosomatidae larvae may have important consequences for the vertical distribution of sand in rivers. At our field site, A. fuscipes case density averaged 2192 cases m- 2, equivalent to 1.4 t km-1. This finding is important because in gravel-bed rivers frequented by Glossosomatidae larvae, sediment transport is typically limited by the availability of entrainable fine grain sediment at the surface. We discuss the implications of this sediment movement fo

Landscapes and ecosystems are the result of two-way interactions between hydro-geomorphic and biological processes. Many animals, particularly those that build structures or transport sediment, are important biogeomorphic agents. Glossosomatidae caddisfly larvae (Insecta, Trichoptera) are globally widespread and abundant inhabitants of gravel-bed rivers. Glossosomatidae build mobile cases from sand that they transport over the river bed. However, there is limited understanding on how Glossosomatidae bioconstructions may influence sand distribution in rivers or how their zoogeomorphic behaviours are influenced by hydraulics or characteristics of the river bed. First, we conducted surveys to quantify the magnitude of sand incorporated into Glossosomatidae (Agapetus fuscipes) cases within a UK river. Second, we studied A. fuscipes movement behaviour and quantified the direction and magnitude of sediment reworking, in a flume, under differing flow velocity and gravel size treatments. We found that 99 % of A. fuscipes larvae transported sediment vertically upwards. This resulted in an average conveyance per larvae of 0.06 g sand upwards by 25 mm (maximum of 50 mm). In gravel beds with a coarse surface layer, this resulted in displacement of sand from sheltered interstices onto the surface of exposed gravel particles. In the flume, this behaviour was maintained even at high flows, sufficient to entrain empty cases from these locations. Whilst the mass of sediment moved by individual larvae is small, dense populations of Glossosomatidae larvae may have important consequences for the vertical distribution of sand in rivers. At our field site, A. fuscipes case density averaged 2192 cases m- 2, equivalent to 1.4 t km-1. This finding is important because in gravel-bed rivers frequented by Glossosomatidae larvae, sediment transport is typically limited by the availability of entrainable fine grain sediment at the surface. We discuss the implications of this sediment movement fo

The disturbance of seafloor sediments by the activities of bottom-dwelling organisms, known as bioturbation, significantly alters the marine paleorecord by redistributing particles in the upper sediment layers. Consequently, ‘proxy’ signals recorded in these sediment particles, such as the size, abundance, or isotopic composition of plankton shells, are distorted by particle mixing. Accordingly, bioturbation can alter the apparent timing, duration, and magnitude of recorded events by smoothing climatic and oceanographic signals. In an extreme scenario, biological mixing can significantly obscure our view of the past by homogenizing the bioturbated layer, destroying sediment layering, and distorting the relative timing and intensity of past climatological events. Here we explore how bioturbation distorts proxy records of environmental events from a modeling perspective. First, we provide an overview and comparison of different numerical models created for simulating the movement and structural alteration of sediment by bioturbation. Next, we use an updated particle resolving model – iTURBO2 – to illustrate how various modes and intensities of bioturbation distort the signature of past climatological events, considering a range of conceptual shapes of vertical proxy profiles. Finally, we demonstrate how sampled proxy records can differ due to the combined effects of particle mixing and differential abundance changes that often concur with environmental transitions. We make the iTURBO2 MATLAB code openly available to facilitate further exploration of proxy biases due to bioturbation to aid the interpretation of the climatological record preserved in marine sediments.

More than 70% of the Earth is covered by water, and most of the sea floor consists of soft sediments, such as mud, clay and sand. Thus, soft sediments form one of the most important habitats on Earth, with a high diversity of organisms. However, the sediments in coastal areas are often subject to anthropogenic pollutants, and current remediation methods are often both costly and destructive on the ecosystem. Benthic macrofauna, i.e., sediment-living invertebrates larger than 1 mm, sustain a variety of ecosystem functions in the sediment by their activities; they oxygenate the sediment, redistribute particles and nutrients, and are also important secondary producers. Therefore, it is essential to maintain healthy benthic ecosystems and to study effects of various disturbances on benthic species composition and their recovery trajectory after disturbance, a process called ecological succession. The aims of this PhD thesis were to investigate: 1) how benthic marine invertebrate communities in a Norwegian fjord respond to thin-layer capping with activated carbon, a recently proposed technique to remediate contaminated sediments in situ in a more cost-efficient and less ecosystem destructive manner, 2) how benthic community composition in sediments from the Baltic Sea is explained by environmental variables and concentrations of polycyclic aromatic hydrocarbons (PAHs) and metals, and 3) how well current benthic quality assessment indices as well as functional indices represent these disturbances. The remediation method with activated carbon had long-term negative effects on the benthic macrofauna (paper I-III). Up to nine years after the capping, the communities were still severely affected, with lower species diversity, abundance and biomass. Recolonization of key species, such as the brittle star Amphiura filiformis, did not occur in the capped fields. Further, functional indices calculating bioturbation and bioirrigation estimated significantly lower activities in the

Traces of past oceanic and environmental conditions are stored in deep sea sediments as ‘proxy records’. When these ‘proxy records’ are deciphered, they can contain valuable information that can be used to reconstruct past chemical and physical conditions of the ocean throughout time. Though, these records can be distorted by a variety of chemical, physical, and biological processes including bioturbation, dissolution, and variations in sedimentation rate, complicating the relationship between stratigraphic depth and age of a geochemical proxy, and making it more difficult to translate past climates and environments. As CO2 levels continue to rise in our atmosphere, an understanding of how past extreme warming events, such as the Paleocene-Eocene Thermal Maximum (PETM, ~55.9 Ma), impacted environmental conditions and ecosystem dynamics can better inform how our modern ocean ecosystems will react to anthropogenic warming. During the PETM, a rapid injection of isotopically light carbon into the ocean and/or atmosphere, indicated by a negative carbon isotope excursion (CIE), resulted in global warming, changes in ocean ecosystem dynamics including a severe benthic foraminifera extinction, and global dissolution of deep-sea carbonates due to shoaling of the calcite compensation depth (CCD). This subsequent dissolution erased the onset of the PETM CIE at many deep sea locations, while the impact on the deep sea macrobenthic community remains unexplored. In this dissertation I investigate the response of the deep sea benthic and infaunal macrofauna response to the PETM by quantifying bioturbation intensity utilizing the ichnofabric index (ii) by identifying and measuring trace fossil community change in 46 deep sea sediment cores. I find global decreases in trace fossil community size, with over half of the locations ceasing bioturbation following the onset of the PETM. I utilize a novel burrow-specific sampling technique to investigate the movement of bulk sediment withi

Radiocarbon (C-14) dating is often carried out upon multi-specimen samples sourced from bioturbated sediment archives, such as deep-sea sediment. These samples are inherently heterogeneous in age, but existing C-14 calibration techniques were originally developed for age homogeneous material, such as archaeological artifacts or individual tree rings. A lack of information about age heterogeneity leads to a systematic underestimation of a sample's true age range, as well as the possible generation of significant age-depth artifacts during periods of the Earth's history coinciding with highly dynamic atmospheric Delta C-14. Here, a new calibration protocol is described that allows for the application of sedimentological priors describing sediment accumulation rate, bioturbation depth and temporally dynamic species abundance. This Bayesian approach produces a credible calibrated age distribution associated with a particular laboratory C-14 determination and its associated sedimentological priors, resulting in an improved calibration, especially in the case of low sediment accumulation rates typical of deep-sea sediment. A time-optimized computer script (biocal) for the new calibration protocol is also presented, thus allowing for rapid and automated application of the new calibration protocol. This new calibration protocol could be applied within existing age-depth modeling software packages to produce more accurate geochronologies for bioturbated sediment archives.

More than 70% of the Earth is covered by water, and most of the sea floor consists of soft sediments, such as mud, clay and sand. Thus, soft sediments form one of the most important habitats on Earth, with a high diversity of organisms. However, the sediments in coastal areas are often subject to anthropogenic pollutants, and current remediation methods are often both costly and destructive on the ecosystem. Benthic macrofauna, i.e., sediment-living invertebrates larger than 1 mm, sustain a variety of ecosystem functions in the sediment by their activities; they oxygenate the sediment, redistribute particles and nutrients, and are also important secondary producers. Therefore, it is essential to maintain healthy benthic ecosystems and to study effects of various disturbances on benthic species composition and their recovery trajectory after disturbance, a process called ecological succession. The aims of this PhD thesis were to investigate: 1) how benthic marine invertebrate communities in a Norwegian fjord respond to thin-layer capping with activated carbon, a recently proposed technique to remediate contaminated sediments in situ in a more cost-efficient and less ecosystem destructive manner, 2) how benthic community composition in sediments from the Baltic Sea is explained by environmental variables and concentrations of polycyclic aromatic hydrocarbons (PAHs) and metals, and 3) how well current benthic quality assessment indices as well as functional indices represent these disturbances. The remediation method with activated carbon had long-term negative effects on the benthic macrofauna (paper I-III). Up to nine years after the capping, the communities were still severely affected, with lower species diversity, abundance and biomass. Recolonization of key species, such as the brittle star Amphiura filiformis, did not occur in the capped fields. Further, functional indices calculating bioturbation and bioirrigation estimated significantly lower activities in the

Radiocarbon (C-14) dating is often carried out upon multi-specimen samples sourced from bioturbated sediment archives, such as deep-sea sediment. These samples are inherently heterogeneous in age, but existing C-14 calibration techniques were originally developed for age homogeneous material, such as archaeological artifacts or individual tree rings. A lack of information about age heterogeneity leads to a systematic underestimation of a sample's true age range, as well as the possible generation of significant age-depth artifacts during periods of the Earth's history coinciding with highly dynamic atmospheric Delta C-14. Here, a new calibration protocol is described that allows for the application of sedimentological priors describing sediment accumulation rate, bioturbation depth and temporally dynamic species abundance. This Bayesian approach produces a credible calibrated age distribution associated with a particular laboratory C-14 determination and its associated sedimentological priors, resulting in an improved calibration, especially in the case of low sediment accumulation rates typical of deep-sea sediment. A time-optimized computer script (biocal) for the new calibration protocol is also presented, thus allowing for rapid and automated application of the new calibration protocol. This new calibration protocol could be applied within existing age-depth modeling software packages to produce more accurate geochronologies for bioturbated sediment archives.

Radiocarbon (C-14) dating is often carried out upon multi-specimen samples sourced from bioturbated sediment archives, such as deep-sea sediment. These samples are inherently heterogeneous in age, but existing C-14 calibration techniques were originally developed for age homogeneous material, such as archaeological artifacts or individual tree rings. A lack of information about age heterogeneity leads to a systematic underestimation of a sample's true age range, as well as the possible generation of significant age-depth artifacts during periods of the Earth's history coinciding with highly dynamic atmospheric Delta C-14. Here, a new calibration protocol is described that allows for the application of sedimentological priors describing sediment accumulation rate, bioturbation depth and temporally dynamic species abundance. This Bayesian approach produces a credible calibrated age distribution associated with a particular laboratory C-14 determination and its associated sedimentological priors, resulting in an improved calibration, especially in the case of low sediment accumulation rates typical of deep-sea sediment. A time-optimized computer script (biocal) for the new calibration protocol is also presented, thus allowing for rapid and automated application of the new calibration protocol. This new calibration protocol could be applied within existing age-depth modeling software packages to produce more accurate geochronologies for bioturbated sediment archives.

More than 70% of the Earth is covered by water, and most of the sea floor consists of soft sediments, such as mud, clay and sand. Thus, soft sediments form one of the most important habitats on Earth, with a high diversity of organisms. However, the sediments in coastal areas are often subject to anthropogenic pollutants, and current remediation methods are often both costly and destructive on the ecosystem. Benthic macrofauna, i.e., sediment-living invertebrates larger than 1 mm, sustain a variety of ecosystem functions in the sediment by their activities; they oxygenate the sediment, redistribute particles and nutrients, and are also important secondary producers. Therefore, it is essential to maintain healthy benthic ecosystems and to study effects of various disturbances on benthic species composition and their recovery trajectory after disturbance, a process called ecological succession. The aims of this PhD thesis were to investigate: 1) how benthic marine invertebrate communities in a Norwegian fjord respond to thin-layer capping with activated carbon, a recently proposed technique to remediate contaminated sediments in situ in a more cost-efficient and less ecosystem destructive manner, 2) how benthic community composition in sediments from the Baltic Sea is explained by environmental variables and concentrations of polycyclic aromatic hydrocarbons (PAHs) and metals, and 3) how well current benthic quality assessment indices as well as functional indices represent these disturbances. The remediation method with activated carbon had long-term negative effects on the benthic macrofauna (paper I-III). Up to nine years after the capping, the communities were still severely affected, with lower species diversity, abundance and biomass. Recolonization of key species, such as the brittle star Amphiura filiformis, did not occur in the capped fields. Further, functional indices calculating bioturbation and bioirrigation estimated significantly lower activities in the

Traces of past oceanic and environmental conditions are stored in deep sea sediments as ‘proxy records’. When these ‘proxy records’ are deciphered, they can contain valuable information that can be used to reconstruct past chemical and physical conditions of the ocean throughout time. Though, these records can be distorted by a variety of chemical, physical, and biological processes including bioturbation, dissolution, and variations in sedimentation rate, complicating the relationship between stratigraphic depth and age of a geochemical proxy, and making it more difficult to translate past climates and environments. As CO2 levels continue to rise in our atmosphere, an understanding of how past extreme warming events, such as the Paleocene-Eocene Thermal Maximum (PETM, ~55.9 Ma), impacted environmental conditions and ecosystem dynamics can better inform how our modern ocean ecosystems will react to anthropogenic warming. During the PETM, a rapid injection of isotopically light carbon into the ocean and/or atmosphere, indicated by a negative carbon isotope excursion (CIE), resulted in global warming, changes in ocean ecosystem dynamics including a severe benthic foraminifera extinction, and global dissolution of deep-sea carbonates due to shoaling of the calcite compensation depth (CCD). This subsequent dissolution erased the onset of the PETM CIE at many deep sea locations, while the impact on the deep sea macrobenthic community remains unexplored. In this dissertation I investigate the response of the deep sea benthic and infaunal macrofauna response to the PETM by quantifying bioturbation intensity utilizing the ichnofabric index (ii) by identifying and measuring trace fossil community change in 46 deep sea sediment cores. I find global decreases in trace fossil community size, with over half of the locations ceasing bioturbation following the onset of the PETM. I utilize a novel burrow-specific sampling technique to investigate the movement of bulk sediment withi

Digging mammals displace a large amount of soil, thereby strongly altering soil ecosystem processes such as nitrogen cycling through bioturbation. Although it is well known that bears displace a large amount of soil by digging for food and denning, there is negligible empirical evidence of the effects on soil properties. In the Shiretoko World Heritage site, we investigated the effects of brown bear digging for cicada nymphs on soil properties, such as soil water content, organic and inorganic nitrogen concentrations, and nitrogen mineralization rate that are important components of soil ecosystem function and are essential for plant growth. We compared the properties of soil recently dug by brown bears with undisturbed soil in larch plantations. We found that brown bear digging decreased soil water content, organic matter, inorganic nitrogen concentration, net mineralization rates. Our results suggest that soil digging by brown bear may reduce plant growth by decreasing soil nutrient availability, thereby diminishing the net primary production of the larch plantation at the study site.

Digging mammals displace a large amount of soil, thereby strongly altering soil ecosystem processes such as nitrogen cycling through bioturbation. Although it is well known that bears displace a large amount of soil by digging for food and denning, there is negligible empirical evidence of the effects on soil properties. In the Shiretoko World Heritage site, we investigated the effects of brown bear digging for cicada nymphs on soil properties, such as soil water content, organic and inorganic nitrogen concentrations, and nitrogen mineralization rate that are important components of soil ecosystem function and are essential for plant growth. We compared the properties of soil recently dug by brown bears with undisturbed soil in larch plantations. We found that brown bear digging decreased soil water content, organic matter, inorganic nitrogen concentration, net mineralization rates. Our results suggest that soil digging by brown bear may reduce plant growth by decreasing soil nutrient availability, thereby diminishing the net primary production of the larch plantation at the study site.

Radiocarbon (C-14) dating is often carried out upon multi-specimen samples sourced from bioturbated sediment archives, such as deep-sea sediment. These samples are inherently heterogeneous in age, but existing C-14 calibration techniques were originally developed for age homogeneous material, such as archaeological artifacts or individual tree rings. A lack of information about age heterogeneity leads to a systematic underestimation of a sample's true age range, as well as the possible generation of significant age-depth artifacts during periods of the Earth's history coinciding with highly dynamic atmospheric Delta C-14. Here, a new calibration protocol is described that allows for the application of sedimentological priors describing sediment accumulation rate, bioturbation depth and temporally dynamic species abundance. This Bayesian approach produces a credible calibrated age distribution associated with a particular laboratory C-14 determination and its associated sedimentological priors, resulting in an improved calibration, especially in the case of low sediment accumulation rates typical of deep-sea sediment. A time-optimized computer script (biocal) for the new calibration protocol is also presented, thus allowing for rapid and automated application of the new calibration protocol. This new calibration protocol could be applied within existing age-depth modeling software packages to produce more accurate geochronologies for bioturbated sediment archives.

Digging mammals displace a large amount of soil, thereby strongly altering soil ecosystem processes such as nitrogen cycling through bioturbation. Although it is well known that bears displace a large amount of soil by digging for food and denning, there is negligible empirical evidence of the effects on soil properties. In the Shiretoko World Heritage site, we investigated the effects of brown bear digging for cicada nymphs on soil properties, such as soil water content, organic and inorganic nitrogen concentrations, and nitrogen mineralization rate that are important components of soil ecosystem function and are essential for plant growth. We compared the properties of soil recently dug by brown bears with undisturbed soil in larch plantations. We found that brown bear digging decreased soil water content, organic matter, inorganic nitrogen concentration, net mineralization rates. Our results suggest that soil digging by brown bear may reduce plant growth by decreasing soil nutrient availability, thereby diminishing the net primary production of the larch plantation at the study site.

Digging mammals displace a large amount of soil, thereby strongly altering soil ecosystem processes such as nitrogen cycling through bioturbation. Although it is well known that bears displace a large amount of soil by digging for food and denning, there is negligible empirical evidence of the effects on soil properties. In the Shiretoko World Heritage site, we investigated the effects of brown bear digging for cicada nymphs on soil properties, such as soil water content, organic and inorganic nitrogen concentrations, and nitrogen mineralization rate that are important components of soil ecosystem function and are essential for plant growth. We compared the properties of soil recently dug by brown bears with undisturbed soil in larch plantations. We found that brown bear digging decreased soil water content, organic matter, inorganic nitrogen concentration, net mineralization rates. Our results suggest that soil digging by brown bear may reduce plant growth by decreasing soil nutrient availability, thereby diminishing the net primary production of the larch plantation at the study site.

Landscapes and ecosystems are the result of two-way interactions between hydro-geomorphic and biological processes. Many animals, particularly those that build structures or transport sediment, are important biogeomorphic agents. Glossosomatidae caddisfly larvae (Insecta, Trichoptera) are globally widespread and abundant inhabitants of gravel-bed rivers. Glossosomatidae build mobile cases from sand that they transport over the river bed. However, there is limited understanding on how Glossosomatidae bioconstructions may influence sand distribution in rivers or how their zoogeomorphic behaviours are influenced by hydraulics or characteristics of the river bed. First, we conducted surveys to quantify the magnitude of sand incorporated into Glossosomatidae (Agapetus fuscipes) cases within a UK river. Second, we studied A. fuscipes movement behaviour and quantified the direction and magnitude of sediment reworking, in a flume, under differing flow velocity and gravel size treatments. We found that 99 % of A. fuscipes larvae transported sediment vertically upwards. This resulted in an average conveyance per larvae of 0.06 g sand upwards by 25 mm (maximum of 50 mm). In gravel beds with a coarse surface layer, this resulted in displacement of sand from sheltered interstices onto the surface of exposed gravel particles. In the flume, this behaviour was maintained even at high flows, sufficient to entrain empty cases from these locations. Whilst the mass of sediment moved by individual larvae is small, dense populations of Glossosomatidae larvae may have important consequences for the vertical distribution of sand in rivers. At our field site, A. fuscipes case density averaged 2192 cases m- 2, equivalent to 1.4 t km-1. This finding is important because in gravel-bed rivers frequented by Glossosomatidae larvae, sediment transport is typically limited by the availability of entrainable fine grain sediment at the surface. We discuss the implications of this sediment movement fo

Landscapes and ecosystems are the result of two-way interactions between hydro-geomorphic and biological processes. Many animals, particularly those that build structures or transport sediment, are important biogeomorphic agents. Glossosomatidae caddisfly larvae (Insecta, Trichoptera) are globally widespread and abundant inhabitants of gravel-bed rivers. Glossosomatidae build mobile cases from sand that they transport over the river bed. However, there is limited understanding on how Glossosomatidae bioconstructions may influence sand distribution in rivers or how their zoogeomorphic behaviours are influenced by hydraulics or characteristics of the river bed. First, we conducted surveys to quantify the magnitude of sand incorporated into Glossosomatidae (Agapetus fuscipes) cases within a UK river. Second, we studied A. fuscipes movement behaviour and quantified the direction and magnitude of sediment reworking, in a flume, under differing flow velocity and gravel size treatments. We found that 99 % of A. fuscipes larvae transported sediment vertically upwards. This resulted in an average conveyance per larvae of 0.06 g sand upwards by 25 mm (maximum of 50 mm). In gravel beds with a coarse surface layer, this resulted in displacement of sand from sheltered interstices onto the surface of exposed gravel particles. In the flume, this behaviour was maintained even at high flows, sufficient to entrain empty cases from these locations. Whilst the mass of sediment moved by individual larvae is small, dense populations of Glossosomatidae larvae may have important consequences for the vertical distribution of sand in rivers. At our field site, A. fuscipes case density averaged 2192 cases m- 2, equivalent to 1.4 t km-1. This finding is important because in gravel-bed rivers frequented by Glossosomatidae larvae, sediment transport is typically limited by the availability of entrainable fine grain sediment at the surface. We discuss the implications of this sediment movement fo

Bioirrigation is a process corresponding to animal-induced transport of porewater solute or exchange between interstitial and overlying waters. How and why the burrowing macrobenthos complete this process remain unclear. Here, we used two infaunal-behavior observation devices to investigate the ventilation behaviors of the benthic polychaete Perinereis aibuhitensis Grube, a species that is widespread along the Asian coast with a wide temperature range, at various temperatures (5°C, 10°C, 15°C, 20°C, and 25°C). The two typical movement behaviors of P. aibuhitensis, axial crawling and radial undulation, as well as associated parameters, were delimited and quantified. We found that the radial undulation frequency of P. aibuhitensis and the associated pumping rate (PR) increased significantly with temperature (T, 5-25°C); this relationship can be described by the regression equation PR = −0.0067T2 + 0.29T - 0.52 (R2 = 0.749, P < 0.05; n = 15). The relationship between axial crawling velocity (ACV) and temperature (T, 5-25°C) can be expressed by the regression equation ACV = -0.0001T3 + 0.0059T2 - 0.063T + 0.28 (R2 = 0.997, P<0.05; n = 15). In general, pumping efficiency increased as temperature decreased, implying that the polychaete increasingly conserved energy at lower temperatures. Peak pumping volume (4.36 L d-1) was observed at 25°C, as a result of radial undulations. Thus, we concluded that radial undulation was the primary movement that led to bioirrigation. The dissolved oxygen demand was the key factor driving the initiation of radial undulation, and the specific aim of radial undulation was to increase oxygen availability by pumping new seawater into the burrow. Thus, radial undulation is critical for polychaete survival. The dissolved oxygen threshold level at which pumping was initiated increased with temperature, suggesting more energy conserved at lower temperatures. This pumping strategy of P. aibuhitensis is consistent with optimality theory, and is her

Radiocarbon (C-14) dating is often carried out upon multi-specimen samples sourced from bioturbated sediment archives, such as deep-sea sediment. These samples are inherently heterogeneous in age, but existing C-14 calibration techniques were originally developed for age homogeneous material, such as archaeological artifacts or individual tree rings. A lack of information about age heterogeneity leads to a systematic underestimation of a sample's true age range, as well as the possible generation of significant age-depth artifacts during periods of the Earth's history coinciding with highly dynamic atmospheric Delta C-14. Here, a new calibration protocol is described that allows for the application of sedimentological priors describing sediment accumulation rate, bioturbation depth and temporally dynamic species abundance. This Bayesian approach produces a credible calibrated age distribution associated with a particular laboratory C-14 determination and its associated sedimentological priors, resulting in an improved calibration, especially in the case of low sediment accumulation rates typical of deep-sea sediment. A time-optimized computer script (biocal) for the new calibration protocol is also presented, thus allowing for rapid and automated application of the new calibration protocol. This new calibration protocol could be applied within existing age-depth modeling software packages to produce more accurate geochronologies for bioturbated sediment archives.

The disturbance of seafloor sediments by the activities of bottom-dwelling organisms, known as bioturbation, significantly alters the marine paleorecord by redistributing particles in the upper sediment layers. Consequently, ‘proxy’ signals recorded in these sediment particles, such as the size, abundance, or isotopic composition of plankton shells, are distorted by particle mixing. Accordingly, bioturbation can alter the apparent timing, duration, and magnitude of recorded events by smoothing climatic and oceanographic signals. In an extreme scenario, biological mixing can significantly obscure our view of the past by homogenizing the bioturbated layer, destroying sediment layering, and distorting the relative timing and intensity of past climatological events. Here we explore how bioturbation distorts proxy records of environmental events from a modeling perspective. First, we provide an overview and comparison of different numerical models created for simulating the movement and structural alteration of sediment by bioturbation. Next, we use an updated particle resolving model – iTURBO2 – to illustrate how various modes and intensities of bioturbation distort the signature of past climatological events, considering a range of conceptual shapes of vertical proxy profiles. Finally, we demonstrate how sampled proxy records can differ due to the combined effects of particle mixing and differential abundance changes that often concur with environmental transitions. We make the iTURBO2 MATLAB code openly available to facilitate further exploration of proxy biases due to bioturbation to aid the interpretation of the climatological record preserved in marine sediments., SCOPUS: re.j, info:eu-repo/semantics/published

More than 70% of the Earth is covered by water, and most of the sea floor consists of soft sediments, such as mud, clay and sand. Thus, soft sediments form one of the most important habitats on Earth, with a high diversity of organisms. However, the sediments in coastal areas are often subject to anthropogenic pollutants, and current remediation methods are often both costly and destructive on the ecosystem. Benthic macrofauna, i.e., sediment-living invertebrates larger than 1 mm, sustain a variety of ecosystem functions in the sediment by their activities; they oxygenate the sediment, redistribute particles and nutrients, and are also important secondary producers. Therefore, it is essential to maintain healthy benthic ecosystems and to study effects of various disturbances on benthic species composition and their recovery trajectory after disturbance, a process called ecological succession. The aims of this PhD thesis were to investigate: 1) how benthic marine invertebrate communities in a Norwegian fjord respond to thin-layer capping with activated carbon, a recently proposed technique to remediate contaminated sediments in situ in a more cost-efficient and less ecosystem destructive manner, 2) how benthic community composition in sediments from the Baltic Sea is explained by environmental variables and concentrations of polycyclic aromatic hydrocarbons (PAHs) and metals, and 3) how well current benthic quality assessment indices as well as functional indices represent these disturbances. The remediation method with activated carbon had long-term negative effects on the benthic macrofauna (paper I-III). Up to nine years after the capping, the communities were still severely affected, with lower species diversity, abundance and biomass. Recolonization of key species, such as the brittle star Amphiura filiformis, did not occur in the capped fields. Further, functional indices calculating bioturbation and bioirrigation estimated significantly lower activities in the

More than 70% of the Earth is covered by water, and most of the sea floor consists of soft sediments, such as mud, clay and sand. Thus, soft sediments form one of the most important habitats on Earth, with a high diversity of organisms. However, the sediments in coastal areas are often subject to anthropogenic pollutants, and current remediation methods are often both costly and destructive on the ecosystem. Benthic macrofauna, i.e., sediment-living invertebrates larger than 1 mm, sustain a variety of ecosystem functions in the sediment by their activities; they oxygenate the sediment, redistribute particles and nutrients, and are also important secondary producers. Therefore, it is essential to maintain healthy benthic ecosystems and to study effects of various disturbances on benthic species composition and their recovery trajectory after disturbance, a process called ecological succession. The aims of this PhD thesis were to investigate: 1) how benthic marine invertebrate communities in a Norwegian fjord respond to thin-layer capping with activated carbon, a recently proposed technique to remediate contaminated sediments in situ in a more cost-efficient and less ecosystem destructive manner, 2) how benthic community composition in sediments from the Baltic Sea is explained by environmental variables and concentrations of polycyclic aromatic hydrocarbons (PAHs) and metals, and 3) how well current benthic quality assessment indices as well as functional indices represent these disturbances. The remediation method with activated carbon had long-term negative effects on the benthic macrofauna (paper I-III). Up to nine years after the capping, the communities were still severely affected, with lower species diversity, abundance and biomass. Recolonization of key species, such as the brittle star Amphiura filiformis, did not occur in the capped fields. Further, functional indices calculating bioturbation and bioirrigation estimated significantly lower activities in the

More than 70% of the Earth is covered by water, and most of the sea floor consists of soft sediments, such as mud, clay and sand. Thus, soft sediments form one of the most important habitats on Earth, with a high diversity of organisms. However, the sediments in coastal areas are often subject to anthropogenic pollutants, and current remediation methods are often both costly and destructive on the ecosystem. Benthic macrofauna, i.e., sediment-living invertebrates larger than 1 mm, sustain a variety of ecosystem functions in the sediment by their activities; they oxygenate the sediment, redistribute particles and nutrients, and are also important secondary producers. Therefore, it is essential to maintain healthy benthic ecosystems and to study effects of various disturbances on benthic species composition and their recovery trajectory after disturbance, a process called ecological succession. The aims of this PhD thesis were to investigate: 1) how benthic marine invertebrate communities in a Norwegian fjord respond to thin-layer capping with activated carbon, a recently proposed technique to remediate contaminated sediments in situ in a more cost-efficient and less ecosystem destructive manner, 2) how benthic community composition in sediments from the Baltic Sea is explained by environmental variables and concentrations of polycyclic aromatic hydrocarbons (PAHs) and metals, and 3) how well current benthic quality assessment indices as well as functional indices represent these disturbances. The remediation method with activated carbon had long-term negative effects on the benthic macrofauna (paper I-III). Up to nine years after the capping, the communities were still severely affected, with lower species diversity, abundance and biomass. Recolonization of key species, such as the brittle star Amphiura filiformis, did not occur in the capped fields. Further, functional indices calculating bioturbation and bioirrigation estimated significantly lower activities in the

Pheidole fallax is one the most abundant ants in sites where coal mines have undergone rehabilitation and in forests without mine intervention. The impact that this species may have as an ecosystem engineer needs to be assessed. We aimed to test whether P. fallax nests have an effect on soil chemical properties, to characterize the organic debris found in the refuse piles, and to describe nest architecture as proxy of the bioturbation effect. The study was carried out in a coal mine in Colombia, in sites with 16 and 20 years of rehabilitation. Samples were taken from inside the nests, from the external refuse pile, and from a control treatment one meter away from the nest. The three sample types were subjected to chemical analysis and near-infrared spectra (NIRS). The biomass of items from the 20-year site was significantly greater, and P. fallax use food resources of different trophic levels, with arthropods and seeds being the main items in their diet. The NIRS analysis enabled us to distinguish the origin of the sample: refuse pile, interior of nest, or control soil. No statistical differences were found between the soil of the nests and control soil. High contents of organic matter and other parameters contributed to the soil nutrient pool through accumulation of organic debris in the refuse piles. Nest molds presented an asymmetric architecture, with mean volume ranging from 30 to 105.7 cm3 and an average of 11.8 chambers per nest. The construction and maintenance of nests may play an important role in the reestablishment of ecological and hydrological processes, such as bioturbation and water infiltration, respectively.

Tidal flats are biogeomorphic landscapes, shaped by physical forces and interaction with benthic biota. We used a metabolic approach to assess the overarching effect of bioturbators on tidal landscapes. The benthic bivalve common cockle (Cerastoderma edule) was used as model organism. The effect of C. edule on sediment resuspension was approximated as a function of the overall population metabolic rate per unit of area. We combined i) laboratory observations on how C. edule affect sediment resuspension along gradients of bioturbation activity, sediment cohesiveness and hydrodynamic force with ii) spatial data on the natural distribution of intertidal C. edule populations. This allowed us to build an integrated model of the C. edule effect on sediment resuspension along the tidal gradient. Owing to the temperature dependence of metabolic rate, the model also accounted for seasonal variation in bioturbators activity. Laboratory experiments indicated that sediment resuspension is positively related to the metabolic rate of the C. edule population especially in cohesive sediments. Based on this observation, we predicted a clear spatial and seasonal pattern in the relative importance of C. edule contribution to sediment resuspension along a tidal transect. At lower elevations, our model indicates that hydrodynamics overrules biotic effects; at higher elevations, inter-tidal hydrodynamics should be too low to suspend bioturbated sediments. The influence of C. edule on sediment resuspension is expected to be maximal at the intermediate elevation of a mudflat, owing to the combination of moderate hydrodynamic stress and high bioturbator activity. Also, bio-mediated sediment resuspension is predicted to be particularly high in the warm season. Research into metabolic dependency of bio-mediated sediment resuspension may help to place phenomenological observations in the broader framework of metabolic theories in ecology and to formulate general expectations on the coastal

Benthic macrofauna are a key component of intertidal ecosystems. Their mobility and behavior determine processes like nutrient cycling and the biogeomorphic development of intertidal flats. Many physical drivers of benthic macrofauna behavior, such as sediment grain size, have been well-studied. However, little is known about how sediment bulk density (a measure of sediment compaction and water content) affects this behavior. We investigated the effect of bulk density on the burrowing rate, burrowing depth, bioturbation activity, and oxygen consumption of bivalves (Limecola balthica, Scrobicularia plana, and Cerastoderma edule) and polychaetes (Hediste diversicolor and Arenicola marina) during a 29-day mesocosm experiment. We compared four sediment treatments consisting of two sediments of differing grain size classes (sandy and muddy) with two bulk densities (compact and soft). Overall, bulk density had a strong effect on benthic macrofauna behavior. Benthic macrofauna burrowed faster and bioturbation more intensely in soft sediments with low bulk density, regardless of grain size. In addition, L. balthica burrowed deeper in low bulk density sediment. Finally, we found that larger bivalves (both C. edule and S. plana) burrowed slower in compact sediment than smaller ones. This study shows that benthic macrofauna change their behavior in subtle but important ways under different sediment bulk densities which could affect animal-sediment interactions and tidal flat biogeomorphology. We conclude that lower bulk density conditions lead to more active macrofaunal movement and sediment reworking.

Sediment-stabilizing and -destabilizing organisms, i.e. microphytobenthos (biofilms) and macrozoobenthos (bioturbators), affect the erodibility of muddy sediments, potentially altering large-scale estuarine morphology. Using a novel eco-morphodynamic model of an idealized estuary, we investigate eco-engineering effects of microphytobenthos and two macrozoobenthic bioturbators. Local mud erodibility is based on species pattern predicted through hydrodynamics, soil mud content, competition and grazing. Mud resuspension and export is enhanced under bioturbation and prevented under biostabilization through respective exposure and protection of the supra- and intertidal. Bioturbation decreases mud thickness and bed elevations, which increases net mud fluxes. Microphytobenthos reduces erosion, leading to a local mud increase of intertidal sediments. In multi-species scenarios, an effective mud-prone bioturbator strongly alters morphology, exceeding that of a more abundant sand-prone moderate species, showing that morphological change depends on species traits as opposed to abundance. Altering their habitat, the effective mud-prone bioturbator facilitates expansion of the sand-prone moderate bioturbator. Grazing and species competition favor species distributions of dominant bioturbators. Consequently, eco-engineering affects habitat conditions while species interactions determine species dominance. Our results show that eco-engineering species determine the mud content of the estuary, which suggests large effects on the morphology of estuaries with aggravating habitat degradation.

Bioturbation has long been considered an antagonist of microbialite development and preservation, because metazoan grazing and burrowing destroy benthic microbial communities. However, metazoan bioturbation, in conjunction with microbial accretion, may have had a significant role in the morphogenesis of some columnar microbialites, as suggested by the case study presented and by some Phanerozoic and Upper Proterozoic analogues discussed here. Late Miocene in age, the studied microbial biostrome developed in a western Mediterranean restricted shallow-water platform dominated by grainy sediments and with a notable influence of bioturbation. This study is focused on the complex accretionary history of the columnar microbialite biostrome and on its striking dark grey colour, which is attributed to Mn-oxyhydroxides precipitated during meteoric diagenesis linked to subaerial exposure. The characteristic columnar structure of the microbialite biostrome has features consistent with an accretionary origin of the columns, but also has features suggesting metazoan disruption. Therefore, a new morphogenetic model for columnar microbialites is presented, highlighting the concomitant roles of microbial accretion, bioturbation and grainy sediment infill of the intercolumn space. Whether this model is an exception or a rule, should be tested on other examples of Phanerozoic and Upper Proterozoic columnar microbialites. Nevertheless, this model is a step forward in understanding the complex microbe–metazoan interactions as constructive coexistence rather than just as destructive competition., Ministerio de Ciencia e Innovación (MICINN), Gobierno de Aragón/FEDER, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub