-
How does landscape vegetation configuration regulate local channel initiation in rapidly expanding marsh?
-
Biogeomorphic interactions between tidal channels and marsh plants play a crucial role in enhancing coastal resilience to climate change. Previous studies linking the channel formation with vegetation dynamics predominantly focused on the early initiation, characterized by local-scale plant-flow feedbacks. However, the influence of rapid changes in landscape-scale vegetation pattern on the channel initiation remains poorly understood, especially in micro-tidal system. In this study, we investigated this relationship through biogeomorphic modeling combined with the analysis of satellite images in a rapidly expanding marsh in China under Spartina alterniflora invasion. The satellite images demonstrated the increase in drainage density and the decrease in unchanneled path length following plant encroachment. Our modeling results showed that local flow acceleration between vegetation patches was insufficient to initiate channels rapidly before the merging of isolated patches under micro-tidal conditions. With plant expansion, the continuous marsh caused landscape flow diversion from homogenous platform flow to concentrated channel flow, which promoted evident tributary channel initiation in the landward marsh zone. The vegetation removal scenarios further highlighted that the flow divergence from adjacent platforms due to the spatial heterogeneity in plant configuration amplified the magnitude of local hydrodynamics and further channel incision. Our findings emphasize that the initiation of tidal channels not only depends on local plant-flow interaction but is largely driven by landscape vegetation configuration under micro-tidal conditions.
Located in
Library
/
RBINS Staff Publications 2024
-
Coastal marsh resilience: a study on the role of bio-geomorphic self-organization
-
Tidal marshes are valuable coastal ecosystems that are threatened by global climate warming and the resulting sea level rise. Whether they drown or continue to exist, depends on the trapping of sediments that builds up the land surface. Tidal channel networks, which typically occur within tidal marshes, are the major supply routes for sediments towards the marshes and hence are expected to affect the capacity of marshes to keep up with sea level rise by sediment trapping. The development and evolution of tidal channel networks and the sediment trapping are locally determined by so-called bio-geomorphic interactions between plants, water flow and sediment transport. However, the effect of different environmental variables on channel network formation remains poorly understood. In this research, we investigated the impact of spatio-temporal plant colonization patterns by means of flume experiments. Four scaled landscape scale experiments were conducted in the Metronome tidal facility, a unique flume that tilts periodically to generate tidal currents. Two control experiments without vegetation, a third experiment with a channel-fringing vegetation colonization pattern, and a fourth with patchy vegetation colonization pattern. Seeds were distributed by water in the channel-fringing experiment, while a manual sowing method was used to obtain laterally expanding circular patches in the patchy experiment. Our results show that vegetation and their respective colonization pattern affect channel network formation both on a landscape scale and local scale. More extensive and effective channel networks are found in vegetation experiments. These results indicate that channel-fringing or patchy recruitment strategies might produce landscapes that are more resilient to sea level rise.
Located in
Library
/
RBINS Staff Publications 2024
-
Contrasting saltmarsh vegetation impacts under increasing sea level rise rates
-
The resilience of saltmarshes mainly depends on their ability to gain elevation by sediment accretion to keep pace with sea level rise. While vegetation is known to facilitate sediment accretion at the plant scale by trapping mineral sediments and producing organic matter, the long-term impact at the landscape scale is still poorly understood. Here we use the biogeomorphic model Demeter to reveal contrasting vegetation impacts on spatial patterns of sediment accretion under different sea level rise regimes. Under contemporary sea level rise rates (2-10 mm/yr), vegetation inhibits sediment transport from tidal channels to platform interiors and creates levee-depression patterns. Hence, intertidal platforms accrete slower with vegetation than without, but this trend attenuates with increasing sea level rise rate, as water depth increases, and vegetation drag decreases. Under extreme sea level rise rate (20 mm/yr), platform interiors don’t keep up and turn into open water, while vegetation allows to preserve intertidal levees. Our results help to better understand some basic biophysical mechanisms that will control the fate of coastal wetlands under global climate change.
Located in
Library
/
RBINS Staff Publications 2024
-
Observations of tidal attenuation and amplification in a mangrove forest: channels as conduits
-
Mangroves are increasingly recognized as an effective nature-based coastal defence strategy. Mangrove trees are proven to reduce the height of propagating long-period waves such as storm tides and extreme sea levels. Existing empirical studies, however, are limited to small scales (~10²-10³ m) or only cover continuous belts of mangroves. Here we present water level measurements along a 20 km channel and in the surrounding mangrove forests for regular neap- and spring tides in a natural mangrove forest in the Guayas Delta, Ecuador. For tides with peak water levels which are high enough to flood the surrounding mangroves, inundation levels reached 45 cm with attenuation rates up to 40 cm/km. Along the entire 20 km channel, however, no attenuation occurred. Instead, we measured amplification with rates varying between 4.3 and 4.6 cm/km. Amplification rates increased with peak water level until water levels were high enough to flood the surrounding mangroves, upon which amplification rates decreased with peak water level. The latter implies that with higher peak levels, such as during an extreme sea level event, the capacity of mangroves to dampen amplification or even attenuate increases.
Located in
Library
/
RBINS Staff Publications 2024
-
A new Carboniferous ‘ctenacanth’ chondrichthyan and the evolution of brain-pituitary gland communication modes
-
The ‘ctenacanths’ are Palaeozoic chondrichthyans known from the Upper Devonian to the Middle Permian. Their systematic status and relationships are still ambiguous, one of the reasons being the absence of clear diagnostic neurocranial characters. Here we report a new isolated 3D-preserved partial braincase from the Middle Pennsylvanian of the Excello shale from Oklahoma, USA. This study will provide putative neurocranial characters defining this group. The exceptional preservation of its pituitary region allows the reconstruction of the vascularization of the gland. The pituitary vascular system is involved in the hypothalamic-hypophysial communication and transport of hormones that regulate the major physiological functions in vertebrates. Comparisons of the vascularization of the pituitary of this fossil chondrichthyan to a new Devonian placoderm from Peru and to both embryos and juveniles from extant sharks and chimaeras provide data for future research on the evolution of the brain-hypophysis communication modes.
Located in
Library
/
RBINS Staff Publications 2026
-
Upper Carboniferous - Lower Permian fishes and conodonts from Peru: biofacies and stratigraphy of the Madre de Dios Basin
-
The Late Palaeozoic Ice Age (LPIA) is characterized by glacioeustatic transgressive–regressive cycles, whose signatures are commonly recorded in stratigraphic sequences and associated environmental parameters. Although these glacioeustatic cycles have been documented in Late Carboniferous–Early Permian successions from the Amazonian basins of Brazil, equivalent deposits remain poorly known in the Andean region. This region, particularly Bolivia and Peru, preserves extensive carbonate outcrops from this interval that provide valuable insights into paleoenvironments and faunal assemblages. The Copacabana Formation is composed by warm-water carbonates, evaporites, and open-marine facies. Its broad distribution and cyclicity reflect pronounced climatic and eustatic fluctuations during the LPIA. Studies carry on Puerto Arturo section (Puno, Peru) have revealed abundant early chondrichthyans remains, including Protacrodus, Denaea, Stethacanthus, and Cooleyella amazonensis—preserved as teeth and scales. The relative abundance of these taxa suggests shallow-water conditions (Protacrodus biofacies). In addition, a diverse conodont assemblage, including Idiognathodus, Streptognathodus, Sweetognathodus, and Gondolella, has also been identified. Conodont biostratigraphy and biofacies distributions, based on taxonomic composition and relative abundance per bed, indicate mid-ramp environments characterized by Idiognathodus–Streptognathodus biofacies and outer-ramp settings dominated by Gondolella biofacies. This integrated approach combining sequence-stratigraphic, microfacies, and paleontological analyses provides the first robust paleoenvironmental reconstruction for this interval in Peru, significantly improving regional correlations and revealing new aspects of Palaeozoic diversity in western Gondwana.
Located in
Library
/
RBINS Staff Publications 2026
-
New fossils from the Devonian of Peru shed light on the unusual “dental” structure of the stem chondrichthyan Pucapampella
-
Pucapampella represents an enigmatic genus of non-acanthodian stem chondrichthyans known from the Lower to Middle Devonian (Emsian–Eifelian) of South America, particularly from Bolivia and Peru. Pucapampellids display a mosaic of primitive and derived traits. One of the most distinctive features concerns the structure of the dentition, which is unusual compared to other chondrichthyans. They possess “teeth” that are neither arranged into replacement tooth families (as in most crown chondrichthyans) nor part of dentigerous jaw bones or tooth whorls (as in acanthodians). Instead, their mandibular arches have been described as bearing a single series of sharp “teeth” supported directly by cartilage, without any intervening dermal bone. Paleontological fieldwork conducted in recent years in Devonian strata of the Puno region (southwestern Peru), near Lake Titicaca at an altitude of about 4,200 meters above sea level, has yielded a rich assemblage of new pucapampellid fossils, including exceptionally preserved mandibular remains. These specimens are preserved within phosphatic nodules embedded in grey shales from the upper part of the Chagrapi Formation, which records cyclic successions of dark and grey shales with fine sandstones deposited in a delta-influenced infralittoral marine setting. The upper member, rich in organic matter and phosphatic nodules, indicates episodes of deepening and anoxic conditions. Pucapampellid remains occur in Eifelian-aged levels containing a more diverse vertebrate fauna. Specimens were analyzed using synchrotron PPC-SRµCT, synchrotron μXRF elemental mapping, and paleohistological thin sections. Preliminary results reveal a unique dental architecture unlike any previously described in vertebrates. These findings suggest that the dental structures of pucapampellids represent tooth-like elements that are not homologous to the “true” teeth of other gnathostomes.
Located in
Library
/
RBINS Staff Publications 2026
-
Brain evolution of early placental mammals: the impact of the end-Cretaceous mass extinction on the the neurosensory system of our distant relatives
-
The end-Cretaceous mass extinction, 66 million years ago, profoundly reshaped the biodiversity of our planet. After likely originating in the Cretaceous, placental mammals (species giving live birth to well-developed young) survived the extinction and quickly diversified in the ensuing Paleocene. Compared to Mesozoic species, extant placentals have advanced neurosensory abilities, enabled by a proportionally large brain with an expanded neocortex. This brain construction was acquired by the Eocene, but its origins, and how its evolution relates to extinction survivorship and recovery, are unclear, because little is known about the neurosensory systems of Paleocene species. We used high-resolution computed tomography (CT) scanning to build digital brain models in 29 extinct placentals (including 23 from the Paleocene). We added these to data from the literature to construct a database of 98 taxa, from the Jurassic to the Eocene, which we assessed in a phylogenetic context. We find that the Phylogenetic Encephalization Quotient (PEQ), a measure of relative brain size, increased in the Cretaceous along branches leading to Placentalia, but then decreased in Paleocene clades (taeniodonts, phenacodontids, pantodonts, periptychids, and arctocyonids). Later, during the Eocene, the PEQ increased independently in all crown groups (e.g., euarchontoglirans and laurasiatherians). The Paleocene decline in PEQ was driven by body mass increasing much more rapidly after the extinction than brain volume. The neocortex remained small, relative to the rest of the brain, in Paleocene taxa and expanded independently in Eocene crown groups. The relative size of the olfactory bulbs, however, remained relatively stable over time, except for a major decrease in Euarchontoglires and some Eocene artiodactyls, while the petrosal lobules (associated with eye movement coordination) decreased in size in Laurasiatheria but increased in Euarchontoglires. Our results indicate that an enlarged, modern-style brain was not instrumental to the survival of placental mammal ancestors at the end-Cretaceous, nor to their radiation in the Paleocene. Instead, opening of new ecological niches post-extinction promoted the diversification of larger body sizes, while brain and neocortex sizes lagged behind. The independent increase in PEQ in Eocene crown groups is related to the expansion of the neocortex, possibly a response to ecological specialization as environments changed, long after the extinction. Funding Sources Marie Sklodowska-Curie Actions, European Research Council Starting Grant, National Science Foundation, Belgian Science Policy Office, DMNS No Walls Community Initiative.
Located in
Library
/
RBINS Staff Publications 2020
-
Phylogenetic position of Olbitherium (Mammalia, Perissodactyla) based on new material from the early Eocene Wutu Formation
-
The genus Olbitherium was originally described in 2004 from the early Eocene of the Wutu Formation in China as a ‘perissodactyl-like’ archaic ungulate. Described material of Olbitherium consists of partial dentaries with lower cheek teeth, isolated upper molars, and an isolated upper premolar. Subsequent collaborative fieldwork by Belgian and Chinese researchers discovered new material including a partial skull, the anterior portion of the dentary, and associated postcrania. In their general form, the skull and postcrania are similar to those of early perissodactyls. The new material provides a more complete picture of the upper dentition, and the anterior dentary demonstrates the presence of three lower incisors and a large canine, both ancestral features for perissodactyls. A phylogenetic analysis was conducted to test the affinities of Olbitherium, using a matrix of 321 characters and 72 taxa of placental mammals emphasizing perissodactyls and other ungulates. The results produced four shortest trees of 1981 steps. In all four trees, Olbitherium is the sister-taxon to all perissodactyls except Ghazijhippus. In contrast, when scoring was restricted to the originally described material, the results produced 16 shortest trees of 1970 steps, and Olbitherium nests well within Perissodactyla as sister-taxon to a clade including Lambdotherium and the brontotheriids Eotitanops and Palaeosyops. The new material not only supports the identification of Olbitherium as a perissodactyl, but it also suggests that it is significant for understanding the ancestral perissodactyl morphotype. Funding Sources U.S. National Science Foundation (DEB1456826), Chinese Ministry of Science and Technology (2009DFA32210), and Belgian Science Policy Office (BL/36/C54).
Located in
Library
/
RBINS Staff Publications 2020
-
The influence of pile driving noise on harbour porpoises
-
Located in
Library
/
RBINS Staff Publications 2017
