Flat Margin Research Articles

Taxonomic studies in Wedelia (Asteraceae, Heliantheae) reveal a new species for the Brazilian Cerrado

Wedelia is the largest genus of Ecliptinae (Heliantheae, Asteraceae), comprising about 110 species. The Brazilian Cerrado is a highly threatened phytogeographic domain, which harbors the richest flora in the world among other savannas. A new subshrubby species of Wedelia was revealed occurring in the central part of Cerrado and is herein described as W. tenuinervia. This new species resembles W. foliacea in vegetative traits but differs mainly by having leaves with brochidodromous venation, pistillate ray flowers, glandular trichomes on the abaxial surface of the leaf blade, corolla lobes and apical anther appendages, phyllaries abaxial surface strigillose and disc cypselae 4–5-angled, keeled at the angles, without basal scars or elaiosomes, and carpopodium inconspicuous (vs. acrodromous venation, neuter ray flower, abaxial surface of the leaf blade, corolla lobes and apical anther appendage lacking glandular trichomes, phyllaries abaxial surface setose or glabrescent, and disc cypselae biconvex, not keeled, with basal scars or elaiosomes, and carpopodium in two plates or one shallowly lobed). Among the species with pistillate ray flowers, W. tenuinervia can be morphologically related to W. oligocephala, differing mainly by the membranaceous leaf blades with flat margins, brochidodromous venation, and solitary capitula (vs. subcoriaceous leaf blades with revolute margins, acrodromous venation and capitula in dichasia). Illustrations, comments, a preliminary conservation status, and the typification of W. foliacea’s synonyms are proposed.

A new Angolan species from the Triaspis hypericoides complex (Malpighiaceae) based on macromorphology and palynology

Triaspis hypericoides currently comprises three accepted subspecies endemic to woodland savannas of southern continental Africa. After an unusual population belonging to this complex was collected in southwestern Angola, we re‐evaluated the classification of this group. This study was based on the analysis of type specimens, protologues, field photographs and herbarium sheets of all subspecies within T. hypericoides. We reinstate T. canescens, T. hypericoides and T. nelsonii based on differences in leaf, flower and fruit traits. Additionally, the Angolan population is proposed here as a new species of Triapis endemic to the dry miombo woodlands of Bicuar National Park, Huíla Province, southwestern Angola. Triaspis bicuarensis sp. nov. is easily distinguished from T. nelsonii by its alternate (versus opposite) leaves, ovate to widely ovate (versus widely ovate to very widely ovate) leaf laminas, rounded (versus sagittate) leaf base, flat (versus undulate) margins, sparsely white‐tomentose (versus glabrous to glabrescent) abaxial leaf surface, petiole 4–8 mm long (versus 2–3 mm long), compound inflorescences in thyrses (versus corymbs) and bracteoles inserted below apex of peduncles (versus in the middle of peduncles). An identification key to all species belonging to this species complex is presented alongside a complete morphological description for the new species, photographic plates and comments on the distribution, ecology, palynology and taxonomy. These results underline the need for continued revisions of the taxonomy of the neglected African genera of Malpighiaceae.

Changes in Vessel Traffic Disrupt Tidal Flats and Saltmarshes in the Tagus Estuary, Portugal

The Tagus Estuary is one of the largest in Europe with 320 km2, and it has been, for centuries, a gateway to Lisbon. This study focuses on the Moita-Montijo Bay and on the recent dynamics of its tidal flats and saltmarshes. Aerial photographs, orthomosaics, and very high-resolution satellite imagery were used to analyze landcover and shoreline changes. Tidal flats have shown expansion from 1977 to 1995, but since then, contraction dominated, with a change of position of the tidal flat edge of −2.8 m/year in the north bank and −4.2 m/year in the south bank of the Montijo channel. Most contraction occurred along the route of the fast transport catamarans that started operating in 1995, while in the sector without catamaran navigation, expansion was observed. Saltmarshes have been suffering contraction since 1958, with increased rates after 1995 (−0.38 to −0.44 m/year), especially along the catamaran route (−0.57 to −1.27 m/year). The analysis of the wake generated by different vessel types shows a wake increase with the catamarans, in agreement with the increase in contraction along the Montijo channel. Inside abandoned salt pans, saltmarshes expanded. Since 1995, major changes are also observed along the tidal flat margin, with the formation of coarse lag deposits of coarse sands and shells. Given the contraction increase associated with catamaran traffic and the resulting degradation of the tidal flat and the saltmarshes, it is important to introduce measures for containing contraction.

CHARACTERIZATION AND IDENTIFICATION OF SM4 BACTERIAL ISOLATE FROM Stylissa massa SPONSE AS PRODUCING ANTIMICROBIAL COMPOUNDS AGAINST PATHOGENIC BACTERIA

East Nusa Tenggara (NTT) is one of the archipelagic provinces in Indonesia with a sea area of 200,000 km² and contains potential marine resources including the Stylissa massa sponge. Bacteria have been known to associate with sponges and have the ability to produce antimicrobial compounds. This study aims to characterize, identify the 16S rRNA gene, and test the bioactive compounds of SM4 bacterial isolates from the Stylissa massa sponge. The bacterial isolates of SM4 were previously rejuvenated on NA medium, then characterized by macroscopic morphology, and biochemistry by citrate test and TSIA test. The culture was extracted using petroleum ether solvent and the antibacterial activity was tested against E. coli and S. aureus by the well method. The isolates were then identified based on the 16S rRNA gene by PCR method. The results showed that, SM4 isolates had small colony size, yellow color, round colony shape, flat elevation, flat margins, while biochemically they had positive results with Citrate and TSIA tests. The antagonist test of the SM4 bacterial isolate was found to have the ability to inhibit the growth of S. aureus and E. coli, while the antibacterial activity test of the bioactive compound bacterial isolate SM4 was known to have the ability to inhibit the growth of S .aureus with an inhibition zone of 1.99 mm and E. colli 1.56 mm. The results of the molecular identification of the bacterial isolate SM4 had 99% similarity with the Bacillus cereus strain Nr_074540.1

Classification of Coastal Belts on the Coral Coast of Viti Levu, Republic of Fiji, South Pacific, using the BCCS (Biophysical Cross-shore Classification System)

Finkl, C.W. and Makowski, C., 2022. Detailed interpretation of satellite images of coastal belts on the Coral Coast of Viti Levu, Republic of Fiji, South Pacific, using the BCCS (Biophysical Cross-shore Classification System). Journal of Coastal Research, 38(3), 491–511. Coconut Creek (Florida), ISSN 0749-0208. Lying on the southwest Fijian coast of Viti Levu, the Coral Coast is noted for its fringing coral reefs that extend for an overall alongshore length of about 80 km (from Momi to Suva), with the study area being a 32-km-long subset in the Sigatoka region. The fringing reefs, extending offshore for an average maximum distance of about 650 m, are broken into contiguous segments by deep-water cross-shore channels composing discrete coastal belts. When the fringing reef segments are combined with other onshore (terrestrial) eco-geomorphological units, they make up nine distinct coastal belts in the study area comprised by 35 domains. The cross-shore classification of the Coral Coast examples was based on application of the BCCS (Biophysical Cross-shore Classification System), which required interpretation of satellite images to comprehend cross-shore catenary (linked) sequences that had alongshore extent. Imagery from 2010 to 2017 was accessed to obtain the best possible views of each reef segment and adjacent mountain hinterland. Due to spatial limitations, capabilities of the Google Earth Pro platform were accessed to acquire sufficient interpretive details for compilation of cross-shore transectal archetypes and subarchetypes from the reef front to coastal mountain slopes. Typical cross-shore classificatory sequences consisted of Coral Reef (Cr), Flat (F), Beach (Be), and Mountain (M) archetypes that formed tetrasequent Cr-F-Be-M catenas. Although a limited number of small Delta (De) archetypes overrode back-reef flat margins, their frequency of occurrence was not a domainal characteristic. The occurrence of Developed (Dv) archetypes were more or less ubiquitous onshore, whereas alongshore bedrock outcrops of the Rock (R) archetype were rare. Because the scale of natural and anthropogenic features along the coast demanded a detailed (hectometric) coastal classification, the BCCS was applied on an experimental basis to ascertain its applicability as an exemplar for similar studies in insular settings elsewhere.

Late Pleistocene–Early Holocene human settlement and environmental dynamics in the southern Atacama Desert highlands (24.0°S–24.5°S, Northern Chile)

AbstractThe earliest known population of the Atacama Desert coincided with the Central Andean Pluvial Event II (CAPE II), an extensive pluvial event recorded during the Late Pleistocene–Early Holocene (13,800–8,500 cal years BP). A large number of archaeological sites from this period have been found along the borders of the Imilac and Punta Negra (24.5°S) high‐altitude basins (ca. 3,000 masl). By combining the results of proxy data obtained from geomorphological, sedimentological, and paleoecological (rodent middens) archives and the spatial location of archaeological sites and radiocarbon series analyses, this paper examines the links between human activities and paleoenvironmental dynamics at different times during CAPE II in the southern Atacama Desert. This is done at a finer spatial and temporal scale than previous studies. The first archaeological sites (ca. 12,000–11,200 cal years BP) are concomitant with increased paleowetland occurrence frequency. An occupational hiatus is recorded between 11,200 and 10,800 cal years BP, synchronous with a drop in precipitation and wetland development. This is followed by a displacement of the archaeological sites toward the south‐east of the Punta Negra Basin and concomitant again with a second peak of wetland development in the area (10,800–10,400 cal years BP) before the final abandonment of the salt flat margins.

New species of Lejeunea (Porellales: Lejeuneaceae) from Papua New Guinea

Three new species of Lejeunea (Lejeuneaceae) from Papua New Guinea are described and illustrated herein. They are L. heinarii, L. madangensis and L. marginedentata from Morobe, Madang and Sandaun (West Sepik) province, respectively. They were found growing as epiphytes on trees and inhabit the montane forests of the island. Lejeunea heinarii is characterized by the strongly inflated and inrolled leaf lobules, large reniform underleaves with retuse apices, and well-developed trigones with conspicuous intermediate thickenings (up to 4 per cell), while the distinguishing characters of L. madangensis are the 2-winged perianth keels, large reniform underleaves with cordate-auriculate bases, flat free margin of leaf lobules, and autoicy. Lejeunea marginedentata stood out among all its allies by the inflated perianths without keels, asymmetrical leaf lobes with strong arched dorsal margin and straight ventral margin, and the prominent dentate margin with acute teeth.

Macular hole closure patterns: an updated classification.

The classification of macular hole closure patterns (MHCPs) currently relies on time domain OCT allowing only "open" and "closed" statuses or is based on inner foveal contour shape. Both classification types give no information on retinal layer reconstitution. Novel sophisticated surgical techniques lead to previously unknown MHCPs, outdating existing classifications and urging new ones. The purpose of the present study is to introduce a new classification allowing proper description of all MHCPs resulting from newer surgeries and based on the restoration of retinal layers. Retrospective analysis of patients undergoing MH surgery with five different surgical techniques was performed. MHCPs were classified according to spectral domain optical coherence tomography (SD-OCT). Type 0: open MH (0A: flat margin, 0B: elevated, 0C: oedematous); type 1: closed MHs (1A: reconstitution all retinal layers; 1B interruption of the external layers; 1C interruption of internal layers); type 2: MH closed with autologous or heterologous filling tissue interrupting the normal foveal layered anatomy (2A: filling tissue through all layers; 2B reconstitution of normal inner retinal layers; 2C reconstitution of normal outer retinal layers; 2D H-shaped bridging of filling tissue). Closure rate was 95.2% (241/253). Surgical technique and vision correlated to closure pattern (p < 0.001). Type 1 MHCPs had the best post-operative visual acuity (VA) compared with type 2 and type 0 (p < 0.001). MHCPs 1A and 1C performed better than all others. MHCP at months 1 and 3 changed in 42/254 (16.5%) and remained stable in 212/254 (83.5%). Improvement in vision was higher in eyes with shifting closure pattern (0.57 ± 0.33 vs 0.51 ± 0.48 logMAR; p 0.021). MHCP classification based on retinal layer restoration properly comprises post-operative anatomic morphologies. MHCPs correlate the surgical technique and post-operative visual outcomes.

Penetrating Brain Injury in Children

Background: Accidental penetrating brain injury through supraorbital route is an unusual occurrence in emergency practice of civilian cases. At time, it could be potentially life threatening. We report an interesting case of supraorbital penetrating brain injury with an iron stick in a 12-year-old female patient. The stick was removed successfully through supraorbital exploration, without any neurovascular complications.&#x0D; Case Report: A 12-year-old female presented to our emergency department with injury to his right eye. History revealed that she was practicing marching band in her school as the leader. As she thrown the iron stick, she lost balance and that iron stick entered into her right supraorbital. Her Glasgow Coma Scale (GCS) score, on admission, was 15. There was circumferential laceration on the right supraorbital, flat margins, visible iron stick penetration with diameter 3 cm but no active bleeding was found. Rest of the physical and neurological examination findings were within normal limits. He was resuscitated promptly according to the advanced trauma life support system.&#x0D; Discussion: Intravenous fluids are given and efforts are taken to maintain high blood oxygen levels.Management of patients with transorbital brain injuries and foreign bodies in situ should follow basic surgical principles, including removal of the object under direct vision in order to reduce further brain tissue damage by the foreign bodies catching on bone fragments. Following removal of the foreign body, thorough debridement with removal of all involved skull bone and foreign materials, hematoma evacuation followed by careful hemostasis along the trajectory, and meticulous dural closure to reduce the possibility of CSF fistula are mandatory. A transorbital or transcranial approach can be chosen depending on the location of the fragment.&#x0D; Conclusion: In conclusion, supraorbital penetrating brain injury caused by an iron stick is a rare but fatal event. High index of suspicion toward the presence of foreign bodies and emergent surgical intervention is to be considered in spite of consistent lack of evidence on CT scan. Retrieval should be performed on the operating table under direct vision only after preoperative imaging of neurovascular structures.&#x0D; Keyword: Penetrating brain injury, Iron Stick

Eugenia caipora, a new species of Eugenia sect. Pseudeugenia (Myrtaceae) from northeastern Brazil

Eugenia caipora (Myrtaceae), a new species from northeastern Brazil, is here described; it occurs in restinga vegetation, Tabuleiros litorâneos (Tabuleiro savanna), and seasonal forests in Ceará, Rio Grande do Norte, Paraíba, Pernambuco and Alagoas. The new species is morphologically similar to Eugenia azuruensis, though differing by the leaf blades abaxially glabrous to puberulent (vs. densely tomentose in E. azuruensis), non-mucronate (vs. mucronate), with flat margins (vs. revolute), calyx lobes 4–5 mm wide (vs. 6–10 mm), rounded at the apex (vs. apiculate), and petals 5–15 mm long (vs. 20–24 mm). A table of diagnostic characters for the new and related species and photographs of morphological diagnostic characters are provided.

Lateral control of an Aerosonde facing tolerance in parameters and operation speed: performance robustness study

The aim is to acquire low variance roll responses (performance robustness) of control of an Aerosonde despite the high level of tolerances in aerodynamic parameters and working speed. In this respect, fractional-order proportional plus integral and derivative (FOPID) is a valuable option; others are H∞ and μ synthesis. FOPID can tolerate system uncertainty by maintaining a wide open-loop flat phase margin band. All three methods are worked out using the linearized system model and deliver (at least initially) high-integer-order controllers. The uncertainty level is not explicitly considered in H∞, but it may be presented in the μ synthesis and FOPID. The uncertainty presentation in the modified fractional-order controller (mFOC) design is through a Φd curve. The Φd curve is fitted to the mean of the upper and lower bands of the phase margins distribution map of the random systems. It is shown that the mFOC design perfectly secures the desired phase margin flatness. The controllers are applied to the roll of an unmanned aircraft vehicle with a 30% tolerance in the aerodynamic parameters, and operation speed and robustness in performance is evaluated. The simulation results indicate that the mFOC design renders more coherent responses than what H∞ and µ synthesis design deliver. This is confirmed through extensive simulations.

Classification of the Relhania generic group (Asteraceae, Gnaphalieae) revisited using molecular phylogenetic analysis

Phylogenetic relationships within the Relhania generic group, a southern African lineage of 45 yellow-flowered daisy species, are examined using parsimony and Bayesian analysis of plastid DNA, nuclear DNA, and morphological characters. The resulting phylogenetic hypothesis indicates that the species fall into two clades, one comprising the genera containing short-lived (annual / biennial) species, and the other exclusively perennial. Within the perennial clade, containing six genera, several well-supported and morphologically coherent clades are recovered. However, there is substantial generic non-monophyly and many relationships lack resolution, with several species being unplaced. Subdivision into multiple genera would require the recognition of up to twelve small or monospecific genera, and lack of resolution would render this solution potentially unstable. Instead, the six currently-recognised perennial genera Antithrixia, Comborhiza, Oreoleysera, Relhania and Rosenia are here synonymized under the oldest name, Oedera Linnaeus. An infrageneric taxonomy comprising eight sections is proposed for Oedera sensu amplo. This new, enlarged concept of Oedera is defined by the perennial life-history, by leaves with involute or flat margins, by pappus bristles (if present) that are never plumose, and by a base chromosome number of x = 7. Keys to the genera, an updated description of Oedera sensu amplo, and keys to the sections and species are provided. A total of 25 new combinations is made.

Re-characterization of Gymelloxes with a re-description of Gymelloxes terea from Central America (Lepidoptera: Hepialidae).

The hepialid genus Gymelloxes Viette, 1952 is characterized by, and differs from all other genera, by the male genitalia and a combination of characters. G. terea is redescribed due to the brevity of the original description. The male genitalia of Gymelloxes terea (Schaus, 1892) include two features that are unique within the Hepialidae - a posteriorly angled and digitiform tergal lobe, and two shallow, peg-like processes on the posterior margin of the saccus. The male phallus also exhibits minute sclerotized spicules or spots on the apex of an otherwise membranous tube. The external genitalia of the female includes a sclerotized antevaginalis with a broad, dorsally projecting, flat central margin. The species is included within the cibyrine clade of Hepialidae by the structure of the tergosternal connection and narrow spacing between Sc and R on the hindwing. The potential systematic significance of specialized similarities shared with other cibyrine Hepialidae is discussed. A lectotype of Dalaca terea Schaus, 1892 is here designated.

The drivers of biogeochemistry in beach ecosystems: A cross-shore transect from the dunes to the low-water line

This study addresses key processes in high-energy beach systems using an interdisciplinary approach. We assess spatial variations in subsurface pore water residence times, salinity, organic matter (OM) availability, and redox conditions and their effects on nutrient cycles as well as on microbial community patterns and microphytobenthos growth. At the study site on Spiekeroog Island, southern North Sea, beach hydrology is characterized by the classical zonation with an upper saline plume (USP), a saltwater wedge, and a freshwater discharge tube in between. Sediment and pore water samples were taken along a cross-shore transect from the dunes to the low water line reaching sediment depths down to 5 m below sediment surface. Spatial variations in pore water residence time, salinity, and organic matter availability lead to steep redox and nutrient gradients. Vertical and horizontal differences in the microbial community indicate the influence of these gradients and salinity on the community structure. Modeled seawater flux through the USP and freshwater flux through the tube are on average 2.8 and 0.75 m3 per day and meter of shoreline, respectively. Furthermore, ridge sediments at the lower beach discharge seawater at rates of 0.5 and 1.0 m3 per day and meter of shoreline towards the runnel and seaside, respectively. Applying seawater and freshwater fluxes and representative nutrient concentrations for the discharge zones, nutrient fluxes to adjacent nearshore waters are 117 mmol NH4+, 55 mmol PO43 − and 575 mmol Si(OH)4 per day and meter of shoreline. We propose that this nutrient efflux triggers growth of microphytobenthos on sediment surfaces of the discharge zone. A first comparison of nutrient discharge rates of the beach site with a nearby sandy backbarrier tidal flat margin indicates that the beach system might be of less importance in supplying recycled nutrients to nearshore waters than the backbarrier tidal flat area.

Cycling of redox-sensitive elements in a sandy subterranean estuary of the southern North Sea

The cycling of metals and sulfur plays an important role in beach sediments. We studied the redox-sensitive metals Mn, Fe, U, Re, Mo, and V, in relation to salinity, organic matter-, and sulfur cycling within the subterranean estuary of a barrier island sand beach on Spiekeroog Island, Northern Germany. Pore water samples were obtained along a cross-shore transect down to 5m below the sediment surface.Redox conditions range from oxic, close to the base of the dune, to sub- to anoxic towards the low water line. We demonstrate that biogeochemical processes alter not only the pore water concentrations of the trace metals, but are also reflected by the O isotope- and to a minor degree the S isotope composition of dissolved SO42−. The deviations from conservative mixing between terrestrial and marine endmembers influence trace metal fluxes into the ocean via submarine groundwater discharge. Redox reactions may be accelerated by the presence of dissolved reactive Mn, which we detected in shallow suboxic pore waters. Changes in the O isotope composition of SO42− indicate a cryptic S cycle in the suboxic zone that is fueled by the cycling of Fe and Mn.Seawater circulation through sediments of the upper beach (duneward part of the intertidal zone) removes U and V from solution, but serves as a source for Mn, Fe, Re, and Mo to the ocean. Pore water discharging from a berm close to the low water line exhibits lower U, V, and Re concentrations than adjacent seawater. This part of the beach thus serves as a sink for U, V, and Re, but as a source for Mn, Fe, and Mo. No significant Mo depletion is found in the pore water, due to the lack of dissolved sulfide. Net flux rates from the subterranean estuary into the ocean are estimated to be 185mmol for Fe, 48mmol for Mn, 8.3μmol for Mo, −24.7nmol for Re, −8.6μmol for U, and −24μmol for V per day and meter of shore line. These fluxes include freshwater flux from the island's freshwater lens and seawater circulation through the beach face. The subterranean estuary therefore serves as V, U, and Re sink, but as a source for Fe, Mn, and Mo to adjacent seawater.A first comparison of net fluxes of dissolved metals from the Spiekeroog beach system with the island's backbarrier tidal flat margins indicates that the tidal flat area might be of greater importance for the supply or removal of metals to/from the North Sea.

Three new species of Eugenia (Myrtaceae) from Brazilian Amazonia

Three new species of Eugenia occurring in Brazilian Amazonian rainforest are described and illustrated: Eugenia kerianthera, Eugenia caducipetala and Eugenia marleneae. Eugenia kerianthera is related to Eugenia yasuniana, from which it is distinguished by its deltoid bracts and setaceous bracteoles, persistent and widely deltoid sepals, and oblong to obovate petals. Eugenia caducipetala is similar to Eugenia exaltata but is differentiated by leaves with flat margins and midvein convex adaxially. Eugenia marleneae is similar to Eugenia gomesiana and Eugenia trinervia, being distinguished from the first by its orbicular bracteoles and from the second by its fasciculate inflorescences. Phenological data, geographical distributions and further comparisons with morphologically similar species are provided.

Carbon, nutrient and trace metal cycling in sandy sediments: A comparison of high-energy beaches and backbarrier tidal flats

In order to evaluate the importance of coastal sandy sediments and their contribution to carbon, nutrient and metal cycling we investigated two beach sites on Spiekeroog Island, southern North Sea, Germany, and a tidal flat margin, located in Spiekeroog's backbarrier area. We also analyzed seawater and fresh groundwater on Spiekeroog Island, to better define endmember concentrations, which influence our study sites.Intertidal sandy flats and beaches are characterized by pore water advection. Seawater enters the sediment during flood and pore water drains out during ebb and at low tide. This pore water circulation leads to continuous supply of fresh organic substrate to the sediments. Remineralization products of microbial degradation processes, i.e. nutrients, and dissolved trace metals from the reduction of particulate metal oxides, are enriched in the pore water compared to open seawater concentrations.The spatial distribution of dissolved organic carbon (DOC), nutrients (PO43−, NO3−, NO2−, NH4+, Si(OH)4 and total alkalinity), trace metals (dissolved Fe and Mn) as well as sulfate suggests that the exposed beach sites are subject to relatively fast pore water advection, which leads to organic matter and oxygen replenishment. Frequent pore water exchange further leads to comparatively low nutrient concentrations. Sulfate reduction does not appear to play a major role during organic matter degradation. High nitrate concentrations indicate that redox conditions are oxic within the duneward freshwater influenced section, while ammonification, denitrification, manganese and iron reduction seem to prevail in the ammonium-dominated seawater circulation zone. In contrast, the sheltered tidal flat margin site exhibits a different sedimentology (coarser beach sands versus finer tidal flat sands) and nutrients, dissolved manganese and DOC accumulate in the pore water. Ammonium is the dominant pore water nitrogen species and intense sulfate reduction leads to the formation of sulfide, which precipitates dissolved iron as iron sulfide. These findings are due to slower advective pore water exchange in the tidal flat sediments. This study illustrates how different energy regimes affect biogeochemical cycling in intertidal permeable sediments.

Biogeochemistry of dissolved organic matter in an anoxic intertidal creek bank

Seawater circulation in permeable coastal sediments is driven by tidal changes in hydraulic gradients. The resulting submarine groundwater discharge is a source of nutrients and dissolved organic matter (DOM) to the water column. Yet, little is known about the cycling of DOM within tidal sediments, because the molecular DOM characterization remains analytically challenging. One technique that can dissect the multitude of molecules in DOM is ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). To aim at a high resolution DOM analysis we study the seasonal turnover and marine and terrestrial sources of DOM in an intertidal creek bank of the southern North Sea down to 3m depth and link the biogeochemical processes to FT-ICR-MS data and the analyses of inorganic porewater chemistry, δ13C of solid-phase extracted dissolved organic carbon (SPE-DOC), dissolved black carbon (DBC) and dissolved carbohydrates (DCHO). Increasing concentrations of dissolved Fe, Mn, P, total alkalinity, dissolved nitrogen, DOC and a concomitant decrease of sulfate along the seawater circulation path from the upper tidal flat to the tidal flat margin indicate continuous microbial activity. The relative increase of Si concentrations, unsaturated aliphatics, peptide molecular formulae and isotopically more 13C-enriched SPE-DOC towards the tidal flat margin suggests that remineralization processes mobilize DOM from buried algal (diatoms) and microbial biomass. Porewater in sediments <100cm depth contains 13C-depleted SPE-DOC and highly unsaturated compounds which are probably derived from eroded peats, suggesting rapid removal of bioavailable marine DOM such as DCHO from the water column and selective enrichment of terrestrial DOM. DBC concentrations are highest in the discharging porewater close to the tidal creek suggesting that the intertidal flat is an important DBC source to the coastal ocean. Porewater DOM accumulating at the low water line is enriched in N and S. We hypothesize that this is partly due to DOM reacting with dissolved sulfide and ammonium which may increase the refractory character of the DOM, hence making it less bioavailable for in situ active microbes.

Una nueva especie de helecho del género Danaea (Marattiales: Marattiaceae) endémica de Costa Rica

Danaea tuomistoana A. Rojas (Marattiaceae) is described and illustrated as a new species endemic to Costa Rica; it differs from D. crispa Endres et Richb. by a truncate blade, and by the pinnae, which are 2/5-1/2 incised, cuneated at the base and with a flat margin. The range of D. erecta H. Tuomisto & R.C. Moran in Costa Rica is expanded with a new locality in Puntarenas (8 degrees 57'15" N-82 degrees 50'1" W, 1,500-1,580 masl).

Dissolved inorganic nitrogen concentrations in an estuarine tidal flat

Tay, H.W., Bryan, K.R. and Pilditch, C.A., 2013. Dissolved inorganic concentrations in an estuarine tidal flatWaikareao Estuary is a shallow tidally dominated estuary located in Tauranga Harbour, New Zealand. The primary aim of this study was to determine the seasonal variations in nitrate and ammonium concentration in sediment pore-waters on a tidal flat margin in the Waikareao Estuary. Vertical profiles of sediment pore-water were sampled 5, 10, 25, 50 and 75-cm depths to provide snapshots of nutrient concentration at different times of the year. Pore-water recycling processes were an important source of dissolved inorganic nitrogen (DIN) to the estuary during low tide with greatest concentrations observed in mid-winter and summer. Pore-water profiles showed ammonium as the dominant form of DIN in the wells. Nitrate concentration was higher in surface sediment and ammonium dominated the mid-depth regions (25–50 cm). The vertical stratification of the DIN in the wells suggested oxidation at the surface produced higher nitrate concentrations while at deeper depths, ammonification and dissimilatory nitrate reduction to ammonium produced higher ammonium concentrations. Long-term monitoring by the Regional Council of Kopurereroa Stream which discharges into Waikareao Estuary, showed higher nitrate concentrations than the tidal flat wells and other monitored sites. This further highlights that the primary source of nitrate into estuaries is through freshwater discharge and ammonium is dominated by sediment recycling processes.