Difference In Depth Profiles Research Articles

Eroding diversity away: Impacts of a tetrapod breakwater on a subtropical coral reef

Abstract Artificial barriers for coastal protection have been deployed across numerous tropical and subtropical islands in the Pacific, including Okinawa Island, southern Japan, where artificial defences have been installed along a large part of the coastline. Although artificial barriers can lead to beach narrowing or loss and can exacerbate erosion, their effects on coral reef ecosystems remain understudied. This study investigated the impact of a tetrapod breakwater in Ogimi Village, Okinawa Island, Japan, comparing the area affected by the presence of the barrier with a nearby natural coastline, and examining differences in physical parameters (depth profiles, sediment granulometry, and erosion on plaster balls) and benthic community composition. Significant differences in depth profiles, sediment granulometry, and erosion were found, suggestive of alterations in water energy levels (lower than controls on the landward side of the barrier, and higher on the seaward side). The benthic community was also clearly affected, with almost no living corals growing over the blocks or in their proximity. Overall, the data show how breakwaters can affect the physical environment and benthic communities in a subtropical coral reef ecosystem, with negative consequences for coral survival.

Patterns of fish utilisation in a tropical Indo-Pacific mangrove-coral seascape, New Caledonia.

Mangrove forests are important habitats for fish. However, their utilisation by fish, and the specific values they confer, are still not fully understood. This study describes how fish use mangrove forests in an Indo-Pacific mangrove-coral reef seascape. Sampling was conducted using underwater video cameras (UVCs) to describe spatial and temporal variations in fish assemblages across a small-scale (~ 2.5 km2) system, and over the tidal and lunar cycle. UVCs were deployed in the two main component habitats of mangrove forests: at the mangrove forest edge, and inside the forest (5 m from the forest edge), to establish patterns of utilisation of fish across the tidal and lunar cycle. Proximity to coral reefs had a strong influence on the mangrove fish community, as most fish recorded were reef-associated. Juveniles of 12 reef species were observed, including two species classified as vulnerable on the IUCN list, and one endemic species. Fish assemblages on the mangrove edge differed significantly from those inside the forest. Most fish utilised the forest edge, with few species making regular use of in-forest habitats, supporting the contention that most fish species remain on the edge and potentially retreat into the forest for opportunistic feeding, or when threatened by larger predators. Species-specific patterns of utilisation varied across the tidal and lunar cycle. Small differences in depth profiles and substrate across the small-scale system had a significant effect on fish assemblages, highlighting the importance of accounting for spatial heterogeneity in these factors. These data provide important information for managers to implement adequate conservation strategies that include broader interconnected habitat mosaics.

Benthic microalgal variability associated with peritidal stromatolite microhabitats along the South African coast

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 82:253-264 (2019) - DOI: https://doi.org/10.3354/ame01895 Benthic microalgal variability associated with peritidal stromatolite microhabitats along the South African coast Ross-Lynne A. Weston1,*, Renzo Perissinotto1, Gavin M. Rishworth1, Paul-Pierre Steyn2 1DST/NRF Research Chair in Shallow Water Ecosystems, Institute for Coastal and Marine Research (CMR), Nelson Mandela University, Port Elizabeth 6031, South Africa 2Department of Botany, Nelson Mandela University, Port Elizabeth 6031, South Africa *Corresponding author: rosslynne.weston747@gmail.com ABSTRACT: Stromatolites, structures formed with the input of microorganisms such as cyanobacteria, can be traced back to the Precambrian. Many modern marine stromatolites have a coarser internal structure and host a diverse eukaryotic community. Known as eualgal-cyanobacterial stromatolites, these formations are likely a result of the higher abundance of larger sediment particles from the biomineralisation of skeletal material. However, it is unclear how eukaryotic microalgae have contributed towards modern stromatolite formation. Therefore, the aim of this study was to investigate how the microalgal community contributes towards the differences in depth profiles and layering observed amongst mesofabric structures in stromatolite pools along the Port Elizabeth coastline in South Africa. This goal was achieved by comparing the proportional abundances of each of the major microalgal classes (cyanobacteria, bacillariophytes and chlorophytes) between the different mesofabric types and depth profiles. Clear variability in terms of proportional abundance was apparent between microhabitats and with depth. Coarser, irregular types had a higher bacillariophyte biomass than smoother types. This difference is likely a consequence of the greater efficiency of bacillariophytes in trapping larger sediment particles. Eukaryotic microalgae (specifically bacillariophytes) are highlighted as important ecosystem engineers in these modern ecosystems. KEY WORDS: Microbialites · Mesofabric types · Niches · Microphytobenthos · Ecosystem engineering Full text in pdf format Supplementary material PreviousNextCite this article as: Weston RLA, Perissinotto R, Rishworth GM, Steyn PP (2019) Benthic microalgal variability associated with peritidal stromatolite microhabitats along the South African coast. Aquat Microb Ecol 82:253-264. https://doi.org/10.3354/ame01895 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 82, No. 3. Online publication date: January 21, 2019 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2019 Inter-Research.

Measurement and modeling of oil slick transport

AbstractTransport characteristics of oil slicks are reported from a controlled release experiment conducted in the North Sea in June 2015, during which mineral oil emulsions of different volumetric oil fractions and a look‐alike biogenic oil were released and allowed to develop naturally. The experiment used the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) to track slick location, size, and shape for ∼8 h following release. Wind conditions during the exercise were at the high end of the range considered suitable for radar‐based slick detection, but the slicks were easily detectable in all images acquired by the low noise, L‐band imaging radar. The measurements are used to constrain the entrainment length and representative droplet radii for oil elements in simulations generated using the OpenOil advanced oil drift model. Simultaneously released drifters provide near‐surface current estimates for the single biogenic release and one emulsion release, and are used to test model sensitivity to upper ocean currents and mixing. Results of the modeling reveal a distinct difference between the transport of the biogenic oil and the mineral oil emulsion, in particular in the vertical direction, with faster and deeper entrainment of significantly smaller droplets of the biogenic oil. The difference in depth profiles for the two types of oils is substantial, with most of the biogenic oil residing below depths of 10 m, compared to the majority of the emulsion remaining above 10 m depth. This difference was key to fitting the observed evolution of the two different types of slicks.

Investigation into mixing in the shallow floodplain Poyang Lake (China) using hydrological, thermal and isotopic evidence.

Although mixing in lakes has significant environmental and ecological implications, knowledge of mixing dynamics for shallow floodplain lakes has received little attention. In this study, hydrological, thermal and isotopic investigations were undertaken to provide evidence for the mixing in the large, shallow floodplain Poyang Lake (China). Depth profiles of water velocity, water temperature and stable hydrogen and oxygen isotope compositions were measured throughout the lake, with results showing that the water velocity differences in depth profiles are generally less than ∼0.2 m/s, indicating weak stratification. Although water temperature differences of up to ∼2 °C are observed occasionally, Poyang Lake appears to have isothermal mixed layers from the epilimnion to the hypolimnion, attributed to the presence of mostly small temperature differences (<1 °C). Additionally, isotope compositions reveal that the lake's water columns are almost homogeneous during various water-level periods. Relative to many lakes exhibiting either no mixing or partial mixing, Poyang Lake appears to be fully mixing on a seasonal basis, depending on hydrological forcings within the lake rather than meteorological conditions. The current study will help to improve our knowledge of water flow patterns and pollutant transport in Poyang Lake and other similar floodplain lakes.

SU‐F‐T‐449: Dosimetric Comparison of Acuros XB, Adaptive Convolve in Intensity Modulated Radiotherapy for Head and Neck Cancer

Purpose:There have been several publications focusing on dose calculation in lung for a new dose calculation algorithm of Acuros XB (AXB). AXB could contribute to dose calculation for high‐density media for bone and dental prosthesis rather than in lung. We compared the dosimetric performance of AXB, Adaptive Convolve (AC) in head and neck IMRT plans.Methods:In a phantom study, the difference in depth profile between AXB and AC was evaluated using Kodak EDR2 film sandwiched with tough water phantoms. 6 MV x‐ray using the TrueBeam was irradiated. In a patient study, 20 head and neck IMRT plans had been clinically approved in Pinnacle3 and were transferred to Eclipse. Dose distribution was recalculated using AXB in Eclipse while maintaining AC‐calculated monitor units and MLC sequence planned in Pinnacle. Subsequently, both the dose‐volumetric data obtained using the two different calculation algorithms were compared.Results:The results in the phantom evaluation for the shallow area ahead of the build‐up region shows over‐dose for AXB and under‐dose for AC, respectively. In the patient plans, AXB shows more hot spots especially around the high‐density media than AC in terms of PTV (Max difference: 4.0%) and OAR (Max. difference: 1.9%). Compared to AC, there were larger dose deviations in steep dose gradient region and higher skin‐dose.Conclusion:In head and neck IMRT plans, AXB and AC show different dosimetric performance for the regions inside the target volume around high‐density media, steep dose gradient regions and skin‐surface. There are limitations in skin‐dose and complex anatomic condition using even inhomogeneous anthropomorphic phantom Thus, there is the potential for an increase of hot‐spot in AXB, and an underestimation of dose in substance boundaries and skin regions in AC.

Enamel roughness and depth profile after phosphoric acid etching of healthy and fluorotic enamel

Dental fluorosis requires aesthetic treatment to improve appearance and etching of enamel surfaces with phosphoric acid is a key step for adhesive restorations. The aim of this study was to evaluate surface roughness and a depth profile in healthy and fluorotic enamel before and after phosphoric acid etching at 15, 30 and 60 seconds. One hundred and sixty enamel samples from third molars with no fluorosis to severe fluorosis were evaluated by atomic force microscopy. Healthy enamel showed a statistically significant difference (p < 0.05) between mean surface roughness at 15 seconds (180.3 nm), 30 seconds (260.9 nm) and 60 seconds (346.5 nm); depth profiles revealed a significant difference for the 60 second treatment (4240.2 nm). For mild fluorosis, there was a statistically significant difference (p < 0.05) between mean surface roughness for 30 second (307.8 nm) and 60 second (346.6 nm) treatments; differences in depth profiles were statistically significant at 15 seconds (2546.7 nm), 30 seconds (3884.2 nm) and 60 seconds (3612.1 nm). For moderate fluorosis, a statistically significant difference (p < 0.05) was observed for surface roughness for 30 second (324.5 nm) and 60 second (396.6 nm) treatments. Surface roughness and depth profile analyses revealed that the best etching results were obtained at 15 seconds for the no fluorosis and mild fluorosis groups, and at 30 seconds for the moderate fluorosis group. Increasing the etching time for severe fluorosis decreased surface roughness and the depth profile, which suggests less micromechanical enamel retention for adhesive bonding applications.

Determining factor of effective work function in metal/bi-layer high-k gate stack structure studied by photoemission spectroscopy

We have demonstrated the determining factor of effective work function in TiN/HfO2/Al2O3/SiO2 gate stack structures by photoemission spectroscopy with synchrotron radiation. Difference in depth profiles indicate that the Si layer inserted at the HfO2/Al2O3 interface suppresses diffusion of Al atoms into the HfO2 layer after annealing, resulting in keeping magnitude of the high-k/SiO2 interface dipole. However, it is found that the increase of the effective work function cannot be explained only by the interface dipole model. We suggest that oxidation of the TiN metal electrode due to oxygen diffusion from the HfO2 layer is one of the most important factors.

Nitric–phosphoric acid etching effects on the surface chemical composition of CdTe thin film

Nitric–phosphoric (NP) acid etching has been regarded as one of the most effective methods for the formation of low resistance back contact with the metal electrode in CdTe based photovoltaic cells. We studied CdTe back surfaces and the changes with time of exposure to NP acid with x-ray photoelectron spectroscopy (XPS), and atomic force microscopy. Strong etching dependence on the back surface chemical composition, and surface roughness, was observed. In order to study the effect of the NP acid etching on surface degradation, the sample was left in open ambient condition for three weeks and XPS measurement in combination with ion sputtering was performed on unetched and highly etched parts. The difference in depth profiles of the NP acid etched and unetched CdTe surface has been discussed.

Comparison of the depth profiles of water and water-binding substances in the stratum corneum determined in vivo by Raman spectroscopy between the cheek and volar forearm skin: effects of age, seasonal changes and artificial forced hydration

Dermatologists and cosmetic scientists are becoming increasingly interested in stratum corneum (SC) hydration because the SC plays an important role in keeping the skin surface soft and smooth. However, conventional in vivo noninvasive methods do not provide direct information about the depth profiles of water content or SC components that hold water. To study the depth profiles of water and SC components in vivo by Raman spectroscopy, and to analyse the changes due to age, anatomical location, season and water application. In vivo Raman spectra of the skin of the cheek and the volar forearm were obtained from 50 healthy Japanese volunteers of different ages (age range 22-76 years) with a confocal Raman spectrometer. The depth-dependent profiles of water and of SC water-binding components were calculated from the respective Raman spectra. The depth profile of the SC water content was observed in a pattern ranging from around 30% (water/wet tissue) at the outermost layer of the SC to about 70% at the deeper living layer. Although the water content at a depth of 10-30 microm in the forearm skin tended to be lower in older subjects than in younger subjects, no such difference was found in the much thinner SC of the cheek. Moreover, there was no seasonal difference in depth profile of water content from the mid part of the SC to an 80-microm depth from the skin surface both in the cheek and in the forearm. The water content of all the evaluated SC components showed a gradual decrease from the surface to deeper portions. The mean amounts of lactate in the forearm skin and cholesterol in the cheek skin were significantly higher in younger subjects than in older subjects. In contrast, the levels of free amino acids and trans-urocanic acid were higher in the forearm skin of older subjects than in younger subjects. The relative amounts of urea and lactate were the highest in summer, when that of trans-urocanic acid was the lowest. Prolonged water application on the forearm skin even for 90 min resulted in a remarkable increase in water content throughout the SC, even reaching the granular layer, which was only gradually released from the upper part of the SC after discontinuation of the hydration procedure. Our present findings suggest that changes in the concentration depth profiles of water, free amino acids and lipids in the skin depend on age, anatomical site and season. These findings indicate the important roles played by various water-holding substances in the SC in the regulation of SC water content.

Seasonal changes of submerged macrophyte community with different depth profile in a calm bay of Lake Biwa, Japan

The structure of a submerged macrophyte community (vegetation cover, species richness and species composition) and the seasonal changes were investigated at the littoral zone (< 6 m deep) of a calm bay in Northern Basin of Lake Biwa, Japan, where the transparency is high and no waterfowl grazers exist. To evaluate the effect of a small difference in depth profile on the community structure, the vegetation map of 35 m-belt transect (4 m wide) was made monthly at two sites (30 m apart) between March and November 1997. In total, the same 11 species were observed in the two sites, including two alien species, Egeria densa and Elodea nuttallii, and an endemic species, Vallisneria biwaensis. There was no significant difference in species richness in a census between the two sites. The species zonation was unclear in both sites: various mixed species patches were found throughout the study period. There were differences in the growth patterns of five species between the two sites. In a calm and clear-water littoral zone, where there is no disturbance by wave action, a small difference in depth profile can affect the growth patterns of several macrophyte species and then affect the three-dimensional structure of the macrophyte community, which can be a crucial determinant of the habitat structure of small aquatic animals.

Behaviour of settlement-stage larvae of fishes with an estuarine juvenile phase: in situ observations in a warm-temperate estuary

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 242:205-214 (2002) - doi:10.3354/meps242205 Behaviour of settlement-stage larvae of fishes with an estuarine juvenile phase: in situ observations in a warm-temperate estuary Thomas Trnski* Ichthyology, Division of Vertebrate Zoology, Australian Museum, 6 College Street, Sydney, New South Wales 2010, and Department of Environmental Sciences, University of Technology, PO Box 123, Broadway, Sydney, New South Wales 2007, Australia *Correspondence address. E-mail: tomt@austmus.gov.au ABSTRACT: Observations of behaviour were made on a total of 103 settlement-stage larvae (9 to 15 mm standard length [SL]) of 4 species of estuary-dependent fishes in Lake Macquarie, a barrier estuary on the central coast of New South Wales, Australia. Larvae were released at mid-depth over deep water or within sight of settlement habitat, and their behaviour was observed by SCUBA divers. Average near-surface swimming speed was 6.4 cm s-1 (7.1 body lengths [BL] s-1) for Acanthopagrus australis, 6.4 cm s-1 (6.5 BL s-1) for Rhabdosargus sarba, 10.9 cm s-1 (10.8 BL s-1) for Pagrus auratus (all family Sparidae) and 12.5 cm s-1 (11.2 BL s-1) for Girella tricuspidata (Girellidae). These speeds were faster than previously recorded for temperate fish larvae. It is hypothesised that body morphology determines swimming ability. At these speeds, the larvae are faster than ambient currents. The majority of larvae of all species swam in a directional (non-random) manner, but there was no evidence that the larvae were orienting to the shoreline or the sun. There were species-specific differences in depth profile: the 3 species that settle in seagrass beds preferentially swam near the surface; P. auratus, which settles over soft bottoms, preferentially swam to the bottom. Swimming near the surface in Lake Macquarie brings larvae into strong wind-driven surface currents that carry them to a shoreline and settlement habitat. Larvae of only G. tricuspidata (1 of 3 species that settle in seagrass) were rarely observed to settle when they were released within sight of a seagrass margin. KEY WORDS: Larva · Fish · Behaviour · Swimming speed · Settlement · Orientation · Acanthopagrus · Girella · Pagrus · Rhabdosargus Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 242. Online publication date: October 25, 2002 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2002 Inter-Research.

Electroluminescence properties of electropolymerized poly (para-phenylene) films by means of electrochemical oxidation and reduction

We investigated electroluminescence (EL) properties of electropolymerized poly-p-phenylene (PPP) films formed by means of electro-oxidative and electro-reductive methods. Electro-oxidatively polymerized PPP (O-PPP) and electro-reductively polymerized PPP (R-PPP) clearly demonstrated different light emitting behavior. In the case of electro-oxidative PPP, the intensity of light emission decreased with increasing quantity of polymerization charge, whereas with electro-reductive PPP, it increased with increasing quantity of polymerization charge. These different types of behavior of the two kinds of PPP films suggested the difference in depth profile of the regularity of molecular structures formed by the two different methods.

Localization of the constituent depth profile near Al-Sn alloy surface

Micro-beam Rutherford backscattering spectroscopy(M-RBS) was used to scan and profile the Snconcentration of an Al-Sn (30% wt) alloy surface. Two separate phase-regions with Al-rich and Sn-rich surfaces were examined. Differences in depth profile between the different phase-regions and between before and after ion bombardment for various phase-regions were found. These data suggest that the surface depth profile is not homogeneous in the whole surface region for two-phase alloy.

A comparative study of the zooplankton in two adjacent embayments, Port Phillip and Westernport Bays, Australia

We report on a year's study of spatial and seasonal patterns of zooplankton abundance in Port Phillip and Westernport Bays, July 1982 to August 1983. These two bays, closely adjacent on the southern coast of Victoria, Australia, differ in several respects: Port Phillip is a nearly landlocked bay with a broad basin, while Westernport is an open tidal embayment with extensive mud and seagrass banks. Both bays have a resident zooplankton fauna distinct from that of Bass Strait. Although these resident communities have many species in common, patterns of abundance and dominance are quite different. We found that the holoplankton of Port Phillip was about half copepods, mostly Paracalanus indicus, with 23% Caldocera and 21% larvaceans. Westernport Bay zooplankton was dominated by Acartia tranteri, with no resident cladoceran fauna. Bass Strait species were more often found in Westernport than in Port Phillip Bay, but the resident community of Port Phillip Bay was more similar to that of Bass Strait than to that of Westernport. Although this study was undertaken in an exceptionally dry year, the available historical data show that the overall patterns found in 1982–1983 are typical for these bays. The differences in community composition probably relate to differences in depth profile, predator abundance, and suspended matter between the bays.