Examining the influence of regional‐scale variability in temperature and light availability on the depth distribution of subtidal kelp forests

Turbid coral reefs experience high suspended sediment loads and low-light conditions that vertically compress the maximum depth of reef growth. Although vertical reef compression is hypothesized to further decrease available coral habitat as environmental conditions on reefs change, its causative processes have not been fully quantified. Here, we present a high-resolution time series of environmental parameters known to influence coral depth distribution (light, turbidity, sedimentation, currents) within reef crest (2–3 m) and reef slope (7 m) habitats on two turbid reefs in Singapore. Light levels on reef crests were low [mean daily light integral (DLI): 13.9 ± 5.6 and 6.4 ± 3.0 mol photons m–2 day–1 at Kusu and Hantu, respectively], and light differences between reefs were driven by a 2-fold increase in turbidity at Hantu (typically 10–50 mg l–1), despite its similar distance offshore. Light attenuation was rapid (KdPAR: 0.49–0.57 m–1) resulting in a shallow euphotic depth of <11 m, and daily fluctuations of up to 8 m. Remote sensing indicates a regional west-to-east gradient in light availability and turbidity across southern Singapore attributed to spatial variability in suspended sediment, chlorophyll-a and colored dissolved organic matter. Net sediment accumulation rates were ∼5% of gross rates on reefs (9.8–22.9 mg cm–2 day–1) due to the resuspension of sediment by tidal currents, which contribute to the ecological stability of reef crest coral communities. Lower current velocities on the reef slope deposit ∼4 kg m2 more silt annually, and result in high soft-sediment benthic cover. Our findings confirm that vertical reef compression is driven from the bottom-up, as the photic zone contracts and fine silt accumulates at depth, reducing available habitat for coral growth. Assuming no further declines in water quality, future sea level rise could decrease the depth distribution of these turbid reefs by a further 8–12%. This highlights the vulnerability of deeper coral communities on turbid reefs to the combined effects of both local anthropogenic inputs and climate-related impacts.

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Depth-distribution of lake benthic diatom assemblages in relation to light availability and substrate: implications for paleolimnological studies

Journal of Paleolimnology ◽

10.1007/s10933-020-00139-9 ◽

2020 ◽

Vol 64 (3) ◽

pp. 315-334 ◽

Cited By ~ 1

Author(s):

Andrea M. Hofmann ◽

Juergen Geist ◽

Lena Nowotny ◽

Uta Raeder

Keyword(s):

Depth Distribution ◽

Light Availability ◽

Benthic Diatom ◽

Diatom Assemblages

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Nutrient availability and senescence spatially structure the dynamics of a foundation species

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2105135118 ◽

2021 ◽

Vol 119 (1) ◽

pp. e2105135118

Author(s):

Tom W. Bell ◽

David A. Siegel

Keyword(s):

Population Dynamics ◽

Physiological Condition ◽

Regional Scale ◽

Photosynthetic Pigment ◽

Terrestrial Ecosystems ◽

Plant Population ◽

Environmental Drivers ◽

Kelp Forests ◽

Plant Population Dynamics ◽

Wide Range

Disentangling the roles of the external environment and internal biotic drivers of plant population dynamics is challenging due to the absence of relevant physiological and abundance information over appropriate space and time scales. Remote observations of giant kelp biomass and photosynthetic pigment concentrations are used to show that spatiotemporal patterns of physiological condition, and thus growth and production, are regulated by different processes depending on the scale of observation. Nutrient supply was linked to regional scale (>1 km) physiological condition dynamics, and kelp forest stands were more persistent where nutrient levels were consistently high. However, on local scales (<1 km), internal senescence processes related to canopy age demographics determined patterns of biomass loss across individual kelp forests despite uniform nutrient conditions. Repeat measurements of physiology over continuous spatial fields can provide insights into complex dynamics that are unexplained by the environmental drivers thought to regulate abundance. Emerging remote sensing technologies that provide simultaneous estimates of abundance and physiology can quantify the roles of environmental change and demographics governing plant population dynamics for a wide range of aquatic and terrestrial ecosystems.

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Applications of SIMS to electronic materials and devices

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100133047 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1682-1683

Author(s):

S.F. Corcoran

Keyword(s):

Depth Distribution ◽

Secondary Ion Mass Spectrometry ◽

Semiconductor Device ◽

Electronic Materials ◽

Profile Analysis ◽

Semiconductor Industry ◽

Small Diameter ◽

Depth Resolution ◽

Detection Sensitivity

Over the past decade secondary ion mass spectrometry (SIMS) has played an increasingly important role in the characterization of electronic materials and devices. The ability of SIMS to provide part per million detection sensitivity for most elements while maintaining excellent depth resolution has made this technique indispensable in the semiconductor industry. Today SIMS is used extensively in the characterization of dopant profiles, thin film analysis, and trace analysis in bulk materials. The SIMS technique also lends itself to 2-D and 3-D imaging via either the use of stigmatic ion optics or small diameter primary beams.By far the most common application of SIMS is the determination of the depth distribution of dopants (B, As, P) intentionally introduced into semiconductor materials via ion implantation or epitaxial growth. Such measurements are critical since the dopant concentration and depth distribution can seriously affect the performance of a semiconductor device. In a typical depth profile analysis, keV ion sputtering is used to remove successive layers the sample.

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Fluorescence effects in quantitative microprobe analysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100134533 ◽

1990 ◽

Vol 48 (2) ◽

pp. 188-189

Author(s):

S.J.B. Reed

Keyword(s):

Microprobe Analysis ◽

Depth Distribution ◽

Exciting Radiation ◽

Primary Radiation ◽

List Type ◽

Type Number ◽

Computing Power ◽

X Ray ◽

Fluorescent Radiation

Characteristic fluorescenceThe theory of characteristic fluorescence corrections was first developed by Castaing. The same approach, with an improved expression for the relative primary x-ray intensities of the exciting and excited elements, was used by Reed, who also introduced some simplifications, which may be summarized as follows (with reference to K-K fluorescence, i.e. K radiation of element ‘B’ exciting K radiation of ‘A’):1.The exciting radiation is assumed to be monochromatic, consisting of the Kα line only (neglecting the Kβ line).2.Various parameters are lumped together in a single tabulated function J(A), which is assumed to be independent of B.3.For calculating the absorption of the emerging fluorescent radiation, the depth distribution of the primary radiation B is represented by a simple exponential.These approximations may no longer be justifiable given the much greater computing power now available. For example, the contribution of the Kβ line can easily be calculated separately.

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A New Numerical Model for Electron-Probe Analysis at High Depth Resolution

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010016491x ◽

1996 ◽

Vol 54 ◽

pp. 490-491

Author(s):

P.-F. Staub ◽

C. Bonnelle ◽

F. Vergand ◽

P. Jonnard

Keyword(s):

Electron Probe ◽

Surface Segregation ◽

Depth Distribution ◽

Computing Time ◽

Depth Resolution ◽

Physical Parameters ◽

Electron Probe Analysis ◽

Interface Phases ◽

Excitation Conditions ◽

High Depth

Characterizing dimensionally and chemically nanometric structures such as surface segregation or interface phases can be performed efficiently using electron probe (EP) techniques at very low excitation conditions, i.e. using small incident energies (0.5<E0<5 keV) and low incident overvoltages (1<U0<1.7). In such extreme conditions, classical analytical EP models are generally pushed to their validity limits in terms of accuracy and physical consistency, and Monte-Carlo simulations are not convenient solutions as routine tools, because of their cost in computing time. In this context, we have developed an intermediate procedure, called IntriX, in which the ionization depth distributions Φ(ρz) are numerically reconstructed by integration of basic macroscopic physical parameters describing the electron beam/matter interaction, all of them being available under pre-established analytical forms. IntriX’s procedure consists in dividing the ionization depth distribution into three separate contributions:

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Koreans across the Sea: Migration of Laborers to the Metropole, 1910–1937

European Journal of Korean Studies ◽

10.33526/ejks.20191901.161 ◽

2019 ◽

pp. 161-200

Author(s):

Mikwi Cho

Keyword(s):

Capital Accumulation ◽

Regional Scale ◽

Living Conditions ◽

Colonial Period ◽

Global City ◽

Japanese Empire ◽

Chain Migration ◽

Free Mobility

This paper is concerned with Korean farmers who were transformed into laborers during the Korean colonial period and migrated to Japan to enhance their living conditions. The author’s research adopts a regional scale to its investigation in which the emergence of Osaka as a global city attracted Koreans seeking economic betterment. The paper shows that, despite an initial claim to permit the free mobility of Koreans, the Japanese empire came to control this mobility depending on political, social, and economic circumstances of Japan and Korea. For Koreans, notwithstanding poverty being a primary trigger for the abandonment of their homes, the paper argues that their migration was facilitated by chain migration and they saw Japan as a resolution to their economic hardships in the process of capital accumulation by the empire.

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