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FIGURE 10. Paraselenia gratiosa A in New Ecological Observations and Occurrence for Asteroidea and Echinoidea in Hong Kong

FIGURE 10. Paraselenia gratiosa A. In situ under normal conditions. B. Individual with spines covered by Ophiactis brittle stars. Photographer: Sam King Fung Yiu.

FIGURE 11 in New Ecological Observations and Occurrence for Asteroidea and Echinoidea in Hong Kong

FIGURE 11. Stomopneustes variolaris Aquarium observation of a living individual. Photographer: Sam King Fung Yiu.

FIGURE 41. Gymnanthenea difficilis. Color variation. A in New Ecological Observations and Occurrence for Asteroidea and Echinoidea in Hong Kong

FIGURE 41. Gymnanthenea difficilis. Color variation. A. In situ, red color variant. B. In situ, mottled color variant. C. In situ, orange-white color variant. Photographer: Sam King Fung Yiu.

FIGURE 9. Heliocidaris crassispina. A in New Ecological Observations and Occurrence for Asteroidea and Echinoidea in Hong Kong

FIGURE 9. Heliocidaris crassispina. A. In situ observation of H. crassispina with strands of white tissue on spines. B. Observation of this species with jellyfish caught on spines. Photographer: Sam King Fung Yiu.

FIGURE 40. Culcita novaeguineae A in New Ecological Observations and Occurrence for Asteroidea and Echinoidea in Hong Kong

FIGURE 40. Culcita novaeguineae A. In situ showing abactinal surface. B. In situ, actinal surface. Photographer: Sam King Fung Yiu.

FIGURE 6. Echinothrix calamaris. Color morphotypes. A. Black and white spine form. B. White spine form. C in New Ecological Observations and Occurrence for Asteroidea and Echinoidea in Hong Kong

FIGURE 6. Echinothrix calamaris. Color morphotypes. A. Black and white spine form. B. White spine form. C. Banded spine form. Photographer: Sam King Fung Yiu.

FIGURE 4. Coelopleurus maculatus A in New Ecological Observations and Occurrence for Asteroidea and Echinoidea in Hong Kong

FIGURE 4. Coelopleurus maculatus A. In situ predation on Dendronephthya. B. Aboral view. C. Oral view. Photographer: Sam King Fung Yiu.

FIGURE 31. Astropecten polyacanthus. A in New Ecological Observations and Occurrence for Asteroidea and Echinoidea in Hong Kong

FIGURE 31. Astropecten polyacanthus. A. Abactinal view, in situ. B. Actinal view, in situ. C. Six-armed variant from Trio Island, abactinal view. D. Six armed variant actinal view. Photographer: Sam King Fung Yiu.

FIGURE 34 in New Ecological Observations and Occurrence for Asteroidea and Echinoidea in Hong Kong

FIGURE 34. Luidia longispina In situ observation, abactinal surface. Photographer: Sam King Fung Yiu.

FIGURE 8 in New Ecological Observations and Occurrence for Asteroidea and Echinoidea in Hong Kong

FIGURE 8. Echinostrephus molaris. In situ observation showing this species in a deep rock-face burrow. Photographer: Sam King Fung Yiu.

FIGURE 38. Anthenea chinensis USNM 3036. A. Abactinal. B. Abactinal-superomarginal closeup. C. Actinal. D in New Ecological Observations and Occurrence for Asteroidea and Echinoidea in Hong Kong

FIGURE 38. Anthenea chinensis USNM 3036. A. Abactinal. B. Abactinal-superomarginal closeup. C. Actinal. D. Closeup actinal surface. Scale bar: 10.0 mm=A, C. Scale bar: 5.0 mm=B, D.

FIGURE 37. Linckia and Ophidiaster armatus A in New Ecological Observations and Occurrence for Asteroidea and Echinoidea in Hong Kong

FIGURE 37. Linckia and Ophidiaster armatus A. In situ observation, O. armatus abactinal surface. B. Six rayed variant of O. armatus from Ninepin Islands, Hong Kong. C. In situ observation of L. laevigata. Photographer: A and C: Sam King Fung Yiu; B: Max Leung.

FIGURE 33. Persephonaster tenuis CASIZ 28462 in New Ecological Observations and Occurrence for Asteroidea and Echinoidea in Hong Kong

FIGURE 33. Persephonaster tenuis CASIZ 28462, vicinity of Hong Kong. A. Abactinal view. B. Closeup arm abactinal surface. C. Actinal surface. D. Closeup on actinal surface showing furrow spination and other spination.

FIGURE 2 in New Ecological Observations and Occurrence for Asteroidea and Echinoidea in Hong Kong

FIGURE 2. Eucidaris metularia. In situ image showing apical system and spines. Photographer: Josy Lai.

opencc-by-4.0Jul 2024View details →

Smoothed VLT/MUSE observations of Jupiter and Saturn

<p>Data are those used for the JGR submission: "Clouds and ammonia in the atmospheres of Jupiter and Saturn determined from a band-depth analysis of VLT/MUSE observations". Observation dates are 23rd March 2020 for Jupiter, and 6th April 2017 for Saturn.</p>

opencc-by-4.0Nov 2024View details →

Observations and Modeling Investigations of Ionospheric Response to April 23-24, 2023, G4-Class Geomagnetic Storm over Indian Sector

<p>This study explores the ionospheric response over the Indian sector to the G4-class geomagnetic storm of April 23-24, 2023. Utilizing multi-instrument observations and SAMI2 modeling, ionospheric behavior was examined during the storm's main phase (17:41 UT, April 23 - 04:03 UT, April 24) and the recovery phase (04:03 UT - 22:44 UT, April 24). During the main phase, ionosonde data from Tirunelveli showed rapid F-layer height (h’F) variations driven by westward and eastward prompt penetration electric fields (PPEFs). The westward PPEF, induced by undershielding, led to an initial decrease in h’F followed by an increase, suppressing pre-existing Equatorial Plasma Bubbles (EPBs) within two hours of the storm’s onset. Despite a late-night rise in h’F due to overshielding, no new EPB formed. The recovery phase exhibited a positive storm effect at low latitudes and a negative effect at higher latitudes, linked to disturbance dynamo electric fields (DDEFs) and thermospheric composition changes (O/N₂). Isofrequency analysis of CADI ionosonde and GNSS TEC data revealed large-scale traveling ionospheric disturbances (LSTIDs) with a ~2-hour period, ~2,450 km wavelengths, and ~340 m/s equatorward propagation speed. These LSTIDs were likely driven by atmospheric gravity waves or auroral heating. The westward DDEF suppressed the equatorial ionization anomaly (EIA) and inhibited post-sunset EPBs, while eastward DDEF increased h’F post-midnight without EPB formation. We speculate this absence might be due to a lack of seeding mechanisms. SAMI2 simulations incorporating E×B drift data reproduced several storm-time features in the main and recovery phases.</p>

opencc-zeroJul 2019View details →

Data from: The bivalved arthropod Tuzoia from the Balang Formation (Cambrian Stage 4) of Guizhou, China, and new observations on comparative species

Tuzoia is a large, bivalved Cambrian arthropod having a widespread distribution in shallow-shelf to deeper marine Lagerstätten; stratigraphically it ranges from Cambrian Series 2 through the Miaolingian Series. In the present study, three species are recognized from relatively deep-water deposits of the Balang Formation (Cambrian Stage 4) of Guizhou, South China: Tuzoia sinensis Pan, 1957, T. bispinosa Yuan et Zhao, 1999 and T. lazizhaiensis sp. nov. The new species is unique in having 6-10 small marginal spines on the dorsal margin, an inflated anterior margin with 3 short, closely spaced marginal spines. These remains, which usually occur as disarticulated valves, are inferred to be parautochthonous. One new specimen of T. lazizhaiensis shows a stalked eye and antenna. New Tuzoia material from the Kaili Biota (Cambrian: Wuliuan Stage) of Guizhou, and from the Guanshan Biota (Cambrian Stage 4) of Yunnan, China, provide additional comparative information about the genus. Some new specimens of T. bispinosa from the Kaili Biota provide information on valve morphology and palaeoecology. One specimen of T. sinensis from the Guanshan Biota provides information on the appendages, and one specimen of T. tylodesa, from the Guanshan Biota adds provides information on the trunk and appendages.

opencc-zeroDec 2015View details →

Data from: Primary production calculations for sea ice from bio-optical observations in the Baltic Sea

Bio-optics is a powerful approach for estimating photosynthesis rates, but has seldom been applied to sea ice, where measuring photosynthesis is a challenge. We measured absorption coefficients of chromophoric dissolved organic matter (CDOM), algae, and non-algal particles along with solar radiation, albedo and transmittance at four sea-ice stations in the Gulf of Finland, Baltic Sea. This unique compilation of optical and biological data for Baltic Sea ice was used to build a radiative transfer model describing the light field and the light absorption by algae in 1-cm increments. The maximum quantum yields and photoadaptation of photosynthesis were determined from 14C-incorporation in photosynthetic-irradiance experiments using melted ice. The quantum yields were applied to the radiative transfer model estimating the rate of photosynthesis based on incident solar irradiance measured at 1-min intervals. The calculated depth-integrated mean primary production was 5 mg C m–2 d–1 for the surface layer (0–20 cm ice depth) at Station 3 (fast ice) and 0.5 mg C m–2 d–1 for the bottom layer (20–57 cm ice depth). Additional calculations were performed for typical sea ice in the area in March using all ice types and a typical light spectrum, resulting in depth-integrated mean primary production rates of 34 and 5.6 mg C m–2 d–1 in surface ice and bottom ice, respectively. These calculated rates were compared to rates determined from 14C incorporation experiments with melted ice incubated in situ. The rate of the calculated photosynthesis and the rates measured in situ at Station 3 were lower than those calculated by the bio-optical algorithm for typical conditions in March in the Gulf of Finland by the bio-optical algorithm. Nevertheless, our study shows the applicability of bio-optics for estimating the photosynthesis of sea-ice algae.

opencc-zeroDec 2018View details →

Data from: Effects of distance on detectability of Arctic waterfowl using double-observer sampling during helicopter surveys

Aerial survey is an important, widely employed approach for estimating free‐ranging wildlife over large or inaccessible study areas. We studied how a distance covariate influenced probability of double‐observer detections for birds counted during a helicopter survey in Canada's central Arctic. Two observers, one behind the other but visually obscured from each other, counted birds in an incompletely shared field of view to a distance of 200 m. Each observer assigned detections to one of five 40‐m distance bins, guided by semi‐transparent marks on aircraft windows. Detections were recorded with distance bin, taxonomic group, wing‐flapping behavior, and group size. We compared two general model‐based estimation approaches pertinent to sampling wildlife under such situations. One was based on double‐observer methods without distance information, that provide sampling analogous to that required for mark–recapture (MR) estimation of detection probability, urn:x-wiley:20457758:media:ece34824:ece34824-math-0001, and group abundance, urn:x-wiley:20457758:media:ece34824:ece34824-math-0002, along a fixed‐width strip transect. The other method incorporated double‐observer MR with a categorical distance covariate (MRD). A priori, we were concerned that estimators from MR models were compromised by heterogeneity in urn:x-wiley:20457758:media:ece34824:ece34824-math-0003 due to un‐modeled distance information; that is, more distant birds are less likely to be detected by both observers, with the predicted effect that urn:x-wiley:20457758:media:ece34824:ece34824-math-0004 would be biased high, and urn:x-wiley:20457758:media:ece34824:ece34824-math-0005 biased low. We found that, despite increased complexity, MRD models (ΔAICc range: 0–16) fit data far better than MR models (ΔAICc range: 204–258). However, contrary to expectation, the more naïve MR estimators of urn:x-wiley:20457758:media:ece34824:ece34824-math-0006 were biased low in all cases, but only by 2%–5% in most cases. We suspect that this apparently anomalous finding was the result of specific limitations to, and trade‐offs in, visibility by observers on the survey platform used. While MR models provided acceptable point estimates of group abundance, their far higher stranded errors (0%–40%) compared to MRD estimates would compromise ability to detect temporal or spatial differences in abundance. Given improved precision of MRD models relative to MR models, and the possibility of bias when using MR methods from other survey platforms, we recommend avian ecologists use MRD protocols and estimation procedures when surveying Arctic bird populations.