30 research outputs found
Descending to the twilight-zone: changes in coral reef fish assemblages along a depth gradient down to 65 m
No full textIn contrast to the abundance of literature on the relationship between fish assemblages and habitat structure in the upper 30 in of coral reefs, the deeper (>40 m) parts of coral reefs are rarely studied. We examined changes in reef fish diversity and habitat structure along an increasing depth gradient, including the unknown deep reef. We ran visual and video transects along a substantial depth gradient (0 to 65 in) in the northern Red Sea and extended the known depth distribution for 48 reef species. We found a change in assemblage composition highly correlated to both the depth gradient and a reduction in the abundance of branching corals with depth. The number of reef fish species declined with depth and we also measured a high species turnover as measured by beta diversity (beta(t), beta(w)) in the deep reef. This pattern is mainly due to the replacement of the abundant damselfishes in the shallow reef, which prey on zooplankton, by zooplanktivorous sea basses and wrasses in the deep reef. The steep reduction in branching corals, which most damselfishes use for cover, may be the main factor contributing to this change. We found a peak in species richness (alpha diversity) at 30 m, a peak in beta(w) at 50 to 65 in, and peaks in beta(t) at 30 to 50 in and 50 to 65 m. The 30 in depth stratum shows species of both shallow and deep assemblages generating a transition zone with characters of both deep and shallow habitats. The fish assemblage continues to change with depth, and future research will determine if there exists a depth threshold at which the assemblage will stabilize
Occurrence of BNT162b2 Vaccine Adverse Reactions Is Associated with Enhanced SARS-CoV-2 IgG Antibody Response
No full textPromoting SARS-CoV-2 vaccination has been a global mission since the first vaccines were approved for emergency use. Alongside the excitement following the possibility of eradicating SARS-CoV-2 and ending the COVID-19 pandemic, there has been ample vaccine hesitancy, some due to the abundant reporting of adverse reactions. We report here that the occurrence of BNT162b2 vaccine adverse reactions is associated with enhanced antibody response. We found a statistically significant correlation between having an adverse reaction, whether local or systemic, and higher antibody levels. No sex difference was observed in antibody levels. However, as was recently reported, the antibody response was found to be lower among older vaccinees. The demonstration of a clear correlation between adverse reactions and antibody levels may help reduce vaccination hesitancy by reassuring that the presence of such reactions is an indication of a well-functioning immune system
Care of undocumented-uninsured immigrants in a large urban dialysis unit
No full textAbstract Background: Medical, ethical and financial dilemmas may arise in treating undocumented-uninsured patients with end-stage renal disease (ESRD). Hereby we describe the 10-year experience of treating undocumented-uninsured ESRD patients in a large public dialysis-unit
The Risk of Preterm Birth in Women with Three Consecutive Deliveries—The Effect of Number and Type of Prior Preterm Births
No full textBackground: We aimed to explore the association of the number, order, gestational age and type of prior PTB and the risk of preterm birth (PTB) in the third delivery in women who had three consecutive singleton deliveries. Methods: A retrospective cohort study of all women who had three consecutive singleton births at a single medical center over a 20-year period (1994–2013). The primary outcome was PTB (<37 weeks) in the third delivery. Results: 4472 women met inclusion criteria. The rate of PTB in the third delivery was 4.9%. In the adjusted analysis, the risk of PTB was 3.5% in women with no prior PTBs; 10.9% in women with prior one PTB only in the first pregnancy; 16.2% in women with prior one PTB only in the second pregnancy; and 56.5% in women with prior two PTBs. A similar trend was observed when the outcome of interest was spontaneous PTB and when the exposure was limited to prior spontaneous or indicated PTB. Conclusions: In women with a history of PTB, the risk of recurrent PTB in subsequent pregnancies is related to the number and order of prior PTBs. These factors should be taken into account when stratifying the risk of PTB
Functional changes of the visual system of the damselfish Dascyllus marginatus along its bathymetric range
No full textShallow-water zooplanktivorous fish rely on their vision for foraging In shallow water feeding efficiency decreases in dim light and thus the fish cease foraging at crepuscular hours Creatures living in the lower parts of their depth ranges are expected to be exposed to limited light levels for longer hours However observations of the zooplanktivore Dascyllus marginatus showed little change in foraging duration down to 40 m deep We asked whether the visual system s functionality changes with depth along the depth range of this damselfish we examined eye and retina anatomy for changes in visual acuity and light sensitivity and used the optomotor response to test for spatial and temporal light summation We found only minor changes in the anatomy of the eye that are not expected to affect visual sensitivity or acuity However behavioural experiments showed that the deeper water fish s test performance exceeded those of fish in shallow water under lower light levels We found that deeper water fish responded to the optomotor test at lower light levels and also had more discriminating visual acuity in low light which can Increase their potential reactive distance The plastic adaptive ability of the visual system to low light levels may explain the fish s ability to inhabit deeper reef habitats and thus expand their depth range limits (C) 2010 Elsevier Inc All rights reserve
Polarized light sensitivity and orientation in coral reef fish post-larvae.
No full textRecent studies of the larvae of coral-reef fishes reveal that these tiny vertebrates possess remarkable swimming capabilities, as well as the ability to orient to olfactory, auditory, and visual cues. While navigation according to reef-generated chemicals and sounds can significantly affect dispersal, the effect is limited to the vicinity of the reef. Effective long-distance navigation requires at least one other capacity-the ability to maintain a bearing using, for example, a sun compass. Directional information in the sun's position can take the form of polarized-light related cues (i.e., e-vector orientation and percent polarization) and/or non-polarized-light related cues (i.e., the direct image of the sun, and the brightness and spectral gradients). We examined the response to both types of cues using commercially-reared post-larvae of the spine-cheeked anemonefish Premnas biaculeatus. Initial optomotor trials indicated that the post-larval stages are sensitive to linearly polarized light. Swimming directionality was then tested using a Drifting In-Situ Chamber (DISC), which allowed us to examine the response of the post-larvae to natural variation in light conditions and to manipulated levels of light polarization. Under natural light conditions, 28 of 29 post-larvae showed significant directional swimming (Rayleigh's test p<0.05, R = 0.74±0.23), but to no particular direction. Swimming directionality was positively affected by sky clarity (absence of clouds and haze), which explained 38% of the observed variation. Moreover, post-larvae swimming under fully polarized light exhibited a distinct behavior of tracking the polarization axis, as it rotated along with the DISC. This behavior was not observed under partially-polarized illumination. We view these findings as an indication for the use of sun-related cues, and polarized light signal in specific, by orienting coral-reef fish larvae
Optomotor trials examining sensitivity of <i>Premnas biaculeatus</i> to linearly polarized light.
No full text<p>The proportion of positive optomotor responses (N = 59) to the control, polarized stripes and black-and-white stripes patterns (W, POL and BW; respectively), with different options of considering borderline cases (in which it was hard to decide whether the response was positive or negative). Ratios of fish responding with actual numbers are given in parenthesis. Chi-squared and p-values pertain to a test for the equality of proportions (proportions test); testing the null hypothesis that the probability of responding positively to POL is equal to the expected by chance (W).</p
Mean bearings and directionality of <i>Premnas biaculeatus</i>.
No full text<p>Mean bearings and directionality (R<sub>c</sub>) of 28 <i>P. biaculeatus</i> post-larvae, depicted by the direction and the length of the blue lines respectively. Red polygons represent nearby coral-reef patches.</p
