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The global seagrass decline has prompted numerous restoration efforts to reverse current trends. Yet, restoration efforts are challenged by ecological feedbacks and prevalent stressors. Identifying these stressors and the thresholds where seagrass shoot production becomes negative is vital to improve site-selection procedures and increase restoration success. In this study, we investigated the ecological compensation irradiance (ECI) and depth limit of eelgrass ( Zostera marina L) transplants along a eutrophication gradient. This was accomplished by establishing eelgrass transplants along eutrophication and depth gradients while continuously measuring benthic Photosynthetically Active Radiation (PAR). High-temporal monitoring of shoot count allowed precise estimates of shoot production, which was applied to modified photosynthesis-irradiance curves, thereby estimating the ECI. The ECI fell within the interval 2.6 – 9.8 E m -2 d -1 and responded distinctly along the eutrophication gradient, decreasing as eutrophication and nutrient-derived stressors were alleviated. The depth limits were concurrently controlled by irradiance and ECI and similarly responded along the eutrophication gradient, increasing from 1.1 m at the innermost station to 4.7 – 5.6 m at the two outermost least eutrophic stations. The results demonstrate that the ECI of eelgrass varies according to the local environment, with implications for habitat suitability assessment and site selection procedures in restoration efforts.

Light-related visual disturbances are common symptoms among patients with dry eye disease (DED) but difficult to be evaluated in the clinical practice. This cross-sectional, multicenter, controlled study aimed at comparing light discomfort thresholds in healthy individuals and patients with DED, and to further correlate thresholds with ocular surface parameters. The Lumiz 100 device (Essilor International, Paris, France) was employed to measure light discomfort thresholds in 25 patients with DED and 25 sex- and age-matched healthy subjects under different lighting conditions: continuous warm, continuous cold and flashing warm. Participants were instructed to press a button twice to signal discomfort levels as “just perceptible” and “really disturbing”. The mean of the two values was calculated for each lighting condition. DED patients exhibited lower discomfort thresholds for all measurements compared to controls (continuous warm: 2.81 ± 0.56 log10[lux] vs. 3.47 ± 0.51 log10[lux], continuous cold: 2.78 ± 0.54 log10[lux] vs. 3.48 ± 0.50 log10[lux], flashing warm: 2.54 ± 0.53 log10[lux] vs. 3.12 ± 0.69 log10[lux], all p  ≤ 0.004). A significant negative correlation was found between total light sensitivity threshold and ocular discomfort symptoms in patients with DED ( r =-0.499, p  = 0.011). Conversely, no significant correlation was found between light thresholds and the other ocular surface parameters. These findings show that DED patients have a higher light sensitivity than healthy subjects.

The perspective on water transparency changed since the early days of limnology from being a physical parameter of optical water property to an ecological indicator tracking algal turbidity due to eutrophication or an overall success of sustained lake restoration in the late 60ies to 80ies. In modern cities, where ecosystems are commonly deteriorated by man-made modifications, water transparency offers a great opportunity to the public to raise socio-ecological consciousness concerning urban green-blue spaces. We thus re-emphasise water transparency as a key indicator of multi-functional value when assessing an oxbow lake of the riverine floodplain in Vienna, the Alte Donau. Our study covers the eutrophication from 1987-1994 due to the inclusion of the riverine landscape in the urban area, the following lake restoration with an ecosystem shift from a nutrient-rich, algal-turbid water body to a nutrient-poor, clear-water macrophyte controlled system and the impact of global warming in recent decades. We used light attenuation profiles to identify depth layers of specific ambient light requirements for photosynthetic domains (phytoplankton and submerged macrophytes), and to interpret Secchi measurements. Here we calculated the depth at 1% (minimum light requirements for phytoplankton growth as euphotic depth), 3% (minimum light requirements for macrophytes as maximum macrophyte colonization depth) and 12% (preferred light requirements for phytoplankton development) of surface ambient light. A Secchi disk water transparency of 1.5m (“lake bottom view”), judged as good water quality by human perception, refers to mesotrophic conditions with a maximum colonization depth for macrophytes exceeding the mean lake depth in Alte Donau. Water clarity required for sustained macrophyte growth, in particular for favouring bottom-dwelling Chara meadows instead of tall-growing Myriophyllum spicatum, is 3.5m Secchi depth and thus exceeds by far water clarity requested due to bathing aesthetics. Global warming, mirrored by an advanced warming in spring seems to favor significantly a higher yield of macrophytes mainly built up by Myriophyllum at the expense of the yield of algae. The prolongation of the summer period above 21°C, however, coincides with lowered Secchi transparency. Water visibility during the hot season thus seems to be slightly hampered against lake restoration efforts by global warming.

Stingless bees constitute a species-rich tribe of tropical and subtropical eusocial Apidae that act as important pollinators for flowering plants. Many foraging tasks rely on vision, e.g. spatial orientation and detection of food sources and nest entrances. Meliponini workers are usually small, which sets limits on eye morphology and thus quality of vision. Limitations are expected both on acuity, and thus on the ability to detect objects from a distance, as well as on sensitivity, and thus on the foraging time window at dusk and dawn. In this study, we determined light intensity thresholds for flight under dim light conditions in eight stingless bee species in relation to body size in a Neotropical lowland rainforest. Species varied in body size (0.8–1.7 mm thorax-width), and we found a strong negative correlation with light intensity thresholds (0.1–79 lx). Further, we measured eye size, ocelli diameter, ommatidia number, and facet diameter. All parameters significantly correlated with body size. A disproportionately low light intensity threshold in the minute Trigonisca pipioli , together with a large eye parameter P eye suggests specific adaptations to circumvent the optical constraints imposed by the small body size. We discuss the implications of body size in bees on foraging behavior.

To quantitatively assess light sensitivity thresholds and ocular surface parameters in patients with thyroid eye disease (TED) compared to sex- and age-matched patients with dry eye disease (DED) and healthy controls, and to further investigate differences between moderate-to-severe active and mild non-active TED. This cross-sectional, controlled study included patients with TED, patients with DED, and healthy controls. Light sensitivity was evaluated using the Lumiz 100 device (Essilor International, Paris, France) under three lighting conditions: continuous warm, continuous cold and flashing warm. TED patients were further stratified into moderate-to-severe active and mild non-active subgroups. In addition, ocular surface parameters were assessed using the Keratograph 5M (Oculus, Wetzlar, Germany). Correlations between light sensitivity thresholds and clinical parameters were analyzed. Out of 93 included patients, 39 had TED (14 moderate-to-severe active, 25 mild non-active), 25 had DED, and 29 were healthy controls. TED patients demonstrated significantly lower total light sensitivity thresholds compared to healthy controls (3.17 ± 0.52 vs 3.47 ± 0.42 log10[lux], p = 0.040) but higher thresholds compared to DED patients (2.71 ± 0.52 log10[lux], p = 0.003). Among TED patients, those with moderate-to-severe active disease exhibited significantly lower light sensitivity thresholds than those with mild non-active disease (2.85 ± 0.48 vs 3.35 ± 0.47 log10[lux], p = 0.004). A significant negative correlation was found between total light sensitivity threshold and ocular discomfort symptoms in both subgroups of TED patients (r =-0.623, p = 0.017 for moderate-to-severe active TED and r = -0.405, p = 0.045 for mild non-active TED, respectively). Conversely, no significant correlation was found between light thresholds and tear film or thyroid function parameters. Light sensitivity represents a significant and quantifiable manifestation of TED, particularly in patients with active disease. Quantitative assessment of light sensitivity might be incorporated into clinical evaluation of TED patients to better characterize disease burden and guide management strategies.

Aims: To evaluate, with fundus perimetry, the peripapillary differential light threshold (DLT) in eyes with glaucoma and ocular hypertension (OHT), and compare it with peripapillary retinal nerve fibre layer (RNFL) thickness. Methods: 35 glaucomatous, 29 OHT and 24 control eyes were included. Peripapillary DLT at 1° from the optic nerve head was quantified with fundus perimetry; peripapillary RNFL thickness was measured over the same area by optical coherence tomography. Results: Mean (SD) peripapillary DLT was 19.2 (1.7), 17.6 (4.2) and 10.1 (6.9) dB in control, OHT and glaucomatous eyes, respectively (p<0.001). Mean (SD) RNFL thickness was 98.4 (35.3), 83.9 (35.1) and 55.8 (28.2) μm, respectively (p<0.001). Mean peripapillary DLT showed higher sensitivity and specificity in differentiating the three groups compared with RNFL thickness. Conclusion: Progressive, significant reduction of peripapillary DLT was documented in OHT and glaucomatous eyes compared with controls (p<0.001). DLT reduction parallels RNFL reduction.

Light intensity thresholds for school formation were examined in 3 stages (20, 65, and 120 mm) of striped jack Pseudocaranx dentex juveniles with behavioural and histological approaches. Behaviour under a light intensity of 300 to 10–5 lx was recorded using a video camera, and schooling behaviour, swimming speed, and nearest neighbour distance were analyzed. The retina of fish adapted to each light intensity was histologically examined. The light intensity threshold for schooling behaviour in 20 and 65 mm fish was 5 × 10–2 lx, while that of 120 mm fish was 5 × 10–4 lx. The adaptation ratio, defined as the percentage of cone cell movement, ranged from 30 to 80%, corresponding with 10–3 to 1 lx of light intensity in 120 mm fish, while 20 mm fish showed a much narrower range of adaptation ratio, i.e. from 50 to 70%. Visual acuity increased exponentially with fish total length from 20 to 120 mm, corresponding with the increase of eye diameter. The higher range of adaptation ratio in 120 mm fish should enable them to recognize other fish even under low light intensity conditions and make their light intensity threshold for schooling lower than that of smaller fish. Establishment of behavioural and histological adaptability to lower light intensity should have relevance to the habitat shift that occurs in this juvenile stage from bright shallow reef pelagic waters to the offshore dark deeper area.