Lunar Cycle Research Articles

Acoustic monitoring reveals spatiotemporal occurrence of Nathusius’ pipistrelle at the southern North Sea during autumn migration

Seasonal movements between the summer and winter areas are a widespread phenomenon in bats So far, most information on the migration ecology of bats has been obtained by studies in terrestrial habitats, whereas scientific knowledge on migration over sea is scarce. We performed continuous ultrasonic acoustic monitoring at 13 locations in the southern North Sea during four consecutive years (2017–2020) and analysed the spatiotemporal occurrence of Nathusius’ pipistrelle Pipistrellus nathusii during autumn migration in relation to weather parameters and lunar phase. Our analysis showed that the main autumn migration of Nathusius’ pipistrelle at the southern North Sea occurs from mid-August until late October and most bats within the study area occur off the Noord Holland coast. North Sea crossings frequently last longer than one night; the day is spent roosting at an offshore structure. The strongest migration occurs during nights with tailwinds from the east-northeast, but bats are also recorded offshore with low to moderate headwinds or crosswinds. Bat presence decreased between the full moon and the last quarter and increased just before the new moon. Finally, our observations show that the occurrence of bats at sea was reduced in 2020 in comparison to the previous years. The results of this study show clear spatiotemporal patterns of migratory bat occurrence at the southern North Sea. The spatial distribution can be used in spatial planning of future offshore wind farms, whereas the temporal occurrence and environmental factors that shape offshore migration can be used to develop mitigation measures to reduce the number of bat fatalities.

Spatial and temporal dynamics of a Nassau grouper fish spawning aggregation located on an isolated seamount in Puerto Rico

Abstract The Nassau grouper, Epinephelus striatus, is a slow‐growing, late‐maturing, long‐lived reef fish widely distributed throughout the south‐western North Atlantic. Known for forming large spawning aggregations, numbering tens of thousands, they are now listed as Critically Endangered by the International Union for Conservation of Nature (IUCN). Recently, the only Nassau grouper spawning aggregation in Puerto Rico was documented at Bajo de Sico, a seamount and seasonally closed marine protected area. Studies elsewhere on the spatio‐temporal dynamics of Nassau grouper aggregations have documented how, and how far, fish move from home sites to the spawning site, and have shown the tight link between aggregation formation and the lunar cycle. However, these studies have not evaluated the potential impacts of the reduced spatial extent represented by a seamount, nor have they addressed the impacts of local seasonal protection relative to the size of the closed area and the timing of aggregation formation. Acoustic telemetry was used to quantify the spatio‐temporal dynamics of Nassau grouper spawning aggregation formation at Bajo de Sico. Twenty‐six individuals were tagged and tracked over three consecutive spawning seasons. Nassau grouper formed three or four aggregations per season, corresponding to the lunar cycles from January to April. Individuals displayed high visitation rates to the aggregation site: 98% visited at least two peaks per season; 80% visited multiple seasons. The timing of arrival, departure, and residency at the site were significantly different among individuals and lunar months, indicating significant variability in aggregation formation. Nassau grouper occupied a relatively small staging area (2.7 km2) and courtship arena (0.67 km2) compared with aggregations occurring on continental/insular platforms or large atolls; movements off the seamount may occur but were not detected. Results indicate the current seasonal closure inadequately protects the spawning population on Bajo de Sico and should be extended to the end of June.

Threaded Edition 21: Exploring Māori creation narratives with augmented reality-animated sonic experiences in publication design

In this article, we present the creative strategies implemented on the practice-based research project Threaded Edition 21, an international design magazine published in Aotearoa New Zealand. The editorial model draws from a cultural and collaborative framework situated in Tikanga (customary practices of the Indigenous people of New Zealand), Mātauranga Māori (Māori knowledge) and kawa (protocols). In this Special Edition, the structural format was inspired by Māori Maramataka (lunar cycles) and whakapapa (genealogy), and incorporated queues to communicate the multi-layered Māori creation narrative of Te Kore (nothingness), Te Pō (night realms and darkness), Te Whē Ao (coming in to being) and Te Ao Mārama (light realms). These narratives resided primarily in the virtual realm of augmented reality (AR) (as a spiritual encounter), while the printed matter functioned as an enigmatic vessel, creating an ontological reversal where the ‘virtual’ (AR) answered to the ambiguities of ‘real’ (publication). AR-animated vignettes and sonic artistry were activated through printed motifs to incorporate hau (breath of life) into the pages. The AR-animated sonic experience expanded the connection with the audience that when synthesized, provided a sense of immersion into the domain of the unseen which is felt aurally and visually. Structurally, the AR pages open with a chanted karakia (a welcoming prayer) and end with a mihi (closing speech), creating a balance that acknowledges aspects of Māori cultural significance and dualities. When scanned, the AR-animated sonic experiences direct the audience to the accessibility of the Instagram platform, expanding the materiality of printed matter. This approach afforded distinct modes of cognitive processing that combined the visual and the linguistic, the spatial and the temporal, sound and virtual reality to graphically symbolize the many layers and dimensions of things unseen: the realm between being and non-being.

A Preliminary Studies of Fish Richness in the Tondano River Estuary Manado Bay

The purpose of this study was to analyze the richness of fish species in the Tondano River estuary. Sampling was done for two months, in July and August 2022, new moon phase, during the low tide at 13.00-16.00 pm. Sampling used a 20-m beach seine with a cod-end part of 0.2-cm mesh and wings of 2-m height and 1.5-cm mesh. The beach seine was operated 10 times starting from the lowest tide at 13.00 pm to the tide condition at 16.00 pm. As a whole, 736 individuals were caught, consisting of 24 species and 17 families, 14 migrant species, and 10 resident species The number of fish varied from 1 to 445 individuals, in which Terapon jarbua (445 ind) was the most abundant, followed by Neovespicula depressifrons (70 ind). The dominant index (C) was 0.38 and the diversity index (H) was 1.65. The resident species were 120 individuals varying from 2 to 70 ind., and the most abundant was Neovespicula depressifrons (70 ind.). The dominant index (C) was 0.37 and the diversity index was 1.47.

Seasonal and diel variations in the acoustic communication of tree hyraxes in Taita Hills, Kenya

Tree hyraxes (Dendrohyrax spp.) are highly vocal, elusive nocturnal mammals that live in forests across much of Sub-Saharan Africa. Here, we studied how tree hyrax acoustic communication activity varies during the year in a moist montane forest in Taita Hills, Kenya. Our study increases the knowledge about the seasonal and diel variation in tree hyrax calling activity and on the impact of exogenous factors on the calling behavior of the species. A group of tree hyraxes called 700–2000 times during the night, and calling rate was highest during dry season months. Calling activity was bimodal, with peaks between 19.00 and 20.00 h in the evening and between 04.00 and 05.00 h in the morning; however, counter-calling bouts occurred throughout the night. Singing peaked in May, possibly coinciding with the species’ mating season. Calling activity decreased during full moon phases, probably because the animals felt vulnerable to predation. Tree hyrax calling was suppressed by rain, as rainfall is a powerful acoustic competitor. Annual changes in night temperature, the background chorus of vocalizing orthopterans, or the competing calls of nocturnal primates did not reduce tree hyrax calling rates. The latter suggests that sympatric nocturnal mammals have adapted to each other’s calls as an intrinsic feature of the soundscape of their forest habitat.

Measurement and Uncertainty Analysis of Lunar Soil Water Content via Heating Flux Method

According to the big impact hypothesis, the moon should be very dry. However, more and more evidence from the remote sensing of the moon in recent years indicates that there is a lot of water in the moon’s polar regions. Researching the source and distribution of volatiles such as water can provide a key constraint on the formation and evolution of the moon. If there is a large amount of a volatile such as water ice in the polar area of the moon, it can be used as a further resource. Regrettably, there are no detectors in place to detect the amount and presence of water to date. In the new wave of lunar exploration, polar water has become one of the main tasks of NASA, ESA and RKA. The Chang’e-7 spacecraft of China’s fourth lunar exploration phase has also used the Water Molecular Analyzer and the Lunar Soil Volatile Measuring Instrument to detect water content in the lunar polar region. This paper introduces a set of methods and principles for analyzing water content via the heat flux method according to the characteristics of the Lunar Soil Volatile Measuring Instrument that was deployed on the lunar surface. According to the current design, the water content of 0.008~0.17% can be analyzed.

Movement behavior of swordfish provisions connectivity between the temperate and tropical southwest Pacific Ocean

Swordfish (Xiphias gladius) are a widely distributed (45°N–45°S) large pelagic fish targeted by fisheries worldwide. Swordfish that occur at high latitudes tend to disproportionately be large adults, so their movements have implications for population dynamics and fisheries management. In the southwest Pacific, little is known about this subset of the stock and existing evidence suggests limited movement from the subtropics into cooler high latitude waters. Here, we capitalize on the recent emergence of a recreational swordfish fishery off temperate southeast Australia to characterize movements of swordfish caught in the fishery with pop-up satellite archival transmitting tags. Data were recovered from tags deployed for 56–250 days on 11 swordfish (50–350 kg) tagged between 38 and 43°S in the western Tasman Sea. Five swordfish entered the Coral Sea (< 30°S), with four reaching north to 11–24°S, up to 3275 km away from location of capture. Behavior modelling suggests these four individuals rapidly transited north until encountering 23–27 °C water, at which point they lingered in the area for several months, consistent with spawning-related partial migration. One migrating swordfish still carrying a tag after the spawning season returned to ~ 120 km of its release location, suggesting site fidelity. Movements toward the central south Pacific were confined to two individuals crossing 165°E. Swordfish predominantly underwent normal diel vertical migration, descending into the mesopelagic zone at dawn (median daytime depth 494.9 m, 95% CI 460.4–529.5 m). Light attenuation predicted daytime depth, with swordfish rising by up to 195 m in turbid water. At night, swordfish were deeper during the full moon, median night-time depth 45.8 m (37.8–55.5) m versus 18.0 m (14.9–21.8) m at new moon. Modelling fine-scale (10 min−1) swordfish depth revealed dynamic effects of moon phase varying predictably across time of night with implications for fisheries interactions. Studying highly migratory fishes near distribution limits allows characterization of the full range of movement phenotypes within a population, a key consideration for important fish stocks in changing oceans.

Does exposure to moonlight affect day/night changes in melatonin and metabolic parameters in Amazonian fish?

Lunar cycle modulates the rhythmic activity patterns of many animals, including fish. The effect of the moonlight cycle on daily melatonin and metabolic parameters was evaluated in matrinxã (Brycon amazonicus) subjected to external natural lighting. Eighty juvenile were distributed in 4 tanks of 1m3 (20 fish/tank) and divided into two groups. One group was exposed to the full moon and the other group to the new moon for 30 days, which corresponds to the duration of the lunar period. At the end of the lunar phase, 6 fish from each group were anesthetized to collect blood, tissue and eye samples at midday and midnight. The comparison between the light and dark periods revealed a significant increase in plasma and ocular melatonin in the last period. However, there was no significant difference for plasma melatonin between moons. Ocular melatonin presented higher concentrations during the new moon. Glucose, total proteins, cortisol, liver glutathione and gill lipid peroxidation were higher in the full moon compared to in the new moon. Plasma triglyceride was higher during the night for the full moon, and the opposite was found for the new moon. Total cholesterol values were higher at night regardless the moon phase. Glutathione in the gills and lipid peroxidation in the liver showed no significant differences. These results highlight the importance of considering both the day and lunar cycles for melatonin and metabolic parameters in species of commercial interest and susceptible to stressful situations in rearing conditions.

Studi distribusi tertangkapnya ikan pada Soma Tono selama satu siklus bulan

This study aims to determine the distribution of caught fish in "soma tono" and the types of fish caught and how the fish are caught. Soma Tono is classified in gillnets that are rectangular in shape and equipped with buoys, upper ropes, lower ropes, weights and sign buoys. Operation of soma tono fishing gear consists of preparation, net lowering (setting), soaking (soaking) and lifting the net (hauling). The principle of soma tono fishing gear (gillnet) is to wait for fish to be entangled in the body of the net. The method used is a descriptive method, namely managing data obtained when making observations, interviews and documentation. The dominance of fish obtained by bounced fish, the type of fish obtained is the dominance of demersal fish or bottom fish, namely jackfruit seed fish (Upeneus molluccensin), lencam fish (Letrinus lencan), snapper fish (Lutjanus campechanus), lolosi fish (Caesio chrysozona), kuwe fish (Caranx ignobilis), grouper (Epinephelus longispinis), curisi fish (Nemipterus nemaptohorus), sako fish (Tylosurus crocodilus), parrotfish (Scarus rivulatus Valenciennes), puffer fish (Tetraodontidae), sardines (Amblygaster sirm), baronang fish (Siganus) and sea eels (Muraenidae). The results obtained four phases of the moon, namely the 1st quarter moon phase (101.5 kg), the new moon phase (168.7 kg), 2nd quarter moon phase (89 kg) and the full moon phase (63kg).

Disk-integrated and disk-resolved photometry of the Moon with GaoFen-4 space observations

The GaoFen-4 (GF-4) satellite obtained high-resolution images of the entire lunar disk in a single exposure without atmospheric disturbance. These data are favorable for the study of both disk-resolved and disk-integrated photometric properties of the Moon. Using the GF-4 observations, we modeled the lunar reflectance phase functions with the Hapke model and analyzed the lunar photometric properties. The results indicate that the lunar surface exhibits pronounced backscattering, and the maria appear to be smoother compared to the highlands. The disk-resolved and disk-integrated models produced different best-fit parameters for the whole Moon, with the disk-integrated model fitting the small phase angle data better, and the disk-resolved model showing a more favorable appearance at large phase angles. By calculating the disk-integrated phase function with a disk-resolved method, the study confirms the equivalence of the two models, albeit with a small discrepancy due to an imperfect approximation of the roughness function. This discrepancy is due to the different forms of the phase function used in the models. The geometric albedo of the Moon derived from the disk-resolved model is 0.137 and the spherical albedo is 0.063 for Band 3 of GF-4 at 560.6 nm. This study observed an arched phase curve of the ratio of reflectance in two wavelengths, indicating a phenomenon of phase reddening at small phase angles and bluing at large phase angles.

Regional peculiarities of the Zrubna/Timber-grave culture tribes’ calendar system

The article presents the results of the study on the burial of the Zrubna/Timber-Grave culture (Late Bronze Age) from the mound near the village of Komyshuvate in the North Azov Area in the south of Donetsk Region of Ukraine. The article deals with issues related to some peculiarities of the material and spiritual culture of the ancient population of the Azov steppes, their social organization and funeral rites. Ceramic vessels are the most common category of equipment in the funerary inventory of the Zrubna/Timber-grave culture graves. Finds of pottery with extraordinary ornaments, which researchers interpret as pictograms, proto-literacy, and plot drawings, have always been of particular interest. The calendar ornamentation on the pots of the Zrubna/Timber-grave culture deserves special attention. The pot with the ornamentation, which, according to the authors, was of a calendar nature, comes from burial 1 of barrow 4 of the Komyshuvate cemetery. A detailed analysis of the ornamentation on the pot from this burial allowed us to suggest that the cyclic composition depicted on the ceramic vessel records recurring time periods that were important to the ancient population. Perhaps the ornament also reflects the regional peculiarities of the calendar system of the Zrubna/Timber-grave culture tribes: annual and lunar cycles with the time of transition from the old to the new year.

On the Zhou Bronze Annals Calculated by the Dates and the Moon Phases in Bronze Inscriptions

On the Zhou Bronze Annals Calculated by the Dates and the Moon Phases in Bronze Inscriptions

FOOD PREFERENCES OF EARLY JUVENILE SCALLOPED SPINY LOBSTER IN EKAS BAY, LOMBOK, INDONESIA

Ekas Bay is the largest bay on the island of Lombok which is the location for catching and cultivating spiny lobsters. This research was conducted from May to July 2021 on the Scalloped spiny lobster (Panulirus homarus). This study aims to identify the types of natural foods consumed and determine the preferred types of food, as well as the early juvenile feeding time of Scalloped spiny lobster located in Ekas Bay, East Lombok Regency, West Nusa Tenggara Province (NTB). Puerulus samples were collected in the last week of May 2021, enlarged puerulus was performed in submerged cages measuring 15 cm × 15 cm × 15 cm, mesh size &lt;3 mm, with a density of 4 puerulus/m2. The cages are placed at a location 70 m to the sea from the shoreline, at a depth of 0.5, 1.0, and 1.5 m. After reaching the juvenile phase, lobsters are collected during the new and full moon phases (06.00 am, 06.00 pm and 12.00 am, respectively) in June to July 2021. A total of 60 individual juvenile lobsters (algal phase) were analyzed for their stomach contents. The average percentage of the total Index of Relative Important (IRI) obtained for the identified taxa were bivalves (22.32%), copepods (23.64%), demosponges (24.98%), while digestibdle material was 29.06%. The electivity index data (Ei) shows that lobsters prefer bivalves over other taxa. Lobster samples taken in the morning had a stomach fullness rate of 50%, indicating active feeding at night.

Intense scuba diving does not alter activity patterns of predatory reef fish: Evidence from a protected tourism hotspot

The rise of nature-based tourism has provided a new avenue for disturbing animal behaviour, especially in protected areas. One of the most important tourism sectors in aquatic environments is scuba diving, an activity considered sustainable given its non-extractive nature and capability of bringing relevant socio-economic benefits to local communities. However, knowledge about its impact on the activity patterns of aquatic animals is still scarce. Here, we used biotelemetry techniques to assess the importance of scuba diving in modulating the activity patterns of the dusky grouper (Epinephelus marginatus, Lowe, 1834), a marine predatory fish of high interest for fishing and tourism. We implemented Hidden Markov Models (HMMs) on high-resolution acceleration data using a temporal and spatial control while controlling for a set of environmental variables (i.e. photoperiod, time-of-day, moon phase, temperature, wave height, and intensity and direction of marine currents) within a multiple-use marine protected area, and diving tourism hot-spot, of the western Mediterranean Sea. Our results underlined the more decisive influence of environmental-related stressors on the activity patterns of the dusky grouper compared to the impact of scuba diving. A high heterogeneity existed in the response against most of the stressors, including the presence of scuba divers. Overall, the activity of dusky grouper was higher at night than at day, showing a positive relationship with wave height, water temperature, and current intensity and a negative one with the moon phase. Remarkably, our findings, based on novel biotelemetry tools, differed substantially from the common wisdom accepted for this species. In conclusion, there is no clear evidence of scuba divers influence on the general activity patterns of the dusky grouper. Beyond their relevance from an ecological perspective, these results provide useful insights for the sustainable management of coastal resources, suggesting that scuba diving, when properly carried out, can represent an important sector to foster for the blue growth of coastal communities.

Sustainability of tunas and swordfish exploitation in the equatorial tropical Atlantic Ocean

Fishing is important as it generates employment, income, high-quality food and livelihoods for native communities in many parts of the world. However, when poorly managed, it can cause irreversible overfishing impacts on the ecology of communities. The present study aimed to construct models to estimate the presence probability of young specimens of Thunnus albacares, Thunnus obesus and Xiphias gladius in the Western Equatorial Tropical Atlantic Ocean (WETA) using oceanographic, temporal, and spatial variables. The data used were generated by monitoring the fishing operations of vessels of the pelagic longline fleet in the extreme northeast of Brazil. The Generalized Additive Model was used to estimate the effect of different factors and covariates (oceanographic, temporal, and spatial variables) on the juvenile probability of the presence of the species T. albacares, T. obesus and X. gladius. The capture of juveniles becomes graver in the results obtained annually, for T. albacares ranged between 12.4% and 50.5%, T. obesus ranging from 27.5% to 36.4% and X. gladius from 0% to 13.8% immatures. Models established indicated that water temperature, year, longitude, chlorophyll-a and the interactions between moon phases and latitude, as well as the interactions between quarters and latitude, are statistically significant, influencing the distribution of juveniles of these resources. More efforts and attention should be directed to investigating the distribution of juvenile presence in the WETA, mainly in the southern hemisphere. We want to initiate here a broad discussion and campaign for establishing studies aiming at the constant monitoring of juvenile levels captured.

Genetic analysis of a phenotypic loss in the mechanosensory entrainment of a circalunar clock.

Genetic variants underlying traits that become either non-adaptive or selectively neutral are expected to have altered evolutionary trajectories. Uncovering genetic signatures associated with phenotypic loss presents the opportunity to discover the molecular basis for the phenotype in populations where it persists. Here we study circalunar clocks in populations of the marine midge Clunio marinus. The circalunar clock synchronizes development to the lunar phase, and it is set by moonlight and tidal cycles of mechanical agitation. Two out of ten studied populations have lost their sensitivity to mechanical agitation while preserving sensitivity to moonlight. Intriguingly, the F1 offspring of the two insensitive populations regained the sensitivity to mechanical entrainment, implying a genetically independent loss of the phenotype. By combining quantitative trait locus mapping and genome-wide screens, we explored the genetics of this phenotypic loss. QTL analysis suggested an oligogenic origin with one prevalent additive locus in one of the strains. In addition, it confirmed a distinct genetic architecture in the two insensitive populations. Genomic screens further uncovered several candidate genes underlying QTL regions. The strongest signal under the most prominent QTL contains a duplicated STAT1 gene, which has a well-established role in development, and CG022363, an ortholog of the Drosophila melanogaster CG32100 gene, which plays a role in gravitaxis. Our results support the notion that adaptive phenotypes have a complex genetic basis with mutations occurring at several loci. By dissecting the most prevalent signals, we started to reveal the molecular machinery responsible for the entrainment of the circalunar clock.

Evidence of ontogenetic partitioning of restored coastal habitat by a generalist sportfish

Coastal and estuarine habitats that provide crucial nursery areas for many economically and ecologically important fish species are in decline. Restoration of benthic habitats can improve fish populations, biomass, and feeding opportunities, but there is limited research on how restoration impacts growth and survival with ontogeny. To address this knowledge gap, here we examine the biometrics (size, biomass, and body condition), recruitment, size structure, and trophic shifts of a sportfish (mangrove snapper, Lutjanus griseus) at restored oyster reefs and stabilized living shorelines to better understand how fish use restored habitats as they grow. Biomass and body condition of L. griseus juveniles and subadults, and post‐settlement recruitment, at restored/stabilized sites was similar, and in some cases greater than natural sites, correlating with benthic habitat, reef location, and lunar phase at oyster reefs. Living shorelines exhibited greater recruitment potential, while oyster reefs supported more juveniles and subadults, as evidenced by differences in fish size and biomass between habitats. Dietary overlap implies subadult L. griseus likely foraged across habitats more than juveniles, while there was greater diet similarity within habitats. Furthermore, ontogenetic shifts also occurred within oyster reef habitats, highlighting the importance of quality habitat to support various sportfish life stages, which can be achieved through restoration. These findings suggest life history attributes can be indicators of habitat restoration success, and specifically provide actionable science to guide the development of more effective strategies for restoring inshore nursery habitats and thus augment production of offshore reef fisheries.

Moonlight surgery: no influence of moon phase or Friday 13th on outcomes of total knee arthroplasty.

The purpose of the present study was to investigate associations between revision-free survival and functional scores of total knee arthroplasty (TKA) and moon phase on the day of surgery, as well as operations performed on a Friday 13th. The data of all patients that received TKA between 2003 and 2019 were extracted from the Tyrol arthroplasty registry. Patients that had undergone previous total or partial knee arthroplasty as well as patients that had missing pre- or post-operative WOMAC were excluded. Patients were allocated to one of the following four groups according to moon phase on the day of surgery: new, waxing, full and waning. Patients operated on a Friday 13th were also identified and compared to patients operated on any other days/dates. A total of 5923 patients met the inclusion criteria, with mean age of 69 ± 9years, and comprising 62% women. There were no significant differences in revision-free survival among the four moon phase groups (p = 0.479), and no significant differences in preoperative and postoperative total WOMAC (p = 0.260, p = 0.122), There were no significant differences in revision-free survival patients operated on Friday 13th vs. other days/dates (p = 0.440). The preoperative total WOMAC was significantly worse for patients operated on a Friday 13th (p = 0.013), which was observed in the pain (p = 0.032) and function (p = 0.010) subscales. There were no significant differences in postoperative total WOMAC at 1year follow-up (p = 0.122). Neither moon phase on the day of surgery nor Friday 13th were associated with revision-free survival or clinical scores of TKA. Patients operated on a Friday 13th had significantly worse preoperative total WOMAC but similar postoperative total WOMAC at 1-year follow-up. These findings could help reassure patients that TKA renders consistent outcomes regardless of the preoperative pain or function, and in spite of bad omens or moon phases.

NSKY-CD: A System for Cloud Detection Based on Night Sky Brightness and Sky Temperature

Cloud cover is important meteorological information that still requires expensive equipment to be monitored from the ground, especially at night. The use of artificial lights at night causes light pollution, and clouds amplify this by reflecting light downward. In addition, cloud thermal radiation emissions affect sky temperature. In this study, we describe a system (NSKY-CD) that can be used to detect clouds at night since it integrates a sky quality meter that measures night sky brightness (NSB) and an air temperature and an infrared temperature sensor that measure sky temperature. We defined a cloud detection method based on fixed threshold values determined with two different procedures that we called ‘optimal’ and ‘antimode’. We then quantitatively assessed the performance of these methods in detecting the presence or absence of clouds in the urban area of Florence during two full moon cycles. Accuracy for the ‘optimal’ method varied between 87% and 91%, while for the ‘antimode’ method, it varied between 86% and 89%. Our results suggest that the two parameters are complementary since NSB has a better performance on moonless nights, and the difference between air temperature and sky temperature has a better performance on moonlit nights. Our method can also be used to analyze historical series of NSB to estimate cloud presence backwards, thus providing important information for meteorological, environmental and astronomical studies.

Spawning ecology of the Saint Paul's Gregory Stegastes sanctipauli, a damselfish endemic to the remote St. Peter and St. Paul's Archipelago.

We studied the spawning ecology of Stegastes sanctipauli, a damselfish endemic to the small and remote St. Peter and St. Paul's Archipelago (Brazil), aiming to determine the main correlates of reproductive success, as inferred from rates of egg losses along a spawning season. New clutches appeared mostly in the last quarter moon, when egg predation intensified. Predation by heterospecifics, particularly Halichoeres radiatus (Linnaeus, 1758), accounted for most egg losses, while filial cannibalism showed negligible influence. Predation pressure was highest for larger nests with higher initial density of eggs. Hatching of eggs occurred close to the new moon (i.e. ~5 days after spawning). Most nests occur in shallow reefs (<16 m depth), where main food resources for adults (turf algae) are concentrated, but abundance of egg predators, particularly H. radiatus, is also highest. This later result suggests that the spawning activity of S. sanctipauli is influenced by the trade-offs between food accessibility by adults and egg predation risk. The patterns recorded here are similar to those known for other tropical damselfish species and may reflect strategies for attenuating predation pressure over new fry and eggs.