Abundance Patterns Research Articles

Hot subdwarf wind models with accurate abundances

Context. Helium-dominated subdwarfs are core helium burning stars stripped of their envelope. The nuclear evolution of these stars alters surface abundances. Modified abundances impact the strength of the stellar wind. Aims. We aim to understand the influence of modified surface abundances on the strength of the stellar wind in the helium-dominated subdwarfs CD–46 8926 and CD–51 11879. A modified wind strength could resolve the problem with the X-ray emission of these stars, as the expected X-ray luminosity of both stars is significantly higher than the upper limit determined from observations. Methods. We used our own optical spectroscopy combined with archival ultraviolet spectroscopy and photometry to derive basic parameters and surface abundances of selected subdwarfs. The resulting parameterst served as input for the METUJE stellar wind code, which predicts the wind structure of these stars. We compared the derived wind parameters with the predictions derived for solar abundances. Results. The optical analysis showed that both subdwarfs have effective temperatures in excess of 60 kK and a strong overabundance of carbon in the case of CD–46 8926 and nitrogen in the case of CD–51 11879. We interpret the abundance patterns as being a result of enrichment by the products of nuclear reactions. The modified abundances reduce the wind mass-loss rate by tens of percent. The reduction improves the predicted wind line profiles in comparison to observations. The change in helium abundance does not have a strong effect on the wind parameters. As a result of a lower estimated bolometric luminosity and mass-loss rate and a larger distance, the expected X-ray luminosities become lower and agree with observational upper limits. Conclusions. The nucleosynthesis does not significantly alter the strength of the wind of hot subdwarfs, but the inclusion of proper stellar parameters improves the agreement with observational wind characteristics. Our analysis indicates that subdwarfs overabundant in helium are typically able to launch wind. This conclusion is supported by data gathered for thousands of subdwarfs from the literature, which shows that subdwarfs overabundant in helium avoid the region in the Kiel diagram where the winds are predicted to be absent. This can be interpreted in terms of the gravitational settling of helium, which is suppressed by the winds.

Biennial patterns in Alaskan sockeye salmon ocean growth are associated with pink salmon abundance in the Gulf of Alaska and the Bering Sea

Abstract In response to ocean heating and hatchery production, pink salmon (Oncorhynchus gorbuscha) returning from the North Pacific Ocean steadily increased after 1975, leading to concerns about their influence on food webs and competition with other species. Using measurements of distance between scale annuli of 24 584 individual sockeye salmon (O. nerka), we examined growth during their 2 or 3 years at sea from 1977 to 2015 for eight populations in Alaska. We found significant, negative autocorrelations at 1 lag year in annual growth of sockeye salmon, with a consistent pattern of lower growth in odd years, i.e. opposite to the biennial pattern of pink salmon abundance. Peak pink salmon abundances reduced growth of sockeye salmon from 7 to 14% during the second year in the ocean compared with growth when pink salmon abundance was low, while third-year growth was reduced up to 17%. The overall effect of pink salmon abundance on sockeye growth was over two times greater than the effect of sockeye salmon abundance. Production hatcheries and ocean heating contribute to the competitive dominance of pink salmon, underscoring the need to consider this unintended anthropogenic effect on the growth and productivity of sockeye salmon throughout the North Pacific.

Spectroscopic and photometric behavior of LP Ori

AbstractWe performed spectroscopic and photometric analyses on the early B‐type LP Ori young stellar object located in the Orion Nebula. The high‐resolution spectra of LP Ori was obtained at the Ankara University Kreiken Observatory in 2023, while all spectra recorded over the past 19 years were extracted from the ESO and ESPaDOnS archives. In these spectra of LP Ori, there is typically an emission observed in the core of the Balmer profile. This structure is accompanied by a 14‐year interval inverse P‐Cygni repetition superimposed on the Balmer profile. Additionally, an emission in the 5,875 He I line is visible in the spectra in the year 2023. When this emission is considered together with the inverse P‐Cygni structures, these observations suggest that LP Ori is a Herbig Ae/Be star. The abundance pattern of LP Ori is close to solar with the exception of a slightly rich helium and slightly poor aluminum abundance. Additionally, the spectral energy distribution of LP Ori was constructed to confirm the infrared excess caused by its circumstellar disk. Furthermore, the photometric analysis performed on the TESS observations of LP Ori shows significant photometric variability and the frequency analysis reveals a Cephei star in its forthcoming evolution.

Intestinal microbiota composition and efficacy of iron supplementation in Peruvian children.

Despite repeated public health interventions, anemia prevalence among children remains a concern. We use an evolutionary medicine perspective to examine the intestinal microbiome as a pathway underlying the efficacy of iron-sulfate treatment. This study explores whether gut microbiota composition differs between anemic children who respond and do not respond to treatment at baseline and posttreatment and if specific microbiota taxa remain associated with response to iron supplementation after controlling for relevant inflammatory and pathogenic variables. Data come from 49 pre-school-aged anemic children living in San Juan de Lurigancho, Lima, Peru. We tested for differences in alpha and beta diversity using QIIME 2 and performed differential abundance testing in DESeq2 in R. We ran multivariate regression models to assess associations between abundance of specific taxa and response while controlling for relevant variables in Stata 17. While we found no evidence for gut microbiota diversity associated with child response to iron treatment, we observed several differential abundance patterns between responders and non-responders at both timepoints. Additionally, we present support for a nonzero relationship between lower relative abundance of Barnesiellaceae and response to iron supplementation in samples collected before and after treatment. While larger studies and more specific approaches are needed to understand the relationship between microbes and anemia in an epidemiological context, this study suggests that investigating nutritional status and pathogen exposure is key to better understanding the gut microbiome and impact of iron fortification.

A comparison of two snapshot studies half a century apart suggests stability in a Pacific Northwest winter forest bird community

Populations of many North American bird species have declined throughout the past half century. The majority of studies quantifying these declines have analyzed counts of birds taken during spring and summer, not during the season of scarcity, winter. We re-surveyed seven large study plots in Douglas fir (Pseudotsuga menziesii) forests initially surveyed in winter during the late 1960s in the Oregon Coast Range, USA. We compared density estimates, observed species richness and vegetation structure within plots, and inspected aerial photography to describe changes in landscape-level landcover. To assess potential drivers of change, we reviewed historical climate data and explored patterns of abundance associated with forest age. Observed species richness was greater in the modern surveys. Abundances of four of the six most common bird species appeared to be similar to or slightly lower than 50 years ago as the historical point estimates usually fell within or above 95% confidence intervals generated from our analyses. We found no clear associations with changes in bird communities and forest structure, climate, or forest age. The historical data are unique in providing point estimates of abundance for the entire bird community on each study plot. Yet, some uncertainties in accuracy of the historic counting methods could still influence interpretation of multi-decadal changes in apparent abundance. We conclude that this Pacific Northwest bird community was relatively stable in its abundances of the most common forest-dwelling species and that largely the communities are still intact. Additional production of precisely repeatable surveys of winter bird communities are needed in all habitats to adequately characterize long-term population dynamics during the season of scarcity.

Temperature-dependent dispersal and ectotherm species' distributions in a warming world.

Dispersal is a crucial component of species' responses to climate warming. Warming-induced changes in species' distributions are the outcome of how temperature affects dispersal at the individual level. Yet, there is little or no theory that considers the temperature dependence of dispersal when investigating the impacts of warming on species' distributions. Here I take a first step towards filling this key gap in our knowledge. I focus on ectotherms, species whose body temperature depends on the environmental temperature, not least because they constitute the majority of biodiversity on the planet. I develop a mathematical model of spatial population dynamics that explicitly incorporates mechanistic descriptions of ectotherm life history trait responses to temperature. A novel feature of this framework is the explicit temperature dependence of all phases of dispersal: emigration, transfer and settlement. I report three key findings. First, dispersal, regardless of whether it is random or temperature-dependent, allows both tropical and temperate ectotherms to track warming-induced changes in their thermal environments and to expand their distributions beyond the lower and upper thermal limits of their respective climate envelopes. In the absence of dispersal mortality, warming does not alter these new distributional limits. Second, an analysis based solely on trait response data predicts that tropical ectotherms should be able to expand their distributions polewards to a greater degree than temperate ectotherms. Analysis of the dynamical model confirms this prediction. Tropical ectotherms have an advantage when moving to cooler climates because they experience lower within-patch and dispersal mortality, and their higher thermal optima and maximal birth rates allow them to take advantage of the warmer parts of the year. Previous theory has shown that tropical ectotherms are more successful in invading and adapting the temperate climates than vice versa. This study provides the key missing piece, by showing how temperature-dependent dispersal could facilitate both invasion and adaptation. Third, dispersal mortality does not affect the poleward expansion of ectotherm distributions. But, it prevents both tropical and temperate ectotherms from maintaining sink populations in localities that are too warm to be viable in the absence of dispersal. Dispersal mortality also affects species' abundance patterns, causing a larger decline in abundance throughout the range when species disperse randomly rather than in response to thermal habitat suitability. In this way, dispersal mortality can facilitate the evolution of dispersal modes that maximize fitness in warmer thermal environments.

A case study on the application of spore sampling for the monitoring of macrofungi.

Fungi play a vital role in ecosystem functioning, yet significant knowledge gaps persist in understanding their diversity and distribution leading to uncertainties about their threat status and extinction risk. This is partly owed to the difficulty of monitoring fungi using traditional fruiting body surveys. The present study evaluates airborne environmental DNA (eDNA) sampling as a monitoring tool with a focus on grassland macrofungi. We applied active and passive air sampling methods, complemented by extensive field surveys of waxcap and clavarioid fungi-species groups of high relevance for conservation. Twenty-nine species were recorded during the field surveys, 19 of which were also detectable by ITS2 metabarcoding of the collected samples. An additional 12 species from the studied genera were identified exclusively in air eDNA. We found that the patterns of species detection and read abundance in air samples reflected the abundance and occurrence of fruiting bodies on the field. Dispersal kernels fitted for the three dominant species predicted rapidly decreasing spore concentrations with increasing distance from fruitbodies. Airborne assemblages were dominated by a high diversity of common species, while rare and threatened red-listed species were under-represented, which underscores the difficulty in detecting rare species, not only in conventional surveys. Considering the benefits and drawbacks of air sampling and fruitbody surveys, we conclude that air sampling serves as a cost- and time-efficient tool to characterize local macrofungal communities, providing the potential to facilitate and improve future fungal monitoring efforts.

Vegetation Affects the Responses of Canopy Spider Communities to Elevation Gradients on Changbai Mountain, China.

Forest canopies, an essential part of forest ecosystems, are among the most highly threatened terrestrial habitats. Mountains provide ideal conditions for studying the variation in community structure with elevations. Spiders are one of the most abundant predators of arthropods in terrestrial ecosystems and can have extremely important collective effects on forest ecosystems. How the diversity and composition of canopy spider communities respond to elevation changes in temperate forests remains poorly understood. In this study, we collected canopy spiders from four elevation sites (800 m, 1100 m, 1400 m, and 1700 m) on Changbai Mountain using the fogging method in August 2016. With the methods of ANOVA analysis, transformation-based redundancy analysis, and random forest analysis, we explored the responses of canopy spider communities to elevation. In total, 8826 spiders comprising 81 species were identified and the most abundant families were Thomisidae, Clubionidae, Linyphiidae, and Theridiidae (77.29% of total individuals). Species richness decreased whereas evenness increased with increasing elevation, indicating that elevation has an important impact on community structure. The pattern of absolute abundance was hump shaped with increasing elevation. We found that the community compositions at the three taxonomic levels (species, family, and guild) along the elevation gradient were obviously altered and the variation in community composition was higher at low-elevation sites than at high-elevation sites. There were 19 common species (23.46%) among the four elevations. Regression and RDA results showed that vegetation variables contributed to the variation in the diversity and composition of canopy spiders. Furthermore, the influence of factors would be weakened with the taxonomic level increasing. Therefore, our findings greatly highlight the important role of vegetation in the diversity and composition of canopy spiders and the influence is closely related to the taxonomic level.

Diversity of an Odonata assemblage from a tropical dry forest in San Buenaventura, Jalisco, Mexico (Insecta, Odonata).

The patterns of richness, diversity, and abundance of an odonate assemblage from San Buenaventura, Jalisco are presented here. A total of 1087 specimens from seven families, 35 genera and 66 species were obtained through monthly samplings of five days each during a period of one year. Libellulidae was the most diverse family (28 species), followed by Coenagrionidae (21), Gomphidae (7), Aeshnidae (6), Calopterygidae (2), Lestidae (1) and Platystictidae (1). Argia was the most speciose genus. The highest species richness and Shannon diversity were found during August and September, whereas the highest abundance was observed in June and the highest Simpson diversity was recorded in September - all of which were associated with the rainy season. The highest values of phylogenetic diversity were found from June to October. The different diversity facets of this assemblage were positively correlated with precipitation and minimum temperature, whereas maximum temperature showed no influence. In addition, we found that this odonate diversity was higher than most Mexican localities with tropical dry forest (TDF) studied. We continue our efforts to describe the patterns of richness, diversity and abundance of some insect groups associated with the tropical dry forest ecosystem in Mexico, following a latitudinal gradient of the distribution of this ecosystem in the country. Our emphasis here was to evaluate the spatial and temporal patterns of richness and diversity of an Odonata assemblage from Jalisco, Mexico.

Ecological patterns of intertidal macrofauna across an anthropic gradient on tropical Gulf of Mexico sandy beaches: Insights for assessment

In the context of sandy coastlines under increasing coastal development and squeeze, coupled with the ongoing loss of global diversity, it is crucial to understand the ecological patterns of benthic macrofauna, which plays a key role in the trophic and biogeochemical functional connectivity between land and sea. Here, we assessed differences in the spatiotemporal patterns of macrofauna diversity and production in exposed sandy beaches of the southwestern Gulf of Mexico across a use and modification gradient and its utility as indicators of impacts. We also estimated the sampling effort for a representative species inventory, considering three tidal zones, and longitudinal spatial scales in four beaches twice a year, and locally after an event of great tourist incidence. The traditional diversity indices could not conclusively detect the stress gradient of the macrofauna in these systems. The abundance pattern of macrofauna species in the upper intertidal zone and the greater secondary production at the lower zone of the unmodified beaches could be useful as indicators of ecological integrity in natural beaches with similar morphodynamic conditions. On the contrary, the most disturbed beach exhibited greater instability in terms of its macrofauna temporal variation in the lower zone. We verified that the ecological integrity approach comprising both natural and anthropogenic factors and multiple stressors is a useful tool showing precisely how beach-intensive use and modification induce instability and less resilience of its macrofauna, reflected in the species' distribution by tidal zones, and the secondary production patterns. We also provide the first estimate of the optimal sampling effort required to get a representative inventory of the benthic intertidal macrofauna in sandy beaches of the Western Gulf of Mexico within a gradient.

Influence of light neutron-rich exotic nuclei in deciding abundance patterns relevant for explosive nucleosynthesis

Exotic neutron-rich nuclei play an important role in r-process nucleosynthesis. We study the effect of including proper nuclear structure to calculate neutron capture and photodisintegration rates, especially for 19C and 20N, under the aegis of post-form distorted wave Born approximation (FRDWBA). Considering a network of neutron-rich C–N–O isotopes, we show the effect on abundance calculations in a neutrino-driven wind environment of a core-collapse supernova at two critical temperatures T 9 = 3.4 and 0.62. The results are compared for nuclear physics inputs sourced from the FRDWBA, statistical estimates, and standard databases. At temperatures T 9 = 3.4, where alpha capture, or at T 9 = 0.62, where the neutron capture dominates, one can distinguish the effect of accounting for the exotic nature of the nuclei involved. Furthermore, we assess the impact of varying neutron capture and photodisintegration rates involving halo or bubble structures on the abundances within the network.

Empirically tuned theory reveals why symbiont abundance 'mite' vary across hosts.

Research Highlight: del Mar Labrador, M., Serrano, D., Doña, J., Aguilera, E., Arroyo, J. L., Atiénzar, F., Barba, E., Bermejo, A., Blanco, G., Borràs, A., Calleja, J. A., Cantó, J. L., Cortés, V., de la Puente, J., de Palacio, D., Fernández-González, S., Figuerola, J., Frías, Ó., Fuertes-Marcos, B. Garamszegi, L. Z., Gordo, Ó., Gurpegui, M., Kovács, I., Martínez, J. L., Meléndez, L., Mestre, A., Møller, A. P., Monrós, J. S., Moreno-Opo, R., Navarro, C., Pap, P. L., Pérez-Tris, J., Piculo, R., Ponce, C., Proctor, H., Rodríguez, R., Sallent, Á., Senar, J., Tella, J. L., Vágási, C. I., Vögeli, M., & Jovani, R. (2023). Host space, not energy or symbiont size, constrains feather mite abundance across passerine bird species. Journal of Animal Ecology, https://doi.org/10.1111/1365-2656.14032. Symbionts represent crucial links between species in ecosystems. Consequently, understanding their patterns of abundance is a major goal in the study of symbioses. However, multiple biotic and abiotic factors may regulate symbionts, and disentangling the mechanisms that drive variation in their abundance across host species is challenging. One promising strategy to approach this challenge is to incorporate biologically relevant data into theoretical models. In a recent study, Labrador etal. (2023) used this strategy to investigate the poorly understood symbiosis between feather mites and their avian hosts. They integrate a remarkable amount of empirical data with models based on the metabolic theory of ecology to determine what factors limit feather mite abundance across European passerines. Their quantitative analyses indicate that the number of feather barbs limits mite abundance across host species, suggesting that mite populations are spatially, but not energetically, constrained. These findings not only reveal mechanisms that may drive the variation in feather mite abundances across hosts, but also advance our understanding of the ecology of interspecific interactions more generally.

What's good for fish is good for fishes: Interspecific consistency of growth, condition, and abundance among glacial lakes

AbstractObjectiveFish abundance and growth are regulated by a combination of bottom‐up and top‐down forces, but many management techniques depend more heavily on the latter. Here, we evaluated whether intersystem variation in nutrient loading and bottom‐up forces play more dominant roles in the control of abundance and growth of species across similar lakes than intra‐ and interspecific compensatory effects. We aimed to assess whether patterns of abundance and growth are consistent among fish species across lakes.MethodsWe tested this by evaluating pairwise comparisons of catch‐per‐unit‐effort, condition, and length‐at‐age data for 11 common warmwater fish species from 184 mesotrophic and eutrophic glacial lakes in Indiana, United States. We characterized the environmental conditions of each lake using limnological measurements (e.g., chlorophyll‐a concentration and surface temperature), lake morphology descriptions (e.g., depth and size), catchment characteristics (e.g., percent agricultural land cover), and nutrient load modeling using the Long‐Term Hydrologic Impact Analysis model. Taking a meta‐analysis approach, we used effect size calculation from pairwise correlations among lakes to identify environmental and community impacts on species abundance, condition, and length at age.ResultWe demonstrated that there were positive associations among most species comparisons (i.e., multiple species experiencing relatively fast growth in the same lake). Evaluations of environmental conditions among systems suggested that differences in estimated phosphorus input and the limnological measurements of total phosphorus, Secchi depth, and chlorophyll‐a concentration were good predictors of length at age and catch per unit effort for fish.ConclusionOur results indicated that there is a strong and consistent influence of environmental conditions and bottom‐up processes in determining species abundance and growth. This suggests that bottom‐up forces and environmental conditions linked to nutrient loading likely determine the upper boundary of fish abundance and growth in these lakes.

Spatial prey availability and pulsed reproductive tactics: Encounter risk in a canid-ungulate system.

Predation risk is a function of spatiotemporal overlap between predator and prey, as well as behavioural responses during encounters. Dynamic factors (e.g. group size, prey availability and animal movement or state) affect risk, but rarely are integrated in risk assessments. Our work targets a system where predation risk is fundamentally linked to temporal patterns in prey abundance and behaviour. For neonatal ungulate prey, risk is defined within a short temporal window during which the pulse in parturition, increasing movement capacity with age and antipredation tactics have the potential to mediate risk. In our coyote-mule deer (Canis latrans-Odocoileus hemionus) system, leveraging GPS data collected from both predator and prey, we tested expectations of shared enemy and reproductive risk hypotheses. We asked two questions regarding risk: (A) How does primary and alternative prey habitat, predator and prey activity, and reproductive tactics (e.g. birth synchrony and maternal defence) influence the vulnerability of a neonate encountering a predator? (B) How do the same factors affect behaviour by predators relative to the time before and after an encounter? Despite increased selection for mule deer and intensified search behaviour by coyotes during the peak in mule deer parturition, mule deer were afforded protection from predation via predator swamping, experiencing reduced per-capita encounter risk when most neonates were born. Mule deer occupying rabbit habitat (Sylvilagus spp.; coyote's primary prey) experienced the greatest risk of encounter but the availability of rabbit habitat did not affect predator behaviour during encounters. Encounter risk increased in areas with greater availability of mule deer habitat: coyotes shifted their behaviour relative to deer habitat, and the pulse in mule deer parturition and movement of neonatal deer during encounters elicited increased speed and tortuosity by coyotes. In addition to the spatial distribution of prey, temporal patterns in prey availability and animal behavioural state were fundamental in defining risk. Our work reveals the nuanced consequences of pulsed availability on predation risk for alternative prey, whereby responses by predators to sudden resource availability, the lasting effects of diversionary prey and inherent antipredation tactics ultimately dictate risk.

Insight into planktonic protistan and fungal communities across the nutrient-depleted environment of the South Pacific Subtropical Gyre.

Ocean microorganisms constitute ~70% of the marine biomass, contribute to ~50% of the Earth's primary production, and play a vital role in global biogeochemical cycles. The marine heterotrophic and mixotrophic protistan and fungal communities have often been overlooked mainly due to limitations in morphological species identification. Despite the accumulation of studies on biogeographic patterns observed in microbial communities, our understanding of the abundance and distribution patterns within the microbial community of the largest subtropical gyre, the South Pacific Gyre (SPG), remains incomplete. Here, we investigated the diversity and vertical composition of protistan and fungal communities in the water column of the ultra-oligotrophic SPG. Our results showed apparent differences in protistan community diversity in the photic and aphotic regions. The entire protistan community diversity was significantly affected by temperature, salinity, oxygen, and nutrient concentrations, while the parasitic community diversity was also affected by chlorophyll a concentration. The parasitic protists were assigned to the class Syndiniales accounting for over 98% of the total parasitic protists, exhibiting higher relative sequence abundance along the water depth and displaying consistent patterns among different sampling stations. In contrast to the protistan community, the fungal community along the SPG primarily clustered based on the sampling station and pelagic zones. In particular, our study reveals a significant presence of parasitic protists and functionally diverse fungi in SPG and their potential impact on carbon cycling in the gyre.IMPORTANCEOur findings carry important implications for understanding the distribution patterns of the previously unrecognized occurrence of parasitic protists and functionally diverse fungi in the nutrient-limited South Pacific Gyre. In particular, our study reveals a significant presence of parasitic Syndiniales, predominantly abundant in the upper 300 m of the aphotic zone in the gyre, and a distinct presence of fungal communities in the aphotic zone at the central part of the gyre. These findings strongly suggest that these communities play a substantial role in yet insufficiently described microbial food web. Moreover, our research enhances our understanding of their contribution to the dynamics of the food webs in oligotrophic gyres and is valuable for projecting the ecological consequences of future climate warming.

Population size and factors influencing the distribution of the urban pigeon Columba livia f. domestica in Pamplona

The environmental and trophic conditions of cities often give rise to very large populations of urban pigeons Columba livia f. domestica, which can cause local health and heritage problems due to accumulations of their droppings. Estimating the size of pigeon populations and defining their spatial patterns of abundance are therefore crucial for effective pigeon management in built-up areas. This article estimates the abundance of pigeons in Pamplona and the factors that explain the variability of pigeon abundance at local level. The Random Forest model of abundance at a local scale of 0.25 km2 cells had very high explanatory power, although its predictive power decreased due to this species’ gregariousness. Abundance decreased with increasing distance from the city centre, and from historic buildings and large parks, but increased as the proportion of the area covered by parks and built-up areas increased. The rock pigeon population in Pamplona was estimated at 8,030 individuals (95% CI: 6,483–9,860). The estimated density of urban pigeons for Pamplona as a whole was, on average, 218 birds/km2, although this figure varied considerably between habitats and areas: the highest values were measured in urban areas with historic buildings (exceeding 600 individuals/km2; in 35.8% of the 0.25 km2 cells, more than 200 individuals were estimated). Pigeon densities fell to ca. 250 birds/km2 in urban areas lacking large parks or green spaces whether near or far from historic buildings. In the peri-urban areas (i.e. arable fields, scrub and woodland), densities decreased to around 10–50 individuals/km2. In the city of Pamplona, although the population density of urban pigeons did not reach the numbers observed in other northern Spanish cities such as Barcelona, the habitat preference patterns in urban gradients are consistent with those documented in other European regions. We identify specific urban areas for population control and recommend measures such as feeding bans and waste and facade management to make it difficult for urban pigeons to access roosting and breeding sites in buildings.

KPM: A Flexible and Data-driven K-process Model for Nucleosynthesis

The element abundance pattern found in Milky Way disk stars is close to two-dimensional, dominated by production from one prompt process and one delayed process. This simplicity is remarkable, since the elements are produced by a multitude of nucleosynthesis mechanisms operating in stars with a wide range of progenitor masses. We fit the abundances of 14 elements for 48,659 red-giant stars from APOGEE Data Release 17 using a flexible, data-driven K-process model—dubbed KPM. In our fiducial model, with K = 2, each abundance in each star is described as the sum of a prompt and a delayed process contribution. We find that KPM with K = 2 is able to explain the abundances well, recover the observed abundance bimodality, and detect the bimodality over a greater range in metallicity than has previously been possible. We compare to prior work by Weinberg et al., finding that KPM produces similar results, but that KPM better predicts stellar abundances, especially for the elements C+N and Mn and for stars at supersolar metallicities. The model fixes the relative contribution of the prompt and delayed processes to two elements to break degeneracies and improve interpretability; we find that some of the nucleosynthetic implications are dependent upon these detailed choices. We find that moving to four processes adds flexibility and improves the model’s ability to predict the stellar abundances, but does not qualitatively change the story. The results of KPM will help us to interpret and constrain the formation of the Galaxy disk, the relationship between abundances and ages, and the physics of nucleosynthesis.

Using Drones to Reveal the Distribution and Population Abundance of Threatened Dasyatid Rays at a Nursery Site in Seychelles

Drones are becoming increasingly valuable tools for studying species in marine environments. Here, a consumer-grade drone was used to elucidate the distribution and population abundance of two threatened dasyatid rays, Pastinachus ater and Urogymnus granulatus, in a remote marine protected area in the Republic of Seychelles. Over six weeks in March and April 2023, a total of 80 survey flights, covering an area of 3.2 km2, recorded 1262 P. ater and 822 U. granulatus. Findings revealed previously unresolved high-use areas for both species, which almost exclusively used sandy areas within the habitat and were found in greater abundances in areas closer to the shoreline. Spatial patterns in abundance were strongly correlated between species, with both often found in mixed-species groups. The site was shown to support large populations of both species with total population abundance estimates of 2524 (2029–3019 95% CI, 0.1 CV) for P. ater and 2136 (1732–2539 95% CI, 0.09 CV) for U. granulatus. This study highlights the applicability of drones in acquiring highly useful data for delineating critical habitats and informing the adaptive management of marine protected areas.

Horizontal migration of zooplankton in lake–wetland interfaces. Can temperature-driven surface exchange flows modulate its patterns?

Lake ecology can be affected by exchange flows driven by horizontal temperature gradients in lake–wetland interfaces. In this work, we investigate the hypothesis that thermally driven flows modulate the horizontal migration patterns of freshwater zooplankters. A 48-h field campaign in a shallow lake (Lake Vela, Quiaios, Portugal) was carried out to test this hypothesis. Thermal differences between the littoral and limnetic areas were measured along two transects featuring a Schoenoplectus lacustris and a Myriophyllum aquaticum stand in the littoral. In parallel, the physiochemistry and chlorophyll a, as a proxy for food availability differences between the littoral and the limnetic zones, were monitored. Zooplankton samples were collected for assessing overall and group-specific number-density differences. The diel period (day or night) and the site (littoral or limnetic zone) did not interact significantly to modulate the variation patterns for the studied physiochemical variables, indicating that these parameters should not explain horizontal zooplankton distribution patterns. The expected patterns for zooplankton diel horizontal migration as driven by the presence of visual predators were occasionally confirmed by our limnetic versus littoral abundance records through time, depending on the transect. Group-specific abundance patterns indicate particular features: copepods always preferred the littoral over the limnetic zone regardless of the diel period; chydorids always preferred the littoral zone regardless of the macrophyte stand involved; bosminids tended to preferentially concentrate in the limnetic zone. No consistent relationship was identified between the expected flow direction due to temperature differences and zooplankton abundance changes, although it occasionally occurred through the dataset.

Mangrove gastropod distribution based on dominant vegetation classes and their relationship with physicochemical characteristics on fringe mangroves of Lembongan Island, Bali, Indonesia

Abstract. Ernawati NM, Dewi APWK, Sugiana IP, Dharmawan IWE, Ma’ruf MS, Galgani GA. 2024. Mangrove gastropod distribution based on dominant vegetation classes and their relationship with physicochemical characteristics on fringe mangroves of Lembongan Island, Bali, Indonesia. Biodiversitas 25: 156-166. Mangrove ecosystems are important in supporting diverse marine life, offering refuge, reproductive grounds, and sustenance to various species. However, mangroves possess distinct zoning patterns determined by dominant species due to environmental variations that significantly impact the biodiversity of biota, particularly gastropods. A study on the Indonesian island of Nusa Lembongan revealed distinct communities of coexisting gastropod species in each mangrove vegetation zone. We discovered 29 distinct species of mangrove gastropods, with the Sonneratia mangrove zone having the most and the Lumnitzera zone having the least. Certain species, including Amphidromus perversus, Cerithium adustum, and Echinolittorina sundaica, were detected in only one of the mangrove zones. In each mangrove zone, the composition of gastropod species changed depending on the substrate type, e.g., soil, mangrove trunks, or mangrove leaves. The Shannon-Wiener diversity index values range from low to high diversity, and the community structure index values in mangrove zones vary. The evenness index varied by region, with Avicennia, Bruguiera, and Sonneratia having the highest index value. The findings indicate that mangrove vegetation zones are essential for maintaining diverse gastropod populations, with distinct composition and abundance patterns influenced by the distance of each mangrove zone from the ocean. This data may influence conservation efforts to preserve mangrove habitats and the diverse array of organisms that depend on them.