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Summary: Crowdsourcing methods facilitate the production of scientific information by non‐experts. This form of citizen science (CS) is becoming a key source of complementary data in many fields to inform data‐driven decisions and study challenging problems. However, concerns about the validity of these data often constrain their utility. In this paper, we focus on the use of citizen science data in addressing complex challenges in environmental conservation. We consider this issue from three perspectives. First, we present a literature scan of papers that have employed Bayesian models with citizen science in ecology. Second, we compare several popular majority vote algorithms and introduce a Bayesian item response model that estimates and accounts for participants' abilities after adjusting for the difficulty of the images they have classified. The model also enables participants to be clustered into groups based on ability. Third, we apply the model in a case study involving the classification of corals from underwater images from the Great Barrier Reef, Australia. We show that the model achieved superior results in general and, for difficult tasks, a weighted consensus method that uses only groups of experts and experienced participants produced better performance measures. Moreover, we found that participants learn as they have more classification opportunities, which substantially increases their abilities over time. Overall, the paper demonstrates the feasibility of CS for answering complex and challenging ecological questions when these data are appropriately analysed. This serves as motivation for future work to increase the efficacy and trustworthiness of this emerging source of data. [ABSTRACT FROM AUTHOR]

Denitrification is a key process in the global nitrogen (N) cycle, causing both nitrous oxide (N2O) and dinitrogen (N2) emissions. However, estimates of seasonal denitrification losses (N2O + N2) are scarce, reflecting methodological difficulties in measuring soil‐borne N2 emissions against the high atmospheric N2 background and challenges regarding their spatio‐temporal upscaling. This study investigated N2O + N2 losses in response to N fertilizer rates (0, 100, 150, 200, and 250 kg N ha−1) on two intensively managed tropical sugarcane farms in Australia, by combining automated N2O monitoring, in situ N2 and N2O measurements using the 15N gas flux method and fertilizer 15N recoveries at harvest. Dynamic changes in the N2O/(N2O + N2) ratio (<0.01 to 0.768) were explained by fitting generalized additive mixed models (GAMMs) with soil factors to upscale high temporal‐resolution N2O data to daily N2 emissions over the season. Cumulative N2O + N2 losses ranged from 12 to 87 kg N ha−1, increasing non‐linearly with increasing N fertilizer rates. Emissions of N2O + N2 accounted for 31%–78% of fertilizer 15N losses and were dominated by environmentally benign N2 emissions. The contribution of denitrification to N fertilizer loss decreased with increasing N rates, suggesting increasing significance of other N loss pathways including leaching and runoff at higher N rates. This study delivers a blueprint approach to extrapolate denitrification measurements at both temporal and spatial scales, which can be applied in fertilized agroecosystems. Robust estimates of denitrification losses determined using this method will help to improve cropping system modeling approaches, advancing our understanding of the N cycle across scales. Plain Language Summary: Denitrification is a soil nitrogen (N) transformation process, producing the potent greenhouse gas (GHG) nitrous oxide (N2O), while turning reactive N into environmentally benign dinitrogen (N2). The response of these N losses to N fertilizer inputs is critical to reduce environmental impacts while maintaining crop productivity in agriculture. However, difficulties in measuring soil‐borne N2 against atmospheric N2 and upscaling of these emissions to the farm scale hinder estimation of denitrification losses, leaving denitrification as a major uncertainty for N budgets. This study quantified denitrification losses in response to N fertilizer rates on sugarcane farms in Australia, by combining automated GHG monitoring systems, N isotope techniques and statistical models. This unique approach demonstrated denitrification as a major N loss pathway, increasing nonlinearly with increasing N rates. Fertilizer N budgets showed that environmentally harmful N losses increased more than proportionally with N inputs. These findings emphasize that excessive N fertilizer use leads to agronomic inefficiency with severe adverse effects on the surrounding ecosystems such as the Great Barrier Reef. The novel approach presented here will advance our understanding of N cycling across scales and thus aid in reducing the environmental footprint of global agricultural production. Key Points: A novel method to estimate N2O + N2 losses by combining high‐frequency N2O data, in situ 15N gas flux measurements and fertilizer 15N recoveriesDenitrification losses of 12–87 kg N ha−1 were dominated by N2 (>94%) and increased non‐linearly with increasing N ratesDenitrification accounted for 31%–78% of N fertilizer losses while the proportion of reactive N losses increased with increasing N rates [ABSTRACT FROM AUTHOR]

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Complex color patterning is a characteristic feature of dwarf minke whales (DMWs; Balaenoptera acutorostrata) which has been used to photographically identify (photo‐ID) individuals and to research an aggregation on Australia's Great Barrier Reef (GBR). DMW color patterns have been described and applied in various studies, but a detailed and systematic analysis of their complexity is yet to be performed. Here, we applied a novel categorization tool to assess the variation, asymmetry, and association of several DMW color pattern elements, subelements, and their character states. Proportions, hierarchical clustering, and multiple correspondence analysis revealed a high level of asymmetric color pattern variation, with white markings dominant and associated on the right of the body. Our results will improve the citizen science driven photo‐ID of this little‐known cetacean as labor‐intensive manual methods transition to more efficient automated approaches. Such advancement will be challenging, yet beneficial for broader research into the poorly understood areas of DMW life history, evolution, genetics, social structure, and feeding. This could also potentially allow investigation into the functional significance of their color patterns. [ABSTRACT FROM AUTHOR]

The Nullarbor Plain is a ~200,000 km2 planar karst surface in southern Australia, underlain by Cenozoic shallow‐water limestones. During the Miocene the area was uplifted, and although the plain is generally considered extremely flat, locally, the geomorphology of the Nullarbor Plain retains evidence of earth surface processes across a long, middle Miocene‐to‐present time span. The accessibility of the recent 0.4 arc‐second TanDEM‐X digital elevation model (DEM) by the German Aerospace Centre motivated the search for other possible fine‐scale landforms that would previously have been unresolvable. The analysis of DEM images revealed an enigmatic annular landform with an outer diameter between 1200 m and 1300 m. It consists of a circular elevated rim and a central dome. Its morphology is distinct from other landforms observed on the plain, and cannot be readily explained as a part of known active or inferred/expected processes on the plain (e.g., fluvial, aeolian, karst, tectonic or extra‐terrestrial impact processes). More recent karst processes (dayas formation) overprinting the landform indicates the presence of the annular structure prior to dayas formation. A unique microbial boundstone facies sampled from the bed‐rock of the annular structure supports an interpretation of long‐lived, at least partial retention of a primary depositional structure. Differential carbonate deposition, especially bioherm growth, was a likely origin of the annular topographical expression of the present‐day landform and is comparable to biogenic structures in the modern day deeper Great Barrier Reef. [ABSTRACT FROM AUTHOR]

Angiosperms have co‐evolved with animals over thousands of years leading to an array of mutualistic relationships. Passage of plant seeds through animal intestines leads to an important mutualism providing the animal with food and the plant with seed dispersal and enhanced germination. This phenomenon is well studied in terrestrial angiosperms, but there is less research in aquatic environments. We studied the effect of gut passage in marine mega‐herbivores (green sea turtles and dugongs) on seed germination for a common Australian seagrass, Zostera muelleri. We collected fecal samples likely to contain seeds, as well as seagrass seeds from plants at two coastal seagrass meadows in the central Great Barrier Reef World Heritage Area, Australia. Seeds collected from feces and plants were subjected to germination trials across different temperature treatments: low (19°C), medium (26°C), and high (32°C). We found excreted seeds had a significantly greater germination probability (two to four times greater) and germinated significantly faster (18–61% faster) than seeds from the plant. Excreted seeds which had not germinated at the end of the experiment were significantly less likely to be viable compared with seeds taken from the plant. Seeds released from the plant have a slow germination and low germination probability compared with excreted seeds, but retain a high percentage of seed viability. Our study is the first record of marine mega‐herbivores enhancing germination of Z. muelleri seeds. By transporting seeds to new locations and enhancing germination, these animals are important in seagrass resilience and connectivity among metapopulations. [ABSTRACT FROM AUTHOR]

Patterns of reproductive ontogeny in four species of coral reef wrasses (F: Labridae) Hemigymnus melapterus, Hemigymnus fasciatus, Cheilinus fasciatus and Oxycheilinus digramma were investigated. Populations of each species were sampled from two island groups of the central Great Barrier Reef (GBR), Australia, and from coral reefs in the central Philippines. These three sampling locations span 30° of latitude. The GBR and Philippine reefs experience biologically significant differences in water temperature, geography and human activity. The studied wrasses are effectively unfished in Australia but heavily fished in the Philippines. Gonad weights, histology and demographic data were obtained across the entire size and age range of H. melapterus, C. fasciatus and O. digramma from all locations. Analysis identified three processes of male recruitment: functional gonochorism and both forms of protogynous hermaphroditism, monandry and diandry. The expression of these distinct sexual ontogenies was locality dependent. Populations of H. melapterus, H. fasciatus, C. fasciatus and O. digramma on the GBR showed consistently uniform patterns of sexual ontogeny, with all species being exclusively monandric. H. melapterus, C. fasciatus and O. digramma in the Philippines displayed complex sexual ontogenies, with all species showing histological evidence of both diandry and functional gonochorism. Reproductive investment in gonadal tissue, and population sex structure, also differed between GBR and Philippine coral reefs. Philippine populations had substantially lower gonado‐somatic indices than populations on the GBR. Nonetheless, Philippine populations matured more rapidly and displayed a protracted timing of sex change over a large size and age range. Thus, mature females appeared earlier and persisted later into ontogeny in the Philippines than on GBR reefs. Protracted timing of sex change on Philippine reefs is likely linked to the presence of primary males in the population, which is known to reduce the strength of selection for mature females to undergo sex change and become male. Hypotheses based on social structure of fish populations, environmental factors and evolutionary history were developed to account for the different patterns of sexual ontogeny in the focal wrasses. [ABSTRACT FROM AUTHOR]