Migratory Species Research Articles

Combining thinning and diverse plantings to adapt to climate-change-induced timber supply shortage in British Columbia

Forestry is an important component of Canada’s economy with British Columbia (BC) contributing almost half to the national roundwood production. Yet, the country’s timber supply and forest economy are threatened by climate change, with increased frequency and severity of natural disturbances and changes in forest productivity. Mountain pine beetle ( Dendroctonus ponderosae) outbreaks are endemic in BC, but the latest climate change-driven outbreak has resulted in a cumulative loss of over half of all merchantable pine, leading to a mid-term timber supply shortage. In this study, we investigate the potential of commercial thinning and alternative planting regimes based on species diversification and assisted species migration to mitigate the anticipated decrease in timber supply in BC. We simulated the long-term effects of these management options in a case study area in interior BC, using a toolbox that combines management- and research-oriented data and models. We found that combining commercial thinning and species diversification has the best potential to mitigate future timber supply shortages in BC. We discuss the limits of this toolbox approach and identify research needs and recommendations for future studies aiming at modelling cumulative effects of management, climate change, and natural disturbances on timber supply.

Closing the gap: examining the impact of source habitat proximity on plant and soil microbial communities in post-mining spoil heap succession.

Revegetation of barren substrates is often determined by the composition and distance of the nearest plant community, serving as a source of colonizing propagules. Whether such dispersal effect can be observed during the development of soil microbial communities, is not clear. In this study, we aimed to elucidate which factors structure plant and soil bacterial and fungal communities during primary succession on a limestone quarry spoil heap, focusing on the effect of distance to the adjoining xerophilous grassland. We established a grid of 35 plots covering three successional stages - initial barren substrate, early successional community and late successional grassland ecosystem, the latter serving as the primary source of soil colonization. On these plots, we performed vegetation surveys of plant community composition and collected soil cores to analyze soil chemical properties and bacterial and fungal community composition. The composition of early successional plant community was significantly affected by the proximity of the source late successional community, however, the effect weakened when the distance exceeded 20 m. Early successional microbial communities were structured mainly by the local plant community composition and soil chemical properties, with minimal contribution of the source community proximity. These results show that on small spatial scales, species migration is an important determinant of plant community composition during primary succession while the establishment of soil microbial communities is not limited by dispersal and is primarily driven by local biotic and abiotic conditions.

Photothermal Synergistic Effect Induces Bimetallic Cooperation to Modulate Product Selectivity of CO2 Reduction on Different CeO2 Crystal Facets

AbstractProduct selectivity of solar‐driven CO2 reduction and H2O oxidation reactions has been successfully controlled by tuning the spatial distance between Pt/Au bimetallic active sites on different crystal facets of CeO2 catalysts. The replacement depth of Ce atoms by monatomic Pt determines the distance between bimetallic sites, while Au clusters are deposited on the surface. This space configuration creates a favourable microenvironment for the migration of active hydrogen species (*H). The *H is generated via the activation of H2O on monatomic Pt sites and migrate towards Au clusters with a strong capacity for CO2 adsorption. Under concentrated solar irradiation, selectivity of the (100) facet towards CO is 100 %, and the selectivity of the (110) and (111) facets towards CH4 is 33.5 % and 97.6 %, respectively. Notably, the CH4 yield on the (111) facet is as high as 369.4 μmol/g/h, and the solar‐to‐chemical energy efficiency of 0.23 % is 33.8 times higher than that under non‐concentrated solar irradiation. The impacts of high‐density flux photon and thermal effects on carriers and *H migration at the microscale are comprehensively discussed. This study provides a new avenue for tuning the spatial distance between active sites to achieve optimal product selectivity.

Prominent differences in the adsorption and substitution characteristics of As(III) and As(V) on gypsum during wet flue gas desulfurization

Arsenic-bearing gypsum (ABG) is a hazardous by-product of wet flue gas desulfurization (FGD) and must be strictly controlled. This study investigated the migration of arsenic species during wet FGD and proposed strategies to reduce the toxicity of FGD gypsum in operation. During gypsum crystallization, the adsorption and substitution characteristics of As(III) and As(V) exhibit significant differences. The amount of As(III) captured by CaSO4·2H2O is greater than that of As(V). The As(III) adsorbed on the growth surface of CaSO4·2H2O can be incorporated into the gypsum by substituting for SO42−, while As(V) tends to remain adsorbed on the surface. Moreover, the arsenic adsorption capacity of the incompletely oxidized product CaSO3·0.5H2O was almost three times that of CaSO4·2H2O, especially for As(III). Based on the differences in the migration characteristics of As(III) and As(V), a strategy was proposed to reduce the arsenic content and biotoxicity in gypsum during operation by enhancing the oxidation of sulfite and highly toxic arsenite, thus ensuring the safe utilization of FGD gypsum.

Preparation of a finely dispersion nickel-based in-situ pyrolysis catalyst: Influence of lignocellulosic constituents

Metal/biochar catalysts could be synthesized via directly subjecting biomass impregnated with metal salts to pyrolysis. The properties of biochar are intricately linked to the inherent composition of the raw material, which in turn could influence the degree of metal dispersion and its catalytic impact. The poplar sawdust and its fractioned proportion was employed for the preparation of Ni-based biochar catalysts. The work mainly focuses on the impact of lignocellulosic material with diverse compositions on the dispersion of nickel particles during the calcination-pyrolysis co-process. Given that cellulose and holocellulose constituted the majority of the material, the matching catalyst support may encourage the migration of nickel species to produce substantial amounts of particles, perhaps as a result of several reactions such as dehydration and aromatization. In contrast, the utilization of sawdust as a support demonstrated a remarkable effect in dispersing nickel particles, nickel particle size and H2 uptake were 7.0nm and 19.8 μmol/g, respectively, while also displaying exceptional catalytic activity in the hydrogenation of vanillin, with the maximum conversion and 2-methoxy-4-methylphenol (MMP) yield of 99.7% and 69.0%. It has been determined that the presence of lignin in the system has a beneficial impact on the dispersion of nickel and its catalytic activity.

Using Genetic Data to Determine Origin for Out-Migrating Smolt and Returning Adult Steelhead Trout (Oncorhynchus mykiss) in a Southeast Alaska Drainage.

Oncorhynchus mykiss is a partially migratory salmonid species, and many migratory populations (known as steelhead) have declined in recent decades in the western United States and Canada. Closely related resident populations (known as rainbow trout) may be an effective resource in the recovery of these declining migratory populations. However, the extent to which different populations of resident rainbow trout produce migratory individuals and how likely these individuals are to return as adults to spawn remains unknown. One limitation to answering these questions is the identification of loci that accurately segregate between migratory and resident populations. To address this limitation, we used existing genomic data from a well-studied population of O. mykiss from Southeastern Alaska (Sashin Creek) to identify loci that segregate between phenotypes. We then utilized Double Mismatch Allele-Specific qPCR (DMAS-qPCR) to genotype 233 smolts out-migrating from Sashin Creek and 99 returning adult steelhead trout across a five-year period to determine (a) the origin of out-migrating smolts and returning adults and (b) to quantify the extent to which the resident population contributes to the migratory population. Our results show that 37.3% of out-migrating smolts were produced from resident parents, whereas 19.3% of returning adults had resident parents. Ultimately, these results demonstrate that resident populations of rainbow trout produce migrant offspring that successfully complete their migration and return to spawn, increasing population sizes and likely improving genetic diversity. Therefore, conservation efforts should consider landlocked resident populations for producing smolts when developing recovery plans for migratory steelhead populations.

Atlantic bluefin tuna tagged off Norway show extensive annual migrations, high site-fidelity and dynamic behaviour in the Atlantic Ocean and Mediterranean Sea.

Atlantic bluefin tuna (ABFT; Thunnus thynnus) is a highly migratory species. To investigate the migrations and vertical behaviours of ABFT migrating to Nordic waters, we deployed pop-up satellite archival transmitting tags on 25 ABFT off Norway (curved fork length: 228-292 cm). We obtained 16 full-year migrations, which differed between individuals, and physically recovered 13 tags, which provided 4699 days of archival depth and temperature data. ABFT occupied waters from the Arctic Circle to as far south as Cabo Verde, Africa, and occupied depths down to 1190 m and temperatures from 0.5 to 27.8°C. During their annual migrations, ABFT spent, on average, 68 days in Norwegian waters, 65 days in the Newfoundland Basin, 35 days around the Canary Islands and 33 days in the West European Basin. Most ABFT entered the Mediterranean Sea with a mean entry date of 13 May and visited known spawning grounds, staying, on average, 44 days. All ABFT with full-year deployments returned to Norwegian waters. ABFT displayed high site-fidelity and dynamic vertical diving behaviours that varied between hotspots and seasons. These spatiotemporal data provide important ecological knowledge for sustainable management and the conservation of the recently recovered eastern ABFT stock.

Genetic Stock Identification Reveals Mismatches Between Management Areas and Population Genetic Structure in a Migratory Pelagic Fish.

Sustainable fisheries management is important for the continued harvest of the world's marine resources, especially as they are increasingly challenged by a range of climatic and anthropogenic factors. One of the pillars of sustainable fisheries management is the accurate identification of the biological units, i.e., populations. Here, we developed and implemented a genetic baseline for Atlantic herring harvested in the Norwegian offshore fisheries to investigate the validity of the current management boundaries. This was achieved by genotyping > 15,000 herring from the northern European seas, including samples of all the known populations in the region, with a panel of population-informative SNPs mined from existing genomic resources. The final genetic baseline consisted of ~1000 herring from 12 genetically distinct populations. We thereafter used the baseline to investigate mixed catches from the North and Norwegian Seas, revealing that each management area consisted of multiple populations, as previously suspected. However, substantial numbers (up to 50% or more within a sample) of herring were found outside of their expected management areas, e.g., North Sea autumn-spawning herring north of 62° N (average = 19.2%), Norwegian spring-spawning herring south of 62° N (average = 13.5%), and western Baltic spring-spawning herring outside their assumed distribution area in the North Sea (average = 20.0%). Based upon these extensive observations, we conclude that the assessment and management areas currently in place for herring in this region need adjustments to reflect the populations present. Furthermore, we suggest that for migratory species, such as herring, a paradigm shift from using static geographic stock boundaries towards spatial dynamic boundaries is needed to meet the requirements of future sustainable management regimes.

Behavioural responses of a trans-hemispheric migrant to climate oscillation.

Large-scale climatic fluctuations, such as the El Niño-Southern Oscillation, can have dramatic effects on ocean ecosystem productivity. Many mobile species breeding in temperate or higher latitudes escape the extremes of seasonal climate variation through long-distance, even trans-global migration, but how they deal with, or are affected by, such longer phased climate fluctuations is less understood. To investigate how a long-lived migratory species might respond to such periodic environmental change we collected and analysed a 13 year biologging dataset for a trans-equatorial migrant, the Manx shearwater (Puffinus puffinus). Our primary finding was that in El Niño years, non-breeding birds were at more northerly (lower) latitudes than in La Niña years, a response attributable to individual flexibility in migratory destinations. Daily time spent foraging varied in concert with this latitudinal shift, with birds foraging less in El Niño years. Secondarily, we found that in subsequent breeding, a hemisphere away, El Niño years saw a reduction in foraging time and chick provisioning rates: effects that could not be attributed to conditions at their breeding grounds in the North Atlantic. Thus, in a highly migratory animal, individuals may adjust to fluctuating non-breeding conditions but still experience cascading carry over effects on subsequent behaviour.

Biodiversity conservation and restoration of wetlands in suburban areas: challenges and prospects

Context Wetland loss threatens global biodiversity. Peri-urban wetlands face acute pressures from urban expansion. Aims Investigate biodiversity and land-cover changes in two wetlands undergoing suburbanisation near Hangzhou, China. Methods Seasonal field surveys of birds, fish and amphibians, coupled with remote-sensing analysis of land-cover changes from 2009 to 2020. Key results Suburban wetlands exhibited unique degradation patterns, including reduced species diversity, simplified community structures and proliferation of invasive species, with 91 bird species being recorded, dominated by common residents, 25 still-water fish species with few carnivores and migratory species, and 5 ubiquitous amphibian species detected. Species richness was lower than in nearby conserved wetlands. From 2009 to 2020, 6–7% of the wetlands were lost to urban expansion and converted to artificial vegetation or infrastructure. Conclusions Ecological degradation is driven by rapid urbanisation, with habitats being fragmented by roads and converted to artificial land covers. Water pollution from insufficient treatment and abandoned aquaculture further impairs habitats. Implications Innovative integrated-management framework was proposed for wetlands biodiversity restoration in suburban area. Key strategies include (1) modernising traditional circular economies to sustain wise use, (2) wildlife-friendly infrastructure design, (3) targeted invasive species control, and (4) adaptive co-management informed by ongoing monitoring. This socio-ecological systems approach aims to harmonise biodiversity conservation, cultural heritage and sustainable development in threatened suburban wetlands.

Fish Diversity of East Sea Streams in Nakdong River Region

Fish surveys were conducted near artificial structures installed in eight streams flowing from the Nakdong River region to the east coast of Korea. As a result of the survey, a total of 20,000 individuals belonging to nine orders, 17 families, and 47 species were found. The dominant species was Zacco koreanus, and the subdominant species was Pungtungia herzi. Among the surveyed fish species, endangered species were Pseudobagrus brevicorpus (rank I) and Cottus hangiongensis (rank II). In addition, migratory fish species were Oncorhynchus keta, Plecoglossus altivelis, and Tribolodon hakonensis. As a result of community analysis, the highest diversity, dominance, richness, and evenness indices were Wangpi, Chuksan, Gokgang, and Janggi Stream respectively. The highest number of species was surveyed in Gokgang Stream (25 species). Alpha diversity, the number of species at each survey point in each stream, was the highest at a survey point in Wangpi Stream (20 species), and beta diversity, species at each stream survey point that does not overlap with nearby survey point, was the highest at survey points in Gokgang Stream (12 species). As a result of the similarity analysis, surveyed streams were divided into four groups: group 1 (Chuksan, Baeknok Stream), group 2 (Uljinnamdae, Wangpi, Yungdeokosip Steam), group 3 (Gokgang Stream), and group 4 (Janggi, Hoeya Stream). This study is expected to serve as basic data for managing the aquatic ecosystem of streams flowing from the Nakdong River region to the east coast.

Tracking animal movements via collaborative acoustic telemetry networks: Multiscale habitat use, phenology, and management insights.

Estuaries support diverse fish and invertebrate communities, including resident species that rely on estuarine habitats year-round and transient migratory species. The unique movement patterns of these animals connect habitats within and far beyond the estuary and are integrally linked to fisheries management objectives. With a focus on Chesapeake Bay, this study leveraged data from collaborative acoustic telemetry networks in the northwest Atlantic to assess habitat use and phenology of movements for seven species of fish (cownose rays, dusky sharks, smooth dogfish, alewife, striped bass, common carp, and blue catfish) and one invertebrate (horseshoe crabs). A total of 288 acoustically tagged individuals were detected >3.2 million times (6,743 to 2,095,717 detections per species) on receivers across ~20.5 degrees of latitude spanning the North American Atlantic seaboard from Florida, USA, to New Brunswick, Canada. Common metrics of movement and phenology grouped these species as resident (common carp, blue catfish, horseshoe crabs), primarily resident in estuaries (juvenile striped bass), and coastal migrant (cownose rays, dusky sharks, smooth dogfish, alewife); maximum distance traveled varied by three orders of magnitude among these species. Further analysis of phenology for coastal migrants elucidated the timing and duration of these species' use of Chesapeake Bay. Collectively, movements linked habitats within Chesapeake Bay and connected the estuary to coastal ecosystems both to the north (e.g., alewife) and south (e.g., cownose rays), creating networks of fisheries management jurisdictions that varied in complexity and identified opportunities for enhancement to current management or co-management of some species. Our results elucidate the importance of estuaries to species with diverse movement behaviors, identify scales and pathways of habitat connectivity via animal movements, and highlight the utility of collaborative acoustic telemetry networks for quantifying movements relevant to both ecological research and fisheries management.

Characterization of marine heat waves in the Iberia–Biscay–Ireland (IBI) region in 2022

Abstract. Marine heat waves (MHWs) are defined as prolonged periods of anomalously high sea surface temperatures. These events have a profound impact on marine ecosystems, resulting in ecological and economic impacts such as coral bleaching, reduced surface chlorophyll due to increased surface layer stratification, mass mortality of marine invertebrates due to heat stress, rapid species migrations, and fishery closures or quota changes, among others. This research focuses on the study of the MHWs that occurred in the IBI (Iberia–Biscay–Ireland) region during the year 2022, assessing their climatologic properties, analyzing the mean values for the year 2022, and discretizing the events in four subregions representative of the entire domain. Satellite-derived sea surface temperature data were used to detect and characterize the events, revealing that in some areas the year 2022 showed peak anomaly values of (i) 15 MHW events, (ii) 128 d of mean durations, and (iii) 261 total days of MHWs. Through observational and modeling data, the discrete events located in the Bay of Biscay were also examined in the subsurface layers, demonstrating a strong seasonal modulation and heat diffusion through deeper layers, where cold-season events reach higher MHW mean depth values and subsurface positive anomalies of temperature can remain for weeks once an MHW has ended.

Role of Climate Change in Altering Bird Migration Patterns in Vietnam

Purpose: The aim of the study was to analyze the role of climate change in altering bird migration patterns in Vietnam. Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: Climate change has significantly altered bird migration patterns in Vietnam, primarily due to shifting temperatures, altered precipitation patterns, and habitat loss. Warmer temperatures have caused many migratory birds to adjust their timing, either arriving earlier or delaying their departure, which often leads to mismatches with food availability and breeding conditions. Additionally, changes in rainfall patterns have impacted the availability of critical stopover sites, such as wetlands, which are essential for resting and refueling during migration. Habitat loss due to climate change and human activities has further compounded these challenges, threatening the survival of various bird species that rely on consistent migratory routes. Unique Contribution to Theory, Practice and Policy: Ecological niche theory, phenological mismatch theory & climate envelope theory may be used to anchor future studies on role of climate change in altering bird migration patterns in Vietnam. Conservation practices should focus on adaptive habitat management that accounts for the changing migration patterns of birds due to climate change. Policymakers should prioritize the development of climate-responsive conservation policies that explicitly address the impacts of climate change on migratory bird species.

Grassroots learning through indigenous co-design for a Kvmemongen in Coastal Lake Budi, Chile

ABSTRACT Given calls to decolonise engagement with Indigenous communities, this article explores how allied researchers can participate in self-determined learning with Indigenous Peoples. Drawing on over a decade of experience within an action-research collective in a Mapuche context, the authors suggest that allied researchers can accompany Indigenous-led co-design in a manner that not only strengthens genuine Indigenous participation but also fosters mutual and collective learning from within the co-creative processes themselves. Lake Budi, a biocultural hotspot in the Pacific coast of Northern Patagonia, Chile, is a coastal wetland habitat for hundreds of endemic and migratory species and the ancestral homeland for the Mapuche-Lafkenche (∼15,000) who, through grassroots learning, are determining practical steps towards restoring their territory and its self-governance for kvmemongen. This Mapuche concept refers broadly to enacting forms of living well together, humans and non-humans. As allied participants in a Mapuche-led codesign collective since 2013, in this paper, we focus on exploring key “moments of mutual learning” within this longer-than-usual co-design process. Each of these moments involved collective learning that required interaction and feedback loops across diverse areas of expertise, made possible over longer and flexible rhythms and periods. Tools, protocols, and methods gradually take shape in such a process through mutual learning opportunities provided by relationship building, cultural immersion, community-led protocols, decision-making, and evaluation mechanisms. This work suggests a new understanding of the involvement of allied researchers in Indigenous-led co-design as an emerging and increasingly relevant form of grassroots mutual learning toward climate resilience.

Dammed coastal waterways are less diverse, more homogenous, and dominated by non-native species: Comprehensive insights from quantitative analysis of environmental DNA

Small dams are commonplace worldwide and impact local and regional aquatic diversity by altering habitats and disrupting dispersal networks. Quantifying the local and regional impacts of dams requires nearly comprehensive species occurrence data. We used environmental DNA (eDNA) metabarcoding to test theoretical predictions about the impacts of dams on local and regional bony fish diversity within the Chesapeake Bay Watershed, USA. We analyzed eDNA from 465 sampling points within 34 waterbodies documenting the distributions of 61 species. On average, dammed waterbodies had approximately half (48 %) as many species per site as undammed (lower alpha diversity) and more homogenous species composition (lower beta diversity). Native migratory species were less than one tenth (0.08) as likely to be detected at dammed sites than undammed sites, native resident (non-migratory) species were one third (0.34) as likely, whereas introduced species were 2.6 times more likely to be detected. Our sampling and bioinformatics methods were validated by a diverse mock community control. Our results suggest that dams in coastal waterways homogenize fish metacommunities, reduce local biodiversity through dispersal limitation and habitat alteration, and favor the dominance of lentic-adapted introduced species while potentially restricting the spread of introduced catfish. Decisions to construct or decommission dams should consider local and regional impacts on biodiversity.

Winged odyssey: Profiling bacterial vistas in migratory avifauna via 16S rRNA sequencing

Avian migration is an intrinsic biological phenomenon that involves trans-boundary movements to evade adverse ecological circumstances. During migration, avian gut bacterial taxa may serve as a potential source of bacterial dissemination via fecal contamination at stop-over sites. Therefore, bacterial taxa composition as well as diversities were investigated employing 16S rRNA sequencing in fecal samples collected from flocks of seven migratory avian species visiting southern districts of Khyber Pakhtunkhwa, Pakistan. The analysis revealed that Grus virgo exhibits the highest alpha diversity, followed by Aythya ferina while G. grus reflects lowest diversity among all the migratory avian fecal samples. The findings depicted significant variations in the bacterial beta diversities of migratory avifauna. At phylum level, Firmicutes, Proteobacteria, and Actinobacteriota showed the highest relative abundance in Plegadis falcinellus, Chlamydotis undulata and Aythya ferina respectively. Further exploration within phyla elucidates finer-scale taxonomic differences at the family and genus levels. This study identified potential pathogenic bacteria such as Staphylococcus, Streptococcus, Enterococcus, Proteus, Clostridium sensu stricto 1, Fusobacterium and Escherichia that offers valuable insight into the microbiological hazards associated with migratory birds. Although pathogenicity was not directly assessed, the observed relative abundance of opportunistic bacterial genera suggests continuous surveillance of gut bacterial community during migration to safeguard avian biodiversity and mitigate escalating threats of infection emergence and dissemination.

Chromosomally located blaCMH in Enterobacter cloacae complex across human-bird-environment interfaces: A one-health perspective

To improve the understanding of antimicrobial resistance (AMR) in migratory birds derived-Enterobacter cloacae (E. cloacae) complex and its spread at the human-bird-environment interface, we isolated 11 strains of third-generation cephalosporin-resistant E. cloacae from 1003 specimens from 29 migratory bird species over two years in Chongming, Shanghai, China. The comprehensive analysis incorporated second- and third-generation sequencing techniques and extensive bioinformatic analysis. Four human-associated E. cloacae sequence types (STs), including ST432, ST412, ST1, and ST639, were found in migratory birds. We confirmed that the blaCMH-4 and blaCMH-6 genes were the major genotypes of the β-lactamase resistance genes in E. cloacae found in migratory birds. In addition, a thorough genomic analysis was performed on a global collection of 398 E. cloacae isolates carrying the blaCMH gene from 46 different countries. China had the highest proportion with 19.10 % (76/398), followed by Singapore with 18.34 % (73/398), Nigeria with 15.83 % (63/398), and the USA with 14.07 % (56/398). The first transmission of E. cloacae carrying blaCMH-4 and blaCMH-6 was defined around 1894 and 1549, respectively. Time-based phylogenetic analysis revealed that host jumps among humans, birds, and the environment led to the emergence of modern strains with ESBL- and carbapenem-resistant genes from about 2004 to 2016. The detection rate of insertion sequences (IS) of E. cloacae carrying blaCMH from human sources is higher than that from migratory bird sources, which is related to the different genetic environments caused by antibiotic selective pressure. It is crucial to have a comprehensive understanding of the characteristics exhibited by blaCMH producing E. cloacae in different ecological environments. Our results contribute to the effective monitoring and implementation of proactive strategies to reduce the spread of multidrug-resistant E. cloacae.

Circadian migrations of cave-dwelling crustaceans guided by their home chemical seascape

Organisms release and detect molecules for defense, reproduction, feeding strategies and finding suitable habitats. For some migratory species, homing behavior could be related to the recognition of their home chemical fingerprint made of an assemblage of molecules from their habitat. In the marine realm, the functioning of ecosystems such as underwater caves largely depends on trophic interactions between the caves and the outside environment. A key feature of these interactions relies on the circadian migration of small crustaceans (Mysida) from the cave habitat to the open sea. Recently, it has been hypothesized that these migrations could involve chemical mediation. Behavioral experiments using a two-choice system have shown that cave mysids significantly detect cave seawater rather than a control water from the open sea. Here, we used the same experimental system to investigate habitat recognition by two populations of the cave mysid Hemimysis margalefi. Both populations were submitted to a choice between three distinct cave seawaters vs. a control seawater. Additionally, experiments tested the water preference of a non-cave mysid species (Leptomysis sp.) between control and cave seawaters. To evaluate whether the choice of mysids was influenced by chemical cues from conspecifics, a complementary experiment on H. margalefi was conducted. Results demonstrated that each studied mysids population significantly recognizes the water of its own home habitat, and that this behavior is not influenced by the occurrence of H. margalefi’s exudates. Mass spectrometry-based metabolomic analyses revealed that each cave seawater had a specific chemical fingerprint with only a few reproducibly detected signals belonging to different chemical classes: peptides, alkaloids, fatty acids, steroids but also inorganic molecules. Organic pollutants have also been reproducibly detected. Among the detected compounds, one oxylipin derivative and one peptide could be considered as chemical markers of the cave ecosystem. Therefore, we postulate that the chemical seascape of each cave participates to mysid circadian migrations which are analogous to a daily-based homing behavior.

Synergic process of molybdenum recovery and ceramic preparation for clean and efficient utilization of industrial leaching residues

Ammonia-leaching residues of roasted molybdenite concentrates are intractable wastes and are mostly stockpiled in factories. Common treatments suffer from low Mo recovery and secondary pollution. This study has developed a synergistic process involving a single-step roasting with the addition of Al2O3 and MoO3 to recover Mo and simultaneously prepare porous refractories from the residues containing 5.6% Mo. The Mo separation efficiency, ceramic properties, and thermal behaviors—including chemical reactions, melting transformations, ceramic structure evolutions, and Mo species migrations—were comprehensively investigated. It was found that the addition of Al2O3 facilitated CaMoO4 decomposition to release volatile MoO3, thus promoting Mo recovery. The mullite started to form at about 900 °C, grew into whiskers, and further into interconnected clusters, under the catalytic effect of liquid MoO3 and the sintering effect of glassy melt. Liquid MoO3 was scattered on the outer surface of whisker clusters, achieving a high separation efficiency of over 98% after roasting at 1300 °C for 150 min. Meanwhile, a ceramic with a high porosity of 64.2% and a high compressive strength of 21.2 MPa was obtained, exhibiting promise for serving as a high-temperature insulation refractory. Overall, this study presents a novel approach for both the profound recovery of Mo and the value-added utilization of gangue minerals derived from CaMoO4-bearing wastes.