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1. Applicability of 3D Spectral Element Method for Computing Close-Range Underwater Piling Noises

   https://doi.org/10.1142/S2591728519500129  

   Jeong, C. ; Manalaysay, A. ; Gharti, H. N. ; Guan, S. ; Vignola, J. ( December 2019 , Journal of Theoretical and Computational Acoustics)

   null (Ed.)

   Pile driving is used for constructing foundation supports for offshore structures. Underwater noise, induced by in-water pile driving, could adversely impact marine life near the piling location. Many studies have computed this noise in close ranges by using semi-analytical models and Finite Element Method (FEM) models. This work presents a Spectral Element Method (SEM) wave simulator as an alternative simulation tool to obtain close-range underwater piling noise in complex, fully three-dimensional, axially-asymmetric settings in the time domain for impacting force signals with high-frequency contents (e.g., frequencies greater than 1000[Formula: see text]Hz). The presented numerical results show that the flexibility of SEM can accommodate the axially-asymmetric geometry of a model, its heterogeneity, and fluid-solid coupling. We showed that there are multiple Mach Cones of different angles in fluid and sediment caused by the difference in wave speeds in fluid, a pile, and sediment. The angles of Mach Cones in our numerical results match those that are theoretically evaluated. A previous work 18 had shown that Mach Cone waves lead to intense amplitudes of underwater piling noise via a FEM simulation in an axis-symmetric setting. Since it modeled sediment as fluid with a larger wave speed than that of water, we examined if our SEM simulation, using solid sediment–fluid coupling, leads to additional Mach Cones. Because this work computes the shear wave in sediment and the downward-propagating shear wave in a pile, we present six Mach Cones in fluid and sediment induced by downward-propagating P- and S-waves in a pile in lieu of two previously-reported Mach Cones in fluid and sediment (modeled as fluid) induced by a downward-propagating P-wave in a pile. We also showed that the amplitudes of the close-range underwater noise are dependent on the cross-sectional geometry of a pile. In addition, when a pile is surrounded by a solid of an axially-asymmetric geometry, waves are reflected from the surface of the surrounding solid back to the fluid so that constructive and destructive interferences of waves take place in the fluid and affect the amplitude of the underwater piling noise. 

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2. Behavioural responses to warming differentially impact survival in introduced and native dung beetles

   https://doi.org/10.1111/1365-2656.13366  

   Mamantov, Margaret A. ; Sheldon, Kimberly S. ; Behmer, ed., Spencer ( October 2020 , Journal of Animal Ecology)

   Anthropogenic changes are often studied in isolation but may interact to affect biodiversity. For example, climate change could exacerbate the impacts of biological invasions if climate change differentially affects invasive and native species. Behavioural plasticity may mitigate some of the impacts of climate change, but species vary in their degree of behavioural plasticity. In particular, invasive species may have greater behavioural plasticity than native species since plasticity helps invasive species establish and spread in new environments. This plasticity could make invasives better able to cope with climate change.

   Here our goal was to examine whether reproductive behaviours and behavioural plasticity vary between an introduced and a nativeOnthophagusdung beetle species in response to warming temperatures and how differences in behaviour influence offspring survival.

   Using a repeated measures design, we exposed small colonies of introducedO. taurusand nativeO. hecateto three temperature treatments, including a control, low warming and high warming treatment, and then measured reproductive behaviours, including the number, size and burial depth of brood balls. We reared offspring in their brood balls in developmental temperatures that matched those of the brood ball burial depth to quantify survival.

   We found that the introducedO. taurusproduced more brood balls and larger brood balls, and buried brood balls deeper than the nativeO. hecatein all treatments. However, the two species did not vary in the degree of behavioural plasticity in response to warming. Differences in reproductive behaviours did affect survival such that warming temperatures had a greater effect on survival of offspring of nativeO. hecatecompared to introducedO. taurus.

   Overall, our results suggest that differences in behaviour between native and introduced species are one mechanism through which climate change may exacerbate negative impacts of biological invasions.

    

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3. Bioacoustic monitoring reveals shifts in breeding songbird populations and singing behaviour with selective logging in tropical forests

   https://doi.org/10.1111/1365-2664.13492  

   Pillay, Rajeev ; Fletcher, Jr, Robert J. ; Sieving, Kathryn E. ; Udell, Bradley J. ; Bernard, Henry ; Paiva, ed., Vitor ( September 2019 , Journal of Applied Ecology)

   Selective logging is the primary cause of tropical forest degradation and is rapidly expanding worldwide. While the impacts of logging on species diversity and distributions are well understood, little is known about the effects of logging on animal behaviours central to individual fitness and population persistence.

   The song rate of breeding songbirds is a behavioural trait that is often positively associated with male density and used by conspecific females as an indicator of territory and male quality. Thus, contrasting logging‐induced adjustments in song rates of individual birds with population shifts may illuminate potential mechanisms underlying population distributions.

   We present a novel application of bioacoustic monitoring, integrating counts of individuals, songs and duets from single automated recording units (ARUs) withN‐mixture models, to estimate shifts in population parameters (occupancy, abundance) and singing behaviours (per‐capita song rates, per‐pair duet rates) of 32 Bornean songbird species with logging. We tested hypotheses on the relationships between adjustments in behavioural and population parameters with logging, and further tested the extent to which species traits predicted behavioural and population shifts.

   Adjustments to singing behaviour in 59 and 53% of species (57% of duetting species) were concordant with differences in occupancy and abundance respectively, such that species showing reduced populations with logging also produced fewer songs per‐capita, and vice versa. Species known to prefer undisturbed habitats and large‐bodied species showed the most negative effects of logging on singing behaviour and population distributions. Species known to exploit degraded habitats exhibited the opposite pattern. Subdued singing in logged forests by species of conservation concern suggests limited competition between territorial males in small populations and may also signal low‐quality territories.

   Synthesis and applications. We demonstrate that bioacoustic monitoring can be used to not only estimate important population parameters of occupancy and abundance across a diverse tropical songbird community, but also enables quantification of behaviours considered relevant to individual fitness, yet unobtainable with conventional methods (e.g. point counts). Bioacoustics provides a viable approach to reliable automated large‐scale monitoring of hyperdiverse tropical forest systems under logging operations and other land‐use pressures.

    

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4. Quantifying cryptic function loss during community disassembly

   https://doi.org/10.1111/1365-2664.13507  

   Terui, Akira ; Finlay, Jacques C. ; Hansen, Amy T. ; Kozarek, Jessica L. ; Januchowski‐Hartley, ed., Stephanie ( October 2019 , Journal of Applied Ecology)

   Emerging theory suggests that the ecosystem‐level consequences of anthropogenic pressures depend on how species will be disassembled from ecological communities (i.e. the disassembly rule). Species loss, however, is not the sole ecological cause of ecosystem function loss: behaviours underpinning ecosystem function can also be disrupted by anthropogenic pressures without detectable declines of component species (‘cryptic function loss’).

   Here, we introduce a novel framework that integrates behavioural responses into community disassembly metrics. We applied this framework to freshwater mussel communities (order Unionida) of the midwestern United States, in which intensive agricultural land use threatens stream biota. We combined a field experiment, meta‐analysis and watershed‐scale population dataset to assess how excessive sediment concentrations, one of the leading drivers of freshwater biodiversity loss, influence community‐level water clearance rates of freshwater mussels via behavioural (changes in mass‐specific clearance rate) and population (changes in population density) responses.

   Our study provided three key insights. First, freshwater mussels exhibited high behavioural sensitivity to increased total suspended solids (TSS) across species (i.e. reduced water clearance rate), whereas population responses were highly species‐specific. Second, the behavioural response to increased TSS causes substantial cryptic function loss under stressful conditions: simulated water clearance rates when behavioural response is included can be less than half that of mussel communities with no behavioural response. Finally, simulations revealed that mussel communities are likely to show rapid but consistent rates of ecosystem function loss irrespective of disassembly rules. The similar rates of function loss are due to the uniform behavioural response to TSS that masks the linkage between population sensitivity of a species and its contribution to ecosystem function.

   Synthesis and applications. Our findings suggest that ignoring behavioural processes may cause non‐negligible underestimation of ecosystem function loss during community disassembly, potentially leading to overly optimistic assessments of ecosystem resilience. Furthermore, unlike species declines or local extinctions, behaviour response tied to function loss may occur concurrently with increasing anthropogenic pressures. Therefore, managers should acknowledge the risk of immediate function loss after human‐induced environmental changes.

    

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5. Neurogenomic landscape associated with status‐dependent cooperative behaviour

   https://doi.org/10.1111/mec.17327  

   Bolton, Peri E. ; Ryder, T. Brandt ; Dakin, Roslyn ; Houtz, Jennifer L. ; Moore, Ignacio T. ; Balakrishnan, Christopher N. ; Horton, Brent M. ( March 2024 , Molecular Ecology)

   The neurogenomic mechanisms mediating male–male reproductive cooperative behaviours remain unknown. We leveraged extensive transcriptomic and behavioural data on a neotropical bird species (Pipra filicauda) that performs cooperative courtship displays to understand these mechanisms. In this species, the cooperative display is modulated by testosterone, which promotes cooperation in non‐territorial birds, but suppresses cooperation in territory holders. We sought to understand the neurogenomic underpinnings of three related traits: social status, cooperative display behaviour and testosterone phenotype. To do this, we profiled gene expression in 10 brain nuclei spanning the social decision‐making network (SDMN), and two key endocrine tissues that regulate social behaviour. We associated gene expression with each bird's behavioural and endocrine profile derived from 3 years of repeated measures taken from free‐living birds in the Ecuadorian Amazon. We found distinct landscapes of constitutive gene expression were associated with social status, testosterone phenotype and cooperation, reflecting the modular organization and engagement of neuroendocrine tissues. Sex‐steroid and neuropeptide signalling appeared to be important in mediating status‐specific relationships between testosterone and cooperation, suggesting shared regulatory mechanisms with male aggressive and sexual behaviours. We also identified differentially regulated genes involved in cellular activity and synaptic potentiation, suggesting multiple mechanisms underpin these genomic states. Finally, we identified SDMN‐wide gene expression differences between territorial and floater males that could form the basis of ‘status‐specific’ neurophysiological phenotypes, potentially mediated by testosterone and growth hormone. Overall, our findings provide new, systems‐level insights into the mechanisms of cooperative behaviour and suggest that differences in neurogenomic state are the basis for individual differences in social behaviour.

    

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