Restoring pollination services using forb-dense seed mixes is seen as a possible way to mitigate global pollinator decline. Research is needed on whether this management factor impacts other ecosystem services that could be influenced by greater emphasis on forbs than grasses in seed mixes. We tested grass:forb seeding ratios varying from 0:100 to 100:0 for their effects on multiple ecosystem services in a prairie restoration. We hypothesized that intermediate grass:forb seeding ratios, which have greater plant diversity, would result in greater supporting, regulating, and aesthetic services. We sowed 11 grass:forb seeding ratios and measured ecosystem service indicators (plant richness, plant productivity, animal-pollinated flower production, volunteer biomass, pollinator visitation, and butterfly visitation, an indicator of aesthetic services) over four growing seasons at a restoration in Iowa, USA. There were significant quadratic relationships between grass:forb seeding ratio and all of the above indicators except net primary productivity, which was not significantly related to grass:forb seeding ratio, suggesting no trade-offs among these ecosystem services at intermediate ratios. We further showed that greater service provision was related to increases of various seed mixture diversity indices. A structural equation model showed seed mix diversity has positive effects on invasion resistance and animal-pollinated flower production that indirectly enhance pollination and aesthetics. Volunteer biomass was suppressed with greater seed mix diversity. Overall, these results indicate that prairie restorations with intermediate grass:forb seeding ratios will have the optimal provision of ecosystem services, especially those that generate aesthetic appeal to people.
Global-scale peatland restoration holds large potential for carbon sequestration; however, the peatland carbon balance is not often considered alongside co-benefits in restoration prioritization. Here, we present a spatial optimization framework for inland peatland restoration to minimize greenhouse gas (GHG) emissions and maximize peatland co-benefits, such as flood mitigation and water quality improvements. We find strategic restoration of 30% of the world's drained inland peatlands, targeting areas with the greatest potential for GHG emissions reductions, would sequester three times more GHGs (0.91 ± 0.17 Pg CO2eq. year-1) than the same magnitude of peatland restoration implemented randomly (0.27 ± 0.11 Pg CO2eq. year-1). Peatland restoration is often driven by local needs for the many ecosystem services that peatlands provide; therefore, we also quantify the GHG balance of restoration aimed at delivering either water quality improvements or flood mitigation. Meeting a 30% global inland peatland restoration target while prioritizing water quality improvements or flood mitigation can still achieve emissions reductions of 0.34 ± 0.14 and 0.50 ± 0.19 Pg CO2eq. year-1 (62% and 44% less emissions reductions than prioritizing emissions alone), respectively, demonstrating opportunities for overlap between global GHG budgets and local environmental objectives. Finally, we use future methane (CH4) emissions projections to evaluate the compatibility of peatland restoration prioritization schemes with future CH4 emissions. We find that priority regions for near-term GHG emissions reduction do not necessarily align with areas that would minimize future peatland CH4 emissions, due to increasing CH4 emissions by 2100. We account for uncertainty and variability in long-term emission trajectories of peatland restoration from diverse settings, site histories, and practices by testing our optimization framework with two alternate endpoint scenarios: "recently rewetted" and "restored to intact conditions." Our framework highlights numerous opportunities for inland peatland restoration to simultaneously achieve both near- and long-term emission reductions as well as multiple co-benefits. Broad-scale restoration strategies can be employed in concert with planning for regional needs and site-specific criteria to magnify the benefits of peatland restoration.
Understanding the population dynamics of migratory species requires consideration of their entire annual cycle. A key requirement is the decomposition of annual survival into seasonal periods. While there is increasing evidence that migrations are the most dangerous phase of the annual cycle, temporal variation in seasonal survival and its effect on population dynamics is still poorly understood. Estimating seasonal survival is challenging when individuals are only encountered during a restricted period of their annual cycle. We developed and tested a continuous-time capture-recapture model applicable to data from marked individuals that can only be encountered during the breeding season. This model allows annual survival to be separated into breeding and non-breeding periods. We applied this model to encounter data of hoopoes (Upupa epops) collected between 2002 and 2024 from a Swiss population during the breeding period to estimate survival during the breeding and the non-breeding periods and their respective annual variations. We then linked seasonal survival with environmental variables from the breeding, stopover, and wintering grounds, which have been documented by previous research on the same population. Mortality hazards were 17 times greater during the non-breeding than during the breeding period, with stronger annual variation observed in the former. Mortality increased during both seasonal periods when a surrogate of prey abundance at the wintering grounds was lower. The effect during the non-breeding period highlighted that environmental conditions outside the breeding season were an important driver of hoopoe population dynamics, whereas the effect during the breeding period was weaker and provided evidence of a carry-over effect. In contrast, the environmental variables considered on the breeding and stopover grounds had little impact on seasonal survival. The study adds to the growing body of evidence suggesting that migration and wintering are critical phases in the life cycle of migratory birds and that population dynamics are strongly affected by environmental conditions encountered during wintering. The methodological approach developed is applicable to datasets that record multiple encounters of individuals during the breeding season. It enables the analysis of existing data to study temporal variation in survival across periods of the annual cycle.
Habitat restoration is increasing globally, aiming to recover biodiversity and ecosystem services. To assess the success and value of such restoration projects, we need to understand how and when they produce desired restoration outcomes. However, there is currently limited data-driven understanding of how biodiversity and ecosystem services develop over extended timescales (e.g., decades) following restoration. While ecosystem services can be challenging to quantify, functional traits can be used as effective proxies that are more easily measured. Here, we employed a space-for-time approach at multiple restored sites (6-33 years old) in two estuaries in eastern Australia (Hunter River estuary and Maroochy River estuary) to explore temporal trajectories of functional traits in coastal wetlands. We found diverse, often nonlinear temporal trends for numerous functional traits in mangrove and saltmarsh habitats, including saltmarsh cover, saltmarsh burrows, mangrove height, and mangrove saplings, all of which directly link to ecosystem services. Further understanding of ecosystem service changes after restoration can inform ongoing monitoring and management, which may improve predictions of recovery timescales. These will help refine restoration goals and manage project expectations, thereby increasing future restoration success.
Anthropogenic disturbances and environmental change have resulted in the loss of migratory behaviors, an important life history strategy of many species. Identifying the mechanisms and ecological benefits of migratory behavior is important for conservation and management decision-making. We evaluated the putative mechanisms influencing partial migration in moose (Alces americanus) populations occupying landscapes characterized by anthropogenic and natural disturbances. We quantified differences in the ecology of moose that migrated or stayed resident on their winter range. Also, we assessed three possible effects of the choice to migrate: occurrence of parturition, adult survival, and cause of adult death. Wildfire disturbance in the winter range had the strongest influence on whether an individual migrated and most migratory moose experienced less wildfire disturbance in their summer range than their winter range. However, not all migrants were successful at reducing the amount of wildfire disturbance they experienced in their summer range. Moose were more likely to give birth if they migrated a relatively long distance in the spring of the previous year. Movement strategies did not affect the probability of adult survival, but they were associated with the causes of adult mortality. Residents were more likely to die of health-related causes while migrants were more likely to die from predation. Increased wildfire severity in the summer range, associated with warmer and drier climates, could alter migratory behaviors and the benefits of migration for moose.
Environmental DNA (eDNA) concentration varies through space and time, and measurements collected close together are often correlated. Ignoring this dependence can inflate the rate of incorrect ecological inferences (Type I error rate). Although spatial correlation in eDNA has received considerable attention, temporal correlation has been less well studied. Statistical models and study designs that account for temporal correlation are increasingly important to understand time-dependent effects in complex systems. We developed a hierarchical model that separates temporal ecological variation from variability stemming from sampling and laboratory processes and applied it to four single-site eDNA time series collected over 17-24 days, three of which provided sufficient information for parameter estimation. We then used the empirically estimated parameter magnitudes in a simulation study to evaluate alternative temporal sampling designs that considered (1) how a fixed number of samples are allocated across different numbers of sampling times with different levels of temporal replication and (2) equally spaced versus cluster-spaced sampling (short bursts separated by longer gaps). Across the three time series sufficient for analysis, we observed substantial sampling variability, temporal variability, and temporal correlation, although correlation was estimated imprecisely (large coefficient of variation). Simulations showed that when sampling intervals were shorter than the effective temporal correlation range, models that ignored temporal dependence produced inflated Type I error rates and frequently detected spurious temporal trends. Accounting for temporal correlation substantially reduced this inflated Type I error rate. Optimal sampling strategies depended on study objectives. Clustered sampling most effectively estimated temporal correlation. When temporal dependence was negligible, evenly spaced sampling maximized power to detect trends. Estimating sampling variability required concentrating effort into fewer sampling times with more replicates per time, whereas estimating temporal variance was most precise with intermediate levels of replication. Together, these results indicate that temporal dependence can strongly affect inference from quantitative eDNA time series when sampling intervals approach the correlation timescale. Designs that ignore this dependence risk inferring ecological change or difference where none exists. Our framework provides practical guidance for allocating sampling effort in temporally intensive eDNA monitoring and for interpreting trends from short time series.
Bottom trawl fisheries are recognized to be a global threat to marine biodiversity and a dominant driver of sea floor ecosystem change. Although the mechanism of trawling impact on benthic life is more and more documented and empirically verified, there is still no standard toolbox that enables the prediction of impact in any area and that is soundly based on existing knowledge. We provide an R package ("Bfiat") endowed with functionalities that enable researchers as well as managers to assess the vulnerability of benthic organisms and associated ecosystem functions to trawling. The Bfiat package includes a deterministic modeling framework that predicts the state of benthic species following trawling disturbance as a fraction of pre-disturbance state. Benthic state is predicted according to the logistic population growth model combined with trawling parameters and organism functional traits. While trawling parameters determine the disturbance, functional traits express vulnerability through instantaneous sensitivity and longer term recoverability in the model response. We illustrate the potential of the package through a large-scale case study with species communities of contrasting functional compositions. Benthic response to trawling disturbance is exemplified from single species to entire community as well as from single station to larger spatial extent.
Anthropogenic landscapes generally provide abundant human foods but increase mortality risk, which can alter vital rates for some species. Some species exhibit altered survival in anthropogenic landscapes, whereas others exhibit changes in reproduction. While changes in vital rates have been previously documented, the role of human food subsidies in vital rate trade-offs is often overlooked, especially for large carnivores. Here, we explored how human food subsidies affect American black bear (Ursus americanus, Makwa [Ojibwe]) apparent survival, recruitment, and population growth rate. We compared bears in a protected island ecosystem featuring minimal risk of human-caused mortality and little human food to a neighboring mainland population featuring relatively high human-induced mortality from hunting but abundant human food subsidies. We estimated proportional diets of 105 bears using stable isotope analysis (δ13C and δ15N), assessed how landcover types in bear use areas influence diet, and explored how these variables affected bear vital rates. Island bears consumed almost entirely natural foods, principally hard mast, with virtually no human foods. Mainland bears consumed a diversity of items with nearly 1/3rd of their diet coming from human foods. Bear survival on protected islands increased with the amount of hard mast consumed, while survival on the mainland was not correlated with either diet or landcover. These populations also exhibited notable differences in vital rates: bears on the islands were characterized by high survival (>0.8 annual survival) but low recruitment (<0.2 annual recruitment), whereas bears on the mainland exhibited 37% lower survival (0.44 annual survival) but 35% (0.54 annual recruitment) higher recruitment. Our work suggests that anthropogenic landscapes, and notably food subsidies they provide, can lead to a trade-off in vital rates by changing the risk-reward landscape. Conversely, refugia that maintain natural trophic pathways can maintain intact food webs and ecosystem processes.
Agroforestry practices managed by indigenous communities have been identified as viable alternatives to monoculture practices in the transition from shifting cultivation to sedentary agricultural systems. Nonetheless, the long-term effects of such transitions on the dynamics of soil organic carbon (SOC) are not fully understood. In this study, we predict changes in SOC stock across a chronosequence of a natural forest stand and pineapple agroforestry systems (PAFSs) using an ensemble of models with four shared socioeconomic pathway scenarios. There was a strong agreement between the simulated and observed SOC stocks. Simulated SOC stocks with the Rothamsted Carbon (RothC) model in 15-year-old PAFS (83.2 Mg C ha-1) did not significantly differ from the value (90.4 Mg C ha-1) simulated for the natural forest. Simulations further revealed that average SOC stocks in 15-year-old PAFS would increase by 1.6 Mg C ha-1, while SOC stocks would decrease by 5.4 Mg C ha-1 in natural forests under climate change scenarios by 2060. It is concluded that traditional agroforestry practices such as PAFS can restore degraded land under shifting cultivation in the mountainous regions of the Indian East Himalayas and contribute to achieving carbon neutrality.
Invasive species are a threat to ecological and anthropogenic systems. In the United States, policies to coordinate funding and precipitate management action have been slow to emerge at the federal level, and there is a patchwork of regulation and legislation at the state level. This means that managers and policymakers, already facing limited budgets and evolving goals for action on invasive species, also face detrimental policy inconsistencies across states. Although previous research has explored state-level invasive plant policy, policy relating to invasive invertebrate and vertebrate taxa (and across all three) is understudied. We expand upon previous taxa-limited examinations of public policy related to invasives, looking across all taxonomic groups, including plants, to explore coherency of state regulations. We expanded the taxonomicscope of a database of policies in 21 contiguous eastern US states and used it to examine (in)consistencies in spatial trends for invasive species listed in policies across and within taxonomic groups. We examined the coherency of neighboring states and regional overlap of named species. We also analyzed correlations between distances among states and the species listed in the policy to examine regional trends. We found 1117 policy segments relevant to invasive species with 448 naming at least one taxon at the genus or species level. Of these, 35.3% were plants, 19.9% were invertebrates, and 44.8% were vertebrates. The distribution of taxa contained within policies varied across states, underscoring high variability in the proportion of taxa listed in the policies of neighboring states. Even lower policy coherency existed at the regional scale, particularly for invertebrate and vertebrate taxa. Our results indicate that policy inconsistency exists across all taxonomic groups, and the lack of attention to invasive invertebrates and vertebrates across state policies is particularly concerning. Policy inconsistency means that proactive states are susceptible to invasion from neighboring states where invasives are not similarly regulated. There is an opportunity to improve coordination between states to reduce vulnerability to invasives due to policy inconsistency.
Understanding livestock-wildlife interactions, especially in forest ecosystems, is critical for biodiversity conservation and sustainable land management. However, the long-term and cascading impacts of livestock grazing on forest structure and community bioacoustics are important yet largely neglected areas of research. Here, we used acoustic indices and a sound event detection (SED) model to evaluate the effects of continuous cattle grazing on seasonal soundscapes in Northeast China. We collected and analyzed over 18,785 h of recordings from 10 cattle-grazed forest plots and 10 ungrazed forest plots in Northeast China. We identified sound events in each recording via deep learning and calculated six acoustic indices, as well as extracted vegetation characteristics using light detection and ranging point cloud data. Our results revealed that grazing activities significantly changed seasonal soundscape dynamics, with biophony being highest in grazed forests and lowest in ungrazed forests in winter. Livestock shifted the forest soundscape composition by increasing the audibility of birds and insects while decreasing the vocalizations of sika deer (Cervus nippon) and crows, resulting in reduced sound diversity and complexity in grazed forests. We also found that grazing can reduce the leaf area index, herbaceous plants, and canopy density, which can influence these effects indirectly. Interestingly, cowbells noticeably altered the dawn chorus of birds; during spring and summer grazing periods, the chorus was characterized by an increased bird calling rate and greater vocal complexity (elevated Acoustic Complexity Index), patterns consistent with a behavioral adjustment to acoustic masking. This study highlights how livestock modify forest acoustic communities. To preserve natural soundscapes, we suggest mitigating cowbell noise through silent trackers (e.g., GPS) or reduced bell density in priority zones. Sustainable practices, including rotational grazing and buffer zones, are also vital to maintain forest structure and acoustic diversity. We suggest that integrating SED models with acoustic indices provides a robust framework for monitoring such anthropogenic disturbances.
Degradation in drylands is widespread, yet our ability to restore dryland native plant communities is nearly nonexistent. Recruitment from seed is often <10%, due to many factors including harsh conditions that lead to seed dormancy and seedling mortality and high levels of competition with invasive species. Degradation exacerbates these challenges by decreasing topography, water-holding capacity in soil, and perennial vegetation which can act as microsites for seed regeneration. In this experiment, we tested soil pits, biochar soil amendments, and seed pellets as three strategies to create seed microsites and ameliorate harsh conditions in a degraded landscape. We measured seedling density and biomass of both native and non-native species after one growing season. We also assessed impacts of the treatments on soil microbial communities. Seeding alone, with or without a seed pellet, did not result in seedlings in the absence of other treatments. Microsite creation increased native plant density by about 10-fold, and biomass by about 100-fold, compared to controls. Native plant biomass was even higher-about 300-fold greater than controls-with the addition of biochar to the microsites. Non-native seedling density and biomass was also highest, by about 10-fold and 6-10-fold, in pits and pits with biochar, respectively. Soil moisture was significantly higher in microsites, likely driving these native and non-native vegetation trends. There was no effect of seed pellets on plant density or biomass, and in most cases, pellets performed slightly worse than broadcast bare seeds. Bacterial communities in reference soils did not differ from those in degraded areas, but there were differences in response to the microsite treatments. Our results support our hypothesis that microsite limitation, coupled with seed limitation, poses a barrier to seeded restoration in highly degraded semiarid grasslands. Addressing this barrier could improve stubbornly low plant recruitment rates in dryland restoration, making projects more effective.
Roads are vital for human societies, yet they can also have negative impacts on the ecological communities that live in close proximity to them. Insect pollinators, which nest and forage in road verges running alongside roads, are a group of particular importance. These verges may act as an "ecological trap," drawing insect pollinators into contact with traffic, increasing the risk of pollinator-traffic collisions. Spanning six European regions, we evaluated the complex relationships between traffic, road verge floral composition, and surrounding land use to understand how these factors influence abundance and richness of bees, butterflies, and hoverflies sampled within road verges. Across the study, we observed 10,960 pollinators belonging to 293 species of bees, butterflies, and hoverflies. We observed greater pollinator abundance in verges with higher flower cover, and greater pollinator richness in verges with more species of flowering plants. Lower abundances of bees and butterflies and lower species richness of bees were observed when traffic speed in the adjacent road was higher. This study indicates that road verges with abundant and diverse floral resources support more abundant and diverse pollinator populations, especially on verges alongside lower speed roads. We recommend that lower speed roads should be prioritized for floral enhancements.
Organism movement is a key process in the transfer of individuals, genes, functional traits, matter, and energy among habitat patches, at sea and across the land-sea interface. The resulting fluxes, collectively termed marine functional connectivity (MFC), underpin planetary health and an array of ecosystem services. The ecological and economic impacts of rapid environmental change, including climate change, overexploitation, habitat loss and fragmentation, and the global transport of nonindigenous species make accurate estimation and prediction of MFC patterns paramount. However, estimating MFC is challenging given the relative inaccessibility of the oceans and the small size of many of the organisms and life stages with the highest dispersal potential. Here, we provide a methodological roadmap to help researchers and stakeholders understand, use, and integrate different tools to estimate organism movement and connectivity, focusing on (1) tagging and telemetry, (2) analysis of chemical markers in body tissues and structures, (3) genetics, and (4) numerical modeling. We describe method strengths and weaknesses, and the spatiotemporal resolution and scale of resulting connectivity estimates. Ancillary and emerging methods to estimate MFC are also reviewed. We then present case studies that have successfully applied or integrated different methods, particularly to support (1) marine protected area design, (2) global change predictions, focusing on climate change and bioinvasions, and (3) fisheries management. Finally, we highlight methodological innovations and concepts that promise to transform MFC research in the future.
Biological invasions often generate complex ecological paradoxes, particularly when invasive species act as ecosystem engineers that simultaneously compete with and benefit native communities. Understanding these dual dynamics is critical for managing urban biodiversity. Here, we investigated the interactions between invasive monk parakeets (Myiopsitta monachus) and native avifauna to assess the balance between behavioral competition and structural commensalism. We assessed competition through (1) agonistic interactions and (2) correlations between parakeet abundance and that of native species. Commensalism was evaluated by analyzing tenant species in parakeet nests and the drivers of their occurrence. Agonistic interactions manifested through highly species-specific conflicts: Density-dependent aggression with rock pigeons (Columba livia) was strictly reciprocal, while parakeets directed targeted intimidation toward Eurasian magpies (Pica pica). Conversely, direct agonistic encounters involving either Eurasian tree sparrows (Passer montanus) or house sparrows (Passer domesticus) were negligible. However, spatially, Passer spp. abundance correlated negatively with the number of parakeet nest chambers (a proxy for parakeet abundance), whereas common blackbirds (Turdus merula) showed a positive correlation. Furthermore, parakeets provided a massive structural subsidy. We recorded 11 native species breeding in 48% of surveyed parakeet nests (N = 252). Tree sparrows and stock doves (Columba oenas) dominated this tenant community, accounting for 86% of native breeding pairs. Native breeding abundance-including tree sparrows, stock doves, and rock pigeons-as well as total species richness scaled positively with nest chamber density. Yet, active parakeet presence limited nest use for stock doves but did not deter tree sparrows or rock pigeons from successful co-nesting. Our findings reveal a dual ecological dynamic: Parakeets show a negative spatial correlation with declining urban sparrows, yet simultaneously act as ecosystem engineers by providing valuable breeding habitats for local biodiversity. However, without data on tenant reproductive success and pathogen transmission, these novel subsidies risk functioning as ecological traps. Consequently, while indiscriminate nest removal could inadvertently harm native tenants, current evidence does not confirm the long-term safety of this commensalism. Effective management must transcend simple eradication, adopting a holistic framework that weighs the loss of nesting resources against the competitive and sanitary risks of retaining these invasive populations.
Widespread anthropogenic landscape change, particularly from energy development, has fundamentally reshaped ecosystems, and understanding species responses remains a central ecological challenge. Remote camera traps are widely used to estimate mammal abundance and distribution, but inferring species-habitat relationships from these data is complicated by the spatial scale at which landscape features are measured. We apply foundational concepts of landscape ecology to explore whether predictable patterns in scale emerge within a broad mammal community inhabiting a highly developed landscape. Using camera trap data from 11 mammal species and a multi-scale, information-theoretic modeling approach, we investigated: (1) how best-supported spatial scales differ between anthropogenic and natural features; (2) species-scale patterns when modeling similar landscape attributes separately versus together; and (3) evidence for patterns of species-scale relationships based on body size and trophic level. We found that best-supported spatial scales spanned the entire range of sizes considered, from 250 to 5000 m. Best-supported scales differed between anthropogenic disturbances and natural landcover model sets for most species, but without a predictable direction. Similarly, optimal scales varied across species but showed no consistent relationship with species traits such as body size or trophic level. Species' best-supported spatial scales did not converge on a characteristic scale more frequently when similar landscape attributes were considered in individual models versus combined into a global model, nor did scale domains emerge consistently for global models. Our findings emphasize the complex and context-dependent nature of species-landscape interactions and underscore the importance of evaluating spatial scale in ecological analyses. Explicit consideration of scale, including evaluating a broad range of spatial extents, and, where appropriate, implementing multi-scale approaches can improve ecological inference and interpretation. Transparent reporting of scale decisions and critical evaluation of how scale influences results are essential for robust assessments of species responses to landscape change.
The marine aquarium trade (MAT) is a significant global industry harvesting millions of wild-caught, live coral reef fishes for public and private aquaria markets in the United States and Europe annually, while supporting fisher livelihoods in the Indo-Pacific. This diverse and species-rich trade is considered data-limited, creating barriers to quantifying the current and future socio-ecological sustainability of the fishery. We present a revised and expanded productivity-susceptibility analysis (PSA) that serves as a holistic risk assessment to estimate the vulnerability of marine aquarium fish to overfishing. Our global analysis includes 306 species that are actively in trade. Improvements to the PSA framework from previous research including novel susceptibility factors, methods to overcome missing data for individual species factors, and assessing a large, diverse group of marine fish under a single, targeted assessment framework. Our results show that an overwhelming 81.4% of species evaluated fall into the least or moderately vulnerable classification, while the remaining species (n = 57) have higher vulnerability scores designating them as high priority for localized assessment and management initiatives. Most teleost fish in the trade are considered sustainable, while eels and elasmobranchs have the highest vulnerability scores. A comparative case study between our PSA and the popular FishBase vulnerability tool illustrates how the latter can be ill-suited to handle the data limitations common to nonfood fishes. Our study demonstrates how the PSA is a robust, data-limited fishery assessment to prioritize species in the MAT for further assessment, monitoring, and management.
Habitat patch dynamics can scale up to influence population demography and diversity with implications for resilience to environmental stochasticity. But how the spatial arrangement and size of habitat patches interact with other components of habitat heterogeneity to shape population diversity at larger spatial scales is not well understood. For riverine fishes, there is increasing evidence that tributary streams provide critical demographic support to main stem rivers. However, the extent to which main stem rivers rely on demographic contributions from tributaries, and the factors underlying this dependence, have not been assessed. Here, we used genetic stock identification to evaluate the effect of tributaries on population diversity of Yellowstone cutthroat trout (Oncorhynchus virginalis bouvieri) occupying the main stem Snake River, Wyoming, USA. We found that the main stem relied almost entirely on tributaries for demographic support, but main stem composition varied spatially among river sections. Distance between habitat patches, catchment area, and groundwater availability acted in concert to determine the contribution of specific tributaries to the main stem, but contributions were ultimately modulated by habitat connectivity. We also found evidence for multi-scale spatial structure in tributary contributions, providing insight into untested drivers of main stem river population diversity. Our results demonstrate how spatially discrete and distributed riverscape attributes influence population diversity at broader spatial scales, illustrating how ecosystem resilience emerges from the dynamic, two-way exchange of individuals and energy across habitat networks. Management plans for large rivers that address the ecological contributions of tributaries may be needed to achieve optimal outcomes. Similarly, conservation strategies that exclusively focus on headwater streams may fail to capture the broader habitat requirements necessary to maintain robust cold-water fish populations and associated recreational fisheries, particularly under global environmental change.
Long-term monitoring programs are crucial to assess trends in biodiversity and so make informed decisions for conservation and resource management. However, disregarding the statistical power of a monitoring program can lead to incorrect conclusions about species population trends, potentially resulting in ineffective management and misdirected resource allocation. In Australia, predation by introduced red foxes (Vulpes vulpes) and feral cats (Felis catus) remains a major cause of native faunal decline and extinction. Australia spends more than $16 million yearly in controlling foxes for biodiversity conservation, primarily through landscape-scale poison baiting. Using a long-term fox baiting and threatened species monitoring program in southeastern Australia, we collated data from 2132 camera-trap deployments to: (1) explore drivers of the distribution of threatened native mammals and introduced predators, (2) conduct a spatially explicit power analysis to assess the program's ability to detect trends in native and introduced species occupancy for the next 10 years, and (3) provide recommendations for improving monitoring efforts through alternative scenarios. We found that threatened native mammals were more likely to occupy areas with high densities of fox baits, whereas foxes were less likely to occupy these areas; however, these areas were quite localized within baited regions. The power of the existing monitoring design was sensitive to the magnitude of change in occupancy, but robust to approximately 15% changes in the number of survey sites. The monitoring program showed adequate power (>0.8) to detect its original aims: increases in threatened native mammal occupancy and decreases in fox occupancy in baited areas. Hence, the lack of a strong signal of increasing native mammal occupancy in the last 8 years likely indicates that the system has reached a stable state under current management, rather than poor statistical power. This may potentially be the case in many long-term predator management programs. If removing some sites from an existing monitoring design does not considerably vary power, managers could consider diverting these resources to, for example, improving understanding of species-habitat relationships or intensifying predator management efforts.
Ecosystem dynamics can lead to trade-offs between reaching harvest targets and protecting vulnerable species across fisheries management decisions. However, in the context of rebuilding overfished populations, considering predator-prey interactions might provide opportunities to minimize or reverse these trade-offs if overfished prey can recover when predators in shared habitat are harvested. To understand whether and under what conditions such opportunities might arise, we explore the effect of predator harvest on the rebuilding outcomes of a recovering prey that experiences bycatch mortality. We developed an age-structured model with predation and harvest to evaluate changes in the population dynamics of prey at steady state and in their rebuilding time under increasing harvest of predators. We parameterized our models based on yelloweye rockfish (Sebastes ruberrimus), a U.S. West Coast Groundfish stock under a rebuilding plan, and one of their known predators, lingcod (Ophiodon elongatus). We found that lingcod harvest reduced the long-term spawning biomass and increased the rebuilding time of yelloweye rockfish regardless of their prey specialization; these negative effects were due to yelloweye rockfish bycatch in the lingcod fishery. However, the degree to which predator harvest affects prey rebuilding depends on prey specialization, where the steady-state dynamics of yelloweye rockfish were less affected by lingcod harvest and rebuilding occurred more rapidly when lingcod acted as a specialist compared to a generalist predator. As efforts to leverage ecosystem attributes in fisheries management are applied to recovery strategies, we highlight the role that the nature and strength of biological interactions can play in shaping outcomes of recovery.
