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Coastal and marine ecosystems provide valuable ecosystem services and functions. Unfortunately, these habitats have experienced increasing anthropogenic and climate‐related pressures, leading to significant degradation and loss not only in Australia but also globally. Hence, the urgency for coastal and marine ecosystem restoration has never been more pronounced. We present a synthesis of 151 projects on coastal and marine restoration in Australia spanning mangrove, seagrass, tidal marsh, kelp, shellfish reef, and coral ecosystems. Our findings reveal increased restoration efforts over the past 30 years, with an increased focus on coral and shellfish reef habitats. Across Australia, most efforts were in southeastern Australia, with a noticeable gap in the Northern Territory. Restoration strategies focused on enhancing propagule availability (74%) and substrate availability (42%), with additional efforts toward implementing top–down (7%) and bottom–up (4%) controls to boost natural recruitment. Projects were carried out with the participation mostly of research universities (45%), followed by state government entities (42%), philanthropy (34%), and private companies (16%). Funding came primarily from governmental sources, such as state government entities (50%), the commonwealth (44%), and philanthropy (19%). Restoration outcomes are centered on monitoring growth and survival resulting from both single and multiple restoration actions. Our findings highlight key factors influencing natural recruitment across habitat types, where sedimentation and species reproductive biology play a critical role. While acknowledging that our results represent only a small fraction of Australia's coastal and marine restoration efforts, our intent is to contribute insights that can support large‐scale restoration actions not only in Australia but also on a global scale. [ABSTRACT FROM AUTHOR]

In the Caribbean, reef-building scleractinian corals have declined precipitously and octocorals have emerged as one of their main successors. The success of octocorals and the formation of octocoral forests has been attributed to their continuing recruitment to reef habitats, as well as tolerance to pollution, reduced direct competition with scleractinians, and resistance and resilience to climatic events. Benthic grazers on coral reefs can facilitate the growth and recruitment of corals by reducing the abundance of competitive algal turfs and macroalgae. However, grazing can also hinder corals through sublethal damage to coral tissue and predation of recruits. We assessed the effects of grazing by fishes and the sea urchin Diadema antillarum as well as predation by mesofauna on octocoral recruitment through a series of manipulative in situ and ex situ experiments. Exposure to fish and urchin grazing significantly reduced the post-settlement survival of octocoral recruits, while turf-associated mesofauna did not significantly affect recruitment. We also found a positive relationship between octocoral recruitment and the abundance of turf algae, which may reflect the deleterious effect of grazing on both turf algae and octocoral recruits. These data suggest that grazers and predators mediate the bottleneck characteristic of recruitment, primarily through their effect on post-settlement survival. Thus, the declines in the abundance of grazing fishes and urchins throughout the Caribbean may have contributed to the increase in Caribbean octocoral abundance, concurrent with the loss of scleractinians. [ABSTRACT FROM AUTHOR]

Adaptation enables natural populations to survive in a changing environment. Understanding the mechanics of adaptation is therefore crucial for learning about the evolution and ecology of natural populations. We focus on the impact of random sweepstakes on selection in highly fecund haploid and diploid populations partitioned into two genetic types, with one type conferring selective advantage. For the diploid populations, we incorporate various dominance mechanisms. We assume that the populations may experience recurrent bottlenecks. In random sweepstakes, the distribution of individual recruitment success is highly skewed, resulting in a huge variance in the number of offspring contributed by the individuals present in any given generation. Using computer simulations, we investigate the joint effects of random sweepstakes, recurrent bottlenecks and dominance mechanisms on selection. In our framework, bottlenecks allow random sweepstakes to have an effect on the time to fixation, and in diploid populations, the effect of random sweepstakes depends on the dominance mechanism. We describe selective sweepstakes that are approximated by recurrent sweeps of strongly beneficial allelic types arising by mutation. We demonstrate that both types of sweepstakes reproduction may facilitate rapid adaptation (as defined based on the average time to fixation of a type conferring selective advantage conditioned on fixation of the type). However, whether random sweepstakes cause rapid adaptation depends also on their interactions with bottlenecks and dominance mechanisms. Finally, we review a case study in which a model of recurrent sweeps is shown to essentially explain population genomic data from Atlantic cod. [ABSTRACT FROM AUTHOR]

Fish species with high mortality during early life may maximize fitness using adaptive strategies to time hatching to match favorable environmental conditions (match/mismatch) or extending spawning/hatching to disperse risk (bet-hedging). We examined support for these strategies in a collapsed forage fish, capelin (Mallotus villosus), in coastal Newfoundland (2018–2021). Capelin shift from spawning at warm, intertidal to cool, subtidal (15–40 m) habitats in warmer years, with unknown recruitment consequences. We hypothesized that match/mismatch (specifically, Coastal Water Mass Replacement Hypothesis) would be supported if densities of recently hatched larvae showed pulses that overlapped with high prey and low predator densities. Generalized additive models revealed that larval densities increased with zooplankton prey biomass, but were not influenced by predator biomass or temperature, contrasting with pre-collapse studies and providing equivocal support for match/mismatch. Protracted larval emergence and previously documented high variability in larval traits supported a bet-hedging strategy. Larval condition (i.e. length, yolk-sac diameter) did not differ between habitats but varied among years, where the highest proportion of larvae in poor condition was from the intertidal site in the warmest year (2018). Findings suggest that spawning habitat shifts may have limited impact on stock recovery relative to year-specific environmental conditions that influence larval condition. [ABSTRACT FROM AUTHOR]

In the Caribbean, reef-building scleractinian corals have declined precipitously and octocorals have emerged as one of their main successors. The success of octocorals and the formation of octocoral forests has been attributed to their continuing recruitment to reef habitats, as well as tolerance to pollution, reduced direct competition with scleractinians, and resistance and resilience to climatic events. Benthic grazers on coral reefs can facilitate the growth and recruitment of corals by reducing the abundance of competitive algal turfs and macroalgae. However, grazing can also hinder corals through sublethal damage to coral tissue and predation of recruits. We assessed the effects of grazing by fishes and the sea urchin Diadema antillarum as well as predation by mesofauna on octocoral recruitment through a series of manipulative in situ and ex situ experiments. Exposure to fish and urchin grazing significantly reduced the post-settlement survival of octocoral recruits, while turf-associated mesofauna did not significantly affect recruitment. We also found a positive relationship between octocoral recruitment and the abundance of turf algae, which may reflect the deleterious effect of grazing on both turf algae and octocoral recruits. These data suggest that grazers and predators mediate the bottleneck characteristic of recruitment, primarily through their effect on post-settlement survival. Thus, the declines in the abundance of grazing fishes and urchins throughout the Caribbean may have contributed to the increase in Caribbean octocoral abundance, concurrent with the loss of scleractinians.

Despite the importance of recruitment for population dynamics and assessing stock status, limited information exists on the relative influence of various ecosystem and demographic factors on the recruitment dynamics of marine fishes. We develop a statistical framework to identify the ecosystem and demographic factors influencing the recruitment of marine fishes and facilitate improved predictions of recruitment. We demonstrate the approach by examining the relative influence of ecosystem and demographic factors on the recruitment of southern Gulf of St. Lawrence spring- and fall-spawning Atlantic herring (Clupea harengus) stocks, highlighting the benefit of considering multiple factors to better understand recruitment trends. We found that different combinations of biological and physical ecosystem factors along with demographic factors had a significant influence on the recruitment and recruitment rate of spring- and fall-spawning herring. The study emphasizes the value of considering ecosystem characteristics when examining recruitment, provides a framework for researchers to investigate and model recruitment of other fish populations, and supports the continued development and implementation of ecosystem-based fisheries management approaches for species, such as Atlantic herring. [ABSTRACT FROM AUTHOR]

Florida promotes itself as the fishing capital of the world, and fishing is one of the state's most popular recreational activities. As the state faces increasing anthropogenic and natural environmental stressors, effective resource management is of paramount importance in sustaining healthy fisheries. The Fisheries Independent Monitoring (FIM) program of the Florida Fish and Wildlife Conservation Commission's Fish and Wildlife Research Institute regularly monitors relative abundance of various size and age classes of multiple sport fish species (e.g., Centropomus undecimalis common snook, Sciaenops ocellatus red drum, Cynoscion nebulosus spotted seatrout) to provide timely data to fisheries managers. The FIM program samples seven major Florida estuaries, including four that the National Estuary Program has designated as estuaries of national significance (Tampa Bay, Sarasota Bay, Coastal and Heartland, and Indian River Lagoon). Although the FIM program sampling design is consistent and results are comparable among estuaries, the environmental perturbations, available habitats, habitat use by resource species, and recruitment dynamics vary, which can result in different abundance trends among estuaries. The goal of this study was to assess the role of early life stages as refuges for adult populations for two inshore sport fish species and examine their potential in forecasting relative abundance of fishery stocks. We present long-term abundance trends and assess lagged regressions among size or age classes to reveal the importance of size class refuges and identify preferred habitats that are estuary- and age class-specific, providing tools for better managing fishery stocks and habitats. [ABSTRACT FROM AUTHOR]

Evolutionary ecology may be described as explaining ecology through evolution and vice versa, but one may also view it as an integration of the two fields, where one takes the view that ecology and evolution are inseparable, and one can only begin to understand the biology of organisms by synthesizing the two fields. An example of such a synthesis is the biology of high fecundity and the associated concept of sweepstakes reproduction, or skewed individual recruitment success. As an illustration, we consider selection at linked sites under various dominance and epistasis mechanisms in a diploid population evolving according to random sweepstakes and experiencing recurrent bottlenecks. Using simulations, we give a few examples of the impact of the stated elements on selection. We show that depending on the dominance mechanisms, random sweepstakes can shorten the time to fixation (conditional on fixation) of the fit type at all sites. Bottlenecks tend to increase the fixation time, with random sweepstakes counteracting the effects of bottlenecks on the fixation time. Understanding the effect of random sweepstakes, recurrent bottlenecks, dominance mechanisms and epistasis on the fate of selectively advantageous mutations may help with explaining genetic diversity in natural highly fecund populations possibly evolving under sweepstakes reproduction. [ABSTRACT FROM AUTHOR]

Highly fecund natural populations characterized by high early mortality abound, yet our knowledge about their recruitment dynamics is somewhat rudimentary. This knowledge gap has implications for our understanding of genetic variation, population connectivity, local adaptation, and the resilience of highly fecund populations. The concept of sweepstakes reproductive success, which posits a considerable variance and skew in individual reproductive output, is key to understanding the distribution of individual reproductive success. However, it still needs to be determined whether highly fecund organisms reproduce through sweepstakes and, if they do, the relative roles of neutral and selective sweepstakes. Here, we use coalescent-based statistical analysis of population genomic data to show that selective sweepstakes likely explain recruitment dynamics in the highly fecund Atlantic cod. We show that the Kingman coalescent (modelling no sweepstakes) and the Xi-Beta coalescent (modelling random sweepstakes), including complex demography and background selection, do not provide an adequate fit for the data. The Durrett–Schweinsberg coalescent, in which selective sweepstakes result from recurrent and pervasive selective sweeps of new mutations, offers greater explanatory power. Our results show that models of sweepstakes reproduction and multiple-merger coalescents are relevant and necessary for understanding genetic diversity in highly fecund natural populations. These findings have fundamental implications for understanding the recruitment variation of fish stocks and general evolutionary genomics of high-fecundity organisms.

After 60 years of armed conflict in Colombia, a groundbreaking peace agreement was signed in 2016 between the FARC- EP guerrilla and the Colombian government. This agreement was endorsed by various international organizations and included progress on the restitution of the rights of child victims of forced recruitment. Five years after the signing of this agreement and with the FARC-EP's disarmament process completed, it was expected that recruitment would be reduced in the areas where the guerrillas exercised control, however, this paper will show why this is not a closed issue. Mainly because the territories that had been occupied by the FARC-EP did not receive the institutional deployment that was expected, both on the part of the public forces and the institutional and social offer. The aim is to provide a general overview of the problem of forced recruitment in Colombia in order to detail its impact on the department of Chocó. This border region between Colombia and Panama has been plagued for years by an armed conflict that is still latent. The main historical milestones of recruitment and the dynamics of recruitment in the Colombian territories will also be reviewed. [ABSTRACT FROM AUTHOR]

Sustainable human exploitation of living marine resources stems from a delicate balance between yield stability and population persistence to achieve socioeconomic and conservation goals. But our imperfect knowledge of how oceanic oscillations regulate temporal variation in an exploited species can obscure the risk of missing management targets. We illustrate how applying a management policy to suppress fluctuations in fishery yield in variable environments (prey density and regional climate) can present unintended outcomes in harvested predators and the sustainability of harvesting. Using Atlantic cod (Gadus morhua, an apex predatory fish) in the Barents Sea as a case study we simulate age‐structured population and harvest dynamics through time‐varying, density‐dependent and density‐independent processes with a stochastic, process‐based model informed by 27‐year monitoring data. In this model, capelin (Mallotus villosus, a pelagic forage fish), a primary prey of cod, fluctuations modulate the strength of density‐dependent regulation primarily through cannibalistic pressure on juvenile cod survival; sea temperature fluctuations modulate thermal regulation of cod feeding, growth, maturation, and reproduction. We first explore how capelin and temperature fluctuations filtered through cod intrinsic dynamics modify catch stability and then evaluate how management to suppress short‐term variability in catch targets alters overharvest risk. Analyses revealed that suppressing year‐to‐year catch variability impedes management responses to adjust fishing pressure, which becomes progressively out of sync with variations in cod abundance. This asynchrony becomes amplified in fluctuating environments, magnifying the amplitudes of both fishing pressure and cod abundance and then intensifying the density‐dependent regulation of juvenile survival through cannibalism. Although these transient dynamics theoretically give higher average catches, emergent, quasicyclic behaviors of the population would increase long‐term yield variability and elevate overharvest risk. Management strategies that overlook the interplay of extrinsic (fishing and environment) and intrinsic (life history and demography) fluctuations thus can inadvertently destabilize fish stocks, thereby jeopardizing the sustainability of harvesting. These policy implications underscore the value of ecosystem approaches to designing management measures to sustainably harvest ecologically connected resources while achieving socioeconomic security. [ABSTRACT FROM AUTHOR]

Aims: We studied the regeneration dynamics of woodlands and abandoned old fields in a landscape dominated by Quercus suber in its lower limits of rainfall and temperature. Two hypotheses were established: (1) regeneration of Quercus species is strongly favored by the presence of tree cover; and (2) growth of Q. suber is driven by the climatic variables that represent the lower ecological limit of its leading distribution edge. Methods: We selected woodlands and old fields with and without tree remnants (n = 3 per type), and analyzed stand structure, soil parameters and tree growth. Results: Succession was arrested in old fields without tree remnants. By contrast, remnant trees were accelerators of forest recovery in old fields. Tree cover played a fundamental role in Quercus recruitment throughout seed dispersal and facilitation that mitigate the effects of summer drought on seedlings. Also, tree cover improved soil parameters (e.g., organic matter) that are important factors for understanding differences in regeneration. Winter/spring precipitation exerted a positive effect on tree growth, as well as temperatures during winter/spring and September. Conclusions: Regeneration dynamics are modeled by the density of tree cover in the cold and dry edge of the distribution area of Q. suber where Q. ilex is increasing in abundance. Although temperature has a positive effect on the tree growth of Q. suber, when demographic processes are considered, decreases in water availability likely play a critical role in Q. ilex recruitment. This in turn changes dominance hierarchies, especially in abandoned areas with little or no tree cover. [ABSTRACT FROM AUTHOR]

Recruitment in age‐structured stock assessment models can be forecasted using a variety of algorithms to provide advice on the anticipated consequences of different possible management actions. Selecting one method over another usually involves some subjectivity, yet can be consequential to the provision of advice. Extensive case‐specific testing is not always feasible. We evaluated the forecast skill in 3‐, 5‐ and 10‐year forecasts of 16 recruitment forecasting methods under various circumstances to provide a broad evaluation and general guidelines on the reliability of forecasts. We used 31 operating models based on existing stock assessment models applied to a diversity of stocks with empirical data, which we show to be generally representative of assessed stocks worldwide. Although no single best‐performing method could be identified, we found that time‐series methods were most likely to perform poorly. Both forecast skill across all methods and forecast sensitivity to the selected method were linked to the properties of the stock or assessment: age at maturity and recruitment autocorrelation in 3‐year forecasts and previous long‐term recruitment variability in 10‐year forecasts. In some situations, all forecasting methods resulted in systematic over‐ or underestimation of spawning stock biomass. The simulation approach employed here to assess forecast performance, rooted directly in the predictions of existing stock assessment models, can be a complementary tool to existing simulation approaches which generate alternative sets of population dynamics or observations and we discussed the advantages and limitations. [ABSTRACT FROM AUTHOR]

Recruitment plays a vital role in the ecological and evolutionary successes of social insect colonies. In this paper, we formulate a four-compartment model and its simplified version to explore how we should model the recruitment dynamics of workers in social insect colonies properly. Our four-compartment model has the components of the unalarmed patrollers, the alarmed patrollers, the alarmed recruiters, and the available workers, while its simplified version has three components where we combine the unalarmed patrollers and the alarmed patrollers into the patrollers. We perform complete mathematical and bifurcation analyses on both the full system and its simplified system. We have many interesting findings, including that (i) the simplified three-compartment system has only simple equilibrium dynamics, i.e., no periodic and chaotic dynamics; (ii) the fourcompartment system has very complex dynamics; for example, it can have up to three subcritical Hopf bifurcations, two supercritical Hopf bifurcations, two limit point bifurcations, and a fold bifurcation of the limit cycle. Those important results provide theoretical guidance for modeling and studying recruitment dynamics of social insect colonies: It is critical to have proper compartments for biological systems as the number of compartments could lead to totally different dynamics, and hence affect policy-making. [ABSTRACT FROM AUTHOR]

For decades, fisheries have been managed to limit the accidental capture of vulnerable species and many of these populations are now rebounding. While encouraging from a conservation perspective, as populations of protected species increase so will bycatch, triggering management actions that limit fishing. Here, we show that despite extensive regulations to limit sea turtle bycatch in a coastal gillnet fishery on the eastern United States, the catch per trip of Kemp’s ridley has increased by more than 300% and green turtles by more than 650% (2001–2016). These bycatch rates closely track regional indices of turtle abundance, which are a function of increased reproductive output at distant nesting sites and the oceanic dispersal of juveniles to near shore habitats. The regulations imposed to help protect turtles have decreased fishing effort and harvest by more than 50%. Given uncertainty in the population status of sea turtles, however, simply removing protections is unwarranted. Stock-assessment models for sea turtles must be developed to determine what level of mortality can be sustained while balancing continued turtle population growth and fishing opportunity. Implementation of management targets should involve federal and state managers partnering with specific fisheries to develop bycatch reduction plans that are proportional to their impact on turtles. [ABSTRACT FROM AUTHOR]

Japanese eel larvae are passively transported to the East Asian Continental Shelf by the North Equatorial Current, Kuroshio and Kuroshio intrusion currents, and coastal currents. Previous studies have investigated the dispersal characteristics and pathways of Japanese glass eels. However, there are still limitations in these studies. According to long-term (2010–2020) catch data from the Fisheries Agency in Taiwan, the distribution and time series of glass eels recruitment to Taiwan are closely related to the surrounding ocean currents. Recruitment begins in eastern Taiwan via the mainstream Kuroshio and in southern Taiwan via the Taiwan Strait Warm Current. In central Taiwan, recruitment occurs from southern Taiwan, as well as from mainland China via the southern branch of the China Coast Current (CCC). The latest recruitment occurred in northern Taiwan and mainly comprised glass eels from mainland China via the northern branch of the CCC. A stronger monsoon during the La Niña phase could affect the recruitment time series in northern and eastern Taiwan. This study suggests that the recruitment directionality of glass eels is an indicator of the flow field of ocean/coastal currents and elucidates the dispersal characteristics of glass eels in the waters around Taiwan.

Seed dispersal and subsequent recruitment dynamics play a crucially important role in regulating species coexistence and structuring tree diversity in diverse forests. Wildlife, which can dually shape the tree recruitment process by simultaneously functioning as natural enemies and seed dispersers, are undergoing widespread changes in population and behaviour due to the detrimental effects of expanding global road networks. However, the impact of these changes on recruitment dynamics through the alteration of seed dispersal processes remains understudied.Here, we assessed how roads affect animal‐mediated recruitment dynamics from the seed to adult stages of trees using a ubiquitous vertebrate‐seed model: rodents and acorns. To quantify the degree to which proximity to a road alters seed dispersal and regulates subsequent recruitment dynamics, we conducted seed dispersal and predation experiments, and investigated the natural recruitment of a dominant tree species (Quercus aliena) from September 2009 to July 2012 in a subtropical forest of central China.Roads caused a decreased seed dispersal distance and increasing larder hoarding, demonstrating a weakened contribution of rodents to seed dispersal services. These patterns were stronger in the masting year than in the non‐masting year. Correspondingly, seedlings, saplings and adult trees had higher densities near roads than far from roads. Near roads, recruit transition rates (i.e. seedling‐to‐sapling and sapling‐to‐juvenile) were low, and the influential strength of conspecific adult density was weakened over these recruit transitions, indicating that space limitation and lottery competition, not conspecific negative density‐dependent effects, approximately determined the near‐road recruitment process. Furthermore, most adults near roads were young, and their ages matched the road ages.Synthesis. Roads diminished animal‐mediated seed dispersal services and disrupted subsequent recruitment dynamics in Quercus aliena populations, thus weakening the key process promoting diversity in forest ecosystems. Given that these animal‐regulated roles in recruitment dynamics are widespread stabilizing forces for tree coexistence, our findings suggest that the ubiquity of roads and their continued expansion will contribute to the increase in forests dominated by a relatively low number of species. Consequently, the growing expansion of road networks will ultimately cause profound changes in community composition and structure across diverse forests worldwide. [ABSTRACT FROM AUTHOR]

The importance of survival and growth variations early in life for population dynamics depends on the degrees of compensatory density dependence and size dependence in survival at later life stages. Quantifying density‐ and size‐dependent mortality at different juvenile stages is therefore important to understand and potentially predict the recruitment to the population. We applied a statistical state‐space modelling approach to analyse time series of abundance and mean body size of larval and juvenile fish. The focus was to identify the importance of abundance and body size for growth and survival through successive larval and juvenile age intervals, and to quantify how the dynamics propagate through the early life to influence recruitment. We thus identified both relevant ages and mechanisms (i.e. density dependence and size dependence in survival and growth) linking recruitment variability to early life dynamics. The analysis was conducted on six economically and ecologically important fish populations from cold temperate and sub‐arctic marine ecosystems. Our results underscore the importance of size for survival early in life. The comparative analysis suggests that size‐dependent mortality and density‐dependent growth frequently occur at a transition from pelagic to demersal habitats, which may be linked to competition for suitable habitat. The generality of this hypothesis warrants testing in future research. [ABSTRACT FROM AUTHOR]

Abstract The population dynamics of forage fish are often 'boom or bust', and variation in recruitment may be a contributing factor to changes in abundance. Here we applied several methods for identifying stock recruit relationships (SRR) to 52 forage fish stocks: a time-invariant Ricker model and two time-varying methods (dynamic linear models and regime-based models). A positive relationship between spawning biomass and recruitment existed for 28 stocks, with 14 of those being best fit by a Ricker curve. Time-varying models were preferred for 26 stocks over a time-invariant Ricker curve. We also showed through simulation that spurious, yet significant stock-recruit relationships can be generated if recruitment was environmentally driven, the lag between recruitment and spawning biomass was small, and autocorrelation in recruitment was high—a combination of characteristics that many forage fish stocks display. Based on our results, observed time-invariant SRRs can result from a reversed causality of 'boom and bust' dynamics in situations in which life histories are short (i.e., changes in recruitment are driving changes in spawning biomass). 'Hidden' SRRs are also possible because of time-variation in SRR parameters. Understanding when each of these potential failings of fitting SRRs can occur is a key challenge in forage fish management. [ABSTRACT FROM AUTHOR]

Recruitment dynamics are challenging to assess or predict because of the many underlying drivers that vary in their relevance over time and space. Stock size, demographic and trait composition, condition and distribution of spawning fish and the spatio‐temporal dynamics of trophic and environmental interactions all influence recruitment processes. Exploring common patterns among stocks and linking them to potential drivers may therefore provide insights into key mechanisms of recruitment dynamics. Here, we analysed stock‐recruitment data of 64 stocks from the north‐east Atlantic Ocean for common trends in variation and synchrony among stocks using correlation, cluster and dynamic factor analyses. We tested common trends in recruitment success for relationships with large‐scale environmental processes as well as stock state indicators, and we explored links between recruitment success and demographic, environmental and ecological variables for a subset of individual stocks. The results revealed few statistically significant correlations between stocks but showed that underlying common trends in recruitment success are linked to environmental indices and management indicators. Statistical analyses confirmed previously suggested relationships of environmental–ecological factors such as the subpolar gyre and Norwegian coastal current with specific stocks, and indicated a large relevance of spawning stock biomass and demographics, as well as predation, whereas other suggested relationships were not supported by the data. Our study shows that despite persistent challenges in determining drivers of recruitment due to poor data quality and unclear mechanisms, combining different data analysis techniques can improve our understanding of recruitment dynamics in fish stocks. [ABSTRACT FROM AUTHOR]

Abstract Palatable shrubs and trees in rangelands are vulnerable to grazing impacts, with local extinctions and declines documented. However, population trends are difficult to detect due to longevity of individuals and poor understanding of regeneration. We investigated the demography and conservation status of the Grey Range fuchsia (Eremophila stenophylla Chinnock), a geographically restricted and palatable shrub endemic to south-west Queensland. We documented 28 populations over 30,400 km2, with an estimated total population size of 17,000 individuals. Seedling recruitment is rare and seedlings were observed at six populations, all with low or intermittent grazing pressure. In contrast, vegetative recruits were recorded at 19 populations and comprised at least 28% of plants measured. Resprouting confers some resilience to individuals, although repeated browsing restricts plant growth, limiting flowering and fruiting. Consistently heavily grazed populations also contain fewer plants. Although Eremophila stenophylla is secure in numerous populations with low grazing pressure, it qualifies as Vulnerable under IUCN Red List criteria due to past and ongoing decline at more than half of its populations. Grazing relief is necessary to ensure the long-term persistence of these populations. We predict that similar trajectories apply to other semi-arid shrubs, and research is required to inform grazing management to avert local extinctions. Highlights • Eremophila stenophylla is a heavily-browsed, geographically restricted rangeland shrub. • Resprouting confers some resilience but browsing restricts plant growth, fecundity and recruitment. • Heavily grazed populations contain fewer plants. • Grazing relief is necessary to ensure long-term persistence of populations. • Palatable perennials are vulnerable to declines and research is needed to inform appropriate grazing management. [ABSTRACT FROM AUTHOR]

Abstract: Gulf (Brevoortia patronus, Clupeidae) and Atlantic menhaden (Brevoortia tyrannus, Clupeidae) support large fisheries that have shown substantial variability over several decades, in part, due to dependence on annual recruitment. Nevertheless, traditional stock–recruitment relationships lack predictive power for these stocks. Current management of Atlantic menhaden explicitly treats recruitment as a random process. However, traditional methods for understanding recruitment variability carry the very specific hypothesis that the effect of adult biomass on subsequent recruitment occurs independently of other ecosystem factors such as food availability and predation. Here, we evaluate the predictability of menhaden recruitment using a model‐free approach that is not restricted by these strong assumptions. We find that menhaden recruitment is predictable, but only when allowing for interdependence of stock with other ecological factors. Moreover, while the analysis confirms the presence of environmental effects, the environment alone does not readily account for the complexity of menhaden recruitment dynamics. The findings set the stage for revisiting recruitment prediction in management and serve as an instructive example in the ongoing debate about how to best treat and understand recruitment variability across species and fisheries. [ABSTRACT FROM AUTHOR]

The best-known mechanism that herbivory affects species coexistence of tree seedlings is negative density-dependency driven by specialist natural enemies. However, in a forest with intense herbivory by non-specialists, what causes a diversifying seedling bank if rare species do not benefit from negative density-dependency in dominant species? We hypothesize that generalist herbivores can cause unevenly distributed species-specific mortality, which mediates recruitment dynamics and therefore affects species coexistence. To answer this question, we conducted a fence-control experiment in a montane cloud forest, Taiwan, and found that herbivorous damages were mainly caused by ungulates, which are generalists. We explored ungulate herbivory effects on recruitment dynamics by censusing tree seedling dynamics for three years. We found that herbivorous damages by ungulates significantly cause seedling death, mostly at their early stage of establishment. The percentage of death caused by herbivory varied among species. In particular, nurse plants and seedling initial height help shade-tolerant species to persist under such intense herbivory. Whereas, deaths caused by other factors occurred more often in older seedlings, with a consistent low percentage among species. We then tested species coexistence maintenance by dynamic modelling under different scenarios of ungulate herbivory. Raising percentages of death by herbivory changes relative species abundances by suppressing light-demanding species and increasing shade-tolerant species. Density-dependent mortality immediately after bursts of recruitments can suppress dominance of abundant species. With ungulate herbivory, fluctuating recruitment further prevent rare species from apparent competition induced by abundant species. Such bio-processes can interact with ungulate herbivory so that long-term coexistence can be facilitated. [ABSTRACT FROM AUTHOR]

We applied a management strategy evaluation (MSE) model to examine the potential cost-effectiveness of using pheromone-baited trapping along with conventional lampricide treatment to manage invasive sea lamprey. Four pheromone-baited trapping strategies were modeled: (1) stream activation wherein pheromone was applied to existing traps to achieve 10−12 mol/L in-stream concentration, (2) stream activation plus two additional traps downstream with pheromone applied at 2.5 mg/hr (reverse-intercept approach), (3) trap activation wherein pheromone was applied at 10 mg/hr to existing traps, and (4) trap activation and reverse-intercept approach. Each new strategy was applied, with remaining funds applied to conventional lampricide control. Simulating deployment of these hybrid strategies on fourteen Lake Michigan streams resulted in increases of 17 and 11% (strategies 1 and 2) and decreases of 4 and 7% (strategies 3 and 4) of the lakewide mean abundance of adult sea lamprey relative to status quo. MSE revealed performance targets for trap efficacy to guide additional research because results indicate that combining lampricides and high efficacy trapping technologies can reduce sea lamprey abundance on average without increasing control costs. [ABSTRACT FROM AUTHOR]

Balanced fishing proposes a considerable change to current fisheries management to increase overall biomass harvested while reducing the ecosystem impacts of large-scale fisheries. However, to date, the work to a large degree has focused on simplified models, which exclude much of the variability in real ecosystems, as well as basing harvesting rates on a perfect, but unrealistic, knowledge on stock productivity. Furthermore, the published studies have avoided examining the practicalities of implementing balanced fishing in a real world. This has resulted in a gap that remains to be overcome before balanced fishing can be considered a viable management strategy for large marine ecosystems.Wediscuss variability in recruitment, in biology and life history characteristics, in data quality, and in fishing practice and management, and their implications for implementation of balanced fishing, using examples from the Barents Sea. We try to outline the complexities that need to be investigated as a precursor tomoving balanced fishing from an academic exercise to a practical management scheme. Given the difficulties in moving to "full" balanced fishing, we highlight the importance of investigating to what extent benefits can be gained by implementing only the most achievable parts of a balanced fishing regime. [ABSTRACT FROM AUTHOR]

• Natural and human disturbances in old forests with contrasting management history. • Forest dynamics analysed with dendroecology and a dynamic vegetation model. • Persistence and dominance of shade-tolerant species under low disturbance rates. • Management legacies affect composition and structure, increasing fir abundance. • Natural disturbances induce temporal fluctuations of beech and fir abundance. Ecological knowledge on long-term forest dynamics and development has been primarily derived from the study of old-growth forests. Centuries of forest management have decreased the extent of temperate old-growth forests in Europe and altered managed forests. Disentangling the effects of past human disturbances and climate on current species composition is crucial for understanding the long-term development of forests under global change. In this study, we investigated disturbance and recruitment dynamics in two forests in the Western Pyrenees (Spain) with contrasting management history: an old-growth forest and a long-untouched forest, both dominated by the two shade-tolerant species Fagus sylvatica (European beech) and Abies alba (Silver fir). We used dendroecological methods in seven plots to analyse forest structure, growth patterns and disturbance histories in these forests. We benchmarked these data with the dynamic vegetation model ForClim to examine the effects of natural and human-induced disturbances on forest development, structure and species composition. Disturbance regimes differed between the study forests, but none showed evidence of stand replacing disturbances, either natural or human induced. Low disturbance rates and continuous recruitment of beech and fir dominated the old-growth forest over the last 400 years. In contrast, the long-untouched forest was intensively disturbed in 1700–1780, probably by logging, with lower natural disturbance rates thereafter. Beech and fir recruitment preferentially occurred after more intense disturbances, despite the high shade tolerance of both beech and fir. Higher fir abundance in the long-untouched forest than in the old-growth forest appeared to be related to its human-induced disturbances. ForClim closely simulated forest potential natural vegetation with a dominance of beech over fir, but overestimated the presence of less shade-tolerant species. Previously observed local fir decline may result from natural forest successional processes after logging. Within ∼200 years after logging cessation, some long-untouched forest structural attributes converged towards old-growth forest, but legacy effects still affected species composition and structure. Natural disturbance regimes in beech-fir forests of the Western Pyrenees induce temporal fluctuations between beech and fir abundance, with a natural tendency for beech dominance in advanced developmental stages with low disturbance rates. [ABSTRACT FROM AUTHOR]

In fishes, the growth-mortality hypothesis has received broad acceptance as a driver of recruitment variability. Recruitment is likely to be lower in years when the risk of starvation and predation in the larval stage is greater, leading to higher mortality. Juvenile snapper, Pagrus auratus (Sparidae), experience high recruitment variation in Port Phillip Bay, Australia. Using a 5-year (2005, 2007, 2008, 2010, 2011) data set of larval and juvenile snapper abundances and their daily growth histories, based on otolith microstructure, we found selective mortality acted on larval size at 5 days post-hatch in 4 low and average recruitment years. The highest recruitment year (2005) was characterised by no size-selective mortality. Larval growth of the initial larval population was related to recruitment, but larval growth of the juveniles was not. Selective mortality may have obscured the relationship between larval traits of the juveniles and recruitment as fast-growing and large larvae preferentially survived in lower recruitment years and fast growth was ubiquitous in high recruitment years. An index of daily mortality within and among 3 years (2007, 2008, 2010), where zooplankton were concurrently sampled with ichthyoplankton, was related to per capita availability of preferred larval prey, providing support for the match-mismatch hypothesis. In 2010, periods of low daily mortality resulted in no selective mortality. Thus both intra- and inter-annual variability in the magnitude and occurrence of selective mortality in species with complex life cycles can obscure relationships between larval traits and population replenishment, leading to underestimation of their importance in recruitment studies. [ABSTRACT FROM AUTHOR]

Highlights: [•] We investigated impacts of alien grass invasion on endangered coastal seed bank communities. [•] Invasion caused moderate declines in native seed bank richness and density. [•] Species losses varied amongst growth forms and dispersal strategies. [•] Assisted species reintroductions may be needed to facilitate community recovery following invasion. [Copyright &y& Elsevier]

• Community structure of copepod species changed over the 19-year study period. • Biomass of cool-water copepod species markedly decreased in the last decade. • Elevated temperature and declining chlorophyll a levels were recently observed. • Condition factor of females and egg size of anchovy decreased over the period. • Maternal prey availability of anchovy significantly affected offspring viability. Anthropogenic and/or climate-driven changes in zooplankton dynamics may serve as a bottom-up regulator of productivity of small pelagic fish. In the central Seto Inland Sea of Japan, the abundance of the recruit fish of Japanese anchovy (Engraulis japonicus) has markedly declined in the last decade under oligotrophication. However, the link between the reproductive success of anchovy and environmental variation is largely unclear. This study explored the potential association between changes in the zooplankton (copepods) community structure and the reproductive condition of anchovy in this oligotrophic sea using survey data from spring to summer of 2001–2019. The community structure of copepod species changed markedly in May–July, covering the main spawning season of anchovy, as decreases in the biomass of several copepods found in cooler water in a given season (May–June) were observed. Although relationships between chlorophyll a concentrations and the copepod biomass were unclear, the recent decline of their cooler-water copepods may be attributed to the influences of elevated sea surface temperature and decreasing levels of chlorophyll a. The latter may be associated with decreasing nitrogen levels. Among these species, Calanus sinicus and Corycaeus affinis could be important prey items for anchovy from the analyses of prey selectivity and relationships between the relative condition factor of females and the copepod biomass. The egg size–temperature relationships of anchovy appeared to be associated with the relative condition factor of females and survival rates in the early stage of life, suggesting that females with a poor body condition produced smaller eggs in recent years. Maternal food manipulation experiments supported the assumption that larvae born to females fed a restricted food ration exhibited lower starvation tolerance and slower growth than born to females provided feed ad libitum. These findings suggest that the reproductive success of anchovy could be subject to bottom-up trophic drivers mediated by maternal contributions to offspring viability, and this partly explains why the level of anchovy recruitment has rapidly declined in the last decade. [ABSTRACT FROM AUTHOR]

Most studies of soil heterogeneity have focused on underlying abiotic factors such as soil nutrients. However, increasing recognition of plant-soil feedback ( PSF) effects on plant growth, combined with the observation that PSFs operate at small spatial scales, suggests that heterogeneity due to PSF could affect plant population and community dynamics. The consequences of PSF-generated heterogeneity for coexistence depend on heterogeneity's effects on vital rates and how those vital rates influence population-level recruitment dynamics., We measured vital rates and recruitment dynamics of three congeneric pairs of introduced perennial plants grown as monocultures in experimental PSF-generated soil environments. Field soils collected from conspecifics and congeners were alternated in patches or mixed together to produce heterogeneous and homogeneous soils, respectively., We quantified the effects of PSF-generated heterogeneity on germination and establishment and determined how these vital rates affected recruitment. We calculated net pairwise interaction coefficients to predict whether PSFs could mediate coexistence between congeners., Soil heterogeneity altered the relationship of vital rates to recruitment dynamics for some species. For example, Solanum dulcamara recruited later into heterogeneous than homogeneous soils, and germination was a stronger predictor of the timing of recruitment in heterogeneous soil, while mortality was a stronger predictor in homogeneous soil. Contrasts between soils of different origin suggest that mixing soils had non-additive effects on vital rates (e.g. Rumex crispus mortality was higher in homogeneous than in conspecific or congener soil). Interaction coefficients predicted that PSFs in heterogeneous soils might mediate stable coexistence only of Rumex congeners., Synthesis. Heterogeneity generated by PSFs had species-specific effects on vital rates, with consequences for recruitment dynamics. Mixing soils of different origin often resulted in non-additive effects, which may indicate an interaction between soil abiotic and/or biotic properties and could predict non-additive responses to soil disturbance. Finally, quantifying the reciprocal effects of PSFs on congeners suggests that PSF-generated heterogeneity may promote coexistence of certain species, which was not evident from individual PSF responses. Future studies should determine whether such mechanisms might operate for more distantly related species. [ABSTRACT FROM AUTHOR]

Animal population dynamics can be driven by rainfall variability through its influence on habitat suitability, availability and nutritional sufficiency of forage. To understand how rainfall influences ostriches, we related changes in ostrich recruitment in the Mara–Serengeti ecosystem to rainfall. Over a 15-year period, monthly counts of ostriches were made and the number of hatchlings, chicks, hens, cocks, and the size of the groups in which they occurred were recorded. Breeding was bimodal with a major peak in February and a minor peak in October. Ostriches formed larger groups in the wet (4.41 ± 5.17 (mean ± SD), range 1–72,n =672 groups) than in the dry (2.49 ± 2.70, range 1–29,n =398) season. The number of hatchlings plus chicks per hen increased across the duration of the study period and with increasing annual and early wet-season rainfall, affecting forage availability and quality. Recruitment was highest at intermediate levels of the five-year average of the late wet-season rainfall, implying that a change in long-term rainfall and habitat suitability would move recruitment away from the optimum. Outstanding adaptations to life in arid environments could make ostriches more resilient than sympatric ungulates if food shortages and water stress became more frequent because of widening climatic variability. [ABSTRACT FROM AUTHOR]

Abstract: The negative effect of conspecific trees on seedling recruitment in temperate forests has been well documented at the population level for several common species. In 2007, we estimated the survival of 2210 recently germinated seedlings of nine tree species transplanted near conspecific and heterospecific trees, a surrogate for describing distance-dependent mortality, as part of an experiment with landscape-level replication across eight mixed-deciduous forests in the southern Appalachian Mountains of North Carolina. Forest composition was variable but they had a number of woody species in common. Prior to establishing the field experiment, we used a forest inventory database for the region to classify the recruitment patterns of tree species and formulate predictions for species. The field experiment, conducted as a drought was progressing, revealed that four of the nine species planted had variable survival around conspecifics compared with heterospecifics suggesting variation in distance-dependent mortality. Acer saccharum and Tsuga canadensis both had greater mortality near conspecifics than heterospecifics, while Fagus grandifolia and Prunus serotina showed the opposite pattern. Species classified as having greater recruitment around conspecifics, according to the forest inventory data, suffered greater overall levels of mortality in our field experiment. Possibly because of the progressing drought, none of the four species predicted to be most affected by distance-dependent sources of mortality based on the forest inventory data exhibited the predicted patterns of survival near conspecific vs. heterospecific trees in the field experiment. Furthermore, two of the four species (A. saccharum and T. canadensis) classified as being least affected by conspecific trees actually had greater survival near heterospecifics than conspecifics. Although we identified effects of canopy tree type in four of the nine comparisons, negative effects of conspecific trees were observed for only two (A. saccharum and T. canadensis) of nine species and mostly contradicted predictions based on patterns from forest inventory data. The inconsistency between patterns from the forest inventory data and from experiments indicates that there may be localized, complex interactions that make generalizations about neighbor effects on tree seedling survival difficult. [Copyright &y& Elsevier]

Since climate change projections contain many uncertainties and are normally unable to predict the direction and magnitude of change at the small scale needed by forest managers, some understanding about the functioning of the target forest should be obtained before a robust management strategy can be applied. Structure and regeneration patterns are related to key ecosystem processes which, on the other hand, can be modified by silvicultural treatments. In this research, the structure and recruitment dynamics of two stands with different histories of management were investigated in the southern limit of the range of Pinus nigra subsp. salzmannii (Southeast Spain). We described forest structure and facilitation effects by forest canopies and nurse shrubs, and quantified the processes affecting each stage of regeneration (dispersed seed, first year seedling and second year seedling) in different microhabitats. Forest structure was more complex in the stand scarcely influenced by human activities. Juniperus communis shrubs seemed to facilitate the establishment of tree saplings. Most seedlings died of desiccation during their first summer. At best, 190 out of 10,000 emerged seedlings survived the first summer. In light of these results, the possibilities of applying close-to-nature forestry in the study forests and other aspects of silviculture under a frame of adaptive forest management are discussed. [ABSTRACT FROM AUTHOR]

Hüssy, K. 2011. Review of western Baltic cod (Gadus morhua) recruitment dynamics. – ICES Journal of Marine Science, 68: 1459–1471.Important processes in the recruitment dynamics of western Baltic cod (Gadus morhua) are identified. Spawning areas are in the deep, saline waters below 20–40 m, depending on area topography. Spatial distribution remains relatively stable over time. Peak spawning shows an area-specific pattern, with progressively later spawning towards the east. Genetic stock structure and tagging indicate some degree of natal homing for spawning. The highly variable hydrodynamic conditions and the fact that cod eggs float in the water column cause their entrainment by currents, and their destination is determined by the prevailing winds and currents. Drift is almost exclusively to the east, but the magnitude and its impact on the structure of the affected stocks (Kattegat, western Baltic, and eastern Baltic) remains unresolved. Salinity limits the east–west exchange of eggs as a consequence of the stocks' differential requirement for neutral buoyancy. Superimposed on this, oxygen content and temperature have a significant effect on fertilization, egg/larva development, and survival. Within the Baltic Sea ecosystem, mixing of stocks may be anticipated and is particularly pronounced in the Arkona Basin because of its use for spawning by both western and eastern stocks, the advection of early life stages from the west and immigration/emigration from the east. [ABSTRACT FROM PUBLISHER]

Vincenzi S, Crivelli AJ, Jesensek D, De Leo GA. Individual growth and its implications for the recruitment dynamics of stream-dwelling marble trout ( Salmo marmoratus). Ecology of Freshwater Fish 2010: 19: 477–486. © 2010 John Wiley & Sons A/S The role of density-dependent individual growth in the recruitment dynamics of fish populations has rarely been analysed in a quantitative framework. Variations of mean size of juveniles in response to changes in population densities have frequently been observed in salmonids and it has been shown that body-size differences at the juvenile stage can persist through the sub-adult and adult stage. As fecundity and sexual maturation are often a function of body size, inter-cohort variations in individual growth may ultimately affect the reproductive output and, consequently, the amount of yearly recruitment. Here, we present a simulation analysis investigating the effects of density-dependent growth on the reproductive output and, ultimately, on the population dynamics of stream-dwelling salmonids. The demographic model used for the numerical analysis was parameterised using marble trout Salmo marmoratus as a reference species and explicitly accounted for the occurrence of major floods events causing the population to collapse to very low densities. Our simulations showed that density-dependent individual growth is a powerful mechanism to foster population resilience through compensatory recruitment. In addition, we argue that density-dependent growth also helps regulate recruitment at high population densities. We show that even slight variations in the growth trajectories of fish substantially affect the size and the dynamics of the population. [ABSTRACT FROM AUTHOR]

1. Plant recruitment is a multiphase process that takes place in environments that are heterogeneous in space and time. In this work, I analyse how environmental heterogeneity in Mediterranean forests affects dynamics of early recruitment at different scales, using the wind-dispersed tree Acer opalus subsp. granatense as a case study. 2. Seed dispersal and viability, post-dispersal predation, seedling emergence and seedling and sapling survival were evaluated in different habitats (regional scale) and microhabitats (local scale). Simultaneously, a review of the literature on spatial dynamics of plant recruitment in Mediterranean systems was conducted to look for general patterns and investigate their fit to the Acer system. Nineteen woody and herbaceous species were included in the review. 3. At the regional scale, Acer recruitment dynamics strongly converged among sites of the same habitat. This was mainly due to large seedling emergence and survival differences among habitats. Although most of the studies reviewed analyzed only one site per habitat type, they also support strong regional variation (either site- or habitat-specific) in recruitment patterns. 4. At the local scale, Acer recruitment was microhabitat-specific, a result shared by almost all the reviewed species independently of their life form and dispersal syndrome. This was mostly due to spatial differences in seed arrival (higher under conspecifics) and seedling survival (higher under nurse shrubs). 5. Spatial discordance among seed rain and recruitment was found in 60% of the reviewed species at the regional scale, and in 67% at the local scale. Acer results supported this predominant lack of concordance. Discordance among seed rain and recruitment suggests that regeneration is largely limited by safe sites than by seed availability. Because seedling survival was the limiting process with a larger impact on the magnitude and spatial pattern of recruitment, safe sites might be defined as those where seedlings have a higher survival probability. 6. Synthesis: This study indicates that the influence of seed dispersal on the spatial patterns and demography of plant species could be limited in heterogeneous and stressful environments (as are found in the Mediterranean), where recruitment is restricted to a small fraction of the landscape. If we are to preserve the distribution and abundance of Mediterranean species in the face of environmental changes, we need to explicitly consider the strong patch-specificity that characterizes their recruitment process at all scales. [ABSTRACT FROM AUTHOR]

Abstract: Surface velocity estimates from wind and altimeter data, together with satellite-derived sea surface temperature and chlorophyll, were used to explore the advection patterns and environmental conditions using a simple Lagrangian model. Although the model is generic (only considering the physical transport), the results are of particular interest for sardine (Sardina pilchardus) early life stages, due to the spawning dynamics of the species off Iberia and NW Africa. Particles were released on the shelf of the Iberian and northern African Atlantic coasts every five days from 1998 to 2004 and advected for 27-days. Trajectories were computed using combinations of three surface velocity constituents: Ekman velocity, geostrophic velocity derived from sea level anomaly maps and mean geostrophic velocity derived from two mean dynamic topographies. Daily time series of sea surface temperature, chlorophyll-a concentration and water depth where constructed for each particle trajectory. The results showed strong regional and seasonal dependence of the transport due to wind, with average seasonal cycles of the percentage of particles found in the shelf reflecting the anticipated effect of the seasonal north–south migration of the trade wind belt. The addition of the geostrophic transport led to the attenuation of seasonal cycles and higher mean/maximum values in the probability of retention within the shelf. This increased capacity for retention even during strong upwelling conditions seems to have been overlooked by theories aiming to describe the reproductive strategies of pelagic fish and understand recruitment dynamics based primarily on wind variability. On the other hand, the average surface chlorophyll values indicated a distribution area with higher primary production for particles that never leave the shelf, in comparison to those that return to it or are found in the open sea a month after release, which is in agreement with existing hypotheses that offshore advection is detrimental to larval survival mainly due to the higher risk of starvation. Finally, the exchange between adjacent shelf areas was generally small (less than 5%) within the study period, with the exception of the Gulf of Cadiz. In the latter area, up to 50% of particles released in the southern Iberian shelf reached the Moroccan shelf in several events, contradicting previous suggestions that the Strait of Gibraltar acts as a physical barrier that promotes genetic differentiation among neighbouring sardine populations in the Atlantic. Overall, these results provide useful insights for the study of sardine dynamics in the northeast Atlantic but the unexpectedly high sensitivity of summary metrics (namely retention probability) to the choice of surface velocity field preclude firm conclusions and indicate alternative routes for future studies. [Copyright &y& Elsevier]

• Background and Aims The relative importance of pre- and post-germination determinants for recruitment of natural plant communities is rarely explored. An annual plant community on moving sandy land was chosen for a case study. Answers to the following questions were sought: (a) Does recruitment of new individuals within the community of annual plants differ in time and space? (b) Is there spatial concordance between seed deposition, seedling emergence, survival and recruitment? (c) What are the direct and indirect effects of pre- and post-germination determinants on plant recruitment.• Methods An integrative approach combining investigation of natural recruitment processes with regression, correlation and path analyses was adopted. Data on seed deposition and seedling recruitment were collected by monitoring the number of seeds deposited in the top 5 cm of the soil and the numbers of seedlings emerged and recruited from all annual plants at sites to a range of distances from the existing shrub Artemisia halodendron (Asteraceae) in eight compass directions for two consecutive growing seasons.• Key Results Community-level recruitment was strongly affected by inter-annual rainfall variation and was highly site- and density-dependent. Low recruitment rate in this system was due to low emergence rate and low post-emergence survival rate. Of the pre- and post-germination determinants studied, it was the number of seedlings which emerged and the post-emergence survival rate that had the greatest direct effects on recruitment, with a combination of both variables explaining the majority of the variance (97 %) in recruitment.• Conclusions This study suggests that post-germination determinants (emergence and survival) rather than pre-germination determinants (seed deposition) substantially determined the final pattern of recruitment. Although the density of seeds deposited did not have a significant direct effect on recruitment, it contributed to observed variation in recruitment indirectly through density-dependent emergence of seedlings. [ABSTRACT FROM AUTHOR]

1 Recruitment in plant populations is a multiphase sequential process. An integrated view of the relationships between the stages and processes involved is therefore needed, but few studies have analysed the direct and indirect effects concerned. We propose a causal model of these relationships and use structural equation modelling (SEM) and path analysis to investigate the direct and indirect effects of pre- and post-germination processes on recruitment.2 We collected information on seed production, pre-dispersal seed losses, seed removal from the ground, seedling emergence and mortality, and seedling recruitment during the first year after emergence from 1 × 1 m plots centred on reproductive individuals in three geographically distant populations of the perennial herbHelleborus foetidus.3 The results suggest some congruence between the three populations and indicate that post-germination processes shape the spatial variation in recruitment more than pre-germination processes. Although between-plot variation in recruitment was mostly explained by seedling emergence and mortality, factors such as seed production and removal still have significant effects on recruitment through various, and frequently contrasting, pathways.4 Path analysis is a powerful analytical tool for revealing important aspects of the recruitment dynamics of plant populations and the factors determining their spatial variation. Such aspects, including indirect effects, are difficult to quantify with other, more classical, approaches to recruitment.Journal of Ecology(2004) doi: 10.1111/j.1365-2745.2004.00955.x [ABSTRACT FROM AUTHOR]

The article discusses the study on the old-growth structure of the forest dynamics on Wachusett Mountain in Massachusetts. It states that the forest were composed of mixture of Quercus rubra and northern hardwood species. It notes that the species abundances and recruitment dynamics exhibit variable spatial and temporal patterns across sites that differs in part and exposure. It mentions that the gnarled trees gave the forest resistance against severe winds from hurricanes.

Japanese eel larvae are passively transported to the East Asian Continental Shelf by the North Equatorial Current, Kuroshio and Kuroshio intrusion currents, and coastal currents. Previous studies have investigated the dispersal characteristics and pathways of Japanese glass eels. However, there are still limitations in these studies. According to long-term (2010–2020) catch data from the Fisheries Agency in Taiwan, the distribution and time series of glass eels recruitment to Taiwan are closely related to the surrounding ocean currents. Recruitment begins in eastern Taiwan via the mainstream Kuroshio and in southern Taiwan via the Taiwan Strait Warm Current. In central Taiwan, recruitment occurs from southern Taiwan, as well as from mainland China via the southern branch of the China Coast Current (CCC). The latest recruitment occurred in northern Taiwan and mainly comprised glass eels from mainland China via the northern branch of the CCC. A stronger monsoon during the La Niña phase could affect the recruitment time series in northern and eastern Taiwan. This study suggests that the recruitment directionality of glass eels is an indicator of the flow field of ocean/coastal currents and elucidates the dispersal characteristics of glass eels in the waters around Taiwan. [ABSTRACT FROM AUTHOR]

• Effects of growth rate on recruitment changed over time. • Baseline recruitment level also changed over time. • Time-varying relationship model was more statistically plausible than time-constant models. • Growth–recruitment relationship is more dynamic than previously recognized. Growth is an important factor that regulates survival during early life stages, and growth rates and recruitment are often thought to be positively related. However, environmental conditions generally fluctuate over time, which could lead to temporal changes in growth–recruitment relationships. Here, we investigate whether growth–recruitment relationships are time-varying by applying dynamic linear models, which allow coefficients to vary over time, to a 23-yr data set of recruitment and early life-stage growth rate in Japanese sardine Sardinops melanostictus. We found that the impact of growth rate on recruitment (i.e., the slope coefficient) was relatively high during the late 1990s, then gradually weakened, and has remained low in recent years. The baseline recruitment level (i.e., the intercept) also shifted over time, being relatively low in the late 1990s, gradually increasing, and remaining high in recent years. Furthermore, a model with time-varying intercept and slope was more statistically plausible than models with constant coefficients. These results indicate that the growth–recruitment relationship varied dynamically over time. Our findings highlight the need to consider the possibility of time-varying growth–recruitment relationships when investigating such relationships and predicting recruitment. [ABSTRACT FROM AUTHOR]

• Two Moraceae members constituted 94% of the wall-tree stock in Chongqing. • Most herbs on the walls were wind-dispersed while trees were bird-dispersed. • Masonry wall plant communities are different to surrounding ground communities. • Masonry walls in Chongqing are refugia of disturbance-intolerant native plants. • Wall species displayed a wide range of mortality ratios and fit a sieve model. Urbanization imposes notable threats to global biodiversity. Masonry retaining and city walls offer unusual ruderal habitats for spontaneous establishment of unique plant communities which may flourish despite urban disturbance and intensification. We comprehensively surveyed the wall-plant communities in Chongqing in southwest China to investigate their special urban ecology and their role in sustaining urban biodiversity. From 289 masonry walls, we recorded 205 plant species under 164 genera and 78 families. Perennial and annual herbs were the most common growth forms by species number. Despite accommodating 27 tree species and 6538 tree individuals, three dominant ones, respectively two Moraceae members Ficus virens which is a strangler fig and Broussonetia papyrifera , and Robinia pseudoacacia (Leguminosae), constituted 94% of the wall-tree stock. Detailed analysis of tree height distribution shed light on species recruitment dynamics. The dispersal agents differentiated sharply by growth form, with 73% herbaceous species wind-dispersed in comparison with 70.2% woody species bird-dispersed. The endemism and floristic characteristics of wall-plant communities were influenced by the regional urban flora, particularly for dominant wall trees; similar traits were found in the wall flora of Nanjing and Hong Kong. The low similarity in species composition between walls and nearby ground plant communities suggested the critical role played by walls in protecting the disturbance-intolerant native plants, including many Pteridophytes. The conservation values and biodiversity contributions of masonry walls in Chongqing are worthy of special attention. The findings could provide the basis to maintain urban ecosystem services and for nature-based ecological urban designs. [ABSTRACT FROM AUTHOR]

Savanna sites are idealized as exhibiting a demographic "bottleneck" physiognomy comprising a lower stratum of abundant resprouting persistent "juveniles" (albeit of indeterminate age), a mid‐stratum comprising relatively few released "saplings," and a canopy‐layer cohort of "adults." The magnitude and frequency of disturbance is considered to influence the critical transition from juvenile into adult phases. Under fire‐prone Australian savanna conditions, an extensive suite of both observational and manipulative studies have explored the responses of tree recruitment to fire disturbances. These studies oftentimes have produced seemingly highly disparate responses, particularly with respect to the differential responses of relatively fast‐growing eucalypts versus non‐eucalypts under different fire regime, and overstory competition, conditions. This study contrasts the responses of tree recruitment height classes to (1) the effects of total canopy removal from severe Cyclone Monica in 2006 over a subsequent 10‐yr period, (2) with observations from long‐term monitoring sites under relatively stable overstory conditions at Litchfield National Park over a six‐year period, (3) under ambient, frequent fire occurrence (mean > 0.5 fires/yr) at both locales including relatively severe late dry season fires. Recruitment at both study sites was represented mostly by resprouting, clonally reproducing juvenile trees <2 m tall, around half of which died over respective assessment periods. At post‐cyclone assessment plots, there was substantial release of eucalypts, including within the first five years, into the >5 m height class, with negligible corresponding release of non‐eucalypts. At Litchfield plots, there was negligible release of both eucalypts and non‐eucalypts. In discussion, we contrast these results with findings from relevant regional studies. We contend that collective disparate observations feasibly can be reconciled as reflecting significant interactions between fire regime characteristics and variable site overstory competition effects, such that the rate of recruitment of fast‐growing savanna eucalypt individuals into the midstory is relatively independent of the fire regime, but is significantly regulated by resource competition interactions especially with the overstory, whereas recruitment of non‐eucalypts is relatively independent of overstory competitive effects, but is suppressed under fire regimes dominated by frequent, especially severe fires. [ABSTRACT FROM AUTHOR]