Recruitment Of Populations Research Articles

Effects of Temperature and Food Concentration on the Population Recruitment of Acartia bifilosa (Copepoda, Calanoida): Implications for the Over-Summering Life History Strategy in Jiaozhou Bay

To obtain a clear understanding of the over-summering life history strategy of the dominant species A. bifilosa in the Jiaozhou Bay, the effects of high temperature and food concentration (represented by chlorophyll a, Chl a) simulating in situ summer conditions on the reproduction and post-embryonic development of A. bifilosa were studied. We found that the A. bifilosa population did not disappear from the seawater column in summer, and its abundance increased from June to July, and then sharply declined in August. Both temperature and food concentration had a significant influence on the reproduction of A. bifilosa. The results showed that 20 °C could not trigger the decline in population abundance and the resting egg strategy, and 28 °C was the upper threshold of A. bifilosa in the Jiaozhou Bay. Higher food concentration was essential for A. bifilosa to maintain population recruitment at a higher temperature. Nauplii could develop to adults in the higher-food-level treatments (10 and 15 μg/L Chl a). However, nauplii could not develop to copepodite at 28 °C with 5 μg/L Chl a. Neither temperature nor food concentration could induce resting eggs, and no resting eggs were detected in our study. A principal components analysis showed that temperature plays a more vital role than food concentration in determining the population recruitment of A. bifilosa. We suggest that A. bifilosa populations could sustain the high-temperature season independent of producing resting eggs in the Jiaozhou Bay, and implications for the over-summering life history strategy of A. bifilosa in the Jiaozhou Bay should be further discussed.

Effects of highland environments on clonal diversity in aquatic plants: An interspecific comparison study on the Qinghai-Tibetan Plateau.

Clonal reproduction is one of the most distinctive characteristics of plants and is common and diverse in aquatic macrophytes. The balance between sexual and asexual reproduction is affected by various conditions, especially adverse environments. However, we know little about clonal diversity of aquatic plants under suboptimal conditions, such as at high altitudes, and having this information would help us understand how environmental gradients influence patterns of clonal and genetic variation in freshwater species. The microsatellite data of four aquatic taxa in our previous studies were revisited to estimate clonal and genetic diversity on the Qinghai-Tibetan Plateau. Clonal diversity among different genetic groups was compared. Local environmental features were surveyed. Beta regressions were used to identify the environmental factors that significantly explained clonal diversity for relative taxon. The level of clonal diversity from high to low was Stuckenia filiformis > Hippuris vulgaris > Myriophyllum species > Ranunculus section Batrachium species. A positive correlation between clonal and genetic diversity was identified for all taxa, except H. vulgaris. Clonal diversity was affected by climate in S. filiformis and by the local environment in H. vulgaris. For Myriophyllum spp., low elevation and high sediment nutrition were significant for sexual recruitment. The environmental effects on clonal diversity were not significant in R. sect. Batrachium spp. Clonal diversity of aquatic plants is moderate to high and varies greatly in highlands. The effects of breeding systems and environmental factors on the patterns of clonal variation were identified. Elevational gradients, climates and local conditions play different roles in clonal diversity among relative taxon. Our results highlight the importance of sexual recruitment in alpine aquatic plant populations and the influence of environmental factors on the genetic patterns in freshwater species at local and regional scales.

Participant recruitment and retention from vulnerable populations in clinical trials is a matter of trust

Clinical research sites can struggle with recruiting and retaining vulnerable populations. Vulnerable research participants often have significant trauma histories making traditional approaches to recruitment and retention tenuous. Due to these difficulties, vulnerable populations are often intentionally excluded from clinical research due to the additional time and work involved. While it is important to provide protections for any participant that has decreased autonomy or increased susceptibility to coercion, it is equally important to assure that individuals in vulnerable populations have access to any clinical research that might pertain to them. In addition, the new trends in the drug development industry including early-stage development, risk-identification, preventative care, and disease spread modeling are likely to include health disparate patient populations that have increased probability of vulnerability. In this article we discuss the roots of many vulnerabilities and how to foster trust for more effective recruitment and retention of vulnerable populations.

Naphthenic acid fraction compounds reduce the reproductive success of wood frogs (Rana sylvatica) by affecting offspring viability

Understanding the toxicity of organic compounds in oil sands process-affected water (OSPW) is necessary to inform the development of environmental guidelines related to wastewater management in Canada's oil sands region. In the present study, we investigated the effects of naphthenic acid fraction compounds (NAFCs), one of the most toxic components of OSPW, on mating behaviour, fertility, and offspring viability in the wood frog (Rana sylvatica). Wild adult wood frogs were exposed separately from the opposite sex to 0, 5, or 10 mg/L of OSPW-derived NAFCs for 24 h and then combined in outdoor lake water mesocosms containing the same NAFC concentrations (n = 2 males and 1 female per mesocosm, n = 3 mesocosms per treatment). Mating events were recorded for 48 h and egg masses were measured to determine adult fertility. NAFC exposure had no significant effect on mating behaviour (probability of amplexus and oviposition, amplexus and oviposition latency, total duration of amplexus and number of amplectic events) or fertility (fertilization success and clutch size). Tadpoles (50 individuals per mesocosm at hatching, and 15 individuals per mesocosm from 42 d post-hatch) were reared in the same mesocosms under chronic NAFC exposure until metamorphic climax (61–85 d after hatching). Offspring exposed to 10 mg/L NAFCs during development were less likely to survive and complete metamorphosis, grew at a reduced rate, and displayed more frequent morphological abnormalities. These abnormalities included limb anomalies at metamorphosis, described for the first time after NAFC exposure. The results of this study suggest that NAFCs reduce wood frog reproductive success through declines in offspring viability and therefore raise the concern that exposure to NAFCs during reproduction and development may affect the recruitment of native amphibian populations in the oil sands region.

Enrollment patterns and site-level predictors of Black participant recruitment to a multisite randomized clinical trial (RCT) of endocrine therapy adherence support.

68 Background: Accrual of racial and ethnic minority patients (pts) to clinical trials has been an ongoing challenge in research. Barriers exist at many levels of engagement including trial availability, screening biases, strict enrollment criteria, and structural racism. Lack of trial diversity has led to less generalizable medical evidence, suboptimal data for toxicity and efficacy of cancer treatments, poorer outcomes and continued mistrust by communities of color in research processes that exclude or marginalize them. Site factors and study design strategies associated with successful recruitment of diverse study populations are understudied. Methods: Alliance A191901 is an RCT testing combinations of text and telephone support to promote endocrine therapy adherence among breast cancer survivors. It oversamples Black participants and those < 50 years at thresholds of 30% each. Administrative enrollment data was used to track and describe monthly accrual trajectory by race among the initial 50% of participants (n = 590) and to examine associations between % Black participants accrued and accruing site characteristics, including site type, geographic region, % Black population in the site’s zip code and volume of pts by race accrued to recent (2018-2019) Alliance trials, using χ2 tests. We also examined patterns of Black participant accrual before and after closure of the A191901 study to non-Black participants. Results: At 50% accrual, 124 sites had enrolled at least 1 participant. Among 590 participants, 9.7% were Black and 22.5% were < 50 years. Neither site type nor volume was associated with % Black participants recruited. Sites in the South recruited higher proportions of Blacks (19.0% vs 5.6% for Midwest, the lowest region, p < 0.001). Neighborhood racial composition was positively associated with accrual of Black participants (17.2% at sites from highest Black composition vs. 2.3% in lowest, p < 0.001). Recruitment trajectories of Black participants consistently lagged those of non-Black participants in the first half of the study; however, Black participants recruited per month numerically increased after the study reached target accrual of non-Blacks and closed to non-Black participants. Conclusions: Sites in neighborhoods and geographic regions with larger Black populations recruited higher proportions of Black participants, but site type and volume were not associated with recruitment of Black participants. Closure of non-Black study strata based on predetermined accrual targets may positively impact recruitment trajectories of Black participants, but further study is needed. Site selection based on neighborhood composition and geography may be an appropriate tool for increasing trial diversity. Support: UG1CA189823. Clinical trial information: NCT04379570.

Precision Medicine in Parkinson's Disease: From Genetic Risk Signals to Personalized Therapy.

Understanding the pathophysiology and genetic background of Parkinson’s disease (PD) increases the likelihood of developing effective disease-modifying therapeutic strategies. In particular, the discovery of genetic variants causing or increasing the risk for PD has contributed to refining the clinical, biological, and molecular classification of the disease and has offered new insights into sporadic forms. It is even more evident that specific genetic mutations can show different responses to pharmacological and device-aided therapies. To date, several agents acting on multiple PD-causing pathogenic pathways have been tested as disease-modifying strategies, with disappointing results. This may be caused by the recruitment of PD populations whose underlying molecular pathophysiology is heterogeneous. We believe that an effective model of personalized medicine must be prioritized in the near future. Here, we review the current therapeutic options under clinical and preclinical development for PD and discuss the key pending questions and challenges to face for successful clinical trials. Furthermore, we provide some insights into the role of genetics in guiding the decision-making process on symptomatic and device-aided therapies for PD in daily clinical practice.

National Blood Foundation 2021 Research and Development summit: Discovery, innovation, and challenges in advancing blood and biotherapies.

National Blood Foundation 2021 Research and Development summit: Discovery, innovation, and challenges in advancing blood and biotherapies.

Demographic and functional responses of kit foxes to changes in prey abundance

Many carnivores exhibit demographic and functional responses to changes in prey abundance. Demographic responses often include changes in population size, litter size, and recruitment of young into the adult population. Functional feeding responses are commonly reported for many carnivore species. We investigated demographic and functional responses of kit foxes ( Vulpes macrotis Merriam, 1888) to changes in prey abundance during 2010–2013 in western Utah, USA. Between 2010 and 2013, litter size averaged 3.9 (±1.4) pups/litter. Survival rates of kit fox pups were 0.07, 0.01, 0.46, and 0.16, respectively, and there was a correlation between pup survival rates and rodent abundance; leporid (family Leporidae Fischer, 1817) abundance did not influence pup survival. There was a functional response as occurrence of kangaroo rat in the diet closely followed changes in kangaroo rat abundance. The occurrence of rodents in kit fox diet followed declines in rodent abundance (excluding Dipodomys spp. Gray, 1841). Leporid consumption by kit foxes was not correlated to leporid density. Kit fox survival was dependent on rodent abundance and more specifically, kangaroo rats. Understanding which population parameters of kit foxes are influenced by prey is critical for the conservation of this native mesocarnivore.

Statistical population reconstruction of moose (Alces alces) in northeastern Minnesota using integrated population models.

Given recent and abrupt declines in the abundance of moose (Alces alces) throughout parts of Minnesota and elsewhere in North America, accurately estimating statewide population trends and demographic parameters is a high priority for their continued management and conservation. Statistical population reconstruction using integrated population models provides a flexible framework for combining information from multiple studies to produce robust estimates of population abundance, recruitment, and survival. We used this framework to combine aerial survey data and survival data from telemetry studies to recreate trends and demographics of moose in northeastern Minnesota, USA, from 2005 to 2020. Statistical population reconstruction confirmed the sharp decline in abundance from an estimated 7,841 (90% CI = 6,702-8,933) in 2009 to 3,386 (90% CI = 2,681-4,243) animals in 2013, but also indicated that abundance has remained relatively stable since then, except for a slight decline to 3,163 (90% CI = 2,403-3,718) in 2020. Subsequent stochastic projection of the population from 2021 to 2030 suggests that this modest decline will continue for the next 10 years. Both annual adult survival and per-capita recruitment (number of calves that survived to 1 year per adult female alive during the previous year) decreased substantially in years 2005 and 2019, from 0.902 (SE = 0.043) to 0.689 (SE = 0.061) and from 0.386 (SE = 0.030) to 0.303 (SE = 0.051), respectively. Sensitivity analysis revealed that moose abundance was more sensitive to fluctuations in adult survival than recruitment; thus, we conclude that the steep decline in 2013 was driven primarily by decreasing adult survival. Our analysis demonstrates the potential utility of using statistical population reconstruction to monitor moose population trends and to identify population declines more quickly. Future studies should focus on providing better estimates of per-capita recruitment, using pregnancy rates and calf survival, which can then be incorporated into reconstruction models to help improve estimates of population change through time.

Twelve-year changes in palm populations from a tropical lowland forest in the Philippines

Arecaceae (Palmae) is an ecologically and economically important family characteristic of the vegetation in tropical and subtropical regions, with at least 125 species occurring in the Philippines, most of them endemics. We monitored changes in stem density, mortality and recruitment of palm populations for 12 years within a 16-ha Forest Dynamic Plot located in northern Luzon, the Philippines. We recorded a total of 4060 stems, dominated by Pinanga insignis (46%) and P. maculata (34%), followed by Caryota cumingii (19%), and a few stems (< 1%) of Orania decipiens and Areca whitfordii. Half (51%) of the initially recorded stems in the 2004 census died by the time of the 2016 census, while 1086 (36%) additional stems were recorded in the same period. Overall palm population declined with the decreasing populations of P. insignis and P. maculata due to higher mortality than recruitment during the 2004–2010 and 2010–2016 census intervals while C. cumingii population increased in the same period. Regarding topographic position, the stem density of P. maculata is higher in valleys > midslopes > ridges across censuses, higher in valleys and midslopes than ridges for C. cumingii across censuses, and higher in midslopes than valleys for P. insignis during the 2016 census only. Mortality and recruitment were weakly observed along topographic positions between species and across censuses. Our result presents how palm population may change within 12 years with population trends differing between species, indicating the importance of palms in understanding the population dynamics of plant communities in a fast-changing environment.

Motor cortical influence relies on task-specific activity covariation.

During limb movement, spinal circuits facilitate the alternating activation of antagonistic flexor and extensor muscles. Yet antagonist cocontraction is often required to stabilize joints, like when loads are handled. Previous results suggest that these different muscle activation patterns are mediated by separate flexion- and extension-related motor cortical output populations, while others suggest recruitment of task-specific populations. To distinguish between hypotheses, we developed a paradigm in which mice toggle between forelimb tasks requiring antagonist alternation or cocontraction and measured activity in motor cortical layer 5b. Our results conform to neither hypothesis: consistent flexion- and extension-related activity is not observed across tasks, and no task-specific populations are observed. Instead, activity covariation among motor cortical neurons dramatically changes between tasks, thereby altering the relation between neural and muscle activity. This is also observed specifically for corticospinal neurons. Collectively, our findings indicate that motor cortex drives different muscle activation patterns via task-specific activity covariation.

Current status and perspective of tumor immunotherapy for head and neck squamous cell carcinoma.

Head and neck squamous cell carcinoma (HNSCC) have a high incidence and mortality rate, and investigating the pathogenesis and potential therapeutic strategies of HNSCC is required for further progress. Immunotherapy is a considerable therapeutic strategy for HNSCC due to its potential to produce a broad and long-lasting antitumor response. However, immune escape, which involves mechanisms including dyregulation of cytokines, perturbation of immune checkpoints, and recruitment of inhibitory cell populations, limit the efficacy of immunotherapy. Currently, multiple immunotherapy strategies for HNSCC have been exploited, including immune checkpoint inhibitors, costimulatory agonists, antigenic vaccines, oncolytic virus therapy, adoptive T cell transfer (ACT), and epidermal growth factor receptor (EGFR)-targeted therapy. Each of these strategies has unique advantages, and the appropriate application of these immunotherapies in HNSCC treatment has significant value for patients. Therefore, this review comprehensively summarizes the mechanisms of immune escape and the characteristics of different immunotherapy strategies in HNSCC to provide a foundation and consideration for the clinical treatment of HNSCC.

Factors influencing pregnancy, litter size, and reproductive parameters of invasive wild pigs

AbstractReproduction is the most energetically expensive life stage with the demands of productivity representing a balance between physiological requirements and environmental conditions. Wild pigs (Sus scrofa) throughout most of North America are genetic hybrids of feral domestic pigs and wild boar and have the highest reproductive potential of any wild ungulate. The phenology of reproduction, extent of multiple reproductive events per year, how individual and extrinsic factors contribute to variability in productivity, and impact of genetic lineage on these parameters is not well understood in wild pigs. We quantified reproductive parameters in wild pigs relative to a suite of individual and environmental attributes across seasons and multiple years in South Carolina, USA, from March 2017 and May 2020. We hypothesized that individual attributes (mass, age class, number of teats, rump fat, relative genetic association to wild boar vs. domestic pigs) and extrinsic factors (mast availability) would influence probability of pregnancy and fetal litter size. Wild pigs produced offspring throughout all months with peaks in conception corresponding to a seasonal pulse in food availability. The likelihood of pregnancy was influenced by female mass and nutritional condition and was greatest during years with abundant resources. Similarly, litter size increased with female mass and age, implying larger and older females represent the most important group for population recruitment. In evaluating the relationship between reproductive output and ancestral associations to domestic pigs versus wild boar, the proportion of wild boar ancestry was not an important influence on productivity in our population. We determined juveniles reach a physiological threshold of sexual maturity at approximately 30 kg. Average litter size was comparable to other populations, and wild pigs maintain an average fetal litter size of 5.43 offspring despite 13.6% embryonic mortality. A thorough understanding of biotic and extrinsic factors influencing reproduction are important for realistic population models, which are necessary for identifying areas to focus management needs and implementation.

Toxicity of perfluoroalkyl substances (PFAS) toward embryonic stages of mahi-mahi (Coryphaena hippurus).

Perfluoroalkyl substances (PFAS) are highly persistent organic pollutants that have been detected in a wide array of environmental matrices and, in turn, diverse biota including humans and wildlife wherein they have been associated with a multitude of toxic, and otherwise adverse effects, including ecosystem impacts. In the present study, we developed a toxicity assay for embryonic stages of mahi-mahi (Coryphaena hippurus), as an environmentally relevant pelagic fish species, and applied this assay to the evaluation of the toxicity of "legacy" and "next-generation" PFAS including, respectively, perfluorooctanoic acid (PFOA) and several perfluoroethercarboxylic acids (PFECA). Acute embryotoxicity, in the form of lethality, was measured for all five PFAS toward mahi-mahi embryos with median lethal concentrations (LC50) in the micromolar range. Consistent with studies in other similar model systems, and specifically the zebrafish, embryotoxicity in mahi-mahi generally (1) correlated with fluoroalkyl/fluoroether chain length and hydrophobicity, i.e., log P, of PFAS, and thus, aligned with a role of uptake in the relative toxicity; and (2) increased with continuous exposure, suggesting a possible role of development stage specifically including a contribution of hatching (and loss of protective chorion) and/or differentiation of target systems (e.g., liver). Compared to prior studies in the zebrafish embryo model, mahi-mahi was significantly more sensitive to PFAS which may be related to differences in either exposure conditions (e.g., salinity) and uptake, or possibly differential susceptibility of relevant targets, for the two species. Moreover, when considered in the context of the previously reported concentration of PFAS within upper sea surface layers, and co-localization of buoyant eggs (i.e., embryos) and other early development stages (i.e., larvae, juveniles) of pelagic fish species to the sea surface, the observed toxicity potentially aligns with environmentally relevant concentrations in these marine systems. Thus, impacts on ecosystems including, in particular, population recruitment are a possibility. The present study is the first to demonstrate embryotoxicity of PFAS in a pelagic marine fish species, and suggests that mahi-mahi represents a potentially informative, and moreover, environmentally relevant, ecotoxicological model for PFAS in marine systems.

Reproductive biology of the bullseye puffer Sphoeroides annulatus: Gonadosomatic index and its suitability for estimating length at maturity.

This study aimed to describe updated information on the basic reproductive biology of Sphoeroides annulatus females and potential use of the gonadosomatic index as input data to assess length at 50% maturity ( ) and identify the breeding season. From April 2014 to December 2015, 767 females were analysed along the north-west coast of the Mexican Pacific Ocean. Both immature and mature females were represented in the total length ( ), which ranged from 81 to 440 mm, and the smallest mature female was 92 mm (new record for the species). Gonadal maturity phases were assigned through histological analysis. A threshold value was established using the lower whisker value for maturity phase spawning capable (2.06%). The monthly variation of supported the annual spawning seasonality, and the presence of reproductively active mature females coincided with the observed periods with histological data and the peaks for both seasons 2014 and 2015. Also the presence of reproductively inactive mature females confirmed the nonreproductive season observed from January to April 2015. Estimates of were based on the cumulative proportion of reproductively active mature females: both datasets showed a 'bumpy trajectory'. Considering the functional form of data and models, a second objective was to verify if each dataset presented a simple or double sigmoid trajectory and select the most suitable model through the Akaike information criterion. For both datasets, the best fitted model was the double sigmoidal , while the single sigmoidal had low performance and did not have statistical support. The provided a value ca. 254 mm for both data sets. A trade-off between the model's correct fit and a reliable value was found, but this fact is not always considered when calculating the maturity, resulting in biased parameters. Correct data fitting may seem trivial, but the consequences for the conservation of immature individuals could be dramatic, affecting the population recruitment. In conclusion, the histologically calibrated was suitable for classifying females of S. annulatus into reproductively inactive or active types, with an agreement percentage of 99%. The =2.06% can be useful for subsequent studies for this species.

Public knowledge and information sources for clinical trials among adults in the USA: evidence from a Health Information National Trends Survey in 2020

Lack of clinical trial awareness has been identified as a barrier to clinical trial recruitment. Identifying factors associated with clinical trial knowledge could inform ongoing efforts to improve diversity in clinical trials. Using data from the Health Information National Trends Survey, 2020, we examined the knowledge of clinical trials, associated characteristics, sources of clinical trial information and motives to participate in clinical trials among the general population in the USA. Of 3,772 US adults, 41.3% reported not knowing about clinical trials. Prevalence of having no knowledge of clinical trials was higher among Hispanic adults (51.8%) and non-Hispanic Black adults (41.8%) compared with non-Hispanic White adults (37.4%; p=0.013). Other significant predictors of knowledge about clinical trials included higher education, online health information-seeking behaviour and patient portal access. Most respondents (73.2%) reported that healthcare providers were the most trusted source of information. Helping other people (71.6%) was the primary motivation for clinical trial participation, followed by financial compensation (12.5%) and receiving better treatment (5.1%). There is a gap in knowledge about clinical trials among the US population. Development of multimodal approaches, including online and offline information broadcasting, is needed to improve knowledge and clinical trial recruitment in diverse populations.

Impact of the use of different temperature‐dependent larval development functions on estimates of potential large‐scale connectivity of American lobster

AbstractThe way in which the effect of temperature on the development rate of crustacean larvae is simulated in larval dispersal models potentially impacts the inferences made about population recruitment and connectivity. In this study, we contrasted dispersal and connectivity predictions made by a large‐scale dispersal model of American lobster (Homarus americanus H. Milne Edwards, 1837) larvae using three temperature‐dependent larval development functions proposed in the literature: (1) “warm‐source lab”, (2) “warm‐source field”, and (3) “cold‐source lab”. Differences in predictions using each function were contrasted in the northern (colder) and southern (warmer) portions of the species' range. Using these different development functions resulted in significant and marked differences (61.3–162.4 km in the north and 30.9–81.9 km in the south) in the distances dispersed by larvae from hatch to settlement. In general, predicted self‐seeding, retention, and local connectivity were increased, and predicted connectivity among distant locations was decreased, when a function predicting faster development was used. The field‐derived function predicted much less connectivity and decreased dispersal overall than both lab‐derived functions. The cold‐source lab function predicted more retention in northern regions, but less in southern regions, than the warm‐source lab function. Our findings indicate the need for more studies to quantify the rate at which lobster larvae develop in nature, including how this may vary over space and time.

Interferon-γ resistance and immune evasion in glioma develop via Notch-regulated co-evolution of malignant and immune cells.

Immune surveillance is critical to prevent tumorigenesis. Gliomas evade immune attack, but the underlying mechanisms remain poorly understood. We show that glioma cells can sustain growth independent of immune system constraint by reducing Notch signaling. Loss of Notch activity in a mouse model of glioma impairs MHC-I and cytokine expression and curtails the recruitment of anti-tumor immune cell populations in favor of immunosuppressive tumor-associated microglia/macrophages (TAMs). Depletion of Tcells simulates Notch inhibition and facilitates tumor initiation. Furthermore, Notch-depleted glioma cells acquire resistance to interferon-γ and TAMs re-educating therapy. Decreased interferon response and cytokine expression by human and mouse glioma cells correlate with low Notch activity. These effects are paralleled byupregulation of oncogenes anddownregulation of quiescence genes. Hence, suppression of Notch signaling enables gliomas to evade immune surveillance and increases aggressiveness. Our findings provide insights into how brain tumor cells shape their microenvironment to evade immune niche control.

Orchid fruiting success is unrelated to surrounding floral resources in South Australian plant communities

AbstractTo maintain recruitment in orchid populations in an ecosystem setting, we must understand how surrounding floral resources affect fruiting success. We studied fruiting success in two endemic Australian species, Diuris pardina and Glossodia major, in relation to surrounding floral resources. Diuris pardina has a visually deceptive pollination strategy via mimicry of pea flowers, attracting pollinators associated with co-flowering plants of Pultenaea. Glossodia major displays dummy anthers and has a more generalist pollination strategy. We expected fruiting success of both species to positively correlate to conspecific and heterospecific floral density because orchid pollination should be enhanced by the attraction of higher densities of native bees. We expected fruiting success of D. pardina to positively correlate with abundance of Pultenaea flowers. Surveying 18 plots in South Australia, we counted species, individuals and flowers of conspecifics and heterospecifics and returned to count flowers that set fruit. We conducted Pearson correlations between fruiting success and density of conspecific flowers, richness, abundance and Shannon index of surrounding floral resources and floral abundance of individual species. Fruiting success was correlated with conspecific floral density for D. pardina but not G. major. No relationship was found between fruiting success and heterospecific floral resources. Fruiting success of D. pardina was not correlated with abundance of Pultenaea; instead it was positively correlated with the invasive species Lavandula stoechas.

Long-Term Monitoring of In-Water Abundance of Juvenile Pelagic Loggerhead Sea Turtles (Caretta caretta): Population Trends in Relation to North Atlantic Oscillation and Nesting

Sea turtles have various life-stages, typically being oceanic foragers as juveniles while shifting to more coastal habitats as they mature. The present study focuses on the least studied and well known of these, the juvenile oceanic life stage for the loggerhead sea turtle, Caretta caretta. Loggerhead sea turtles remain threatened by fisheries and their distribution and habitat change in the North Atlantic remains poorly understood. After hatching and swimming out to sea, turtles spend 7 or more years in the pelagic life stage. Madeira Island has an advantage of being situated in the middle of the North Atlantic developmental habitat for loggerheads originating both from the US, as well as, from Cape Verde and other mixed source rookeries. Understanding the demographics of this oceanic life stage has been described as a research priority. We here present a population trendline and the abundance variation of oceanic stage loggerheads, measured at a single geographic spot in Madeiran waters, over the period of 15 years. We find that the observed loggerhead distribution results from combined effects of physical and biological processes within the North Atlantic. We explore physical phenomena that influence abundance variability, and find that oscillations in climate affect the turtle migrations, as does the population recruitment from the nesting rookeries. For this, we use novel cost-effective census methods that take advantage of platforms of opportunity from the blue ecotourism industry. To study the time series and their correlations we use spectral analysis, a method not commonly used in traditional population assessments, including Wavelet and Fourier Transformations (WT and FFT), and Digital Signal Processing (DSP) techniques. A strong anti-correlation between sea turtle sightings and North Atlantic Oscillation seasonal components was found, which implies that loggerhead sea turtles are less abundant during positive NAO phases. We also detected long period trends in the sighting data which we relate to La Niña and El Niño oscillations. Source rookeries also influenced the sighting data with a time-lag of ~ 7 years, which coincides with the average time that turtles spend as oceanic juveniles.