Olfactory Ability Research Articles

Screening for Age-Related Olfactory Decline Using a Card-Type Odor Identification Test Designed for Use with Japanese People

A card-type odor identification test called the “Open Essence (OE),” consisting of 12 types of everyday odors familiar to Japanese people, was recently developed. In this study, we calculated the cut-off value of the OE score for screening for age-related olfactory decline. Participants aged 23 to 91 performed the OE test. After we confirmed that the OE score differed significantly between young/middle-aged adults (under 65 years old) and elderly adults (over 65 years old), we assumed that the young/middle-aged group had normal olfactory ability, whereas the elderly group had experienced a decline in odor identification ability. We then performed receiver operating characteristic (ROC) analysis using the OE score. The cut-off value of the OE score for screening for age-related olfactory decline, calculated on the basis of the ROC curve, was 8. Individuals with the OE scores of 7 or less may have age-related olfactory decline. Our finding suggests that this cut-off value could be used to screen Japanese people with age-related olfactory decline. The OE test is self-administered and has a cut-off value of the OE score for screening for age-related olfactory decline. Therefore, it is expected to be useful in mass screening for elderly adults.

Effectiveness of micronized nasal irrigations with hyaluronic acid/isotonic saline solution in non-polipoid chronic rhinosinusitis: A prospective, randomized, double-blind, controlled study.

Sodium hyaluronate has been proposed as a treatment for improving the symptoms of chronic rhinosinusitis. The present study evaluated the effect of the intranasal administration of hyaluronic acid in a group of patients affected by chronic rhinosinusitis without nasal polyps (CRSsNP). Thirty subjects aged 18-65years affected by CRSsNP were enrolled. The subjects were randomly administered hyaluronic acid or isotonic saline solution by nasal nebulizer twice per day for 30days. They were evaluated before (T0) and after the treatment (T1) with Sino-Nasal Outcome Test-22, visual analogue scale for rhinorrhea, nasal obstruction, facial pain and hyposmia/hypogeusia, nasal endoscopy, active anterior rhinomanometry, peak nasal inspiratory flow and nasal cytology. Comparing the study and the control group, at T1 no significant differences were observed in both objective and subjective parameters. Being included in the study group rather than in the control group did not have a significant effect on the variation of the considered parameters between T0 and T1. Considering the effects of the micronized douches independently from the type of solution used (either hyaluronic acid or isotonic saline solution), although no difference emerged between study and control group for any of the objective parameters, there was an improvement of Sino-Nasal Outcome Test-22 scores (p=.0005), visual analogue scale for nasal obstruction (p=.0006) and for hyposmia/hypogeusia (p=.04). The treatment with micronized nasal douches can improve the sino-nasal symptoms of CRSsNP, in particular nasal obstruction and olfactory ability. No advantage of the use of hyaluronic acid over isotonic saline solution emerged.

Alterations of the Motor and Olfactory Functions Related to Parkinson's Disease in Transgenic Mice With a VMAT2-Deficiency in Dopaminergic Neurons.

Parkinson’s disease (PD) is one of the most common neurodegenerative diseases, with approximately six million people affected worldwide. Vesicular monoamine transporter 2 (VMAT2) dysfunction has recently become a hot topic in the pathophysiology of PD, and the advent of transgenic mice has also accelerated the development of behavioral studies in animal models. However, there are only a few systematic behavioral tests that embrace abundant motor and non-motor performance in a unique mutant mouse model which correspond to the varied symptoms observed in human PD. The aim of this study is to evaluate the responsibility of the unique reduction of dopamine in the varied motor and non-motor symptoms of PD via a transgenic mice model. We analyzed neurotransmitter concentrations in the brain tissue of 18-month-old mutant mice, with selective inactivation of one allele of Vmat2 in dopaminergic neurons (VMAT2DATcre-HET) to confirm the selective reduction of dopamine, and then examined behavioral functions. Neurochemical tests showed lower dopamine concentrations in specific brain regions of VMAT2DATcre-HET mice, especially the ventral tegmental area/substantia nigra and striatum, together with relatively unchanging concentrations of norepinephrine and serotonin, demonstrating the dopaminergic specificity of this mouse model. Behavioral tasks showed impairments in several motor functions and major defects in olfactory abilities in the VMAT2DATcre-HET mice. However, no significant changes were found in the majority of non-motor tests, such as emotional performance and sleep patterns. We concluded from this study that the selective inactivation of one allele of the Vmat2 gene in dopaminergic neurons was related to dopamine reduction, resulting in phenotypes resembling some of the major deficits in PD, especially those of motor symptoms and olfactory functions.

Impaired olfactory ability associated with larger left hippocampus and rectus volumes at earliest stages of schizophrenia: A sign of neuroinflammation?

Impaired olfactory identification has been reported as a first sign of schizophrenia during the earliest stages of illness, including before illness onset. The aim of this study was to examine the relationship between volumes of these regions (amygdala, hippocampus, gyrus rectus and orbitofrontal cortex) and olfactory ability in three groups of participants: healthy control participants (Ctls), patients with first-episode schizophrenia (FE-Scz) and chronic schizophrenia patients (Scz). Exploratory analyses were performed in a sample of individuals at ultra-high risk (UHR) for psychosis in a co-submission paper (Masaoka et al., 2020). The relationship to brain structural measures was not apparent prior to psychosis onset, but was only evident following illness onset, with a different pattern of relationships apparent across illness stages (FE-Scz vs Scz). Path analysis found that lower olfactory ability was related to larger volumes of the left hippocampus and gyrus rectus in the FE-Scz group. We speculate that larger hippocampus and rectus in early schizophrenia are indicative of swelling, potentially caused by an active neurochemical or immunological process, such as inflammation or neurotoxicity, which is associated with impaired olfactory ability. The volumetric decreases in the chronic stage of Scz may be due to degeneration resulting from an active immune process and its resolution.

Excitability of Neural Activity is Enhanced, but Neural Discrimination of Odors is Slightly Decreased, in the Olfactory Bulb of Fasted Mice.

Olfaction and satiety status influence each other: cues from the olfactory system modulate eating behavior, and satiety affects olfactory abilities. However, the neural mechanisms governing the interactions between olfaction and satiety are unknown. Here, we investigate how an animal’s nutritional state modulates neural activity and odor representation in the mitral/tufted cells of the olfactory bulb, a key olfactory center that plays important roles in odor processing and representation. At the single-cell level, we found that the spontaneous firing rate of mitral/tufted cells and the number of cells showing an excitatory response both increased when mice were in a fasted state. However, the neural discrimination of odors slightly decreased. Although ongoing baseline and odor-evoked beta oscillations in the local field potential in the olfactory bulb were unchanged with fasting, the amplitude of odor-evoked gamma oscillations significantly decreased in a fasted state. These neural changes in the olfactory bulb were independent of the sniffing pattern, since both sniffing frequency and mean inhalation duration did not change with fasting. These results provide new information toward understanding the neural circuit mechanisms by which olfaction is modulated by nutritional status.

EARLY DETECTION AND TREATMENT OF AGE-RELATED COGNITIVE DECLINE

Jennifer Gatchel (Symposium Co-chair) will introduce the speakers and then present data from the Harvard Aging Brain Study and screening data from the Anti-Amyloid Treatment in Asymptomatic Alzheimer's Disease (A4) Study. Mood, cognition, and PET data from 4,486 participants will be presented from the A4 Study and from 135 participants from the Harvard Aging Brain Study. These unpublished data show associations among neuropsychiatric symptoms, cognition, and in vivo neuroimaging biomarkers—amyloid and tau—in cognitively unimpaired individuals. Findings support cortical amyloid and regional cerebral tau as risk factors for cognitive decline in older adults. Davangere Devanand will review the evidence that olfactory identification deficits predict the development of Alzheimer's dementia, and show that olfactory impairments are superior to episodic verbal memory deficits in predicting cognitive decline. He will present data from a large community sample showing that intact performance on brief global cognitive and olfactory tests is associated with lack of transition to dementia during follow-up. These unique data will show that in 711 subjects, intact olfactory and cognitive abilities were protective with few transitions to dementia and none in the 70-75 and 81-83 years age groups. Terry Goldberg will review the apolipoprotein E e4 allele (APOE e4) as a risk factor for Alzheimer's dementia, and present unpublished data from the National Alzheimer's Consortium database showing that the apolipoprotein E e2 (APOE e2) genotype is protective against amyloid and tau pathologies of Alzheimer's disease but not Lewy body pathology, fronto-temporal or related tauopathy dementias as identified by gold standard neuropathological diagnosis. He will describe unpublished genetic and pathologic results from the Alzheimer's NACC consortium (N=1557) showing that APOE e2 protects against Alzheimer's and APOE e4 promotes Lewy body pathology in limbic and cortical regions but not midbrain. Gary Small (Symposium Chair) will moderate the audience questions and panel responses after presenting new data from randomized controlled trials indicating the cognitive benefits of pomegranate juice, bioavailable curcumin, or physical exercise – all strategies that reduce inflammation. These findings, as well as previous research on medications, physical activity, diet, obesity, and other risk/protective factors, suggest that several anti-inflammatory interventions may protect brain health and lower the risk for Alzheimer's dementia. He will describe data from placebo-controlled trials of memory effects of pomegranate juice (N=260) and curcumin (N=40), and a trial of memory training/aerobic exercise (N=55).

Field-testing olfactory ability to understand human olfactory ecology.

We know little about human olfactory ability in natural settings because current knowledge derives from lab-based studies using nonrepresentative samples of convenience. The primary objective was to use a validated lab tool, the five-item odor identification test, to assess variation in olfactory ability in different environments. Using the five-item test, we conducted two repeated measures experiments that assessed participant ability to correctly identify an odor source in different odor environments. We also examined consistency in odor labelling due to documented potential bias from idiosyncrasies in odor terms. We found no variation in olfactory ability due to environment, but this may be due to methodological biases. First, subjective bias results from idiosyncratic differences in participant labelling and researcher coding of answer correctness. Second, better ability to learn odors may provide an advantage to women. Third, reducing positive female learning bias by analyzing consistency in response (regardless of correct odor source identification) results in no sex differences but fails to assess the functional aspect of olfactory ability (naming the correct odor source). Fourth, functional olfactory ability is significantly better in women, especially in food-rich odor environments. Environment was not a significant factor in olfactory ability in this study but that result may be confounded by methodological biases. We do not recommend odor identification as a field tool. Functional olfactory ability exhibits a sex-based pattern but consistency in recognizing the same odor does not. Food-rich odors may enhance olfactory ability in females. We discuss evolutionary and ecological implications of superior female functional olfactory ability relative to food foraging activity.

Retronasal olfactory testing using candies sent by post and for screening purposes: a feasibility study.

The olfactory system is able to detect external odours through the orthonasal- and internal odours through the retronasal route. Flavour perception strongly relies on the sense of smell and this back route. In contrast to orthonasal, retronasal olfactory tests (ROT) are less frequently applied, although testing should be recommended for several reasons. The aim of the present investigation was to propose a suitable form of ROT for home-testing (and postal distribution) and evaluate a retronasal screening test. Initially, 111 participants were tested using a 27-item version of the Candy Smell Test (CST). Fifty-four participants performed retesting, of which 25 subjects did so in a home-setting being supplied with professionally packed "candy-chains". Seven candies were chosen by means of hit rate differences in normosmics and severely hyposmics/anosmics. The 7-CST is designed in a non-forced-choice fashion with same seven flavours to choose from. For the 27-item CST both groups (subjects performing home-testing and those performing retesting at the clinic) showed highly significant test-rest-reliabilities. The 7-CST was capable of discriminating healthy from diseased subjects when being tested in 116 healthy subjects and 47 patients suffering from olfactory dysfunction. The CST is suitable for home-testing and postal distribution. The new 7-item CST can be valuable for rapidly revealing anosmics. These findings help in further standardizing ROT, may encourage rhinologists to more routinely evaluate retronasal olfactory abilities and pave the way for larger epidemiologic studies also in regard to food preferences and nutritional behaviour.

Examination of the influence of cedar fragrance on cognitive function and behavioral and psychological symptoms of dementia in Alzheimer type dementia.

We examined whether symptoms of dementia are improved by olfactory nerve stimulation in Alzheimer type dementia patients. First, a stick‐type olfactory identification ability test was performed in patients with Alzheimer type dementia, to select patients without olfactory dysfunctions. Then, these patients were randomly assigned into the intervention (n = 19) and the control groups (n = 17). To evaluate the effects of olfactory nerve stimulation, we exposed the intervention group to a disinfecting ethanol with added aroma extracts from ceder and the control group to the ethanol without the added aroma extracts. Each group underwent the intervention for 8 weeks, cognitive and behavioral functions were evaluated before and after treatments using the Neuropsychiatric Inventory (NPI), the Japanese version of Zarit Caregiver Burden interview (J‐ZBI), and the Alzheimer's Disease Assessment Scale‐cognitive subscale (ADAS‐cog). A significant improvement was observed in the NPI score and J‐ZBI in the intervention group compared to the control group at 4 and 8 weeks. On the other hand, there was no significant difference in the score of ADAS‐cog. Exposure to cedar fragrance improved behavioral and psychological symptoms of dementia (BPSD) in Alzheimer type dementia and may reduce the burden of nursing care. In addition to its effectiveness, the procedure is simple and minimally invasive and would be a valuable non‐pharmaceutical treatment.

Association between human olfactory performance and ability to detect single compounds in complex chemical mixtures.

Humans can accurately discern thousands of odorants, although there is a considerable inter-individual variability. Individuals can be classified as normosmic, hyposmic or anosmic, depending on their olfactory sensitivity or blindness. In this research we studied the olfactory sensitivity to banana head-space as a complex odor mixture in a group of 53 subjects classified for their olfactory status, by means of the "Sniffin' Sticks" extended test. Using the coupled Gas Chromatography-Mass Spectrometry/ Olfactometry (GC–MS/O) technique, the single components of the banana flavor mixture were separated, identified and verbally evaluated by each subject. For each compound both the “odor type” (i.e., odor quality: fruity, floral, green, etc.) and “odor descriptor” (i.e., name used by subjects for odor identification) were reported, so that we could identify molecules that were defined as smelling of banana. The results show that: (a) the threshold olfactory performance is linearly correlated with the number of odor-active compounds (total or smelling of banana) for each subject; (b) the intensity reported by each subject during the sniffing of the pen containing the banana aroma in the identification test is positively correlated both with its hedonic valence and the number of odor-active compounds smelling of banana. In conclusion, our findings show that human perception of single compounds is conditioned by the threshold olfactory performance of the subject and that his/her ability to detect single molecular components, which smell as the mixture, affects the intensity and hedonism for the complex aroma.

Exploring the Relationship Between Psychopathy and Taste Perception

Higher psychopathic traits have been consistently associated with poorer olfactory abilities; however, only one study as reported by Sagioglou and Greitemeyer (Appetite 96:299-308, 2016) has explored whether psychopathy is linked to taste perception. Using self-report measures, Sagioglou and Greitemeyer (2016) found higher psychopathic traits were associated with higher liking ratings for bitter stimuli. The aim of the current study was to determine whether direct assessment of taste perception was linked with psychopathic traits. Seventy-eight participants (41 females) rated four tastants (i.e. bitter, sweet, salty and sour), at four concentrations. For each of the 16 stimuli, participants rated how much they liked, how disgusting and how intense they perceived each tastant. Contrary to previous findings, higher psychopathic traits were not associated with higher liking ratings for bitter stimuli, but instead associated with higher disgust ratings of bitter stimuli. Moreover, higher psychopathic traits were associated with higher taste intensity ratings, suggesting psychopathy may be associated with increased taste sensitivity. Higher degrees of psychopathic traits are associated with higher disgust ratings of bitter stimuli. The findings suggest that the chemical senses may be another confirmatory method for differentiating those with low and high psychopathic traits.

Lateralized Deficits in Motor, Sensory, and Olfactory Domains in Dementia.

There exist functional deficits in motor, sensory, and olfactory abilities in dementias. Measures of these deficits have been discussed as potential clinical markers. We measured the deficit of motor, sensory, and olfactory functions on both the left and right body side, to study potential body lateralizations. This IRB-approved study (N = 84) performed left/right clinical tests of gross motor (dynamometer test), sensory (Von Frey test), and olfactory (peppermint oil test) ability. The Mini-Mental Status Exam was administered to determine level of dementia; medical and laboratory data were collected. Sensory and olfactory deficits lateralized to the left side of the body, while motor deficits lateralized to the right side. We found clinical correlates of motor lateralization: female, depression, MMSE <15, and diabetes. While clinical correlates of sensory lateralization: use of psychotherapeutic agent, age ≥85, MMSE <15, and male. Lastly, clinical correlates of olfactory lateralization: age <85, number of medications >10, and male. These lateralized deficits in body function can act as early clinical markers for improved diagnosis and treatment. Future research should identify correlates and corresponding therapies to strengthen at-risk areas.

Olfactory Impairment in Obese Patients

Background: Recently published work and emerging research efforts have suggested that the olfactory system abilities is intimately affected by morbid obesity. Morbidly obese patients demonstrate altered olfactory acuity. High body mass index (BMI) appears to be associated with olfactory dysfunction. Increasing BMI may be a risk factor for olfactory loss or lack of olfactory recovery after an inciting event. Objective: This study aimed to discuss olfactory impairment in obese patients and to elucidate what role olfactory loss may play in diet and feeding habits of obese patients Conclusion: Our study presented a strong evidence for a causal relationship between changes in olfactory abilities of obese patients. There was altered olfactory acuityand cardiovascular, inflammatory, and cognitive declines. It was found that consumption of diets high in fat are found to cause nervous system dysfunction.

Sniffing out solutions to enhance conservation: How detection dogs can maximise research and management outcomes, through the example of koalas

In conservation, consistent and extensive under-funding has necessitated creative thinking to address conservation issues on a low budget, and innovations are burgeoning as a result. One example is the use of dogs that, thanks to their heightened olfactory abilities and bond with humans, are trained to detect odours of interest to conservationists. Conservation dogs have proven to repeatedly outperform alternative survey methods in terms of accuracy, efficiency and/or cost. They have now been used for the detection of endangered and invasive species, fauna and flora, direct and indirect (e.g. scat) targets, on land and at sea, across every continent and most taxa from fire ants to whales. Here, we emphasise the versatility of detection dogs through their multiple uses applied to one species, the koala Phascolarctos cinereus . We selected, trained, tested and deployed five dogs; two for koala habitat (koala scats), one for genetic sampling (fresh scats only), one for the koala itself and one for koala disease ( Chlamydia spp. ) detection. Dogs enabled both large-scale and fine-scale survey design, with 2370 surveys performed, and 1479 genetic samples collected to date. Detection dogs are subject to similar (although sometimes much lower) limitations in terms of survey biases (e.g. individual or environmental conditions) and, importantly, detection dog/handler teams need to be tested regularly for accuracy. Nonetheless, detection dogs can, and are, helping researchers and land managers to collect more robust datasets and better inform conservation decisions. Alliances with unexpected partners in conservation (such as with police forces), citizen science, and timeshare use of dogs might improve the democratisation of their use and enable conservation detection dogs to fulfil their astonishing potential.

Metal-containing Particulate Matter and Associated Reduced Olfactory Identification Ability in Children from an Area of High Atmospheric Exposure in Mexico City.

Air pollution has been linked to poor olfactory function in human adults. Among pollutants, particulate matter (PM) is especially relevant, as it may contain toxic metal ions that can reach the brain via olfactory pathways. Our purpose was to investigate the relation between atmospheric PM and olfactory identification performance in children. Using a validated method, we tested the olfactory identification performance of 120 children, 6-12 years old, from two locations in Mexico City: a focal group (n = 60) from a region with high PM levels and a control group of equal size and similar socioeconomic level from a region with markedly lower PM concentrations. Groups were matched for age and sex. Concentrations of manganese and lead in the hair of participants were determined as biomarkers of exposure. Daily outdoor PM levels were obtained from official records, and indoor PM levels were measured in the children's classrooms. Official records confirmed higher levels of outdoor PM in the focal region during the days of testing. We also found higher classroom PM concentrations at the focal site. Children from the focal site had on average significantly lower olfactory identification scores than controls, and hair analysis showed significantly higher levels of manganese for the focal children but no difference in lead. Children appear to be vulnerable to the effects of air pollution on olfactory identification performance, and metal-containing particles likely play a role in this. Olfactory tests provide a sensitive, noninvasive means to assess central nervous function in populations facing poor air quality.

Fully Printed Geranium-Inspired Encapsulated Arrays for Quantitative Odor Releasing.

Olfactory is an extremely fine way of perception. However, the process of smelling is prone to various interference factors. Further development to enhance the communication desires an odor-releasing strategy, which could quantitatively offer a variety of fragrances. Here, we report a fully printing strategy to heterogeneously integrate odor-containing materials and protective coating films. Inspired from the fragrance-containing drum structure on the geranium leaf, encapsulated arrays are fully printed on the flexible or rigid substrates with more than 20 spices. Quantitative concentrations of odor molecules can be released from the encapsulated arrays after scraping the protective poly(lactic-co-glycolic) acid (PLGA) shells. Importantly, various odor-based arrays are printed on the same flexible substrate, which permits selective releasing and arbitrary mixing of the spices. Effective odor-releasing properties of encapsulated arrays make them promising for food security and anticounterfeiting, investigating olfactory discrimination abilities, and strengthening olfactory communication.

Flowers of European pear release common and uncommon volatiles that can be detected by honey bee pollinators

Floral scents are important pollinator attractants, but there is limited knowledge about the importance of single components in plant–pollinator interactions. This especially is true in crop pollination systems. The aim of this study is to identify floral volatiles of several European pear cultivars (Pyrus communis L.), and to determine their potential in eliciting physiological responses in antennae of honey bees (Apis mellifera L.), the most important pollinators of pear. Volatiles were collected by dynamic headspace and analysed by (high resolution) gas chromatography coupled to mass spectrometry (GC/MS) and nuclear magnetic resonance spectroscopy. Antennal responses were investigated by GC coupled to electroantennographic detection (GC/EAD). We trapped in the mean 256 ng of scent per flower and hour (flower−1 h−1) from the different cultivars with either linalool + methyl benzoate or methyl 2-hydroxy-3-methylpentanoate as most abundant compounds. Of the 108 detected pear floral scent components, 17 were electrophysiologically active in honey bee antennae. Among these compounds were (E)-N-(2-methylbutyl)- and (E)-N-(3-methylbutyl)-1-(pyridin-3-yl)methanimine, which were not known from nature before to the best of our knowledge. Most other compounds identified as flower scent in pear are widespread compounds, known from flowers of various other species. Our results provide new insights in the floral volatile chemistry of an important insect-pollinated crop and show for the first time that honey bees have the olfactory ability to detect several pear floral volatiles. These data are an important basis for more detailed studies of the olfactory communication between honey bees and European pear flowers and might in the long term be used to manipulate the attractiveness of pear to obtain optimal fruit set.

Intact global cognitive and olfactory ability predicts lack of transition to dementia

IntroductionOdor identification deficits characterize Alzheimer's disease and other dementias. We examined if intact performance on brief cognitive and odor identification tests predicts lack of transition to dementia. MethodsIn an urban community, 1037 older adults without dementia completed the 40-item University of Pennsylvania Smell Identification Test, which includes the 12-item Brief Smell Identification Test (B-SIT). Data from 749 participants followed up for 4 years were analyzed. ResultsIn covariate-adjusted survival analyses, impairment on the Blessed Orientation Memory Concentration Test and B-SIT each predicted dementia (n = 109), primarily Alzheimer's disease (n = 101). Among participants with intact olfactory (B-SIT ≥ 11/12 correct) and cognitive (Blessed Orientation Memory Concentration Test ≤ 5/28 incorrect) ability, 3.4% (4/117) transitioned to dementia during follow-up with no transitions in the 70–75 and 81–83 years age group quartiles. DiscussionOdor identification testing adds value to global cognitive testing, and together can identify individuals who rarely transition to dementia, thereby avoiding unnecessary diagnostic investigation.

Back to the basics with conservation detection dogs: fundamentals for success

The use of detection dogs in conservation studies has expanded across species, conditions and habitats. However, it is incorrect to assume the potential associated with these surveys is automatically linked to the dog's sense of smell. Instead, an accurate detection dog rate is directly linked to many caveats in dog–handler training. Selecting a detection dog is directly linked to a clearly defined study design and must balance various factors, including: olfactory ability, physical structure, energy level, personality and social traits. Selection of training samples should ensure sufficient variation in target and nontarget species, independent of whether the goal is to locate evidence of the animal (e.g. scat, feather) or the physical animal. Just as not all dogs are appropriate, not all persons are suitable for this type of work, as the handler must be consistent and attentive to details with an incredible physical and mental endurance to sustain the time in the field. Testing in controlled and field situations can determine if the personalities of the dog and handler balance, with time needed for each to gain the ability to ‘read’ the other. Proper training for the dog and handler is essential, with special attention paid to the innate reactions of the latter. After training of the team is complete, testing trials should mimic field conditions. While there is no single model to becoming a handler in wildlife detection dog studies, incorporating these fundamental concepts with professional training can help optimize sample detection rate, minimize handler and dog frustration, and maximize overall success with this technique.

Modeling larval dispersal for the gilthead seabream in the northwestern Mediterranean Sea

To investigate dispersal and connectivity between spawning and lagoon nursery habitats of the gilthead seabream, Sparus aurata, in the Gulf of Lions (northwestern Mediterranean Sea), we modeled the potential transport of the species’ larvae between its supposed main spawning site in the region (the Planier Island) and two of its main local nursery areas (the coastal lagoons of Thau and Salses-Leucate). Passive larval drift simulations using a dispersal biophysical model showed a large variability in the possible trajectories from spawning to nursery areas and in the predicted ages for larvae arrival on the two nursery sites. The most common ages at arrival obtained in the simulations (20–60 days) are broadly consistent with previous modeling studies but contrast with the actual ages of the S. aurata post-larvae collected in 2016 and 2017 at time of the lagoon entrances (60–90 days, from otolith readings). The period between 25 and 70 days being critical for gilthead seabream larvae to acquire sufficient swimming, osmoregulatory, and olfactory abilities to enter coastal lagoons, we argue that ontogenic development plays a crucial role in the transport and local retention of S. aurata larvae in the studied region, explaining the discrepancy between simulation results and observed data.