How foundation species shape tidal flats

In this thesis, I described how foundation species contribute to the of shape tidal flats based on a variety of species, regions and species interactions. Based on these results, I can conclude that both biological and physical processes play an important role in shaping tidal flats. For instance, the foundation species affect their environment strongly by sediment bioturbation or accretion. On the other hand, physical forces play an important role in the species distribution or the effect of foundation species on the environment i.e., when physical forces are too strong, foundation species will not survive or change their surroundings. To conclude, it is valuable to focus on an integral approach implementing both physical and biological processes when studying tidal flats. With this thesis, I took some important steps toward understanding tidal flat formation by studying small-scale species interactions and translate them to landscape-scale functioning

Mutual facilitation between foundation species Mytilus edulis and Lanice conchilega promotes habitat heterogeneity on tidal flats

Foundation species that modify their habitat can facilitate other species, including other foundation species. Most studies focus solely on a single foundation species, overlooking such facilitation cascades. In this study, we investigated the interactions between the two coastal foundation species Mytilus edulis (blue mussel) and Lanice conchilega (sand mason worm). We investigated whether these species engage in facilitative interactions or if their association simply reflects a shared ecological niche on the soft-sediment intertidal flats of the Dutch Wadden Sea. To do so, we performed species distribution modeling, manipulative field experiments, and field surveys. We found a positive association between both foundation species, with a 2.45 times higher occurrence of both species compared to a random distribution. In addition, these species partially occupied the same ecological niche. We demonstrated that L. conchilega provided settlement substrate for M. edulis spat, increasing densities by 400 times compared to bare plots. Furthermore, M. edulis reefs facilitated L. conchilega occurrence in the wake of the reef. Biogenic reef development revealed that this interspecific facilitation resulted in spatial habitat heterogeneity. Therefore, we conclude that interspecific facilitation can significantly enhance the occurrence of these two important intertidal foundation species. Acknowledgment of such complex facilitation interactions has an untapped potential for improving the success of restoration and conservation programs.</p

Genetic variation in the endocannabinoid system and response to cognitive behavioural therapy for child anxiety disorders

Extinction learning is an important mechanism in the successful psychological treatment of anxiety. Individual differences in response and relapse following Cognitive Behavior Therapy may in part be explained by variability in the ease with which fears are extinguished or the vulnerability of these fears to re-emerge. Given the role of the endocannabinoid system in fear extinction, this study investigates whether genetic variation in the endocannabinoid system explains individual differences in response to CBT. Children (N = 1,309) with a primary anxiety disorder diagnosis were recruited. We investigated the relationship between variation in the CNR1, CNR2, and FAAH genes and change in primary anxiety disorder severity between pre- and post-treatment and during the follow-up period in the full sample and a subset with fear-based anxiety disorder diagnoses. Change in symptom severity during active treatment was nominally associated (P < 0.05) with two SNPs. During the follow-up period, five SNPs were nominally associated with a poorer treatment response (rs806365 [CNR1]; rs2501431 [CNR2]; rs2070956 [CNR2]; rs7769940 [CNR1]; rs2209172 [FAAH]) and one with a more favorable response (rs6928813 [CNR1]). Within the fear-based subset, the effect of rs806365 survived multiple testing corrections (P < 0.0016). We found very limited evidence for an association between variants in endocannabinoid system genes and treatment response once multiple testing corrections were applied. Larger, more homogenous cohorts are needed to allow the identification of variants of small but statistically significant effect and to estimate effect sizes for these variants with greater precision in order to determine their potential clinical utility

Cross-habitat interactions in the Wadden Sea

Here, we report on the results of the OBN-project ‘Cross-habitat interactions in the Wadden Sea’. Evidence is mounting that ecological linkages between spatially separated key-habitats are vital for the functioning of these habitats. However, management of these habitats rarely considers such spatial interactions in their conservation or restoration approaches. The presented work was carried out in close collaboration with the project ‘Restoration of Griend’, and as such formed part of an integrated investigation into the importance of spatial connectivity between the island Griend and the surrounding mudflats for the restoration and conservation of this, and similar slands. The main goals were to (1) understand how spatial connectivity drives the functioning of the island and the surrounding habitats, and (2) provide recommendations regarding the integration of spatial connectivity into future management approaches

The utility of the SCAS-C/P to detect specific anxiety disorders among clinically anxious children

Questionnaire measures offer a time and cost-effective alternative to full diagnostic assessments for identifying and differentiating between potential anxiety disorders and are commonly used in clinical practice. Little is known, however, about the capacity of questionnaire measures to detect specific anxiety disorders in clinically anxious preadolescent children. This study aimed to establish the ability of the Spence Children’s Anxiety Scale (SCAS) subscales to identify children with specific anxiety disorders in a large clinic-referred sample (N = 1,438) of children aged 7 to 12 years. We examined the capacity of the Separation Anxiety, Social Phobia, Generalized Anxiety, and Physical Injury Fears (phobias) subscales to discriminate between children with and without the target disorder. We also identified optimal cutoff scores on subscales for accurate identification of children with the corresponding disorder, and examined the contribution of child, mother, and father reports. The Separation Anxiety subscale was able to accurately identify children with separation anxiety disorder, and this was replicated across all 3 reporters. Mother- and father-reported Social Phobia subscales also accurately identified children with social anxiety disorder, although child report was only able to accurately detect social anxiety disorder in girls. Using 2 or more reporters improved the sensitivity of the Separation Anxiety and Social Phobia subscales but reduced specificity. The Generalized Anxiety and Physical Injury Fears subscales failed to accurately identify children with the corresponding disorders. These findings have implications for the potential use of mother-, father-, and child-report SCAS subscales to detect specific disorders in preadolescent children in clinical settings

Initiating and upscaling mussel reef establishment with life cycle informed restoration:Successes and future challenges

Worldwide, coastal ecosystems are rapidly degrading in quality and extent. While novel restoration designs include facilitation to enhance restoration success in stressful environments, they typically focus on a single life-stage, even though many organisms go through multiple life-stages accompanied by different bottlenecks. A new approach – life cycle informed restoration – was designed to ameliorate multiple bottlenecks throughout an organism's life cycle. It has successfully been tested on a small scale to facilitate intertidal bivalve reef formation in the Netherlands and Florida. Yet, it remains unknown whether this approach can be scaled to ecosystem-relevant scales. To test whether life cycle informed restoration is upscalable, we conducted a large-scale restoration experiment using blue mussel reefs as a model system. In our experiment, we used biodegradable structures to temporarily facilitate mussel reef formation by providing early-life settlement substrates, and subsequently, reduce post-settlement predation on an intertidal flat in the Wadden Sea, the Netherlands. The structures were placed in 10 × 20 m plots, mimicking bands found in natural mussel beds, spread out across 650 m, and were followed for two years. Our results show that the structures enhance mussel biomass (0.7 ± 0.2 kg DW m−2), as mussels were absent in bare plots. However, biomass varied within plots; in intact structures it was 60 times higher (1.2 ± 0.2 kg DW m−2) than in those that became buried (0.02 ± 0.009 kg DW m−2). Next to burial, 18–46% of the structures were lost due to technical failure, especially during winters at this exposed site. We show that the life cycle informed restoration principle works, but we encountered technical challenges due to larger scale processes (e.g. sedimentation). Furthermore, environmental information is essential for site selection, and for restoration, the functioning of such structures should be tested under extreme conditions before upscaling

The impact of treatment delivery format on response to Cognitive Behaviour Therapy for pre-adolescent children with anxiety disorders

Background. Several delivery formats of Cognitive Behaviour Therapy (CBT) for child anxiety have been proposed, however there is little consensus on the optimal delivery format. The primary goal of this study was to investigate the impact of the child’s primary anxiety diagnosis on changes in clinical severity (of the primary problem) during individual CBT, group CBT, and guided parent-led CBT. The secondary goal was to investigate the impact of the child’s primary anxiety diagnosis on rates of remission for the three treatment formats. Methods. A sample of 1253 children (5 – 12 years; Mage = 9.3, SD = 1.7) was pooled from CBT trials carried out at 10 sites. Children had a primary diagnosis of Generalised Anxiety Disorder (GAD), Social Anxiety Disorder (SoAD), Specific Phobia (SP) or Separation Anxiety Disorder (SAD). Children and parents completed a semi-structured clinical interview to assess the presence and severity of DSM-IV psychiatric disorders at pre intervention, post intervention and follow-up. Linear mixture modelling was used to evaluate the primary research question and logistic modelling was used to investigate the secondary research question. Results. Children with a primary diagnosis of GAD, SoAD and SAD demonstrated comparable improvements in clinical severity to all three CBT treatment formats. However, children with primary SP showed significantly larger reductions in clinical severity following individual CBT compared to group CBT and guided parent-led CBT. The results were mirrored in the analysis of remission responses with the exception that individual CBT was no longer superior to group CBT for children with a primary SP. Furthermore, the difference between individual and group was not significant when the follow-up data was examined separately. Conclusions. The data show that there may be greater clinical benefit by allocating children with a primary SP to individual CBT, although future research on cost-effectiveness is needed to determine whether the additional clinical benefits justify the additional resources required