Spiders as indicators for habitat evaluation in the Flemish coastal dunes

During this lecture, we present the results of a detailed study on the occurrence and ecology of spiders in the Flemish coastal dunes, as a tool for evaluating the conservation importance of dune arthropod species in general. Spider diversity is evaluated in function of the different assemblages, which are habitat specific. Especially dune grasslands, dune slacks and Marram dunes represent the highest value for nature conservation because of the presence of dune characteristic and dune specific species. These habitats are now heavily fragmented because of grass- and scrub encroachment. This fragmentation results in decreasing habitat surfaces, which affect the diversity and assemblage stability negatively. Habitat fragmentation not only affects the species diversity, but can also influence the viability of population. Within this framework we present the results of research on the effects of grassland fragmentation on the population dynamics, genetics and viability of our model species Pardosa monticola. Our results indicate that arthropod (spider) conservation will not only depend on the conservation of suitable habitat but also on the general landscape configuration

Colour variation and crypsis in relation to habitat selection in the males of the crab spider <i>Xysticus sabulosus</i> (Hahn, 1832) (Araneae: Thomisidae)

The crab spider Xysticus sabulosus (HAHN, 1832) is a sit-and-wait predator, typical for sandy habitats in Europe and Flanders. In the Flemish coastal dunes, the species is very abundant in grey and blond dunes. lts abdominal and cephalothorical colour varies from almost completely white to dark brown. During autumn 2001, we investigated crypsis as a function ofthe occupied micro- and macrohabitat. Our results indicate that (1) Colouration differs between the populations. The species is darker in a grey dune completely covered with dried (brown) mosses and in a humid dune slack covered with algae, than in populations from a sea inlet and from a blond dune. The colouration of a population from a grey dune with mosses, lichens and bare sand is intermediate. (2) Individual cephalothoracal colouration is, in contrast to abdominal colouration, related to microhabitat selection: individuals with darker cephalothoraxes occupy hunting sites with a higher coverage of mosses, while those with a pale one are found in microhabitats with a high amount of nude sand. The observed spider colour-environment covariation between populations is probably the result of natural selection or colour alteration during the juvenile development. Further research on these possible underlying mechanisms remains, however, necessary

Life history, habitat use and dispersal of a dune wolf spider (<i>Pordosa monticola</i> (Clerck, 1757) Lycosidae, Araneae) in the Flemish coastal dunes (Belgium)

Pardosa monticola (Araneae, Lycosidae) is a rare spider in Flanders. It is restricted to thermophilic mesotrophic (dune and heath) grasslands. Its life cycle and its habitat preference in the coastal dunes were analysed by interpreting data of more than 200 year-round pitfall-samplings. Viable populations are found in short dune grasslands (grazed by rabbits) and in mown young dune slacks. The life cycle is mixed annual-biannual and hibernation takes place in the juvenile or sub-adult instars. In short grasslands, the species overwinters in the rough neighbouring vegetation, in dune slacks, in litter accumulations. In the latter, the species survives submerging during winter inundation. Dispersal between suitable habitats can occur by male terrestrial movements via xerophylic habitats and dense grassland vegetation. Aeronautic dispersal is a rare phenomenon in the first instars that takes place only in periods of food shortage. Although a low proportion of the population exhibits this behaviour, this kind of dispersal can be of great importance for gene exchange between distant or strongly isolated populations. The implications and the importance of these data are discussed in relation to contemporary nature management

Therevidae (Diptera) in the East-Flemish inland dunes, pioneers on sandy soils?

Relicts of East-Flemish inland dunes were investigated for the presence of dune-land fauna. Five of the 8 therevid species known from Flanders were found in the present study. In contrast to asilids, therevids showed to be pioneer species preferring areas with large bare sandy patches. Pit fall traps proved to be twice as effective to sample therevids than white or yellow pan traps. Yellow traps are ineffective. Highest activity and diversity is found in June and July

A Study For Efficiently Solving Optimisation Problems With An Increasing Number Of Design Variables

Coupling optimisation algorithms to Finite Element Methods (FEM) is a very promising way to achieve optimal metal forming processes. However, many optimisation algorithms exist and it is not clear which of these algorithms to use. This paper investigates the sensitivity of a Sequential Approximate Optimisation algorithm (SAO) proposed in [1-4] to an increasing number of design variables and compares it with two other algorithms: an Evolutionary Strategy (ES) and an Evolutionary version of the SAO (ESAO). In addition, it observes the influence of different Designs Of Experiments used with the SAO. It is concluded that the SAO is very capable and efficient and its combination with an ES is not beneficial. Moreover, the use of SAO with Fractional Factorial Design is the most efficient method, rather than Full Factorial Design as proposed in [1-4]

The distribution of ant nest (Hymenoptera, Formicidae) in coastal grey dunes of Flanders (Belgium) and their relationship to myrmecochorous plants

During the summer of 2001, we conducted a study on the spatial distribution of ants in coastal grey dunes (Oostduinkerke, Western Flanders, Belgium). Nest locations of the most abundant ant species were analysed with multivariate techniques. Tetramorium caespitum frequented moss-dominated vegetation, whereas Myrmica sabuleti, M. scabrinodis, Lasius flavus and L. meridionalis preferred grassy vegetations. Formica cunicularia and L. psammophilus occurred in all types of grey dune vegetation. According to recent literature, a positive spatial relationship can exist between the positioning of ant nests and the location of the myrmecochorous plants Viola curtisii, Luzula campestris and Polygala vulgaris in coastal dunes. Neither preliminary investigations, nor our study could confirm this significant positive relationship: the occurrence of myrmecochorous plants seems to be independent of the proximity of nests. It is possible that relationships are masked by a high turnover rate of the nest sites or by a restricted seedling establishment. We did not, however, observe ants transporting seeds of Viola, Luzula or Polygala in the field, possibly indicating the inefficiency of searching for those seeds in areas where population densities of these plants are rather low and other food sources are abundantly available

Biological evaluation of the Belgian beaches by means of terrestrial invertebrates

Beaches belong to the least studied ecosystems, although they contain typical habitats for a large amount of specialised terrestrial invertebrates. This specific beach fauna was quite diverse along the Belgian coast at the beginning of the twentieth century. Especially species bound to organic matter, washed up on the tide line, were well represented. As a result of the development of mass tourism, most of our beaches are subject to mechanical beach cleaning and the suppletion of sand. These activities are believed to be responsible for the degradation of the original habitat. However, documentation on this topic was scarce and evidence of negative effects on local biodiversity was lacking. Therefore, the main goal of this research was to make an inventory of the terrestrial arthropod fauna on Flemish beaches and analysing temporal and spatial variation, in function of abiotic components such as the degree of recreation and the intensity of mechanical beach cleaning. The main conclusion is that a high degree of recreation and mechanical beach cleaning indeed has a negative influence on the richness of the species bound to organic detritus and also induces a change in community structure of terrestrial invertebrates along the Flemish coast. Secondly, predators and even parasites are also indirectly influenced by these anthropogenic disturbances, as a result of the declining prey population. Excluding or at least reducing these impacts along certain sections of the Flemish coast, might ensure the preservation of the organic detritus on the tide line and hence its associated beach fauna

Nanoparticulate Radiolabelled Quinolines Detect Amyloid Plaques in Mouse Models of Alzheimer's Disease

Detecting aggregated amyloid peptides (Aβ plaques) presents targets for developing biomarkers of Alzheimer's disease (AD). Polymeric n-butyl-2-cyanoacrylate (PBCA) nanoparticles (NPs) were encapsulated with radiolabelled amyloid affinity 125I-clioquinol (CQ, 5-chloro-7-iodo-8-hydroxyquinoline) as in vivo probes. 125I-CQ-PBCA NPs crossed the BBB (2.3 ± 0.9 ID/g) (P < .05) in the WT mouse (N = 210), compared to 125I-CQ (1.0 ± 0.4 ID/g). 125I-CQ-PBCA NP brain uptake increased in AD transgenic mice (APP/PS1) versus WT (N = 38; 2.54 × 105 ± 5.31 × 104 DLU/mm2; versus 1.98 × 105 ± 2.22 × 104 DLU/mm2) and in APP/PS1/Tau. Brain increases were in mice intracranially injected with aggregated Aβ42 peptide (N = 17; 7.19 × 105 ± 1.25 × 105 DLU/mm2), versus WT (6.07 × 105 ± 7.47 × 104 DLU/mm2). Storage phosphor imaging and histopathological staining of the plaques, Fe2+ and Cu2+, validated results. 125I-CQ-PBCA NPs have specificity for Aβ in vitro and in vivo and are promising as in vivo SPECT (123I), or PET (124I) amyloid imaging agents