Description: 31st Annual Conference of IAMSLIC held 10-14 October, 2005 at Rome, Italy

Description: 32nd Annual Conference of IAMSLIC held 8-12 October, 2006 at Portland, Oregon, USA

Description: 34th Annual Conference of IAMSLIC held 14-18 September, 2008 at Suva, Fiji

Description: 33rd Annual Conference of IAMSLIC held 7-11 October, 2007 at Sarasota, Florida, USA

Description: Fouling communities are distributed worldwide, particularly in shallow and exposed marine systems. Due to their fast growth and their capacity to settle on artificial surfaces, these assemblages represent a suitable study system for ecologists and are therefore often used to investigate ecological models. Investigating broad scale ecological models has been of key interest since the time of the famous naturalist Charles Darwin. Two examples of well recognized macro-ecological patterns are i) the ‘latitudinal gradient of species richness’ and ii) the ‘relationship between local and regional diversity’. The first is the oldest paradigm about a large-scale ecological pattern and simply states that the tropical regions are richer in species than temperate and polar regions at higher latitudes. However, when exploring global diversity patterns, it is essential to comprehend not only the importance of differences in spatial scale for the observed patterns, but also how diversity at one scale may relate to diversity at a different scale. Indeed, several studies have shown that the number of species within small localities may increase either linearly or asymptotically with regional species richness (relationship between local and regional diversity). Exploring global diversity patterns still constitutes an important challenge for ecologists because it reflects the need to determine the current status of biodiversity. With the knowledge of today’s biodiversity, we can predict its future status and, as a consequence, be able to provide new answers to its probable response to phenomena such as climate change. In the present work, I investigate global diversity patterns in marine fouling communities, mainly by examining the previously mentioned macro-ecological patterns, i.e. the latitudinal gradient of species richness and the relationship between local and regional diversity. Previous studies investigating the local-regional diversity relationship have often assessed the number of species in a region by consulting available species lists. However, regional species pools based on such inventories may include species not susceptible to recruit into the community considered because they are restricted to different habitats and seasons. With the purpose of dealing with these difficulties, a few investigations have estimated regional richness based on local samples but confirmed a strong bias in relation to sampling effort. In order to optimize the quality of regional richness estimations, the current study develops a new statistical tool for estimating regional richness based on a limited number of replicates. Using three data-sets with a large number of replicates from different temperate shallow water habitats, I compare common richness estimators against the asymptote of the species accumulation curve, which was used as a reference for true regional richness. Subsequently and more importantly, the mis-estimation was quantified as a function of sampling effort. To complete this work, the relationship between local and regional diversity was expanded by integrating two categories of diversity (taxonomic and functional) and different successional stages at two different scales: European and global. At the European scale, the shape of the pattern was compared for different methods in assessing regional richness: species colonizing during a given period (transient regional richness) versus species colonizing during any phase of the experiment (total regional richness). At the global scale, I further examine whether the diversity of local communities is affected by parameters other than regional richness, such as number of functional groups or availability of resources. The results of this investigation support a clear influence of latitude on local species richness in marine fouling communities. In Chapter I, I show that tropical regions hold more marine fouling species when compared to areas at higher latitudes. In what concerns the regional richness assessment, I conclude that regional richness can be estimated based on a limited number of samples and that the quality of the estimation increases with sample effort. Moreover, the strength of the inevitable mis-estimation can be quantified (Chapter II). In addition, at the European scale (Chapter III), it was found that the shape of the relationship between local and regional diversity is sensitive to successional stage, the way regional richness is estimated and the dimension of diversity considered. The relevant regional richness, i.e. the regionally available colonizers, seems to vary in time and is larger when pooling all sampling events. As a consequence, the relationship between local and regional diversity is also influenced by the method in which regional richness is estimated. At a global scale (Chapter IV), the relationship between local and regional diversity in fouling assemblages is also affected by the succession process, if either taxonomic or functional diversity are considered. Local taxonomic diversity exhibits saturation at early stages of succession while saturation of local functional richness occurs later. In addition, functional groups were reported as the most influential predictor for local species richness.

Description: The statoliths of cephalopods are calcified bio mineral structures found in the gravity receptor system in the head of cuttlefish and squid. They grow throughout the lifetime of the animal and deposit microscopically visible daily increments similar to the annual rings in tree stems. Statolith growth and composition are linked to environmental factors. Thus, the statolith reveals the biological history of each individual cephalopod. If a relationship can be established between the composition of a growth layer of the statolith and the ambient water properties, then the statolith chemistry becomes a predictor of the surrounding water chemistry and/or temperature. Provided that statolith material is not altered or resorbed after deposition, the statolith becomes a permanent archive of environmental conditions and may provide information on habitat use, timing of exposure to a pollutant, and timing of migrations. Several micro analytical state-of-the-art techniques have been applied in this thesis to investigate the spatially resolved chemical composition of cephalopod statoliths. Recent applications of these methods include mainly geological samples, which do not contain organic compounds. Therefore a considerable part of this project focussed on adjusting and optimising the respective methods to the analyses of biogenic aragonite intergrown with organic compounds. In this thesis, the influence of different environmental factors on the chemical composition of cephalopod statoliths was investigated. On the basis of laboratory experiments under controlled conditions, it is now possible to qualify the influences of salinity, temperature and diet on the concentrations of several elements in the statoliths. Analytical results indicate that the incorporation of a number of elements is influenced by environmental factors. Barium and iodine appear to be the most suitable indicators for temperature. The incorporation of strontium into cephalopod statoliths, however seems to be influenced to a greater extent by diet than by the surrounding water. This is contradictory to results from corals and fish otoliths, where strontium is a well-established indicator for both temperature and salinity. The suitability of statolith micro-chemistry for field-studies has been proven as well. Statolith trace element compositional zoning reflects very well the life history and ontogenetic habitat-shifts of the boreoatlantic armhook squid Gonatus fabricii. Further, this thesis gives valuable insights into the microstructure of statoliths and the elemental nano-scale distribution in daily increments. For the first time, the application of NanoSIMS NS50 provided distribution patterns of calcium, strontium and sodium in cephalopod statoliths with a spatial resolution of 400nm. The results of this study provide an essential basis for future investigations in the field, probably leading into further understanding of yet unknown migration patterns and spawning grounds of various cephalopod species. Applying these future approaches could establish a consolidated biological knowledge on cephalopod species and stocks, and therefore may contribute to an effective and sustainable management of this both ecologically and economically valuable resource.