Arid ecosystems are strongly limited by water availability, and precipitation plays a major role in the dynamics of all species arid regions, as well ecosystem processes that occur there. However, understanding how biotic interactions mediate long-term responses dryland to rainfall remains very fragmented. We report on unique large-scale field experiment spanning 25 yr three trophic levels (pla...

The feeding habits and trophic level of Himantura gerrardi were studied according to sex and size classes utilizing 80 individuals obtained using bottom trawl between May and December 2014 from Oman Sea. Collected specimens were divided in three size classes (small 58 cm) based on disk width (DW). Preys were identified in seven main zoological categories, where crustacean and polychaetes were t...

We show that cerebral endothelial cells secrete trophic factors that support the survival and proliferation of rat oligodendrocyte precursor cells (OPCs). This OPC-supportive phenomenon was mediated by Akt and Src signaling pathways. Noncytotoxic levels of oxidative stress downregulate trophic factor production and disrupt the ability of cerebral endothelial cells to support OPCs. These data su...

i Table of contents iv List of figures and tables vi Acknowledgements xv Author’s declaration xvi Chapter 1: General introduction 1.1 Marine ecosystem change 1 1.2 Theoretical considerations: seabirds as indicators of marine ecosystem change 4 1.3 Seabirds-Climate change effects 5 1.4 Seabirds-Fishery interactions 8 1.5 Conclusions 11 1.6 Aims of the thesis 11 Chapter 2: Influence of climate ch...