1 Gis - Based Environmental Analysis , Remote Sensing and Niche Modeling of Seaweed Communities

In the face of global change, spatially explicit studies or meta-analyses of published species data are much needed to understand the impact of the changing environment on living organisms, for instance by modeling and mapping species’ distributional shifts. A Nature Editorial (2008) recently discussed the need for spatially explicit biological data, stating that the absence or inaccuracy of geographical coordinates associated to every single sample prohibits, or at least jeopardizes, such studies in any research field. In this chapter, we show how geographic techniques such as remote sensing and applications based on geographic information systems (GIS) are the key to document changes in marine benthic macroalgal communities. Our aim is to introduce the evolution and basic principles of GIS and remote sensing to the phycological community and demonstrate their application in studies of marine macroalgae. Next, we review current geographical methods and techniques showing specific advantages and difficulties in spatial seaweed analyses. We conclude by demonstrating a remarkable lack of spatial data in seaweed studies to date and hence suggesting research priorities and new applications to gain more insight in global change-related seaweed issues.