MICROALGAE AS BIODETERIOGENS OF STONE CULTURAL HERITAGE: QUALITATIVE AND QUANTITATIVE RESEARCH BY NON-CONTACT TECHNIQUES

Biological colonisation of stone is one of the main problems related to monuments and buildings conservation. It is amply recognised that microalgae have the greatest ecological importance as pioneer colonisers of stone materials, conducting to aesthetic, physical and chemical damages. Their deterioration potential is related with their photoautotrophic nature, using the mineral components of stone substrates and sunlight as energy source without any presence of organic matter. Stone biodeterioration by microalgae has been assessed by several authors. Most of the employed methodologies for microbial identification and monitoring are time-consuming and require extensive sampling. In addition, the scaffolding and sampling procedures required may also transform the researcher in a biodeteriorating agent itself. In this chapter, non-contact techniques for colonisation detection and monitoring are proposed in order to fulfil the mission of heritage preservation. In vivo chlorophyll a fluorescence and digital imag