The rocky shores of the north-east Atlantic have been long studied. Our focus is from Gibraltar to Norway plus the Azores and Iceland. Phylogeographic processes shape biogeographic patterns of biodiversity. Long-term and broadscale studies have shown the responses of biota to past climate fluctuations and more recent anthropogenic climate change. Inter- and intra-specific species interactions along sharp local environmental gradients shape distributions and community structure and hence ecosystem functioning. Shifts in domination by fucoids in shelter to barnacles/mussels in exposure are mediated by grazing by patellid limpets. Further south fucoids become increasingly rare, with species disappearing or restricted to estuarine refuges, caused by greater desiccation and grazing pressure. Mesoscale processes influence bottom-up nutrient forcing and larval supply, hence affecting species abundance and distribution, and can be proximate factors setting range edges (e.g., the English Channel, the Iberian Peninsula). Impacts of invasive non-native species are reviewed. Knowledge gaps such as the work on rockpools and host–parasite dynamics are also outlined.
This chapter reviews the broad area of biofilm detachment, the mechanisms of detachment and the methods used to study this important process. Two case studies are included: the first of these focuses on the control of clinical biofilms; the second case study examines detachment in the water industry.
Biofilms are dynamic structures found in a wide variety of both natural and man-made environments. Their formation has been well studied; for example, Characklis (1990) described eight different stages of biofilm accumulation (Table 1 and Fig. 1). There has been much research into the initial attachment of micro-organisms to surfaces, including the effect of electrostatic interactions and electrochemical forces (Bos et al., 1999). The physiological changes that attaching cells undergo have also been examined; for example, the production of surface appendages such as fimbriae (Austin et al., 1998). In contrast to the work undertaken on attachment, detachment has received little attention although many researchers regard it as a crucial stage of biofilm development (Stewart, 1993; Allison et al., 1999).
Bryers (1988) classified the detachment process into four separate groups: abrasion, grazing, erosion and sloughing. Detachment from the biofilm can be directly caused by the collision or rubbing together of surfaces on which the biofilm has developed, leading to abrasive detachment. Larger organisms feeding on the biofilm can indirectly cause detachment through grazing. Erosion and sloughing refer to physical or chemical processes, which indirectly affect the biofilm structure, leading to detachment. Erosion refers to the continual removal of cells or small groups of cells from the biofilm, whereas sloughing is the loss of discrete amounts of biofilm.
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