Previous work has shown that organosilica-based xerogels have the potential to control biofouling. In this study, modifications of chemistry were investigated with respect to their resistance to marine slimes and to settlement of barnacle cyprids. Adhesion force measurements of bovine serum albumin (BSA)-coated atomic force microscopy (AFM) tips to xerogel surfaces prepared from aminopropylsilyl-, fluorocarbonsilyl-, and hydrocarbonsilylcontaining precursors, indicated that adhesion was significantly less on the xerogel surfaces in comparison to a poly(dimethylsiloxane) elastomer (PDMSE) standard. The strength of adhesion of BSA on the xerogels was highest on surfaces with the highest and the lowest critical surface tensions, g C and surface energies, g S , and duplicated the 'Baier curve'. The attachment to and removal of cells of the diatom Navicula perminuta from a similar series of xerogel surfaces were examined. Initial attachment of cells was comparable on all of the xerogel surfaces, but the percentage removal of attached cells by hydrodynamic shear stress increased with g C and increased wettability as measured by the static water contact angle, y Ws , of the xerogel surfaces. The percentage removal of cells of Navicula was linearly correlated with both properties (R 2 ¼ 0.74 for percentage removal as a function of y Ws and R 2 ¼ 0.69 for percentage removal as a function of g C ). Several of the aminopropylsilyl-containing xerogels showed significantly greater removal of Navicula compared to a PDMSE standard. Cypris larvae of the barnacle B. amphitrite showed preferred settlement on hydrophilic/higher energy surfaces. Settlement was linearly correlated with y Ws (R 2 ¼ 0.84) and g C (R 2 ¼ 0.84). Hydrophilic xerogels should prove useful as coatings for boats in regions where fouling is dominated by microfouling (protein and diatom slimes).

ABSTRACT1. Assessments of anthropogenic impacts on cetaceans are often constrained by limited data on the extent to which these species use particular areas.2. Timing porpoise detectors (T-PODs) are autonomous data recorders for detecting cetacean echolocation clicks, potentially providing cost-effective opportunities for monitoring cetacean occurrence.3. The performance of T-PODs was assessed in three areas off the Scottish east coast, where the relative occurrence of bottlenose dolphins and harbour porpoises was known to differ. Land-based observations in one area compared visual and acoustic detections of dolphins, while direct hydrophone recordings of dolphin echolocation clicks were compared with T-POD detections during boat surveys.4. Land-based surveys recorded 89 groups of dolphins within 900 m of the T-POD. All groups spending 430 min in the area were detected on the T-POD, and the probability of detection declined in relation to distance from the recording site.5. The number of dolphin clicks recorded on the independent hydrophone system was significantly related to the number detected by a T-POD. Between pairs of T-PODs, there was also significant correlation with the numbers of clicks recorded in each hour, both for channels set to detect bottlenose dolphins and for channels set to detect harbour porpoises.6. Year-round deployments of paired T-PODs detected significant geographical variation in detections for both bottlenose dolphins and harbour porpoises. This pattern reflected published data from visual surveys, where dolphins occurred most regularly within the Moray Firth Special Area of Conservation, and porpoises were sighted more regularly in offshore waters.7. T-PODs do not detect all cetaceans in the area, and care must be taken when interpreting data from mixed species communities. Nevertheless, these results confirm that T-PODs provide an effective method for monitoring the occurrence of bottlenose dolphins and harbour porpoises, and provide excellent potential for collecting baseline data from poorly studied areas and monitoring long-term temporal change in key areas of interest.

Poly(ethylene glycol) dimethacrylate (PEGDMA), PEGDMA-co-glycidyl methacrylate (PEGDMA-co-GMA), and PEGDMA-co-hydroxyethyl methacrylate (PEGDMA-co-HEMA) hydrogels were polymerized using ammonium persulfate and ascorbic acid as radical initiators. Surface energies of the hydrogels and a standard, poly(dimethylsiloxane) elastomer (PDMSe), were characterized using captive bubble and sessile drop measurements, respectively (γ = 52 mN/m, γ(0) = 19 mN/m). The chemical composition of the hydrogels was characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. All three hydrogel compositions reduced significantly (p = 0.05) initial attachment of zoospores of the green alga Ulva linza (up to 97%), cells of the diatom Navicula incerta (up to 58%) and the bacterium Cobetia marina (up to 62%), compared to a smooth PDMSe standard. A shear stress (45 Pa), generated in a water channel, eliminated up to 95% of the initially attached cells of Navicula from the smooth hydrogel surfaces relative to smooth PDMSe surfaces. Compared to the PDMSe standard, 79% of the cells of C. marina were removed from all smooth hydrogel compositions when exposed to a 50 Pa wall shear stress. Attachment of spores of the green alga Ulva to microtopographies replicated in PEGDMA-co-HEMA was also evaluated. The Sharklet AF microtopography patterned, PEGDMA-co-HEMA surfaces reduced attachment of spores of Ulva by 97% compared to a smooth PDMSe standard. The attachment densities of spores to engineered microtopographies in PDMSe and PEGDMA-co-HEMA were shown to correlate with a modified attachment model through the inclusion of a surface energy term. Attachment densities of spores of Ulva to engineered topographies replicated in a material other than PDMSe are now correlated with the attachment model (R(2) = 0.80).