Anti-Fouling Biofouling Observations with STRAW Pathfinder Biological Models Biofouling and Sedimentation Sedimentation and Biological Fouling at the Future Site of the Pacific-Ocean Neutrino Experiment Braeden Veenstra for the P-ONE Collaboration Presented by Jakub Stacho Introduction ❖The Pacific-Ocean Neutrino Experiment (P-ONE) is a cubic kilometre scale neutrino telescope that is under construction. [1] ❖P-ONE will be located in the Cascadia Basin, 200 km off the coast of Vancouver Island, at a depth of 2.66 km. ❖The detector is being optimized for searches for high energy astrophysical neutrinos. ❖The first string will be deployed in 2025, and the five-string demonstrator will be deployed in following years. ❖STRings for Absorption Length in Water (STRAW) was a pathfinder instrument deployed in 2018 and recovered in 2023. [2] ❖STRAW made measurements of the ambient light spectrum and attenuation length of the water. [3] ❖Nutrients settle on infrastructure that is placed in natural water. ❖Microbes use these nutrients to colonize surfaces and form what is called a biofilm [5]. ❖The effect is more prominent on upwards facing surfaces, as these are exposed to organic material and sediments. ❖Biofilms reduce the efficiency with which currents remove debris and allow for larger organisms to grow [6][7]. ❖In the case of a neutrino telescope, this causes the upwards facing modules to become less transparent over time. ❖Ambient light due to bioluminescence was monitored continuously [3] ❖Most downlooking STRAW PMTs showed negligible growth. [8] ❖The ratio of upwards to downwards PMT counts was used to estimate the efficiency evolution (thick band shows 1𝝈-confidence interval) [9] ❖This was verified using flasher measurements (data points) [9] POCAMs were LED based flasher units used for calibration SDOMs consisted of one upwards and one downwards facing PMT. Biofilm formation Marine Snow and sediment sticks Secondary Colonization References ❖The gompertz and logistic growth models were fit to data from each STRAW module. These are parameterized by a relative growth rate, carrying capacity and inflection time. [10][11] ❖Fit parameters are used to estimate the time where fouling becomes significant, the relative efficiency extrapolated to 10 years and rate of efficiency loss for each model. Confidence intervals for these estimates are shown, using SDOM3 data as an example. UV-C is well motivated for fouling mitigation[12] Thin coatings are the current industry standard for biofouling prevention. Optically transparent options are available [13] Anti-fouling strategies are currently under investigation for future P-ONE moorings. [1] M. Agostini et al. Nat. Astron, 4:913–915, 2020. [2] M. Boehmer et al. JINST, 2019. [3] N. Bailly et al. Eur. Phys. J. C, 2021. [4] On-deck photographs by F. de Leo Cabrera [5] B. Gottenbos, H.C van der Mei, H. Busscher. Methods in Enzymology, 310:523– 534, 1999. [6] C.C. de Carvalho. Front. Mar. Sci., 5, 2018. [7] M. Herzberg and M. Elimelech. J. Membr. Sci., 295:11–20, 2007. [8] Ocean Networks Canada. SeaTube Pro. https://data.oceannetworks.ca/SeaTube, 2023. [9] P. Hatch, K. Holzapfel, R. Li, C. Spannfellner, and B. Veenstra. PoS(ICRC2023), volume 444, page 1166, 2023. [10] E. Tjørve and K. M. C. Tjørve. Journal of Theoretical Biology, 267:417–425, 2010. [11] K. M. C. Tjørve and E. Tjørve. PLOS ONE, 12:e0178691, 2017. [12] M. Detty, R. Ciriminna, F.V. Bright and M. Pagliaro. Acc. Chem. Res., 47:678–687, 2014. [13] B. Salters and R. Piola. Mar. Tech. Soc. J. 51: 59-70, 2017. 80 m 1000 m 37 m 110 m 70 m 50 m 30 m SDOM1 SDOM2 SDOM3 SDOM4 SDOM5 POCAM1 POCAM2 POCAM3 [4] [4] Preliminary Preliminary [3]