Abstract
The present study investigated the drag increase on aquaculture nets due to biofouling of the colonial hydroid Ectopleura larynx. It had two main parts: firstly the growth characteristics of E. larynx were investigated by use of field tests at a Norwegian aquaculture site; secondly the hydrodynamic drag on the fouled twines was studied in a towing tank by using fabricated models of net twines with artificial hydroid fouling. In the field tests, the growth of the hydroids was first measured after three weeks of immersion and then again after six weeks. During this interval, the density of hydroids and the thickness of the hydroid stem were almost constant (1.4 hydroids/mm and 0.29 mm, respectively), while the average length of the hydroids increased from 6.4 to 11.2 mm. The hydroid length followed a Rayleigh distribution, while the thickness was normal (Gaussian) distributed. Replicas of twines with three different levels of hydroid growth were made (1.5 hydroids/mm twine, hydroid length 9 mm, 16 mm and 20 mm), and the drag on these twines was measured at different towing velocities (0.1 to 1.4 m/s) and with different twine configurations. For the twine with the shortest hydroids (9 mm), the drag was from 1.5 times (Re=4000) to 2.2 times (Re=1000) the drag on a clean twine. For the longest hydroids (21 mm), the drag was 2 times and 3.8 times, respectively.
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References
Bearman, P. W. and Wadcock, A. J., 1973. The interaction between a pair of circular cylinders normal to a stream, J. Fluid Mech., 61(3): 499–511.
Bloecher, N., Olsen, Y. and Guenther, J., 2013. Variability of biofouling communities on fish cage nets: A 1-year field study at a Norwegian salmon farm, Aquaculture, 416, 302–309.
Braithwaite, R. A., Carrascosa, M. C. C. and McEvoy, L. A., 2007. Biofouling of salmon cage netting and the efficacy of a typical copper-based antifoulant, Aquaculture, 262(2): 219–226.
Braithwaite, R. A. and McEvoy, L. A., 2004. Marine biofouling on fish farms and its remediation, Adv. Mar. Biol., 47, 215–252.
Cronin, E. R., Cheshire, A. C., Clarke, S. M. and Melville, A. J., 1999. An investigation into the composition, biomass and oxygen budget of the fouling community on a tuna aquaculture farm, Biofouling, 13(4): 279–299.
De Nys, R. and Guenther, J., 2009. The impact and control of biofouling in marine finfish aquaculture, in: Advances in Marine Antifouling Coatings and Technologies, Hellio, C., Yebra, D. (Eds.), Woodhead Publishing, pp. 177–221.
Dürr, S. and Watson, D. I., 2009. Biofouling and Antifouling in Aquaculture, in: Biofouling, (Eds. S. Dürr and J. C. Thomason), Wiley-Blackwell, Oxford, UK. doi: 10.1002/9781444315462.ch19.
Fitridge, I., Dempster, T., Guenther, J. and De Nys, R., 2012. The impact and control of biofouling in marine aquaculture: A review, Biofouling, 28(7): 649–669.
Fredheim, A., 2005. Current Forces on Net Structures, Ph.D. Thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, Department of Marine Technology, Trondheim, VIII, pp. 130 s.
Gili, J. M. and Hughes, R. G., 1995. The ecology of marine benthic hydroids, Oceanography and Marine Biology: An Annual Review, 43(12): 351–426.
Guenther, J., Carl, C. and Sunde, L. M., 2009. The effects of colour and copper on the settlement of the hydroid Ectopleura larynx on aquaculture nets in Norway, Aquaculture, 292(3): 252–255.
Hayward, P. J. and Ryland, J. S., 1990. The Marine Fauna of the British Isles and North-West Europe: Introduction and Protozoans to Arthropods, Clarendon Press.
Hoerner, S. F., 1965. Fluid-Dynamic Drag: Practical Information on Aerodynamic Drag and Hydrodynamic Resistance, 3rd Ed., S. F. Hoerner, Midland Park, N. J.
Kvenseth, P. G., 1996. Large-scale use of wrasse to control sea lice and net fouling in salmon farms in Norway, in: Wrasse: Biology and Use in Aquaculture, Sayer, M. D. J., Treasurer, J. W., Costello, M. J. (Eds.), Wiley-Blackwell, Cambridge, UK, pp. 196–203.
Lader, P., Enerhaug, B., Fredheim, A., Klebert, P. and Pettersen, B., 2014. Forces on a cruciform/sphere structure in uniform current, Ocean Eng., 82, 180–190.
Palczynski, M. J., 2000. Fish Cage Physical Modeling, Master’s Degree Thesis submitted in partial requirement for the Ocean Engineering degree program, University of New Hampshire, Durham, NH, USA, pp.111.
Pyefinch, K. and Downing, F. S., 1949. Notes on the general biology of Tubularia larynx Ellis & Solander, Journal of the Marine Biological Association of the United Kingdom, 28(1): 21–43.
Schuchert, P., 2010. The European athecate hydroids and their medusae (Hydrozoa, Cnidaria): Capitata Part 2, Revue suisse de Zoologie, 117(3): 337–555.
Swift, M. R., Fredriksson, D. W., Unrein, A., Fullerton, B., Patursson, O. and Baldwin, K., 2006. Drag force acting on biofouled net panels, Aquacult. Eng., 35(3): 292–299.
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This work was fanatically supported by the Norwegian Research Council through the project Hydroids on aquaculture constructions in Norway (190463/S40), and the CREATE Centre for Aquaculture Technology.
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Lader, P., Fredriksson, D.W., Guenther, J. et al. Drag on hydroid-fouled nets — An experimental approach. China Ocean Eng 29, 369–389 (2015). https://doi.org/10.1007/s13344-015-0026-y
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DOI: https://doi.org/10.1007/s13344-015-0026-y