Arrival of The Quagga Mussel (Driessena bugensis) Poses Big Problems for the UK – Dan Mills
Earlier this month and to a relatively forgettable fanfare, the first British record of a highly invasive bivalve mollusc Driessena bugensis was confirmed near Wraysbury reservoir, West London. It is a species widely known as the Quagga mussel.
Quagga mussels have traits which are similar to other successful invasive species (see Francis and Chadwick, 2012) As a highly effective coloniser capable of rapid reproduction and dispersal throughout freshwater systems, the tendency of the Quagga mussel at high densities to dominate and reengineer hard substrates in freshwater environments makes it a priority issue for the Environment Agency.
Indeed, throughout the eastern United States where the Quagga mussel has already invaded, the animal has been seen to rapidly swamp river channels and lake beds in a manner that can significantly reduce habitats that native invertebrates, plants and fish require to survive or reproduce. Furthermore, the ability of the tenacious organism (and the closely related Zebra Mussel) to clog up piping, foul boat hulls, and strain engineering structures has reportedly cost the American water industry an estimated $1billion to treat annually (Pimentel et al., 2005).
As such, and despite being only one of a series of other invasive species originating from Ukraine’s Ponto-Caspian region, the Quagga mussel is considered a significantly more potent ecological and economic threat than any other new invasive to Britain. Indeed a large panel of experts recently placed it on top of a list of 30 as the single most threatening of all potential non-native species to the UK in general (See: Roy et al., 2014).
While this at first may seem a strong placement considering the effects already evidenced by alien species such as the American Signal crayfish and Asian Topmouth gudgeon; it is arguably not merely appropriate, but even worse than stated when looking beyond the direct ecological and economic issues mentioned above.
For example, it is possible that the development of pioneering Quagga mussel beds in the UK would provide an optimal environment to facilitate the arrival of other Ponto-Caspian species. Indeed, the jagged, complex and clustered beds typically formed by such mussels provide excellent habitat and refugia for voracious animals such as the Dikerogammarus ‘Killer’ shrimps which even exhibit a mutual striped patterning probably co-evolved for camouflage purposes (Madgwick & Aldridge, 2011).
These self-reinforcing interactions between Ponto Caspian Invasives enhance their ability to spread outside their native range and have been described as a mechanism for ‘invasional meltdown’ (Gallardo & Aldridge, 2014), leading towards a situation where Ponto Caspian communities could effectively dominate UK freshwater fauna. Articulating such concerns, Cambridge University ecologist Dr. David Aldridge suggested that ‘very soon’ in UK freshwaters, 90% of the biomass could be from non-native organisms (in BBC., 2014).
While this figure might appear relatively alarmist, if a ‘meltdown’ phenomenon develops even on a limited scale, the success of charismatic plant and animal species long associated with particular British rivers could be placed in significant uncertainty and economic costs could go beyond the aforementioned mitigation for pipe blockages and general bio fouling.
A reduction of traditional fisheries used for recreational angling is an obvious example of where a popular industry could suffer, however there could be many other wider reaching and unpredictable implications. Arguably overlooked is an issue relating to the UK’s legal obligation to monitor water quality for pollution under the EU’s Water Framework Directive.
Here, the condition of UK rivers are to a significant degree monitored using ecological assessments where the presence or absence of particular species indicate certain aquatic conditions. This method has been progressively fine-tuned by the Environment Agency in recent years however is one approached entirely using native indicator species. In a future where some or many of these are replaced by non-natives, it would be difficult to comparably monitor water quality using the ecology present in UK rivers. Aside from a resultant black hole in scientific understanding, heavy fines could be issued by the European Commission for not fulfilling the legal duty of effective water quality monitoring, -a potentially unpopular burden for the British taxpayer.
Such consequences lie beyond the ‘first glance’ possibilities from a more widespread dispersal of the Quagga Mussel, highlighting a complex severity to the issue that arguably justifies its position as the most worrying invasive species in the UK.
Ultimately though, the impact of the Quagga mussel depends on quick and robust actions to prevent further spread. One method might involve eradication through the controlled poisoning of effected waters (e.g. Aldridge et al., 2006), however justifying the financing of this approach to policy makers is difficult because great uncertainty remains regarding how successful or damaging the Quagga Mussel might prove in UK freshwaters.
Assessing the success of the closely related Zebra mussel is probably a reasonable starting point. Here, some foreboding facts are available. Zebra mussels are now highly successful in many of the UK’s major rivers, cost Anglian Water alone £500million to mitigate per year (BBC., 2012), and where found to be present have never been permanently removed.
If left to get similarly out of hand, it might take some serious muscle to tackle the Quagga.
BBC, 2012. ‘Giving an invasive Water pest the bullet,’ Smale, W., 3rd Febuary, accessible at: http://www.bbc.co.uk/news/business-16788183
BBC, 2014. ‘UK Waterways face ‘Invasional Meltdown’ from European Organisms,’ McGrath, M., 13th October, accessible at: http://www.bbc.co.uk/news/science-environment-29570347
For more information: http://www.nonnativespecies.org/factsheet/factsheet.cfm?speciesId=3831
Alridge, D. C., Elliott, P., & Moggridge, G. D., 2006. ‘Microencapsulated BioBullets for the Control of Biofouling Zebra Mussels,’ Environmental Science and Technology, 40: 975-979.
Francis, R.A. & Chadwick, M.A., 2012. ‘Invasive alien species in freshwater ecosystems: a brief overview’ In: Francis, R.A. A Handbook of Global Freshwater Invasive Species. London: Routledge. 3-21.
Gallardo, B., & Aldridge, D. C., 2014. ‘Is Great Britain heading for a Ponto-Caspian invasional meltdown?’ Journal of Applied Ecology, DOI: 10.1111/1365-2664.12348 (open access)
Madgwick, G., & Aldridge, D., 2011. ‘Killer Shrimps in Britain: hype or horror? The Facts about our Latest Invasive Animal,’ In: British Wildlife, August 2011, pp. 408-412.
Pimentel, D., Zuniga, R. & Morrison, D., 2005. ‘Update on the Environmental and Economic Costs Associated with Alien-invasive Species in the United States,’ Ecological Economics, 273-288, 273-288.
Roy, H. E., Peyton, J., Aldridge, D. C., Bantock, T., Blackburn, T. M., Britton, R., Clark, P., Cook, E., Dehen-Schmutz, K., Dines, T., Dobson, M., Edwards, F., Harrower, C., Harvey, M. C., Minchin, D., Noble, D. G., Parrot, D., Pocock, M. J. O., Preston, C. D., Roy, S., Salisbury, A., Schonrogge, K., Sewell, J., Shaw, R. H., Stebbing, P., Stewart, A. J. A., Walker, K. J., 2014. ‘Horizon-scanning for Invasive Alien Species with the Potential to Threaten Biodiversity in Great Britain,’ Global Change Biology, DOI: 10.1111/gcb.12603 (open access)
Dan Mills is currently a NERC London DTP student. He completed his MSc in Aquatic Resource Management, King’s College London in 2012. He can be contacted on: daniel.mills.14 [ @ ] ucl.ac.uk