Seven barnacles

What information can we glean from the journeys of these waste objects from marine environments to the intertidal landscapes of Greenwich and Deptford? Entanglement is the interweaving of different ‘things’ across spatial and temporal spaces and how these elements interact with each other; what Karen Barad describes as ‘not a name for the interconnectedness of all being as one, but rather for specifi c material relations of the ongoing differentiating of the world.’7 Nature does not speak as we do and has been marginalised as inferior to humans. Through researching barnacles found on the Thames foreshore, I have discovered the way in which these crustaceans persistently challenge human preconceptions of authority.

The presence of barnacles and other biofouling organisms on the hulls of ships reduces the speed at which they can move and increases the cost of the trip; a ‘10 micron (0.0001 mm) increase in average hull roughness can result in a 0.3 to 1.0 percent increase in fuel consumption.’8 ‘Slime films,’ note Daffron, Lewis and Johnson, ‘can impart powering penalties of 21%, with heavy calcareous biofouling increasing this penalty to 86%’.9 Wooden ships covered in lead sheets fitted to impede marine growth are recorded from as early as 300 BC.10 Moreover, there was still the labour-intensive process of removing barnacles from hulls. ‘Careening’ is the process in which a ship is tilted on its side until its hull is lifted out of the water to be cleaned or repaired.11 Through scientific analysis, G. J. M. Van der Kerk discovered that organotin compounds were potent biocides. Tin is naturally nontoxic to most organisms, but when combined with an organic butyl compound (C4H9) it creates the highly toxic chemical tributyltin (TBT) used on waterborne vessels to prevent biofouling.12 This drastically reduced the cost and time needed for cleaning and repairing a ship. In 1987, the Department of the Environment banned TBT use on small boats due to the harm it causes to non-targeted species such as dog whelks and oysters.13 It is still used on boats longer than 25 meters.

A biocide is ‘a chemical compound or biological product used to kill, control the growth of, or repel a specific organism.’14 The Earth’s bodies of water, including the Thames, have been transformed into environments that serve human endeavours. However, this determination to control things deprives humans from understanding the barnacles’ intricate character. The cement glands barnacles use to attach to hard surfaces are strong enough that they can remain attached even after death. Unless forcefully removed, a barnacle will accompany a vessel on its journey and remain in place even when shipwrecked. The wrecks of the Erebus and Terror were found in 2014 and 2016 respectively. As their hulls lacked biocidal metals, it is possible that the vessels encountered these marine organisms en route. Barnacles develop heavily calcified shells (CaCO3) that grow at different rates depending on the water temperature. To identify the ambient temperature of a shipwreck, researchers analyse differences in the ratio of oxygen isotopes (16O/18O) in the shells.15 The way in which the barnacles bind themselves to moving vessels thus tells us about the environmental conditions of their journeys.

London’s dockyards are ‘persistent places’;16 spaces entangled with organic materials and the intricate stories they carry. The perseverance of objects like barnacles invites us to examine these stories of entanglement. If we allow barnacles to speak naturally, in their nonhuman voices, these crustaceans can provide information on global maritime trade and wreckage site conditions that would otherwise be impossible to discover.