THE VOYAGE:
MYTILUS GALLOPROVINCIALIS

TWO MUSSELS

The Dry Dock was created for a specific infrastructural purpose, yet an incidental and unforeseeable non-human contribution is made along with the process. Ecological transformation is most evident in a process like reclamation, and less noticeable in the after effects, such as the global transportation of creatures. Yet these two stories are directly intertwined.

Mytilus galloprovincialis (Northern Hemisphere)
Mytilus planulatus (Southern Hemisphere)

Blue Mussels are global creatures. They are opportunistic wayfares, hitching rides on the materials moving across the Earth’s oceans. Timber, buoyant, roughly textured and abundant, it provides an ideal surface for Mussels to lease onto with their concrete-like adhesive secretions. As such, the timber hulls of large vessels became perfect mobile habitats for the Mytilus galloprovincialis, one of three principal species belonging to the Mytilus Edulis Complex. Making its home within the warm waters of the Western Mediterranean Sea, M. galloprovincialis has long made use of the material objects travelling along the local coastline and beyond. Yet with the construction of the Suez Canal, European shipping companies now had access to a faster and more affordable route through the Mediterranean Sea. Through rapid industrialisation of urban centres, the reshaping of docks and ports and increasing flow of ships moving between them, M. galloprovincialis was able to discreetly enter many of these expanding ports throughout the world.

Sydney Harbour has long been a habitat for mussel species. Mytilus planulatus has been present on the Eastern Australian coast since the Pleistocene Period, and within the Central Sydney Estuary it has provided a platform to facilitate complex multi-species assemblages around the rocky intertidal shores. Despite the transformation of over 86% of the harbour’s coastline (G. Birch), M. planulatus have continued to make habitat on the introduced artificial structures which now line the foreshore (Glasby and Connel 2001). Yet today M. planulatus is irreversibly altered. In defiance of conventional nomenclature, the Blue Mussel found around the Central Sydney Estuary is neither the native M. planulatus nor the european M. galloprvincialis, instead it is a genetic hybrid of the two.

The relationship between M. galloprovincialis and M. planulatus reveals some of the hidden ways in which colonial practices from the early industrialisation of Sydney Harbour continue to impact local ecosystems. The two mussels were brought back into contact after more than 100,000 years of isolation, when vessels moving from the Eastern Mediterranean Sea unwittingly biofouled with M. galloprovincialis, entered Sydney Harbour. Spaces like Mort’s Dock, where these vessels were overhauled for their return voyage to Europe, represent epicentres of such a process. The archive reveals the intimate relationship between the human operations within the drydock, and the non-human narratives occurring alongside them. The preparation methods used within the drydock, ‘scraped, cleaned and painted’, refers to reversing the effects of biofouling on the hulls of ships.

Ships would make berth for long periods of time, submerged in the warm shallow water within the slip waiting to be cleaned. Beneath the surface, ‘clusters of shells’ some as ‘large as an ordinary vase’ would perform their reproductive practices - releasing spores while leased onto the side of hulls. Then, scraped in the drydock, the creatures removed from the hull were likely discarded back into the bay. The waters within the Central Sydney Estuary were long treated as trash receptacles for byproducts of industrialisation (Stanley Jevons), it's not a stretch to imagine the biofoul material removed from hulls was transferred back into the water in a similar way.

With the aid of human hands and vessels, M. galloprovincialis has spread through the harbour, and extensively across the eastern Australian Coastline.

INTROGRESSION

M. galloprovincialis and M. planulatus have been interbreeding since introduction. Genetic gene transfer through a processes of introgression and subsequent masculinisation, female.

To the human eye, M. galloprovincialis is identical to M. planulatus. The striated shell of Mytilus galloprovincialis is a gradient from brown at its anterior, to a blueish-black at its posterior edge. It is irregularly worn, elongate, equivalve and inequilateral.

To the non-human, M. galloprovincialis is litered with microscopic differences. When compared to M. planulatus, their shells are smooth. They have fewer undulations and crevices for other local creatures to hold onto. They do not provide the same complexity to allow for multi-species leasing.

Across the bay in nearby Kiribilli, mats of algae were observed to only form in thin beds beneath M. galloprovincialis (intertidal assemblages pg 1763). Before, M. planulatus rather than in complex 3D formations across the shells as observed where native mussels lease. Studies in South Africa suggest that even when removed, the habitat will remain at lower health when compared with native communities.

RE-RECLAMATION

The coastline at the site of Mort’s Dock transitioned from a rocky intertidal foreshore to seawall when some 300 metres of the foreshore was reclaimed in 1853 (reclamation in sydney harbour).

Eventually Mort’s Dock would be shut down, and operations moved to Woolwich Dock, the largest Dry Dock in Sydney Harbour’s history. The dock would eventually be infilled, with the intention to convert what was once a privatised foreshore into public space. Methods of cleaning employed here are taken elsewhere, and less frequent, due to developments in antifouling paints - a material which came with its own ecological risks due to the inclusion of chemicals like Tributyltin.

Morts Dock has been turned into a park. Today, all that remains above its surface is a small sandstone wall which demarcates half of the Dry Dock’s shape, and the historic lock which allowed for the dock to be drained, is still home to a substantial colony of Sydney Rock Oysters, intermingled with Blue Mussels.