Environmental impact and climate change
The impact of environmental changes on the preservation of underwater cultural heritage
Koen Van Balen, Catholic University of Leuven, Belgium (Chair)
Environmental impact assessment and archaeological heritage
Stefan Wessman, National Board of Antiquities, Finland
Today Environmental Impact Assessment is one of the most important tools for decision makers when it comes to assessment of the possible positive or negative impact that a proposal may have on the environment. The regulations for which type of projects needs an EIA vary from nation to nation, but usually the environment consists of natural, social and economic aspects. In many cases, the assessment of the impact on the cultural heritage seems to be questioned or even regarded unnecessary. During the planning process for the Nord Stream – natural gas pipeline through the Finnish EEZ, the underwater cultural heritage turned out to be one of the key issues when among other finds circa 50 previously unknown shipwrecks were found.
The spread of shipworm in the Baltic
David Gregory, Conservation Department of the National Museum of Denmark, Denmark
Wooden historical shipwrecks are subject to biological degradation in marine environments. Specialized fungi and bacteria are able to degrade the lignocellolytic material present in the wood cell walls but this degradation is, however, very slow compared to the aggressive behaviour of the marine borers such as shipworm. In the Baltic sea, preservation conditions for shipwrecks has been unique due to the absence of marine borers. The low salinity of this water has excluded the marine borers and today the Baltic contains a unique collection of well preserved historical shipwreck and other ancient wooden constructions from the past. However, there have recently been indications of a spread of marine borers (Teredo navalis) into the Baltic, and climatic changes could be one of the reasons. A recently completed EU project, Wreck Protect, aimed to identify and understand if this was real and could be caused by changing environmental conditions in the Baltic. The project also sought to identify best practice methods for preserving wooden UCH in situ. A summary of the project results will be presented.
Global sea level rise and changing erosion
Jan Jarff & Birgit Hünicke, Baltic Sea Research Institute and Helmholtz-Zentrum Geesthacht, Germany.
Presented by: Alar Rosentau, University of Tartu, Faculty of Science and Technology, Estonia
Changes in earth’s climate during the late Pleistocene led to melting continental ice shields marking the end of the last glaciation. Due to the redistribution of water from the continents to the oceans and thermal expansion of sea water the eustatic sea level began to rise continuously. Along the continental margins the rising sea level interferes with the vertical displacement of the earth’s crust: the indirect climatically forced glacioisostatic adjustment. Where the land is subsiding or the rate of eustatic sea level rise exceeds the crustal uplift, the continental shelf and its paleolandscapes are continuously inundated. Here, the migrating highly dynamic shoreline reworks the surface of the paleolandscape. For times of relative rapid sea level rise – as during the late Pleistocene and early Holocene paleolandscapes are rather drawn preserving their former shape then in periods of slow sea level rise (late Holocene) when locally more stable hydrographic forcing reworks intensely the substrate of the coastal zone destroying also eventually archaeological sites. Integrated modelling approaches of climate and glacioisostasy can proof favourable conditions for the preservation of paleolandscapes. These approaches may provide valuable prerequisites for planning and executing of archaeological surveys on the continental shelf.
The appearance of new bacteria (titanic bacterium) and metal corrosion
Henrietta Mann, Dalhousie University, Canada
The sinking of the Titanic in 1912 resulted in global consequences. Some of the important consequences resulted in marine research and the development of submersible technology. After the discovery of the wreck in 1985, scientific research reached a new high due to interest in the well known tragedy.
The rusticle samples were obtained from the 1991 expedition to the wreck. In the years following the attempt to isolate different bacteria which reside in and form the rusticles was undertaken. Due to different mini environmental niches which exist in the rusticles, one species was isolated and identified as Halomonas titanicae. This species is characterized as holo-philic and gram negative. They also have polar and lateral points of origin of flagella indicating that they are peritrichous and motile. It adheres to iron surfaces forming knob-like mounds. The rusticles are highly porous and support a complex variety of microorganisms.
This species can affect marine industry by corroding structures like oil rigs, oil and gas pipelines etc. It can also be used to dispose of old merchant and naval ships and oil rigs in the ocean after they have been cleaned of toxins and oil based products.