Introduction

Work Package 2 looks at ecosystem functioning in the northern North Sea across two major historical economic transitions. First, the emergence of large-scale sea fishing in the centuries around 1000 CE, as documented by archaeological fish remains (aka the 'fish event horizon'), and the subsequent development of export trade from northern 'producer' sites to urbanising southern 'consumer' settlements. Second, the industrialisation of North Sea fisheries from the late 1800s, particularly with the introduction of the steam trawl.

Where and how?

The impact of these economic and cultural processes on the North Sea ecosystem will be traced through both onshore evidence (archaeological remains and historical records) and offshore evidence (sediment cores and sclerochronological series).

Onshore, fish bones from archaeological sites on the UK East Coast and especially Orkney simultaneously provide evidence for intensity of exploitation and for the palaeoecology of major food fish, particularly cod. Compound-specific stable isotope analysis (CSIA) on fish bones will allow us to trace changes in food web structure, while size and growth-ring analysis may reveal changes in fish growth rate in response to fishing pressure or other factors. Ongoing excavations at Skaill Farm, Orkney, will help us to plug a previous gap in post-medieval fish bone data, while historical ecological records will become increasingly important moving into the industrial era.

Offshore, sediment cores from the Fladen Ground and Skagerrak will provide a source of ancient environmental DNA, mapping shifting marine communities through time. Meanwhile, marine shells spanning the past 400-500 years will allow us to construct time-series of trophic structures down to one-year precision, via CSIA on their protein components, and will also provide an additional novel source of aDNA captured from the wider environment.

Taken together, these diverse datasets will allow a joined-up approach to understanding how past human activities have interacted with other factors in shaping the North Sea ecosystem through time.

Research into this transition poses the following questions:

• Did the medieval expansion of marine fishing in the North Sea region significantly impact marine biodiversity/ecosystem functioning?
• What was the relative significance of climatic changes and cultural transitions on the marine ecosystem?
• What was the relative impact of the industrial transition compared with earlier cultural transitions of the last 2,000 years in the North Sea region?