OP2352 Investigating the bi-directional impacts of dredging on seagrass restoration in the River Tees estuary

NERC ONE Planet DTP

Dredging of the River Tees for the Teesside enterprise zone (freeport) has been linked with a series of mass marine mortalities (crustaceans, molluscs and echinoderms), with growing evidence of impacts at all levels of the marine food web. The Tees estuary also hosts ongoing habitat improvement programmes, specifically restoration of native seagrass and oyster beds (CASE Partner, Tees River Trust). There is growing concern that dredging (particularly of the Teesworks’ South Bank) will endanger the success of these programmes. South Bank soils are among the most (if not the most) contaminated sediments in the UK, with >70 chemicals exceeding limits for safe disposal at sea, including heavy metals and persistent organic pollutants (POPs). In parallel with ongoing work at NCL into the impacts of pollutant release from dredging, this studentship will assess the risks to seagrass and will also assess to scope for seagrass restoration as a phytoremediation tool. The research spans the following work packages (WP): WP1: Lab scale mesocosm trials; Seagrass will be planted in sediment collected from a range of depths from the Tees; monitoring growth, survival and fitness (PAM fluorometry). WP2: Field validation; Monitor success of outplanting in Tees estuary (growth, survival). WP3: Chemical validation; Sediment, sludge, seagrass and estuarine water will be analysed for metals (EDX fluorescence spectroscopy) [1] and POPs (extraction->solvent evaporation->GC-MS) [2] using analytical standards and validated procedures. WP4: Rhizosphere; Microbial community will be characterised (Illumina MiSeq) to determine microbial shifts and identify microbial routes for bioremediation [3]. WP5: Modelling and outreach; predictive models will be developed to assess impacts on seagrass from dredging for the remain UK Freeport projects will be assessed.

Key Research Gaps and Questions:

1. Will dredging contaminated estuary sediment affect seagrass replanting and restoration success?
2. Can seagrass habitat restoration reduce dredging’s environmental impacts by stabilising the sediment?
3. Will the seagrass and the seagrass rhizosphere play a role in contaminant phytoremediation?

Prerequisites:

Experience with analytical chemistry essential For more information, please contact [Email Address Removed]