Quantification of benthic invertebrate burrow architecture

Project Rationale:

Marine sediments provide habitat for a wide range of organisms and exploitation of this three-dimensional environment is important in mediating major ecosystem properties. In particular, the burrowing and construction activities of sediment-dwelling invertebrates redistribute pore water fluids and sediment particles, profoundly influencing biogeochemical processes. Insights about organism-sediment relations, however, have largely been restricted to a single dimension by tracking the vertical redistribution of various particulate tracers. Whilst these observations have been informative, over reliance on methodology that does not consider multiple planes and geometries perpetuates a limited view of what constitutes the functional role of a species. Detailed 3D characterisations of biogenic structures - tubes, burrows, mounds and pits - are rare and are not a prominent feature of functional classifications. There is a paucity of information on key features of biogenic structures, including length, diameter, volume and configuration, and whether such information is of utility in distinguishing the functional standing of individual species. The aim of this studentship is to use a range of imaging methodologies, including acoustics, high-resolution computed tomography, aerial drones, and/or ground penetrating radar, to develop a functionally relevant typology for biogenic structures and distinguish the role of species activity from biogenic engineering in determining ecosystem functioning.

Methodology:

Reconstruction of biogenic structures of species maintained in aquaria has recently been achieved using micro-focus computed tomography and acoustics to reveal the three-dimensional fine structure of burrow galleries and the effect of fauna on sediment roughness and shear strength. Separately, the spatial extent and geometry of faecal mounds of intertidal populations of Arenicola marina have been quantified at sub-cm resolution using aerial drones and lidar, allowing whole population monitoring of activity in relation to context. These methods will be extended to a range of species representative of the UK soft sediment intertidal and coastal/shelf environments in order to develop a comprehensive understanding of the three-dimensional activities of species. These novel data will be supplemented with species trait and activity metrics derived using mesocosms experiments to enable, for the first time, comprehensive coverage of the mechanisms by which species contribute to functioning. As species behaviour can depend on context at different spatial and temporal scales, laboratory and field measurements of the dynamics of biogenic structures will be assessed in relation to changing environmental and biotic circumstances.

Training:

The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at the National Oceanography Centre in Ocean and Earth Science.

Specific training will include:
1. laboratory-based experimental skills in marine ecology,
2. experimental design and spatio-temporal data analysis techniques,
3. use of technologies capable of non-invasive quantification of structures, including high-resolution computed tomography, aerial drones and lidar, acoustics and ground penetrating radar
4. working with large datasets, and 3D-4D data
5. numerical modelling of flow dynamics
6. image analysis

The student will also gain important research skills such as scientific writing and oral presentation by presenting their research at international conferences/workshops as well as writing up their results in peer-reviewed journals.