Coastal climate resilience: exploring the value of geodiverse and biodiverse hotspots

The degree of ecological change imposed by climate change on marine species and habitats is of increasing concern (Halpern et al., 2008), and the Intergovernmental Panel on Climate Change (IPCC 2021) warns that limiting global warming to 1.5°C is looking increasingly unachievable. For intertidal and near-coast species, the concomitant increased air and sea temperatures have broad deleterious effects. However, the problems are exacerbated when the suite of co-occurring stressors of increased storminess, sea level rise and urbanisation are considered. These latter will result in a continued proliferation of coastal protection. Such structures have significantly lower biodiversity than equivalent natural habitats. A greater understanding of geodiversity-biodiversity interactions could be used to mitigate climate change risks for marine species, and to increase resilience in intertidal/shallow coast species through enhanced design of appropriate coastal engineering structures.

The novelty of this PhD would be the coupling of both rock material and rock mass properties to assess the combined benefits of geodiversity-biodiversity interactions for improving the climate resilience of marine ecological communities. Creation of a biodiversity ‘risk assessment’ tool is proposed – identifying places at high risk of climate-related stress and those at lower risk, which could become biodiversity climate refugia. The information would underpin design guidelines for eco-engineering practitioners.

This project will address four key research gaps:

1. Managing thermal stress through geodiversity-biodiversity interactions A: rock material and rock mass
Thermal variability of rocky shore systems, driven by wind speed, the tidal cycle, micro-topography, air temperature and solar radiation, can cause body temperatures to fluctuate by >20°C within a few hours and differ significantly between individuals only centimetres apart (Denny et al. 2011, Helmuth et al. 2011). The role of thermal stress has been explored in field-based experimental studies by manipulating temperatures (e.g shading; transplanting individuals across intertidal heights; direct application of heaters), or via thermal properties of differing artificial substrates (colour, material type). What has been less studied is how rock material properties can buffer/mitigate risks of desiccation/thermal stress (e.g. light coloured porous rocks) or increase these risks (e.g. dark rocks with low porosity). To date eco-engineering research has not directly explored links between climate change pressures on organisms (e.g. thermal stress/desiccation risk at low tide) and the types of materials used in experimental studies or operational applications. Similarly, rocky shore geology and geomorphology create topographic complexity on natural rocky shores – creating habitat niches for other species, which is often thermally more sheltered/moister. What is unknown is how these habitat niches provide climate refugia, and how the combination of rock material and rock mass features can create climate resilient biodiversity hotspots in nature, and how we can eco-engineer structures to better mimic this. A combination of field and lab experiments would be designed to test for differences in (i) body temp (ii) survivorship (iii) in situ micro-humidity (iv) growth or fecundity.

2. Reducing thermal stress for ecology via microbial geodiversity-biodiversity interactions
Marine microbial communities are known to greatly differ on different rock materials, and in some porous, calcium-rich materials like limestone, the microorganisms alter the rock materials. In as little as 8-months in a temperate region, cyanobacteria can bore into rock, increasing the porosity and water holding capacity of the rock masses. This has benefits for intertidal species as the rocks retain more moisture through the tidal cycle, reducing risks of thermal pressures. These interactions are poorly studied globally and the benefits they can provide in certain rock materials for intertidal ecology are weakly understood. Novel microcosm studies will be developed to trace active microbial communities as they interact with different rock substrates, acting as biogeomorphic ecosystem engineers gradually creating habitat refugia in some rock types but not others. This will provide information on the most effective microbial-rock interactions, and it will help to inform on the best eco-engineering approaches to consider.

3. Protecting ecology and assets with thermal blankets – what are the risks and benefits?
Organisms, like seaweeds, are known to act as thermal blankets helping to reduce thermal stresses for other species at low tide. They have also been shown to reduce the erosion of rock materials in laboratory experiments. Asset deterioration is a major climate change risk to hard coastal structures – and costs to repair structures is expected to increase 5-8X! What is poorly known is the biotic-microbial-rock interactions operating underneath these thermal blankets, and also how we can eco-engineer structures to encourage thermal blanket species. A suite of multidisciplinary methodologies will be developed to investigate the impact of thermal blankets. Microscopy, mescocosms and field analyses will be combined to test a variety of thermal blankets, and to explore the conditions that enhance the rate of blanket development and the efficiency of these covers.

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Image Captions

Natural Rocky Shore,Rock biotic interactions,Thermal blankets


Add details about the research methods that will be employed during the project, including fieldwork and placements. Add in details of any collaborations/advisors outside of IAPETUS2 in this section. (365)

The project will involve elements geology, geomorphology, intertidal ecology and microbial. Therefore the student will undertake a truly interdisciplinary PhD.

Objective 1: Novel (rock mass feature based) and standard intertidal monitoring techniques will be used including quadrat counts and SACFOR surveys along with structure for motion surveys of the rock and concrete structures to quantify the geomorphic habitat features. Algal coverage will be determined using a bentho-torch quantify microalgal coverage. The student will identify biodiversity benefits in the field by assessing a combination of material (e.g. different rock types) and rock mass (e.g. different scales of geomorphic habitat features) on provision of thermal refugia for intertidal species. Where tractable, such studies will be conducted at three field locations, with paired contrasting geologies, across the UK to encompass latitudinal gradients of environmental conditions, and associated communities. Eco-engineering designs will also be deployed at all three locations to assess microhabitat conditions as thermal refugia. Do certain characteristics of both natural and artificial substrates convey different benefits under different environmental (latitudinal) regimes. Temperature and humidity data from the field measurements in Objective 1, will provide a set of environmental conditions to test in Objective 2.

Objective 2: Samples of different material types (e.g. limestone, granite, concrete) will be deployed in the field to colonise with microbial communities. These colonised rocks will then be used in novel laboratory based mesocosm experiments to trace microbial interactions and with scanning electron microscopy and 3D chromatography determine rates of interactions between microbial communities and rock material properties.

Objective 3: Thermal blankets can improve conditions for ecology, buffering them from thermal extremes. However, measuring the effects of thermal blankets on rock material or engineering asset condition is weakly studied (see Baxter et al 2022). Microscopy, mescocosms, experimental cabinets and field analyses will be combined to test a variety of thermal blanket properties (e.g. holdfast damage to the substrate, microbial interactions with the rock materials) to determine the combined effects of the cm- dm scale blankets and sub-mm scale microbial-rock interactions on creating thermal refugia for species, as well as the combined effects of these processes on rock material properties and engineering asset condition (see Bone et al. 2022). This will help determine the effects on the rock properties and to explore the conditions that enhance the rate of blanket development and the efficiency of these covers. It will also serve to help elucidate whether the thermal blankets are deteriorative and/or protective of the rock and concrete materials they cover, a crucial gap that can usefully inform eco-engineering advice for practitioners.

Objective 4:
The student will work closely with practitioners to provide a briefing note for creating climate resilient geodiversity biodiversity hotspots as part of coastal engineering practice and on the effects of thermal blankets on asset resilience.

Project Timeline

Year 1

Literature review (M1-3); development of experimental design for field and laboratory experiments; sampling design, site selection and arranging permissions for deploying test samples (M9-12). Attendance of British Society for Geomorphology postgraduate workshop. Writing up the literature review.

Year 2

Installation of field experiments (M12-15); and repeat monitoring of operational sites and data processing and analysis of SfM data (M16-18); laboratory experiments for Obj 2 (M19-24) Attendance at the British Society for Geomorphology Annual Conference; submission of paper related to Obj 1.

Year 3

Further laboratory and field sampling as required. Analysis and write up of Obj 2 and 3 for key journals and working with the case partner to co-produce Objective 4. Implementation. Presentation at the British Ecological Society Annual Conference (M26) and the ICE Coastal Conference (M35).

Year 3.5

Finalise the writing of manuscripts/chapters/briefing note; submit thesis (M37-42).

& Skills

Add information about the training that will be completed during the lifespan of the project and key skills and expertise developed. (114)

The student will receive extensive training under the guidance of the supervisory team, which will be complemented by specific training activities to equip the student with the skills and expertise to become an independent researcher in geomorphology and ecology. Specific training in field and laboratory research methods, including field surveying (e.g. SfM), use of mesocosms and programming with Matlab/Python or R for statistical analysis, image processing and data integration as well as field and laboratory work design and instrumentation. These will be complemented by training in core scientific skills (writing, presentation and science communication) and transferable skills (data management, task coordination and exploitation of results with end users). The student will also work with external partners and in doing so learn about the organisational culture and practice of applying eco-engineering in operational contexts. The lead supervisor has extensive, award-winning knowledge exchange experience which she will share with the student.

The student will also participate in IAPETUS2 training and events, which will complement the personal training plan. The student will also benefit from the extensive and growing research networks the supervisory team have (e.g. via the International Guidelines project) and get the opportunity to participate in some of these larger externally-funded projects if they wish to do so, to further enhance their future employability and training experiences.

References & further reading

1. Kordas et al. 2015. Intertidal community responses to field‐based experimental warming Oikos 124 (7), 888-898.
2. Naylor, L. A. et al. (2017) Greening the Grey. University of Glasgow report. URL: http://eprints.gla.ac.uk/150672/. [Accessed 15/01/2020].
3. Macarthur, M. et al., incl. Naylor, L.A. (2020) Ecological enhancement of coastal engineering structures: passive enhancement techniques. Science of the Total Environment, 740, 139981. (doi: 10.1016/j.scitotenv.2020.139981)
4. Baxter, T.I., Coombes, M.A., Viles, H.A., 2022. No evidence that seaweed cover enhances the deterioration of natural cent‐based mortar in intertidal environments. Earth Surface Processes and Landforms. 1-12.
5. Bone et al. 2022. Biodeterioration and bioprotection of concrete assets in the coastal environment. International Biodeterioration & Biodegradation, Volume 175, https://doi.org/10.1016/j.ibiod.2022.105507.
6. Vye SR, Dickens S, Adams L, Bohn K, Chenery J, Dobson N, Dunn RE, Earp HS, Evans M, Foster C, Grist H, Holt B, Hull S, Jenkins S, Lamont P, Long S, Mieszkowska N, Millard J, Morrall Z, Pack K, Parry-Wilson H, Pocklington J, Pottas J, Richardson L, Scott A, Sugden H, Watson G, West V, Winton D, Delany J, Burrows MT. Patterns of abundance across geographical ranges as a predictor for responses to climate change: Evidence from UK rocky shores. Diversity and Distributions 2020, 26(10), 1357-1365.

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