Multistressor impacts of ocean acidification

and warming on regeneration and biomineralisation in coastal sea urchins content

and warming on regeneration and biomineralisation in coastal sea urchins

This project is based at SAMS UHI, Oban

Ocean acidification and rising sea surface temperatures at high latitudes
Colder water has a higher capacity for absorbing atmospheric carbon dioxide, and in combination with increased microbial communities in coastal water, there is a greater possibility for northern coastal waters having a reduced pH buffering capacity in future climate change scenarios. This can lead to seasonal undersaturation of aragonite, magnesium calcite (MgCa), and other forms of calcite that organisms utilise to build their calcite skeletons. MgCa calcifiers are therefore vulnerable to changing carbonate chemistry in Scottish temperate latitudes due to the trade off in dissolution at lower pH with skeletal strength. Biomineralising organisms such as MgCa sea urchins inhabiting shallow coastal waters are adapted to this dynamic system with extreme environmental fluctuations, but the mechanisms for coping with extended periods of low pH in combination with elevated temperatures predicted in a warming climate are unknown. In particular, it is unclear if multiple stressors will be linear/additive in affect, or act synergistically to exacerbate challenging conditions predicted in future climate change scenarios.

Echinoderm regeneration and biomineralisation
Echinoderms are renowned for their regenerative abilities, mostly studied in starfish arm regeneration and sea cucumber internal organ evisceration. Sea urchins are a new and promising model for echinoderm regeneration and biomineralisation due to the extensive molecular, developmental, genetic, and genomic tools available, and their environmental importance in ubiquitous coastal ecosystems. Sea urchins have a demonstrated capacity for wound healing and extensive regrowth of MgCa spine structures, outer epidermis, and tube feet muscle and neural tissues, and their open circulatory system allows the immune cells to access all tissues and drive the regeneration processes. The model has also provided the first evidence of involvement of stem cells in the regeneration process in echinoderms. The gene regulatory networks and molecular pathways that guide regeneration and skeletogenesis in echinoderms are well-resolved, we have a good understanding of how urchins build and repair their skeletons, but less is known about how they will cope with the multiple stressors of climate change. The wealth of mechanistic understanding in urchins, from genotype to phenotype, in addition to their ecological importance, makes them the perfect model to probe and predict the biological impacts of multiple climate-stressors.

The project

The studentship will centre on two inter-connected questions: How will sea urchins remineralise and regenerate their tissues in a future multi-stressor environment? And Are the effects of multiple climate-change associated stressors additive, antagonistic, or synergistic? It will utilise the sea urchin regeneration assay to investigate multiple-climatic stressors using experimental conditions of ocean acidification (OA) and warming. The phenotypic assay has been developed to visualise and quantify spine and tube feet regeneration from a single ambulacral section, by photographing regrowth underwater and analysing the images. In addition to the phenotypic assay, molecular and cellular analyses will be included: targeted gene expression, in-situ hybridisation, and histology on regenerating tube feet and spines, with the potential for complementary transcriptomics and proteomics, representing analyses across levels of biological organisation from genes, cells, and organismal physiology.  Comparison experiments with different species will investigate interspecific variation in stressor susceptibility, and species from different latitudinal distributions will provide insight into cold-adapted or warmer-adapted mechanisms. Elemental ratio analysis of calcium carbonate structures will allow characterisation of magnesium content and provide further insights into possible skeletal trade-offs under OA and elevated temperature conditions.

Environmental multi-stressor studies rely heavily on ecological impacts on community responses, and there is the need to drive the research to encompass molecular analyses, which can elucidate the underpinning mechanisms driving the larger ecological changes. The proposed research will enable a truly interdisciplinary approach, spanning ecology, environmental biology, ecotoxicology, and molecular, biochemical, and biomechanical analyses for a holistic understanding of impacts and effects.

The project is co-supervised by Prof. Michael Burrows (SAMS UHI), Dr Helena Reinardy (SAMS UHI), and Dr Victoria Sleight (University of Aberdeen). The studentship will be based at SAMS UHI which has suitable aquarium facilities with sea urchin stocks and molecular biology, biochemistry, and analytical chemistry laboratories. It is anticipated that 1 year of the studentship will be a placement in the Sleight Laboratory.

The start date of this project is: 27 September 2021

The candidate should have experience in molecular biology, biochemistry, gene expression, histology, and good husbandry and handling of aquatic organisms is highly recommended.

Contacts and supervisory team for this project: content

Contacts and supervisory team for this project:

Project specific enquiries:

Prof Michael Burrows,

Dr Helena Reinardy,

Dr Victoria Sleight,

General enquiries: Graduate School Office

Supervisory team (click name to view research profile):

Prof Michael Burrows, SAMS UHI

Dr Helena Reinardy, SAMS UHI